U.S. patent application number 13/901620 was filed with the patent office on 2013-10-17 for process for production of acrylic acid or its derivatives.
This patent application is currently assigned to The Procter & Gamble Company. The applicant listed for this patent is The Procter & Gamble Company. Invention is credited to Dimitris Ioannis Collias, Jane Ellen Godlewski, Juan Estaban Velasquez, Janette Villalobos.
Application Number | 20130274517 13/901620 |
Document ID | / |
Family ID | 49325675 |
Filed Date | 2013-10-17 |
United States Patent
Application |
20130274517 |
Kind Code |
A1 |
Godlewski; Jane Ellen ; et
al. |
October 17, 2013 |
Process For Production Of Acrylic Acid Or Its Derivatives
Abstract
Processes for the catalytic dehydration of hydroxypropionic
acid, hydroxypropionic acid derivatives, or mixtures thereof to
acrylic acid, acrylic acid derivatives, or mixtures thereof with
high yield and selectivity and without significant conversion to
undesired side products, such as, acetaldehyde, propanoic acid, and
acetic acid, are provided. The processes can be carried out either
in a gas phase or in a liquid phase.
Inventors: |
Godlewski; Jane Ellen;
(Loveland, OH) ; Villalobos; Janette; (Cincinnati,
OH) ; Collias; Dimitris Ioannis; (Mason, OH) ;
Velasquez; Juan Estaban; (Cincinnati, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The Procter & Gamble Company |
Cincinnati |
OH |
US |
|
|
Assignee: |
The Procter & Gamble
Company
Cincinnati
OH
|
Family ID: |
49325675 |
Appl. No.: |
13/901620 |
Filed: |
May 24, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13838692 |
Mar 15, 2013 |
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13901620 |
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13760483 |
Feb 6, 2013 |
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13838692 |
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61623054 |
Apr 11, 2012 |
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Current U.S.
Class: |
562/599 |
Current CPC
Class: |
C07C 51/377 20130101;
B01J 37/08 20130101; B01J 27/1806 20130101; B01J 37/0036 20130101;
C07C 57/04 20130101; C07C 51/377 20130101; B01J 35/023
20130101 |
Class at
Publication: |
562/599 |
International
Class: |
C07C 51/377 20060101
C07C051/377 |
Claims
1) A process for converting hydroxypropionic acid, hydroxypropionic
acid derivatives, or mixtures thereof to acrylic acid, acrylic acid
derivatives, or mixtures thereof comprising the following steps: a)
Providing an aqueous solution comprising hydroxypropionic acid,
hydroxypropionic acid derivatives, or mixtures thereof, wherein
said hydroxypropionic acid is in monomeric form in said aqueous
solution; b) Combining said aqueous solution with an inert gas to
form an aqueous solution/gas blend; c) Evaporating said aqueous
solution/gas blend to produce a gaseous mixture; and d) Dehydrating
said gaseous mixture by contacting said gaseous mixture with a
dehydration catalyst under a pressure of at least about 80 psig,
producing said acrylic acid, acrylic acid derivatives, or mixtures
thereof.
2) The process of claim 1, wherein the pressure is from about 80
psig to about 550 psig.
3) The process of claim 1, wherein the pressure is from about 150
psig to about 500 psig.
4) The process of claim 1, wherein the temperature during the
evaporating step is from about 165.degree. C. to about 450.degree.
C.
5) The process of claim 1, wherein the temperature during the
evaporating step is from about 250.degree. C. to about 375.degree.
C.
6) The process of claim 1, wherein the GHSV in the evaporating step
is from about 720 h.sup.-1 to about 36,000 h.sup.-1.
7) The process of claim 1, wherein the temperature during the
dehydrating step is from about 150.degree. C. to about 500.degree.
C.
8) The process of claim 1, wherein the temperature during the
dehydrating step is from about 300.degree. C. to about 450.degree.
C.
9) The process of claim 1, wherein the GHSV in the dehydrating step
is from about 720 h.sup.-1 to about 36,000 h.sup.-1.
10) The process of claim 1, wherein the GHSV in the dehydrating
step is about 3,600 h.sup.-1.
11) The process of claim 1, wherein the hydroxypropionic acid,
hydroxypropionic acid derivatives, or mixtures thereof comprise
from about 5 wt % to about 50 wt % of said aqueous solution.
12) The process of claim 1, wherein the hydroxypropionic acid,
hydroxypropionic acid derivatives, or mixtures thereof comprise
from about 10 wt % to about 25 wt % of said aqueous solution.
13) The process of claim 1, wherein the inert gas is selected from
the group consisting of air, nitrogen, helium, argon, carbon
dioxide, carbon monoxide, steam, and mixtures thereof.
14) The process of claim 1, wherein the gaseous mixture comprises
from about 1 mol % to about 10 mol % of said hydroxypropionic acid,
hydroxypropionic acid derivatives, or mixtures thereof.
15) The process of claim 1, wherein said evaporating step is
performed in a reactor, wherein said reactor has an interior
surface comprising material selected from the group consisting of
quartz, borosilicate glass, silicon, hastelloy, inconel,
manufactured sapphire, stainless steel, and mixtures thereof.
16) The process of claim 1, wherein said dehydrating step is
performed in a reactor, wherein said reactor has an interior
surface comprising material selected from the group consisting of
quartz, borosilicate glass, silicon, hastelloy, inconel,
manufactured sapphire, stainless steel, and mixtures thereof.
17) The process of claim 1, wherein said hydroxypropionic acid is
lactic acid.
18) The process of claim 17, wherein the acrylic acid selectivity
from the lactic acid is at least 50%.
19) The process of claim 17, wherein the acrylic acid selectivity
from the lactic acid is at least 80%.
20) The process of claim 17, wherein the propanoic acid selectivity
from the lactic acid is less than about 5%.
21) The process of claim 17, wherein the propanoic acid selectivity
from the lactic acid is less than about 1%.
22) The process of claim 17, wherein the conversion of said lactic
acid is more than about 50%.
23) The process of claim 17, wherein the conversion of said lactic
acid is more than about 80%.
24) The process of claim 1, wherein said evaporating step is
performed under a pressure of from about 80 psig to about 550
psig.
25) A process for converting hydroxypropionic acid,
hydroxypropionic acid derivatives, or mixtures thereof to acrylic
acid, acrylic acid derivatives, or mixtures thereof comprising the
following steps: a) Providing an aqueous solution comprising
hydroxypropionic acid, hydroxypropionic acid derivatives, or
mixtures thereof, wherein said hydroxypropionic acid comprises
oligomers in said aqueous solution; b) Heating said aqueous
solution at a temperature from about 50.degree. C. to about
100.degree. C. to remove said oligomers of said hydroxypropionic
acid and produce an aqueous solution of monomeric hydroxypropionic
acid; c) Combining said aqueous solution of monomeric
hydroxypropionic acid with an inert gas to form an aqueous
solution/gas blend; d) Evaporating said aqueous solution/gas blend
to produce a gaseous mixture; and e) Dehydrating said gaseous
mixture by contacting said mixture with a dehydration catalyst,
producing said acrylic acid, acrylic acid derivatives and mixtures
thereof.
26) The process of claim 25, wherein, after said heating step, said
oligomers comprise less than about 5 wt % based on the total amount
of hydroxypropionic acid, hydroxypropionic acid derivatives, or
mixtures thereof.
27) A process for converting hydroxypropionic acid,
hydroxypropionic acid derivatives, or mixtures thereof to acrylic
acid, acrylic acid derivatives, or mixtures thereof comprising the
following steps: a) Providing an aqueous solution comprising
hydroxypropionic acid, hydroxypropionic acid derivatives, or
mixtures thereof, wherein said hydroxypropionic acid is in
monomeric form in said aqueous solution; b) Combining said aqueous
solution with an inert gas to form an aqueous solution/gas blend;
c) Evaporating said aqueous solution/gas blend to produce a gaseous
mixture; d) Dehydrating said gaseous mixture by contacting said
mixture with a dehydration catalyst, producing said acrylic acid,
acrylic acid derivatives, or mixtures thereof; and e) Cooling said
acrylic acid, acrylic acid derivatives, or mixtures thereof at a
GHSV of more than about 360 H.sup.-1.
28) The process of claim 27, wherein the GHSV in the cooling step
is more than about 720 h.sup.-1.
29) A process for converting lactic acid to acrylic acid comprising
the following steps: a) Diluting an about 88% lactic acid aqueous
solution with water to form an about 20 wt % lactic acid aqueous
solution; b) Heating said about 20 wt % lactic acid aqueous
solution at a temperature from about 95.degree. C. to about
100.degree. C. to remove oligomers of said lactic acid, producing a
monomeric lactic acid aqueous solution comprising at least 95 wt %
of said lactic acid in monomeric form based on the total amount of
lactic acid; c) Combining said monomeric lactic acid aqueous
solution with nitrogen to form an aqueous solution/gas blend; d)
Evaporating said aqueous solution/gas blend in a reactor with
inside surface of borosilicate glass at a GHSV of about 7,200
h.sup.-1 at a temperature from about 300.degree. C. to about
350.degree. C. to produce a gaseous mixture comprising about 2.5
mol % lactic acid and about 50 mol % water; e) Dehydrating said
gaseous mixture in a reactor with inside surface of borosilicate
glass at a GHSV of about 3,600 h.sup.-1 at a temperature from about
350.degree. C. to about 425.degree. C. by contacting said mixture
with a dehydration catalyst under a pressure of about 360 psig,
producing said acrylic acid; and f) Cooling said acrylic acid to
give an acrylic acid solution at a GHSV from about 360 h.sup.-1 to
about 36,000 h.sup.-1.
30) A process for converting hydroxypropionic acid, derivatives of
hydroxypropionic acid, and mixtures thereof to acrylic acid,
acrylic acid derivatives, or mixtures thereof comprising the
following steps: a) Providing an aqueous solution comprising
hydroxypropionic acid, hydroxypropionic acid derivatives, or
mixtures thereof, wherein said hydroxypropionic acid is in
monomeric form in said aqueous solution, and wherein the
hydroxypropionic acid, hydroxypropionic acid derivatives, or
mixtures thereof comprise from about 10 wt % to about 25 wt % of
said aqueous solution; b) Combining said aqueous solution with an
inert gas to form an aqueous solution/gas blend; c) Evaporating
said aqueous solution/gas blend to produce a gaseous mixture; and
d) Dehydrating said gaseous mixture by contacting said mixture with
a dehydration catalyst producing said acrylic acid, acrylic acid
derivatives, or mixtures thereof.
31) The process of claim 30, wherein the hydroxypropionic acid,
hydroxypropionic acid derivatives, or mixtures thereof comprise
about 20 wt % of said aqueous solution.
32) A process for converting alkyl lactates to acrylic acid,
acrylic acid derivatives, or mixtures thereof comprising the
following steps: a) Providing alkyl lactates or a solution
comprising alkyl lactates and a solvent; b) Combining said alkyl
lactates or said solution comprising said alkyl lactates and said
solvent with an inert gas to form a liquid/gas blend; c)
Evaporating said liquid/gas blend to produce a gaseous mixture; and
d) Dehydrating said gaseous mixture by contacting said gaseous
mixture with a dehydration catalyst under a pressure of at least
about 80 psig, producing said acrylic acid, acrylic acid
derivatives, or mixtures thereof.
33) The process of claim 32, wherein said alkyl lactates are
selected from the group consisting of methyl lactate, ethyl
lactate, butyl lactate, 2-ethylhexyl lactate, and mixtures
thereof.
34) The process of claim 32, wherein the solvent is selected from
the group consisting of water, methanol, ethanol, butanol,
2-ethylhexanol, isobutanol, isooctyl alcohol, and mixtures
thereof.
35) A process for converting hydroxypropionic acid,
hydroxypropionic acid derivatives, or mixtures thereof to acrylic
acid, acrylic acid derivatives, or mixtures thereof comprising the
following steps: a) Providing a solution comprising
hydroxypropionic acid, hydroxypropionic acid derivatives, or
mixtures thereof, wherein said hydroxypropionic acid is in
monomeric form in said solution; and b) Dehydrating said
hydroxypropionic acid, hydroxypropionic acid derivatives, or
mixtures thereof by contacting said solution with a dehydration
catalyst under a pressure of at least about 80 psig, producing said
acrylic acid, acrylic acid derivatives, or mixtures thereof.
Description
FIELD OF THE INVENTION
[0001] The present invention generally relates to processes that
catalytically convert hydroxypropionic acid, hydroxypropionic acid
derivatives, or mixtures thereof to acrylic acid, acrylic acid
derivatives, or mixtures thereof. More specifically, the invention
relates to processes useful for the dehydration of hydroxypropionic
acid, hydroxypropionic acid derivatives, or mixtures thereof to
acrylic acid, acrylic acid derivatives, or mixtures thereof with
high yield and selectivity to acrylic acid, acrylic acid
derivatives, or mixtures thereof, short residence time, and without
significant conversion of the hydroxypropionic acid,
hydroxypropionic acid derivatives, or mixtures thereof to undesired
side products, such as, for example, acetaldehyde, propanoic acid,
acetic acid, 2,3-pentanedione, carbon dioxide, and carbon monoxide.
The process can be carried out either in a gas phase or in a liquid
phase.
BACKGROUND OF THE INVENTION
[0002] Acrylic acid, acrylic acid derivatives, or mixtures thereof
have a variety of industrial uses, typically consumed in the form
of polymers. In turn, these polymers are commonly used in the
manufacture of, among other things, adhesives, binders, coatings,
paints, polishes, detergents, flocculants, dispersants, thixotropic
agents, sequestrants, and superabsorbent polymers, which are used
in disposable absorbent articles, including diapers and hygienic
products, for example. Acrylic acid is commonly made from petroleum
sources. For example, acrylic acid has long been prepared by
catalytic oxidation of propylene. These and other methods of making
acrylic acid from petroleum sources are described in the
Kirk-Othmer Encyclopedia of Chemical Technology, Vol. 1, pgs.
342-369 (5.sup.th Ed., John Wiley & Sons, Inc., 2004).
Petroleum-based acrylic acid contributes to greenhouse emissions
due to its high petroleum derived carbon content. Furthermore,
petroleum is a non-renewable material, as it takes hundreds of
thousands of years to form naturally and only a short time to
consume. As petrochemical resources become increasingly scarce,
more expensive, and subject to regulations for CO.sub.2 emissions,
there exists a growing need for bio-based acrylic acid, acrylic
acid derivatives, or mixtures thereof that can serve as an
alternative to petroleum-based acrylic acid, acrylic acid
derivatives, or mixtures thereof.
[0003] Many attempts have been made over the last 40 to 50 years to
make bio-based acrylic acid, acrylic acid derivatives, or mixtures
thereof from non-petroleum sources, such as lactic acid (also known
as 2-hydroxypropionic acid), 3-hydroxypropionic acid, glycerin,
carbon monoxide and ethylene oxide, carbon dioxide and ethylene,
and crotonic acid. From these non-petroleum sources, only lactic
acid is produced today in high yield from sugar (.gtoreq.90% of
theoretical yield, or equivalently, .gtoreq.0.9 g of lactic acid
per g of sugar) and purity, and economics which could support
producing acrylic acid cost competitively to petroleum-based
acrylic acid. As such, lactic acid or lactate presents a real
opportunity of serving as feedstock for bio-based acrylic acid,
acrylic acid derivatives, or mixtures thereof. Also,
3-hydroxypropionic acid is expected to be produced at commercial
scale in a few years, and as such, 3-hydropropionic acid will
present another real opportunity of serving as feedstock for
bio-based acrylic acid, acrylic acid derivatives, or mixtures
thereof. Sulfate salts; phosphate salts; mixtures of sulfate and
phosphate salts; bases; zeolites or modified zeolites; metal oxides
or modified metal oxides; and supercritical water are the main
catalysts which have been used to dehydrate lactic acid or lactate
to acrylic acid, acrylic acid derivatives, or mixtures thereof in
the past with varying success.
[0004] For example, in U.S. Pat. No. 4,786,756 (issued in 1988),
the inventors claim the vapor phase dehydration of lactic acid or
ammonium lactate to acrylic acid using aluminum phosphate
(AlPO.sub.4) treated with an aqueous inorganic base as a catalyst.
As examples, the '756 patent discloses a maximum yield of acrylic
acid of 43.3% when lactic acid was fed into the reactor at
approximately atmospheric pressure, and a respective yield of 61.1%
when ammonium lactate was fed into the reactor. In both examples,
acetaldehyde was produced at yields of 34.7% and 11.9%,
respectively, and other side products were also present in large
quantities, such as, propionic acid, CO, and CO.sub.2. Omission of
the base treatment caused increased amounts of the side products.
Another example is Hong et al. (2011) Appl. Catal. A: General
396:194-200, who developed and tested composite catalysts made with
Ca.sub.3(PO.sub.4).sub.2 and Ca.sub.2(P.sub.2O.sub.7) salts with a
slurry-mixing method. The catalyst with the highest yield of
acrylic acid from methyl lactate was the 50%-50% (by weight)
catalyst. It yielded 68% acrylic acid, about 5% methyl acrylate,
and about 14% acetaldehyde at 390.degree. C. The same catalyst
achieved 54% yield of acrylic acid, 14% yield of acetaldehyde, and
14% yield of propionic acid from lactic acid.
[0005] Prof. D. Miller's group at Michigan State University (MSU)
published many papers on the dehydration of lactic acid or lactic
acid esters to acrylic acid and 2,3-pentanedione, such as, Gunter
et al. (1994) J. Catalysis 148:252-260; and Tam et al. (1999) Ind.
Eng. Chem. Res.38:3873-3877. The best acrylic acid yields reported
by the group were about 33% when lactic acid was dehydrated at
350.degree. C. over low surface area and pore volume silica
impregnated with NaOH. In the same experiment, the acetaldehyde
yield was 14.7% and the propionic acid yield was 4.1%. Examples of
other catalysts tested by the group were Na.sub.2SO.sub.4, NaCl,
Na.sub.3PO.sub.4, NaNO.sub.3, Na.sub.2SiO.sub.3,
Na.sub.4P.sub.2O.sub.7, NaH.sub.2PO.sub.4, Na.sub.2HPO.sub.4,
Na.sub.2HAsO.sub.4, NaC.sub.3H.sub.5O.sub.3, NaOH, CsCl,
Cs.sub.2SO.sub.4, KOH, CsOH, and LiOH. In all cases, the above
referenced catalysts were tested as individual components, not in
mixtures. Finally, the group suggested that the yield to acrylic
acid is improved and the yield to the side products is suppressed
when the surface area of the silica support is low, reaction
temperature is high, reaction pressure is low, and residence time
of the reactants in the catalyst bed is short.
[0006] Finally, the Chinese patent application 200910054519.7
discloses the use of ZSM-5 molecular sieves modified with aqueous
alkali (such as, NH.sub.3, NaOH, and Na.sub.2CO.sub.3) or a
phosphoric acid salt (such as, NaH.sub.2PO.sub.4,
Na.sub.2HPO.sub.4, LiH.sub.2PO.sub.4, LaPO.sub.4, etc.). The best
yield of acrylic acid achieved in the dehydration of lactic acid
was 83.9%, however that yield came at very long residence
times.
[0007] Therefore, the manufacture of acrylic acid, acrylic acid
derivatives, or mixtures thereof from lactic acid or lactate by
processes, such as those described in the literature noted above,
leads to: 1) yields of acrylic acid, acrylic acid derivatives, or
mixtures thereof not exceeding 70%; 2) low selectivities of acrylic
acid, acrylic acid derivatives, or mixtures thereof, i.e.,
significant amounts of undesired side products, such as,
acetaldehyde, 2,3-pentanedione, propionic acid, CO, and CO.sub.2;
3) long residence times in the catalyst beds; and 4) catalyst
deactivation in short time on stream (TOS). The side products can
deposit onto the catalyst resulting in fouling, and premature and
rapid deactivation of the catalyst. Further, once deposited, these
side products can catalyze other undesired reactions, such as
polymerization reactions. Aside from depositing on the catalysts,
these side products, even when present in only small amounts,
impose additional costs in processing acrylic acid (when present in
the reaction product effluent) in the manufacture of superabsorbent
polymers (SAP), for example. These deficiencies of the prior art
processes and catalysts render them commercially non-viable.
[0008] Accordingly, there is a need for processes for the
dehydration of hydroxypropionic acid, hydroxypropionic acid
derivatives, or mixtures thereof to acrylic acid, acrylic acid
derivatives, or mixtures thereof, with high yield, selectivity, and
efficiency (i.e., short residence time), and high longevity
catalysts.
SUMMARY OF THE INVENTION
[0009] In one embodiment of the present invention, a process for
converting hydroxypropionic acid, hydroxypropionic acid
derivatives, or mixtures thereof to acrylic acid, acrylic acid
derivatives, or mixtures thereof is provided comprising the
following steps: [0010] a) Providing an aqueous solution comprising
hydroxypropionic acid, hydroxypropionic acid derivatives, or
mixtures thereof, wherein said hydroxypropionic acid is in
monomeric form in said aqueous solution; [0011] b) Combining said
aqueous solution with an inert gas to form an aqueous solution/gas
blend; [0012] c) Evaporating said aqueous solution/gas blend to
produce a gaseous mixture; and [0013] d) Dehydrating said gaseous
mixture by contacting said gaseous mixture with a dehydration
catalyst under a pressure of at least about 80 psig, producing said
acrylic acid, acrylic acid derivatives, or mixtures thereof.
[0014] In another embodiment of the present invention, a process
for converting hydroxypropionic acid, hydroxypropionic acid
derivatives, or mixtures thereof to acrylic acid, acrylic acid
derivatives, or mixtures thereof is provided comprising the
following steps: [0015] a) Providing an aqueous solution comprising
hydroxypropionic acid, hydroxypropionic acid derivatives, or
mixtures thereof, wherein said hydroxypropionic acid comprises
oligomers in said aqueous solution; [0016] b) Heating said aqueous
solution at a temperature from about 50.degree. C. to about
100.degree. C. to remove said oligomers of said hydroxypropionic
acid and produce an aqueous solution of monomeric hydroxypropionic
acid; [0017] c) Combining said aqueous solution of monomeric
hydroxypropionic acid with an inert gas to form an aqueous
solution/gas blend; [0018] d) Evaporating said aqueous solution/gas
blend to produce a gaseous mixture; and [0019] e) Dehydrating said
gaseous mixture by contacting said mixture with a dehydration
catalyst, producing said acrylic acid, acrylic acid derivatives and
mixtures thereof.
[0020] In yet another embodiment of the present invention, a
process for converting hydroxypropionic acid, hydroxypropionic acid
derivatives, or mixtures thereof to acrylic acid, acrylic acid
derivatives, or mixtures thereof is provided comprising the
following steps: [0021] a) Providing an aqueous solution comprising
hydroxypropionic acid, hydroxypropionic acid derivatives, or
mixtures thereof, wherein said hydroxypropionic acid is in
monomeric form in said aqueous solution; [0022] b) Combining said
aqueous solution with an inert gas to form an aqueous solution/gas
blend; [0023] c) Evaporating said aqueous solution/gas blend to
produce a gaseous mixture; [0024] d) Dehydrating said gaseous
mixture by contacting said mixture with a dehydration catalyst,
producing said acrylic acid, acrylic acid derivatives, or mixtures
thereof; and [0025] e) Cooling said acrylic acid, acrylic acid
derivatives, or mixtures thereof at a GHSV of more than about 360
h.sup.-1.
[0026] In one embodiment of the present invention, a process for
converting lactic acid to acrylic acid is provided comprising the
following steps: [0027] a) Diluting an about 88% lactic acid
aqueous solution with water to form an about 20 wt % lactic acid
aqueous solution; [0028] b) Heating said about 20 wt % lactic acid
aqueous solution at a temperature from about 95.degree. C. to about
100.degree. C. to remove oligomers of said lactic acid, producing a
monomeric lactic acid aqueous solution comprising at least 95 wt %
of said lactic acid in monomeric form based on the total amount of
lactic acid; [0029] c) Combining said monomeric lactic acid aqueous
solution with nitrogen to form an aqueous solution/gas blend;
[0030] d) Evaporating said aqueous solution/gas blend in a reactor
with inside surface of borosilicate glass at a GHSV of about 7,200
h.sup.-1 at a temperature from about 300.degree. C. to about
350.degree. C. to produce a gaseous mixture comprising about 2.5
mol % lactic acid and about 50 mol % water; [0031] e) Dehydrating
said gaseous mixture in a reactor with inside surface of
borosilicate glass at a GHSV of about 3,600 h.sup.-1 at a
temperature from about 350.degree. C. to about 425.degree. C. by
contacting said mixture with a dehydration catalyst under a
pressure of about 360 psig, producing said acrylic acid; and [0032]
f) Cooling said acrylic acid to give an acrylic acid solution at a
GHSV from about 360 h.sup.-1 to about 36,000 h.sup.-1.
[0033] In another embodiment of the present invention, a process
for converting hydroxypropionic acid, derivatives of
hydroxypropionic acid, and mixtures thereof to acrylic acid,
acrylic acid derivatives, or mixtures thereof is provided
comprising the following steps: [0034] a) Providing an aqueous
solution comprising hydroxypropionic acid, hydroxypropionic acid
derivatives, or mixtures thereof, wherein said hydroxypropionic
acid is in monomeric form in said aqueous solution, and wherein the
hydroxypropionic acid, hydroxypropionic acid derivatives, or
mixtures thereof comprise from about 10 wt % to about 25 wt % of
said aqueous solution; [0035] b) Combining said aqueous solution
with an inert gas to form an aqueous solution/gas blend; [0036] c)
Evaporating said aqueous solution/gas blend to produce a gaseous
mixture; and [0037] d) Dehydrating said gaseous mixture by
contacting said mixture with a dehydration catalyst producing said
acrylic acid, acrylic acid derivatives, or mixtures thereof.
[0038] In yet another embodiment of the present invention, a
process for converting alkyl lactates to acrylic acid, acrylic acid
derivatives, or mixtures thereof is provided comprising the
following steps: [0039] a) Providing alkyl lactates or a solution
comprising alkyl lactates and a solvent; [0040] b) Combining said
alkyl lactates or said solution comprising said alkyl lactates and
said solvent with an inert gas to form a liquid/gas blend; [0041]
c) Evaporating said liquid/gas blend to produce a gaseous mixture;
and [0042] d) Dehydrating said gaseous mixture by contacting said
gaseous mixture with a dehydration catalyst under a pressure of at
least about 80 psig, producing said acrylic acid, acrylic acid
derivatives, or mixtures thereof.
[0043] In another embodiment of the present invention, a process
for converting hydroxypropionic acid, hydroxypropionic acid
derivatives, or mixtures thereof to acrylic acid, acrylic acid
derivatives, or mixtures thereof is provided comprising the
following steps: [0044] a) providing a solution comprising
hydroxypropionic acid, hydroxypropionic acid derivatives, or
mixtures thereof, wherein said hydroxypropionic acid is in
monomeric form in said solution; and [0045] b) dehydrating said
hydroxypropionic acid, hydroxypropionic acid derivatives, or
mixtures thereof by contacting said solution with a dehydration
catalyst under a pressure of at least about 80 psig, producing said
acrylic acid, acrylic acid derivatives, or mixtures thereof.
[0046] Additional features of the invention may become apparent to
those skilled in the art from a review of the following detailed
description, taken in conjunction with the examples and the
appended claims.
DETAILED DESCRIPTION OF THE INVENTION
I Definitions
[0047] As used herein, the term "condensed phosphate" refers to any
salts containing one or several P--O--P bonds generated by corner
sharing of PO.sub.4 tetrahedra.
[0048] As used herein, the term "cyclophosphate" refers to any
cyclic condensed phosphate constituted of two or more
corner-sharing PO.sub.4 tetrahedra.
[0049] As used herein, the term "monophosphate" or "orthophosphate"
refers to any salt whose anionic entity, [PO.sub.4].sup.3-, is
composed of four oxygen atoms arranged in an almost regular
tetrahedral array about a central phosphorus atom.
[0050] As used herein, the term "oligophosphate" refers to any
polyphosphates that contain five or less PO.sub.4 units.
[0051] As used herein, the term "polyphosphate" refers to any
condensed phosphates containing linear P--O--P linkages by corner
sharing of PO.sub.4 tetrahedra leading to the formation of finite
chains.
[0052] As used herein, the term "ultraphosphate" refers to any
condensed phosphate where at least two PO.sub.4 tetrahedra of the
anionic entity share three of their corners with the adjacent
ones.
[0053] As used herein, the term "cation" refers to any atom or
group of covalently-bonded atoms having a positive charge.
[0054] As used herein, the term "monovalent cation" refers to any
cation with a positive charge of +1.
[0055] As used herein, the term "polyvalent cation" refers to any
cation with a positive charge equal or greater than +2.
[0056] As used herein, the term "anion" refers to any atom or group
of covalently-bonded atoms having a negative charge.
[0057] As used herein, the term "heteropolyanion" refers to any
anion with covalently bonded XO.sub.p and YO.sub.r polyhedra, and
thus includes X--O--Y and possibly X--O--X and Y--O--Y bonds,
wherein X and Y represent any atoms, and wherein p and r are any
positive integers.
[0058] As used herein, the term "heteropolyphosphate" refers to any
heteropolyanion, wherein X represents phosphorus (P) and Y
represents any other atom.
[0059] As used herein, the term "phosphate adduct" refers to any
compound with one or more phosphate anions and one or more
non-phosphate anions that are not covalently linked.
[0060] As used herein, the terms "LA" refers to lactic acid, "AA"
refers to acrylic acid, "AcH" refers to acetaldehyde, and "PA"
refers to propionic acid.
[0061] As used herein, the term "particle span" refers to a
statistical representation of a given particle sample and is equal
to (D.sub.v,0.90-D.sub.v,0.10)/D.sub.v,0.50. The term "median
particle size" or D.sub.v,0.50 refers to the diameter of a particle
below which 50% of the total volume of particles lies. Further,
D.sub.v,0.10 refers to the particle size that separates the
particle sample at the 10% by volume fraction and D.sub.v,0.90, is
the particle size that separates the particle sample at the 90% by
volume fraction.
[0062] As used herein, the term "conversion" in % is defined as
[hydroxypropionic acid, hydroxypropionic acid derivatives, or
mixtures thereof flow rate in (mol/min)--hydroxypropionic acid,
hydroxypropionic acid derivatives, or mixtures thereof flow rate
out (mol/min)]/[hydroxypropionic acid, hydroxypropionic acid
derivatives, or mixtures thereof flow rate in (mol/min)] *100. For
the purposes of this invention, the term "conversion" means molar
conversion, unless otherwise noted.
[0063] As used herein, the term "yield" in % is defined as [product
flow rate out (mol/min)/hydroxypropionic acid, hydroxypropionic
acid derivatives, or mixtures thereof flow rate in (mol/min)]*100.
For the purposes of this invention, the term "yield" means molar
yield, unless otherwise noted.
[0064] As used herein, the term "selectivity" in % is defined as
[Yield/Conversion]*100. For the purposes of this invention, the
term "selectivity" means molar selectivity, unless otherwise
noted.
[0065] As used herein, the term "total flow rate out" in mol/min
and for hydroxypropionic acid is defined as: (2/3)*[C2 flow rate
out (mol/min)]+[C3 flow rate out (mol/min)]+(2/3)*[acetaldehyde
flow rate out (mol/min)]+(4/3)*[C4 flow rate out
(mol/min)]+[hydroxypropionic acid flow rate out (mol/min)]+[pyruvic
acid flow rate out (mol/min)]+(2/3)*[acetic acid flow rate out
(mol/min)]+[1,2-propanediol flow rate out (mol/min)]+[propionic
acid flow rate out (mol/min)]+[acrylic acid flow rate out
(mol/min)]+(5/3)*[2,3-pentanedione flow rate out
(mol/min)]+(1/3)*[carbon monoxide flow rate out
(mol/min)]+(1/3)*[carbon dioxide flow rate out (mol/min)]. If a
hydroxypropionic acid derivative is used instead of
hydroxypropionic acid, the above formula needs to be adjusted
according to the number of carbon atoms in the hydroxypropionic
acid derivative.
[0066] As used herein, the term "C2" means ethane and ethylene.
[0067] As used herein, the term "C3" means propane and
propylene.
[0068] As used herein, the term "C4" means butane and butenes.
[0069] As used herein, the term "total molar balance" or "TMB" in %
is defined as [total flow rate out (mol/min)/hydroxypropionic acid,
hydroxypropionic acid derivatives, or mixtures thereof flow rate in
(mol/min)]*100.
[0070] As used herein, the term "the acrylic acid yield was
corrected for TMB" is defined as [acrylic acid yield/total molar
balance]*100, to account for slightly higher flows in the
reactor.
[0071] As used herein, the term "Gas Hourly Space Velocity" or
"GHSV" in H.sup.-1 is defined as [Total gas flow rate
(mL/min)/catalyst bed volume (mL)].times.60. The total gas flow
rate is calculated under Standard Temperature and Pressure
conditions (STP; 0.degree. C. and 1 atm).
[0072] As used herein, the term "Liquid Hourly Space Velocity" or
"LHSV" in H.sup.-1 is defined as [Total liquid flow rate
(mL/min)/catalyst bed volume (mL)].times.60.
II Process
[0073] The inventors have unexpectedly found that the process of
dehydrating hydroxypropionic acid, hydroxypropionic acid
derivatives, or mixtures thereof can produce high yield to and
selectivity of acrylic acid, acrylic acid derivatives, or mixtures
thereof when the solution of hydroxypropionic acid,
hydroxypropionic acid derivatives, or mixtures thereof has the
hydroxypropionic acid in monomeric form and it is combined with an
inert gas, and the process includes an evaporation step and a
dehydration step. Furthermore, a cooling step with a short
residence time, downstream of the dehydration step, and operating
the dehydration step under a pressure of 80 psig or more aid in the
achievement of the high yield and selectivity of acrylic acid,
acrylic acid derivatives, or mixtures thereof.
[0074] A process for converting hydroxypropionic acid,
hydroxypropionic acid derivatives, or mixtures thereof to acrylic
acid, acrylic acid derivatives, or mixtures thereof of the present
invention comprises the following steps: a) providing an aqueous
solution comprising hydroxypropionic acid, hydroxypropionic acid
derivatives, or mixtures thereof, wherein said hydroxypropionic
acid is in monomeric form in the aqueous solution; b) combining the
aqueous solution with an inert gas to form an aqueous solution/gas
blend; c) evaporating the aqueous solution gas/blend to produce a
gaseous mixture; and d) dehydrating the gaseous mixture by
contacting the mixture with a dehydration catalyst under a pressure
of at least about 80 psig.
[0075] Hydroxypropionic acid can be 3-hydroxypropionic acid,
2-hydroxypropionic acid (also called, lactic acid), 2-methyl
hydroxypropionic acid, or mixtures thereof. Derivatives of
hydroxypropionic acid can be metal or ammonium salts of
hydroxypropionic acid, alkyl esters of hydroxypropionic acid, alkyl
esters of 2-methyl hydroxypropionic acid, cyclic di-esters of
hydroxypropionic acid, hydroxypropionic acid anhydride, or a
mixture thereof. Non-limiting examples of metal salts of
hydroxypropionic acid are sodium hydroxypropionate, potassium
hydroxypropionate, and calcium hydroxypropionate. Non-limiting
examples of alkyl esters of hydroxypropionic acid are methyl
hydroxypropionate, ethyl hydroxypropionate, butyl
hydroxypropionate, 2-ethylhexyl hydroxypropionate, or mixtures
thereof. A non-limiting example of cyclic di-esters of
hydroxypropionic acid is dilactide.
[0076] Hydroxypropionic acid can be in monomeric form or as
oligomers in an aqueous solution of hydroxypropionic acid,
hydroxypropionic acid derivatives, or mixtures thereof. In one
embodiment, the oligomers of the hydroxypropionic acid in an
aqueous solution of hydroxypropionic acid, hydroxypropionic acid
derivatives, or mixtures thereof are less than about 25 wt % based
on the total amount of hydroxypropionic acid, hydroxypropionic acid
derivatives, or mixtures thereof. In another embodiment, the
oligomers of the hydroxypropionic acid in an aqueous solution of
hydroxypropionic acid, hydroxypropionic acid derivatives, or
mixtures thereof are less than about 10 wt % based on the total
amount of hydroxypropionic acid, hydroxypropionic acid derivatives,
or mixtures thereof. In another embodiment, the oligomers of the
hydroxypropionic acid in an aqueous solution of hydroxypropionic
acid, hydroxypropionic acid derivatives, or mixtures thereof are
less than about 5 wt % based on the total amount of
hydroxypropionic acid, hydroxypropionic acid derivatives, or
mixtures thereof. In yet another embodiment, the hydroxypropionic
acid is in monomeric form in an aqueous solution of
hydroxypropionic acid, hydroxypropionic acid derivatives, or
mixtures thereof. The process steps to remove the oligomers from
the aqueous solution can be purification or diluting with water and
heating. In one embodiment, the heating step can involve heating
the aqueous solution of hydroxypropionic acid, hydroxypropionic
acid derivatives, or mixtures thereof at a temperature from about
50.degree. C. to about 100.degree. C. to remove the oligomers of
the hydroxypropionic acid. In another embodiment, the heating step
can involve heating the lactic acid aqueous solution at a
temperature from about 95.degree. C. to about 100.degree. C. to
remove the oligomers of the lactic acid and produce a monomeric
lactic acid aqueous solution comprising at least 95 wt % of lactic
acid in monomeric form based on the total amount of lactic acid. In
another embodiment, an about 88 wt % lactic acid aqueous solution
(e.g. from Purac Corp., Lincolnshire, Ill.) is diluted with water
to form an about 20 wt % lactic acid aqueous solution, to remove
the ester impurities that are produced from the intermolecular
condensation reaction. These esters can result in loss of product
due to their high boiling point and oligomerization in the
evaporation stage of the process. Additionally, these esters can
cause coking, catalyst deactivation, and reactor plugging. As the
water content decreases in the aqueous solution, the loss of feed
material to the catalytic reaction, due to losses in the
evaporation step, increases.
[0077] In one embodiment, the hydroxypropionic acid is lactic acid
or 2-methyl lactic acid. In another embodiment, the
hydroxypropionic acid is lactic acid. Lactic acid can be L-lactic
acid, D-lactic acid, or mixtures thereof. In one embodiment, the
hydroxypropionic acid derivative is methyl lactate. Methyl lactate
can be neat or in an aqueous solution.
[0078] Acrylic acid derivatives can be metal or ammonium salts of
acrylic acid, alkyl esters of acrylic acid, acrylic acid oligomers,
or a mixture thereof. Non-limiting examples of metal salts of
acrylic acid are sodium acrylate, potassium acrylate, and calcium
acrylate. Non-limiting examples of alkyl esters of acrylic acid are
methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl
acrylate, or mixtures thereof.
[0079] In one embodiment, the concentration of the hydroxypropionic
acid, hydroxypropionic acid derivatives, or mixtures thereof in the
aqueous solution is between about 5 wt % and about 50 wt %. In
another embodiment, the concentration of the hydroxypropionic acid,
hydroxypropionic acid derivatives, or mixtures thereof in the
aqueous solution is between about 10 wt % and about 25 wt %. In yet
another embodiment, the concentration of the hydroxypropionic acid,
hydroxypropionic acid derivatives, or mixtures thereof in the
aqueous solution is about 20 wt %.
[0080] The aqueous solution can be combined with an inert gas to
form an aqueous solution/gas blend. Non-limiting examples of the
inert gas are air, nitrogen, helium, argon, carbon dioxide, carbon
monoxide, steam, and mixtures thereof. The inert gas can be
introduced to the evaporating step separately or in combination
with the aqueous solution. The aqueous solution can be introduced
with a simple tube or through atomization nozzles. Non-limiting
examples of atomization nozzles include fan nozzles, pressure swirl
atomizers, air blast atomizers, two-fluid atomizers, rotary
atomizers, and supercritical carbon dioxide atomizers. In one
embodiment, the droplets of the aqueous solution are less than
about 500 .mu.m in diameter. In another embodiment, the droplets of
the aqueous solution are less than about 200 .mu.m in diameter. In
yet another embodiment, the droplets of the aqueous solution are
less than about 100 .mu.m in diameter.
[0081] In the evaporating step, the aqueous solution/gas blend is
heated to give a gaseous mixture. In one embodiment, the
temperature during the evaporating step is from about 165.degree.
C. to about 450.degree. C. In another embodiment, the temperature
during the evaporating step is from about 250.degree. C. to about
375.degree. C. In one embodiment, the gas hourly space velocity
(GHSV) in the evaporating step is from about 720 h.sup.-1 to 3,600
h.sup.-1. In another embodiment, the gas hourly space velocity
(GHSV) in the evaporating step is about 7,200 h.sup.-1. The
evaporating step can be performed at either atmospheric pressure or
higher pressure. In one embodiment, the evaporating step is
performed under a pressure from about 80 psig to about 550 psig. In
another embodiment, the evaporating step is performed under a
pressure from about 300 psig to about 400 psig. In yet another
embodiment, the evaporating step is performed under a pressure from
about 350 psig to about 375 psig. In one embodiment, the gaseous
mixture comprises from about 0.5 mol % to about 50 mol %
hydroxypropionic acid, hydroxypropionic acid derivatives, or
mixtures thereof. In another embodiment, the gaseous mixture
comprises from about 1 mol % to about 10 mol % hydroxypropionic
acid, hydroxypropionic acid derivatives, or mixtures thereof. In
another embodiment, the gaseous mixture comprises from about 1.5
mol % to about 3.5 mol % hydroxypropionic acid, hydroxypropionic
acid derivatives, or mixtures thereof. In another embodiment, the
gaseous mixture comprises about 2.5 mol % hydroxypropionic acid,
hydroxypropionic acid derivatives, or mixtures thereof.
[0082] The evaporating step can be performed in various types of
equipment, such as, but not limited to, plate heat exchanger, empty
flow reactor, and fixed bed flow reactor. Regardless of the type of
the reactor, in one embodiment, the reactor has an interior surface
comprising material selected from the group consisting of quartz,
borosilicate glass, silicon, hastelloy, inconel, manufactured
sapphire, stainless steel, and mixtures thereof. In another
embodiment, the reactor has an interior surface comprising material
selected from the group consisting of quartz, borosilicate glass,
and mixtures thereof. The evaporating step can be performed in a
reactor with the aqueous solution flowing down, or flowing up, or
flowing horizontally. In one embodiment, the evaporating step is
performed in a reactor with the aqueous solution flowing down.
Also, the evaporating step can be done in a batch form.
[0083] The gaseous mixture from the evaporating step is converted
to acrylic acid, acrylic acid derivatives, and mixture thereof by
contact it with a dehydration catalyst in the dehydrating step. The
dehydration catalyst can be selected from the group comprising
sulfates, phosphates, metal oxides, aluminates, silicates,
aluminosilicates (e.g., zeolites), arsenates, nitrates, vanadates,
niobates, tantalates, selenates, arsenatophosphates,
phosphoaluminates, phosphoborates, phosphocromates,
phosphomolybdates, phospho silicates, phosphosulfates,
phosphotungstates, and mixtures thereof, and others that may be
apparent to those having ordinary skill in the art. The catalyst
can contain an inert support that is constructed of a material
comprising silicates, aluminates, carbons, metal oxides, and
mixtures thereof. In one embodiment, the dehydrating step is
performed in a reactor, wherein the reactor has an interior surface
comprising material selected from the group consisting of quartz,
borosilicate glass, silicon, hastelloy, inconel, manufactured
sapphire, stainless steel, and mixtures thereof. In another
embodiment, the dehydrating step is performed in a reactor, wherein
the reactor has an interior surface comprising material selected
from the group consisting of quartz, borosilicate glass, and
mixtures thereof. In one embodiment, the temperature during the
dehydrating step is from about 150.degree. C. to about 500.degree.
C. In another embodiment, the temperature during the dehydrating
step is from about 300.degree. C. to about 450.degree. C. In one
embodiment, the GHSV in the dehydrating step is from about 720
h.sup.-1 to about 36,000 h.sup.-1. In another embodiment, the GHSV
in the dehydrating step is about 3,600 h.sup.-1. The dehydrating
step can be performed at higher than atmospheric pressure. In one
embodiment, the dehydrating step is performed under a pressure of
at least about 80 psig. In another embodiment, the dehydrating step
is performed under a pressure from about 80 psig to about 550 psig.
In another embodiment, the dehydrating step is performed under a
pressure from about 150 psig to about 500 psig. In yet another
embodiment, the dehydrating step is performed under a pressure from
about 300 psig to about 400 psig. The dehydrating step can be
performed in a reactor with the gaseous mixture flowing down,
flowing up, or flowing horizontally. In one embodiment, the
dehydrating step is performed in a reactor with the gaseous mixture
flowing down. Also, the dehydrating step can be done in a batch
form.
[0084] In one embodiment, the evaporating and dehydrating steps are
combined in a single step. In another embodiment, the evaporating
and dehydrating steps are performed sequentially in a single
reactor. In yet another embodiment, the evaporating and dehydrating
steps are performed sequentially in a tandem reactor.
[0085] In one embodiment, the selectivity of acrylic acid, acrylic
acid derivatives, and mixture thereof from hydroxypropionic acid,
hydroxypropionic acid derivatives, or mixtures thereof is at least
about 50%. In another embodiment, the selectivity of acrylic acid,
acrylic acid derivatives, and mixture thereof from hydroxypropionic
acid, hydroxypropionic acid derivatives, or mixtures thereof is at
least about 80%. In one embodiment, the selectivity of propanoic
acid from hydroxypropionic acid, hydroxypropionic acid derivatives,
or mixtures thereof is less than about 5%. In another embodiment,
the selectivity of propanoic acid from hydroxypropionic acid,
hydroxypropionic acid derivatives, or mixtures thereof is less than
about 1%. In one embodiment, the conversion of the hydroxypropionic
acid, hydroxypropionic acid derivatives, or mixtures thereof is
more than about 50%. In another embodiment, the conversion of the
hydroxypropionic acid, hydroxypropionic acid derivatives, or
mixtures thereof is more than about 80%.
[0086] In another embodiment of the present invention, a process
for converting hydroxypropionic acid, hydroxypropionic acid
derivatives, or mixtures thereof to acrylic acid, acrylic acid
derivatives, or mixtures thereof is provided. The process comprises
the following steps: a) providing an aqueous solution comprising
hydroxypropionic acid, hydroxypropionic acid derivatives, or
mixtures thereof, wherein the hydroxypropionic acid comprises
oligomers in the aqueous solution; b) heating the aqueous solution
at a temperature from about 50.degree. C. to about 100.degree. C.
to remove the oligomers of the hydroxypropionic acid and produce an
aqueous solution of monomeric hydroxypropionic acid; c) combining
the aqueous solution of monomeric hydroxypropionic acid with an
inert gas to form an aqueous solution/gas blend; d) evaporating the
aqueous solution gas/blend to produce a gaseous mixture; and e)
dehydrating the gaseous mixture by contacting the mixture with a
dehydration catalyst and producing the acrylic acid, acrylic acid
derivatives, or mixtures thereof.
[0087] In one embodiment, after the heating step, the concentration
of the oligomers of the hydroxypropionic acid in the aqueous
solution of monomeric of monomeric hydroxypropionic acid is less
than about 20 wt % based on the total amount of hydroxypropionic
acid, hydroxypropionic acid derivatives, or mixtures thereof. In
another embodiment, after the heating step, the concentration of
the oligomers of the hydroxypropionic acid in the aqueous solution
of monomeric of monomeric hydroxypropionic acid is less than about
5 wt % based on the total amount of hydroxypropionic acid,
hydroxypropionic acid derivatives, or mixtures thereof.
[0088] In another embodiment of the present invention, a process
for converting hydroxypropionic acid, hydroxypropionic acid
derivatives, or mixtures thereof to acrylic acid, acrylic acid
derivatives, and mixture thereof is provided. The process comprises
the following steps: a) providing an aqueous solution comprising
hydroxypropionic acid, hydroxypropionic acid derivatives, or
mixtures thereof, wherein the hydroxypropionic acid is in monomeric
form in the aqueous solution; b) combining the aqueous solution
with an inert gas to form an aqueous solution/gas blend; c)
evaporating the aqueous solution/gas blend to produce a gaseous
mixture; d) dehydrating the gaseous mixture by contacting the
mixture with a dehydration catalyst producing acrylic acid, and/or
acrylates; and e) cooling the acrylic acid, acrylic acid
derivatives, and mixture thereof at a GHSV of more than about 360
h.sup.-1.
[0089] The stream of acrylic acid, acrylic acid derivatives, and
mixture thereof produced in the dehydrating step is cooled to give
an aqueous acrylic acid composition as the product stream. The time
required to cool stream of the acrylic acid, acrylic acid
derivatives, or mixtures thereof must be controlled to reduce the
decomposition of acrylic acid to ethylene and polymerization. In
one embodiment, the GHSV of the acrylic acid, acrylic acid
derivatives, and mixture thereof in the cooling step is more than
about 720 h.sup.-1.
[0090] In another embodiment of the present invention, a process
for converting lactic acid to acrylic acid is provided. The process
comprises the following steps: a) diluting an about 88 wt % lactic
acid aqueous solution with water to form an about 20 wt % lactic
acid aqueous solution; b) heating the about 20 wt % lactic acid
aqueous solution at a temperature of about 95.degree. C. to about
100.degree. C. to remove oligomers of the lactic acid, producing a
monomeric lactic acid solution comprising at least about 95 wt % of
the lactic acid in monomeric form based on the total amount of
lactic acid; c) combining the monomeric lactic acid solution with
nitrogen to form an aqueous solution/gas blend; d) evaporating the
aqueous solution/gas blend in a reactor with inside surface of
borosilicate glass at a GHSV of about 7,200 h.sup.-1 at a
temperature from about 300.degree. C. to about 350.degree. C. to
produce a gaseous mixture comprising about 2.5 mol % lactic acid
and about 50 mol % water; e) dehydrating the gaseous mixture in a
reactor with inside surface of borosilicate glass at a GHSV of
about 3,600 h.sup.-1 at a temperature of 350.degree. C. to about
425.degree. C. by contacting the mixture with a dehydration
catalyst under a pressure of about 360 psig, producing the acrylic
acid; and f) cooling the acrylic acid at a GHSV from about 360
h.sup.-1 to about 36,000 h.sup.-1.
[0091] In another embodiment of the present invention, a process
for converting hydroxypropionic acid, derivatives of
hydroxypropionic acid, and mixtures thereof to acrylic acid,
acrylic acid derivatives, or mixtures thereof is provided. The
process comprises the following steps: a) providing an aqueous
solution comprising hydroxypropionic acid, hydroxypropionic acid
derivatives, or mixtures thereof, wherein the hydroxypropionic acid
is in monomeric form in the aqueous solution, and wherein the
hydroxypropionic acid, hydroxypropionic acid derivatives, or
mixtures thereof comprise from about 10 wt % to about 25 wt % of
the aqueous solution; b) combining the aqueous solution with an
inert gas to form an aqueous solution/gas blend; c) evaporating the
aqueous solution/gas blend to produce a gaseous mixture; and d)
dehydrating the gaseous mixture by contacting the mixture with a
dehydration catalyst producing acrylic acid, acrylic acid
derivatives, or mixtures thereof.
[0092] In another embodiment of the present invention, a process
for converting alkyl lactates to acrylic acid, acrylic acid
derivatives, or mixtures thereof is provided. The process comprises
the following steps: a) providing alkyl lactates or a solution
comprising alkyl lactates and a solvent;
[0093] b) combining said alkyl lactates or said solution comprising
said alkyl lactates and said solvent with an inert gas to form a
liquid/gas blend; c) evaporating said liquid/gas blend to produce a
gaseous mixture; and d) dehydrating said gaseous mixture by
contacting said gaseous mixture with a dehydration catalyst under a
pressure of at least about 80 psig, producing acrylic acid, acrylic
acid derivatives, or mixtures thereof.
[0094] In one embodiment, alkyl lactates are selected from the
group consisting of methyl lactate, ethyl lactate, butyl lactate,
2-ethylhexyl lactate, and mixtures thereof. In another embodiment,
the solvent is selected from the group consisting of water,
methanol, ethanol, butanol, 2-ethylhexanol, isobutanol, isooctyl
alcohol, and mixtures thereof.
[0095] In another embodiment of the present invention, the
dehydration occurs in the liquid phase, at least partially. In yet
another embodiment, the dehydration occurs in the aqueous phase, at
least partially. In the case of liquid phase dehydration, the
apparatus has to be pressurized to ensure that all major components
are in the liquid phase. The liquid-phase dehydration can be
conducted by using various methods, known to those skilled in the
art, such as, by way of example and not limitation, fixed bed
reactor, single-stage stirred tank reactor, multi-stage stirred
tank reactor, multi-stage distillation column, and combinations
thereof. These methods may be conducted batch-wise or
continuously.
[0096] In one embodiment, the dehydration occurs in the aqueous
phase, at least partially, and the pH of the reaction is between
about 3 and about 8. In another embodiment, the pH of the reaction
in the aqueous phase is between about 4 and about 7. In yet another
embodiment, the pH of the reaction in the aqueous phase is between
about 5 and about 6.
[0097] In one embodiment of the present invention, the dehydration
occurs in the gas phase, at least partially. The gas-phase
dehydration can be conducted by using various methods, known to
those skilled in the art, such as, by way of example and not
limitation, fixed bed reactor, moving bed reactor, fluidized bed
reactor, and combinations thereof. These methods may be conducted
batch-wise or continuously.
III Catalysts for the Conversion of Hydroxypropionic Acid or its
Derivatives to Acrylic Acid or its Derivatives
[0098] In one embodiment, the catalyst includes: (a) monohydrogen
monophosphate and dihydrogen monophosphate anions described by
formulae (I) and (II):
[HPO.sub.4].sup.2- (I),
[H.sub.2PO.sub.4].sup.- (II),
and (b) at least two different cations, wherein the catalyst is
essentially neutrally charged; and further, wherein the molar ratio
of said monohydrogen monophosphate anion to said dihydrogen
monophosphate anion in the catalyst is between about 0.1 and about
10. In another embodiment, the molar ratio of monohydrogen
monophosphate anion to dihydrogen monophosphate anion is between
about 0.2 and about 5. In yet another embodiment, the molar ratio
of monohydrogen monophosphate anion to dihydrogen monophosphate
anion is about 1.
[0099] In one embodiment of the present invention, the catalyst
includes the monophosphate salts described by the formulae (III)
and (IV):
M.sup.IIHPO.sub.4 (III),
M.sup.IH.sub.2PO.sub.4 (IV), and [0100] wherein M.sup.I is a
monovalent cation and M.sup.II is a divalent cation. In another
embodiment, the molar ratio of M.sup.IIHPO.sub.4 to
M.sup.IH.sub.2PO.sub.4 is between about 0.1 and about 10. In
another embodiment, the molar ratio of M.sup.IIHPO.sub.4 to
M.sup.IH.sub.2PO.sub.4 is between about 0.2 and about 5. In yet
another embodiment, the molar ratio of M.sup.IIHPO.sub.4 to
M.sup.IH.sub.2PO.sub.4 is about 1.
[0101] In one embodiment of the present invention, the catalyst
includes a monophosphate salt described by the formula (V):
M.sup.II.sub.2-.alpha.M.sup.I.sub..alpha.H.sub..alpha.(HPO.sub.4).sub.2
(V),
wherein M.sup.I is a monovalent cation and M.sup.II is a divalent
cation; and wherein a is greater than about 0.2 and smaller than
about 1.8. In another embodiment of the present invention, .alpha.
is about 1.
[0102] In another embodiment, the monohydrogen monophosphate anion
described by formula (I) is substituted by one or more phosphate
anions described by the formula
[H.sub.(1-.beta.)P.sub.(1+.beta.)O.sub.(4+3.beta.)].sup.2(1+.beta.)-,
wherein .beta. is greater or equal to zero and less or equal to
1.
[0103] In another embodiment, the dihydrogen monophosphate anion
described by formula (II) is substituted by one or more phosphate
anions described by the formula
[H.sub.2(-.beta.)PO.sub.(4-.beta.)].sup.-, wherein .beta. is
greater or equal to zero and less or equal to 1.
[0104] In one embodiment, the catalyst comprises: (a) at least one
condensed phosphate anion selected from the group consisting of
formulae (VI), (VII), and (VIII),
[P.sub.nO.sub.3n+1].sup.(n+2)- (VI)
[P.sub.n.sup.O.sub.3n].sup.n- (VII)
[P.sub.(2m+n)O.sub.(5m+3n)].sup.n- (VIII)
wherein n is at least 2 and m is at least 1, and (b) at least two
different cations, wherein the catalyst is essentially neutrally
charged, and further, wherein the molar ratio of phosphorus to the
at least two different cations is between about 0.7 and about
1.7.
[0105] The anions defined by formulae (VI), (VII), and (VIII) are
also referred to as polyphosphates (or oligophosphates),
cyclophosphates, and ultraphosphates, respectively.
[0106] In another embodiment, the catalyst comprises: (a) at least
one condensed phosphate anion selected from the group consisting of
formulae (VI) and (VII),
[P.sub.nO.sub.3n+1].sup.(n+2)- (VI)
[P.sub.nO.sub.3n].sup.n- (VII)
wherein n is at least 2, and (b) at least two different cations,
wherein the catalyst is essentially neutrally charged, and further,
wherein the molar ratio of phosphorus to the at least two different
cations is between about 0.7 and about 1.7.
[0107] In one embodiment, the molar ratio of phosphorus to the
cations in the catalyst is between about 0.7 and about 1.7; in
another embodiment, the molar ratio of phosphorus to the cations in
the catalyst is between about 0.8 and about 1.3; and in yet another
embodiment, the molar ratio of phosphorus to the cations in the
catalyst is about 1.
[0108] In one embodiment, the at least two different cations
comprise (a) at least one monovalent cation, and (b) at least one
polyvalent cation. In another embodiment, the molar ratio of the
monovalent cations to the polyvalent cations is between about 0.1
and about 10. In yet another embodiment, the molar ratio of the
monovalent cations to the polyvalent cations is between about 0.5
and about 5. In a further embodiment of the present invention, the
molar ratio of the monovalent cations to the polyvalent cations is
about 1.
[0109] In another embodiment, the polyvalent cation is selected
from the group consisting of divalent cations, trivalent cations,
tetravalent cations, pentavalent cations, and mixtures thereof.
Non-limiting examples of monovalent cations are H.sup.+, Li.sup.+,
Na.sup.+, K.sup.+, Rb.sup.+, Cs.sup.+, Ag.sup.+, Rb.sup.+,
Tl.sup.+, and mixtures thereof. In one embodiment, the monovalent
cation is selected from the group consisting of Li.sup.+, Na.sup.+,
K.sup.+, Rb.sup.+, Cs.sup.+, and mixtures thereof; in another
embodiment, the monovalent cation is Na.sup.+ or K.sup.+; and in
yet another embodiment, the monovalent cation is K.sup.+.
Non-limiting examples of polyvalent cations are cations of the
alkaline earth metals (i.e., Be, Mg, Ca, Sr, Ba, and Ra),
transition metals (e.g. Y, Ti, Zr, V, Nb, Cr, Mo, Mn, Re, Fe, Ru,
Co, Rh, Ni, Pd, Pt, Cu, Ag, and Au), poor metals (e.g. Zn, Ga, Si,
Ge, B, Al, In, Sb, Sn, Bi, and Pb), lanthanides (e.g. La and Ce),
and actinides (e.g. Ac and Th). In one embodiment, the polyvalent
cation is selected from the group consisting of Be.sup.2+,
Mg.sup.2+, Ca.sup.2+, Sr.sup.2+, Ba.sup.2+, Mn.sup.2+, Fe.sup.2+,
Co.sup.2+, Ni.sup.2+, CU.sup.2+, Zn.sup.2+, Cd.sup.2+, Sn.sup.2+,
Pb.sup.2+, Ti.sup.3+, Cr.sup.3+, Mn.sup.3+, Fe.sup.3+, Al.sup.3+,
Ga.sup.3+, Y.sup.3+, In.sup.3+, Sb.sup.3+, Bi.sup.3+, Si.sup.4+,
Ti.sup.4+, V.sup.4+, Ge.sup.4+, Mo.sup.4+, Pt.sup.4+, V.sup.5+,
Nb.sup.5+, Sb.sup.5+, and mixtures thereof. In one embodiment, the
polyvalent cation is selected from the group consisting of
Ca.sup.2+, Ba.sup.2+, Cu.sup.2+, Mn.sup.2+, Mn.sup.3+, and mixtures
thereof; in another embodiment, the polyvalent cation is selected
from the group consisting of Ca.sup.2+, Ba.sup.2+, Mn.sup.3+, and
mixtures thereof; and in yet another embodiment, the polyvalent
cation is Ba.sup.2+.
[0110] The catalyst can include cations: (a) H.sup.+, Li.sup.+,
Na.sup.+, K.sup.+, Rb.sup.+, Cs.sup.+, or mixtures thereof; and (b)
Be.sup.2+, Mg.sup.2+, Ca.sup.2+, Sr.sup.2+, Ba.sup.2+, Mn.sup.2+,
Fe.sup.2+, Co.sup.2+, Ni.sup.2+, Cu.sup.2+, Zn.sup.2+, Cd.sup.2+,
Sn.sup.2+, Pb.sup.2+, Ti.sup.3+, Cr.sup.3+, Mn.sup.3+, Fe.sup.3+,
Al.sup.3+, Ga.sup.3+, Y.sup.3+, In.sup.3+, Sb.sup.3+, Bi.sup.3+,
Si.sup.4+, Ti.sup.4+, V.sup.4+, Ge.sup.4+, Mo.sup.4+, Pt.sup.4+,
V.sup.5+, Nb.sup.5+, Sb.sup.5+, or mixtures thereof. In one
embodiment the catalyst comprises Li.sup.+, Na.sup.+, or K.sup.+ as
monovalent cation, and Ca.sup.2+, Ba.sup.2+, or Mn.sup.3+ as
polyvalent cation; in another embodiment, the catalyst comprises
Na.sup.+ or K.sup.+ as monovalent cation, and Ca.sup.2+ or
Ba.sup.2+ as polyvalent cation; and in yet another embodiment, the
catalyst comprises K.sup.+ as the monovalent cation and Ba.sup.2+
as the polyvalent cation.
[0111] In one embodiment, the catalyst comprises
Ba.sub.2-x-sK.sub.2xH.sub.2sP.sub.2O.sub.7 and (KPO.sub.3), wherein
x and s are greater or equal to 0 and less than about 0.5 and n is
a positive integer. In another embodiment, the catalyst comprises
Ca.sub.2-x-sK.sub.2xH.sub.2sP.sub.2O.sub.7 and (KPO.sub.3).sub.n,
wherein x and s are greater or equal to 0 and less than about 0.5
and n is at least 2. In yet another embodiment, the catalyst
comprises Mm.sub.1-x-sK.sub.1+3xH.sub.3sP.sub.2O.sub.7 or
Mn.sub.1-x-sK.sub.2+2xH.sub.2sP.sub.2O.sub.7 and (KPO.sub.3)
wherein x and s are greater or equal to 0 and less than about 0.5
and n is at least 2. In another embodiment, the catalyst comprises
any blend of Ba.sub.2-x-sK.sub.2xH.sub.2sP.sub.2O.sub.7,
Ca.sub.2-x-sK.sub.2xH.sub.2sP.sub.2O.sub.7,
Mn.sub.1-x-sK.sub.1+3xH.sub.3sP.sub.2O.sub.7 or
Mn.sub.1-sK.sub.2+2xH.sub.2sP.sub.2O.sub.7; and (KPO.sub.3).sub.n,
wherein x and s are greater or equal to 0 and less than about 0.5
and n is at least 2.
[0112] In one embodiment, the catalyst includes: (a) monohydrogen
monophosphate and dihydrogen monophosphate anions described by
formulae (I) and (II):
[HPO.sub.4].sup.2- (I),
[H.sub.2PO.sub.4].sup.- (II),
and (b) one cation, wherein the catalyst is essentially neutrally
charged; and further, wherein the molar ratio of said monohydrogen
monophosphate anion to said dihydrogen monophosphate anion in the
catalyst is between about 0.1 and about 10. In another embodiment,
the molar ratio of monohydrogen monophosphate anion to dihydrogen
monophosphate anion is between about 0.2 and about 5. In yet
another embodiment, the molar ratio of monohydrogen monophosphate
anion to dihydrogen monophosphate anion is about 1.
[0113] In one embodiment, the catalyst comprises: (a) at least two
different condensed phosphate anions selected from the group
consisting of formulae (VI), (VII), and (VIII),
[P.sub.nO.sub.3n+1].sup.(n+2)- (VI)
[P.sub.nO.sub.3n].sup.n- (VII)
[P.sub.(2m+n)O.sub.(5m+3n)].sup.n- (VIII)
wherein n is at least 2 and m is at least 1, and (b) one cation,
wherein the catalyst is essentially neutrally charged, and further,
wherein the molar ratio of phosphorus to the cation is between
about 0.5 and about 4.0. In another embodiment, the molar ratio of
phosphorus to the cation is between about t/2 and about t, wherein
t is the charge of the cation.
[0114] The catalyst can include an inert support that is
constructed of a material comprising silicates, aluminates,
carbons, metal oxides, and mixtures thereof. Alternatively, the
carrier is inert relative to the reaction mixture expected to
contact the catalyst. In the context of the reactions expressly
described herein, in one embodiment the carrier is a low surface
area silica or zirconia. When present, the carrier represents an
amount of about 5 wt % to about 98 wt %, based on the total weight
of the catalyst. Generally, a catalyst that includes an inert
support can be made by one of two exemplary methods: impregnation
or co-precipitation. In the impregnation method, a suspension of
the solid inert support is treated with a solution of a
pre-catalyst, and the resulting material is then activated under
conditions that will convert the pre-catalyst to a more active
state. In the co-precipitation method, a homogenous solution of the
catalyst ingredients is precipitated by the addition of additional
ingredients.
[0115] In another embodiment, the catalyst can be sulfate salts;
phosphate salts; mixtures of sulfate and phosphate salts; bases;
zeolites or modified zeolites; metal oxides or modified metal
oxides; supercritical water, or mixtures thereof.
IV Catalyst Preparation Methods
[0116] In one embodiment, the method of preparing the catalyst
includes mixing at least two different phosphorus containing
compounds, wherein each said compound is described by one of the
formulae (IX) to (XXX), or any of the hydrated forms of said
formulae:
M.sup.I.sub.y(H.sub.3-yPO.sub.4) (IX)
M.sup.II.sub.y(H.sub.3-yPO.sub.4).sub.2 (X)
M.sup.III.sub.y(H.sub.3-yPO.sub.4).sub.3 (XI)
M.sup.IV.sub.y(H.sub.3-yPO.sub.4).sub.4 (XII)
(NH.sub.4).sub.y(H.sub.3-yPO.sub.4) (XIII)
M.sup.II.sub.a(OH).sub.b(PO.sub.4).sub.c (XIV)
M.sup.III.sub.d(OH).sub.e(PO.sub.4).sub.f (XV)
M.sup.IIM.sup.IPO.sub.4 (XVI)
M.sup.IIIM.sup.1.sub.3(PO.sub.4).sub.2 (XVII)
M.sup.IV.sub.2M.sup.I(PO.sub.4).sub.3 (XVIII)
M.sup.I.sub.zH.sub.4-zP.sub.2O.sub.7 (XIX)
M.sup.II.sub.vH.sub.(4-2v)P.sub.2O.sub.7 (XX)
M.sup.IVP.sub.2O.sub.7 (XXI)
(NH.sub.4).sub.zH.sub.4-zP.sub.2O.sub.7 (XXII)
M.sup.IIIM.sup.IP.sub.2O.sub.7 (XXIII)
M.sup.IH.sub.w(PO.sub.3).sub.(1+w) (XXIV)
M.sup.IIH.sub.w(PO.sub.3).sub.(2+w) (XXV)
M.sup.IIIH.sub.w(PO.sub.3).sub.(3+w) (XXVI)
M.sup.IVH.sub.w(PO.sub.3).sub.(4+w) (XXVII)
M.sup.II.sub.gM.sup.I.sub.h(PO.sub.3).sub.i (XXVIII)
M.sup.III.sub.jM.sup.I.sub.k(PO.sub.3).sub.l (XXIX)
P.sub.2O.sub.5 (XXX)
wherein M.sup.I is a monovalent cation; wherein M.sup.II is a
divalent cation; wherein M.sup.III is a trivalent cation; wherein
M.sup.IV is a tetravalent cation; wherein y is 0, 1, 2, or 3;
wherein z is 0, 1, 2, 3, or 4; wherein v is 0, 1, or 2; wherein w
is 0 or any positive integer; and wherein a, b, c, d, e, f, g, h,
i, j, k, and l are any positive integers, such that the equations:
2a=b+3c, 3d=e+3f, i=2g+h, and 1=3j+k are satisfied. In another
embodiment, the method of preparing the catalyst includes heating
the phosphorus-containing compounds after mixing. In another
embodiment, the method of preparing the catalyst includes
contacting the phosphorus-containing compounds after mixing, with a
gaseous mixture comprising water.
[0117] In one embodiment, the catalyst is prepared by the steps
including mixing one or more phosphorus containing compounds of
formula (IX), wherein y is equal to 1, and one or more phosphorus
containing compounds of formula (X), wherein y is equal to 2. In
another embodiment, the catalyst is prepared by the steps including
mixing M.sup.IH.sub.2PO.sub.4 and M.sup.IIHPO.sub.4. In one
embodiment, M.sup.I is K.sup.+ and M.sup.II is Ca.sup.2+, i.e., the
catalyst is prepared by mixing KH.sub.2PO.sub.4 and CaHPO.sub.4; or
M.sup.I is K and M.sup.II is Ba.sup.2+, i.e., the catalyst is
prepared by the steps including mixing KH.sub.2PO.sub.4 and
BaHPO.sub.4.
[0118] In one embodiment, the catalyst is prepared by the steps
including mixing one or more phosphorus containing compound of
formula (IX), wherein y is equal to 1, one or more phosphorus
containing compounds of formula (XX), wherein v is equal to 2. In
another embodiment, the catalyst is prepared by the steps including
mixing M.sup.IH.sub.2PO.sub.4 and M.sup.II.sub.2P.sub.2O.sub.7. In
one embodiment, M.sup.I is K.sup.+ and M.sup.II is Ca.sup.2+, i.e.,
the catalyst is prepared by mixing KH.sub.2PO.sub.4 and
Ca.sub.2P.sub.2O.sub.7; or M.sup.I is K.sup.+ and M.sup.II is
Ba.sup.2+, i.e., the catalyst is prepared by the steps including
mixing KH.sub.2PO.sub.4 and Ba.sub.2P.sub.2O.sub.7.
[0119] In another embodiment, the catalyst is prepared by the steps
including mixing one or more phosphorus-containing compounds of
formula (X), wherein said y is equal to 2, and one or more
phosphorus-containing compound of formula (XXIV), wherein said w is
equal to 0. In another embodiment, the phosphorus-containing
compounds are (KPO.sub.3).sub.n and BaHPO.sub.4 or CaHPO.sub.4;
wherein n is an integer greater than 2.
[0120] In yet another embodiment, the catalyst is prepared by the
steps including mixing one or more phosphorus-containing compounds
of formula (XX), wherein said v is equal to 2, and one or more
phosphorus-containing compound of formula (XXIV), wherein said w is
equal to 0. In another embodiment, the phosphorus-containing
compounds are (KPO.sub.3).sub.n and Ba.sub.2P.sub.2O.sub.7 or
Ca.sub.2P.sub.2O.sub.7; wherein n is an integer greater than 2.
[0121] In another embodiment, the molar ratio of phosphorus to the
cations in the catalyst is between about 0.7 and about 1.7; in yet
another embodiment, the molar ratio of phosphorus to the cations in
the catalyst is between about 0.8 and about 1.3; and in another
embodiment, the molar ratio of phosphorus to the cations in the
catalyst is about 1.
[0122] In another embodiment, the method of preparing the catalyst
includes mixing (a) at least one phosphorus containing compound,
wherein each said compound is described by one of the formulae (IX)
to (XXX), or any of the hydrated forms of said formulae:
M.sup.I.sub.y(H.sub.3-yPO.sub.4) (IX)
M.sup.II.sub.y (H.sub.3-yPO.sub.4).sub.2 (X)
M.sup.III.sub.y(H.sub.3-yPO.sub.4).sub.3 (XI)
M.sup.IV.sub.y(H.sub.3-yPO.sub.4).sub.4 (XII)
(NH.sub.4).sub.y(H.sub.3-yPO.sub.4) (XIII)
M.sup.II.sub.a(OH).sub.b(PO.sub.4).sub.c (XIV)
M.sup.III.sub.d(OH).sub.e(PO).sub.f (XV)
M.sup.IIM.sup.IPO.sub.4 (XVI)
M.sup.IIIM.sup.I.sub.3(PO.sub.4).sub.2 (XVII)
M.sup.IV.sub.2M.sup.I(PO.sub.4).sub.3 (XVIII)
M.sup.I.sub.zH.sub.4-zP.sub.2O.sub.7 (XIX)
M.sup.II.sub.vH.sub.(4-2v)P.sub.2O.sub.7 (XX)
M.sup.IVP.sub.2O.sub.7 (XXI)
(NH.sub.4).sub.zH.sub.4-zP.sub.2O.sub.7 (XXII)
M.sup.IIIM.sup.IP.sub.2O.sub.7 (XXIII)
M.sup.IH.sub.w(PO.sub.3).sub.1+w) (XXIV)
M.sup.IIH.sub.w(PO.sub.3).sub.(2+w) (XXV)
M.sup.IIIH.sub.w(PO.sub.3).sub.(3+w) (XXVI)
M.sup.IVH.sub.w(PO.sub.3).sub.(4+w) (XXVII)
M.sup.II.sub.gM.sup.I.sub.h(PO.sub.3).sub.i (XXVIII)
M.sup.III.sub.jM.sup.I.sub.k(PO.sub.3).sub.l (XXIX)
P.sub.2O.sub.5 (XXX)
wherein y is 0, 1, 2, or 3; wherein z is 0, 1, 2, 3, or 4; wherein
v is 0, 1, or 2; wherein w is 0 or any positive integer; and
wherein a, b, c, d, e, f, g, h, i, j, k, and l are any positive
integers, such that the equations: 2a=b+3c, 3d=e+3f, i=2g+h, and
1=3j+k are satisfied, and (b) at least one non-phosphorus
containing compound selected from the group consisting of nitrate
salts, carbonate salts, acetate salts, metal oxides, chloride
salts, sulfate salts, and metal hydroxides, wherein each said
compound is described by one of the formulae (XXVI) to (L), or any
of the hydrated forms of said formulae:
M.sup.INO.sub.3 (XXXI)
M.sup.II(NO.sub.3).sub.2 (XXXII)
M.sup.III(NO.sub.3).sub.3 (XXXIII)
M.sup.I.sub.2CO.sub.3 (XXXIV)
M.sup.IICO.sub.3 (XXXV)
M.sup.III.sub.2(CO.sub.3).sub.3 (XXXVI)
(CH.sub.3COO)M.sup.I (XXXVII)
(CH.sub.3COO).sub.2M.sup.II (XXXVIII)
(CH.sub.3COO).sub.3M.sup.III (XXXIX)
(CH.sub.3COO).sub.4M.sup.IV (XL)
M.sup.I.sub.2O (XLI)
M.sup.IIO (XLII)
M.sup.IIIO.sub.3 (XLIII)
M.sup.IVO.sub.2 (XLIV)
M.sup.ICl (XLV)
M.sup.IICl.sub.2 (XLVI)
M.sup.IIICl.sub.3 (XLVII)
M.sup.IVCl.sub.4 (XLVIII)
M.sup.I.sub.2SO.sub.4 (XLIX)
M.sup.IISO.sub.4 (L)
M.sup.III.sub.2(SO.sub.4).sub.3 (LI)
M.sup.IV(SO.sub.4).sub.2 (LII)
M.sup.IOH (LIII)
M.sup.II(OH) (LIV)
M.sup.III(OH).sub.3 (LV).
[0123] In another embodiment, the non-phosphorus containing
compounds can be selected from the group consisting of carboxylic
acid-derived salts, halide salts, metal acetylacetonates, and metal
alkoxides.
[0124] In another embodiment, the method of preparing the catalyst
includes contacting the phosphorus-containing and the
non-phosphorus-containing compounds after mixing, with a gaseous
mixture comprising water.
[0125] In one embodiment of the present invention, the molar ratio
of phosphorus to the cations in the catalyst is between about 0.7
and about 1.7; in another embodiment, the molar ratio of phosphorus
to the cations in the catalyst is between about 0.8 and about 1.3;
and in yet another embodiment, the molar ratio of phosphorus to the
cations in the catalyst is about 1.
[0126] In another embodiment of the present invention, the catalyst
is prepared by mixing and heating one or more phosphorus containing
compounds of formulae (IX) to (XXX) or their hydrated forms, and
one or more nitrate salts of formulae (XXXI) to (XXXIII) or their
hydrated forms. In another embodiment of the present invention, the
catalyst is prepared by mixing and heating one or more phosphorus
containing compounds of formula (IX) and one or more nitrate salts
of formula (XXXII). In a further embodiment of the present
invention, the catalyst is prepared by mixing and heating a
phosphorus containing compound of formula (IX) wherein y is equal
to 2, a phosphorus containing compound of formula (IX) wherein y is
equal to 0 (i.e., phosphoric acid), and a nitrate salt of formula
(XXXII). In yet another embodiment of the present invention, the
catalyst is prepared by mixing and heating K.sub.2HPO.sub.4,
H.sub.3PO.sub.4, and Ba(NO.sub.3).sub.2. In yet another embodiment,
the catalyst is prepared by mixing and heating K.sub.2HPO.sub.4,
H.sub.3PO.sub.4, and Ca(NO.sub.3).sub.2.
[0127] In one embodiment of the present invention, the catalyst is
prepared by mixing and heating one or more phosphorus containing
compounds of formula (IX) and one or more nitrate salts of formula
(XXXIII). In a further embodiment of the present invention, the
catalyst is prepared by mixing and heating a phosphorus containing
compound of formula (IX) wherein y is equal to 2, a phosphorus
containing compound of formula (IX) wherein y is equal to 0 (i.e.,
phosphoric acid), and a nitrate salt of formula (XXXIII). In yet
another embodiment of the present invention, the catalyst is
prepared by mixing and heating K.sub.2HPO.sub.4, H.sub.3PO.sub.4,
and Mn(NO.sub.3).sub.24H.sub.2O.
[0128] In one embodiment of the present invention, the catalyst is
prepared by mixing and heating one or more phosphorus containing
compounds of formula (X) and one or more nitrate salts of formula
(XXXI). In another embodiment of the present invention, the
catalyst is prepared by mixing and heating a phosphorus containing
compound of formula (X) wherein y is equal to 2, a phosphorus
containing compound of formula (X) wherein y is equal to 0 (i.e.,
phosphoric acid), and a nitrate salt of formula (XXXI). In yet
another embodiment of the present invention, the catalyst is
prepared by mixing and heating BaHPO.sub.4, H.sub.3PO.sub.4, and
KNO.sub.3. In another embodiment, the catalyst is prepared by
mixing and heating CaHPO.sub.4, H.sub.3PO.sub.4, and KNO.sub.3.
[0129] In one embodiment of this invention, the catalyst is
prepared by mixing and heating one or more phosphorus containing
compounds of formula (X), one or more phosphorus containing
compounds of formula (XX), and one or more nitrate salts of formula
(XXXI). In a further embodiment of this invention, the catalyst is
prepared by mixing and heating a phosphorus containing compound of
formula (X), wherein y is equal to 0 (i.e., phosphoric acid); a
phosphorus containing compound of formula (XX), wherein v is equal
to 2; and a nitrate salt of formula (XXXI). In another embodiment
of the present invention, the catalyst is prepared by mixing and
heating H.sub.3PO.sub.4, Ca.sub.2P.sub.2O.sub.7, and KNO.sub.3. In
yet another embodiment, the catalyst is prepared by mixing and
heating H.sub.3PO.sub.4, Ba.sub.2P.sub.2O.sub.7, and KNO.sub.3.
[0130] In another embodiment of this invention, the catalyst is
prepared by mixing and heating one or more phosphorus containing
compounds of formula (XI) and one or more nitrate salts of formula
(XXXI). In another embodiment of this invention, the catalyst is
prepared by mixing and heating a phosphorus containing compound of
formula (XI), wherein y is equal to 3; a phosphorus containing
compound of formula (XI), wherein y is equal to 0 (i.e., phosphoric
acid);
[0131] and a nitrate salt of formula (XXXI). In yet another
embodiment of this invention, the catalyst is prepared by mixing
and heating MnPO.sub.4qH.sub.2O, H.sub.3PO.sub.4, and
KNO.sub.3.
[0132] In one embodiment of this invention, the catalyst is
prepared by mixing and heating one or more phosphorus containing
compounds of formula (IX), one or more phosphorus containing
compounds of formula (XIV), and one or more nitrate salts of
formula (XXXII). In another embodiment of this invention, the
catalyst is prepared by mixing and heating a phosphorus containing
compound of formula (IX), wherein y is equal to 2; a phosphorus
containing compound of formula (IX), wherein y is equal to 0 (i.e.,
phosphoric acid); a phosphorus containing compound of formula
(XIV), wherein a is equal to 2, b is equal to 1, and c is equal to
1; and a nitrate salt of formula (XXXII). In yet another embodiment
of this invention, the catalyst is prepared by mixing and heating
K.sub.2HPO.sub.4, H.sub.3PO.sub.4, Cu.sub.2(OH)PO.sub.4, and
Ba(NO.sub.3).sub.2.
[0133] In one embodiment of this invention, the catalyst is
prepared by mixing and heating one or more phosphorus containing
compounds of formula (X), one or more phosphorus containing
compounds of formula (XIV), and one or more nitrate salts of
formula (XXXI). In another embodiment of this invention, the
catalyst is prepared by mixing and heating a phosphorus containing
compound of formula (X), wherein y is equal to 3; a phosphorus
containing compound of formula (X), wherein y is equal to 0 (i.e.,
phosphoric acid); a phosphorus containing compound of formula
(XIV), wherein a is equal to 2, b is equal to 1, and c is equal to
1; and a nitrate salt of formula (XXXI). In yet another embodiment,
the catalyst is prepared by mixing and heating
Ba.sub.3(PO.sub.4).sub.2, H.sub.3PO.sub.4, Cu.sub.2(OH)PO.sub.4,
and KNO.sub.3.
[0134] In one embodiment of the present invention, the catalyst is
prepared by mixing and heating one or more phosphorus containing
compounds described by one of the formulae (IX) to (XXX) or any of
the hydrated forms, and one or more carbonate salts described by
one of the formulae (XXXIV) to (XXXVI) or any of the hydrated
forms.
[0135] In one embodiment of the present invention, the catalyst is
prepared by mixing and heating one or more phosphorus containing
compounds described by one of the formulae (IX) to (XXX) or any of
the hydrated forms, and one or more acetate salts described by one
of the formulae (XXXVII) to (XL), any other organic acid-derived
salts, or any of the hydrated forms.
[0136] In one embodiment of the present invention, the catalyst is
prepared by mixing and heating one or more phosphorus containing
compounds described by one of the formulae (IX) to (XXX) or any of
the hydrated forms, and one or more metal oxides described by one
of the formulae (XLI) to (XLIV) or any of the hydrated forms. In
one embodiment of the present invention, the catalyst is prepared
by mixing and heating one or more phosphorus containing compounds
described by one of the formulae (IX) to (XXX) or any of the
hydrated forms, and one or more chloride salts described by one of
the formulae (XLV) to (XLVIII), any other halide salts, or any of
the hydrated forms.
[0137] In one embodiment of the present invention, the catalyst is
prepared by mixing and heating one or more phosphorus containing
compounds described by one of the formulae (IX) to (XXX) or any of
the hydrated forms, and one or more sulfate salts described by one
of the formulae (XLIX) to (LII) or any of the hydrated forms.
[0138] In one embodiment of the present invention, the catalyst is
prepared by mixing and heating one or more phosphorus containing
compounds described by one of the formulae (IX) to (XXX) or any of
the hydrated forms, and one or more hydroxides described by one of
the formulae (LIII) to (LV) or any of the hydrated forms.
[0139] In one embodiment of the present invention, the catalyst is
prepared by mixing and heating one or more phosphorus containing
compounds of formulae (IX) to (XXX), and two or more non-phosphorus
containing compounds of formulae (XXXI) to (LV) or their hydrated
forms.
[0140] In one embodiment of the present invention, the method of
preparing the catalyst includes contacting: (a) a gaseous mixture
comprising water, with (b) a mixture of compounds containing at
least one condensed phosphate anion selected from the group
consisting of formulae (VI) to (VIII),
[P.sub.nO.sub.3n+1].sup.(n+2)- (VI)
[P.sub.nO.sub.3n].sup.n- (VII)
[P.sub.(2m+n)O.sub.(5m+3n)].sup.n- (VIII)
wherein n is at least 2; wherein m is at least 1; wherein, said
mixture of compounds is essentially neutrally charged; and further,
wherein the molar ratio of phosphorus to the monovalent and
polyvalent cations in the catalyst is between about 0.7 and about
1.7. In another embodiment, the molar ratio of phosphorus to the
monovalent and polyvalent cations is about 1.
[0141] In yet another embodiment, the catalyst is prepared by the
steps including contacting: (a) a gaseous mixture comprising water,
with (b) a mixture of compounds containing a condensed phosphate
salt selected from the group consisting of
Ba.sub.2-x-sK.sub.2xH.sub.2sP.sub.2O.sub.7,
Ca.sub.2-x-sK.sub.2xH.sub.2sP.sub.2O.sub.7,
Mn.sub.1-x-sK.sub.1+3xH.sub.3sP.sub.2O.sub.7,
Mn.sub.1-x-sK.sub.2+2xH.sub.2sP.sub.2O.sub.7, and mixtures thereof;
and (KPO.sub.3).sub.n; wherein x and s are greater or equal to 0
and less than about 0.5 and n is at least 2.
[0142] In one embodiment, the molar ratio of phosphorus to the
cations (i.e., M.sup.I+M.sup.II+M.sup.III+ . . . ) is between about
0.7 and about 1.7; in another embodiment, the molar ratio of
phosphorus to the cations (i.e., M.sup.I+M.sup.II+M.sup.III+ . . .
) is between about 0.8 and about 1.3, and in yet another
embodiment, the molar ratio of phosphorus to the cations (i.e.,
M.sup.I+M.sup.II+M.sup.III+ . . . ) is about 1. For example, in an
embodiment when the catalyst includes potassium (IC) and barium
(Ba.sup.2+), the molar ratio between phosphorus and the metals
(K+Ba) is between about 0.7 and about 1.7; and in another
embodiment, the molar ratio between phosphorus and the metals
(K+Ba) is about 1.
[0143] In one embodiment, the catalyst can include an inert support
that is constructed of a material comprising silicates, aluminates,
carbons, metal oxides, and mixtures thereof. Alternatively, the
carrier is inert relative to the reaction mixture expected to
contact the catalyst. In another embodiment, the method of
preparing the catalyst can further include mixing an inert support
with the catalyst before, during, or after the mixing and heating
of the phosphorus containing compounds, wherein the inert support
includes silicates, aluminates, carbons, metal oxides, and mixtures
thereof. In yet another embodiment, the method of preparing the
catalyst can further include mixing an inert support with the
catalyst before, during, or after the mixing and heating of the
phosphorus containing compounds and the non-phosphorus containing
compounds, wherein the inert support includes silicates,
aluminates, carbons, metal oxides, and mixtures thereof.
[0144] Mixing of the phosphorus containing compounds or the
phosphorus containing and non-phosphorus containing compounds of
the catalyst can be performed by any method known to those skilled
in the art, such as, by way of example and not limitation: solid
mixing and co-precipitation. In the solid mixing method, the
various components are physically mixed together with optional
grinding using any method known to those skilled in the art, such
as, by way of example and not limitation, shear, extensional,
kneading, extrusion, and others. In the co-precipitation method, an
aqueous solution or suspension of the various components, including
one or more of the phosphate compounds, is prepared, followed by
optional filtration and heating to remove solvents and volatile
materials (e.g., water, nitric acid, carbon dioxide, ammonia, or
acetic acid). The heating is typically done using any method known
to those skilled in the art, such as, by way of example and not
limitation, convection, conduction, radiation, microwave heating,
and others.
[0145] In one embodiment of the invention, the catalyst is
calcined. Calcination is a process that allows chemical reaction
and/or thermal decomposition and/or phase transition and/or removal
of volatile materials. The calcination process is carried out with
any equipment known to those skilled in the art, such as, by way of
example and not limitation, furnaces or reactors of various
designs, including shaft furnaces, rotary kilns, hearth furnaces,
and fluidized bed reactors. The calcination temperature is, in one
embodiment, about 200.degree. C. to about 1200.degree. C.; in
another embodiment, the calcination temperature is about
250.degree. C. to about 900.degree. C.; and in yet another
embodiment, the calcination temperature is about 300.degree. C. to
600.degree. C. The calcination time is, in one embodiment, about
one hour to about seventy-two hours.
[0146] While many methods and machines are known to those skilled
in the art for fractionating particles into discreet sizes and
determining particle size distribution, sieving is one of the
easiest, least expensive, and common ways. An alternative way to
determine the size distribution of particles is with light
scattering. Following calcination, the catalyst is, in one
embodiment, ground and sieved to provide a more uniform product.
The particle size distribution of the catalyst particles includes a
particle span that, in one embodiment, is less than about 3; in
another embodiment, the particle size distribution of the catalyst
particles includes a particle span that is less than about 2; and
in yet another embodiment, the particle size distribution of the
catalyst particles includes a particle span that is less than about
1.5. In another embodiment of the invention, the catalyst is sieved
to a median particle size of about 50 .mu.m to about 500 .mu.m. In
another embodiment of the invention, the catalyst is sieved to a
median particle size of about 100 .mu.m to about 200 .mu.m.
[0147] In one embodiment of the present invention, the catalyst is
prepared by the steps including combining BaHPO.sub.4 and
KH.sub.2PO.sub.4 in a molar ratio between about 3:2 and about 2:3
to form a solid mixture, and grinding said solid mixture to produce
the catalyst.
[0148] In another embodiment of the present invention, the catalyst
is prepared by the steps including: (a) combining BaHPO.sub.4 and
KH.sub.2PO.sub.4 in a molar ratio between about 3:2 and about 2:3
to form a solid mixture; (b) grinding said solid mixture to produce
a mixed powder; (c) calcining said mixed powder at about
550.degree. C. to produce a condensed phosphate mixture; and (d)
contacting said condensed phosphate mixture with a gaseous mixture
comprising water and lactic acid at a temperature of about
350.degree. C. and a total pressure of about 25 bar to produce said
catalyst, and wherein the partial pressure of water in said gaseous
mixture is about 12.5 bar.
[0149] In another embodiment, the catalyst is prepared by the
following steps, which comprise: (a) combining a phosphorus
containing compound, a nitrate salt, phosphoric acid, and water to
form a wet mixture, wherein the molar ratio between phosphorus and
the cations in both said phosphorus containing compound and said
nitrate salt is about 1, (b) calcining said wet mixture stepwise at
about 50.degree. C., about 80.degree. C., about 120.degree. C., and
about 450.degree. C. to about 550.degree. C. to produce a dried
solid, and (c) grinding and sieving said dried solid to about 100
.mu.m to about 200 .mu.m, to produce said catalyst.
[0150] In another embodiment, the catalyst is prepared by the
following steps, which comprise: (a) combining MnPO.sub.4qH.sub.2O,
KNO.sub.3, and H.sub.3PO.sub.4, in a molar ratio of about 0.3:1:1,
on an anhydrous basis, and water to give a wet mixture, (b)
calcining said wet mixture stepwise at about 50.degree. C., about
80.degree. C., about 120.degree. C., and about 450.degree. C. to
about 550.degree. C. to give a dried solid, and (c) grinding and
sieving said dried solid to about 100 .mu.m to about 200 .mu.m, to
produce said catalyst.
[0151] In another embodiment, the catalyst is prepared by the
following steps, which comprise: (a) combining
Ca.sub.2P.sub.2O.sub.7, KNO.sub.3, and H.sub.3PO.sub.4, in a molar
ratio of about 1.6:1:1, and water to give a wet mixture, (b)
calcining said wet mixture stepwise at about 50.degree. C., about
80.degree. C., about 120.degree. C., and about 450.degree. C. to
about 550.degree. C. to give a dried solid, and (c) grinding and
sieving said dried solid to about 100 .mu.m to about 200 .mu.m, to
produce said catalyst.
[0152] In another embodiment, the catalyst is prepared by the
following steps, which comprise: (a) combining a phosphorus
containing compound, a nitrate salt, phosphoric acid, and water to
give a wet mixture, wherein the molar ratio between phosphorus and
the cations in both the phosphorus containing compound and nitrate
salt is about 1, (b) heating said wet mixture to about 80.degree.
C. with stirring until near dryness to form a wet solid, (c)
calcining said wet solid stepwise at about 50.degree. C., about
80.degree. C., about 120.degree. C., and about 450.degree. C. to
about 550.degree. C. to give a dried solid, and (d) grinding and
sieving said dried solid to about 100 .mu.m to about 200 .mu.m, to
produce said catalyst.
[0153] In another embodiment, the catalyst is prepared by the
following steps, which comprise: (a) combining Ba(NO.sub.3).sub.2,
K.sub.2HPO.sub.4, and H.sub.3PO.sub.4, in a molar ratio of about
3:1:4, and water to give a wet mixture, (b) heating said wet
mixture to about 80.degree. C. with stirring until near dryness to
form a wet solid, (c) calcining said wet solid stepwise at about
50.degree. C., about 80.degree. C., about 120.degree. C., and about
450.degree. C. to about 550.degree. C. to give a dried solid, and
(d) grinding and sieving said dried solid to about 100 .mu.m to
about 200 .mu.m, to produce said catalyst.
[0154] In yet another embodiment of the present invention, the
catalyst is prepared by the steps including: (a) combining
K.sub.2HPO.sub.4, Ba(NO.sub.3).sub.2, H.sub.3PO.sub.4, and water to
form a wet mixture, wherein the molar ratio of Ba(NO.sub.3).sub.2,
K.sub.2HPO.sub.4, and H.sub.3PO.sub.4 is about 3:1:4; (b) heating
said wet mixture to about 80.degree. C. with stirring until near
dryness to form a wet solid; (c) calcining said wet solid stepwise
at about 50.degree. C., about 80.degree. C., about 120.degree. C.,
and about 450.degree. C. to about 550.degree. C. to produce a dried
solid; and (d) contacting said dried solid with a gaseous mixture
comprising water and lactic acid at a temperature of about
350.degree. C. and a total pressure of about 25 bar to produce said
catalyst, and wherein the partial pressure of water in said gaseous
mixture is about 12.5 bar.
[0155] In another embodiment, the catalyst is prepared by the
following steps, which comprise: (a) combining
Mn(NO.sub.3).sub.24H.sub.2O, K.sub.2HPO.sub.4, and H.sub.3PO.sub.4,
in a molar ratio of about 1:1.5:2, and water to give a wet mixture,
(b) heating said wet mixture to about 80.degree. C. with stirring
until near dryness to form a wet solid, (c) calcining said wet
solid stepwise at about 50.degree. C., about 80.degree. C., about
120.degree. C., and about 450.degree. C. to about 550.degree. C. to
give a dried solid, and (d) grinding and sieving said dried solid
to about 100 .mu.m to about 200 .mu.m, to produce said
catalyst.
[0156] In another embodiment, the catalyst is prepared by the
following steps, which comprise: (a) combining
Ca.sub.2P.sub.2O.sub.7 and KH.sub.2PO.sub.4 in a molar ratio of
about 3:1 to give a solid mixture, and (b) calcining said solid
mixture stepwise at about 50.degree. C., about 80.degree. C., about
120.degree. C., and about 450.degree. C. to about 550.degree. C.,
to produce said catalyst.
[0157] Following calcination and optional grinding and sieving, the
catalyst can be utilized to catalyze several chemical reactions.
Non-limiting examples of reactions are: dehydration of
hydroxypropionic acid to acrylic acid (as described in further
detail below), dehydration of glycerin to acrolein, dehydration of
aliphatic alcohols to alkenes or olefins, dehydrogenation of
aliphatic alcohols to ethers, other dehydrogenations, hydrolyses,
alkylations, dealkylations, oxidations, disproportionations, es
terific ations , cyclizations, isomerizations, condensations,
aromatizations, polymerizations, and other reactions that may be
apparent to those having ordinary skill in the art.
V EXAMPLES
[0158] The following examples are provided to illustrate the
invention, but are not intended to limit the scope thereof.
Example 1
[0159] Solid dibasic potassium phosphate, K.sub.2HPO.sub.4 (36.40
g, 209 mmol, .gtoreq.98%; Sigma-Aldrich Co., St. Louis, Mo.;
catalog # P3786) was mixed quickly with an aqueous solution of
barium nitrate, Ba(NO.sub.3).sub.2 (2050 mL of a 0.08 g/mL stock
solution, 627 mmol, 99.999%; Sigma-Aldrich
[0160] Co., St. Louis, Mo.; catalog # 202754) at room temperature.
Phosphoric acid, H.sub.3PO.sub.4 (58.7 mL of an 85 wt %,
density=1.684 g/mL, 857 mmol; Acros Organics, Geel, Belgium;
catalog #295700010), was added to the slurry, providing a solution
containing potassium (K.sup.+, M.sup.I) and barium (Ba.sup.2+,
M.sup.II) cations. The final pH of the suspension was about 1.6.
The acid-containing suspension was then dried slowly in a glass
beaker at 80.degree. C. using a heating plate while magnetically
stirring the suspension until the liquid was evaporated and the
material was almost completely dried. Heating was continued in a
oven with air circulation (G1530A, HP6890 GC; Agilent Corp., Santa
Clara, Calif.) at 50.degree. C. for 5.3 h, then at 80.degree. C.
for 10 h (0.5.degree. C./min ramp), following by cooling down at
25.degree. C. The material was calcined at 120.degree. C. for 2
hours (0.5.degree. C./min ramp) followed by 450.degree. C. for 4
hours (2.degree. C./min ramp) using the same oven. After
calcination, the material was left inside the oven until it cooled
down by itself at a temperature below 25.degree. C. before it was
taken out of the oven. Finally, the catalyst was ground and sieved
to about 100 .mu.m to about 200 .mu.m.
Example 2
[0161] 113.6 g of an 88 wt % L-lactic acid solution (Purac Corp.,
Lincolnshire, Ill.) was diluted with 386.4 g of distilled water to
provide a solution with an expected lactic acid concentration of 20
wt %. This solution was heated to 95.degree. C.-100.degree. C. and
for 12-30 hours. Then, the solution was cooled to room temperature,
and its lactic acid and lactic acid oligomers concentrations were
measured by HPLC (Agilent 1100 system; Santa Clara, Calif.)
equipped with a DAD detector and a Waters Atlantis T3 column
(Catalog # 186003748; Milford, Mass.) using methods generally known
by those having ordinary skill in the art. The solution was
essentially free of oligomers.
Example 3
[0162] 454 g of an 88 wt % L-lactic acid solution (Purac Corp.,
Lincolnshire, Ill.) was diluted with 1,300 g of water. The diluted
solution was heated to 95.degree. C. and held at that temperature
with stirring for about 4 to 12 hours. Then, the solution was
cooled to room temperature, and its lactic acid and lactic acid
oligomers concentrations were measured by HPLC (Agilent 1100
system; Santa Clara, Calif.) equipped with a DAD detector and a
Waters Atlantis T3 column (Catalog # 186003748; Milford, Mass.)
using methods generally known by those having ordinary skill in the
art. The solution was essentially free of oligomers. Finally, the
solution was further diluted with water to yield a 20 wt % L-lactic
acid aqueous solution and essentially free of oligomers.
Example 4
[0163] A 13'' (33 cm) long stainless steel glass lined tube (SGE
Analytical Science Pty Ltd., Ringwood, Australia) with a 4.0 mm
internal diameter (ID) was packed with 3'' (7.6 cm) bed length
glass wool and 5'' (12.7 cm) the catalyst from Example 1 (1.6 mL
bed volume) to give an 2.55 mL total packed bed (8'' or 20.3 cm)
and 1.6 mL (5'' or 12.7 cm) of free space at the top of the
reactor. The tube was placed inside an aluminum block and placed in
a clam shell furnace series 3210 (Applied Test Systems, Butler,
Pa.), such that the top of the packed bed was aligned with the top
of the aluminum block. The reactor was setup in a down flow
arrangement and was equipped with a Knauer Smartline 100 feed pump
(Berlin, Germany), a Brooks 0254 gas flow controller (Hatfield,
Pa.), a Brooks back pressure regulator, and a catch tank. The clam
shell furnace was heated, such that the reactor wall temperature
was kept constant at about 350.degree. C. during the course of the
reaction. The reactor was supplied with separate liquid and gas
feeds that were mixed together before reaching the catalyst bed.
The gas feed was composed of molecular nitrogen at about 360 psig
and at a flow of 45 mL/min The liquid feed was a 20 wt % aqueous
solution of L-lactic acid, prepared as in Example 2, and fed at
0.045 mL/min (LHSV of 1.7 h.sup.-1), giving a residence time of
about 1 s (GHSV of 3,600 h.sup.-1) at STP conditions. After flowing
through the reactor, the gaseous stream was cooled and the liquid
was collected in the catch tank over 6 h and 42 min (402 min in
total) for analysis by off-line HPLC (Agilent 1100 system; Santa
Clara, Calif.) equipped with a DAD detector and a Waters Atlantis
T3 column (Catalog # 186003748; Milford, Mass.) using methods
generally known by those having ordinary skill in the art. The
gaseous stream was analyzed on-line by GC (Agilent 7890 system;
Santa Clara, Calif.) equipped with a FID detector and Varian
CP-Para Bond Q column (Catalog # CP7351; Santa Clara, Calif.). The
acrylic acid aqueous solution had 14.8 wt % acrylic acid and 1.5 wt
% lactic acid. The acrylic acid yield was 80%, its selectivity was
85%, and the lactic acid conversion was 94%.
Example 5
[0164] The reactor consisted of an electric clam shell furnace
(Applied Test systems, Butler, Pa.) with an 8'' (20.3 cm) heated
zone with one temperature controller connected in series to another
electric clam shell furnace (Applied Test Systems, Butler, Pa.)
with a 16'' (40.6 cm) heated zone containing two temperature
controllers and a reactor tube. The reactor tube consisted of a
13'' (33 cm) borosilicate glass-lined tube (SGE Analytical Science
Pty Ltd., Ringwood, Australia)) and a 23'' (58.4 cm) borosilicate
glass lined tube connected in series using a Swagelok.TM. tee
fitting equipped with an internal thermocouple and having an inside
diameter of 9.5 mm The head of the column was fitted with a 1/8''
(3.2 mm) stainless steel nitrogen feed line and a 1/16'' (1.6 mm)
fused silica lined stainless steel liquid feed supply line
connected to a HPLC pump (Smartline 100, Knauer, Berlin, Germany)
that was connected to a lactic acid feed tank. The bottom of the
reactor was connected to a Teflon-lined catch tank using 1/8'' (3.2
mm) fused silica lined stainless steel tubing and Swagelok.TM.
fittings. The reactor column was packed with a plug of glass wool,
13 g of fused quartz, 16'' (40.7 cm) with catalyst of Example 1 (47
g and 28.8 mL packed bed volume) and topped with 25 g of fused
quartz. The reactor tube was placed in an aluminum block and placed
into the reactor from above in a downward flow. The reactor was
preheated to 375.degree. C. overnight under 0.25 L/min nitrogen.
The nitrogen feed was increased to 0.85 L/min during the
experiment. The liquid feed was a 20 wt % aqueous solution of
L-lactic acid, prepared as in Example 3, and fed at 0.845 mL/min
(LHSV of 1.8 11.sup.-1; 50.7 g/h), giving a residence time of about
1 s (GHSV of 3,600 h.sup.-1) at STP conditions. The clam shell
heaters were adjusted to give an internal temperature about
350.degree. C. After flowing through the reactor, the gaseous
stream was cooled and the liquid was collected in the catch tank
for analysis by off-line HPLC using an Agilent 1100 system (Santa
Clara, Calif.) equipped with a DAD detector and a Waters Atlantis
T3 column (Catalog # 186003748; Milford, Mass.) using methods
generally known by those having ordinary skill in the art. The
gaseous stream was analyzed on-line by GC using an Agilent 7890
system (Santa Clara, CA) equipped with a FID detector and
Varian
[0165] CP-Para Bond Q column (Catalog # CP7351; Santa Clara,
Calif.). The crude reaction mixture was cooled and collected over
159 h to give 748 g acrylic acid as a crude mixture in 54% yield,
75% acrylic acid selectivity, and 69% conversion of lactic acid.
The acrylic acid yield, corrected for the losses during the
evaporating step, was 61% and its selectivity was 89%. The acrylic
acid aqueous concentration was 8.4 wt %, and that of lactic acid
was 6.3 wt %.
Example 6
[0166] Experiments without catalyst present further demonstrated
the effect of feed stabilization in a quartz reactor. All runs were
performed using a 0.2 mL reactor. Empty reactors were compared to
those packed with fused silica (SiO.sub.2) (Sigma-Aldrich Co., St.
Louis, Mo.) and Zirblast (Saint Gobain Zirpro, Le Pontet Cedex,
France) in both stainless steel (SS) and quartz reactors. The
results are reported in Table 1 below.
[0167] The 0.2 mL reactor system comprised temperature and mass
flow controllers and was supplied with separate liquid and gas
feeds that were mixed together before reaching the catalyst bed.
The gas feed was composed of molecular nitrogen (N.sub.2) and
helium (He), which was added as an internal standard for the gas
chromatograph (GC) analysis. The liquid feed was a 20 wt % aqueous
solution of L-lactic acid, prepared as in 2, and fed to the top of
the reactor while controlling the pump pressure to about 360 psig
to overcome any pressure drop from the catalyst bed. Quartz or
stainless steel reactors with an aspect ratio (i.e.,
length/diameter) of 75 were used.
[0168] Various catalyst beds and gas feed flows were used resulting
in a range of space velocities (reported herein). The reactor
effluent was also connected to another nitrogen dilution line,
which diluted the effluent by a factor of two. The helium internal
standard normalized any variation in this dilution for analytical
purposes. The condensed products were collected by a liquid
sampling system cooled to between 6.5.degree. C. to 10.degree. C.
while the gaseous products accumulated on the overhead space of a
collection vial. The overhead gaseous products were analyzed using
sampling valves and online gas chromatography (GC).
[0169] The feed was equilibrated for 1 hour, after which time the
liquid sample was collected for 2.7 hours and analyzed at the end
of the experiment by offline HPLC. During this time, the gas
products were analyzed online twice by GC and reported as an
average. Liquid products were analyzed by high performance liquid
chromatography (HPLC) using an Agilent 1200 Series instrument
(Agilent Technologies, Santa Clara, Calif.), a Supelcogel-H column
(4.6.times.250 mm; Supelco, St. Louis, Mo.), and a diode-array and
a refraction index (RI) detectors. Analytes were eluted
isocratically, using 0.005 M H.sub.2SO.sub.4 (aq.) as the elution
buffer, over a period of 30 min and at a flow of 0.2 mL/min The
column and RI detector temperatures were set at 30.degree. C.
Gaseous products were analyzed by an Interscience Compact gas
chromatography (GC) system (Interscience BV, Breda, Netherlands)
using three detectors (one flame ionization detector--FID --and two
thermal conductivity--TCD-- detectors "A" and "B," referred to
hereinafter as "TCD-A" and "TCD-B," respectively). The gaseous
products were reported as an average given by two sequential GC
chromatograms.
[0170] The TCD-A column was an Rt-Q Bond (Restek Corp., Bellefonte,
Pa.), having 26 m in length and an I.D. of 0.32 mm with a film
thickness of 10 .mu.m and using a pre-column of 2 m. The pressure
was set to 150 kPa, with a split flow of 10 mL/min The column oven
temperature was set to 100.degree. C. with a vale oven temperature
of 50.degree. C. The flow was set to 5 0 mL/min, with a carrier gas
of helium. The TCD-B column was a Mol sieve MSSA (Restek Corp.,
Bellefonte, Pa.), having a length of 21 m and a film thickness of
10 .mu.m and using a pre-column of 2 m. The pressure was set to 200
kPa, with a split flow of 10 mL/min The column oven temperature was
set to 70.degree. C. with a vale oven temperature of 50.degree. C.
The flow was set to 2 0 mL/min, with a carrier gas of argon. The
FID column was a RTx-624 (Restek, Bellefonte, Pa.), having a length
of 28 m and an inner diameter of 0.25 mm with a film thickness of
14 mm and using a pre-column of 2 m. The pressure was set to 100
kPa, with a split flow to 20 mL/min The column oven temperature was
set to 45.degree. C. with a vale oven temperature of 50.degree.
C.
VI Results
TABLE-US-00001 [0171] TABLE 1 LA Con- AA AA PA Inert Reactor GHSV,
version, Selectivity, Yield, Yield, Packing Material (h.sup.-1) (%)
(%) (%) (%) Empty Quartz 3,453 18 0 0.2 0.2 Empty SS 3,453 71.7 0
0.2 13.7 Fused Quartz 3,489 25 0.05 1.4 2.9 SiO.sub.2 Fused SS
3,489 68.6 0 0 13.4 SiO.sub.2 Zirblast Quartz 3,489 21.8 0 0 0.2
Zirblast SS 3,489 70 0 0 13
[0172] The results reported in Table 1 indicate that at high space
velocities, very little byproducts were observed when quartz
reactors were used, with or without inert packing. Thus, it was
determined that the use of quartz reactors minimized two important
side reactions: lactic acid oligomerization and reduction to
propionic acid. This is important to evaluating the true activity
of catalysts.
[0173] The foregoing description is given for clearness of
understanding only, and no unnecessary limitations should be
understood therefrom, as modifications within the scope of the
invention may be apparent to those having ordinary skill in the
art.
[0174] The dimensions and values disclosed herein are not to be
understood as being strictly limited to the exact numerical values
recited. Instead, unless otherwise specified, each such dimension
is intended to mean both the recited value and a functionally
equivalent range surrounding that value. For example, a dimension
disclosed as "40 mm" is intended to mean "about 40 mm."
[0175] Every document cited herein, including any cross referenced
or related patent or application, is hereby incorporated herein by
reference in its entirety unless expressly excluded or otherwise
limited. The citation of any document is not an admission that it
is prior art with respect to any invention disclosed or claimed
herein or that it alone, or in any combination with any other
reference or references, teaches, suggests or discloses any such
invention. Further, to the extent that any meaning or definition of
a term in this document conflicts with any meaning or definition of
the same term in a document incorporated by reference, the meaning
or definition assigned to that term in this document shall
govern.
[0176] While particular embodiments of the present invention have
been illustrated and described, it would be obvious to those
skilled in the art that various other changes and modifications can
be made without departing from the spirit and scope of the
invention. It is therefore intended to cover in the appended claims
all such changes and modifications that are within the scope of
this invention.
* * * * *