IE48184B1 - Modified silica and germania and their use as catalysts - Google Patents

Abstract

Aluminium-or gallium modified silica or germania is prepared by reacting an aluminium (or gallium) derivative and a silicon (or germanium) derivative with a clathrating substance with the possible addition of a mineralising agent and an inorganic base, and crystallising the mixture thus obtained, so that a compound is formed which has the general formula: Si.(0.0012 - 0.0050)Al.Oy Ge.(0.0012 to 0.0050)Al.Oy Si.(0.0012 to 0.0050) Ga.Oy Ge.(0.0012 to 0.0050)Ga.Oy in which y is from 2.0018 to 2.0075. The modified silicas and the analogous compounds are efficient catalysts for a large number of reactions. A zeolite of formula (0.9+/-0.2)M2/n0.W2O3(5-100)YO2-2H2O in which M is H<+>, NH4<+>, metallic cations or cations derived from amino alcohols, W is Al or Ga, Y is Si or Ge and z is 0-40 of ZSM-5 type is referred to as a modification.

Description

This invention relates to a crystalline silica or germania modified with aluminium or gallium.

Many materials based on silica and alumina, both natural and synthetic, are known. More particularly, there are known materials called zeolites, which have absorbent, molecular sieve and catalytic properties. Such materials have a content of alumina relative to silica which varies within a wide range. The maximum silica/alumina ratio is 100:1, but this ratio is generally much smaller and is preferably in the neighbourhood of 2.

These materials, which contain aluminium in tetrahedral coordination as replacement for silicon, must possess, to be electrically neutral, cations capable of balancing the charges due to the presence of the tetrahedrally coordinated aluminium atoms.

The protonic acidity of such zeolites can be attributed to the hydrogen atoms which have been introduced to exchange such cations. On the other hand, crystalline silicas, due to their intrinsic nature, do not possess protonic charges so that they cannot display any acidic character, other than that inherent in the silicic acid.

A number of crystalline silicas such as cristobalite, tridymite and keatite are known. They are prepared according to procedures which have been widely disclosed by the scientific literature. For example Heidemann, in Beitr. Min. Petrog., 10, 242 (1964) describes the.reaction of an amorphous silica with 0.55% KOH at 180°C for - . :: Jj ' i,^'· ~'2$ days, whereby there is obtained a crystalline silica, called silica X, Ο which has, however, a specific surface area of about 10 m /g and a poor stability since it changes to cristobalite within five days and subsequently changes to quartz. More recently, Flanigen et al, Nature, 271, 512 (1978) have described a crystalline silica, namely silicalite, which has a high specific surface area and which, due to its hydrophobic properties, may be used for the purification of water polluted by organic substances.

According to the present invention there is provided aluminiummodified or gallium-modified silica or germania having a porous 1C crystalline structure, having a specific surface area greater than -3 150 m /g, having a proton concentration of from 4.3 x 10 to 4.7 x 10-1 milliequivelants per gram, and having one of the following general formulae: Si. (0.0012 to 0.0050) A1.0 15 Ge. (0.0012 to 0.0050) Al.0y Si. (0.0012 to 0.0050) Ga.Ou Ge. (0.0012 to 0.0050) Ga.O* wherein y is from 2.0018 to 2.0075. The present invention also provides a process for preparing such aluminium-modified or gallium modified silica or germania, which comprises reacting a derivative of silicon (or germanium) and a derivative of aluminium ( or gallium) with a substance having a templating or clathrating effect, the reaction being carried out in an aqueous medium, an alcoholic medium or an aqueous alcoholic medium; crystallising the reaction mixture at a temperature of from 100° to 220°C; cooling the reaction mixture; separating the precipitate formed in the reaction mixture; firing the 184 precipitate in air at a temperature of from 300° to 700°C; washing the fired product with boiling water having an ammonium salt dissolved therein; and firing the washed product in air at a temperature of from 300 to 700°C. The present invention also provides a process for the alkylation of a hydrocarbon to form a high octane high hydrocarbon wherein the alkylation is carried out in the presence of, as a catalyst, such aluminium-modified or gallium-modified silica or germania.

It has surprisingly been found in one aspect of the invention, that it is possible to obtain materials having a very high silica-toalumina ratio but which cannot be zeolites since the minimum amounts of aluminium contained therein cannot sustain a structure of the crystalline silicoaluminate type. On the other hand, these materials differ from crystalline silicas in that the introduction of tiny amounts of aluminium induces a wide variation of acidity. Such materials possess a protonic acidity equal to, or greater thanSi_that of the protonic forms of the zeolites themselves while maintaining the very high structural stability of crystalline silica, contrary to what is experienced for the protonic forms of zeolites A, X, Y (the only exception being that of the mordenite family) which are rather labile as they tend to be readily converted into the stabler silica aluminas.

The silica aluminas, as such, possess an acidity which is somewhat lower. For example, a commercial silica alumina containing 25% by wt. of alumina has a proton content, in mi Hi equivalents (meq) per gram of _3 catalyst, of the order of 1 x 10 . 818 4 It has been surprisingly found, furthermore, that by properly metering the quantity of aluminium in the materials, it is possible to adjust the acidity thereof so as to adapt it for the reaction for which the material is to be employed.

The silica modified by the introduction of aluminium atoms has the following general formula: Si.(0.0012 - 0.0050)A1.0y wherein y is from 2.0018 to 2.0075.

Depending upon the calcination (firing) temperature, greater or smaller amounts of water of crystallisation may be present.

To prepare the aluminium-modified silica of the present invention, it is preferred to use the following procedure: A derivative of silicon and a derivative of aluminium are reacted in an aqueous, alcoholic or hydro-alcoholic solution with a substance having a clathrating or templating effect, possibly in the presence of one or more mineralising agents to encourage crystallisation, and possibly in the presence of an inorganic base. The resultant mixture is allowed to crystallize in an enclosure for a period of time of from a few hours to many days at a temperature of from 100°C to 220°C, preferably at a temperature from 150°C to 200°C for a week. The mixture is allowed to cool and, upon collection on a filter, drying and firing at a temperature of from 300°C to 700°C, preferably at 550°C, for a time of from 2 hours to 24 hours, is carried out. The product is washed to remove the possibly exchangeable cationic impurities with boiling distilled water which contains an ammonium salt dissolved therein, preferably ammonium nitrate or ammonium acetate. The product is then fired again as above.

The derivative of silicon is preferably a silica gel (no matter how obtained) or a tetraalkyl orthosilicate such as tetraethyl orthosilicate or tetramethyl orthosilicate. The derivative of aluminium is preferably a salt of aluminium such as the nitrate of acetate.

The substance which displays templating or clathrating effect is preferably a tertiary amine, an aminoalcohol, an aminoacid, a polyhydric alcohol or a quaternary ammonium base such as a tetraalkyl ammonium base (e.g. NR4OH wherein R is an alkyl radical having from 1 to 5 carbon atoms) or a tetraalkylammonium base (e.g. NA^OH wherein A is a phenyl or an alkyl phenyl radical).

The substance having templating effect has the function of originating a crystalline structure with pores having a determined size, and thus is generally large molecules.

The mineralising agent is preferably an alkali metal or alkaline earth metal hydroxide or halide, for example LiOH, NaOH, KOH, Ca(0H)2> KBr, NaBr, Nal, Cal2 or CaBr2- The inorganic base is preferably an alkali metal or an alkaline earth metal hydroxide (e.g. NaOH, KOH and Ca(0H)2) or ammonia.

As regards the amount of the inorganic base and/or of the clathrating substance to be used, these amounts are generally lower than the stoichiometric amount relative to silica and are preferably from 0.05 to 0.50 mol per mol of silica.

The products are characterised by an acidity of the protonic type which can be varied by varying the silicon replacing cation which is introduced. For pure silica the number of milliequivalents of hydrogen per gram is 1 x 10 This acidity can be increased by the introduction of aluminium until the number of milliequivalents of hydrogen ions per gram is about 1 x 10 \ The materials according to the present invention are characterised by a well defined crystalline structure as can be seen in the X-ray diffraction spectra given in Figures 1 and 2 of the accompanying drawings and possess a high specific surface area which is over 150 m^/g and is generally from 300 tn^/g to 500 m^/g.

The presence of aluminium, which modifies the acidity of the silica, gives rise to the formation of crystalline materials the spectra of which can either be very similar to those reported in the literature for the crystalline silica called silicatite (Nature, 271, 512 (1978)), or, conversely, be remarkably different therefrom.

The aluminium-modified silica according to the invention can be employed for catalytic or absorption uses, either as such or when dispersed on a supporting body which is inert to a lesser or greater extent and which has a high or low specific surface area and porosity.

The supporting body improves the physical and mechanical stability and possibly also the catalytic properties of the material. The procedures used for obtaining supported materials are known in the art.

The amount of supporting body is generally from 1% to 90%, amounts of from 5% to 60% being preferred. The preferred supporting bodies are clays, silica, alumina, diatomaceous earth and silica-alumina.

The aluminium-modified silica according to this invention can be employed as a catalyst for a large number of reactions among which are the alkylation of benzene, more particularly the alkylation of benzene with ethylene and the alkylation of benzene with ethanol.

Examples of other uses are: (1) Alkylation of toluene with methanol to produce xylene, predominantly p-xylene; (2) Disproportionation of toluene to produce predominantly p-xylene; (3) Conversion of dimethyl ether and/or methanol or other lower alcohols to hydrocarbons (olefins and aromatics); (4) Cracking and hydrocracking; (5) Isomerisation of normal paraffins and naphthenes; (6) Polymerisation of compounds which contain olefinic or acetylenic bonds; (7) Reforming; (8) Isomerisation of polyalkyl substituted aromatic hydrocarbons such as o-xylene; (9) Disproportionation of aromatic hydrocarbons, especially toluene; (10) Conversion of aliphatic carbonyl compounds into at least partially aromatic hydrocarbons; (11) Separation of ethylbenzene from other Cg aromatic hydrocarbons; (12) Hydrogenation and dehydrogenation of hydrocarbons; (13) Methanation; The foregoing description relates to aluminium-modified silica.

However, gallium can be substituted for the aluminium and germanium can be substituted for the silicon.

In a preferred embodiment of the invention, the catalysts of the invention are used in the alkylation of C4 hydrocarbons, olefins and/or saturated hydrocarbons (paraffins), to form hydrocarbons having high octane numbers. As outlined above, the catalysts are porous and have 2 a specific surface area greater than 150 m /g.

The invention will now be illustrated by the following Examples: EXAMPLE 1 This Example illustrates the preparation of a porous crystalline silica in the crystalline lattice of which aluminium has been introduced as silicon-replacing element. This modified silica has been designated by us as catalyst TRS-22.

A Pyrex (Trade Mark) glass vessel kept in a nitrogen atmosphere was charged with 80 g of tetraethyl orthosilicate. The silicate was heated with stirring to a temperature of 80°C. There were added a solution, in 80 ml of distilled water, of 20 g of tetrapropylammonium hydroxide (obtained from tetrapropylammonium and moistened silver oxide so that it was free of inorganic alkaline bases). Stirring was continued at 80°C, until the mixture was homogeneous and clear. This took about one hour.

There were added 80 mg (milligrams) of Al(NOgJg.SHgO dissolved in 50 ml of absolute ethanol. A compact gel formed almost immediately, and distilled water was added thereto to make up to an overall volume of 200 ml, stirring being carried out if necessary. The mixture was brought to a boil so as to complete the hydrolysis and to drive off all the ethanol, i.e. that added and that formed by the hydrolysis.

The time taken by these steps was from 2 to 3 hours and the gel was converted, slowly and gradually, into a white powder, which is the precursor of the modified crystalline silica.

The mixture was made up to 150 ml with distilled water and the vessel was kept in an autoclave at a temperature of 155°C for 7 days.

Upon cooling, the solid which had formed was centrifuged at a speed of 10,000 rpm for 15 minutes. It was reslurried in distilled water and centrifuged once more. This washing step was repeated four times. The product was oven dried at 120°C. It was X-ray crystalline.

The product dried at 120°C, contained 8.3% by weight of SiOg, 0.2% by weight of AlgOg, 0.18% by weight of NagO and 0.02% by weight of KgO. Its loss on firing at 1100°C was 16.6%, and its molar ratio of SiOg to AlgOg was 704:1. The alkali metals present came from the reactants and from the glass, since they were not deliberately added.

In order to completely remove the alkaline impurities, the product was fired for 16 hours at 550°C in an air stream, was repeatedly washed with boiling distilled water containing ammonium acetate dissolved therein, and was fired again at 550°C for 6 hours. Its specific surface area, as determined by the BET method, was 444 m g. Its concentration of protons in milliequivalents per gram of sample was 1.5 x 10~\ EXAMPLE 2 This Example illustrates the preparation of a porous crystalline silica in the crystalline lattice of which traces of aluminium have been introduced as a replacement for the silicon. This modified silica has been designated by us as catalyst “TRS-O11.

A Pyrex glass flask equipped with a reflux condenser and maintained in a nitrogen atmosphere was charged with 40 g of tetraethyl orthosilicate and 120 ml of a 20% by weight aqueous solution of tetrapropyl ammonium hydroxide. The mixture was heated to boiling point. The final result was a clear, colourless solution which remained limpid even after refluxing for a long time.

There were added 30 mg of Al(N03)3.9Hg0 , whereupon the solution became opalescent and, by continuing the application of heat, a white powder separated therefrom.

Boiling was continued for 6 days, whereafter the mixture was allowed to cool, the solid product was collected on a filter and washed with distilled water and dried at 100°C. The product, dried at 100°C, was X-ray crystalline. It was fired for 16 hours at 550°C in an air stream and was subsequently repeatedly washed with boiling distilled water which contained ammonium acetate dissolved therein. Thereafter, the product was fired at 550°C once more for 6 hours.

The product thus obtained contained 96.2% weight of SiOg, 0.2% wt of Al203 and 0.02% wt of NagO + KgO. Its weight loss on firing at 1100°C was 3.58% and its molar ratio of SiOg to AlgOg was 816:1.

The traces of alkali metals which were present come from the reactants and the glass since they were not deliberately added. The specific surface area of the product, as determined by the BET method, p was 420 m /g. Its content of protons in milliequivalents per gram was 1.9 x 10-1.

EXAMPLE 3 This Example illustrates the preparation of a porous crystalline silica, designated by us as catalyst TRS-23, in the crystalline lattice of which aluminium has been introduced as a replacement for silicon and in the preparation of which there was used an organic base, namely tetraethylammonium hydroxide, different from the base used in Examples 1 and 2.

The procedure of Example 1 was employed, using 80 g of tetraethyl orthosilicate, 68 ml of a 25% by weight aqueous solution of tetraethylammonium hydroxide, 80 mg of Al2(N03)3.9HgO dissolved in ml of absolute ethanol and 2 g of NaOH pellets dissolved in 10 ml of distilled water, this mixture being maintained at a temperature of 155°C for 18 days.

The product, when dried at 120°C, was X-ray crystalline. Its content -6 of protons in mi Hi equivalents per gram after firing was 1.1 x 10 .

A thoroughly washed sample which had been fired at 550°C contained 96.3% by weight of Si02, 0.2% by weight of Al203 and 0.03% by weight of Na20. Its weight loss on firing at 1100°C was 3.47%, its molar ratio of Si02 to Al203 was 816:1, its specific surface area, as determined by the BET method, was 470 m/g, and its content of protons in milli*3 equivalents per gram was 4.3 x 10 .

EXAMPLE 4 This Example illustrates the preparation of a porous crystalline silica, designated by us as catalyst '‘TRS-19, in the crystalline lattice of which aluminium has been introduced as a replacement for silicon and in the preparation of which there is used an organic base, namely tetrabutyl ammonium hydroxide, different from those used in the previous Examples.

The procedure of Example 1 was employed, using 50 g of tetraethyl orthosilicate, a solution of 100 mg of Al(Ν03)3·9Η20 in 50 ml of absolute ethanol, a solution of 29 g of tetrabutylanmoniurn hydroxide (obtained from tetrabutyl ammonium bromide and moistened silver oxide) in 120 ml of distilled water and 2 g of NaOH dissolved in 20 ml of distilled water. This mixture was placed in an autoclave and held for 16 days at a temperature of 155°C. The product, dried at 120°C, was X-ray crystalline. Its content of protons in mi Hi equivalents per o “Ά gram, after firing at 550 C, was 4.5 x 10 .

A thoroughly washed sample contained 96.0% by weight of SiOg, 0.3% by weight of Alg03 and 0.03% by weight of NagO. Its weight loss on firing at 1100°C was 3.67%. Its molar ratio SiOg to AlgOg was 543:1, its specific surface area, as measured by the BET method, was 380 m /g, and its content of protons in mi Hi equivalents per gram was 2.5 x 1061.

Figure 1 of the accompanying drawings shows the X-ray diffration spectrum of the product.

EXAMPLE 5 This Example illustrates the preparation of a porous crystalline silica, designated by us as catalyst TRS-20, in the crystalline lattice of which aluminium has been introduced as a modifying element in place of silicon. The preparation of this silica was carried out without any inorganic alkaline base being present, the only alkaline cations present being those present as impurities in the reactants.

By the procedure of Example 1, there were reacted 40 g of tetraethyl orthosilicate, a solution of 100 mg of AI(N03)3. 9HgO in 50 ml of absolute ethanol, 50 ml of a 40% by weight aqueous solution of tetrapropyl ammonium hydroxide (obtained from tetrapropylammonium bromide and moistened silver oxide), to obtain a product free of alkaline inorganic bases. The mixture was maintained at 155°C for 10 days.

X-ray analysis indicated the crystalline character of the product dried at 120°C.

For use as a catalyst, the product was fired at 550°C in air for 16 hours and then repeatedly washed with boiling distilled water containing dissolved therein ammonium acetate. The product was fired once again at 550°C for 6 hours. 48184 The product thus obtained contained 96.1% by weight of Si02, 0.3% by weight of Al203 and 0.01% by weight of Na20, its weight loss on firing at 1100°C was 3.59%, its molar ratio of Si02 to AlgOg was 544:1, its specific surface area as determined by the BET method was as high as 500 m /g, and its concentration of-H ions per gram was 4.7 x 10'1 meq.

EXAMPLE 6 This Example illustrates the preparation of a porous crystalline silica, designated by us as catalyst ''TRS-57'1, in the crystalline lattice of which aluminium has been introduced as the modifier. In the preparation of the silica, triethanolamine was used.

There were reacted 80 g of tetraethyl orthosilicate, mg of Al(N03)3.9H20 dissolved in 50 ml of absolute ethanol, a solution of 27 g of triethanolamine in 50 ml of distilled water, the procedure being disclosed in Example 1. There were added 7 g of sodium hydroxide and the Pyrex glass vessel was placed in an autoclave and maintained at a temperature of 194°C for 7 days.

It was ascertained that the product, dried at 120°C, was X-ray crystalline. The X-ray diffraction spectrum of the product is shown in Figure 2 of the accompanying drawings.

The product, fired at 550°C, contained 96.2% by weight of Si02, 0.2% by weight of Al203 and 0.05% by weight of NagO. Its weight loss on firing at 1100°C was 3.55%, its molar ratio of Si02 to Al203 was 816:1, its specific surface area, measured by the 25 BET method, was 344 m2/g, and its content of H+ in meq per gram was 1.5 x 10'1.

EXAMPLE Ί (Comparative Example) This Example illustrates the lack of dehydrating catalytic properties of the modified crystalline silica TRS-22 prepared according to Example 1, but containing sodium cations, so that its content of protons in -4 milliequivalents per gram was as low as 4.1 x 10 .

The formation of dimethyl ether from methanol was used as the exemplary dehydration reaction. An electrically heated tubular reactor having an inside diameter of 8 mm was charged with 4 ml (2 g) of catalyst having a size of from 30 to 80 mesh (ASTM series).

A sample of the effluent of the reaction was taken downstream of the reactor and analysis was carried out gaschromatographically.

The catalyst was initially fired at 500°C for two hours in a nitrogen stream to remove the absorbed water, methanol was then fed in at a weight hourly space velocity (WHSV) of 1.5 g/g an hour, using an oven temperature of 275°C and subsequently of 400°C. Analysis of the reaction effluent showed the presence of methanol only at both temperatures.

EXAMPLE 8 (Comparative Example) This Example illustrates the absence of dehydrating properties of the modified crystalline silica TRS-23 prepared according to Example 3 and not thoroughly washed so that its content of proton in mini-β equivalents per gram was as low as 1.1 x 10 .

The procedure and the apparatus of Example 7 was used. The reactor was charged with 4 ml (2.8 g) of catalyst the grit size of which was from 30 to 80 mesh(ASTM series), and the catalyst was heated for two hours at 500°C in a stream of anhydrous nitrogen.

Methanol was fed in at a temperature of 240°C, 300°C and 400°C at a WHSV of 1.75 grams per gram an hour. In all three cases, no , 48184 dimethyl ether was found in the reaction effluent, i.e. methanol only was found.

EXAMPLE 9 This Example illustrates the excellent catalytic dehydrating 5 properties of the modified crystalline silica TRS-22 prepared according to Example 1 and having a content of protons in mi Hi equivalents per gram of 1.5 x 10\ The procedure and apparatus of Example 7 was used. The reactor was charged with 5 ml (3.5 g) of catalyst having a grit size of from 30 to 80 mesh (ASTM series).

After firing the catalyst for 2 hours under an anhydrous nitrogen stream to remove the absorbed water, methanol was fed in at WHSV of 1.5 g/g per hour at reactor temperatures of 250°C and 265°C.

Analysis of the reactor effluent, which consisted of dimethyl ether, unreacted methanol and water without the presence of by-products detectable by gas chromatography, gave the results tabulated in Table 1 below.

It can be seen that the crystalline silica has an excellent dehydrating activity, with conversion percentages even higher than those described in our Patent Specification No. 43445. 2θ By using TRS-22 at 250°C and at 265°C, there are obtained, at a WHSV of 1.5 conversions of methanol which are, respectively, equal to and higher than those which can be obtained at 300°C and at a WHSV of 1, using active alumina which has been treated with silicon compounds.

EXAMPLE 10 (Comparative Example) This Example illustrates the conversion of dimethyl ether into hydrocarbons, particularly light olefins, using modified crystalline silica TRS-22 prepared according to Example 1 and containing sodium cations, the content of protons in mi Hi equivalents per gram -4 of catalyst being 4.1 x 10 , An electrically heated tubular reactor having an inside diameter of 8 mm was charged with 2 ml (1 g) of the catalyst having a grit size between 30 and 80 mesh (ASTM series).

The catalyst was heated to 550°C for 2 hours in a nitrogen stream to remove absorbed water, if any. Gaseous dimethyl ether was fed in while heating all of the pipes to prevent condensation. Downstream of the reactor, a heated sampling appliance was installed, to permit the introduction of the reactor effluent into a gaschromatograph in which analysis of the reaction products is carried out.

As regards the calculation of the conversion, it is to be borne in mind that the methanol which is formed by partial hydration of the dimethyl ether is considered as an unreacted product, so that the molar conversion is based on the dimethyl ether which has been converted into hydrocarbons, carbon monoxide and carbon dioxide. The molar selectivities on the products are referred to the number of mols of dimethyl ether which have been converted into the indicated product, relative to the total number of reacted mols. The results obtained are tabulated in Table 2 below. The Table clearly shows that the catalyst is not very active and not very selective, inasmuch as considerable amounts of carbon monoxide and carbon dioxide and methane are formed.

EXAMPLE Π This Example illustrates the conversion of dimethyl ether into hydrocarbons, particularly light olefins, using the modified crystalline silica TRS-22 prepared according to Example 1 having a concentration of protons of 1.5 χ 10”1 milliequivalents per gram.

The procedure and the apparatus of Example 9 was used. The reactor was charged with 3 ml (1.5 g) of catalyst having a grit size of from 30 to 80 mesh (ASTM series).

The catalyst had previously been heated to 550°C for 2 hours in 10 a nitrogen stream to remove absorbed water.

The results obtained are tabulated in Table 3 below. Comparison with Table 2 clearly shows that as the acidity is varied, the behaviour of the catalyst is improved.

EXAMPLE 12 This Example illustrates the activity, in the alkylation of benzene with ethylene, of catalyst TRS-22 (1.5 x 10~^ meq H+ per gram).

An electrically heated tubular reactor having an inside diameter of 8 mm was charged with 1.2 ml (0.8 g) of catalyst TRS-22 having a grit size of from 30 to 50 mesh. By use of a metering pump, benzene was first passed through a preheater system wherein it mixed with ethylene of a preselected rate of flow. .3 The mixture was passed into the reactor.

The pressure was 20 kg/cnf1, the LHSV was 14 and the molar ratio of CgHg to CgH^ was 7:1. The reaction products were gaschromatographically analysed. Table 4 tabulates the results obtained.

EXAMPLE 13 This Example illustrates the regeneration of the catalyst used in the previous Example. After 400 hours of operation, the catalyst was regenerated at 550°C in a properly adjusted air stream for 5 hours.

On completion of the regeneration, the system was purged with nitrogen for one hour, still at 550°C, whereafter the reaction was restarted under the same conditions as reported previously. Table 5 below gives the results obtained.

EXAMPLE 14 This Example illustrates the activity, in the alkylation of benzene with ethanol, of catalyst TRS-O.

An electrically heated tubular reactor having an inside diameter of 8 mm was charged with 1.2 ml (0.8 g) of the catalyst having a grit size of from 30 to 50 mesh. By use of a metering pump, the reaction mixture, which consisted of benzene and ethanol in a molar ratio of 5:1 were introduced first into a preheater and then into the reactor.

The reaction is carried out at 440°C, at a pressure of 20 Kg/cm^, at a LHSV of 10 and using a molar ratio of CgHg to CgHgOH of 4:1.

The reaction products were gaschromatographically analysed. The results obtained are given in Table 6.

EXAMPLE 15 ml of the aluminium-modified silica TRS-20 prepared as in Example 5 were impregnated with an aqueous solution of L^PtClg such that the content of platinum in the catalyst was 0.2% by weight. The platinum was reduced to the elemental state at 600°C in a hydrogen stream, . 48184 the catalyst was introduced into an electrically heated tubular reactor having an inside diameter of 20 mm.

The ability of the catalyst to purify the exhaust gases of a motor car was determined with two typical reactions, namely oxidation of propylene to carbon dioxide and oxidation of carbon monoxide to carbon dioxide.

Test A A gas consisting of 800 ppm of propylene, 8% of oxygen and the balance nitrogen was preheated to 120°C and passed over the catalyst at a Gaseous Hourly Space Velocity (GHSV) of 50,000 hours'} (reciprocal hours). The conversion of propylene was 99%. The same gaseous mixture, preheated to 90°C, was fed over the catalyst at a GHSV of 20,000 hours'^, and a conversion of 99% of the propylene was obtained.

Test B A gas consisting of 2.5% of CO, 8% of oxygen and the balance nitrogen was preheated to 80°C and passed over the catalyst at a GHSV of 50,000 hours’}. The conversion of CO was 59%.

The same gaseous mixture, preheated to the same temperature, was fed over the catalyst at a GHSV of 50,000 hours}, and the conversion of CO was 99%.

The temperatures above, i.e. from 80°C to 120°C, must be correctly regarded as exceptional since the best commercial catalyst as used in catalytic silencers can effect the same conversions of propylene and carbon dioxide at the same space velocities, but only at temperatures above 150°C. 818 4 EXAMPLE 16 This Example illustrates the activity, in the alkylation of benzene with ethylene, of catalyst TRS-57 prepared according to Example 6.

The reaction was carried out in a tubular reactor of the fixed-bed type, having an inside diameter of 8 mm and being electrically heated. There was introduced into the reactor, 1.2 ml (0.85 g) of the catalyst, having a grit size of from 30 to 50 mesh. By use of a metering pump, benzene was introduced, first into a preheater system (where it merges with a preselected rate of flow of ethylene) and then into the reactor. The reaction was carried out at a pressure of 20 kg/cm , at a temperature of 440°C, at a LHSV of 14 and using a molar ratio of εθΗβ to CgH^ of 7:1. The reactor effluent was gaschromatographically analysed.

Table 7 below gives the results obtained. _ EXAMPLE 17 IO -The catalyst which had been used for the reaction of Example 16 was subjected to an in situ regeneration using a stream of air diluted with nitrogen at 500°C.

On completion of the regeneration, the catalyst was again used for the alkylation of benzene with ethylene, under the same conditions. The results tabulated in Table 8 below are a clear indication of how simple and advantageous it is to regenerate the catalyst.

EXAMPLE 18 This Example illustrates the activity of catalyst TRS-57 as described in Example 6 in the alkylation of benzene with ethanol.

The reaction was carried out in an electrically heated, fixed-bed, tubular reactor, into which 1.2 ml (0.85 g) of the catalyst, having a grit size of from 30 to 50 mesh, had been introduced. Via a metering pump, the reaction mixture, namely benzene and ethanol, was introduced first into a preheater assembly and then into the reactor. The reaction was carried out at a pressure of 20 kg/cm^, at a temperature of 440°C, at a LHSV of 10 and using a molar ratio of ΟθΗθ to CgH^OH of :1. The effluent was gaschromatographically analysed. Table 9 below gives the results obtained.

EXAMPLE 19 For alkylating isobutene with normal butenes, a porous crystalline silica, as obtained in Example 5, in the crystalline lattice of which aluminium has been introduced as a replacement for silicon, was employed as the catalyst.

A small reactor as described in Example 7 was charged with 3 ml (1,9g) of the catalyst, having a grit size of from 30 to 50 mesh.

The pressure used was 20 kg/cm and the molar ratio of isobutene to normal butene was 15:1. The other conditions used and the results obtained are tabulated in Table 10 below.

TABLE 1 Temperature (°C) 250°C 265°C Pressure (bar) 1 1 WHSV (g/g hourly 1.5 1.5 Conversion of CH^OH (mol %) 82.4 88.1 TABLE 2 Test Temp. (°C) Press. (bar) WHSV Conversion per pass (mol %) Products (mol %) co+co2+ch4C2H4C3H6 Γ + b4 1 375 I 0.65 2.3 5.0 14.9 30.1 50.0 2 475 1 0.20 97.0 10.9 6.5 26.1 56.5 TABLE 3 Test Temp. (°C) Press. (bar) WHSV Conversion per pass (mol %) Products (mol %) co+ co2+ch4C2H4C3H6 c + b4 1 305 1 2.7 38.8 0.5 30.1 24.3 45.1 2 335 1 2.7 87.9 0.5 23.0 19.9 56.6 3 365 1 4.7 97.3 0.5 19.0 18.8 61.7 4 365 1 6.7 87.4 0.5 23.2 19.7 56.6 5 485 1 6.7 97.1 0.5 18.3 18.7 61.9 6 485 1 8.7 87.1 0.5 20.1 18.2 61.2 7 440 1 9.0 92.1 0.5 16.5 15.2 67.8 TABLE 4 Run (hours) Temp. (°C) Mol % of ethylbenzene in product Mol % of di ethylbenzene in product Conversion of ethylene m 10 440 13.8 1.50 100.0 50 440 13.7 1.55 100.0 100 i440 13.9 1.45 100.0 150 440 13.9 1.45 100.0 200 440 13.8 1.50 100.0 250 440 11.9 0.80 80.8 300 440 8.2 0.25 51.8 320 470 11.5 0.70 76.7 350 470 10.9 0.65 72.6 400 470 10.3 0.60 ' 68.2 TABLE 5 Run (hours) Temp (°C) Mol % of ethylbenzene in product Mol % Of diethylbenzene in product Conversion of ethylene (%) 10 440 13.7 1.55 100.0 50 440 13.6 1.40 97.6 100 440 13.8 1.50 100.0 150 440 13.9 1.45 100.0 200 440 13.7 1.55 100.0 250 440 12.2 0.95 83.9 300 440 10.3 0.60 68.45 350 440 9.8 0.38 62.85 Λ TABLE 6 Run (hours) Mol % of ethylbenzene in product Mol % Of diethylbenzene in product Conversion of CgHgOH (%) 50 19.0 1.2 100 100 19.0 1.2 100 150 19.0 1.2 100 200 19.0 1.2 100 300 19.0 1.2 100 400 19.0 1.2 100 TABLE 7 Run (hours) Mol of ethylbenzene in product diet{$lblnS£ne in product Conversion of ethylene m 10 13,9 1.35 100.0 50 13.9 1.35 100.0 100 14.0 1,30 100.0 150 13.8 1.30 98.8 200 13.9 1.35 100.0 250 13.7 1.28 97.9 300 12.5 1.02 87.6 350 1 11.3 0.90 78.9 TABLE 8 Run (hours) Mol % of ethylbenzene in product Mol % of diethylbenzene in product Conversion of ethylene (%) 10 14.0 1.30 100.0 50 13.9 1.35 100.0 100 13.8 1.40 100.0 150 13.9 1.35 100.0 200 13.8 1.40 100.0 250 13.2 1.19 93.8 300 12.8 0.95 88.5 TABLE 9 Run Mol % of ethylbenzene in the product Mol % of diethylbenzene in the product Conversion of CgHgOH (%) 50 18.8 1.3 100 1 100 19.0 1.2 100 ; 150 18.8 1.3 100 200 19.0 1.2 100 250 19.0 1.2 100 300 19.0 1.2 100 ' 400 19.0 1.2 100 TABLE 10 Temp. (°C) LHSV (rec. hrs) % alkylation with respect to the butenes Composition of the products 250 1.3 100 about 90% isoparaffins + about 20% aromatics 350 1.3 100 about 50% isoparaffins + about 50% aromatics 350 5.0 90 about 70% isoparaffins + about 30% aromatics Attention is drawn to our Patent Specifications Nos. 1169/79

Claims (15)

1. Aluminium-modified or gallium-modified silica or germania having a porous crystalline structure, having a specific surface area 2 greater than 150 nr/g, having a proton concentration of from -3 -1

2. A material as claimed in claim 1, substantially as described in any of the foregoing Examples.

3. A process for preparing aluminium-modified or galliummodified silica or germania as claimed in claim 1, which comprises reacting a derivative of silicon (or germanium) and a derivative of aluminium (or gallium) with a substance having a templating or clathrating effect, the reaction being carried out in an aqueous medium, an alcoholic medium or an aqueous alcoholic medium; crystallising the reaction mixture at a temperature of from 100 to 220°C; cooling the reaction mixture; separating the precipitate formed in the reaction mixture; firing the precipitate in air at a temperature of from 300 to 700°C; washing the fired product with boiling water having an ammonium salt dissolved therein; and firing the washed product in air at a temperature of from 300 to 700°C. 4. 818 4 23. A process according to any of claims 3 to 22, wherein a derivative of germanium and/or a derivative of gallium is used, and wherein an aminoalcohol is used as a crystallisation encouraging agent. 5 24. A process according to claim 3, substantially as described in any of the foregoing Examples. 25. Aluminium-modified or gallium-modified silica or germania, prepared by a process according to any of claims 3 to 24. 26. A process for the alkylation of a hydrocarbon to form a high

4. A process according to claim 3, wherein the reaction mixture is crystllised for a time of from a few hours to a number of days. 4.3 x 10 to 4.7 x 10 milliequivalents per gram, and having one of the following general formulae: Si. (0.0012 to 0.0050) A1.0 y Ge. (0.0012 to 0.0050) A1.0 y Si. (0.0012 to 0.0050) Ga.O y Ge. (0.0012 to 0.0050) Ga.0 y wherein y is from 2.0018 to 2.0075.

5. A process according to claim 3 or 4, wherein the precipitate is fired for a time of from 2 to 24 hours. 5

6. A process according to any of claims 3 to 5, wherein the washed product is fired for a time of from 2 to 24 hours.

7. A process according to any of claims 3 to 6, wherein the derivative of silicon is a silica gel or a tetraalkyl orthosilicate.

8. A process according to claim 7, whrein the tetraalkyl orthosilicate

9. A process according to any of claims 3 to 8, wherein the derivative of aluminium is a salt. 10. Octane hydrocarbon, wherein the alkylation is carried out in the presence of, as a catalyst, aluminium-modified or gallium-modified silica or germania as claimed in claim 1 or 25. 27. A process according to claim 26, wherein the hydrocarbon contains four carbon atoms.

10. A process according to claim 9, wherein the derivative of aluminium is aluminium nitrate or aluminium acetate. 15 10 is tetraethyl orthosilicate or tetraroethyl orthosilicate.

11. A process according to any of claims 3 to 10, wherein the substance having a templating or clathrating effect is a tertiary amine, an amino alcohol, an aminoacid, a polyhydric alcohol or a quaternary ammonium base.

12. A process according to claim 11, wherein the quaternary ammonium base is a tetraalkylammonium base of the formula NR^QH, wherein R is 20 an alkyl radical having from 1 to 5 carbon atoms, or a tetraarylammonium base of the formula NA^OH, wherein A is a phenyl or an alkylphenyl radical.

13. A process according to any of claims 3 to 12, wherein the quantity of the substance(s) having a templating or clathrating effect is less than the stoichiometric amount with respect to silica or germania.

14. A process according to claim 13, wherein the quantity of the substance having a templating or clathrating effect is from 0.05 to 0.50 mol per mol of silica or germania. 15. A process according to any of claims 3 to 14, wherein the reaction is carried out in the presence of (a) at least one mineralising agent for encouraging crystallisation and/or (b) at least one inorganic base. 16. A process according to claim 15, wherein the or each mineralising agent is a hydroxide or halide of an alkali metal or alkaline earth metal. 17. A process according to claim 16, wherein the hydroxide or halide of alkali metal or alkaline earth metal is selected from LiOH, NaOH, KOH, Ca(0H) 2 , KBr, NaBr, Nal, Cal 2 and CaBr 2< 18. A process according to claim 15, wherein the inorganic base is ammonia or a hydroxide of an alkali metal or an alkaline earth metal. 19. A process according to claim 18, wherein the hydroxide of the alkali metal or alkaline earth metal is NaOH, KOH or Ca(0H) 2 . 20. A process according to any of claims 15 to 19 wherein the quantity of the inorganic base(s) used is less than the stoichiometric amount with respect to silica or germania. 21. A process according to claim 20, wherein the quantity of the inorganic base(s) used is from 0.05 to 0.50 mol per mol of silica or germania. 22. A process according to any of claims 3 to 21, wherein a derivative of germanium and/or a derivative of gallium is used, and wherein the crystallisation temperature is from 170 to 210°C.

15. 28. A high octane hydrocarbon obtained by a process according to claim 26 or 27.