CA2314233A1

CA2314233A1 - Shaped body comprising an inert support and at least one porous oxidic material

Info

Publication number: CA2314233A1
Application number: CA002314233A
Authority: CA
Inventors: Georg Heinrich Grosch; Ulrich Muller; Andreas Walch; Norbert Rieber; Wolfgang Harder
Original assignee: Individual
Current assignee: BASF SE
Priority date: 1997-12-10
Filing date: 1998-11-25
Publication date: 1999-06-17
Also published as: JP2001525248A; ZA9811261B; DE19754924A1; EP1039969A1; CN1284899A; WO1999029426A1; KR20010032966A; ID25488A; AU1964099A

Abstract

The invention relates to a moulded body comprising an inert support and at least one porous oxidic material applied to said support. The inventive moulded body is obtained by applying a mixture containing the at least one porous oxidic material and at least one metal acid ester or a hydrolyzate thereof or a combination of metal acid esters and hydrolyzate thereof to the inert support.

Description

Shaped body comprising an inert support and at least one porous oxidic material The present invention relates to a shaped body comprising an inert support and at least one porous oxidic material applied thereto, a process for its production, and its use for the conversion of organic compounds, in particular for the epoxidation of organic compounds having at least one C-C double bond. The shaped body described herein has an excellent abrasion resistance and excellent mechanical properties and is cheap compared with catalysts used for these purposes heretofore.
Abrasion-resistant shaped bodies comprising catalytically active materials are employed in many chemical processes, in particular in processes using a fixed bed.
For the production of solids, a binder, an organic viscosity-enhancing compound and a liquid for converting the material into a paste are generally added to the catalytically active material, ie. the porous oxidic material, and the mixture is compacted in a mixing or kneading apparatus or an extruder. The resulting plastically deformable material is then shaped, in particular using an extruder, and the resulting shaped bodies are dried and calcined.
A number of inorganic compounds are used as binders.
For example, according to US-A 5,430,000, titanium dioxide or titanium dioxide hydrate is used as the binder. Examples of further prior-art binders are:
aluminum oxide hydrate or other aluminum-containing binders (WO 94/29408);
mixtures of silicon and aluminum compounds (WO 94/13584);
silicon compounds (EP-A 0 592 050);
clay minerals (JP-A 03 037 156);
alkoxysilanes (EP-B 0 102 544).
Further relevant prior art is reviewed in DE 197 23 751.7.
In conversions exhibiting very high intrinsic reaction rates, the yield that can be achieved technically is limited by the diffusion of the starting materials or products in the shaped body. In these cases, only the surface layer of the shaped body is utilized for conversion, whereas the rest of the shaped body is only the support for this surface layer. It will be appreciated that this is economically prohibitive in the case of an expensive catalytically active material.
Therefore, a supported or coated catalyst in the form of a shaped body is rather used in this case. This catalyst comprises an inert core and a surface layer of catalytically active material.
Catalysts of this type are also prepared using zeolites as active components. For instance, JP 07,241,471 describes the application of zeolite powder to a support by suspending the zeolite in combination with an inorganic binder in water and organic emulsifiers and subsequent wash-coating onto the support. These catalysts are intended for waste gas purification. A
similar procedure is described in JP 07,155,613, where zeolites and silica sol are suspended in water to form a wash coat suspension which is applied to a monolithic cordierite support. Likewise, JP 02,111,438 describes the application of zeolites to- monolithic supports utilizing aluminium sol as a binder. This catalyst is used for waste gas purification, too. US 4,692,423 describes the application of zeolites to porous supports by first admixing the zeolite with cyclic oxides which are,instable with respect to polymerization, coating the surface of the porous support with this suspension and subsequently removing the solvent. US 4,283,583 describes catalysts where a zeolite has been supported on spherical supports of from 0.5 to 10 mm in diameter.
It is true that the adhesion of the active component on the support is important for gas phase processes such as waste gas purification, but the forces acting on the supported layer in a gas phase process are much less abrasive than in a liquid phase process, for example. In the latter case, there are much higher requirements on the adhesion of the supported layer. The anchoring of active material on the inert carrier may be destabilized especially by the permanent presence of liquid or solvent. JP 08,103,659 describes a use for a liquid phase process. There, titanium silicalite is applied to spheres of from 0.2 to 20 mm in diameter. To this end, titanium silicalite is suspended in an aqueous polyvinylalcohol solution and sprayed onto the sphere.
The sprayed sphere is then calcined to give the ready-to-use catalyst which is then used in the epoxidation of propylene with hydrogen peroxide. However, the catalyst generated in this way still exhibits significant abrasion of the active component.
US 5,523,426 describes a way to epoxidize propylene over titanium silicalite catalysts where the titanium silicalite may be applied onto inert carriers, inter alia. The application procedure is not described in detail.

As can be seen from the prior ar't, there is the problem that the catalysts used heretofore are not suitable for use as abrasion-resistant supported catalysts since the adhesion of the active component is usually insufficient for this purpose. Furthermore, a limitation to spherical support bodies is often not sensible for fluid dynamics reasons.
It is thus an object of the present invention to develop a process which makes it possible to apply a zeolite and in particular titanium silicalite to supports of any shape, preferably non-monolithic supports, in an abrasion-resistant manner to give catalysts which may be used in chemical processes, in particular in liquid phase processes, and to provide such a catalyst per se.
We have now found, surprisingly, that this object is achieved by applying a mixture comprising at least one porous oxidic material and at least one metal acid ester or a hydrolysate thereof or a combinat~.on of metal acid ester and hydrolysate on an inert support to give a shaped body which may be used in liquid phase processes without problems.
Accordingly, the present invention provides a shaped body comprising an inert support and at least one porous oxidic material applied thereto and obtainable by applying a mixture comprising at least one porous oxidic material and at least one metal acid ester or a hydrolysate thereof or a combination of metal acid ester and hydrolysate thereof to the inert support, and a process for preparing such a shaped body, which comprises applying a mixture comprising at least one porous oxidic material and at least one metal acid ester or a hydrolysate thereof or a combination of metal acid ester and hydrolysate thereof to an inert support.

The inert supports which may be' used according to the invention may consist of oxides, carbides, nitrides or other inorganic or organic materials, provided that they do not decompose, melt or become otherwise instable at the temperatures required in the preparation process.
For the purposes of the present invention, "inert" means that the materials used as support have negligible catalytic activity, if any.
Preferred inert supports used are metal oxides or mixed oxides of metals of transition groups III to VIII and main groups III to V of the Periodic Table of the Elements and combinations of two or more thereof, in particular silicon dioxide, aluminum oxide, titanium dioxide, zirconium dioxide and mixed oxides thereof.
It is further possible to use metals or metal alloys, such as steel, Kanthal, aluminum, etc., as materials for the inert support.
The inert support preferably has an alkali metal or alkaline earth metal content of < 1,000 ppm, preferably < 100 ppm, in particular < 10 ppm. The low alkali metal or alkaline earth metal contents of the support are of particular importance when the catalyst of the invention is used for epoxidation, especially with a titanium silicalite as porous oxidic material.
The external form of the inert support or shaped body is not critical and can be selected without restriction depending on the fluid dynamics of the particular reactor chosen for the reaction. The inert support or shaped body may be in the form of extrudates, such as circular extrudates, star-shaped extrudates, hollow extrudates and cylinders, granules, tablets, annular tablets, spherical, non-spherical or spherolithic granules, as a monolith or in the form of a band-like structure or a structure having holes, eg. in the form of a mesh or fabric, in pyramidal form or as a waggon wheel profile.
The support or shaped body is preferably in the form of a non-spherical pellet, an extrudate, a granule, a tablet, a band-like structure or a structure having holes.
It is also possible to apply the porous oxidic material directly to the reactor wall. In the case of exothermic reactions, this is even beneficial for heat removal.
There are no particular restrictions with regard to the porous oxidic materials which may be used for the production of the novel shaped body, as long as it is possible to prepare a shaped body as described herein starting from these materials and these materials have the necessary catalytic activity.
The porous oxidic material is preferably a zeolite, particularly preferably a titanium-, zirconium-, chromium-, niobium-, iron- or vanadium-containing zeolite, in particular a titanium silicalite.
Zeolites are known to be crystalline aluminosilicates having ordered channel and cage structures which have micropores. The term micropores as used in the present invention corresponds to the definition given in Pure Appl. Chem. 45 (1976), p. 7lff., in particular p. 79, and refers to pores having a diameter of less than 2 nm.
The network of such zeolites is composed of Si09 and A104 tetrahedra which are linked via common oxygen bridges. An overview of the known structures is given, for example, by W.M. Meier and D.H. Olson in "Atlas of Zeolite Structure Types", Elsevier, 4th Edition, London 1996.
_ _ 7 _ Furthermore, there are zeolites which contain nc aluminum and in which some of the Si(IV) has been replaced by titanium as Ti (IV) in the silicate lattice.
Titanium zeolites, in particular those having a crystal structure of the MFI type, and possibilities for their preparation are described, for example, in EP-A 0 311 983 or EP-A 0 405 978. Apart from silicon and titanium, such materials may also contain additional elements, such as aluminum, zirconium, tin, iron, cobalt, nickel, gallium, boron or small amounts of fluorine.
Some or all of the titanium in the zeolites described may be replaced by vanadium, zirconium, chromium, niobium or iron. The molar ratio of titanium and/or vanadium, zirconium, chromium, niobium or iron to the sum of silicon and titanium and/or vanadium, zirconium, chromium, niobium or iron is usually from 0.001:1 to 0.1:1.
Titanium zeolites having the MFI structure are known to be identifiable from a particular pattern in their X-ray diffraction diagrams and, in addition, by a skeletal vibration band in the infrared (IR) at about 960 cm-1, and thus differ from alkali metal titanates or crystalline and amorphous Ti02 phases.
Said titanium, zirconium, chromium, niobium, iron and vanadium zeolites are usually prepared by reacting an aqueous mixture of an Si02 source, of a titanium, zirconium, chromium, niobium, iron or vanadium source, eg. titanium dioxide or an appropriate vanadium oxide, zirconium alcoxide, chromium oxide, niobium oxide or iron oxide, and of a nitrogenous organic base template, eg. tetrapropylammonium hydroxide, with or without added basic compounds, in a pressure vessel at elevated temperature for several hours or~some days, resulting in a crystalline product. The crystalline product is filtered off, washed, dried and baked at high temperature to remove the organic nitrogen base. In the resulting powder, the titanium or zirconium, chromium, niobium, iron and/or vanadium is present at least partly inside the zeolite framework in varying proportions in four-, five- or six-fold coordination. To improve the catalytic characteristics it is also possible to carry out a subsequent treatment by washing repeatedly with a solution of hydrogen peroxide containing sulfuric acid, after which the titanium, zirconium, chromium, niobum, iron or vanadium zeolite powder must be again dried and baked; this can be followed by a treatment with alkali metal compounds in order to convert the zeolite from the H form into the cation form. The resulting titanium, zirconium, chromium, niobium, iron or vanadium zeolite powder is then processed into a shaped body as described below.
Preferred zeolites are titanium, zirconium, chromium, niobium or vanadium zeolites, more preferred zeolites are those having a pentasil zeolite structure, especially the types with X-ray assignment to a BEA, MOR, TON, MTW, FER, MFI, MEL, CHA, ERI, RHO, GIS, BOG, NON, EMT, HEU, KFI, FAU, DDR, MTT, LTL, MAZ, GME, NES, OFF, SGT, EUO, MFS, MCM-22 or MFI/MEL mixed structure.
Zeolites of this type are described, for example, in the above Meier and Olson reference. Also possible for the present invention are titanium-containing zeolites having the structure of UTD-1, CIT-1 or CIT-5. Such zeolites are described, inter alia, in US-A-5 430 000 and WO 94/29408, the relevant contents of which are fully incorporated herein by reference.
Nor are there special restrictions in the pore structure of the shaped bodies of the invention, ie. the shaped _ _ g _ body according to the invention-can have micropores, mesopores, macropores, micro- and mesopores, micro- and macropores or micro-, meso- and macropores, the definition of "mesopores" and "macro ores P " also corresponding to the definition given in the Pure Appl.
Chem; reference given above and referring to pores having a diameter of from > 2 nm to 50 nm or > 50 nm, respectively.
Furthermore, the shaped body of the invention may be a material based on a mesoporous silicon-containing oxide and a silicon-containing xerogel.
Silicon-containing mesoporous oxides which additionally contain Ti, V, Zr, Sn, Cr, Nb or Fe, in particular Ti, V, Zr, Cr, Nb or a mixture of two or more thereof, are particularly preferred.
To obtain a shaped body having the desired abrasion resistance, the porous oxidic material described in detail above is always applied to the inert support in admixture with at least one metal acid ester or a hydrolysate thereof or a combination of at least one metal acid ester and a hydrolysate thereof (hereinafter often referred to as metal acid ester (hydrolysate)).
The metals of the metal acid esters may be selected from main groups III to IV and transition groups III to VI of the Periodic Table of the Elements. It is also possible to use partial hydrolysates thereof.
Particular examples of these are orthosilicates, alkoxysilanes, tetraalkoxytitanates, trialkoxyaluminates, trialkoxyniobates, tetraalkoxyzirconates or a mixture of two or more thereof. However, particularly preferred metal acid esters used in the present invention are tetraalkoxysilanes. Specific examples are tetramethoxysilane, '- tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane and tetrabutoxysilane, the corresponding tetraalkoxytitanium and tetraalkoxyzirconium compounds and trimethoxy-, triethoxy-, tripropoxy-, trisisopropoxy-, tributoxyaluminum or triisobutoxyaluminum, with tetramethoxysilane and tetraethoxysilane being especially preferred.
According to the invention, the content of metal oxide from the metal acid ester or the hydrolysate thereof is preferably up to about 80% by weight, more preferably from about 1 to about 50% by weight, in particular from about 3 to about 30% by weight, based on the amount of porous oxide.
The content of the mixture applied is generally from about 1 to about 80% by weight, preferably from about 1 to about 50% by weight, in particular from about 3 to about 30% by weight, in each case based on the total amount of mixture and inert support.
As can be seen from the above, mixtures of two or more of the abovementioned binders may of course also be employed.
There are no particular restrictions with regard to the application of the mixture to the inert support. The application can be effected by impregnating, spraying or trickling. Some preferred application methods will now be described in more detail.
To apply the at least one porous oxidic material, the latter is suspended in a liquid, in the form of a powder or pellets, and applied. It is also possible to feed the porous oxidic material in the form of a powder or pellets and the liquid required for adhesion of the porous oxidic material on a he inert support simultaneously. The oxidic material to be applied is preferably suspended in the liquid and sprayed onto the support.
In one embodiment, the metal acid ester (hydrolysate) used according to the invention is admixed with the porous oxidic material having the form of a powder or pellets. The resulting mixture is then trickled onto the inert support which is simultaneously sprayed with an adhesion liquid. In this case, preference is given to using the hydrolysates of the metal acid esters.
In another embodiment of the invention, the metal acid ester (hydrolysate) is mixed with the adhesion liquid to give a mixture which is then applied to the inert support simultaneously with the porous oxidic material having the form of a powder or pellets. In another, preferred embodiment, the metal acid ester (hydrolysate) is suspended in the adhesion-promoting liquid together with the porous oxidic material to give a suspension which is sprayed onto the inert support.
The alcohol used in the above mixture preferably corresponds to the alcohol component of the metal acid ester used or hydrolysate thereof, but it is also not critical to use another alcohol.
A particularly quick adhesion of the mixture can be achieved by impregnating the inert support with acidic substances, such as organic or inorganic acids, eg.
nitric acid, sulfuric acid, hydrochloric acid, acetic acid, oxalic acid or phosphoric acid.
The mixture to be applied to the inert support may contain further additives, such as organic viscosity-enhancing substances and others as defined below.

Adhesion-promoting liquids include water, various organic liquid classes, such as alcohols, diols, polyols, ketones, acids, amines, hydrocarbons and mixtures of two or more thereof. If these liquids are used to suspend the porous oxidic material, preference is given to using liquids volatilizable at the spraying temperatures of from about 30 to about 200EC, preferably from about 50 to about 150EC, in particular from about 60 to about 120EC. If these liquids are added, as adhesion promoters, separately from the porous oxidic material, but simultaneously, a liquid having a boiling point which is considerably higher than the abovementioned temperatures will be chosen.
In a preferred embodiment, the porous oxidic material is suspended in alcohols, such as methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, tert-butanol and mixtures of two or more thereof. Particular preference is given to using a mixture of an alcohol, preferably one of the alcohols mentioned above, with water. Such a mixture generally comprises from about 1 to about 80% by weight, preferably from about 5 to about 70°s by weight, in particular from about 10 to about 600 by weight, in each case based on the total weight of the mixture of alcohol and water.
High-boiling liquids are those having a boiling point at atmospheric pressure of more than 150gC. Preferred high-boiling liquids are propanediol, glycerol, ethanediol, polyether, polyester, dipropylene glycol or mixtures of two or more thereof.
The organic viscosity-enhancing substance used may likewise be any prior art substances suitable for this purpose. Those preferred are organic, in particular hydrophilic, polymers, eg. cellulose, starch, polyacrylates, polymethacrylates,, polyvinyl alcohol, polyvinylpyrrolidone, polyisobutene and polytetrahydrofuran. These substances primarily promote the adhesion of the porous oxidic material on the support in the uncalcined state.
Amines or amine-like compounds, for example tetraalkylammonium compounds or aminoalcohols, and carbonate-containing substances, such as calcium carbonate, may be used as further additives. Such further additives are described in EP-A 0 389 041, EP-A
0 200 260 and WO 95/19222, the relevant contents of which are fully incorporated herein by reference.
The shaped body obtained by applying the mixture comprising the porous oxidic material to the inert support may be subjected to a calcination step. This calcination step may be superfluous when using the shaped body as a catalyst in a reaction which is carried out at high temperatures and in the presence of oxygen.
In this case, the calcination is effected in situ in the reactor.
This applies in particular when the novel mixture of porous oxidic material and metal acid ester (hydrolysate) is applied directly to the reactor wall and a reaction is then carried out at high temperature.
Otherwise, the shaped bodies are calcined. By this treatment, the shaped bodies are provided with the desired hardness and abrasion resistence. The calcination is generally carried out at from about 200EC
to 1,OOOgC, preferably from 250gC to 900EC, particularly preferably from about 300gC to about 800gC, preferably in the presence of an oxygen-containing gas.
The shaped bodies are preferably dried at from about 50 to about 200EC, preferably from about 80 to about 150EC, prior to calcination.
The shaped bodies according to the invention or produced S by a process according to the invention have very good catalytic activity and excellent mechanical abrasion resistance and are thus suitable for use in liquid phase reactions.
The novel shaped bodies contain virtually no particles finer than those with a minimum particle diameter of about 0.1 mm.
The shaped bodies according to the invention or produced according to the invention and comprising a porous oxidic material have improved mechanical stability while at the same time retaining their activity and selectivity in comparison with corresponding prior art shaped bodies.
The shaped bodies according to the invention or produced according to the invention can be employed for the catalytic conversion of organic molecules. Reactions of this type are, for example, oxidations, the epoxidation of olefins, for example the preparation of propylene oxide from propylene and H202, the hydroxylation of aromatics, for example phenol from benzene and H202 and hydroquinone from phenol and H202, the conversion of alkanes into alcohols, aldehydes and acids, isomerization reactions, for example the conversion of epoxides into aldehydes, and further reactions described in the literature utilizing such shaped bodies, in particular zeolite catalysts, as described, for example, in W. Holderich, Zeolites: Catalysts for the Synthesis of Organic Compounds, Elsevier, Stud. Surf. Sci. Catal., 49, Amsterdam (1989), 69-93, and, in particular for possible oxidation reactions, by B. Notari in Stud.

Surf. Sci. Catal., 37 (1987) 413-X25.
The shaped bodies discussed in detail above are particularly suitable for the epoxidation of olefins, preferably those of 2 to 8 carbon atoms, particularly preferably ethylene, propylene or butene, in particular propene, to give the corresponding olefin oxides.
Accordingly, the present invention relates in particular to the use of the shaped body described herein for the preparation of propylene oxide starting from propylene and hydrogen peroxide as described, for example, in EP-A
0 100 119.
EXAMPLES
Preparation Example 1 910 g of tetraethyl orthosilicate were initially taken in a 4 1 four-necked flask and 15 g of tetraisopropyl orthotitanate were added from a dropping funnel in the course of 30 minutes while stirring (250 rpm, paddle stirrer). A colorless, clear mixture formed. 1600 g of a 20o strength by weight tetrapropylammonium hydroxide solution (alkali metal content < 10 ppm) were then added and stirring was continued for a further hour. The alcohol mixture (about 900 g) formed from the hydrolysis was distilled off at from 90 to 100gC. The mixture was made up with 3 1 of water and the meanwhile slightly opaque sol was transferred to a 5 1 stainless steel stirred autoclave.
The closed autoclave (anchor stirrer, 200 rpm) was brought to a reaction temperature of 175gC at a heating rate of 3EC/min. The reaction was complete after 92 hours. The cooled reaction mixture (white suspension) was centrifuged and the sediment was washed several times with water until it was neutral. The solid obtained was dried at 110EC in the course of 24 hours (weight obtained 298 g).
The template remaining in the zeolite was then burnt off under air at 550EC in 5 hours (calcination loss: 14% by weight).
According to wet chemical analysis, the pure white product had a Ti content of 1.3~ by weight and a residual alkali content of less than 100 ppm. The yield was 97%, based on Si02 used. The crystallites had a size of from 0.05 to 0.25 um and the product showed a typical band at about 960 cm-1 in the IR spectrum.
Comparative Example 1 120 g of titanium silicalite powder, synthesized according to Preparation Example 1, were mixed with 48 g of tetramethoxysilane for 2 h in a kneader. 6 g of Walocel (methylcellulose) were then added. For conversion into a paste, 77 ml of a water/methanol mixture containing 25o by weight of methanol were then added. The material obtained was compacted for a further 2 h in the kneader and then shaped in an extruder to give 1 mm extrudates. The extrudates thus obtained were dried at 120gC for 16 h and then calcined at 500gC for 5 h. The epoxidation characteristics of the catalyst V1 thus obtained were evaluated in epoxidation experiments.
Comparative Example 2 120 g of titanium silicalite powder, synthesized according to Preparation Example 1, were mixed with 48 g of tetramethoxysilane for 2 h in a kneader. 6 g of Walocel (methylcellulose) were then added. For conversion into a paste, 77 ml of a water/methanol mixture containing 25$ by weight-_of methanol were then added. The material obtained was compacted for a further 2 h in the kneader and then shaped in an extruder to give 3 mm extrudates. The extrudates thus obtained were dried at 120EC for 16 h and then calcined at SOOEC for 5 h. The epoxidation characteristics of the catalyst V2 thus obtained were evaluated in epoxidation experiments.
Preparation Exam le 2 2500 g of Aerosil 200 obtained from Degussa were compacted together with 150 g of ammonia solution (300), 100 g of potato starch and 3000 g of water in a kneader and then shaped in an extruder to give 2 mm extrudates.
The extrudates thus obtained were dried at 110EC and then calcined at 500gC for 16 h. The extrudates thus obtained had an alkali metal content of 40 ppm. Half of the extrudates.were processed into 1-1.6 mm granules for the following examples.
Example 1 10 g of titanium silicalite powder obtained in Preparation Example 1 (particle sizes < 0.1 mm) were suspended in 100 g of methanol and 4 g of tetramethoxysilane. 100 g of Aerosil granules obtained in Preparation Example 2 were initially taken in a heated splash plate. The suspension of the titanium silicalite in methanol/tetramethoxysilane was sprayed on slowly while steadily rotating the splash plate. The granules thus obtained were dried at 120EC, screened and calcined at 500EC for 5 h. About 7 g of TS-1 powder were recovered by the screening procedure after drying.
Calcination gave abrasion-resistant shaped bodies suitable for liquid phase reactions. The shaped body contained 2$ by weight Ti silicalite, as determined by atomic emission spectroscopy. The epoxidation characteristics of the catalyst A thus obtained were evaluated in epoxidation experiments.
Example 2 . g of titanium silicalite powder obtained in Preparation Example 1 (particle sizes < 0.1 mm) were suspended in 100 g of methanol and 4 g of 10 tetramethoxysilane. 100 g of Aerosil granules obtained in Preparation Example 2 were impregnated with acetic acid and initially taken in a heated splash plate. The suspension of the titanium silicalite in methanol/tetramethoxysilane was sprayed on slowly while steadily rotating the splash plate. The granules thus obtained were dried at 120gC, briefly screened and calcined at 500EC for 5 h. About 2 g of TS-1 powder were recovered by the screening procedure after drying.
Calcination gave abrasion-resistant shaped bodies suitable for liquid phase reactions. The shaped body contained 5°s by weight Ti silicalite, as determined by atomic emission spectroscopy. The impregnation of the shaped bodies with acetic acid provided better adhesion of the TS-1 during spraying. The epoxidation characteristics of the catalyst B thus obtained were evaluated in epoxidation experiments.
Example 3 20 g of titanium silicalite powder obtained in Preparation Example 1 (particle sizes < 0.1 mm) were suspended in 300 g of methanol and 8 g of tetramethoxysilane. 100 g of Aerosil extrudates obtained in Preparation Example 2 were impregnated with acetic acid and initially taken in a heated splash plate. The suspension of the titanium silicalite in methanol/tetramethoxysilane was sprayed on slowly while steadily rotating the splash plate. The extrudates thus obtained were dried at 120EC, briefly screened and calcined at 500EC for 5 h. About 3 g of TS-1 powder were recovered by the screening procedure after drying.
Calcination gave abrasion-resistant shaped bodies suitable for liquid phase reactions. The shaped body contained 8.5o by weight Ti silicalite, as determined by atomic emission spectroscopy. The epoxidation characteristics of the catalyst C thus obtained were evaluated in epoxidation experiments.
Comparative Example 3 10 g of titanium silicalite powder obtained in Preparation Example 1 (particle sizes < 0.1 mm) were suspended in 100 g of methanol and 4 g of tetramethoxysilane. 100 g of silicon dioxide spheres (Siliperl AF-125 obtained from Engelhardt) were initially taken in a heated splash plate. The suspension of the titanium silicalite in methanol/tetramethoxysilane was sprayed on slowly while steadily rotating the splash plate. The spheres thus obtained were dried at 120EC, briefly screened and calcined at 500EC for 5 h. About 7 g of TS-1 powder were recovered by the screening procedure after drying. The shaped body contained 2% by weight Ti silicalite, as determined by atomic emission spectroscopy, and the alkali metal content was 400 ppm. The epoxidation characteristics of the catalyst V3 thus obtained were evaluated in epoxidation experiments.
Examples 4 to 9 Catalysts A to C and V1 to V3 were installed in a steel autoclave with basket insert and gassing stirrer in the amounts shown in Table 1. The autoclave was filled with 100 g of methanol, closed and tested for leakage. It _ - 20 -was then heated to 40EC, and 11 g_of liquid propene were metered into the autoclave. 9.0 g of an aqueous hydrogen peroxide solution (hydrogen peroxide content of the solution 30°s by weight) were then pumped into the autoclave by means of an HPLC pump, and the hydrogen peroxide residues in the feed lines were then flushed into the autoclave by means of 16 ml of methanol. The initial hydrogen peroxide content of the reaction solution was 2.5o by weight. After a reaction time of 2 h, the autoclave was cooled and depressurized. The liquid effluent was investigated cerimetrically for hydrogen peroxide. The analysis and the determination of the propylene oxide (PO) content were carried out by gas chromatography.
The PO and and hydrogen peroxide contents are shown in Table 1.
Catalyst V1 (TS-1, 1 mm extrudates) is significantly more active than Catalyst V2 (TS-l, 3 mm extrudates).
This indicates a poor utilization of the TS-1 extrudate having a diameter of 3 mm (V2). The supported catalysts A to C gave a higher PO yield although a lower amount of TS-1 was used. Owing to its high alkali metal content of 400 ppm, Catalyst V3 shows virtually no epoxidation activity.
Despite the high mechanical stress in the stirred steel autoclave, the supported catalysts showed no abrasion (no TS-1 in the effluent).

- Table 1 Batchwise autoclave epoxidation of, propene to give propene oxide Catalyst Amount TS-1 Amount of pp g2~2 . used content TS-1 used content content (g) (~ by (g) ($ by ($ by weight) weight) weight) Vl 0.55 90 0.5 1.71 1.0 V2 0.55 90 0.5 1.29 1.25 V3 5.5 2 0.11 0.05 2.30 A 15.5 2 0.31 2.45 0.49 B 5.5 5 0.275 1.86 0.94 C 5.3 8.5 0.45 1.56 1.29 Examples 10 to 13 Flows of 27. 5 g/h of hydrogen peroxide (20% by weight) , 65 g/h of methanol and 14 g/h of propene were passed through a reactor battery consisting of two reactors which had a reaction volume of 98 ml each and a downstream tube reactor having a volume of 13 ml, filled with the amount of the catalysts V1, V2, A and B shown in Table 2 at a reaction temperature of 40EC and a reaction pressure of 20 bar. The reaction mixture exited from the tube reactor and was depressurized to atmospheric pressure in a Sambay evaporator. The removed low boilers were analyzed on-line by gas chromatography.
The liquid reaction effluent was collected, weighed and also analyzed by gas chromatography.
The hydrogen peroxide conversion decreased over the running time of 30 h from initially 96$ and reached the value given in Table 2. The PO selectivity, based on hydrogen peroxide, was always more than 95~.

Table 2 -Continuous epoxidation of propene with hydrogen peroxide to give propylene oxide Catalyst Amount TS-1 TS-1 amount H2p2 used (g) content used (g) conversion ($ by after 30 h weight) Vl 0.55 90 0.5 1.0 V2 0.55 90 0.5 1.25 15.5 2 0.31 0.49 5.5 I5 10.27510.94 In the procedure, the supported TS-1 catalysts are also significantly more active than the catalysts used in the form of an unsupported catalyst (extrudate), based cn the amount of TS-1 used.
Despite the high mechanical stress in the stirred reactors, the catalysts showed no abrasion (no TS-1 in the effluent) in the experiments.

Claims

We claim:

1. A shaped body comprising an inert support and at least one porous oxidic material applied thereto and obtainable by applying a mixture comprising at least one porous oxidic material and at least one metal acid ester or a hydrolysate thereof or a combination of metal acid ester and hydrolysate thereof to the inert support, wherein the shaped body has micropores, mesopores, micro- and mesopores, micro- and macropores or micro-, meso and macropores.

2. A shaped body as claimed in claim 1 in the form of a non-spherical pellet, an extrudate, a granule, a tablet, a band-like structure or a structure having holes.

3. A shaped body as claimed in claim 1 or 2, wherein the porous oxidic material is a zeolite.

4. A shaped body according to claim 3, wherein the porous oxidic material is a titanium silicalite.

5. A shaped body as claimed in any of claims 1 to 4, wherein the metal acid ester is selected from the group consisting of an orthosilicic ester, an alkoxysilane, a tetraalkoxytitanate, a trialkoxyaluminate, a tetraalkoxyzirconate and a mixture of two or more thereof.

6. A process for preparing a shaped body as claimed in any of claims 1 to 5, which comprises applying a mixture comprising at least one porous oxidic material and at least one metal acid ester or a hydrolysate thereof or a combination of metal acid ester and hydrolysate thereof to an inert support.

7. A process as claimed in claim 6, wherein the mixture is applied by spraying.

8. A process as claimed in claim 6 or 7, wherein the mixture additionally comprises at least one alcohol or a mixture of at least one alcohol and water.

9. The use of a shaped body as claimed in any of claims 1 to 5 or of a shaped body produced by a process as claimed in any of claims 6 to 8 or of a mixture of two or more thereof for the epoxidation of organic compounds having at least one C-C double bond, for the hydroxylation of aromatic organic compounds, or for the conversion of alkanes to alcohols, ketones, aldehydes and acids.

10. The use of a shaped body as claimed in any of claims 1 to 5 or of a shaped body produced by a process as claimed in any of claims 6 to 8 for the preparation of propylene oxide starting from propylene and hydrogen peroxide.