U.S. patent application number 14/432005 was filed with the patent office on 2016-02-04 for method for preparing catalyst for glycerin dehydration, and method for preparing acrolein.
This patent application is currently assigned to LG CHEM, LTD.. The applicant listed for this patent is LG CHEM, LTD.. Invention is credited to Joo Young CHEON, Jun Seon CHOI, Wang Rae JOE, Ji Yeon KIM.
Application Number | 20160030929 14/432005 |
Document ID | / |
Family ID | 53057560 |
Filed Date | 2016-02-04 |
United States Patent
Application |
20160030929 |
Kind Code |
A1 |
JOE; Wang Rae ; et
al. |
February 4, 2016 |
METHOD FOR PREPARING CATALYST FOR GLYCERIN DEHYDRATION, AND METHOD
FOR PREPARING ACROLEIN
Abstract
The present invention relates to a method for preparing a
catalyst for glycerin dehydration, a catalyst for glycerin
dehydration prepared thereby, and a method for preparing acrolein.
More particularly, the catalyst for glycerin dehydration prepared
by the preparation method is able to minimize by-product formation
to improve acrolein selectivity and to maintain high catalytic
activity during the reaction.
Inventors: |
JOE; Wang Rae; (Daejeon,
KR) ; CHOI; Jun Seon; (Daejeon, KR) ; KIM; Ji
Yeon; (Daejeon, KR) ; CHEON; Joo Young;
(Daejeon, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LG CHEM, LTD. |
Seoul |
|
KR |
|
|
Assignee: |
LG CHEM, LTD.
Seoul
KR
|
Family ID: |
53057560 |
Appl. No.: |
14/432005 |
Filed: |
June 20, 2014 |
PCT Filed: |
June 20, 2014 |
PCT NO: |
PCT/KR2014/005486 |
371 Date: |
March 27, 2015 |
Current U.S.
Class: |
568/486 ;
423/263; 502/263 |
Current CPC
Class: |
B01J 37/036 20130101;
B01J 37/08 20130101; C07C 45/512 20130101; B01J 27/182 20130101;
B01J 23/10 20130101; C07C 45/52 20130101; B01J 37/28 20130101; C01B
25/37 20130101; C07C 45/52 20130101; C07C 47/22 20130101 |
International
Class: |
B01J 27/182 20060101
B01J027/182; C07C 45/51 20060101 C07C045/51; B01J 37/08 20060101
B01J037/08; C01B 25/37 20060101 C01B025/37; B01J 37/28 20060101
B01J037/28 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 13, 2013 |
KR |
1020130137717 |
Claims
1. A method for preparing a catalyst for glycerin dehydration,
comprising the steps of: reacting a cerium precursor with a solid
acid; and reacting a reaction product of the cerium precursor and
the solid acid with a phosphorus precursor.
2. The method of claim 1, wherein the step of reacting the cerium
precursor and the solid acid includes a sol-gel reaction.
3. The method of claim 2, wherein the sol-gel reaction includes a
step of heating at a temperature of 20 to 20.degree. C.
4. The method of claim 1, wherein a mixing molar ratio of the
cerium precursor and the phosphorus precursor is 1:1 to 1:10.
5. The method of claim 1, wherein the cerium precursor includes one
or more selected from the group consisting of cerium nitrate,
cerium carbonate, cerium chloride, cerium sulfate, and cerium
acetate.
6. The method of claim 1, wherein the phosphorus precursor includes
one or more selected from the group consisting of H.sub.3PO.sub.4,
(NH.sub.3).sub.2HPO.sub.4, and (C.sub.2H.sub.5).sub.3PO.sub.4.
7. The method of claim 1, wherein the solid acid includes one or
more selected from the group consisting of citric acid, succinic
acid, malic acid, and tartaric acid.
8. The method of claim 1, wherein the step of reacting the cerium
precursor with the solid acid is conducted by further including a
solvent selected from the group consisting of water and
alcohols.
9. The method of claim 1, further comprising the step of
calcinating a product resulting from the reaction of the reaction
product of the cerium precursor and the solid acid with the
phosphorus precursor.
10. The method of claim 9, wherein the calcination step is
conducted in a temperature range from 100 to 1200.degree. C.
11. The method of claim 9, wherein the calcination step is
conducted for 10 minutes to 10 hours.
12. The method of claim 1, further comprising the step of
supporting a product, which is obtained from the reaction of the
reaction product of the cerium precursor and the solid acid with
the phosphorus precursor, on a carrier.
13. The method of claim 12, further comprising the step of
supporting the reaction product of the cerium precursor and the
solid acid on a carrier, before the step of supporting the product,
which is obtained from the reaction of the reaction product of the
cerium precursor and the solid acid with the phosphorus precursor,
on a carrier.
14. The method of claim 12, wherein the carrier is selected from
the group consisting of silica, alumina, silica-alumina, titania,
zeolite, activated carbon, clay, zirconia, magnesia, magnesium
aluminate, calcium aluminate, silicon carbide, and zirconium
phosphorus oxide, and mixtures thereof.
15. A method for preparing acrolein, comprising the step of
reacting glycerin in the presence of the catalyst for glycerin
dehydration of claim 1.
16. The method of claim 15, wherein the dehydration is conducted at
a temperature of 200 to 400.degree. C.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method for preparing a
catalyst for dehydration and a method for preparing acrolein, and
particularly, to a method for preparing a catalyst for glycerin
dehydration, which is able to minimize by-product formation to
improve acrolein selectivity and to maintain high catalytic
activity during the reaction, and a method for preparing
acrolein.
BACKGROUND OF ART
[0002] Acrolein is a simple unsaturated aldehyde compound including
an incomplete reactive group and having high reactivity, and the
main uses thereof are as an intermediate in the synthesis of
numerous compounds. In particular, acrolein has been widely used as
an intermediate in the synthesis of acrylic acid and its esters,
superabsorbent polymers, animal feed supplements, food supplements,
etc.
[0003] Conventionally, acrolein has been prepared by a selective
gas-phase oxidation reaction with atmospheric oxygen using a
starting material, propylene, which is obtained from the processing
of petroleum. However, as reduction in fossil fuels and
environmental problems such as the greenhouse effect gradually
emerge, many studies have been conducted on a synthetic method of
producing acrolein using renewable non-fossil fuel based raw
materials.
[0004] Accordingly, a natural product, glycerin, obtained as a
by-product of biodiesel production, has gained much interest as a
raw material for acrolein synthesis. In particular, as the
production of biodiesel increases, the glycerin market is
expanding, and due to reduction of glycerin price, industrial
applications thereof have been studied. For example, there is known
a method of obtaining acrolein by dehydration of glycerin in the
presence of a catalyst, and the method is known to be performed by
using an acidic catalyst such as zeolite, phosphorus oxide, and
tungstophosphoric acid (H.sub.3PW.sub.12O.sub.4).
[0005] However, since the catalysts which were previously used to
prepare acrolein from glycerin produce by-products such as hydroxy
acetone, hydroxy propanone, propane aldehyde, acetaldehyde,
acetone, and polycondensation products of glycerin, there is a
limitation in the use of the catalysts for the production of
acrolein with high purity. Further, there is a problem that when
the catalyst is supported on a carrier, the catalytic activity is
rapidly reduced.
[0006] Accordingly, there is a demand to develop a method for
preparing a catalyst for glycerin dehydration, which is able to
minimize by-product formation to improve selectivity and purity of
acrolein and conversion ratio and reaction yield of glycerin, and
to maintain high catalytic activity even though supported on a
carrier.
DETAILED DESCRIPTION OF THE INVENTION
Technical Problem
[0007] The present invention provides a method for preparing a
catalyst for glycerin dehydration, which is able to minimize
by-product formation to improve acrolein selectivity and to
maintain high catalytic activity.
[0008] Further, the present invention provides a method for
preparing acrolein using the catalyst for glycerin dehydration.
Technical Solution
[0009] The present invention provides a method for preparing a
catalyst for glycerin dehydration, including the steps of reacting
a cerium precursor with a solid acid; and reacting a reaction
product of the cerium precursor and the solid acid with a
phosphorus precursor.
[0010] Further, the present invention provides a method for
preparing acrolein, including the step of reacting glycerin in the
presence of the catalyst for glycerin dehydration.
[0011] Hereinafter, a method for preparing a catalyst for
dehydration and a method for preparing acrolein according to
specific embodiments of the present invention will be described in
more detail.
[0012] According to one embodiment of the present invention,
provided is a method for preparing a catalyst for glycerin
dehydration, including the steps of reacting a cerium precursor
with a solid acid; and reacting a reaction product of the cerium
precursor and the solid acid with a phosphorus precursor.
[0013] The present inventors recognized that the previous catalysts
used for preparation of acrolein from glycerin produce by-products
such as polycondensation products, and thus there is a limitation
in the use of the catalysts for the production of acrolein with
high purity, and there is also a problem that when the catalyst is
supported on a carrier, the catalytic activity is rapidly reduced.
Accordingly, the present inventors studied to solve these problems.
Consequently, they performed experiments to demonstrate that a
catalyst for glycerin dehydration prepared by reacting a cerium
precursor with a solid acid and then reacting the product with a
phosphorus precursor is able to minimize by-product formation and
also prepares acrolein with high yield and high conversion ratio,
thereby completing the present invention.
[0014] In particular, the method for preparing the catalyst for
glycerin dehydration is able to prepare a catalyst which includes a
solid acid to be used as a dispersing agent, thereby uniformly
dispersing cerium ions serving as active sites therein.
Accordingly, the catalyst for glycerin dehydration which is
prepared by the above preparation method shows high activity. The
catalyst which is prepared by the method for preparing the catalyst
for glycerin dehydration may be, for example, in the form of
CePO.sub.4 or CePO.sub.4/SiO.sub.2.
[0015] Further, the previous catalysts for glycerin dehydration
produce a large amount of by-products such as hydroxy acetone,
etc., but the catalyst prepared by the method for preparing the
catalyst for glycerin dehydration according to one embodiment
improves contact between a reactant and an active phase because the
active phase is uniformly dispersed in the catalyst, thereby
producing acrolein with a high yield.
[0016] In the method for preparing the catalyst for glycerin
dehydration according to one embodiment, the step of reacting the
cerium precursor and the solid acid may include a sol-gel reaction.
The sol-gel reaction may include the step of producing a sol in a
suspension state in which colloidal or inorganic unimolecular solid
molecules are dispersed, and the step of producing a gel when the
sol loses its fluidity resulting from formation of a continuous
solid network structure by maintaining the sol reaction to
polymerize the dispersed solid molecules.
[0017] Specifically, in the catalyst for glycerin dehydration
according to one embodiment, the cerium precursor and the solid
acid were reacted with each other at a temperature of 50 to
100.degree. C. and at atmospheric pressure for 2 to 10 hours to
prepare a sol, and the sol may be in the form in which the cerium
precursors are connected between solid acids.
[0018] The produced sol is transformed into a gel by heating and
drying the sol at a high temperature of 100 to 200.degree. C. so as
to prepare a gel-type product of a sol-gel reaction.
[0019] In the method for preparing the catalyst for glycerin
dehydration, a mixing molar ratio of the cerium precursor and the
phosphorus precursor may be 1:1 to 1:10, preferably 1:2 to 1:5. As
such, a larger amount of the phosphorus precursor than the cerium
precursor is mixed, thereby increasing the production ratio of
cerium phosphorus oxide having high activity and inhibiting
production of cerium oxide having low activity in a calcination
step, and therefore, activity of the catalyst for glycerin
dehydration thus prepared can be improved.
[0020] The cerium precursor or the phosphorus precursor
collectively refers to a substance for providing cerium or
phosphorus which is included in the catalyst for glycerin
dehydration, and for example, it may be in the form of an oxide or
salt containing cerium or phosphorus.
[0021] Specifically, the cerium precursor may include one or more
selected from the group consisting of cerium nitrate, cerium
carbonate, cerium chloride, cerium sulfate, cerium acetate, and
mixtures thereof, and use of cerium nitrate is preferred because
impurities such as NO.sub.x can be easily separated in the
preparation process of the catalyst.
[0022] Further, any phosphorus precursor can be used without
limitation as long as it is known to be used in the preparation of
the catalyst including phosphorus oxide, and for example,
H.sub.3PO.sub.4, (NH.sub.3).sub.2HPO.sub.4,
(C.sub.2H.sub.5).sub.3PO.sub.4, or a mixture thereof may be
used.
[0023] Citric acid, succinic acid, malic acid, tartaric acid, or a
mixture thereof may be used as the solid acid. These solid acids
function as a bridge that connects cerium and phosphorus components
in the precursor solutions with each other, and therefore, they
help prepare a catalyst having active sites which are more
uniformly dispersed. As confirmed in experimental examples below,
the catalyst for glycerin dehydration of one embodiment which is
prepared by using the solid acid is able to exhibit excellent
catalytic activity, high glycerin conversion ratio, and high
acrolein selectivity, compared to use of alkaline compounds such as
ammonia.
[0024] The step of reacting the cerium precursor with the solid
acid may be conducted by further including a solvent selected from
the group consisting of water, alcohols such as methanol or
ethanol, and mixtures thereof. In particular, when water is used as
the solvent, a sufficient time for gelation of the cerium precursor
is provided during evaporation of water, thereby obtaining a
catalyst in which the cerium components serving as active sites in
the catalyst to be prepared are dispersed uniformly in terms of
physicochemical properties.
[0025] The method for preparing the catalyst for glycerin
dehydration of one embodiment may further include the step of
calcinating a product resulting from the reaction of the reaction
product of the cerium precursor and the solid acid with the
phosphorus precursor.
[0026] The calcination step means a series of procedures to prepare
a curable material by heating the reaction product at a high
temperature, and it may be conducted in a temperature range from
100 to 1200.degree. C., preferably from 500 to 1000.degree. C. If
the temperature is lower than the above range, the structure and
crystallinity of the catalyst may change during reaction to
deteriorate the catalytic activity. If the temperature is higher
than the above range, the pore structure or the specific surface
area may be reduced to deteriorate the catalytic activity.
[0027] Further, the calcination step may be conducted for 10
minutes to 10 hours. If the calcination time is too short, the
catalyst may not be completely dried and calcined. If the
calcination time is too long, many side-reactions such as
carbonization of the catalyst may occur.
[0028] The drying step may be further included before the step of
calcinating the product resulting from the reaction of the reaction
product of the cerium precursor and the solid acid with the
phosphorus precursor. In the drying step, a drying method and a
drier which are known to be typically used may be used, and for
example, the drying step may be conducted using a heat source such
as a hot air generator, an oven, a heating plate, etc.
[0029] Meanwhile, the method for preparing the catalyst for
glycerin dehydration of one embodiment may further include the step
of supporting the product, which is obtained from the reaction of
the reaction product of the cerium precursor and the solid acid
with the phosphorus precursor, on a carrier. The step of supporting
the reaction product on the carrier may be performed by using a
method known to be used in the art without limitation, and this
step may be included in order to more easily store and transport
the catalyst for glycerin dehydration and to increase its surface
area for improvement of the reaction activity.
[0030] The step of supporting the reaction product of the cerium
precursor and the solid acid on a carrier may be included, before
the step of supporting the product, which is obtained from the
reaction of the reaction product of the cerium precursor and the
solid acid with the phosphorus precursor, on a carrier. That is,
the cerium precursor and the solid acid are reacted, the reaction
product thereof is supported on a carrier, and then the resultant
is reacted with the phosphorus precursor, followed by further
supporting on a carrier.
[0031] In particular, when the catalyst for glycerin dehydration
prepared according to the conventional preparation method is
supported on a carrier, its reaction activity is greatly reduced,
compared to the catalyst before being supported, so as to generate
a problem of performance reduction. In the above method for
preparing the catalyst for glycerin dehydration, however, the
cerium precursor and the solid acid are first reacted, and then
supported on a carrier, thereby maintaining high reaction activity
of the supported catalyst. The solid acid functions as a dispersing
agent to connect the cerium precursor and the carrier, leading to
uniform dispersion of the active phase of cerium in the carrier.
Also, the solid acid functions to improve the viscosity of the
resulting solution from the reaction with the cerium precursor,
leading to uniform dispersion of the active phase of cerium within
the pores of the carrier.
[0032] Any carrier may be used without particular limitation, as
long as it is known to be used in the typical catalyst. Specific
examples of the carrier may include silica, alumina,
silica-alumina, titania, zeolite, activated carbon, clay, zirconia,
magnesia, magnesium aluminate, calcium aluminate, silicon carbide,
zirconium phosphorus oxide, and a mixture thereof, and preferably,
silica having a pore size of 20 nm or more.
[0033] The carrier may have a specific surface area of 10 to 500
m.sup.2/g, and preferably, 50 to 200 m.sup.2/g. In particular, the
catalyst for glycerin dehydration prepared by supporting the
precursor on the carrier having a high specific surface area in the
above range has an appropriate pore size, and therefore, deposition
of coke can be reduced, and the sufficient catalytic activity can
be provided.
[0034] According to another embodiment of the present invention,
provided is a method for preparing acrolein including the step of
reacting glycerin in the presence of the catalyst for glycerin
dehydration which is prepared by the method for preparing the
catalyst for glycerin dehydration of one embodiment.
[0035] As described above, when the catalyst for glycerin
dehydration of one embodiment of the present invention is used,
dehydration of glycerin may be performed with high acrolein
selectivity, and in particular, by-product formation can be
minimized, compared to use of other catalysts previously known.
[0036] The use of the catalyst for glycerin dehydration may be
controlled depending on the amount and concentration of the
reactant glycerin, and for example, the catalyst may be fed at a
weight hourly space velocity of 10 to 300 mmol/hg.sub.cat,and
preferably, at a weight hourly space velocity of 10 to 100
mmol/hg.sub.cat.
[0037] Further, the step of reacting glycerin may be performed at a
temperature of 200 to 400.degree. C. Since the step of reacting
glycerin is an endothermic reaction, the reaction is preferably
performed within the temperature range in order to prepare acrolein
with high conversion ratio and selectivity.
Advantageous Effects
[0038] According to the present invention, provided are a method
for preparing a catalyst for glycerin dehydration, which is able to
minimize by-product formation to improve acrolein selectivity and
to maintain high catalytic activity during the reaction, and a
method for preparing acrolein.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0039] The present invention will be described in more detail with
reference to the following examples. However, the following
examples are for the illustrative purpose only, and the present
invention is not intended to be limited by these examples.
Examples and Comparative Examples
Preparation of Catalyst for Glycerin Dehydration
Example 1
[0040] A predetermined amount (7.723 g) of cerium nitrate
(Ce(NO.sub.3).sub.2.6H.sub.2O, YAKURI, 98.0%) was dissolved in 8 ml
of distilled water in a beaker so as to prepare a cerium precursor
solution. Further, 3.366 g of citric acid (YAKURI, 99.99%) at the
same molar equivalent as cerium nitrate was dissolved in 4 ml of
distilled water in another beaker so as to prepare a citric acid
solution. Then, the cerium nitrate solution and the citric acid
solution thus prepared were mixed with each other, and stirred for
30 minutes to completely mix the two solutions. While the mixed
solution was heated and stirred at a temperature of 70.degree. C.,
distilled water in the solution was evaporated to form a sol, and
the sol thus formed was continuously heated for about 3 hours to
form a gel. After gel formation, 2.211 g of phosphate
(H.sub.3PO.sub.4 DAEJUNG, 85%) solution at an equivalent weight of
1.1 was added dropwise. Then, the gel was allowed to swell by
continuous heating and stirring, and dried in an oven at
170.degree. C. for about 12 hours to completely remove NO gas.
Thereafter, the gel was calcined in a furnace under an air
atmosphere at 800.degree. C. for 4 hours to prepare a CePO.sub.4
catalyst.
Example 2
[0041] A predetermined amount (0.565 g) of cerium nitrate
(Ce(NO.sub.3).sub.2.6H.sub.2O, YAKURI, 98.0%) and 0.739 g of citric
acid (YAKURI, 99.99%) at the same molar equivalent as cerium
nitrate were mixed with each other, and then a cerium precursor and
citric acid which were weighed so as to correspond to the pore
volume of 2.7 g of silica (SYLOPOL, SP948) as a carrier were
dissolved in distilled water. Then, the precursor solution thus
prepared was added to 2.7 g of the silica carrier and the solution
was allowed to be absorbed into the pores of the carrier by
stirring. Thereafter, distilled water remaining in the pores was
completely removed by drying in an oven at 110.degree. C. for 5
hours or longer. A phosphate solution prepared by dissolving 2.294
g of phosphate (H.sub.3PO.sub.4 DAEJUNG, 85%) at an equivalent
weight of 2 in distilled water in a volume corresponding to the
pore volume of the carrier was also supported in the same manner,
and dried in an oven at 110.degree. C. for 12 hours or longer, and
then calcined in a furnace under air atmosphere at 800.degree. C.
for 4 hours to prepare a 15 wt % CePO.sub.4/SiO.sub.2 catalyst.
Examples 3 to 5
[0042] A 15 wt % CePO.sub.4/SiO.sub.2 catalyst was prepared in the
same manner as in the method for preparing the supported catalyst
of Example 2, except that the molar ratio of cerium nitrate and
phosphate was changed to 1:3 (Example 3) or 1:4 (Example 4).
Comparative Example 1
[0043] A predetermined amount (7.723 g) of cerium nitrate
(Ce(NO.sub.3).sub.2.6H.sub.2O, YAKURI, 98.0%) was dissolved in 20
ml of distilled water in a beaker so as to prepare a cerium
precursor solution. Then, a NH.sub.3OH solution was added dropwise
to the solution at room temperature while stirring to maintain the
solution at pH of 8.5. When NH.sub.3OH (DAEJUNG, 85%) solution was
dripped therein, cerium hydroxide particles were formed to obtain a
solution in the slurry type. The solution was stirred for 8 hours,
and then 2.211 g of a phosphate (H.sub.3PO.sub.4 DAEJUNG, 85%)
solution was added dropwise. Then, the cerium hydroxide precursor
and the phosphate solution were allowed to form a phosphorus oxide
solution by stirring for 5 hours. While the solution was washed
with distilled water, NH.sub.3OH in the catalyst precursor was
removed by filtering, and then the resulting precursor was dried in
an oven at 110.degree. C. for about 12 hours and calcined under air
atmosphere at 800.degree. C. for 4 hours to prepare a CePO.sub.4
catalyst.
Comparative Example 2
[0044] A CePO.sub.4 catalyst was prepared in the same manner as in
Comparative Example 1, except that (NH.sub.3).sub.2PO.sub.4 was
used instead of phosphate (H.sub.3PO.sub.4).
Comparative Example 3
[0045] A CePO.sub.4 catalyst was prepared in the same manner as in
Comparative Example 1, except that (C.sub.2H.sub.5).sub.3PO.sub.4
was used instead of phosphate (H.sub.3PO.sub.4).
Comparative Example 4
[0046] A 15 wt % CePO.sub.4/SiO.sub.2 catalyst was prepared in the
same manner as in the method for preparing the supported catalyst
of Example 2, except that the molar ratio of cerium nitrate and
phosphate was changed to 1:1.1.
Comparative Example 5
[0047] A 15 wt % CePO.sub.4/SiO.sub.2 catalyst was prepared in the
same manner as in the method for preparing the supported catalyst
of Example 3, except that no citric acid was added.
TABLE-US-00001 TABLE 1 Preparation method of bulk catalyst
Preparation method of catalyst Type of phosphate Example 1 Citric
acid sol-gel H.sub.3PO.sub.4 method Comparative NH.sub.3OH sol-gel
H.sub.3PO.sub.4 Example 1 method Comparative NH.sub.3OH sol-gel
(NH.sub.3).sub.2PO.sub.4 Example 2 method Comparative NH.sub.3OH
sol-gel (C.sub.2H.sub.5).sub.3PO.sub.4 Example 3 method
TABLE-US-00002 TABLE 2 Preparation method of SiO.sub.2-supported
catalyst Molar ratio of Ce:P Additive Solvent Example 2 1:2 Citric
acid Water Example 3 1:3 Citric acid Water Example 4 1:4 Citric
acid Water Example 5 1:5 Citric acid Water Comparative 1:1.1 Citric
acid Water Example 4 Comparative 1:3 None Water Example 5
Comparative 1:3 Citric acid Ethanol Example 6
Experimental Example
Glycerin Conversion Ratio, and Acrolein and By-Product
Selectivity
[0048] Acrolein was produced from glycerin using the catalysts
prepared in the examples and comparative examples, and an HTS
(high-throughput screening) apparatus which was manufactured to
evaluate performance with a small amount of the catalyst for a
short time under the conditions described in the following Table 3
was used. The products were analyzed in-situ by GC to calculate the
conversion ratio, selectivity, and yield. The glycerin conversion
ratio and acrolein selectivity are shown in the following Tables 4
and 5.
[0049] Herein, the glycerin conversion ratio represents a ratio of
glycerin to other compounds converted therefrom, and the acrolein
selectivity represents a proportion of acrolein in the converted
compounds.
[0050] Further, Comparative Selectivity 1 represents a comparison
of the selectivity of hydroxy acetone to the selectivity of
acrolein and the selectivity of a compound having a molecular
weight of 130, and Comparative Selectivity 2 represents a
comparison of the selectivity of by-product to the selectivity of
acrolein and the selectivity of a compound having a molecular
weight of 130. In Comparative Selectivity 1 and 2, hydroxy acetone
is the major by-product of glycerin dehydration, and the by-product
includes hydroxy acetone, aryl alcohol, acetol, propionic acid,
1,2-propanediol, 1,3-propanediol, and cyclic acetal compounds
produced by double condensation/dehydration between glycerin
molecules or between acetol and glycerin. In the selectivity of the
compound having a molecular weight of 130, the compound having a
molecular weight of 130 is a cyclic acetal compound produced by
dehydration of acrolein and glycerin, and is a by-product produced
in the rear part of the reactor by heating at 200.degree. C.
TABLE-US-00003 TABLE 3 Conditions for glycerin dehydration Reaction
pressure 1 atm Reaction temperature 280.degree. C. Feed rate of
reactant 3.5 ml/h Reaction time 1 hour Glycerin concentration 28.08
wt % WHSV (weight hourly space 113.03 mmol/(h g.sub.cat) velocity)
Catalyst amount 0.1 g
TABLE-US-00004 TABLE 4 Glycerin conversion ratio, and Acrolein and
Hydroxy acetone selectivity Molecular Glycerin Acrolein weight 130
conversion selectivity Hydroxy acetone selectivity Example ratio
(%) (%) selectivity (%) (%) Example 1 16.2 18.74 36.11 13.28
Example 2 4.21 18.51 28.00 14.29 Example 3 16.59 19.39 20.33 19.70
Example 4 9.30 16.99 27.74 12.75 Example 5 13.82 21.56 25.51 16.05
Comparative 1.22 6.72 44.77 7.14 Example 1 Comparative 0.75 6.04
37.84 7.80 Example 2 Comparative 0.78 5.09 25.01 4.64 Example 3
Comparative 3.74 6.31 10.22 9.13 Example 4 Comparative 5.40 14.98
20.38 16.35 Example 5 Comparative 9.80 9.97 13.98 16.74 Example
6
TABLE-US-00005 TABLE 5 Comparative selectivity of by-product to
acrolein selectivity *Comparative **Comparative Example Selectivity
1 Selectivity 2 Example 1 1.93 2.73 Example 2 1.51 2.54 Example 3
1.05 2.06 Example 4 1.63 2.97 Example 5 1.18 2.09 Comparative 6.67
9.14 Example 1 Comparative 6.26 9.57 Example 2 Comparative 4.91
12.33 Example 3 Comparative 1.62 7.66 Example 4 Comparative 1.36
3.01 Example 5 Comparative 1.40 4.22 Example 6 *Comparative
Selectivity 1 = Selectivity of hydroxy acetone/(Selectivity of
acrolein + Selectivity of a compound having a molecular weight of
130) **Comparative Selectivity 2 = Selectivity of
by-product/(Selectivity of acrolein + Selectivity of a compound
having a molecular weight of 130)
[0051] As shown in Tables 4 and 5, when glycerin was reacted using
the catalysts of the examples which were prepared by using the
cerium precursor and the phosphorus precursor, and citric acid, the
glycerin conversion ratio and the acrolein selectivity were
remarkably increased, compared to use of the catalysts of the
comparative examples which were prepared by using an alkaline
compound such as NH.sub.3OH, instead of citric acid.
[0052] Further, Comparative Selectivity 1 or 2 which is a
comparison of the selectivity of by-products to the selectivity of
acrolein which is the desired main product in the above reaction
was lower than those obtained by using the catalysts of the
comparative examples.
[0053] That is, these results showed that the catalysts for
glycerin dehydration of the examples are able to produce acrolein
from glycerin with high selectivity and high purity, and to inhibit
production of by-products such as hydroxy acetone.
* * * * *