U.S. patent application number 12/377036 was filed with the patent office on 2010-07-01 for alkaline earth metal compound-containing zeolite catalyst, preparation method and regeneration method thereof, and method for producing lower hydrocarbon.
This patent application is currently assigned to JCC CORPORATION. Invention is credited to Kazunori Honda, Chizu Inaki, Hirofumi Ito, Atsushi Okita, Koji Oyama.
Application Number | 20100168492 12/377036 |
Document ID | / |
Family ID | 39135920 |
Filed Date | 2010-07-01 |
United States Patent
Application |
20100168492 |
Kind Code |
A1 |
Inaki; Chizu ; et
al. |
July 1, 2010 |
ALKALINE EARTH METAL COMPOUND-CONTAINING ZEOLITE CATALYST,
PREPARATION METHOD AND REGENERATION METHOD THEREOF, AND METHOD FOR
PRODUCING LOWER HYDROCARBON
Abstract
An alkaline-earth metal compound-containing zeolite catalyst
composed of a composite material comprising at least a first
component, a second component, and a third component, wherein the
first component is composed of at least one of zeolites selected
from a group consisting of proton-type zeolites and ammonium type
zeolites, the second component is composed of at least one of
alkaline-earth metal compounds, and the third component is composed
of at least one selected from a group consisting of aluminum
oxides, aluminum hydroxides, silicon oxides, silicon hydroxides,
and clay minerals. The first component has a molar ratio of Si/Al
of 10 or more and 300 or less. Content of the second component
relative to the first component defined is 0.3 mass % or more and
less than 10 mass % as alkaline-earth metal. Content of the third
component relative to the first component is 15 mass % or more and
200 mass % or less.
Inventors: |
Inaki; Chizu; (Ishioka-shi,
JP) ; Ito; Hirofumi; (Mito-shi, JP) ; Honda;
Kazunori; (Ibaraki-ken, JP) ; Oyama; Koji;
(Yokohama-shi, JP) ; Okita; Atsushi; (Ibaraki-ken,
JP) |
Correspondence
Address: |
Leason Ellis LLP
81 Main Street, Suite 503
White Plains
NY
10601
US
|
Assignee: |
JCC CORPORATION
Tokyo
JP
|
Family ID: |
39135920 |
Appl. No.: |
12/377036 |
Filed: |
August 29, 2007 |
PCT Filed: |
August 29, 2007 |
PCT NO: |
PCT/JP2007/066766 |
371 Date: |
February 10, 2009 |
Current U.S.
Class: |
585/639 ; 502/38;
502/60; 502/64 |
Current CPC
Class: |
B01J 29/90 20130101;
C07C 2523/02 20130101; B01J 29/06 20130101; B01J 35/0006 20130101;
B01J 2229/42 20130101; B01J 23/02 20130101; B01J 37/0009 20130101;
B01J 38/16 20130101; C07C 2529/70 20130101; Y02P 20/52 20151101;
C07C 1/20 20130101; C07C 11/06 20130101; Y02P 20/584 20151101; C07C
1/20 20130101; B01J 29/40 20130101 |
Class at
Publication: |
585/639 ; 502/64;
502/60; 502/38 |
International
Class: |
B01J 29/04 20060101
B01J029/04; C07C 1/20 20060101 C07C001/20; B01J 38/12 20060101
B01J038/12 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 30, 2006 |
JP |
2006-234518 |
Sep 27, 2006 |
JP |
2006-262554 |
Sep 28, 2006 |
JP |
2006-266044 |
Claims
1. An alkaline-earth metal compound-containing zeolite catalyst
composed of a composite material comprising at least a first
component, a second component, and a third component, wherein the
first component is composed of at least one of zeolites selected
from a group consisting of proton-type zeolites and ammonium type
zeolites, the second component is composed of at least one of
alkaline-earth metal compounds, the third component is composed of
at least one selected from a group consisting of aluminum oxides,
aluminum hydroxides, silicon oxides, silicon hydroxides, and clay
minerals, the first component has a molar ratio of Si/Al of 10 or
more and 300 or less, content of the second component relative to
the first component defined is 0.3 mass % or more and less than 10
mass % as alkaline-earth metal, and content of the third component
relative to the first component is 15 mass % or more and 200 mass %
or less.
2. An alkaline-earth metal compound-containing zeolite catalyst
according to claim 1, wherein the first component is composed of at
least one of MFI-structure zeolites.
3. An alkaline-earth metal compound-containing zeolite catalyst
according to claim 1, wherein the second component is composed of
at least one of calcium compounds.
4. An alkaline-earth metal compound-containing zeolite catalyst
according to claim 2, wherein the second component is composed of
at least one of calcium compounds.
5. An alkaline-earth metal compound-containing zeolite catalyst
according to claim 1, having a characteristic such that where the
alkaline-earth metal compound-containing zeolite catalyst is
exposed for 48 hours to an atmosphere having steam partial pressure
of 0.35 MPa, and nitrogen partial pressure of 0.15 MPa, at
530.degree. C., the residual amount of tetrahedral aluminum in the
alkaline-earth metal compound-containing zeolite catalyst is not
smaller than five times of the residual amount of tetrahedral
aluminum in the proton-type zeolite consisting of the first
component which has been exposed for 48 hours to the same
atmosphere.
6. An alkaline-earth metal compound-containing zeolite catalyst
according to claim 1, which is used in a time of synthesizing lower
hydrocarbons from dimethyl ether and/or methanol.
7. A method for preparing an alkaline-earth metal
compound-containing zeolite catalyst, comprising: a mixing-kneading
step of adding polar solvent to a composition composed at least of
a first component, a second component, and a third component, and
kneading to form a mixture; and a drying-calcination step of drying
and calcining the mixture, wherein the first component is composed
of at least one of zeolites selected from a group consisting of
proton-type zeolites and ammonium type zeolites, the second
component is composed of at least one of alkaline-earth metal
compounds, the third component is composed of at least one selected
from a group consisting of aluminum oxides, aluminum hydroxides,
silicon oxides, silicon hydroxides, and clay minerals, the first
component has a molar ratio of Si/Al of 10 or more and 300 or less,
content of the second component relative to the first component is
0.3 mass % or more and less than 10 mass % as alkaline-earth metal,
and content of the third component relative to the first component
is 15 mass % or more and 200 mass % or less.
8. A method for preparing an alkaline-earth metal
compound-containing zeolite catalyst, further comprising a steam
treatment step where a composite material obtained by the
drying-calcination step is made contact to steam or reaction
atmosphere that generates steam.
9. A method for preparing an alkaline-earth metal
compound-containing zeolite catalyst according to claim 7, wherein
the first component is composed of at least one of MFI-structure
zeolites.
10. A method for preparing an alkaline-earth metal
compound-containing zeolite catalyst according to claim 7, wherein
the second component is composed of at least one of calcium
compounds.
11. A method for preparing an alkaline-earth metal
compound-containing zeolite catalyst according to claim 9, wherein
the second component is composed of at least one of calcium
compounds.
12. A method of producing lower hydrocarbons by synthesizing lower
hydrocarbons from dimethyl ether and/or methanol, using the
alkaline-earth metal compound-containing zeolite catalyst according
to claim 6, wherein yield of propylene is 40 mass % or more, yield
of methane is less than 1.0 mass %, and yield of carbon monoxide is
0.5 mass % or less.
13. A method for regenerating an alkaline-earth metal
compound-containing zeolite catalyst used for synthesizing lower
hydrocarbons from dimethyl ether and/or methanol, comprising a step
of calcining the alkaline-earth metal compound-containing zeolite
catalyst according to claim 6 in a flow containing oxygen and
steam.
14. A method for regenerating an alkaline-earth metal
compound-containing zeolite catalyst according to claim 13, wherein
a temperature for calcining the alkaline-earth metal
compound-containing zeolite catalyst is controlled in the range
from 400.degree. C. to 700.degree. C.
15. An alkaline-earth metal compound-containing zeolite catalyst
according to claim 2, having a characteristic such that where the
alkaline-earth metal compound-containing zeolite catalyst is
exposed for 48 hours to an atmosphere having steam partial pressure
of 0.35 MPa, and nitrogen partial pressure of 0.15 MPa, at
530.degree. C., the residual amount of tetrahedral aluminum in the
alkaline-earth metal compound-containing zeolite catalyst is not
smaller than five times of the residual amount of tetrahedral
aluminum in the proton-type zeolite consisting of the first
component which has been exposed for 48 hours to the same
atmosphere.
16. An alkaline-earth metal compound-containing zeolite catalyst
according to claim 3, having a characteristic such that where the
alkaline-earth metal compound-containing zeolite catalyst is
exposed for 48 hours to an atmosphere having steam partial pressure
of 0.35 MPa, and nitrogen partial pressure of 0.15 MPa, at
530.degree. C., the residual amount of tetrahedral aluminum in the
alkaline-earth metal compound-containing zeolite catalyst is not
smaller than five times of the residual amount of tetrahedral
aluminum in the proton-type zeolite consisting of the first
component which has been exposed for 48 hours to the same
atmosphere.
17. An alkaline-earth metal compound-containing zeolite catalyst
according to claim 4, having a characteristic such that where the
alkaline-earth metal compound-containing zeolite catalyst is
exposed for 48 hours to an atmosphere having steam partial pressure
of 0.35 MPa, and nitrogen partial pressure of 0.15 MPa, at
530.degree. C., the residual amount of tetrahedral aluminum in the
alkaline-earth metal compound-containing zeolite catalyst is not
smaller than five times of the residual amount of tetrahedral
aluminum in the proton-type zeolite consisting of the first
component which has been exposed for 48 hours to the same
atmosphere.
18. An alkaline-earth metal compound-containing zeolite catalyst
according to claim 2, which is used in a time of synthesizing lower
hydrocarbons from dimethyl ether and/or methanol.
19. An alkaline-earth metal compound-containing zeolite catalyst
according to claim 3, which is used in a time of synthesizing lower
hydrocarbons from dimethyl ether and/or methanol.
20. An alkaline-earth metal compound-containing zeolite catalyst
according to claim 4, which is used in a time of synthesizing lower
hydrocarbons from dimethyl ether and/or methanol.
21. A method for preparing an alkaline-earth metal
compound-containing zeolite catalyst according to claim 8, wherein
the first component is composed of at least one of MFI-structure
zeolites.
22. A method for preparing an alkaline-earth metal
compound-containing zeolite catalyst according to claim 8, wherein
the second component is composed of at least one of calcium
compounds.
Description
TECHNICAL FIELD
[0001] The present invention relates to an alkaline-earth metal
compound-containing zeolite catalyst (zeolite-based catalyst that
contains alkaline-earth metal compound) which is used in the
synthetic process of lower hydrocarbons by dehydration condensation
reaction from dimethyl ether and/or methanol, and also relates to a
method for preparing the zeolite catalyst. Specifically, the
present invention relates to an alkaline-earth metal
compound-containing zeolite catalyst in which elimination of
tetrahedral aluminum from zeolite framework is not likely to occur
and exhibits slow formation rate of carbonaceous deposits during
reaction, and relates to a method for producing the zeolite
catalyst. The present invention also relates to a method for
producing a lower hydrocarbons utilizing the alkaline-earth metal
compound-containing zeolite catalyst. The present invention also
relates to a method for regenerating the alkaline-earth metal
compound-containing zeolite catalyst that is used in the synthetic
process of lower hydrocarbons by dehydration condensation reaction
from dimethyl ether and/or methanol.
[0002] Priority is claimed on Japanese Patent Application No.
2006-234518, filed Aug. 30, 2006, Japanese Patent Application No.
2006-262554, filed Sep. 27, 2006, and Japanese Patent Application,
No. 2006-266044, filed Sep. 28, 2006, the content of which is
incorporated herein by reference.
BACKGROUND ART
[0003] Zeolite catalysts are used in various processes such as DTO
reaction/MTO reaction for synthesizing lower hydrocarbons from
dimethyl ether (hereafter referred to as DME) and/or methanol, MTG
reaction for synthesizing gasoline from methanol, fluid catalytic
cracking (FCC) or the like.
[0004] In these processes, deactivation of zeolite catalysts may
occur. For example, the following is the main reason for
deactivating zeolite catalysts. Where the zeolite catalyst is
exposed to the reaction atmosphere containing steam, elimination of
aluminum from the zeolite framework (dealumination) may occur. In
addition, carbonaceous deposits are formed on the zeolite catalysts
during the reaction.
[0005] Reduction of catalytic activity caused by the formation of
carbonaceous deposits on the catalyst may be solved by providing a
flow containing oxygen to the catalyst and burning the carbonaceous
deposits on the catalyst. On the other hand, as a countermeasure
for reduction of catalytic activity caused by the elimination of
aluminum from the zeolite framework, a method is proposed for
inserting aluminum into the framework by treating the dealuminated
zeolite in particular conditions.
[0006] As methods for regenerating a dealuminated zeolite, a method
for regenerating the zeolite using aluminum chloride and acid (for
example, Patent Reference 1: Japanese Unexamined Patent
Application, First Publication No. S59-136138), and a method for
regenerating the zeolite using steam and ammonia are disclosed (for
example, Patent Reference 2: Japanese Unexamined Patent
Application, First Publication No. S60-257838).
[0007] In addition, a method for inserting aluminum into a
high-silica zeolite by compounding a high-silica zeolite with
alumina (aluminum oxide) and treating the compounded material with
steam is known (for example, Patent Reference 3: Japanese Examined
Patent Application, Second Publication No. H3-63430, Patent
Reference 4: U.S. Pat. No. 4,559,314, Patent Reference 5: U.S. Pat.
No. 4,784,747, Patent Reference 6: Japanese Patent, No. 2908959,
Non Patent Reference 1: J. Catal., 93, 471 (1985), Non Patent
Reference 2: J. Chem. Soc. Faraday Trans. 1, 81, 2215 (1985)).
[0008] However, the method for regenerating the dealuminated
zeolite included a disadvantage in the applicability to industrial
processes because of requirements for specific reagents or gas for
the regeneration.
[0009] In addition, although the above-described method to compound
the high-silica zeolite with alumina and to treat the compounded
material with steam was examined on the zeolite containing a small
amount of aluminum, for example a zeolite having a molar ratio of
Si/Al>1200. The method was not examined on the zeolite having a
molar ratio of Si/Al from several tens to ca. 300, which was
frequently used in industrial processes.
[0010] On the other hand, it is known that the formation rate of
carbonaceous deposits on the zeolite catalyst can be decreased by a
proper steam treatment. In a disclosed method, catalytic lifetime
for synthesizing hydrocarbons from methanol is increased by
exposing MFI-structure zeolite catalyst to steam thereby
controlling acid sites (active sites) of the zeolite (e.g., Patent
Reference 7: U.S. Pat. No. 4,429,176, Patent Reference 8: U.S. Pat.
No. 4,663,942, Patent Reference 9: U.S. Pat. No. 4,579,993). In
addition, it is found that lifetime of an alumina-containing
zeolite catalyst is prolonged by exposing the alumina-containing
zeolite catalyst to steam thereby decreasing the coking rate of the
catalyst (e.g., Patent Reference 10: U.S. Pat. No. 4,456,780).
However, it has been unknown how the addition of alumina change the
steam resistance of zeolite catalysts. In addition, there is no
report treating a catalyst containing zeolite, alumina, and
alkaline-earth metal compound with steam.
[0011] In DTO reaction/MTO reaction, it is disclosed that by using
a proton-type MFI-structure zeolite impregnated with alkaline-earth
metal compound, selectivity to lower olefins is increased,
formations of paraffins and aromatic hydrocarbons are depressed,
and formation of carbonaceous deposits is depressed, thereby
prolonging lifetime of the catalyst (e.g., Patent Reference 11:
Japanese Unexamined Patent Application, First Publication, No.
S60-126233). However, in Patent Reference 11, it was not examined
if lifetime of the zeolite catalyst modified with alkaline-earth
metal compound was changed (or is not changed) by repeating
regeneration of the catalyst after performing DTO reaction/MTO
reaction. In addition, steam resistance of the catalyst is not
described in Patent Reference 11.
[0012] As a representative example of catalyst used for DTO
reaction/MTO reaction, MFI-structure zeolite catalysts and SAPO-34
catalysts may be used.
[0013] In the DTO reaction/MTO reaction, activity of the catalyst
is decreased by formation of carbonaceous deposits on the catalyst.
Therefore, it is necessary to periodically introduce an
oxygen-containing flow to the catalyst so as to burn the
carbonaceous deposits on the catalyst, thereby regenerating the
catalytic activity.
[0014] The combustion reaction to burn the carbonaceous deposits on
the catalyst is an exothermal reaction. So as to prevent changing
the catalyst such as collapse of crystal structure, and for a
stable operation of apparatus used in the process, it is preferable
to inhibit large increase of temperature. Therefore, in the
above-described combustion reaction, so as to depress oxygen
concentration to a lower level, the air introduced to the catalyst
must be diluted by inert gas such as steam and nitrogen.
[0015] However, steam promote the elimination of aluminum from the
zeolite catalyst to lead decreasing catalyst lifetime. Therefore,
there is a method for using nitrogen as the dilution gas to keep
the steam concentration at low level (e.g., U.S. Published Patent
Application No. 2005/0085375)
[0016] It is difficult to apply the above-described method of
regenerating dealuminated zeolite in industrial processes. In
addition, the method includes a problem that an extra step is
needed for inserting aluminum into the dealuminated zeolite.
Therefore, in order to improve the lifetime of zeolite catalyst, it
is necessary to produce a zeolite catalyst in which the framework
aluminum is not likely to be eliminated.
[0017] On the other hand, when nitrogen gas is used to dilute the
oxygen concentration in the regeneration atmosphere, a cryogenic
air separator for producing the nitrogen gas is required, thereby
increasing construction cost of a plant.
[0018] Based on the above described consideration, an object of the
present invention is to provide an alkaline-earth metal
compound-containing zeolite catalyst, in which the elimination of
tetrahedral aluminum from the zeolite framework is not likely to
occur, and a simple inexpensive method for preparing the
above-described zeolite catalyst. Another object of the present
invention is to provide a method for regenerating alkaline-earth
metal compound-containing zeolite catalyst, by which method,
catalytic activity of the alkaline-earth metal compound-containing
zeolite catalyst is regenerated through a simple process, and
lifetime of the catalyst is improved.
DISCLOSURE OF INVENTION
[0019] An alkaline-earth metal compound-containing zeolite catalyst
according to the present invention is composed of a composite
material comprising at least a first component, a second component,
and a third component, wherein the first component is composed of
at least one of zeolites selected from a group consisting of
proton-type zeolites and ammonium type zeolites, the second
component is composed of at least one of alkaline-earth metal
compounds, and the third component is composed of at least one
selected from a group consisting of aluminum oxides, aluminum
hydroxides, silicon oxides, silicon hydroxides, and clay minerals.
The first component has a molar ratio of Si/Al of 10 or more and
300 or less. Content of the second component relative to the first
component is 0.3 mass % or more and less than 10 mass % as
alkaline-earth metal. Content of the third component relative to
the first component is 15 mass % or more and 200 mass % or
less.
[0020] It is preferable that the alkaline-earth metal
compound-containing zeolite catalyst according to the present
invention comprises the above-described first component composed of
at least one of MFI-structure zeolites.
[0021] It is preferable that the second component of the
alkaline-earth metal compound-containing zeolite catalyst according
to the present invention is composed at least one of calcium
compounds.
[0022] An alkaline-earth metal compound-containing zeolite catalyst
according to the present invention may has a characteristic such
that where an alkaline-earth metal compound-containing zeolite
catalyst according to the present invention is exposed for 48 hours
to an atmosphere having steam partial pressure of 0.35 MPa and
nitrogen partial pressure of 0.15 MPa at 530.degree. C., and the
residual amount of tetrahedral aluminum in zeolite framework per
unit mass of zeolite is measured, the residual amount of
tetrahedral aluminum in the zeolite catalyst of the present
invention is not smaller than five times of the residual amount of
tetrahedral aluminum in the proton-type zeolite consisting of the
first component which has been exposed for 48 hours to the above
described atmosphere.
[0023] An alkaline-earth metal compound-containing zeolite catalyst
according to the present invention may be used for synthesizing
lower hydrocarbons from DME and/or methanol.
[0024] A method for preparing an alkaline-earth metal
compound-containing zeolite catalyst according to the present
invention comprises: a mixing-kneading step of adding polar solvent
to a composition composed at least of a first component, a second
component, and a third component, and kneading to form a mixture;
and a drying-calcination step of drying and calcining the mixture,
where the first component is composed of at least one of zeolites
selected from a group consisting of proton-type zeolites and
ammonium type zeolites, the second component is composed of at
least one of alkaline-earth metal compounds, and the third
component is composed of at least one selected from a group
consisting of aluminum oxides, aluminum hydroxides, silicon oxides,
silicon hydroxides, and clay minerals. The first component has a
molar ratio of Si/Al of 10 or more and 300 or less. Content of the
second component relative to the first component is 0.3 mass % or
more and less than 10 mass % as alkaline-earth metal. Content of
the third component relative to the first component is 15 mass % or
more and 200 mass % or less.
[0025] It is preferable that a method for preparing an
alkaline-earth metal compound-containing zeolite catalyst according
to the present invention further comprises a steam treatment step
where the composite material obtained by the above-described
drying-calcination step is made contact to steam or reaction
atmosphere that generates steam.
[0026] In a method for preparing an alkaline-earth metal
compound-containing zeolite catalyst according to the present
invention, the above-described first component is preferably
composed of at least one of MFI-structure zeolites.
[0027] In a method for preparing an alkaline-earth metal
compound-containing zeolite catalyst according to the present
invention, it is preferable that the second component is composed
of at least one of calcium compounds.
[0028] A method of producing lower hydrocarbons according to the
present invention is a method for synthesizing lower hydrocarbons
from DME and/or methanol, where the alkaline-earth metal
compound-containing zeolite catalyst is used in the synthesis, and
yield of propylene is 40 mass % or more, yield of methane is less
than 1.0 mass %, and yield of carbon monoxide is 0.5 mass % or
less.
[0029] A method for regenerating alkaline-earth metal
compound-containing zeolite catalyst according to the invention is
a method for regenerating alkaline-earth metal compound-containing
zeolite catalyst used for synthesizing lower hydrocarbons from DME
and/or methanol. The method includes a step of calcining an
alkaline-earth metal compound-containing zeolite catalyst of the
present invention in a flow containing oxygen and steam.
[0030] It is preferable that the above-described calcination of the
alkaline-earth metal compound-containing zeolite catalyst is
performed at 400.degree. C. or more and 700.degree. C. or less.
EFFECT OF THE INVENTION
[0031] An alkaline-earth metal compound-containing zeolite catalyst
according to the present invention is composed of a composite
material comprising at least a first component, a second component,
and a third component, wherein the first component is composed of
at least one of zeolites selected from a group consisting of
proton-type zeolites and ammonium type zeolites, the second
component is composed of at least one of alkaline-earth metal
compounds, and the third component is composed of at least one
selected from a group consisting of aluminum oxides, aluminum
hydroxides, silicon oxides, silicon hydroxides, and clay minerals.
The first component has a molar ratio of Si/Al of 10 or more and
300 or less, content of the second component relative to the first
component is 0.3 mass % or more and less than 10 mass % as
alkaline-earth metal, and content of the third component relative
to the first component is 15 mass % or more and 200 mass % or less.
The catalyst of this constitution has a long catalytic lifetime
since the elimination of aluminum from the zeolite framework is
inhibited by the presence of the second component and the third
component. Therefore, by the improvement of overall catalytic
lifetime, loading weight of catalyst and frequency of recharging
the catalyst are reduced, and it is possible to reduce the
equipment cost and the operation cost.
[0032] A method for preparing an alkaline-earth metal
compound-containing zeolite catalyst according to the present
invention comprises: a mixing-kneading step of adding polar solvent
to a composition composed at least of a first component, a second
component, and a third component, and kneading to form a mixture;
and a drying-calcination step of drying and calcining the mixture,
where the first component is composed of at least one of zeolites
selected from a group consisting of proton-type zeolites and
ammonium type zeolites, the second component is composed of at
least one of alkaline-earth metal compounds, and the third
component is composed of at least one selected from a group
consisting of aluminum oxides, aluminum hydroxides, silicon oxides,
silicon hydroxides, and clay minerals, the first component has a
molar ratio of Si/Al of 10 or more and 300 or less, content of the
second component relative to the first component is 0.3 mass % or
more and less than 10 mass % as alkaline-earth metal, and content
of the third component relative to the first component is 15 mass %
or more and 200 mass % or less.
[0033] In this preparation method, an alkaline-earth metal
compound-containing zeolite catalyst can be obtained easily and at
low cost by using generally available and inexpensive proton-type
MFI-structure zeolite or ammonium type MFI-structure zeolite,
mixing with the second component and the third component, kneading,
drying, and calcining the mixture of the zeolite. This catalyst is
not likely to occur elimination of tetrahedral aluminum from the
zeolite framework, and has excellent steam resistance and a long
catalytic lifetime.
[0034] Since the alkaline-earth metal compound-containing zeolite
catalyst is used in the method of producing lower hydrocarbons
according to the present invention, lower hydrocarbons can be
obtained at a high yield. In addition, by the improvement of the
catalytic lifetime, frequency of regeneration is decreased.
Therefore, productivity of lower hydrocarbons is increased and
production cost can be reduced.
[0035] A method for regenerating alkaline-earth metal
compound-containing zeolite catalyst according to the present
invention is a method for regenerating alkaline-earth metal
compound-containing zeolite catalyst used for synthesizing lower
hydrocarbons from DME and/or methanol. In this method, the
alkaline-earth metal compound-containing zeolite catalyst of the
present invention is calcined in a flow containing oxygen and
steam, thereby improving the catalytic lifetime. Therefore,
frequency of regeneration of catalyst is decreased. As a result, it
is possible to reduce the cost for synthesizing lower hydrocarbons
from DME and/or methanol. In addition, since steam can be used as a
dilution gas in the time of regenerating the catalyst, it is not
necessary to provide extra facilities such as a cryogenic air
separator or the like.
BRIEF EXPLANATION FOR DRAWINGS
[0036] FIG. 1 is a graph showing relative catalytic lifetime of
catalysts A to F prepared in Experimental Examples 1-7 versus
extent of steam treatment.
BEST MODE FOR CARRYING OUT THE INVENTION
First Embodiment
[0037] An embodiment of an alkaline-earth metal compound-containing
zeolite catalyst according to the present invention, a preparation
method for same, and a method for producing lower hydrocarbons
utilizing the alkaline-earth metal compound-containing zeolite
catalyst is explained below.
[0038] It should be understood that this embodiment is an example
to provide better understanding of the scope of the invention and
the present invention is not limited to the description of this
embodiment.
[0039] [Alkaline-Earth Metal Compound-Containing Zeolite
Catalyst]
[0040] An alkaline-earth metal compound-containing zeolite catalyst
according to the present invention is composed of a composite
material comprising at least a first component, a second component,
and a third component, wherein the first component is composed of
at least one of zeolites selected from a group consisting of
proton-type zeolites and ammonium type zeolites, the second
component is composed of at least one of alkaline-earth metal
compounds, and the third component is composed of at least one
selected from a group consisting of aluminum oxides, aluminum
hydroxides, silicon oxides, silicon hydroxides, and clay minerals.
The first component has a molar ratio of Si/Al of 10 or more and
300 or less. Content of the second component relative to the first
component is 0.3 mass % or more and less than 10 mass % as
alkaline-earth metal. Content of the third component relative to
the first component is 15 mass % or more and 200 mass % or
less.
[0041] It is preferable that the alkaline-earth metal
compound-containing zeolite catalyst according to the present
invention comprises the above-described first component composed of
at least one of MFI-structure zeolites, where "MFI-structure" is a
name of a framework structure defined in the International Zeolite
Association.
[0042] In the alkaline-earth metal compound-containing zeolite
catalyst of the present invention, the proton-type zeolite or
ammonium-type zeolite that constitutes the first component has a
molar ratio of Si/Al of 10 or more and 300 or less.
[0043] Where the molar ratio of Si/Al is less than 10, too many
acid sites exist on the catalyst surface and formation of
carbonaceous deposits on the catalyst is enhanced, thereby
shortening catalytic lifetime. On the other hand, if the molar
ratio of Si/Al exceeds 300, effective acid sites are decreased
thereby reducing catalytic activity.
[0044] It is preferable that the content of the second component as
alkaline-earth metal relative to the first component be 0.3 mass %
or more and less than 10 mass %.
[0045] Where the content of the second component as alkaline-earth
metal relative to the first component is less than 0.3 mass %,
acidic properties of the catalyst and dealumination cannot be
controlled sufficiently. On the other hand, where the content of
the second component as alkaline-earth metal relative to the first
component is more than 10 mass %, it is not preferable because side
reactions are caused by excessive amount of the alkaline-earth
metal compound (mainly composed of oxide and carbonate).
[0046] The content of the third component relative to the content
of the first component is preferably 15 mass % or more and 200 mass
% or less.
[0047] Where the content of the third component relative to the
first component is less than 15 mass %, there occurs problems such
as decrease in physical strength of the obtained catalyst resulting
in powderization of the catalyst during using the catalyst. On the
other hand, where the content of the third component relative to
the first component exceeds 200 mass %, proportion of the first
component active to the reaction is decreased, and catalytic
performance is deteriorated.
[0048] In the alkaline-earth metal compound-containing zeolite
catalyst of the present invention, it is preferable that the first
component constituting the composite material is composed of at
least one of zeolites selected from a group consisting of
proton-type zeolites and ammonium type zeolites that have a
MFI-structure. By using generally available and inexpensive
proton-type zeolite or ammonium-type zeolite, it is possible to
easily prepare an alkaline-earth metal-containing catalyst at low
cost according to the present invention that has excellent steam
resistance.
[0049] The alkaline-earth metal compound of the second component
may be selected from magnesium carbonate (MgCO.sub.3), magnesium
hydroxide (Mg(OH).sub.2), magnesium oxide (MgO), magnesium acetate
((CH.sub.3COO).sub.2Mg), magnesium nitrate (Mg(NO.sub.3).sub.2),
magnesium aluminate (MgAl.sub.2O.sub.4), magnesium orthosilicate
(Mg.sub.2SiO.sub.4), calcium carbonate (CaCO.sub.3), calcium
hydroxide (Ca(OH).sub.2), calcium oxide (CaO), calcium acetate
((CH.sub.3COO).sub.2Ca), calcium nitrate (Ca(NO.sub.3).sub.2),
calcium aluminate (CaAl.sub.2O.sub.4), calcium orthosilicate
(Ca.sub.2SiO.sub.4), strontium carbonate (SrCO.sub.3), strontium
hydroxide (Sr(OH).sub.2), strontium oxide (SrO), strontium acetate
((CH.sub.3COO).sub.2Sr), strontium nitrate (Sr(NO.sub.3).sub.2),
strontium aluminate (SrAl.sub.2O.sub.4), strontium silicate, barium
carbonate (BaCO.sub.3), barium hydroxide (Ba(OH).sub.2), barium
oxide (BaO), barium acetate ((CH.sub.3COO).sub.2Ba), barium nitrate
(Ba(NO.sub.3).sub.2), barium aluminate (BaAl.sub.2O.sub.4), barium
silicate or the like.
[0050] The third component is composed of at least one selected
from a group consisting of aluminum oxides, aluminum hydroxides,
silicon oxides, silicon hydroxides, and clay minerals.
[0051] For example, .gamma.-alumina (Al.sub.2O.sub.3) or the like
may be applied as the aluminum oxides.
[0052] As the aluminum hydroxides, boehmite (AlO(OH)), aluminum
hydroxide (Al(OH).sub.3), alumina sol or the like may be used.
[0053] Silicon dioxide (SiO.sub.2) may be used as the silicon
oxides.
[0054] Silicon hydroxides may have a form of orthosilicate
(H.sub.4SiO.sub.4), metasilicate (H.sub.2SiO.sub.3) or the
like.
[0055] Kaolin, bentonite or the like may be used as the clay
minerals.
[0056] Where necessary, additives composed of graphite, cellulose
or the like may be added to the alkaline-earth metal
compound-containing zeolite catalyst of the present invention.
[0057] Where an alkaline-earth metal compound-containing zeolite
catalyst of the above-described constitution is exposed for 48
hours to an atmosphere having steam partial pressure of 0.35 MPa
and nitrogen partial pressure of 0.15 MPa at 530.degree. C., and a
proton-type zeolite consisting only of the above-described first
component is exposed to the same atmosphere under the same
condition, after the exposure, the residual amount of tetrahedral
aluminum in the zeolite framework per unit mass of zeolite in the
alkaline-earth metal compound-containing catalyst is preferably not
smaller than 5 times, more preferably not smaller than 10 times, of
the residual amount of tetrahedral aluminum in the zeolite
framework per unit mass of zeolite in the proton-type zeolite
consisting of the first component.
[0058] Where the residual amount of tetrahedral aluminum in the
zeolite framework per unit mass of zeolite in the alkaline-earth
metal compound-containing catalyst after exposure to the
above-described conditions is not smaller than 5 times of the
residual amount of tetrahedral aluminum in the zeolite framework
per unit mass of zeolite in the proton-type zeolite consisting of
the first component treated with steam under the same condition, it
is possible to reduce the degree of deterioration of catalytic
activity caused by exposure to steam in the reaction atmosphere or
in the regeneration atmosphere. Therefore, it is possible to
increase the number of times of regeneration of the catalyst, and
decrease the frequency for recharging the catalyst.
[0059] An alkaline-earth metal compound-containing zeolite catalyst
according to the present invention is composed of a composite
material comprising at least a first component, a second component,
and a third component, wherein the first component is composed of
at least one of zeolites selected from a group consisting of
proton-type zeolites and ammonium type zeolites, the second
component is composed of at least one of alkaline-earth metal
compounds, and the third component is composed of at least one
selected from a group consisting of aluminum oxides, aluminum
hydroxides, silicon oxides, silicon hydroxides, and clay minerals,
where the first component has a molar ratio of Si/Al of 10 or more
and 300 or less, content of the second component relative to the
first component is 0.3 mass % or more and less than 10 mass % as
alkaline-earth metal, and content of the third component relative
to the first component is 15 mass % or more and 200 mass % or less.
Since both the second component and the third component inhibit the
elimination of aluminum from zeolite framework, the zeolite
catalyst of the above-described constitution has a long catalytic
lifetime. Therefore, by the improvement of the overall catalytic
lifetime, loading weight of catalyst and frequency of recharging
the catalyst are reduced, and it is possible to reduce the
equipment cost and the operation cost of the reaction system.
[Method of Preparing The Alkaline-Earth Metal Compound-Containing
Zeolite Catalyst]
[0060] A method of preparing an alkaline-earth metal
compound-containing zeolite catalyst of the present invention is
explained below.
Mixing-Kneading Step
[0061] Firstly, by using mortar, milling machine, kneader or the
like, a composition at least containing a first component, a second
component, and a third component is mixed with a polar solution and
kneaded, to prepare a mixture composed of at least the first
component, the second component, the third component, and polar
solution.
[0062] In this mixing-kneading step, at least one of zeolites
having a Si/Al molar ratio of 10 or more and 300 or less, selected
from a group consisting of proton-type zeolites and ammonium type
zeolites is used as the first component.
[0063] At least one of alkaline-earth metal compounds is used as
the second component.
[0064] As the third component, at least one selected from a group
consisting of aluminum oxides, aluminum hydroxides, silicon oxides,
silicon hydroxides, and clay minerals is used.
[0065] In the mixing-kneading step, content of the second component
relative to the first component is controlled to be 0.3 mass % or
more and less than 10 mass %.
[0066] Content of the third component relative to the first
component is controlled to be 15 mass % or more and 200 mass % or
less.
[0067] In addition, relative to the amount of the composition at
least containing the first component, the second component, and the
third component, added amount of polar solution is controlled to be
10 mass % or more and 150 mass % or less.
[0068] As the polar solution, water is most preferably used. In
addition, it is possible to use organic polar solution including
alcohol group solution such as ethanol and propanol, ether group
solution such as diethyl ether and tetrahydrofuran, ester group
solution, amid group solution, sulfoxide group solution.
[0069] In addition, in the time of producing a composite material,
in addition to the polar solution, it is also possible to add a
material which is to be removed in the time of drying and
calcining. Such material may include organic acid such as acetic
acid, aqueous ammonia, graphite, cellulose group or the like.
Molding Step
[0070] Next, the mixture obtained in the mixing-kneading step is
formed into a shaped catalyst, for example, by extrusion molding
using an extruder, or by spheronization molding using a spheronizer
(marumerizer).
Drying-Calcination Step
[0071] Next, the shaped catalyst obtained in the molding step is
dried by a drying machine, and is subjected to calcination using a
furnace such as muffle furnace, tunnel furnace or the like, thereby
preparing a composite material. Thus, the alkaline-earth metal
compound-containing zeolite catalyst according to the invention can
be obtained.
[0072] In the above-described drying-calcination step, it is
preferable to perform the drying of the shaped catalyst under
conditions at 80.degree. C. or more and 150.degree. C. or less for
a duration of 0.5 hours or more and 30 hours or less.
[0073] In the drying-calcination step, it is preferable that the
shaped catalyst after drying is subjected to calcination at
350.degree. C. or more and 750.degree. C. or less for a duration of
not shorter than 1 hour and not longer than 50 hours.
[0074] A method for preparing an alkaline-earth metal
compound-containing zeolite catalyst according to the present
invention comprises: mixing-kneading step of adding polar solvent
to a composition composed at least of a first component, a second
component, and a third component, and kneading to form a mixture;
and drying-calcination step of drying and calcining the mixture to
prepare a composite material, where the first component is composed
of at least one of zeolites selected from a group consisting of
proton-type zeolites and ammonium type zeolites, the second
component is composed of at least one of alkaline-earth metal
compounds, and the third component is composed of at least one
selected from a group consisting of aluminum oxides, aluminum
hydroxides, silicon oxides, silicon hydroxides, and clay minerals.
The first component has a molar ratio of Si/Al of 10 or more and
300 or less, content of the second component relative to the first
component defined is 0.3 mass % or more and less than 10 mass % as
alkaline-earth metal, and content of the third component relative
to the first component is 15 mass % or more and 200 mass % or
less.
[0075] In this preparation method, by constituting the first
component using generally available proton-type zeolite and/or
ammonium-type zeolite, and by mixing and kneading the first
component with the second component and the third component to form
a mixture, and drying and calcining the mixture, it is possible to
produce simply and inexpensively an alkaline-earth metal
compound-containing zeolite catalyst having excellent steam
resistance, and long catalytic lifetime.
[Method of Producing Lower Hydrocarbons]
[0076] In the following, a method of producing lower hydrocarbons
from DME and/or methanol is described as an embodiment utilizing
the alkaline-earth metal compound-containing zeolite catalyst of
the present invention.
Steam Treatment Step
[0077] The alkaline-earth metal compound-containing zeolite
catalyst consisting of the composite material obtained in the
above-described drying-calcination step may be subjected to a steam
treatment step where the catalyst is made contact to steam; or air
and/or inert gas (e.g., nitrogen and carbon dioxide) that contains
steam in an amount of not less than 10 vol %. Alternatively, the
catalyst may be made contact to reaction atmosphere that generates
steam. In the steam treatment, it is allowable to use conditions in
which steam partially exist as liquid water. In addition, it is
possible to perform the steam treatment step simultaneously with
the drying-calcination step.
[0078] The above described reaction that generates steam refers to
the reaction in which dehydration of reactants occurs on the
catalyst surface, thereby generating steam. DTO reaction/MTO
reaction and dehydration of alcohol are examples of the
reaction.
[0079] In the steam treatment step, it is preferable that the
duration for making the composite material contact to steam or the
reaction atmosphere generating steam is not shorter than 1 hour and
not longer than 50 hours.
[0080] So as to synthesize lower hydrocarbons from one or both of
DME and methanol utilizing the alkaline-earth metal
compound-containing zeolite catalyst treated with steam, DME and/or
methanol is supplied as a gas, and the gas is made contact with the
alkaline-earth metal compound-containing zeolite catalyst. As the
method for making the catalyst to contact with the gas, fixed bed
reactor or fluid bed reactor may be applied.
[0081] In the method of producing lower hydrocarbons, the synthetic
reaction of lower hydrocarbons from DME and/or methanol may be
performed using a wide range of temperature/pressure
conditions.
[0082] Preferably, the reaction temperature is not lower than
300.degree. C. and not higher than 750.degree. C., more preferably
not lower than 400.degree. C. and not higher than 650.degree. C.
Where the reaction temperature is lower than 300.degree. C.,
activity of the catalyst is not sufficient. Where the reaction
temperature exceeds 750.degree. C., formation rate of the
carbonaceous deposits is fast, catalytic activity is reduced
rapidly, and change of the catalyst such as collapse of the zeolite
structure occurs.
[0083] In the method of producing lower hydrocarbons, DME and/or
methanol as a raw material may be diluted with steam, inert gas,
carbon dioxide or the like and is supplied to the alkaline-earth
metal compound-containing zeolite catalyst.
[0084] Especially, when lower hydrocarbons are synthesized
continuously using a fixed-bed reactor, the weight hourly space
velocity (WHSV), which is the ratio of the supplied quantity of DME
as a raw material to the quantity of the catalyst, is preferably
not less than 0.025 g-DME/(g-catalysthour) and not more than 50
g-DME/(g-catalysthour).
[0085] Where the WHSV is less than 0.025 g-DME/(g-catalysthour), it
is not cost effective since space time yield is reduced. On the
other hand, where the WHSV is higher than 50
g-DME/(g-catalysthour), catalytic lifetime and catalytic activity
are not sufficient.
[0086] The lower hydrocarbons generated on the alkaline-earth metal
compound-containing zeolite catalyst flow out from the reactor, and
can be separated to objective products in accordance with
generally-known separation-purification method.
[0087] In the method for producing lower hydrocarbons, by using the
alkaline-earth metal compound-containing zeolite catalyst of the
present invention, it is possible to synthesize lower hydrocarbons
from DME and/or methanol at a high yield.
Second Embodiment
[0088] An embodiment of a method of regenerating an alkaline-earth
metal compound-containing zeolite catalyst of the present invention
is explained in the following.
[0089] It should be understood that this embodiment is an example
for providing better understanding of the scope of the present
invention and the present invention is not limited to the
description of this embodiment.
[0090] A method of regenerating alkaline-earth metal compound
containing zeolite catalyst according to the present invention is a
method for regenerating alkaline-earth metal compound containing
zeolite catalyst used for synthesizing lower hydrocarbons from DME
and/or methanol. The method includes a step of calcining an
alkaline-earth metal compound-containing zeolite catalyst of the
present invention in a flow containing oxygen and steam.
[0091] In the method of regenerating an alkaline-earth metal
compound-containing zeolite catalyst according to the present
invention, after performing synthesis of lower hydrocarbons from
one or both of DME and methanol for a certain period of time
utilizing the alkaline-earth metal compound-containing zeolite
catalyst, the alkaline-earth metal compound-containing zeolite
catalyst is calcined in a flow that contains oxygen and steam,
thereby regenerating catalytic activity.
[0092] In the method of regenerating an alkaline-earth metal
compound-containing zeolite catalyst according to the present
invention, proportion of the flow rate of steam relative to the
flow rate of oxygen in the flow containing oxygen and steam is
preferably not less than 5 and not more than 2000, more preferably,
not less than 15 and not more than 1000.
[0093] Where the proportion of the flow rate of steam relative to
the flow rate of oxygen is less than 5, oxygen is not diluted
sufficiently, and temperature of catalyst bed is increased by
combustion heat caused by burning carbonaceous deposits on the
catalyst, thereby causing a possible change of the catalyst, such
as collapse of the structure. In addition, it is possible that an
effect of steam treatment cannot be obtained sufficiently. On the
other hand, where the proportion of the flow rate of steam relative
to the flow rate of oxygen exceeds 2000, because of too low oxygen
concentration, burning the carbonaceous deposits on the catalyst
occurs slowly, and long time is required for regenerating the
catalyst.
[0094] In the method of regenerating an alkaline-earth metal
compound-containing zeolite catalyst according to the present
invention, the flow containing oxygen and steam may contain a
recycled exhaust gas from the reactor being used for regenerating
the catalyst, and inert gas such as carbon dioxide and argon
gas.
[0095] In the method of regenerating an alkaline-earth metal
compound-containing zeolite catalyst according to the present
invention, it is preferable that a temperature for calcining the
alkaline-earth metal compound-containing zeolite catalyst is
preferably not lower than 400.degree. C. and not higher than
700.degree. C., more preferably, not lower than 450.degree. C. and
not higher than 650.degree. C.
[0096] Where the temperature for calcining the alkaline-earth metal
compound-containing zeolite catalyst is less than 400.degree. C.,
carbonaceous deposits on the catalysts cannot be burned, and
catalytic activity cannot be recovered sufficiently. On the other
hand, where the temperature for calcining the alkaline-earth metal
compound-containing zeolite catalyst exceeds 700.degree. C., change
of the catalyst such as collapse of zeolite structure may
occur.
[0097] The period for calcining the alkaline-earth metal
compound-containing zeolite catalyst at the above-described
temperature range is preferably not shorter than 3 hours and not
longer than 300 hours, more preferably, not shorter than 5 hours
and not longer than 150 hours.
[0098] Where the period for calcining the alkaline-earth metal
compound-containing zeolite catalyst is shorter than 3 hours,
carbonaceous deposits on the catalyst cannot be burned
sufficiently, and catalytic activity cannot be recovered
sufficiently. On the other hand, where the period for calcining the
alkaline-earth metal compound containing zeolite catalyst exceeds
300 hours, since the catalyst is exposed to the flow containing
oxygen and steam for a long time, dealumination of the zeolite
proceeds resulting in reduction of catalytic lifetime.
[0099] A method of regenerating alkaline-earth metal compound
containing zeolite catalyst according to the invention is a method
for regenerating alkaline-earth metal compound containing zeolite
catalyst used for synthesizing lower hydrocarbons from DME and/or
methanol. In this method, by calcining the alkaline-earth metal
compound-containing zeolite catalyst in a flow that contains oxygen
and steam, it is possible to improve the lifetime of the catalyst.
Therefore, frequency of regenerating the catalyst is reduced,
resulting in reduction of cost for synthesizing lower hydrocarbons
from DME and/or methanol. In addition, in the time of regenerating
the catalyst, steam may be used as a dilution gas. Therefore,
requirement for extra facilities such as a cryogenic air separator
for nitrogen production can be avoided.
Example
Example of the First Embodiment
[0100] The present invention is explained in detail based on the
following examples. However, it should be understood that the
present invention is not limited to the following examples.
Preparation of Zeolite Catalyst
Experimental Example 1
[0101] 100 g of an ammonium type MFI-structure zeolite (CBV15014G
provided by Zeolyst International) having a molar ratio of Si/Al of
75 was calcined at 550.degree. C. and proton-type MFI-structure
zeolite was obtained. Hereafter, this catalyst is referred to as
catalyst A.
Experimental Example 2
[0102] The catalyst A in an amount of 100 g was mixed with 5.0 g of
calcium carbonate (CaCO.sub.3) under solid state and a mixture of
both materials was prepared. The mixture was calcined at
550.degree. C. for 6 hours in air. The thus obtained catalyst is
hereafter referred to as catalyst B.
Experimental Example 3
[0103] 100 g of the above-described ammonium type MFI structure
zeloite was mixed with 5.0 g of calcium carbonate. After adding an
appropriate amount of ion-exchanged water, the mixture was kneaded
and a mixed body was prepared. After drying the mixed body at
120.degree. C., the mixed body was calcined at 550.degree. C. for
12 hours in air. The thus obtained catalyst is hereafter referred
to as catalyst C.
Experimental Example 4
[0104] 100 g of the above-described ammonium type MFI structure
zeloite was mixed with 28 g of boehmite (containing 70% of
Al.sub.2O.sub.3). After adding an appropriate amount of
ion-exchanged water, the mixture was kneaded and a mixed body was
prepared. The mixed body was extruded using an extruder. A shaped
catalyst obtained by the extrusion molding was dried at 120.degree.
C., and was calcined at 550.degree. C. for 12 hours in the air. The
thus obtained catalyst is hereafter referred to as catalyst D.
Experimental Example 5
[0105] 100 g of the above-described ammonium type MFI structure
zeolite was mixed with 28 g of the above-described boehmite and 5.0
g of calcium carbonate. After adding an appropriate amount of
ion-exchanged water, the mixture was kneaded and a mixed body was
prepared. The mixed body was extruded using an extruder. A shaped
catalyst obtained by the extrusion molding was dried at 120.degree.
C., and was calcined at 550.degree. C. for 12 hours in the air. The
thus obtained catalyst is hereafter referred to as catalyst E.
Experimental Example 6
[0106] 100 g of the above-described ammonium type MFI structure
zeloite was mixed with 28 g of the above-described boehmite and 25
g of calcium carbonate. After adding an appropriate amount of
ion-exchanged water, the mixture was kneaded and a mixed body was
prepared. The mixed body was extruded using an extruder. A shaped
catalyst obtained by the extrusion molding was dried at 120.degree.
C., and was calcined at 550.degree. C. for 12 hours in the air.
Thus obtained catalyst is hereafter referred to as catalyst F.
Experimental Example 7
[0107] 100 g of the above-described ammonium type MFI structure
zeloite was mixed with 262 g of the above-described boehmite and
5.0 g of calcium carbonate. After adding an appropriate amount of
ion-exchanged water, the mixture was kneaded and a mixed body was
prepared. The mixed body was extruded using an extruder. A shaped
catalyst obtained by the extrusion molding was dried at 120.degree.
C., and was calcined at 550.degree. C. for 12 hours in the air.
Thus obtained catalyst is hereafter referred to as catalyst G.
Evaluation of Steam Resistance of Catalysts
Comparative Example A1
[0108] In order to evaluate the steam resistance, the catalyst A
obtained by the Experimental Example 1 was subjected to the
following treatment.
[0109] The catalyst A was evacuated at 400.degree. C. for 3 hours.
After that, .sup.27Al-MAS-NMR spectrum of the catalyst A was
measured using a NMR spectrometer (Bruker DRX-400), thereby
performing quantitative analysis of the amount of tetrahedral
aluminum in zeolite framework per unit mass of zeolite. The
measured amount of tetrahedral aluminum in zeolite framework in
Comparative Example A1 was defined as 100.
Comparative Example A2
[0110] The catalyst A was subjected to a steam treatment by
exposing the catalyst to an atmosphere having steam partial
pressure of 0.35 MPa, nitrogen partial pressure of 0.15 MPa, at
530.degree. C., for 48 hours.
[0111] The catalyst A treated with steam was evacuated at
400.degree. C. for 3 hours. After that, .sup.27Al-MAS-NMR spectrum
of the catalyst A treated with steam was measured using an NMR
spectrometer (Bruker DRX-400), thereby performing quantitative
analysis of the amount of tetrahedral aluminum in zeolite framework
per unit mass of zeolite. The relative amount of the tetrahedral
aluminum in the Comparative Example A2 compared to the amount of
tetrahedral aluminum in the Comparative Example A1 is shown in
Table 1.
Comparative Example A3
[0112] The catalyst B obtained by the Experimental Example 2 was
subjected to the same treatments as the Comparative Example A1, and
in the same manner as described-above, relative amount of the
tetrahedral aluminum in the Comparative Example A3 compared to the
amount of tetrahedral aluminum in the Comparative Example A1 was
determined. The result is shown in Table 1.
Comparative Example A4
[0113] The catalyst B was subjected to the same treatments as the
Comparative Example A2, and in the same manner as described-above,
the relative amount of the tetrahedral aluminum in the Comparative
Example A4 compared to the amount of tetrahedral aluminum in the
Comparative Example A1 was determined. The result is shown in Table
1.
Comparative Example A5
[0114] The catalyst C obtained by the Experimental Example 3 was
subjected to the same treatments as the Comparative Example A1, and
in the same manner as described-above, the relative amount of the
tetrahedral aluminum in the Comparative Example A5 compared to the
amount of tetrahedral aluminum in the Comparative Example A1 was
determined. The result is shown in Table 1.
Comparative Example A6
[0115] The catalyst C was subjected to the same treatments as the
Comparative Example A2, and in the same manner as described-above,
the relative amount of the tetrahedral aluminum in the Comparative
Example A6 compared to the amount of tetrahedral aluminum in the
Comparative Example A1 was determined. The result is shown in Table
1.
Comparative Example A7
[0116] The catalyst D obtained by the Experimental Example 4 was
subjected to the same treatments as the Comparative Example A1, and
in the same manner as described-above, the relative amount of the
tetrahedral aluminum in the Comparative Example A7 compared to the
amount of tetrahedral aluminum in the Comparative Example A1 was
determined. The result is shown in Table 1.
Comparative Example A8
[0117] The catalyst D was subjected to the same treatments as the
Comparative Example A2, and in the same manner as described-above,
the relative amount of the tetrahedral aluminum in the Comparative
Example A8 compared to the amount of tetrahedral aluminum in the
Comparative Example A1 was determined. The result is shown in Table
1.
Comparative Example A9
[0118] The catalyst F obtained by the Experimental Example 6 was
subjected to the same treatments as the Comparative Example A1, and
in the same manner as described-above, the relative amount of the
tetrahedral aluminum in the Comparative Example A9 compared to the
amount of tetrahedral aluminum in the Comparative Example A1 was
determined. The result is shown in Table 1.
Comparative Example A10
[0119] The catalyst F was subjected to the same treatments as the
Comparative Example A2, and in the same manner as described-above,
the relative amount of the tetrahedral aluminum in the Comparative
Example A10 compared to the amount of tetrahedral aluminum in the
Comparative Example A1 was determined. The result is shown in Table
1.
Example A1
[0120] The catalyst E obtained by the Experimental Example 5 was
subjected to the same treatments as the Comparative Example A1, and
in the same manner as described-above, the relative amount of the
tetrahedral aluminum in the Example A1 compared to the amount of
tetrahedral aluminum in the Comparative Example A1 was determined.
The result is shown in Table 1.
Example A2
[0121] The catalyst E was subjected to the same treatments as the
Comparative Example A2, and in the same manner as described-above,
relative amount of the tetrahedral aluminum in the Example A2
compared to the amount of tetrahedral aluminum in the Comparative
Example A1 was determined. The result is shown in Table 1.
TABLE-US-00001 TABLE 1 Relative amount of tetrahedral aluminum (%)
Comparative Example A1 100 Comparative Example A2 6 Comparative
Example A3 104 Comparative Example A4 22 Comparative Example A5 100
Comparative Example A6 29 Comparative Example A7 115 Comparative
Example A8 36 Comparative Example A9 155 Comparative Example A10 63
Example A1 142 Example A2 86
[0122] Tetrahedral aluminum in the zeolite framework cause acid
sites, that is catalytic active sites. Where a catalyst is exposed
to steam atmosphere, the tetrahedral aluminum are eliminated from
the framework to lead a decrease of acid sites and the catalytic
activity. Therefore, the catalyst having a large amount of residual
tetrahedral aluminum after the exposure to steam atmosphere can be
regarded as a catalyst having high steam resistance, and not likely
to subject the elimination of tetrahedral aluminum from the zeolite
framework.
[0123] With respect to Comparative Examples A1 and A2, it was
confirmed that the amount of tetrahedral aluminum in the catalyst A
decreased to 6% after exposing the catalyst to an atmosphere having
steam partial pressure of 0.35 MPa, nitrogen partial pressure of
0.15 MPa, at 530.degree. C., for 48 hours.
[0124] With respect to Comparative Examples A3 and A4, it was
confirmed that the relative amount of tetrahedral aluminum in the
catalyst B decreased to 22% after exposing the catalyst to an
atmosphere having steam partial pressure of 0.35 MPa, nitrogen
partial pressure of 0.15 MPa, at 530.degree. C., for 48 hours.
[0125] It is considered that calcium carbonate added to the
catalyst B inhibited the elimination of tetrahedral aluminum from
the zeolite framework.
[0126] With respect to Comparative Examples A5 and A6, it was
confirmed that the relative amount of tetrahedral aluminum in the
catalyst C decreased to 29% after exposing the catalyst to an
atmosphere having steam partial pressure of 0.35 MPa, nitrogen
partial pressure of 0.15 MPa, at 530.degree. C., for 48 hours.
[0127] The catalyst C was prepared by kneading MFI zeolite and
calcium carbonate in the presence of water, and calcining the
mixture. Therefore, compared to catalyst B in which raw materials
were mixed in a solid state, it is considered that calcium
carbonate were highly dispersed into the micropore of the zeolite
and it would be more effective to prevent the elimination of
tetrahedral aluminum from the zeolite framework.
[0128] In Comparative Example A7, catalyst D showed the relative
amount of tetrahedral aluminum of 115%, which was increased
compared to that in the catalyst A. It is considered that because
of the addition of boehmite, aluminum atoms are inserted into the
zeolite framework during the calcination.
[0129] In Comparative Example A8, it was confirmed that the amount
of tetrahedral aluminum in the catalyst D decreased to 36% after
exposing the catalyst to an atmosphere having steam partial
pressure of 0.35 MPa, nitrogen partial pressure of 0.15 MPa, at
530.degree. C., for 48 hours. The elimination of tetrahedral
aluminum from Catalyst D was suppressed compared with that in
Catalyst A. Aluminum oxide and/or aluminum hydroxide species would
exist in the zeolite catalyst after calcining the zeolite and
boehmite mixture. The aluminum oxide and/or aluminum hydroxide
species may inhibit the elimination of tetrahedral aluminum.
[0130] In Comparative Example A9, catalyst F showed a relative
amount of tetrahedral aluminum of 155%, which was more than the
catalyst A. The addition of boehmite may cause the insertion of
aluminum into the zeolite framework during calcination.
[0131] In Comparative Example A10, it was confirmed that the amount
of tetrahedral aluminum in the catalyst F decreased to 63% after
exposing the catalyst to an atmosphere having steam partial
pressure of 0.35 MPa, nitrogen partial pressure of 0.15 MPa, at
530.degree. C., for 48 hours. In Comparative A10, it was confirmed
that by adding boehmite and calcium carbonate to the zeolite, it
was possible to obtain a catalyst which was not likely to subject
elimination of tetrahedral aluminum and had high steam
resistance.
[0132] In Example A1, catalyst E showed a relative amount of
tetrahedral aluminum of 142%. It was confirmed that the residual
amount of tetrahedral aluminum in the catalyst E was increased
compared to the catalyst A. It is considered that because of the
addition of boehmite, aluminum are inserted into the zeolite
framework during the calcination.
[0133] In Example A2, it was confirmed that the amount of
tetrahedral aluminum in the zeolite framework decreased to 86%
after exposing the catalyst to an atmosphere having steam partial
pressure of 0.35 MPa, nitrogen partial pressure of 0.15 MPa, at
530.degree. C., for 48 hours. In Example A2, composing the MFI
zeolite with the appropriate amount of aluminum oxide and/or
aluminum hydroxide and calcium carbonate, can yield the most steam
rersistant catalyst which has the least possibility of the
elimination of tetrahedral aluminum from the zeolite framework
among all catalysts in Table 1.
Test of Catalytic Performance
[0134] In order to test the catalytic performance of catalysts A to
G obtained in Experimental Examples 1 to 7, lower hydrocarbons were
synthesized from DME utilizing the catalysts A to G. Here,
catalytic lifetime was defined as an elapsed time from the time the
reaction started to the time the conversion of DME became less than
99.0%. Yields (mass %) of propylene, methane, and yield of carbon
monoxide were analyzed by gas chromatograph at 10-15 hours after
the beginning of the reaction. The yield of each product was based
on the weight of carbon atoms contained in the supplied DME and/or
methanol.
Comparative Example A11
[0135] Performance of the catalyst A was tested with an isothermal
reactor. DME and nitrogen were mixed together at flow rates of
1,272 Ncm.sup.3/hour and 1,272 Ncm.sup.3/hour, respectively. Then,
the resulting mixture was transferred to an isothermal reactor, and
reacted with the catalyst A at 530.degree. C. under atmospheric
pressure. The weight hourly space velocity (WHSV), which is the
ratio of the supplied quantity of DME as a raw material to the
quantity of the catalyst, was set to be 9.6 g-DME/(g-catalysthour).
Relative catalytic lifetime, and yields (in mass %) of propylene,
methane and carbon monoxide are shown in Table 2. The relative
catalytic lifetime denotes a lifetime compared to the catalytic
lifetime in Comparative Example A11 which was defined as 100.
Comparative Example A12
[0136] Catalyst A was treated with steam for 24 hours by exposing
the catalyst to an atmosphere having steam partial pressure of 0.08
MPa, nitrogen partial pressure of 0.02 MPa, at 530.degree. C.
[0137] Performance of the steam-treated catalyst A was tested with
an isothermal reactor. DME and nitrogen were mixed together at flow
rates of 1,272 Ncm.sup.3/hour and 1,272 Ncm.sup.3/hour,
respectively. Then, the resulting mixture was transferred to an
isothermal reactor, and reacted with the steam-treated catalyst A
at 530.degree. C. under atmospheric pressure. The weight hourly
space velocity (WHSV), which is the ratio of the supplied quantity
of DME as a raw material to the quantity of the catalyst, was set
to be 9.6 g-DME/(g-catalysthour). Relative catalytic lifetime, and
yields (in mass %) of propylene, methane and carbon monoxide are
shown in Table 2.
Comparative Example A13
[0138] Catalyst A was treated with steam for 48 hours by exposing
the catalyst to an atmosphere having steam partial pressure of 0.35
MPa, nitrogen partial pressure of 0.15 MPa, at 530.degree. C.
[0139] Performance of the steam-treated catalyst A was tested with
an isothermal reactor. DME and nitrogen were mixed together at flow
rates of 1,272 Ncm.sup.3/hour and 1,272 Ncm.sup.3/hour,
respectively. Then, the resulting mixture was transferred to an
isothermal reactor, and reacted with the steam-treated catalyst A
at 530.degree. C. under atmospheric pressure. The weight hourly
space velocity (WHSV), which is the ratio of the supplied quantity
of DME as a raw material to the quantity of the catalyst, was set
to be 9.6 g-DME/(g-catalysthour). Relative catalytic lifetime, and
yields (in mass %) of propylene, methane and carbon monoxide are
shown in Table 2.
Comparative Example A14
[0140] Catalyst A was treated with steam for 96 hours by exposing
the catalyst to an atmosphere having steam partial pressure of 0.35
MPa, nitrogen partial pressure of 0.15 MPa, at 530.degree. C.
[0141] Performance of the steam-treated catalyst A was tested with
an isothermal reactor. DME and nitrogen were mixed together at flow
rates of 1,272 Ncm.sup.3/hour and 1,272 Ncm.sup.3/hour,
respectively. Then, the resulting mixture was transferred to an
isothermal reactor, and reacted with the steam-treated catalyst A
at 530.degree. C. under atmospheric pressure. The weight hourly
space velocity (WHSV), which is the ratio of the supplied quantity
of DME as a raw material to the quantity of the catalyst, was set
to be 9.6 g-DME/(g-catalysthour). The relative catalytic lifetime,
and yields (in mass %) of propylene, methane and carbon monoxide
are shown in Table 2.
Comparative Example A15
[0142] Performance of the Catalyst B was tested in the same manner
as in Comparative Example A11. The relative catalytic lifetime, and
yields (in mass %) of propylene, methane and carbon monoxide are
shown in Table 2.
Comparative Example A16
[0143] Performance of the Catalyst B was tested in the same manner
as in Comparative Example A12. The relative catalytic lifetime, and
yields (in mass %) of propylene, methane and carbon monoxide are
shown in Table 2.
Comparative Example A 17
[0144] Performance of the Catalyst B was tested in the same manner
as in Comparative Example A13. The relative catalytic lifetime, and
yields (in mass %) of propylene, methane and carbon monoxide are
shown in Table 2.
Comparative Example A18
[0145] Performance of the Catalyst C was tested in the same manner
as in Comparative Example A11. The relative catalytic lifetime, and
yields (in mass %) of propylene, methane and carbon monoxide are
shown in Table 2.
Comparative Example A19
[0146] Performance of the Catalyst C was tested in the same manner
as in Comparative Example A12. The relative catalytic lifetime, and
yields (in mass %) of propylene, methane and carbon monoxide are
shown in Table 2.
Comparative Example A20
[0147] Performance of the Catalyst C was tested in the same manner
as in Comparative Example A13. The relative catalytic lifetime, and
yields (in mass %) of propylene, methane and carbon monoxide are
shown in Table 2.
Comparative Example A21
[0148] Performance of the Catalyst C was tested in the same manner
as in Comparative Example A14. The relative catalytic lifetime, and
yields (in mass %) of propylene, methane and carbon monoxide are
shown in Table 2.
Comparative Example A22
[0149] Performance of the Catalyst D was tested in the same manner
as in Comparative Example A11. The relative catalytic lifetime, and
yields (in mass %) of propylene, methane and carbon monoxide are
shown in Table 2.
Comparative Example A23
[0150] Performance of the Catalyst D was tested in the same manner
as in Comparative Example A12. The relative catalytic lifetime, and
yields (in mass %) of propylene, methane and carbon monoxide are
shown in Table 2.
Comparative Example A24
[0151] Performance of the Catalyst D was tested in the same manner
as in Comparative Example A13. The relative catalytic lifetime, and
yields (in mass %) of propylene, methane and carbon monoxide are
shown in Table 2.
Comparative Example A25
[0152] Performance of the Catalyst D was tested in the same manner
as in Comparative Example A14. The relative catalytic lifetime, and
yields (in mass %) of propylene, methane and carbon monoxide are
shown in Table 2.
Comparative Example A26
[0153] Performance of the Catalyst F was tested in the same manner
as in Comparative Example A11. The relative catalytic lifetime, and
yields (in mass %) of propylene, methane and carbon monoxide are
shown in Table 2.
Comparative Example A27
[0154] Performance of the Catalyst F was tested in the same manner
as in Comparative Example A13. The relative catalytic lifetime, and
yields (in mass %) of propylene, methane and carbon monoxide are
shown in Table 2.
Example A3
[0155] Performance of the Catalyst E was tested in the same manner
as in Comparative Example A11. The relative catalytic lifetime, and
yields (in mass %) of propylene, methane and carbon monoxide are
shown in Table 2.
Example A4
[0156] Performance of the Catalyst E was tested in the same manner
as in Comparative Example A12. The relative catalytic lifetime, and
yields (in mass %) of propylene, methane and carbon monoxide are
shown in Table 2.
Example A5
[0157] Performance of the Catalyst E was tested in the same manner
as in Comparative Example A13. The relative catalytic lifetime, and
yields (in mass %) of propylene, methane and carbon monoxide are
shown in Table 2.
Example A6
[0158] Performance of the Catalyst E was tested in the same manner
as in Comparative Example A14. The relative catalytic lifetime, and
yields (in mass %) of propylene, methane and carbon monoxide are
shown in Table 2.
Example A7
[0159] Performance of the Catalyst G was tested in the same manner
as in Comparative Example A12. The relative catalytic lifetime, and
yields (in mass %) of propylene, methane and carbon monoxide are
shown in Table 2.
TABLE-US-00002 TABLE 2 Yield of Yield of Yield of Relative
propylene methane CO lifetime (mass %) (mass %) (mass %)
Comparative Example A11 100 34 3.3 0.35 Comparative Example A12 346
42 1.9 0.20 Comparative Example A13 0 32 1.1 0.05 Comparative
Example A14 0 15 1.1 0.03 Comparative Example A15 142 43 1.8 0.80
Comparative Example A16 546 42 0.9 0.60 Comparative Example A17 371
42 0.8 0.65 Comparative Example A18 268 42 1.7 0.22 Comparative
Example A19 478 44 0.7 0.13 Comparative Example A20 927 44 0.6 0.00
Comparative Example A21 0 38 1.1 0.15 Comparative Example A22 99 32
6.0 0.50 Comparative Example A23 591 42 0.9 0.25 Comparative
Example A24 544 44 0.8 0.06 Comparative Example A25 0 36 0.7 0.08
Comparative Example A26 693 39 1.8 3.10 Comparative Example A27
1033 46 1.0 1.56 Example A3 306 42 1.5 0.83 Example A4 440 42 0.8
0.07 Example A5 900 46 0.7 0.07 Example A6 514 42 0.7 0.00 Example
A7 221 40 0.9 0.10
[0160] FIG. 1 shows the relative lifetime of catalysts versus the
extent of steam treatments.
[0161] In FIG. 1, the horizontal axis denotes the extent of steam
treatment which was defined by the product of steam partial
pressure and the duration of the steam treatment. The vertical axis
of FIG. 1 denotes the relative catalytic lifetime of catalysts A-G
in Comparative Examples A11-A27 and Examples A3-A7 compared to the
lifetime of catalyst A in Comparative Example A11 which was defined
as 100.
[0162] From the results shown in Table 2 and FIG. 1, it was
confirmed that catalytic lifetimes of catalysts A to E were
improved by treating the catalysts with steam under mild condition
by exposing to an atmosphere having steam partial pressure of 0.08
MPa, nitrogen partial pressure of 0.02 MPa, at 530.degree. C., for
24 hours (Comparative Examples A11, A12, A15, A16, A18, A19, A22,
A23, Examples A3, A4). This improvement can be explained by
moderate reduction of acid sites (active sites) in zeolite caused
by elimination of the tetrahedral aluminum. In catalyst D and
catalyst E, steaming can also reduce the acid sites on alumina,
which contribute undesirable side reactions, and improve the
catalytic lifetime.
[0163] After the steam treatment for exposing a catalyst for 48
hours to an atmosphere having steam partial pressure of 0.35 MPa,
nitrogen partial pressure of 0.15 MPa, at 530.degree. C., catalytic
lifetime of the catalyst A was reduced to 0, and catalytic
lifetimes of catalyst B and catalyst D were decreased. On the other
hand, catalytic lifetimes of catalyst C and catalyst E were further
improved (Comparative Example A13, A17, A20, A24, Example A5).
[0164] After the steam treatment for exposing a catalyst for 96
hours to an atmosphere having steam partial pressure of 0.35 MPa,
nitrogen partial pressure of 0.15 MPa, at 530.degree. C., catalytic
lifetimes of catalyst C and catalyst D were reduced to 0, and
catalytic lifetime of catalyst E was decreased (Comparative Example
A21, A25, Example A6).
[0165] The above-described trend can be explained by the
elimination of the tetrahedral aluminum from the zeolite framework
accompanied by the steam treatment, that is, reduction of acid
sites (active sites). Where catalysts A to E are treated with steam
for relatively short duration, the moderate reduction of acid sites
depress the formation of carbonaceous deposits, thereby increasing
catalytic lifetime. On the other hand, where the catalysts are
further treated with steam for relatively long duration, acid sites
are decreased to too low level, thereby leaking DME in early stage
and reducing catalytic lifetime. A catalyst that exhibits long
catalytic lifetime even after the severe steam treatment is not
likely to subject elimination of tetrahedral aluminum from the
zeolite framework and has high steam resistance.
[0166] From the result of FIG. 1, steam resistance of catalysts A
to E can be expressed as catalyst E>catalyst C>catalyst
D>catalyst B>catalyst A. This order approximately corresponds
with the order of residual proportion of tetrahedral aluminum
obtained by .sup.27Al-MAS-NMR spectra (Table 1).
[0167] Catalyst F had long catalytic lifetime even when the steam
treatment was not performed (Comparative Example A26). It is
considered that a large content of calcium carbonate contribute the
improvement of the catalytic lifetime. After treating the catalyst
F with steam by exposing to an atmosphere having steam partial
pressure of 0.35 MPa, nitrogen partial pressure of 0.15 MPa, at
530.degree. C., for 48 hours, catalytic lifetime of the catalyst F
was increased and showed a long catalytic lifetime comparable to
catalyst C and catalyst E (Comparative Example 27).
[0168] By the use of catalysts A, C, D, and E that were not treated
with steam, methane of not less than 1.0 mass % and/or carbon
monoxide of not less than 0.3 mass % were generated (Comparative
Examples A11, A18, A22, and Example A3). Even after the catalyst A
treated with steam, yield of methane was not less than 1.0 mass %
(Comparative Examples A12 to A14). When catalysts C, D, E were
treated with steam to an appropriate degree such that each catalyst
did not lose its activity, yield of methane was less than 1.0 mass
%, and yield of carbon monoxide was less than 0.3 mass %
(Comparative Examples A19, A20, A23, A24, and Examples A4 to
A6).
[0169] When catalyst B was used without the steam treatment, yield
of methane was 1.8 mass %, and yield of carbon monoxide was 0.80
mass % (Comparative Example A15). When catalyst B was used after
the steam treatment, yield of methane was 0.8 to 0.9 mass % and
yield of carbon monoxide was 0.60 to 0.65 mass %. Therefore, it was
confirmed that even when the catalyst B was treated with steam,
these side reactions could not be inhibited sufficiently
(Comparative Examples A16, A17).
[0170] When catalyst F was used without the steam treatment, yield
of methane was 1.8 mass %, and yield of carbon monoxide was 3.10
mass % which was higher than the case of using the other catalysts
(Comparative Example A26). It was considered that high calcium
content in catalyst F resulted in the decomposition of DME on the
basic sites.
[0171] When catalyst F was used after the steam treatment, yield of
methane was 1.0 mass % and yield of carbon monoxide was 1.56 mass
%. Therefore, it was confirmed that even when the catalyst F was
treated with steam, these side reactions could not be inhibited
sufficiently (Comparative Examples A27).
[0172] By using catalyst G, yield of propylene was 40 mass %, yield
of methane was 0.9 mass %, and yield of carbon monoxide was 0.10
mass % (Example A7).
[0173] Based on the above-described results, the catalyst E, which
was obtained by mixing ammonium type MFI structure zeolite with
boehmite and appropriate amount of calcium carbonate, kneading the
mixture with appropriate amount of ion-exchanged water, drying and
calcining the mixture, had the highest steam resistance. In
addition, by treating the catalyst E with steam, catalytic lifetime
was largely enhanced and side reactions such as generation of
methane and generation of carbon monoxide could be effectively
inhibited.
[0174] The catalyst F, which was obtained by mixing ammonium type
MFI structure zeolite with boehmite and a large amount of calcium
carbonate, kneading the mixture with appropriate amount of
ion-exchanged water, drying and calcining the mixture, had
relatively high steam resistance. However, even after the steam
treatment, side reactions such as generation of methane and
generation of carbon monoxide could not be inhibited by the use of
the catalyst F. Even though recycled in a reactor, methane and
carbon monoxide have poor reactivity and are not converted to
olefin. Therefore decomposition reaction for generating methane and
carbon monoxide is not desirable. It is understood that the
catalyst F is not appropriately used for a reaction for generating
lower hydrocarbons from DME and/or methanol.
[0175] From the results of evaluation of steam resistance of the
catalysts and catalytic performance tests, the following can be
proposed.
[0176] In catalyst C, which was obtained by mixing ammonium type
MFI-structure zeolite with appropriate amount of calcium carbonate,
kneading the mixture with ion-exchanged water, drying and calcining
the mixture, elimination of tetrahedral aluminum from the zeolite
framework was inhibited by the calcium compound, resulting in
higher steam resistance than that of catalyst A consisting of
proton type MFI-structure zeolite.
[0177] In catalyst D, which was obtained by mixing ammonium type
MFI-structure zeolite with boehmite, kneading the mixture with
ion-exchanged water, drying and calcining the mixture, elimination
of aluminum from the zeolite framework was inhibited by the effect
of aluminum oxide and/or aluminum hydroxide, resulting in higher
steam resistance than that of catalyst A consisting of proton type
MFI-structure zeolite.
[0178] The catalyst E, which was obtained by mixing ammonium type
MFI structure zeolite with boehmite and appropriate amount of
calcium carbonate, kneading the mixture with ion-exchanged water,
drying and calcining the mixture, had the highest steam resistance
by the effects of calcium compound and aluminum oxide and/or
aluminum hydroxide.
[0179] When the catalyst E was used in the reaction without steam
treatment, yields of methane and carbon monoxide were relatively
high and catalytic lifetime was not so long. By treating catalyst E
with steam, side reactions were inhibited and catalytic lifetime
was largely enhanced.
[0180] The catalyst F, which was obtained by mixing ammonium type
MFI structure zeolite with boehmite and a large amount of calcium
carbonate, kneading the mixture with ion-exchanged water, drying
and calcining the mixture, had lower steam resistance than that of
catalyst E (Table 1). In addition, in the reaction using the
catalyst F, methane and carbon monoxide showed high yields. Even
after treating catalyst F with steam, methane and carbon monoxide
showed high yields in the reaction using catalyst F.
Example of the Second Embodiment
Preparation of Zeolite Catalysts
[0181] Zeolite catalysts D and E were prepared in the same manners
as above-described Experimental Examples 4 and 5, respectively.
Experimental Example 8
[0182] In accordance with the method of preparing a zeolite
catalyst disclosed in a Patent Reference (Japanese Unexamined
Patent Application, First Publication No. 2005-138000),
Ca-containing MFI-structure zeolite catalyst was obtained. This
catalyst is hereafter referred to as catalyst H.
[Test of Catalytic Performance]
[0183] In order to test catalytic performance of catalysts D, E,
and H obtained in Experimental Examples 4, 5, and 8, lower
hydrocarbons were synthesized from DME utilizing the catalysts D,
E, and H.
[0184] Here, catalytic lifetime was defined as an elapsed time from
the time the reaction started to the time the conversion of DME
became less than 99.0%.
Comparative Example B1
[0185] Catalyst D was treated with steam for 24 hours by exposing
the catalyst to an atmosphere having a steam partial pressure of
0.08 MPa, nitrogen partial pressure of 0.02 MPa, at 530.degree.
C.
[0186] Performance of the steam-treated catalyst D was tested with
an isothermal reactor. DME and nitrogen were mixed together at flow
rates of 1,272 Ncm.sup.3/hour and 1,272 Ncm.sup.3/hour,
respectively. Then, the resulting mixture was transferred to an
isothermal reactor, and reacted with the steam-treated catalyst D
at 530.degree. C. under atmospheric pressure. The weight hourly
space velocity (WHSV), which is the ratio of the supplied quantity
of DME as a raw material to the quantity of the catalyst, was set
to be 9.6 g-DME/(g-catalysthour). DME and nitrogen were supplied to
the reactor until the DME conversion was decreased to 5% or
less.
Comparative Example B2
[0187] Air and nitrogen were mixed together at flow rates of
143Ncm.sup.3/hour and 1,272 Ncm.sup.3/hour, respectively. Then, the
resulting mixture was transferred to the isothermal reactor,
thereby burning carbonaceous deposits on the catalyst D used in
Comparative Example B1 at 550.degree. C. under atmospheric
pressure. After that, catalytic performance was tested in the same
manner as in Comparative Example B1. Relative catalytic lifetime of
Comparative Example B2 compared to the catalytic lifetime of
Comparative Example B1 defined as 100 was shown in Table 3.
Example B1
[0188] Catalyst D was treated with steam for 24 hours by exposing
the catalyst to an atmosphere having a steam partial pressure of
0.08 MPa, nitrogen partial pressure of 0.02 MPa, at 530.degree.
C.
[0189] Using the steam-treated catalyst D, catalytic performance
was tested in the same manner as in Comparative Example B1.
Example B2
[0190] Air and steam were mixed together at flow rates of 143
Ncm.sup.3/hour and 1,272 Ncm.sup.3/hour, respectively. Then, the
resulting mixture was transferred to the isothermal reactor,
thereby burning carbonaceous deposits on the catalyst D used in
Example B1 at 550.degree. C. under atmospheric pressure. After
that, catalytic performance was tested in the same manner as in
Comparative Example B1. Relative catalytic lifetime of Example B2
compared to the catalytic lifetime of Example B1 defined as 100 was
shown in Table 3.
Comparative Example B3
[0191] Catalyst E was treated with steam for 24 hours by exposing
the catalyst to an atmosphere having a steam partial pressure of
0.08 MPa, nitrogen partial pressure of 0.02 MPa, at 530.degree.
C.
[0192] Using the steam-treated catalyst E, catalytic performance
was tested in the same manner as in Comparative Example B1.
Comparative Example B4
[0193] Air and nitrogen were mixed together at flow rates of 143
Ncm.sup.3/hour and 1,272 Ncm.sup.3/hour, respectively. Then, the
resulting mixture was transferred to the isothermal reactor,
thereby burning carbonaceous deposits on the catalyst E used in
Comparative Example B3 at 550.degree. C. under atmospheric
pressure. After that, catalytic performance was tested in the same
manner as in Comparative Example B1. Relative catalytic lifetime of
Comparative Example B4 compared to the catalytic lifetime of
Comparative Example B3 defined as 100 was shown in Table 3.
Example B3
[0194] Catalyst E was treated with steam for 24 hours by exposing
the catalyst to an atmosphere having a steam partial pressure of
0.08 MPa, nitrogen partial pressure of 0.02 MPa, at 530.degree.
C.
[0195] Using the steam-treated catalyst E, catalytic performance
was treated in the same manner as in Comparative Example B1.
Example B4
[0196] Air and steam were mixed together at flow rates of 143
Ncm.sup.3/hour and 1,272 Ncm.sup.3/hour, respectively. Then, the
resulting mixture was transferred to the isothermal reactor,
thereby burning carbonaceous deposits on the catalyst E used in
Example B3 at 550.degree. C. under atmospheric pressure. After
that, in the same manner as in Comparative Example B1, test of
catalytic performance was performed in an isothermal reactor.
Relative catalytic lifetime of Example B4 compared to the catalytic
lifetime of Example B3 defined as 100 was shown in Table 3.
Comparative Example B5
[0197] Catalyst H was treated with steam for 24 hours by exposing
the catalyst to an atmosphere having a steam partial pressure of
0.08 MPa, nitrogen partial pressure of 0.02 MPa, at 530.degree.
C.
[0198] Using the steam-treated catalyst H, catalytic performance
was tested in the same manner as in Comparative Example B1.
Comparative Example B6
[0199] Air of and nitrogen were mixed together at flow rates of 143
Ncm.sup.3/hour and 1,272 Ncm.sup.3/hour, respectively. Then, the
resulting mixture was transferred to the isothermal reactor,
thereby burning carbonaceous deposits on the catalyst H used in
Comparative Example B5 at 550.degree. C. under atmospheric
pressure. After that, catalytic performance was tested in the same
manner as in Comparative Example B1. Relative catalytic lifetime of
Comparative Example B6 compared to the catalytic lifetime of
Comparative Example B5 defined as 100 was shown in Table 3.
Comparative Example B7
[0200] Catalyst H was treated with steam for 24 hours by exposing
the catalyst to an atmosphere having a steam partial pressure of
0.08 MPa, nitrogen partial pressure of 0.02 MPa, at 530.degree.
C.
[0201] Using the steam-treated catalyst H, catalytic performance
was tested in the same manner as in Comparative Example B1.
Comparative Example B8
[0202] Air and steam were mixed together at flow rates of 143
Ncm.sup.3/hour and 1,272 Ncm.sup.3/hour, respectively. Then, the
resulting mixture was transferred to the isothermal reactor,
thereby burning carbonaceous deposits on the catalyst H used in
Comparative Example B7 at 550.degree. C. under atmospheric
pressure. After that, catalytic performance was tested in the same
manner as in Comparative Example B1. Relative catalytic lifetime of
Comparative Example B8 compared to the catalytic lifetime of
Comparative Example B7 defined as 100 was shown in Table 3.
TABLE-US-00003 TABLE 3 Relative lifetime Comparative Example B1 100
Comparative Example B2 89 Example B1 100 Example B2 110 Comparative
Example B3 100 Comparative Example B4 74 Example B3 100 Example B4
113 Comparative Example B5 100 Comparative Example B6 101
Comparative Example B7 100 Comparative Example B8 98
[0203] From the results shown in Table 3, the followings were
confirmed.
[0204] In Comparative Examples B1, B2, catalyst D was treated with
steam and was used in a synthetic reaction of lower hydrocarbons
from DME, and was subsequently regenerated in a flow of air and
nitrogen. In this case, catalytic lifetime was decreased after the
regeneration.
[0205] In Examples B1, B2, catalyst D was treated with steam and
was used in a synthetic reaction of lower hydrocarbons from DME,
and was subsequently regenerated in a flow of air and steam. In
this case, catalytic lifetime was improved by the regeneration.
[0206] In Comparative Examples B3, B4, catalyst E was treated with
steam and was used in a synthetic reaction of lower hydrocarbons
from DME, and was subsequently s regenerated in a flow of air and
nitrogen. In this case, catalytic lifetime was decreased after the
regeneration.
[0207] In Examples B3, B4, catalyst E was treated with steam and
was used in a synthetic reaction of lower hydrocarbons from DME,
and was subsequently regenerated in a flow of air and steam. In
this case, catalytic lifetime was improved by the regeneration.
[0208] In Comparative Examples B 5, B 6, catalyst H was treated
with steam and was used in a synthetic reaction of lower
hydrocarbons from DME, and was subsequently regenerated in a flow
of air and nitrogen. In this case, catalytic lifetime was almost
unchanged by the regeneration.
[0209] In Comparative Examples B7, B8, catalyst H was treated with
steam and was used in a synthetic reaction of lower hydrocarbons
from DME, and was subsequently regenerated in a flow of air and
steam. In this case, catalytic lifetime was almost unchanged by the
regeneration.
[0210] From the results described above, it is possible to derive
the following interpretations.
[0211] With respect to the Catalyst D, which is composed of
MFI-structure zeolite and aluminum oxide and/or aluminum hydroxide,
and Catalyst E, which is composed of MFI-structure zeolite, calcium
carbonate, and aluminum oxide and/or aluminum hydroxide, it is
possible to improve the catalytic lifetime after the regeneration
in a flow containing air and steam.
[0212] With respect to the Catalyst H, which is composed of
Ca-containing MFI-structure zeolite without aluminum oxide nor
aluminum hydroxide, catalytic lifetime did not largely change
before and after the regeneration, whether steam was supplied or
not during the regeneration.
[0213] From these observations, it is considered that regenerating
the catalysts in the presence of steam and air is effective for the
catalyst D, which is composed of MFI-structure zeolite and aluminum
oxide and/or aluminum hydroxide, and the catalyst E, which is
composed of MFI-structure zeolite, aluminum oxide and/or aluminum
hydroxide, and calcium carbonate. It is considered that the steam
may operate the nature of aluminum oxide and/or aluminum hydroxide
to improve the catalytic lifetime.
INDUSTRIAL APPLICABILITY
[0214] An alkaline-earth metal compound-containing zeolite catalyst
and method for preparing the same according to the present
invention may be applied to various processes such as synthetic
reaction of gasoline using methanol as the raw material (MTG
reaction), olefin cracking, fluid catalytic cracking (FCC),
hydrogen dewaxing, isomerization of paraffin, production of
aromatic hydrocarbon, alkylation of aromatic compound, oxidation
reaction using hydrogen peroxide, and production of ethanolamine
group.
[0215] A method of regenerating an alkaline-earth metal compound
containing zeolite catalyst according to the present invention may
be applied to regeneration step of catalyst in various processes
such as synthetic reaction of gasoline using methanol as the raw
material (MTG reaction), cracking or the like.
* * * * *