U.S. patent application number 14/718533 was filed with the patent office on 2015-09-10 for method for making a catalyst comprising a phosphorus modified zeolite to be used in an alcohols dehydration process.
The applicant listed for this patent is TOTAL RESEARCH & TECHNOLOGY FELUY. Invention is credited to Jean-Pierre Dath, Delphine Minoux, Nikolai Nesterenko, Sander Van Donk.
Application Number | 20150251970 14/718533 |
Document ID | / |
Family ID | 42243450 |
Filed Date | 2015-09-10 |
United States Patent
Application |
20150251970 |
Kind Code |
A1 |
Nesterenko; Nikolai ; et
al. |
September 10, 2015 |
Method for Making a Catalyst Comprising a Phosphorus Modified
Zeolite to be Used in an Alcohols Dehydration Process
Abstract
A method of forming a phosphorus modified zeolite includes
introducing phosphorus into a zeolite having at least one ten
member ring in a structure thereof in an amount of from 0.5 to 30
weight percent, followed by a separation of solid from liquid if
any. The method includes mixing the phosphorus modified zeolite
with a component selected among binders, salts of alkali-earth
metals, salts of rare-earth metals, and clays. The method includes
making a catalyst body from the mixture by extruding the mixture
into a desired shape. The method optionally includes a drying step,
optionally followed by a washing step. The method includes a
calcination step, optionally followed by a washing step and drying.
An alcohol having at least 2 carbon atoms may be converted into a
corresponding olefin in a dehydration process in the presence of
the phosphorus modified zeolite.
Inventors: |
Nesterenko; Nikolai;
(Nivelles, BE) ; Van Donk; Sander;
(Sainte-Adresse, FR) ; Minoux; Delphine;
(Nivelles, BE) ; Dath; Jean-Pierre; (Beloeil,
BE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TOTAL RESEARCH & TECHNOLOGY FELUY |
SENEFFE (FELUY) |
|
BE |
|
|
Family ID: |
42243450 |
Appl. No.: |
14/718533 |
Filed: |
May 21, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13522633 |
Sep 28, 2012 |
9067199 |
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PCT/EP2011/050964 |
Jan 25, 2011 |
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14718533 |
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Current U.S.
Class: |
585/640 ;
502/71 |
Current CPC
Class: |
B01J 2229/37 20130101;
C07C 1/20 20130101; B01J 2229/36 20130101; B01J 2229/18 20130101;
B01J 29/40 20130101; B01J 37/0009 20130101; B01J 37/0045 20130101;
C07C 2529/40 20130101; B01J 29/06 20130101; B01J 37/28 20130101;
B01J 2229/42 20130101; C07C 1/20 20130101; B01J 29/85 20130101;
B01J 37/08 20130101; B01J 37/06 20130101; C07C 1/24 20130101; B01J
27/16 20130101; C07C 2529/85 20130101; C07C 11/02 20130101 |
International
Class: |
C07C 1/24 20060101
C07C001/24; B01J 37/06 20060101 B01J037/06; B01J 37/08 20060101
B01J037/08; B01J 29/85 20060101 B01J029/85; B01J 37/00 20060101
B01J037/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 25, 2010 |
EP |
10151507.0 |
Claims
1. A method comprising: converting an alcohol having at least 2
carbon atoms into a corresponding olefin in a dehydration process,
wherein conversion of the alcohol is performed in the presence of a
catalyst, wherein said catalyst comprises a phosphorus modified
zeolite that is made by a method comprising the following steps in
this order: a) introducing phosphorus into a zeolite comprising at
least one ten member ring in a structure thereof in an amount of
from 0.5 to 30 weight percent, followed by a separation of solid
from liquid if any, b) mixing the phosphorus modified zeolite of
step a) with at least a component selected among one or more
binders, salts of alkali-earth metals, salts of rare-earth metals,
and clays, b)* making a catalyst body from the mixture of step b)
by extruding the mixture into a desired shape, c) an optional
drying step or an optional drying step followed by a washing step,
d) a calcination step, d*) an optional washing step followed by
drying.
2. (canceled)
3. The method according to claim 1, wherein the amount of
phosphorous introduced into the zeolite at step a) is from 0.5 to 9
wt %.
4. The method according to claim 1, wherein the zeolite contains
less than 1000 wppm of sodium, less than 1000 wppm of potassium and
less than 1000 wppm of iron.
5. The method according to claim 1, wherein the zeolite contains
less than 100 ppm of red-ox and noble elements.
6. The method according to claim 1, wherein alkali-earth metals and
salts of rare-earth metals are Ca, Mg, Sr, Ce, La or a combination
thereof.
7. The method according to claim 1, wherein the zeolite structure
is selected from the MFI, MTT, FER, MEL, TON, MWW, EUO, MFS,
ZSM-48.
8. The method according to claim 1, wherein the proportion of the
phosphorus modified zeolite is from 15 to 90 wt % of the
catalyst.
9. The method according to claim 1, wherein a concentration of the
salts of alkali-earth metals and salts of rare-earth metals is from
0.1 to 15 wt % of the catalyst on metal basis (Me).
10. The method according to claim 8 wherein a molar ratio of
(Al+Me)/P in the catalyst is in the range 0.5 to 3, where the Me is
alkali or rare-earth, P is phosphorus, and Al is aluminum.
11. The method according to claim 1, wherein the from 0.5 to 30
weight percent of the phosphorus introduced in step a) is
introduced into the zeolite prior to introduction of any binder to
the zeolite.
12. The method according to claim 1, wherein the from 0.5 to 30
weight percent of the phosphorus introduced in step a) is
introduced into the zeolite prior to introduction of any salts of
alkali-earth metals to the zeolite.
13. The method according to claim 1, wherein the from 0.5 to 30
weight percent of the phosphorus introduced in step a) is
introduced into the zeolite prior to introduction of any salts of
rare-earth metals to the zeolite.
14. The method according to claim 1, wherein the from 0.5 to 30
weight percent of the phosphorus introduced in step a) is
introduced into the zeolite prior to introduction of any clays to
the zeolite.
15. The method according to claim 1, wherein the from 0.5 to 30
weight percent of the phosphorus introduced in step a) is
introduced into the zeolite prior to introduction of any shaping
additives to the zeolite.
16. The method according to claim 1, wherein a P/Al ratio in step
a) is higher than 1, wherein P is phosphorus and Al is
aluminum.
17. The method according to claim 1, wherein, prior to introduction
of the phosphorus into the zeolite, the zeolite is steamed, or
steamed and then leached.
18. The method according to claim 1, wherein, prior to introduction
of the phosphorus, the zeolite has a silicon to aluminum ratio that
is below 20.
19. A method comprising the following steps in this order: a)
introducing phosphorus into a zeolite comprising at least one ten
member ring in a structure thereof in an amount of from 0.5 to 30
weight percent, followed by a separation of solid from liquid if
any, to form a phosphorus modified zeolite, b) mixing the
phosphorus modified zeolite of step a) with at least a component
selected among one or more binders, salts of alkali-earth metals,
salts of rare-earth metals, and clays, b)* making a catalyst body
from the mixture of step b) by extruding the mixture into a desired
shape, c) an optional drying step or an optional drying step
followed by a washing step, d) a calcination step, d*) an optional
washing step followed by drying.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a method for making a
catalyst comprising a phosphorus modified zeolite to be used to
convert an alcohol into light olefins in a dehydration process to
convert at least an alcohol into the corresponding olefin wherein
said catalyst comprises a phosphorus modified zeolite. Olefins are
traditionally produced from petroleum feedstocks by catalytic or
steam cracking processes. These cracking processes, especially
steam cracking, produce light olefin(s), such as ethylene and/or
propylene, from a variety of hydrocarbon feedstock. Ethylene and
propylene are important commodity petrochemicals useful in a
variety of processes for making plastics and other chemical
compounds.
[0002] The limited supply and increasing cost of crude oil has
prompted the search for alternative processes for producing
hydrocarbon products.
[0003] Olefins can be produced by dehydration of the corresponding
alcohol. Ethanol, as well as higher alcohols such as propanol,
butanol can be obtained by fermentation of carbohydrates. Made up
of organic matter from living organisms, biomass is the world's
leading renewable energy source. Recently, new routes to produce
ethanol and higher alcohols from syngas have been described.
BACKGROUND OF THE INVENTION
[0004] Catalysts comprising a phosphorus modified zeolite (the
phosphorus modified zeolite is also referred as P-zeolite) are
known. The following prior arts have described various methods to
make said catalysts.
[0005] US 2006 106270 relates to the use of a dual-function
catalyst system in the hydrocarbon synthesis reaction zone of an
oxygenate to propylene (OTP) process that operates at relatively
high temperatures preferably with a steam diluent and uses moving
bed reactor technology. The dual-functional catalyst system
comprises a molecular sieve having dual-function capability
dispersed in a phosphorus-modified alumina matrix containing labile
phosphorus and/or aluminum anions. It is explained that the
hydrothermal stabilization effect that is observed when this
phosphorus-modifed alumima matrix is utilized is caused by
migration or dispersion of phosphorus and/or aluminum anions from
this matrix into the bound molecular sieve. These anions are then
available to repair, anneal and/or stabilize the framework of the
molecular sieve against the well-known dealumination mechanism of
molecular sieve framework destruction or modification that is
induced by exposure to steam at temperatures corresponding to those
used in the OTP reaction zone and in the regeneration zone.
[0006] U.S. Pat. No. 4,356,338 discloses a method for decreasing
catalyst coking and extending the usable catalyst life by
pre-treatment of the catalyst with steam and/or a
phosphorus-containing compound. Pretreatment may be accomplished by
the impregnation of the catalyst or of the catalyst/binder
combination with a phosphorus containing compound to deposit
approximately 4 wt. % of phosphorus thereon, and preferably from
about 2% to about 15% by weight of phosphorus, based on the weight
of the catalyst or catalyst/binder matrix being treated.
[0007] U.S. Pat. No. 5,231,064 is directed to a fluid catalyst
comprising clay and a zeolite, at least one of which has been
treated with a phosphorus containing compound, for example ammonium
dihydrogen phosphate or phosphoric acid, and which is spray dried
at a low pH, preferably lower than about 3. Said catalysts are
deemed to advantageously exhibit reduced attrition.
[0008] EP 511013 A2 provides an improved process for the production
of C2-05 olefins from higher olefinic or paraffinic or mixed olefin
and paraffin feedstocks. In accordance with this prior art, the
hydrocarbon feed materials are contacted with a particular ZSM-5
catalyst at elevated temperatures, high space velocity and low
hydrocarbon partial pressure to produce lower olefins. The
catalysts is treated with steam prior to use in the hydrocarbon
conversion. The active catalyst component is phosphorus-containing
ZSM-5 having a surface Si/Al ratio in the range 20-60. Preferably,
the phosphorus is added to the formed ZSM-5 as by impregnating the
ZSM-5 with a phosphorus compound in accordance with the procedures
described, for example, in U.S. Pat. No. 3,972,832. Less
preferably, the phosphorus compound can be added to the
multicomponent mixture from which the catalyst is formed. The
phosphorus compound is added in amount sufficient to provide a
final ZSM-5 composition having 0.1-10 wt. % phosphorus, preferably
1-3 wt. %.
[0009] The phosphorus-containing ZSM-5 is preferably combined with
known binders or matrices such as silica, kaolin, calcium
bentonite, alumina, silica aluminate and the like. The ZSM-5
generally comprises 1-50 wt. % of the catalyst composition,
preferably 5-30 wt. % and most preferably 10-25 wt. %.
[0010] EP 568913 A2 describes a method for preparing a ZSM-5 based
catalyst adapted to be used in the catalytic conversion of methanol
or dimethyl ether to light olefins, wherein it comprises the
following consecutive steps: [0011] mixing a zeolite ZSM-5 based
catalyst with silica sol and ammonium nitrate solution, [0012]
kneading, moulding, drying and calcining the mixture, [0013]
exchanging the modified zeolite with a solution of HCl at
70-90.degree. C., [0014] drying and calcining the H-modified
zeolite, [0015] impregnating the H-modified zeolite with phosphoric
acid under reduced pressure, [0016] drying and calcining the
P-modified zeolite, [0017] impregnating the P-modified zeolite with
a solution of rare earth elements under reduced pressure, [0018]
drying and calcining the P-rare earths-modified zeolite, [0019]
hydrothermally treating the P-rare earths-modified zeolite at
500-600.degree. C. with water vapour, and [0020] calcining the
modified zeolite.
[0021] WO 03 020667 relates to a process of making olefin,
particularly ethylene and propylene, from an oxygenate feed,
comprising contacting an oxygenate feed with at least two different
zeolite catalysts to form an olefin composition, wherein a first of
the zeolite catalysts contains a ZSM-5 molecular sieve and a second
of the zeolite catalysts contains a zeolite molecular sieve
selected from the group consisting of ZSM-22, ZSM-23, ZSM-35,
ZSM-48, and mixtures thereof. The ZSM-5 can be unmodified,
phosphorous modified, steam modified having a micropore volume
reduced to not less than 50% of that of the unsteamed ZSM-5, or
various mixtures thereof. According to one embodiment, the zeolite
is modified with a phosphorous containing compound to control
reduction in pore volume. Alternatively, the zeolite is steamed,
and the phosphorous compound is added prior to or after steaming.
The amount of phosphorous, as measured on an elemental basis, is
from 0.05 wt. % to 20 wt. %, and preferably is from 1 wt. % to 10
wt. %, based on the weight of the zeolite molecular sieve.
Preferably, the atomic ratio of phosphorus to framework aluminum
(i.e. in the zeolite framework) is not greater than 4:1 and more
preferably from 2:1 to 4:1. Incorporation of a phosphorus modifier
into the catalyst of the invention is accomplished, according to
one embodiment, by contacting the zeolite molecular sieve either
alone or the zeolite in combination with a binder with a solution
of an appropriate phosphorus compound. The solid zeolite or zeolite
catalyst is separated from the phosphorous solution, dried and
calcined. In some cases, the added phosphorous is converted to its
oxide form under such conditions. Contact with the
phosphorus-containing compound is generally conducted at a
temperature from 25.degree. C. to 125.degree. C. for a time from 15
minutes to 20 hours. The concentration of the phosphorus in the
zeolite may be from 0.01 wt. % to 30 wt. %. This prior art
discloses a non-formulated P-ZSM-5.
[0022] A common way to produce a formulated P-zeolite containing
catalyst consists in the impregnation of the already pre-formulated
zeolite (e.g. the zeolite+a binder) with P-compounds or phosphorous
addition to the reaction medium.
[0023] A great number of patents disclose the recipe for
preparation of the active phase (non-formulated phosphated zeolite)
by means of zeolite phosphatation and their use in methanol
conversion. Some of these references contain the options of further
blending the active phase with binder. However, the active phase is
good as such in the reaction. It is assumed that the binder plays
only the role of diluent what is not normally the case. The process
of the present invention differs from a great number of known in
the art preparation of the P-zeolite based active phase due to
referring to preparation of formulated catalyst and implementation
of the phosphatation step at the first stage. Moreover the
phosphatation of the zeolite (formation of the active phase) at the
first step does not necessarily leads to a suitable catalyst. On
the contrary, the overall recipe results in a good catalyst.
[0024] The catalyst referred to in the present invention comprises
a zeolite and at least a component selected among one or more
binders, salts of alkali-earth metals, salts of rare-earth metals,
clays and shaping additives. The metal salts, binder and clays may
also adsorb the phosphorous interfering and even competing with
zeolite preventing a proper zeolite phosphatation. The presence of
traces of metals adsorbing preferentially phosphorous could even
more perturb the zeolite phophatation. This often leads to
non-selective catalysts due to poor reproducibility and binder pore
plugging. The method of the present invention provides a solution
to selectively phosphatize zeolite overcoming the side effects of
binder, metal salts or clays presence. Thus, the invention
discloses that the preparation of the catalyst requires the
phosphatation of zeolite before introducing any other components
such as binder, metals, clays and shaping additives. This method
insures the reproducibility of the preparation, the hydrothermal
stability and the good catalyst performance.
BRIEF DESCRIPTION OF THE INVENTION
[0025] The present invention relates to the use of a catalyst to
convert at least an alcohol into light olefins in a dehydration
process wherein said catalyst comprises a phosphorus modified
zeolite and is made by a method comprising the following steps in
this order,
a) the essential portion of the phosphorus is introduced into a
zeolite comprising at least one ten members ring in the structure,
b) the phosphorus modified zeolite of step a) is mixed with at
least a component selected among one or more binders, salts of
alkali-earth metals, salts of rare-earth metals, clays and shaping
additives, b)* making a catalyst body from mixture b), c) an
optional drying step or an optional drying step followed by a
washing step, d) a calcination step, d*) an optional washing step
followed by drying, e) optionally a small portion of phosphorus is
introduced in the course of step b) or b)* or at end of step b) or
b)*.
[0026] Advantageously the zeolite (or molecular sieve) contains
less that 1000 wppm of sodium, less that 1000 wppm of potassium and
less that 1000 wppm of iron.
[0027] Advantageously the zeolite contains less than 200 ppm of
alkali and alkali-earth metals.
[0028] Advantageously the bulk Si/Al ratio of initial zeolite is
below 20. Advantageously the zeolite contains less than 100 ppm of
red-ox and noble elements such as Zn, Cr, Ti, Rh, Mn, Ni, V, Mo,
Co, Cu, Cd, Pt, Pd, Ir, Ru, Re.
[0029] The phosphorus source is advantageously substantially free
of metal compounds. It is advantageously selected among H3PO4,
ammonium phosphates or organic P-compounds.
[0030] In an embodiment the phosphorus of step e) can be introduced
as a component of the binder or of the clays.
[0031] The amount of phosphorous introduced into the zeolite at
step a) can be from 0.5 to 30 wt %, but preferably from 0.5 to
9%.
[0032] Advantageously the molar P/Al ratio at step a) is higher
than 1 by providing the excess of phosphatation agent.
[0033] The formulation steps b) and c) can be performed by means of
spray--drying, extrusion, oil drop etc.
[0034] In accordance with the present invention, at the step c) and
d*) the catalyst is treated with water for a period of time
advantageously from 0.5 to 48 hours, preferably for a period of
time from about 1 to 36 hours and most preferably from about 2 to
24 hours. The water is at a temperature between about 10.degree.
and 180.degree. C., preferably between about 15.degree. and
100.degree. C. and most preferably between about 20.degree. and
60.degree. C. Following the water treatment, the catalyst is dried
at about 60-350.degree. C. Optionally, the water can contain
ammonium or/and at least one of the ions selected from the group
consisting of Li, Ag, Mg, Ca, Sr, Ba, Ce, Al, La, and mixtures
thereof.
[0035] At end of step a) it is not mandatory to separate the
P-zeolite from the reaction medium, the binders, salts of
alkali-earth metals, salts of rare-earth metals, clays and shaping
additives can be added directly into the reaction medium.
[0036] In a preferred embodiment, a low sodium content binder and
clays are used.
[0037] Before the phosphatation of step a) the zeolite can be
subjected to various treatments including, ion exchange, steaming,
acid treatment, surface passivating by silica deposition etc.
[0038] In a preferred embodiment the sodium content in the binder
and the clays is less that 5000 ppm of sodium.
[0039] Preferred zeolite structures are selected from the MFI, MTT,
FER, MEL, TON, MWW, EUO, MFS, ZSM-48.
BRIEF DESCRIPTION OF THE FIGURES
[0040] FIG. 1 shows the evolution of the ethanol conversion (full
rectangles) and the ethylene yield (open lozenges) as a function of
time of stream. Catalyst A. Surfin 96 bio-ethanol--400.degree.
C.--2 bara--WHSV (Ethanol): 7 h-1
[0041] FIG. 2 shows the evolution of the ethanol conversion (full
rectangles) and the ethylene yield (open circles) as a function of
time of stream. Catalyst B. Surfin 96 bio-ethanol diluted with 5 wt
% water--360.degree. C.--2 bara--WHSV (Ethanol): 7 h-1
DETAILED DESCRIPTION OF THE INVENTION
[0042] As regards the dehydration process to convert an alcohol
into an olefin, this process has been described in a lot of patent
applications. One can cite WO/2009/098262, WO/2009/098267,
WO/2009/098268 and WO 2009/098269, the content of which is
incorporated in the present application. The alcohol is any alcohol
provided it can be dehydrated to the corresponding olefin. By way
of example mention may be made of alcohols having from 2 to 10
carbon atoms. Advantageously the invention is of interest for
ethanol, propanol, butanol and phenylethanol.
[0043] As regards the zeolite containing at least one 10 members
ring into the structure, one can cite the crystalline silicates. It
is by way of example of the MFI (ZSM-5, silicalite-1, boralite C,
TS-1), MEL (ZSM-11, silicalite-2, boralite D, TS-2, SSZ-46), FER
(Ferrierite, FU-9, ZSM-35), MTT (ZSM-23), MWW (MCM-22, PSH-3,
ITQ-1, MCM-49), TON (ZSM-22, Theta-1, NU-10), EUO (ZSM-50, EU-1),
MFS (ZSM-57) and ZSM-48 family of microporous materials consisting
of silicon, aluminium, oxygen and optionally boron.
[0044] The three-letter designations "MFI" and "MEL" each
representing a particular crystalline silicate structure type as
established by the Structure Commission of the International
Zeolite Association. Examples of a crystalline silicate of the MFI
type are the synthetic zeolite ZSM-5 and silicalite and other MFI
type crystalline silicates known in the art. Examples of a
crystalline silicate of the MEL family are the zeolite ZSM-11 and
other MEL type crystalline silicates known in the art. Other
examples are Boralite D and silicalite-2 as described by the
International Zeolite Association (Atlas of zeolite structure
types, 1987, Butterworths). The preferred crystalline silicates
have pores or channels defined by ten oxygen rings.
[0045] Crystalline silicates are microporous crystalline inorganic
polymers based on a framework of XO.sub.4 tetrahedra linked to each
other by sharing of oxygen ions, where X may be trivalent (e.g. Al,
B, . . . ) or tetravalent (e.g. Ge, Si, . . . ). The crystal
structure of a crystalline silicate is defined by the specific
order in which a network of tetrahedral units are linked together.
The size of the crystalline silicate pore openings is determined by
the number of tetrahedral units, or, alternatively, oxygen atoms,
required to form the pores and the nature of the cations that are
present in the pores. They possess a unique combination of the
following properties: high internal surface area; uniform pores
with one or more discrete sizes; ion exchangeability; good thermal
stability; and ability to adsorb organic compounds. Since the pores
of these crystalline silicates are similar in size to many organic
molecules of practical interest, they control the ingress and
egress of reactants and products, resulting in particular
selectivity in catalytic reactions. Crystalline silicates with the
MFI structure possess a bidirectional intersecting pore system with
the following pore diameters: a straight channel along
[010]:0.53-0.56 nm and a sinusoidal channel along [100]:0.51-0.55
nm. Crystalline silicates with the MEL structure possess a
bidirectional intersecting straight pore system with straight
channels along [100] having pore diameters of 0.53-0.54 nm.
[0046] In a specific embodiment the crystalline silicate is steamed
to remove aluminium from the crystalline silicate framework before
phosphatation. The steam treatment is conducted at elevated
temperature, preferably in the range of from 425 to 870.degree. C.,
more preferably in the range of from 540 to 815.degree. C. and at
pressure 1-5 bara and at a water partial pressure of from 13 to 200
kPa. Preferably, the steam treatment is conducted in an atmosphere
comprising from 5 to 100% steam. The steam atmosphere preferably
contains from 5 to 100 vol % steam with from 0 to 95 vol % of an
inert gas, preferably nitrogen. A more preferred atmosphere
comprises 72 vol % steam and 28 vol % nitrogen i.e. 72 kPa steam at
a pressure of one atmosphere. The steam treatment is preferably
carried out for a period of from 1 to 200 hours, more preferably
from 20 hours to 100 hours. As stated above, the steam treatment
tends to reduce the amount of tetrahedral aluminium in the
crystalline silicate framework, by forming alumina.
[0047] Additionally, if during the preparation of the zeolite to be
phosphatized alkaline or alkaline earth metals have been used, the
molecular sieve might be subjected to an ion-exchange step.
Conventionally, ion-exchange is done in aqueous solutions using
ammonium salts or inorganic acids.
[0048] As regards the introduction of P into the zeolite, by way of
example said P-modified zeolite is made by a process comprising in
that order: [0049] introducing P; [0050] separation of the solid
from the liquid if any; [0051] an optional washing step or an
optional drying step or an optional drying step followed by a
washing step; [0052] a calcination step;
[0053] Optionally, the contact with the phosphorus-containing
compound is conducted at a temperature from 40.degree. C. to
110.degree.. P can be introduced by any means or, by way of
example, according to the recipe described in U.S. Pat. No.
3,911,041.
[0054] The separation of the liquid from the solid is
advantageously made by filtering at a temperature between
0-90.degree. C., centrifugation at a temperature between
0-90.degree. C., evaporation or equivalent.
[0055] Optionally, the zeolite can be dried after separation before
washing. Advantageously said drying is made at a temperature
between 40-600.degree. C., advantageously for 1-10 h. This drying
can be processed either in a static condition or in a gas flow.
Air, nitrogen or any inert gases can be used.
[0056] The washing step can be performed either during the
filtering (separation step) with a portion of cold (<40.degree.
C.) or hot water (>40 but<90.degree. C.) or the solid can be
subjected to a water solution (1 kg of solid/4 liters water
solution) and treated under reflux conditions for 0.5-10 h followed
by evaporation or filtering.
[0057] According to a specific embodiment the phosphorous modified
zeolite is made by a process comprising in that order: [0058]
selecting a zeolite; [0059] steaming at a temperature ranging from
400 to 870.degree. C. for 0.01-200 h; [0060] optional leaching with
an aqueous acid solution at conditions effective to remove a
substantial part of Al from the zeolite; [0061] introducing P with
an aqueous solution containing the source of P at conditions
effective to introduce advantageously at least 0.05 wt % of P;
[0062] separation of the solid from the liquid; [0063] an optional
washing step or an optional drying step or an optional drying step
followed by a washing step; [0064] an optional calcination
step.
[0065] In the steam treatment step, the temperature is preferably
from 420 to 870.degree. C., more preferably from 480 to 760.degree.
C. The pressure is preferably atmospheric pressure and the water
partial pressure may range from 13 to 100 kPa. The steam atmosphere
preferably contains from 5 to 100 vol % steam with from 0 to 95 vol
% of an inert gas, preferably nitrogen. The steam treatment is
preferably carried out for a period of from 0.01 to 200 hours,
advantageously from 0.05 to 200 hours, more preferably from 0.05 to
50 hours. The steam treatment tends to reduce the amount of
tetrahedral aluminium in the crystalline silicate framework by
forming alumina.
[0066] The leaching can be made with an organic acid such as citric
acid, formic acid, oxalic acid, tartaric acid, malonic acid,
succinic acid, glutaric acid, adipic acid, maleic acid, phthalic
acid, isophthalic acid, fumaric acid, nitrilotriacetic acid,
hydroxyethylenediaminetriacetic acid, ethylenediaminetetracetic
acid, trichloroacetic acid trifluoroacetic acid or a salt of such
an acid (e.g. the sodium salt) or a mixture of two or more of such
acids or salts. The other inorganic acids may comprise an inorganic
acid such as nitric acid, hydrochloric acid, methansulfuric acid,
phosphoric acid, phosphonic acid, sulfuric acid or a salt of such
an acid (e.g. the sodium or ammonium salts) or a mixture of two or
more of such acids or salts.
[0067] The residual P-content is adjusted by P-concentration in the
aqueous acid solution containing the source of P, drying conditions
and a washing procedure if any. A drying step can be envisaged
between filtering and washing steps.
[0068] As regards step b), and the binder, it is selected so as to
be resistant to the temperature and other conditions employed in
the processes using the catalyst. The binder is an inorganic
material selected from silica, metal silicates, metal oxides such
as Zr0.sub.2 and/or metals, or gels including mixtures of silica
and metal oxides. It is desirable to provide a catalyst having a
good crush strength. This is because in commercial use, it is
desirable to prevent the catalyst from breaking down into
powder-like materials. Such oxide binders have been employed
normally only for the purpose of improving the crush strength of
the catalyst. A particularly preferred binder for the catalyst of
the present invention comprises silica. The relative proportions of
the finely divided crystalline silicate material and the inorganic
oxide matrix of the binder can vary widely.
[0069] As regards step b)*, in addition to enhancing the catalyst
strength properties, the matrix material allows the molecular sieve
crystallite powder to be bound into larger particle sizes suitable
for commercial catalytic processes. The formulation of the mixture
b) may be formed into a wide variety of shapes including
extrudates, spheres, pills, and the like. The binder material is
often, to some extent, porous in nature and may or may not be
effective to promote the desired conversion of methanol to light
olefins. The matrix material may also promote conversion of the
feed stream and often provides reduced selectivity to the desired
product or products relative to the catalyst.
[0070] Types of silica sols used to form a bound catalyst for use
in alcohol dehydration process are commercially available as
aquasols or organosols containing dispersed colloidal silica
particles. For example, sodium silicate can be used as a silica
sol. Otherwise, a silica gel, fumed or pyrogenic silica may also be
used to provide a silica binder in the molecular sieve catalyst.
Silicic acid is another possible source of silica. If a magnesia
binder is desired, the starting slurry will contain hydrolyzed
magnesium alkoxide. When a zirconia binder is used for the catalyst
preparation, the preferred starting acidic sol is an aqueous
zirconium acetate solution, which is preferably combined with a
urea gelling agent. Advantageously, the binder contains low amount
of sodium below 1000 ppm.
[0071] As regards to the clays, It is preferred to optionally add a
clay to the catalyst. The clay is usually added to the catalyst
slurry before the mixing of the molecular sieve and binder, and the
resultant slurry is mixed and spray dried. Clays that are used in
this process to form a hardened product include, but are not
limited to, kaolin, kaolinite, montmorillonite, saponite,
bentonite, attapulgite and halloysite. Clays contribute to strength
as a binder enhancing the attrition resistance properties of the
catalyst particles, and clays in combination with binders
contribute to the hardness of the particles. Clays also start as
small particles and have a higher density, such that when combined
with the molecular sieve and binder provide for denser particles,
imparting the desirable characteristic of higher density.
[0072] As regards the salts of alkali-earth metals, salts of
rare-earth metals, the metals are advantageously Ca, Mg, Sr, Ce, La
or a combination thereof.
[0073] As regards the proportions of the P-zeolite, the one or more
binders, salts of alkali-earth metals, salts of rare-earth metals,
clays and shaping additives, advantageously the proportion of the
P-zeolite is from 5 to 95 w % of the catalyst. The catalyst
comprises the P-zeolite and at least a component selected among one
or more binders, salts of alkali-earth metals, salts of rare-earth
metals, clays and shaping additives. The amount of P-modified
zeolite which is contained in the catalyst ranges more
advantageously from 15 to 90 weight percent of the total catalyst,
preferably 20 to 70 weight percent of the catalyst. When adding
clay, the clay forms between about 10 and about 80 wt-% of the
dried catalyst product. The concentration of the salts of
alkali-earth metals and salts of rare-earth metals can be from 0.1
to 15 wt % of the catalyst on metal basis (Me). Advantageously the
molar ratio of (Al+Me)/P in the catalyst is in the range 0.5 to 3,
where the Me is alkali or rare-earth.
[0074] In mixing the P-zeolite with at least a component selected
among one or more binders, salts of alkali-earth metals, salts of
rare-earth metals and clays, the catalyst may be formulated into
pellets, extruded into other shapes, or formed into spheres or a
spray-dried powder. Typically, all the ingredients are mixed
together by a mixing process. By way of example in such a process,
the binder, for example silica, in the form of a gel is mixed with
the P-zeolite and the resultant mixture is extruded into the
desired shape, for example cylindic or multi-lobe bars. Spherical
shapes can be made in rotating granulators or by oil-drop
technique. Small spheres can further be made by spray-drying a
catalyst suspension.
[0075] Thereafter, the catalyst is calcined in air or an inert gas,
typically at a temperature of from 350 to 900.degree. C. for a
period of from 1 to 48 hours. Optionally the air or an inert gas
may contain steam in concentration from 10 to 90 vol %.
[0076] As regards steps c) and d*), the dried or calcined, shaped
catalyst particles may optionally be finished by contacting them
with water or an aqueous exchange solution of an ionic compound.
The aqueous exchange solution is characterized in that it is
effective for removing undesired metallic cations that may occupy
the ion exchange sites of the molecular sieve or/and introduction a
desirable metallic cations. The undesirable metallic cations are
Na, K, Fe, Zn, Cr, Mn, Ni, V, Mo, Co, Cu, Cd. These species can
originate from inorganic template material present in the molecular
sieve or, more commonly, stem from the inorganic oxide binder
source material (e.g. aluminum sol). In the processing service for
which the catalyst is designed these metal cations can promote side
reactions, slow the desired reaction rate, or otherwise complicate
the catalysis of the desired reaction. Some sources of the
inorganic oxide binder are essentially free of undesired metal
cations and therefore the dried particles produced using such
sources would not necessarily require contact with an exchange
solution. Water washing both before and after the finishing step
may be desired to flush the catalyst of undesired solids and/or
residual exchange solution.
[0077] In accordance with the present invention, at the step c) and
d*) the catalyst is treated with water for a period of time
advantageously from 0.5 to 48 hours, preferably for a period of
time from about 1 to 36 hours and most preferably from about 2 to
24 hours. The water was at a temperature between about 10.degree.
and 180.degree. C., preferably between about 15.degree. and
100.degree. C. and most preferably between about 20.degree. and
60.degree. C. Following the water treatment, the catalyst was dried
at about 60-350.degree. C. Optionally, the water can contain
ammonium or at least one of the metallic cations ions selected from
the group consisting of Li, Ag, Mg, Ca, Sr, Ba, Ce, Al, La, and
mixtures thereof which do not promote side reactions and stabilize
the zeolite against steam dealumination.
[0078] One skilled in the art will also appreciate that the olefins
made by the dehydration process of the present invention can be, by
way of example, polymerized. When the olefin is ethylene it can be,
by way of example,
[0079] polymerized to form polyethylenes,
[0080] dimerized to butene and then isomerised to isobutene, said
isobutene reacting with ethanol to produce ETBE,
[0081] dimerised to 1-butene, trimerised to 1-hexene or
tetramerised to 1-octene, said alpha-olefins comonomers are further
reacted with ethylene to produce polyethylene
[0082] dimerised to 1-butene, said 1-butene is isomerised to
2-butene and said 2-butene is further converted with ethylene by
metathesis reaction into propylene and said propylene can be
polymerised to polypropylene,
[0083] converted to ethylene oxide and glycol or
[0084] converted to vinyl chloride.
[0085] The present invention relates also to said polyethylenes,
polypropylene, propylene, butane, hexane, octene, isobutene, ETBE,
vinyl chloride, ethylene oxide and glycol.
EXAMPLES
[0086] The stainless-steel reactor tube has an internal diameter of
11 mm. 10 ml of catalyst, as pellets of 35-45 mesh, is loaded in
the tubular reactor. The void spaces before and after the catalyst
bed are filled with SiC granulates of 1 mm. The temperature profile
is monitored with the aid of a thermocouple well placed inside the
reactor. The reactor temperature is increased at a rate of
60.degree. C./h to 550.degree. C. under nitrogen, kept 1 hour at
550.degree. C. and then purged by nitrogen. The nitrogen is then
replaced by the feed at the indicated operating conditions.
[0087] Analysis of the products is performed by using an on-line
gas chromatography. [0088] Surfin 96 bio-ethanol [0089] In the
examples below, the bio-ethanol used is a Surfin 96 bio-ethanol,
meaning this ethanol produced by fermentation has been submitted to
different distillation and purification steps so as to get a high
purity bio-ethanol. [0090] The characteristics of the Surfin 96
bio-ethanol used in the examples below are gathered table 1.
TABLE-US-00001 [0090] TABLE 1 Main characteristics of Surfin96
bio-ethanol Surfin 96 Tot S ppm <0.2 Tot N ppm <0.5 Basic ppm
<1 volatile N Na mg/l 0.5 Ca mg/l <0.1 Mn mg/l <0.1 Fe
mg/l <0.5 Cu mg/l <0.2 Zn mg/l <0.1 Alcohol % vol @ 96.1
content 20.degree. C. Total acidity g/hl 0.8 acetic acid Esters
g/hl <0.1 Acetaldehyde/ g/hl <0.1 Acetal
Example 1
Catalyst A
[0091] The catalyst is a phosphorous modified zeolite (P-ZSM5),
prepared according to the following recipe. A sample of zeolite
ZSM-5 (Si/Al=13) in H-form was steamed at 550.degree. C. for 6 h in
100% H.sub.2O. Then, 1270 g of the steamed solid was subjected to a
contact with an aqueous solution containing 241.3 g of
H.sub.3PO.sub.4 (85% wt) for 2 h under reflux condition (4 ml/1 g
zeolite). Then 69.9 g of CaCO3 was introduced. Then the solution
was dried by evaporation for 3 days at 80.degree. C. 750 g of the
dried sample was extruded with 401.5 g of colloidal silica
(Bindzil, 34 wt % of SiO2, 200 ppm of Na) and 0.01 wt % of
extrusion additives. The extruded solid was dried at 110.degree. C.
for 16 h and calcinated at 600.degree. C. for 10 h. The catalyst
was then equilibrated 2 hours at 600.degree. C. under steam.
[0092] The sample is hereinafter identified as catalyst A.
[0093] Ethanol Dehydration Using Catalyst A
[0094] In this example, a mixture of 95% wt Surfin96 ethanol and 5%
wt water have been processed on catalyst A under the following
dehydration conditions: outlet pressure of 2 bara, a weight hour
space velocity referred to raw ethanol of 7 h.sup.-1, downflow,
inlet temperature of 400.degree. C. FIG. 1 shows the evolution of
the ethanol conversion (full points) and the ethylene yield (open
points) as a function of time of stream.
TABLE-US-00002 TABLE 2 Performances of the dehydration catalyst A
at 400.degree. C. under 2bara pressure using Surfin 96 bio-ethanol
diluted with 5% wt water, the WHSV (ethanol) = 7 h.sup.-1,
400.degree. C. EtOH/H2O (95/5)% wt FEED Surfin 96 P (bara) 2 T
(.degree. C.) 400 WHSV (H-1) 7 EtOH conversion (% wt CH2) 99.95 DEE
0.0 Acetaldyde 0.38 Yield on C-basis (% wt CH2) CH4 0.0 C2 0.21
C2.dbd. 95.6 C3.dbd. 0.9 C4+ olef 2.3 C4+ paraf 0.3 Aromatics 0.1
Unknown 0.13 Selectivity on C-basis (% wt CH2) CH4 0.0 C2 0.21
C2.dbd. 95.7 C3.dbd. 0.9 C4+ olef 2.3 C4+ paraf 0.3 Aromatics 0.1
Unknown 0.1 C2's purity (%) 99.79
Example 2
Catalyst B Synthesis
[0095] A sample of zeolite ZSM-5 (Si/Al=12) in H-form (contained
445 ppm of Na, below 25 ppm of K, 178 ppm of Fe, 17 ppm of Ca &
synthesized without template) was steamed at 550.degree. C. for 6 h
in 100% H.sub.2O at atmospheric pressure. Then, 600 g of the
steamed solid was subjected to a contact with an aqueous solution
of H.sub.3PO.sub.4 for 2 h under reflux condition (114 g of H3PO4,
4 ml/1 g zeolite) followed by introduction of 35 g of CaCO3 and
evaporation under stirring.
[0096] 720 g of the dried sample was extruded with 121 g of SiO2 in
form of Bindzil colloidal silica (34 wt % of SiO2, 200 ppm of Na)
and 2 wt % of extrusion additives. The extruded solid was dried at
110.degree. C. for 16 h, and steamed for 2 h at 600.degree. C. in
100% steam.
[0097] The sample is hereinafter identified as catalyst B.
[0098] Ethanol to Ethylene Using Catalyst B
[0099] In this example, a mixture of 95% wt Surfin96 ethanol and 5%
wt water have been processed on catalyst B under the following
dehydration conditions: outlet pressure of 2 bara, a weight hour
space velocity referred to raw ethanol of 7 h.sup.-1, downflow,
inlet temperature of 400.degree. C. FIG. 2 shows the evolution of
the ethanol conversion (rectangle) and the ethylene yield
(lozenges) as a function of time of stream.
TABLE-US-00003 TABLE 3 Performances of the dehydration catalyst B
at 360.degree. C. under 2bara pressure using Surfin 96 bio-ethanol
diluted with 5% wt water, the WHSV (ethanol) = 7 h.sup.-1. EtOH/H2O
FEED (95/5)% wt P (bara) 2 T (.degree. C.) 360 WHSV (H-1) 7 EtOH
conversion (% wt CH2) 99.91 DEE 0.0 Acetaldyde 0.19 Yield on
C-basis (% wt CH2) CH4 0.0 C2 0.21 C2.dbd. 95.5 C3.dbd. 0.9 C4+
olef 2.3 C4+ paraf 0.5 Aromatics 0.1 Unknown 0.18 Selectivity on
C-basis (% wt CH2) CH4 0.0 C2 0.21 C2.dbd. 95.6 C3.dbd. 0.9 C4+
olef 2.3 C4+ paraf 0.5 Aromatics 0.1 Unknown 0.2 C2's purity (%)
99.78
[0100] Butanol Dehydration Using Catalyst B:
[0101] In this example, an isobutanol/water mixture having the 95/5
wt % composition has been processed on the catalyst under 1.5 bara,
at temperatures of 280 and 300.degree. C., and with an isobutanol
space velocity of about 7 h.sup.-1.
[0102] In this set of operating conditions, isobutanol conversion
is almost complete, with a butenes selectivity of 90% wt or above,
and an iso-butene selectivity of about 66-67%. Thus, nearly 90% or
more butenes are produced, in which a significant amount are
skeletal isomerised into n-butenes. The heavies production is
limited to 10% or less.
TABLE-US-00004 TABLE 4 Performances of the dehydration catalyst B
at 280.degree. C. and 300.degree. under 1.5bara pressure using
Surfin 96 bio-ethanol diluted with 5% wt water, the WHSV (ethanol)
= 7 h.sup.-1. FEED: i-ButOH/H2O (95/5)% wt P (bara) 1.5 1.5 T
(.degree. C.) 300 280 WHSV (H-1) 7.4 7.4 Conversion (% wt CH2)
100.0 83.5 Oxygenates (% wt CH2) - Average Other alcohols 0.01 0.00
Other Oxygenates 0.03 0.08 Selectivity on C-basis (% wt CH2) -
Average Paraffins C1-C4 0.1 0.1 C2.dbd. 0.0 0.0 C3.dbd. 0.5 0.3
C4.dbd. 89.9 93.9 i-Butene 60.3 61.9 1-Butene 5.0 6.1 2-Butene 24.6
26.0 C5+ olef 4.8 2.7 C5+ paraf 1.9 1.1 Dienes 0.5 0.4 Aromatics
0.5 0.2 Unknown 1.6 1.1 C4.dbd. distribution - Average i-Butene
67.1 65.9 n-butenes 32.9 34.1 1-Butene 5.5 6.5 2-Butene 27.4
27.7
Example 3 (Comparative)
[0103] This example illustrates that the binder presence in the
catalyst interferes with introduction of phosphorous into zeolite.
The solid obtained by phosphotation of the extruded zeolite by wet
impregnation using the same proportion on zeolite basis of the
reagents as in case of powder (catalyst A, B), results in
non-selective catalyst for dehydration.
[0104] Catalyst C Synthesis (Comparative): [0105] 30 g of the
sample of ZSM-5 (Si/Al=12) in NH4-form (contained 445 ppm of Na,
below 25 ppm of K, 178 ppm of Fe, 17 ppm of Ca & synthesized
without template) was extruded with 20 wt % of SiO2 in form of
precipitated silica (contained 680 ppm of sodium) and 2 wt % of
extrusion additives. Then, the extruded sample was calcined at
600.degree. C. for 10 h and steamed at 550.degree. C. for 6 h in
100% of H2O. [0106] The 25 g of steamed solid was subjected to a
contact with an aqueous solution containing 3.8 g of H3PO4 (4.2 ml
H.sub.2O/1 g zeolite) under reflux conditions during 2 h. Then 1 g
of CaCO3 was introduced. The resulted solid was separated from the
solution, dried at 110.degree. C. for 16 h and equilibrated by
steaming at 600.degree. C. for 2 h. [0107] The sample is
hereinafter identified as sample C.
[0108] Ethanol to Ethylene Using Catalyst B & C for
Comparison
[0109] In these examples 1 ml of catalyst, as pellets of 35-45 mesh
and diluted in 9 ml of SiC 0.5 mm, is loaded in the tubular
reactor. A mixture of 25% wt Surfin96 ethanol and 75% wt water have
been processed on catalyst B & catalyst C in the same
dehydration conditions: outlet pressure of 2 bara, a weight hour
space velocity referred to raw ethanol of 7 h.sup.-1, downflow,
inlet temperature of 380.degree. C.
TABLE-US-00005 Comparison Catalyst B Catalyst C (Comparative) FEED
EtOH/H2O (25/75% P (bara) 2 2 T (.degree. C.) 380 380 WHSV (H-1) 7
7 EtOH conversion (% wt CH2) 99.91 99.97 Selectivity on C-basis (%
wt CH2) C2.dbd. 98.3 97.4 C3.dbd. 0.4 0.7 C4+ olefins 0.6 1.3 C4+
paraffins 0.1 0.3
The table above shows that the catalyst C produces more heavy
products (C3=, C4+) and lower ethylene selectivity than the
catalyst B.
* * * * *