U.S. patent application number 09/293949 was filed with the patent office on 2001-05-24 for crystalline microporous and mesoporous metal silicates and use thereof.
This patent application is currently assigned to Steffen Hasenzahl. Invention is credited to HASENZAHL, STEFFEN, MANGOLD, HELMUT, ROLAND, ECKEHART, SCHOLZ, MARIO, THIELE, GEORG.
Application Number | 20010001656 09/293949 |
Document ID | / |
Family ID | 26026690 |
Filed Date | 2001-05-24 |
United States Patent
Application |
20010001656 |
Kind Code |
A1 |
HASENZAHL, STEFFEN ; et
al. |
May 24, 2001 |
CRYSTALLINE MICROPOROUS AND MESOPOROUS METAL SILICATES AND USE
THEREOF
Abstract
Microporous and mesoporous metal silicates are prepared by the
hydrothermal reaction of a silicon and metal source in the presence
of a template. The choice of raw materials influences the purity
and hence the catalytic activity of the products. A pyrogenic mixed
oxide is used as the silicon and metal source. Prepared products
have the composition (SiO.sub.2).sub.1-x(A.sub.mO.sub.n).sub.x,
where A is Ti, Al, B, V or Zr and x is 0.005 to 0.1. Shaped objects
of the microporous and mesoporous metal silicates are obtained
directly by using a shaped object of the pyrogenic mixed oxide. The
products obtained are used as oxidation catalysts.
Inventors: |
HASENZAHL, STEFFEN; (HANAU,
DE) ; MANGOLD, HELMUT; (RODENBACH, DE) ;
ROLAND, ECKEHART; (HARTSDALE, NY) ; SCHOLZ,
MARIO; (GRUNDAU, DE) ; THIELE, GEORG; (HANAU,
DE) |
Correspondence
Address: |
SMITH GAMBRELL & RUSSELL LLP
BEVERIDGE DEGRANDI WEILACHER & YOUNG
INTELLECTUAL PROPERTY GROUP
1850 M STREET N W SUITE 800
WASHINGTON
DC
20036
|
Assignee: |
Steffen Hasenzahl
|
Family ID: |
26026690 |
Appl. No.: |
09/293949 |
Filed: |
April 19, 1999 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09293949 |
Apr 19, 1999 |
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08878509 |
Jun 19, 1997 |
|
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5919430 |
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60029676 |
Oct 30, 1996 |
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Current U.S.
Class: |
423/702 ;
423/326; 423/328.2; 423/704; 502/64 |
Current CPC
Class: |
Y10S 423/22 20130101;
C01B 37/00 20130101; C01B 37/005 20130101; C01B 39/12 20130101;
B01J 29/86 20130101; C01B 39/065 20130101; B01J 29/04 20130101;
Y10S 423/27 20130101; Y10S 423/29 20130101; C07D 301/12 20130101;
B01J 29/89 20130101 |
Class at
Publication: |
423/702 ;
423/326; 423/328.2; 423/704; 502/64 |
International
Class: |
C01B 033/36; C01B
039/04 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 30, 1997 |
DE |
196 24 340.8 |
Claims
We claim:
1. A binder-free shaped objected selected from the group consisting
of microporous and mesoporous metal silicates, obtained by the
hydrothermal reaction of a silicon and metal source in the presence
of a template, wherein a pyrogenic metal-silicon mixed oxide is the
silicon and metal source.
2. The binder-free shaped object according to claim 1 wherein the
crystalline microporous and mesoporous metal silicates are
represented by the composition
(SiO.sub.2).sub.1-x(A.sub.mO.sub.n).sub.x (Ia),
(SiO.sub.2).sub.1-x((A.sub.mO.sub.n).sub.1-y(A'.sub.m,O.sub.n,).sub.y).su-
b.x (Ib) or (SiO.sub.2).sub.1-x(M.sub.rA.sub.mO.sub.n,).sub.x (II)
in which x is a number from 0.0001 to 0.25; y is a number greater
than 0 and less than 1; A and A' are a metal of valency p selected
from the group consisting of B, Al, Ga, In, Ge, Sn, Pb, and
subgroups 3 to 8 of the Periodic Table of Elements; M is a cation
of valency q selected from the group consisting of alkali metals,
alkaline earth metals, H.sup.+, NH.sub.4.sup.+and
N(alkyl).sub.4.sup.+ m, m', n, n', n" and r are the number of
atoms, where: m.multidot.p=2n and m'.multidot.p=2n' and
m.multidot.p+r.multidot.q=2n", wherein a pyrogenic mixed oxide of
composition (Ia) or (Ib) is used and the cation M of formula (II)
is incorporated via the template or via alkali metal or alkaline
earth metal hydroxide present in the hydrothermal reaction.
3. The binder-free shaped object according to claim 1 wherein said
pyrogenic metal-silicon mixed oxide is prepared by flame
hydrolysis.
4. The binder-free shaped object according to claim 1 wherein said
pyrogenic mixed oxide is selected from the group consisting of
(SiO.sub.2).sub.1-x(TiO.sub.2).sub.x,
(SiO.sub.2).sub.1-x(Al.sub.2O.sub.3- ).sub.x,
(SiO.sub.2).sub.1-x(B.sub.2O.sub.3).sub.x,
(SiO.sub.2).sub.1-x(V.sub.2O.sub.5).sub.x and (SiO.sub.2).sub.1-x
(ZrO.sub.2).sub.x.
5. The binder-free shaped object according to claim 4 which is
(SiO.sub.2).sub.1-x(TiO.sub.2).sub.x .
6. The binder-shaped object according to claim 1 wherein said
template is an amine having one or more amino groups, an amino
alcohol or a tetrasubstituted ammonium compound.
7. The binder-free shaped object according to claim 1 wherein said
template is used in an amount of 0.05 to 2.0 mol per mol of
SiO.sub.2 in the mixed oxide.
8. The binder-free shaped object according to claim 1 further
comprising carrying out the hydrothermal reaction for the
preparation of microporous metal silicates at a temperature from
100 to 220.degree.C.
9. The binder-free shaped object according to claim 1 further
comprising carrying out the hydrothermal reaction for preparation
of microporous metal silicates at a temperature from 150 to
190.degree.C.
10. The binder-free shaped object according to claim 1 wherein the
preparation of mesoporous metal silicates is carried out at a
temperature from 50 to 175.degree.C. under at least autogenous
pressure.
11. A process for catalytic oxidation reactions, wherein a catalyst
is present corresponding to an Al-free metal silicalite defined in
claim 1.
12. The process according to claim 11 wherein the catalyst is
(SiO.sub.2).sub.1-x(TiO.sub.2).sub.x.
13. A process for the oxidation of an olefin wherein a catalyst is
present, said catalyst being the binder-free shaped object of claim
1.
14. The process according to claim 13 wherein the catalyst is
(SiO.sub.2).sub.1-x(TiO.sub.2).sub.x.
15. The process according to claim 11 wherein propene is oxidized
with hydrogen peroxide to give the corresponding epoxide.
16. The process according to claim 12 wherein propene is oxidized
with hydrogen peroxide to give the corresponding expoxide.
17. A process for preparing a hydroxy aromatic compound comprising
reacting an aromatic compound with hydrogen peroxide or an organic
hydroperoxide in the presence of a binder-free shaped object
according to claim 1.
18. A process for producing an alcohol or ketone comprising
reacting an aliphatic hydrocarbon with hydrogen peroxide or an
organic hydroperoxide in the presence of a binder-free shaped
object according to claim 1.
19. The process according to claim 18, wherein a ketone is
converted to an oxime by reacting with hydrogen peroxide and
ammonia.
20. A process for the catalytic epoxidation of an olefin with
hydrogen peroxide as the oxidant comprising carrying out the
epoxidation in the presence of a catalyst which is a crystalline
microporous titanium silicate of the composition
(SiO.sub.2).sub.1-x(TiO.sub.2).sub.x in which x is a number from
0.001 to 0.2 wherein a pyrogenic silicon-titanium mixed oxide is
reacted with tetraalkylammonium hydroxide template in a
hydrothermal reaction at a temperature from 100 to 220.degree.C.,
and wherein the pyrogenic silicon-titanium mixed oxide is shaped to
microgranules by a spray drying process prior to the hydrothermal
reaction and a crystalline microporous titanium silicate in the
form at microgranules is formed.
21. The process of claim 20, wherein the olefin is propene.
Description
REFERENCE TO A RELATED APPLICATION
[0001] This is a divisional application based on copending
application Ser. No. 08/878,509 filed Jun. 19, 1998 which is relied
on and incorporated herein by reference.
INTRODUCTION AND BACKGROUND
[0002] The present invention relates to a process for the
preparation of crystalline microporous and mesoporous metal
silicates composed of silicon dioxide and one or more metal oxides.
In another aspect, the present invention relates to products
obtainable by said process. Still further, the present invention
relates to the use of these products.
[0003] A variety of crystalline microporous and mesoporous metal
silicates are known. According to the IUPAC definition, micropores
are understood as meaning pores with a diameter of less than 2 nm,
and mesopores are understood as meaning pores with a diameter of 2
to 50 nm. These definitions are used herein.
[0004] Some crystalline metal silicates with regular micropores or
mesopores are extremely effective catalysts in a very wide variety
of applications. In particular, microporous products of the
composition (SiO.sub.2).sub.1-x(TiO.sub.2).sub.x, in which titanium
atoms replace some of the silicon atoms in the crystal lattice,
have achieved industrial importance as oxidation catalysts. The
structures of these metal silicates differ according to the
starting materials and conditions of preparation. Thus, for
example, so-called titanium silicalite-1, titanium silicalite-2 and
titanium beta-zeolite have the MFI, MEL and BEA crystal structures,
respectively. Crystal structure types of known zeolites and
silicalites are described in W. M. Meier, D. H. Olson, Atlas of
Zeolite Structure Types, Butterworth-Heinemann, 1993. Known
structures with regular mesopores are the MCM-41 and MCM-48
structures described in C. T. Kresge et al., Nature, 359 (1992),
pp. 710-712. A survey of structures with regular mesopores is also
given in S. Behrens, Angew, Chemie, 1996, 108 (5), pp. 561-564.
[0005] It is known that the catalytic efficacy of generic metal
silicates is substantially dependent on their phase purity and the
morphology and, hence, on the conditions of preparation. For
example, the catalytic activity of titanium silicalite is reduced
by other titanium-containing phases, for instance TiO.sub.2, and by
an increase in the crystal size; see, B. Notari in (a) Catal. Today
18 (1993), p. 163 and (b) Stud. Surf. Sci. Catal., 67 (1991), p.
243.
[0006] Generic metal silicates, for instance titanium silicalite-1,
can be prepared by hydrothermal synthesis. In the first step, a
silicon source and a titanium source, conventionally tetraalkyl
orthosilicate and tetraalkyl orthotitanate, and water are condensed
to a gel in the presence of a structure-determining quaternary
ammonium cation, usually used in the form of the quaternary
ammonium hydroxide, and the gel is then crystallized under
hydrothermal conditions, usually above 100.degree.C. and under
autogenous pressure. The solid formed is separated off, washed,
dried and calcined above 300.degree.C. The way in which the Ti
component is introduced is liable to cause problems, it often being
impossible to exclude contamination of the product by TiO.sub.2 as
a foreign phase--loc. cit. B. Notari (b). According to EP 543 247,
the quaternary ammonium hydroxide can be replaced as the template
with a combination of a quaternary ammonium salt and a base such as
ammonia, although the crystals obtained are relatively large.
According to U.S. Pat. No. 5,198,203 a mesoporous titanium silicate
of the MCM-41 structure can be prepared with cetyltrimethylammonium
hydroxide as the template.
[0007] Another known silicon source is pyrogenic silicic acid.
According to R. Kumar et al. in Stud. Surf. Sci. Catal., 84 (1994)
p. 109, titanium silicalite-1 can be obtained by hydrothermal
synthesis from pyrogenic silicic acid and tetrabutyl orthotitanate.
The use of a tetraalkyl orthotitanate carries the risk of obtaining
a product of insufficient phase purity.
[0008] According to EP 0 311 983, titanium silicalites are prepared
by impregnating a coprecipitated porous TiO.sub.2--SiO.sub.2
material, which can be amorphous or crystalline, with a template
compound and then subjecting the product to hydrothermal synthesis.
Suggestions of using coprecipitates with other metals, or pyrogenic
mixed oxides, are not to be found in said document.
[0009] In known synthesis processes the generic microporous metal
silicates are formed as crystallites with a size usually of less
than one micrometer, which can only be separated from a liquid at
considerable expenses. For many industrial applications the fine
material is therefore coarsened by a subsequent agglomeration step.
According to EP 0 265 018, the agglomeration is effected using
oligomeric SiO.sub.2 as a binder.
[0010] According to EP 0 299 430, a preformed amorphus SiO.sub.2
matrix is impregnated with an aqueous solution containing a soluble
titanium compound and a suitable template, and crystallized under
hydrothermal conditions, the shape and size of the SiO.sub.2 matrix
remaining essentially unchanged. This process again has the
disadvantage that the use of a soluble titanium compound carries
the risk of reducing the phase purity and hence the catalytic
activity.
[0011] Accordingly, it is an object of the invention to produce
generic metal silicates of high phase purity and high catalytic
activity.
[0012] Another object of the invention is to provide a process
suitable not only for the preparation of products based on
(SiO.sub.2).sub.1-x(TiO- .sub.2).sub.x, but also for the
preparation of products in which titanium is replaced with one or
more other metals in the crystal lattice.
[0013] Still further, another object of the invention is to carry
out the process in such a way that binder-free shaped objects of
the crystalline microporous and mesoporous metal silicates can be
obtained directly, i.e., without a subsequent agglomeration
step.
SUMMARY OF THE INVENTION
[0014] In achieving the above and other objects, a feature of the
invention resides in a process for the preparation of microporous
and mesoporous metal silicates, comprising the hydrothermal
reaction of a silicon source in the presence of a metal source and
a template wherein a pyrogenic metal-silicon mixed oxide is used as
the silicon and metal source. Any suitable template can be used for
purposes of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0015] The general composition of the pyrogenic mixed oxides and
hence also of the crystalline microporous and mesoporous metal
silicates to be prepared is represented as follows:
(SiO.sub.2).sub.1-x(A.sub.mO.sub.n).sub.x (Ia),
(SiO.sub.2).sub.1-x((A.s-
ub.mO.sub.n).sub.1-y(A'.sub.m,O.sub.n,).sub.y).sub.x (Ib).
[0016] In the above formulae, A and A' are each the same or
different metal of valency p selected from the group consisting
of:
[0017] B, Al, Ga, In, Ge, Sn and Pb or from subgroups 3 to 8 of the
Periodic Table of Elements;
[0018] m and m' and n and n' are the number of atoms, where
m.multidot.p=2n and m'.multidot.p=2n';
[0019] x is a number from 0.0001 to 0.25, preferably from 0.001 to
0.2 and especially from 0.005 to 0.1; and
[0020] y in formula (Ib) is a number greater than 0 and less than
1.
[0021] Apart from SiO.sub.2, pyrogenic mixed oxides which are
preferably to be used contain one or more oxides selected from the
group consisting of Al.sub.2O.sub.3, B.sub.2O.sub.3, TiO.sub.2,
ZrO.sub.2, V.sub.2O.sub.5, Cr.sub.2O.sub.3 and Fe.sub.2O.sub.3.
Oxides of the subgroup elements are optionally present not only in
the highest oxidation state but also in a lower oxidation state.
Generic metal silicates which are to be used as oxidation catalysts
are prepared with mixed oxides which are free of aluminum oxide,
the process according to the invention giving metal silicalites in
this case. Generic metal silicates of the composition
(SiO.sub.2).sub.1-x(M.sub.rA.sub.mO.sub.n,) (II)
[0022] are prepared using mixed oxides of composition (Ia). M in
composition (II) is a cation of valency q selected from the group
consisting of alkali metals, alkaline earth metals, H.sup.+,
NH.sub.4.sup.+and N(alkyl).sub.4.sup.+;
m.multidot.p+r.multidot.q=2n" in (II). In the process according to
the invention, M is introduced into the metal silicate either via
the template or via alkali metal or alkaline earth metal hydroxide
or ammonia present in the hydrothermal synthesis. After the
calcination of a generic metal silicate of composition (II), M is a
proton or an alkali metal or alkaline earth metal ion. However,
said cations M or other cations can also be incorporated into the
microporous and mesoporous metal silicates at a later stage by
means of conventional ion exchange reactions.
[0023] The pyrogenic mixed oxides to be used in the process
according to the invention can be prepared in a manner known per se
from a mixture of a volatile silicon compound and one or more
volatile metal compounds (compounds of A and/or A'), for example,
by flame hydrolysis or the luminous arc process. The process
according to the invention is preferably carried out using
pyrogenic mixed oxides of silicon which have been prepared by flame
hydrolysis, for example, those known from Ullmann's Encyklopdie der
Technischen Chemie (Ullmann's Encyclopedia of Chemical Technology),
4th edition, vol. 21, pp. 464-465 (1982) and DE-A 36 11 449.
[0024] The process according to the invention can be carried out
using both the pulverulent pyrogenic mixed oxides and shaped
objects thereof.
[0025] The shaped objects of the metal-silicon mixed oxide can be
produced by known processes, for example, spray granulation,
fluidized bed granulation, extrusion, pelleting or tableting. In a
preferred embodiment of the invention the shaped objects can be
produced by means of spray granulation, as described, for example,
in DE-A 36 11 449.
[0026] In the process according to the invention the pyrogenic
metal/silicon mixed oxide, in powder form or in the form of a
binder-free shaped object produced therefrom, is brought into
contact with an aqueous solution of a suitable template; when using
coarser shaped objects of mixed oxide, for instance extrudates,
this is conventionally an impregnation process. After intermediate
drying, if appropriate, this step is followed by the hydrothermal
reaction to convert the pyrogenic metal-silicon mixed oxide to the
crystalline microporous or mesoporous metal silicate according to
the invention. After the hydrothermal reaction, the template is
removed from the metal silicate in a manner known, per se,
conventionally by extraction or, preferably by calcination.
[0027] Suitable template compounds are amines having one or more
amino groups, amino alcohols or tetrasubstituted ammonium
compounds. Tetraalkylammonium compounds are particularly suitable,
especially tetraalkylammonium hydroxide. The nature of the alkyl
groups in said tetraalkylammonium compounds is significant in terms
of the pore structure. The tetraalkylammonium compounds used to
prepare microporous metal silicates according to the invention are
preferably those in which alkyl is ethyl, propyl and butyl,
preferably n-propyl. Thus, for example, metal silicates according
to the invention of the MFI, MEL and BEA structure can be prepared
using tetra-n-propylammonium, tetra-n-butylammonium and
tetraalkylammonium compounds, respectively. The tetraalkylammonium
compounds used to prepare mesoporous metal silicates according to
the invention are preferably those which have surfactant
properties. Accordingly, these compounds contain an alkyl group or
an alkenyl group having at least 7 C atoms in the longest chain.
Particularly preferred ammonium compounds are those of the general
formula RNR'.sub.3.sup.+X.sup.-, in which R contains 12 to 18 C
atoms and is preferably unbranched and saturated, R' has 1 or 2 C
atoms, and X is the anion, conventionally hydroxide or halide.
Cetyltrimethylammonium chloride or bromide and
lauryltrimethylammonium chloride or bromide are particularly
suitable for the preparation of mesoporous structures. When using
tetraalkylammonium halides as the template, a base, such as
ammonia, a primary, secondary or tertiary amine or an alkali metal
or alkaline earth metal hydroxide, is added to the template
solution used for the contacting/impregnation process. The template
compound is conventionally used in a molar ratio of template to
SiO.sub.2 of 0.05 to 2.0. For the preparation of microporous metal
silicates, a molar ratio template to SiO.sub.2 of from 0.05 to 1.0,
especially from 0.10 to 0.45, is preferred. For the preparation of
mesoporous metal silicates according to the invention of the MCM-41
or MCM-48 structure, a molar ratio of template to SiO.sub.2 of from
0.05 to 2.0, especially of from 0.1 to 0.8, is preferred.
[0028] The molar ratio OH/SiO.sub.2 is generally from 0.05 to 2.0
and preferably from 0.1 to 1.0. In the hydrothermal reaction to the
molar ratio H.sub.2O/SiO.sub.2 is from 1 to 200 and preferably from
4 to 100. Seed crystals of the same structural type can be added to
the reaction mixture if necessary. The molar ratio
H.sub.2O/SiO.sub.2 is generally lower when using shaped objects of
pyrogenic mixed oxides than when using pyrogenic mixed oxides as
obtained directly by flame hydrolysis.
[0029] In the process according to the invention for the
preparation of microporous metal silicates, the hydrothermal
reaction is conventionally carried out under autogenous pressure at
a temperature from 100 to 200.degree.C. and preferably from 150 to
190.degree.C. Mesoporous metal silicates according to the invention
can also be prepared at lower temperature, the conventional
temperature range being from 25 to 200.degree.C., preferably from
50 to 175.degree.C. and especially from 70 to 150.degree.C. The
hydrothermal reaction is carried out until the pyrogenic mixed
oxide used has been completely converted to the crystalline
microporous or mesoporous metal silicate according to the invention
at the given reaction temperature. The degree of completion of the
reaction can be determined by known methods of structural analysis.
Under optimized conditions the reaction time is conventionally from
1 to 50 hours.
[0030] To remove the template compound from the solid obtained in
the hydrothermal reaction, said solid is usually calcined at from
300 to 1000.degree.C., optionally after a prior washing process, it
being possible for the calcination step to include a shaping
process at the same time. In the case of the mesoporous metal
silicates according to the invention, at least some of the template
compound can also be removed by extraction with an organic
solvent.
[0031] In one particular embodiment of the process according to the
invention, the pyrogenic metal-silicon mixed oxide, for instance as
obtained by flame hydrolysis, is suspended in an aqueous template
solution. The molar ratios used here can be the same as those
indicated above. This suspension is spray-dried, and the resulting
granules containing the template are treated in an autoclave at
elevated temperature, for example, at 175.degree.C., optionally in
a steam atmosphere. The spray drying is advantageously carried out
by setting the temperature of the drying air in the range of 100 to
500.degree.C. so that the resulting granules have a water content
of 5 to 50 wt. %. After the hydrothermal reaction, the shaped
objects obtained are calcined at a temperature of 300 to
1000.degree.C., preferably of 400 to 800.degree.C., to remove the
template.
[0032] The process according to the invention can be carried out
reproducibly and is easy to control. The use of the pyrogenic mixed
oxides avoids problems due to the presence of foreign phases of the
metal oxides in question. A high catalytic activity is a
characteristic feature of the crystalline microporous and
mesoporous metal silicates obtainable by the process according to
the invention. The generic metal silicates can moreover be obtained
not only in the form of very finely powdered materials but also in
the form of different shaped objects. When using shaped objects of
pyrogenic mixed oxides or forming such shaped objects directly
before the hydrothermal reaction, a subsequent agglomeration step
is not necessary. The addition of catalytically inactive binders is
also superfluous.
[0033] A further advantage of shaped objects of crystalline
microporous and mesoporous metal silicates obtainable according to
the invention is that they can be separated more easily from
liquids filtration than unshaped catalysts, thereby facilitating
their use as suspension catalysts. As pyrogenic mixed oxides are
easy to shape, for instance into spheres, extrudates, pellets or
tablets and the shape remains essentially unchanged in the process
according to the invention, said process directly produces suitable
shaped objects for use as catalysts in fixed bed reactions.
[0034] Although it is know from EP 0 311 983 B that coprecipitated
TiO.sub.2--SiO.sub.2 material can be used for the preparation of
titanium silicates, the copreciptates to be used are very porous
products. It was therefore surprising that crystalline microporous
and mesoporous metal silicates are easily obtainable by using
pore-free pyrogenic mixed oxides such as those used in the process
according to the invention.
[0035] As such, preferably in the form of shaped objects, the
crystalline microporous and mesoporous metal silicates obtainable
according to the invention are used as catalysts. Titanium
silicalites and other aluminum-free products are particularly
suitable as catalysts for oxidation reactions with hydrogen
peroxide or organic hydroperoxides. Examples are the use of
titanium silicalite-1 as a catalyst for the reaction of olefins,
i.e., propene, with hydrogen peroxide to give epoxides (EP 100
119), the reaction of aromatics with hydrogen peroxide to give
hydroxyaromatics (DE 31 35 559), the reaction of aliphatic
hydrocarbons with hydrogen peroxide to give alcohols and ketones
(EP 376 453) and the reaction of cyclohexanone with hydrogen
peroxide and ammonia to give cyclohexanone oxime (EP 208 311).
Titanium silicalite-2 is used as a catalyst for the hydroxylation
of phenol (J. S. Reddy, S. Sivasanker, P. Ratnasamy, J. Mol. Catal.
71 (1992) p. 373) and for the reaction of cyclohexanone with
hydrogen peroxide and ammonia to give cyclohexanone oxime (J. S.
Reddy, Reddy, S. Sivasanker, P. Ratnasamy, J. Mol. Catal. 71 (1992)
p. 383) . Titanium beta-zeolite can be used as a catalyst for the
reaction of olefins with hydrogen peroxide or organic
hydroperoxides to give epoxides (A. Corma, P. Esteve, A. Martinez,
S. Valencia, J. Catal. 152 (1995) p. 18 and EP 659 685).
[0036] The following examples serve to illustrate the present
invention.
EXAMPLE 1
[0037] Preparation of Titanium Silicalite-1 Powder
[0038] 137.0 g of tetrapropylammonium hydroxide solution (40 wt. %)
and 434.2 g of deionized water are placed in a polyethylene beaker
and 111.1 g of pyrogenic silicon-titanium mixed oxide containing
3.0 wt. % of TiO.sub.2 are added, with stirring. The resulting
synthetsis gel is first aged for four hours at 80.degree.C., with
stirring, and then crystallized in an autoclave for 24 hours at
175.degree.C. The solid obtained is separated from the mother
liquor by centrifugation, washed with three times 250 ml of
deionized water, dried at 90.degree.C. and calcined in an air
atmosphere for four hours at 550.degree.C. The yield is 98.3 g.
[0039] The X-ray diffraction diagram of the catalyst prepared in
this way shows the diffraction pattern typical of the MFI
structure, and the IR spectrum shows the band at 960 cm.sup.-1
characteristic of titanium-containing molecular sieves. Wet
chemical analysis gives a titanium content of 2.3 wt. % of
TiO.sub.2. The DR-UV-Vis spectrum also shows that the sample is
free of titanium dioxide.
EXAMPLE 2
[0040] Application Example of the Epoxidation of Propylene With
Hydrogen Peroxide
[0041] 1.0 g of the catalyst prepared according to Example 1 in 300
ml of the methanol is placed in a thermostated laboratory autoclave
with gas dispersion stirrer, at 40.degree.C. under a propylene
atmosphere, and the solvent is saturated with propylene under an
excess pressure of 3 bar. 13.1 g of 30 wt. % aqueous hydrogen
peroxide solution is then added all at once, with stirring, and the
reaction mixture is kept at 40.degree.C. and 3 bar, additional
propylene being metered in via a pressure regulator in order to
make up the quantity consumed by the reaction. Samples are taken at
regular intervals via a filter, and hydrogen peroxide content of
the reaction mixture is determined by redox titration with cerium
(IV) sulphate solution. The plot of 1n(c/c.sub.0) against the time
t, c being the measured H.sub.2O.sub.2 concentration at time t and
c.sub.0 being the calculated H.sub.2O.sub.2 concentration at the
start of the reaction, gives a straight line. An activity
coefficient k of 25.4 min.sup.-1 is determined from the gradient of
the lines by means of the relationship
dc/dt=-k.multidot.c.multidot.c.sub.cat, where c.sub.cat is the
catalyst concentration in kg of catalyst per kg of reaction
mixture.
EXAMPLE 3
[0042] Preparation of Titanium Silicalite-1 Microgranules
[0043] 800 g of deionized water and 30 g of acetic acid are placed
in a polyethylene beaker and 200 g of pyrogenic silicon-titanium
mixed oxide containing 3.6 wt. % of TiO.sub.2 are added, with
stirring. This mixture is sheared for five minutes in an Ultraturax
stirrer. The resulting suspension is dried by means of a spray
dryer (NIRO-Atomizer model 1638; inlet temperature 380.degree.C.;
outlet temperature 102.degree.C.; speed of rotation of the spray
disk 15,000 min.sup.-1). 20 g of the resulting microgranules, with
a mean particle diameter of 30 .mu.m, are impregnated with a
mixture of 20 g of tetrapropylammonium hydroxide solution (40 wt.
%) and 20 g of deionized water. The impregnated microgranules are
charged into an autoclave with a Teflon inliner and crystallized
for 24 hours at 175.degree.C. under static conditions. The solid
obtained is separated from the mother liquor by centrifugation,
washed three times with 100 ml of deionized water, dried at
90.degree.C. and calcined in an air atmosphere for four hours at
550.degree.C. The yield is 17 g.
[0044] The catalyst prepared in this way consists of titanium
silicalite-1 microgranules.
EXAMPLE 4
[0045] Preparation of Titanium Silicalite-1 Microgranules
[0046] 720.7 g of deionized water and 179.3 g of
tetrapropylammonium hydroxide solution (40 wt. %) are placed in a
polyethylene beaker and 100 g of pyrogenic silicon-titanium mixed
oxide containing 3.6 wt. % of TiO.sub.2 are added, with stirring.
This mixture is sheared for five minutes in an Ultraturax stirrer.
The resulting suspension is dried by means of a spray dryer
(NIRO-Atomizer model 1638; inlet temperature 380.degree.C.; outlet
temperature 90.degree. C.; speed of rotation of the spray disk
15,000 min.sup.-1). 20 g of the resulting microgranules, with a
mean particle diameter of 30 .mu.m, a loss on drying of 23 wt. %
(10 h at 105.degree.C.; corresponds to the water content) and a
loss on calcination of 43 wt. % (5 h at 550.degree.C.; corresponds
to the water and template content), are charged into an autoclave
with a Teflon inliner and crystallized for 4 days at 180.degree.C.
under static conditions. The solid is then dried at 90.degree.C.
and calcined in an air atmosphere for four hours at
550.degree.C.
[0047] The catalyst prepared in this way consists of titanium
silicalite-1 microgranules.
EXAMPLE 5
[0048] Preparation of a Titanium Beta-Zeolite Powder
[0049] 435.3 g of tetraethylammonium hydroxide solution (35 wt. %)
and 236.3 g of deionized water are placed in a polyethylene beaker
and 109.6 g of pyrogenic silicon-titanium mixed oxide containing
3.0 wt. % of TiO.sub.2 is added. The resulting mixture is aged for
four hours at 80.degree. C. and, after cooling to room temperature,
12 g of beta-zeolite seed crystals with an
SiO.sub.2/Al.sub.2O.sub.3 ratio of 27 are added. This synthesis gel
is crystallized in an autoclave for 3 days at 150.degree.C., with
stirring.
[0050] The solid obtained is separated from the mother liquor by
centrifugation, washed three times, each time with 250 ml of
deionized water, dried at 90.degree.C. and calcined in an air
atmosphere for four hours at 550.degree.C.
[0051] The X-ray diffraction diagram of the catalyst prepared in
this way shows the diffraction pattern typical of the BEA
structure. Wet chemical analysis gives a titanium content of 1.8
wt. % of TiO.sub.2.
EXAMPLE 6
[0052] Preparation of a Mesoporous Titanium Silicate of the MCM-41
Structure
[0053] 114.2 of tetramethylammonium hydroxide solution (10% wt. %)
is placed in a polyethylene beaker and 30.0 g of pyrogenic
silicon-titanium mixed oxide containing 3.6 wt. % of TiO.sub.2 are
added, with stirring. This mixture is stirred for one hour. A
suspension of 29.1 g of cetyltrimethylammonium bromide
(C.sub.16H.sub.33(CH.sub.3).sub.3NBr) in 109.2 g of deionized water
is then added, with stirring, and stirring is continued for 10
minutes. The resulting synthesis gel (molar composition: SiO.sub.2:
0.17 C.sub.16H.sub.33(CH.sub.3).sub.3N.sup.+:0.26 Me.sub.4NOH:25
H.sub.2O) is crystallized in an autoclave for 48 hours at
140.degree.C. under static conditions. The solid obtained is
filtered off and washed with deionized water until the filtrate is
neutral. The solid is dried at 90.degree.C. and then calcined in an
air atmosphere for four hours at 640.degree.C. The yield is 28
g.
[0054] The X-ray diffraction diagram of the catalyst prepared in
this way shows the diffraction pattern typical of the MCM-41
materials, with d.sub.100 reflection at 3.60 nm. Examination by
sorption analysis with nitrogen at 77 K shows a mean pore diameter
of 3.16 nm, a BET specific surface area of 1040 m.sup.2 g.sup.-1
and a pore volume of 0.89 ml/g. Wet chemical analysis gives a
titanium content of 4.6 wt. % of TiO.sub.2. The material is
catalytically active in the epoxidation of propene with hydrogen
peroxide.
EXAMPLE 7
[0055] Preparation of a Mesoporous Titanium Silicate of the MCM-48
Structure
[0056] 114.2 g of tetramethylammonium hydroxide solution (10% wt.
%) is placed in a polyethylene beaker and 30.0 g of pyrogenic
silicon-titanium mixed oxide containing 3.6 wt. % of TiO.sub.2 are
added, with stirring. This mixture is stirred for one hour. A
suspension of 114.2 g of cetyltrimethylammonium bromide
(C.sub.16H.sub.33(CH.sub.3).sub.3NBr) in 435.2 g of deionized water
is then added, with stirring, and stirring is continued for 10
minutes. The resulting synthesis gel (molar composition:
SiO.sub.2:0.65 C.sub.16H.sub.33(CH.sub.3).sub.3NBr:0.26 Me.sub.4NOH
:62 H.sub.2O) is crystallized in an autoclave for 48 hours at
140.degree.C. under static conditions. The solid obtained is
filtered off and washed with deionized water until the filtrate is
neutral. The solid is dried at 90.degree.C. and then calcined in an
air atmosphere for four hours at 640.degree.C.
[0057] The catalyst prepared in this way consists of Ti-MCM-48.
EXAMPLE 8
[0058] Preparation of a Boron Pentasil Zeolite
[0059] 800 g of aqueous hexamethylenediamine solution (50 wt. %) is
placed in a polyethylene beaker and 70.7 g of pyrogenic
silicon-boron mixed oxide containing 9.5 wt. % of B.sub.2O.sub.3 is
added, with stirring. This mixture is stirred for half an hour and
then crystallized in an autoclave for five days at 170.degree.C.
The solid obtained is separated from the mother liquor by
centrifugation, washed three times in 250 ml of deionized water,
dried at 90.degree.C. and calcined in an air atmosphere for six
hours at 550.degree.C.
[0060] The X-ray diffraction diagram of the catalyst prepared in
this way shows the diffraction pattern typical of the MFI
structure. Wet chemical analysis gives a B.sub.2O.sub.3 content of
2.4 wt. %.
EXAMPLE 9
[0061] Preparation of a Boron Silicate of the MCM-41 Structure
[0062] 156.7 g of tetramethylammonium hydroxide solution (10 wt. %)
is placed in a polyethylene beaker and 42.3 g of pyrogenic
silicon-boron mixed oxide containing 5.5 wt. % of B.sub.2O.sub.3 is
added, with stirring. This mixture is stirred for one hour. A
suspension of 65.5 g of cetyltrimethylammonium bromide
(C.sub.16H.sub.33(CH.sub.3).sub.3NBr) in 576.5 g of deionized water
is then added, with stirring, and stirring is continued for 10
minutes. The pH is adjusted to 11.5 by the addition of dilute
sulphuric acid. The resulting synthesis gel is crystallized in an
autoclave for 48 hours at 140.degree.C. under static conditions.
The solid obtained is filtered off and washed with deionized water
until the filtrate is neutral. The solid is dried to 90.degree.C.
and then calcined in an air atmosphere for four hours at
540.degree.C.
[0063] The X-ray diffraction diagram of the catalyst obtained shows
the diffraction pattern typical of the MCM-41 materials.
Examination by sorption analysis with nitrogen at 77.degree.K.
shows a mean pore diameter of 2.83 nm, a BET specific surface area
of 1060 m.sup.2 /g and a pore volume of 0.89 ml/g.
EXAMPLE 10
[0064] Preparation of a Zirconium Silicalite-1 Powder
[0065] 62.4 g of tetrapropylammonium hydroxide solution (40 wt. %)
and 229.8 g of deionized water are placed in a polyethylene beaker
and 57.4 g of pyrogenic silicon-zirconium oxide containing 3.0 wt.
% of ZrO.sub.2 are added, with stirring. The resulting synthesis
gel is then crystallized in an autoclave for 24 hours at
175.degree.C. The solid obtained is separated from the mother
liquor by centrifugation, washed with three times 250 ml of
deionized water, dried at 90.degree.C. and calcined in an air
atmosphere for four hours at 550.degree.C.
[0066] The X-ray diffraction diagram of the catalyst obtained shows
the diffraction pattern typical of the MFI structure. X-ray
fluorescence analysis gives ZrO.sub.2 content of 1.0 wt. %
EXAMPLE 11
[0067] Preparation of a Zirconium Silicate of the MCM-41
Structure
[0068] 114.2 g of tetramethylammonium hydroxide solution (10 wt. %)
are placed in a polyethylene beaker and 30.0 g of pyrogenic
silicon-zirconium oxide containing 3.0 wt. % of ZrO.sub.2 is added,
with stirring. This mixture is stirred for one hour. A suspension
of 29.1 g of cetyltrimethylammonium bromide
(C.sub.16H.sub.33(CH.sub.3).sub.3NBr) in 109.2 g of deionized water
is then added, with stirring, and stirring is continued for 10
minutes. The resulting synthesis gel is crystallized in an
autoclave for 48 hours at 140.degree.C. under static conditions.
The solid obtained is filtered off and washed with deionized water
until the filtrate is neutral. The solid is dried to 90.degree.C.
and then calcined in an air atmosphere for four hours at
640.degree.C.
[0069] The X-ray diffraction diagram of the catalyst obtained shows
the diffraction pattern typical of the MCM-41 materials with a
d.sub.100 value of 3.25 nm. Examination by sorption analysis with
nitrogen at 77 K shows a mean pore diameter of 2.4 nm, a BET
specific surface area of 860 m.sup.2/g and a pore volume of 0.59
ml/g.
[0070] Further variations and modifications of the foregoing will
be apparent to those skilled in the art and intended to be
encompassed by the claims appended hereto.
[0071] German priority application 196 24 340.8 is relied on and
incorporated hereby reference.
* * * * *