SE439437B - ALUMINUM MODIFIED SILICON Dioxide AND SET FOR ITS MANUFACTURING - 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

Crystalline silica, called silica X, which, however, has a specific surface area of about 10 m 2 / g and poor stability, as it ages to cristobalite within five days and then turns into quartz, 'Recently, Flanigen et al., Nature, gll, 512 (1978) have obtained a crystalline silica, silicalite, which has a high specific surface area and which, due to its hydrophobic properties , has been proposed for the purification of water contaminated with organic substances.

An object of the present invention is to modify the properties of crystalline silica with aluminum while maintaining the stability of the silica, so that it can be used as a catalyst or for the preparation of catalysts. Surprisingly, it has been found that it is possible to obtain materials with a very high silica-alumina ratio which cannot be zeolites, since the insignificant amounts of aluminum in the material cannot be thought to correspond to a structure of the type crystalline silicoaluminate. On the other hand, these new materials differ sharply from the crystalline silicas, in that the introduction of very small amounts of aluminum causes a change in the acidity within wide limits.

These materials in fact have a protonic acidity equal to or greater than the protonic acidity of the protonic forms of the zeolites, while maintaining the very high structural stability of a crystalline silica, in contrast to what as is the case with the protonic forms of zeolites A, 'X and Y (with the exception of the mordenite group only), which are rather unstable in that they tend to be rapidly converted to more stable silica-alumina compounds.

As such, the silica-alumina compounds have a slightly lower acidity. For example, a commercial silica-alumina containing 25% by weight alumina has a concentration expressed as H + milliequivalents (meq) per gram of catalyst of the order of 1.1o'3.

. Furthermore, it is surprising that by correctly adjusting the amount of aluminum in the materials, it is possible to adjust the acidity so that it is specially adapted to the area required for the type of aluminum. reaction, for which the material in question is to be used.

An object of the invention is to provide a silica which is modified by the introduction of aluminum atoms in such a way that the material acquires the acidity properties and the catalytic activity which are most suitable for certain reactions.

Another object of the invention is to provide a method which is advantageously useful for producing materials of the type described above.

The silica, which is modified by the introduction of aluminum atoms, has according to the invention the following general formula: 1 Si. (0.00l2-0.0050) Al. O where Y is from 2.0018 to 2.0075.

Depending on the calcination temperature, larger or Y smaller amounts of crystal water may be present.

In order to obtain the aluminum-modified silica according to the invention, it is advantageous to apply the production method described below.

A derivative of silicon and a derivative of aluminum may react in aqueous, alcoholic or hydroalcoholic solution with a substance having a network-forming (climbing-forming) or bridging effect, possibly with the addition of one or more mineralizing agents to promote crystallization, and optionally also an inorganic base, allowing the resulting mixture to crystallize in a vessel for a period of time from a few hours to several days at a temperature from 10 ° C to 22 ° C, preferably between 100 ° C and 200 ° C for one week, allow the whole to cool and then, after collecting the obtained material on a filter, dry it and heat it to a temperature between 300 ° C and 700 ° C, preferably at about 550 ° C, for a time between 2 ° C. h and 24 h, wash the material to remove any replaceable cationic contaminants with boiling distilled water containing in solution an ammonium salt, preferably ammonium nitrate or ammonium acetate at, and 'èoon QUALITY 7905453-2 10 15 20 25 30 35 4 possibly repeating the said heating treatment.

The silicon derivatives can be selected from silica gel, it being irrelevant how they are obtained, or a tetraalkyl orthosilicate, for example tetraethyl orthosilicate and tetramethyl orthosilicate.

The aluminum derivatives can preferably be selected from aluminum salts, for example nitrate and acetate.

The crosslinking or crosslinking agents may be selected from tertiary amines, amino alcohols, amino acids, polyhydric alcohols and quaternary ammonium bases, for example tetraalkylammonium (NR 4 OH, where R is an alkyl radical having from 1 to 5 carbon atoms), or tetraarylammonium (N A is a phenyl or alkylphenylreaalkyl). The purpose of the bridging substances is to give a crystalline structure with pores of a certain size and thus formed of molecules of adequate size.

The mineralizing agents can be selected from alkali metal hydroxides and halides and alkaline earth metals, for example LiOH, NaOH, KOH, Ca (OH) 2, KBr, NaBr, Nal, CaI2, CaBr2.

The inorganic base may be selected from hydroxides of alkali metals and alkaline earth metals, preferably NaOH, KOH, Ca (OH) 2 and ammonia.

The amount of inorganic base and / or mesh-forming substances is generally lower than the stoichiometric amount with respect to the silica and preferably from 0.05 to 0.50 moles per mole of silica. The product thus obtained is characterized by a protonic acidity which can be controlled by varying the Si-replacing cation introduced. For pure silica, there are a number of milliequivalents of hydrogen ions per gram of l.l0_3, but this acidity can be increased by the introduction of aluminum until a number of milliequivalents of hydrogen ions per gram of about l.l0-1 is reached.

The materials of the present invention are characterized by well-defined crystal structure, as evidenced by the X-ray diffraction spectra shown in the accompanying Figures 1 and 2. The materials have a high specific surface area, namely over 150 m2 / g and usually between 300 m2 / g. g and 500 m2 / g. 10 15 20 25 30 35 40 7905453-2 5 The presence of aluminum, which so radically modifies the acidity of the silica, results in the formation of crystalline materials, the spectra of which are either very similar to those reported in the literature with respect to crisis. tallin silica called silicate (Nature, gll, 512 (1978), or remarkably different from them.

Aluminum silica modified according to this invention can be used for catalytic purposes and absorption, either as such or dispersed on a more or less inert support with high or low specific surface area and porosity. A The task of the carrier is to improve the physical and mechanical stability and possibly also the catalytic properties of the material in question. The procedure that can be used to obtain a worn material can be selected from well known ones. The amount of carrier may be between 1% and 90%, but is suitably in the range of 5% to 60%.

Suitable carriers include clays, silica, alumina, diatomaceous earth, silica-alumina and many others.

The aluminum-modified silica according to the present invention can be advantageously used as a catalyst for a large number of reactions, among which may be mentioned alkylation of benzene, especially alkylation of benzene with ethylene and ethanol.

Other uses are: 1. Alkylation of toluene with methanol to produce xylene, mainly paraxylene. 2. Disproportionation of toluene to produce predominantly paraxylene. Conversion of dimethyl ether and / or methanol or other lower alcohols to hydrocarbons (olefins and aromatics). 4. Cracking and hydrocracking. 5. Isomerization of nor.paraffins and naphthenes. Polymerization of compounds containing olefin or acetylene bonds. 7. Reformation. 8.-Isomerization of polyalkyl-substituted aromatics, for example osylene. 10 15 20 25 30 35 40 7905453-2 6 _ "om -.., _ 9. Disproportionation of aromatics, especially toluene. 7 l0. Conversion of aliphatic carbonyl compounds to at least partially aromatic hydrocarbons. Ll. Separation of ethylbenzene from others C8 aromatic hydrocarbons.12 Hydrogenation and dehydrogenation of hydrocarbons 13. Methanation.

The invention is further illustrated by the following examples.

Example Gel 1 This example is intended to illustrate the preparation of porous crystalline silica TRS-22, in whose crystal lattice aluminum has been introduced as a replacement for silicon.

A vessel of heat-resistant glass, kept in a nitrogen atmosphere, is charged with 80 g of tetraethylorthosilicate (TEOS), which is heated with stirring to 8000. A solution of 20 g of tetrapropylammonium hydroxide, obtained from tetrapropylammonium and moist silver oxide, to give a product free of inorganic alkaline bases, in 80 ml of distilled water is added with stirring, which is continued at 80 ° C until the mixture becomes homogeneous and clear, which takes about an hour.

Then so mg A1 (No3) 3.9H2o dissolved in so m1 ethanol is added. Immediately a compact gel is formed, which is added to distilled water up to a total volume of 200 ml, if necessary with stirring, and the mixture is boiled to complete the hydrolysis and expel all ethanol, i.e. both that which is added and that which is formed during the hydrolysis.

This takes between 2 and 3 hours and the gel is gradually converted to a white pulse, which is a precursor to the modified crystalline silica. I To the mixture is added 150 ml of distilled water, after which the glass vessel is placed in an autoclave, where it is kept at 155 ° C for 7 days. The solid product is dried at 10,000 rpm for 15 minutes, reslurried in distilled water and centrifuged and the product obtained is dried. After cooling, the car wash is centrifuged repeatedly four times. at 120 ° C and can be found to be X-ray crystalline.

Chemical analysis on the sample, dried at 120 ° C, gives the composition 83.0% SiO2, 0.2% Al2O3, 0.18% Na2O. and 0.02% K2O, all by weight. Weight loss on heating to 10 15 20 25 30 7 7905453-2 7 11oo ° c is 1e, s%. the noi ratio sioz / A12o3 is 704.

Alkali metals present come from the reactants and from the glass, as they have not been intentionally added.

To completely remove any alkaline contaminants from the compound, it can be heated for 16 hours to 550 ° C in air stream and then repeatedly washed with boiling distilled water containing in solution aluminum acetate, with repeated heating to 550 ° C for 6 hours .

The specific surface area, determined according to the BET method, is 444 m2 / g.

The concentration of protonic milliequivalents per gram is 1.5.1o'l.

Example 2 This example is intended to show the preparation of the porous crystalline silica TRS-O, in whose crystal lattice traces of aluminum have been introduced as a replacement for silicon.

A flask of refractory glass, equipped with a reflux condenser and kept in a nitrogen atmosphere, is charged with 40 g TEOS and 120 ml of a 20% (w / w) solution of tetrapropylammonium hydroxide, after which the mixture is heated to boiling.

You get a clear, colorless solution, which remains clear even after long reflux treatment.

At this stage, 30 mg of Al (NO3) 3.9H2O are added and the liquid becomes opalescent and on continued heating a white powder is excreted therein.

Boiling is continued for 6 days, after which the mixture is allowed to cool, the solid material is collected on a filter and washed with distilled water and dried at 100 ° C.

The dried product is X-ray crystalline. then heated for 16 hours at 550 ° C in air stream and then washed repeatedly with boiling distilled. water containing in solution ammonium acetate, after which the solid obtained is heated a further batch at 550 ° C for 6 hours.

Chemical analysis of the product obtained gives the composition 96.2% SiO2, 0.2% Al2O3, and 0.02% Na2O + K2O, all weight loss on heating to 110 ° C is the molar ratio SiO2 / Al2O3 is 816. calculated by weight . 3.58%. 7905455-2 8 The traces of alkali metals come from the reactants and the glass, as they have not been added intentionally. The specific surface area, determined according to the BET method, is 420 m2 / g.

The concentration in protonic milliequivalents per 5 grams is 1, 9.10_1.

Example 3 This example is intended to illustrate the preparation of a porous crystalline silica, designated TRS-23, in whose crystal lattice aluminum was introduced as a replacement for silicon 10 and in the preparation of which another organic base, tetraethylammonium hydroxide, was used instead of the base according to Example len len and.2. The procedure is the same as in Example 1, reacting between 80 g of tetraethylorthosilicate, 68 ml of a 25% (w / w) aqueous solution of tetraethylammonium hydroxide, 80 mg of 15 Al2 (NO3) 3.9H2O dissolved in 50 ml of absolute ethanol and 2 g of NaOH dissolved in 10 ml of distilled water, keeping the mixture at 155 ° C for 18 days.

In the product, dried at 120 ° C, is X-ray crystalline.

The concentration of protonic milliequivalents per gram (after heating to sso ° c) is 1,1.1o'6.

Chemical analysis on a thoroughly washed sample, which is then heated to 550 ° C, gives the composition 96.3% SiO 2, 0.2% Al 2 O 3 and 0.03% Na 2 O, all by weight. Weight loss on heating to 1200 ° C is 3.47%. The molar ratio SiO2 / Al2 O3 .25 is 816.

The specific surface area, determined according to the BÉT method, is 470 mg / g. The concentration of protonic milliequivalents per gram is 4,3,100 "3. Example 4 This example is illustrative of the preparation of a porous crystalline silica, designated TRS-19, in whose crystal lattice aluminum has been introduced as a substitute for silicon.

In the production of this silica, an organic base 35 has been used, which differs from those used in the previous example. It is tetrabutylammonium hydroxide.

The procedure is the same as in Example 1 for the reaction between 50 g of tetraethylorthosilicate, a solution of 100 ml of AlNO 9 H 2 O in 50 ml of absolute ethanol, a solution of 29 g of 3) 3u 10 15 20 25 30 35 7905453-2 9, u _ tetrabutylammonium hydroxide (obtained from tetrabutylammonium bromide and moistened silver oxide) in 20 ml of distilled water and 2 g of NaOH, dissolved in 20 ml of distilled water.

This mixture is placed in an autoclave and kept for 16 days at 15 ° C.

The product, dried at 120 ° C, is X-ray crystalline.

The concentration of protonic milliequivalents per gram (after reaching 55 ° C) is 4, s.lo'4. Chemical analysis on a thoroughly washed sample gives the composition 96.0% S102, 0.3% Al2O3 and 0.03% Na2O, all by weight. the weight loss_vla netting to lloo ° c is 3.67%.

The molar ratio SiO2 / Al2O3 is 543..

The specific surface area, measured according to the BET method, is 380 m2 / g.

The concentration of milliequivalents H + per gram is z, s.lo'1.

Fig. 1 shows the X-ray diffraction spectrum of the product according to this example.

Example 5 This example is intended to illustrate the preparation of a porous crystalline silica, designated TRS-20, in whose crystal lattice aluminum has been introduced as a modifying element as a replacement for silicon. The production of this silica has been carried out without an inorganic alkaline base. The only alkaline cations may come from traces of impurities in the reactants used.

Using the same procedure as in Example 1, 40 g of tetraethyl orthosilicate, a solution of 100 ml of Al (NO 3) 3,9H 2 O in 50 ml of absolute ethanol, 50 ml of a 40% (w / w) aqueous solution of tetrapropylammonium hydroxide (obtained tetrapropylammonium bromide and moistened silver oxide) to give a product free of alkaline inorganic bases. The mixture is kept at 155 ° C for 10 days.

X-ray analysis shows that the sample, dried at 120 ° C, has crystalline properties.

To be used as a catalyst, the product is heated to 550 ° C in air for 16 hours and then washed many times with distilled water containing dissolved ammonium ac- _.___..... ......__ ___: soon l0 15 20 25 After which the solid material is reheated to 550 ° C for 6 hours.

Chemical analysis shows that the product obtained has a composition of 96.1% SiO2, 0.3% Al2O3 and 0.01% Na2O, all by weight. Weight loss on heating to 1200 ° C is 3.59%. The molar ratio SiO2 / Al2O3 is 544.

The specific surface area, determined according to the BET method, is as high as 500 m2 / g. The concentration of H + ions per gram is 4.7.10. Example 6 This example is intended to show the production of porous crystalline silica called TRS-57 in whose crystal lattice is 1 meq. aluminum has been introduced as a modifier. In the production of this silica, triethanolamine has been used. 80 g of tetraethyl orthosilicate, 80 mg of Al (NO 3) 3.9H 2 O are dissolved in 50 ml of absolute ethanol, a solution of 27 g of triethanolamine in 50 ml of distilled water is reacted using the procedure described in Example 1.

Therefore, 7 g of sodium hydroxide are added and the glass vessel is placed in an autoclave and kept there at 94 ° C for 7 days.

The proact, dried via 120 ° C, is the X-ray crisis.

The X-ray diffraction spectrum of this product is shown in FIG. 2.

Chemical analysis on the sample, heated to 550 ° C, gives the composition 96.2% SiO2, 0.2% Al2O3 and 0.05% Na2O, all by weight. Weight loss on heating to 100 ° C is 3.55%.

The molar ratio SiO 2 / Al 2 O 3 is 816. The specific surface area, measured according to the BET method, is 344 m2 / g, and the concentration of H + meq per gram is 1.5.5 ~ 1.

Example 7 (Comparative Example) This example is intended to illustrate the absence of dehydrating catalytic properties of the modified crystalline silica, TRS-22, prepared according to Example 1 but containing sodium cations, so that the concentration of protonic milliequivalents per g of sample is as low as 4, l.l0-4.

The formation of dimethyl ether of methanol has been chosen as an exemplary dehydration reaction. 10 15 ZQ 25 30 35 7905453-2 _ ll An electrically heated tubular reactor with an inner diameter of 8 mm is charged with 4 ml (= 2 g) of catalyst in a grain size corresponding to a mesh size between 0.18 and 0.60 mm.

The catalyst is first heated to 500 ° C for 2 hours in a stream of nitrogen, so that absorbed water is removed. »Methanol is then fed at a space velocity of 1.5 g / g per hour with an oven temperature of 275 ° C, which is then raised to 400 ° C. Samples of the effluent downstream of the reactor were analyzed by gas chromatography. The analysis shows that the effluent from the reactor contained only methanol at both the indicated temperatures.

Example 8 (Comparative_Example) This example is intended to illustrate the absence of hydrating properties of modified crystalline silica TRS-23 as prepared in Example 3 without thorough washing, so that the concentration of protonic millivivalent per gram of catalyst is as low as 1.1. .l0'6.

The procedure was carried out as in Example 7 with the apparatus indicated therein, the reactor being charged with 4 ml (= 2.8 g) of catalyst, the grain size of which corresponds to a mesh size between 0.018 and 0.60 mm and the catalyst was heated for 2 hours at 500 ° C in a stream of anhydrous nitrogen.

At temperatures of 24,000, 300 ° C and 400 ° C, methanol was fed in at a space velocity of 1.75 g / g per hour.

In all three cases there was no dimethyl ether in the effluent from the reactor but only the methanol fed.

Example 9 This example is intended to illustrate the excellent catalytic dehydration properties of the modified crystalline silica TRS-22 as prepared according to Example 1 and with a concentration of protonic milliequivalents per gram of 1, 10, 10 -1.

In the same manner as described in Example 7, the reactor was charged with 5 ml (= 3.5 g) of catalyst in a grain size corresponding to a mesh size between 0.18 and 0.60 mm.

After heating for 2 hours under anhydrous nitrogen stream to remove adsorbed water, methanol was fed in at a space velocity of 1.5 g / g per hour at reactor temperatures of 20 ° C and 2 ° C.

° Analysis of the reactor effluent, which consisted of dimethyl- * Poor QUALW 10 15 20 25 30 35 per gram of catalyst is 4,1,10 '. 7905453-2 12 ether, unreacted methanol and water, however, ascertaining the presence of by-products detected by gas chromatography, gave results as shown in the following Table 1.

It appears from this that the crystalline silica according to the present invention has excellent dehydration activity with higher conversion percentages than those described in the Swedish patent application 7513085-6, regarding active aluminas, which have been treated with silicon compounds.

It is sufficient here to note that by working with Tas-22 at 2so ° c one at 2ss ° c one obtains at a space velocity of 1.5 g / g per hour a conversion of methanol which is equal to the respective higher than those achievable at 300 ° C and at a space velocity of 1 g / g per hour on active alumina treated with silicon compounds.

TABLE 1 Dehydration of methanol to dimethyl ether Catalyst: TRS-22 Temperature, OC 25006 265 ° C Pressure, kPa 100 100 Space velocity g / g per hl, 1.5 1.5 'conversion of cH3on with 1 ~% 82.4 88.1 Examples (Comparative Example) This example is intended to show the conversion of dimethyl ether to hydrocarbons, with particular attention to light olefins, over modified crystalline silica TRS-22 as prepared according to Example 1 and containing sodium cations, so that the concentration of ïrotonic milliequivalents An electrically heated tubular reactor with an inner diameter of 8 mm is charged with 2 ml (= 1g) of a catalyst with a grain size corresponding to a mesh size between 0.18 and 0.60 mm.

The catalyst is first heated to 550 ° C for 2 hours in a stream of nitrogen to remove any absorbed water.

Then dimethyl ether is fed in gaseous form, while all pipes are heated to prevent condensation. Downstream of the reactor, a sampling apparatus is installed, which is properly heated and transfers effluent from the reactor to a gas chromatograph, where complete analysis of the reaction products is performed.

As far as the calculation of the conversion is concerned, it may be mentioned that the methanol formed by partial hydration of dimethyl ether is considered as unreacted product, so that the molar conversion is attributed to the dimethyl ether which has been converted to hydrocarbons, carbon monoxide and carbon dioxide. The molar selectivities of the products are based on the number of moles of dimethyl ether converted to the given product in relation to the total number of moles reacted.

The results thus obtained are shown in Table 2. This clearly shows that the catalyst in question is neither very active nor highly selective, in that considerable amounts of carbon monoxide, carbon dioxide and methane are formed.

TABLE 2 Conversion of dimethyl ether to hydrocarbons Catalyst: TRS-22 Sample Temp. Print Ryndhas- Transformation Selectivity in the products, no. oc. kPa tighet nol-% nol-% + g / g / h co + ooz + czi4-czn4-c3ne-c4 l 373 100 0.65 2.3 5.0 14.9 30, l 50.0 475 100 0, 97.05 10.9 6.5 26.1 56.5 Example 11 This example is intended to show the conversion of dimethyl ether to hydrocarbons, with particular attention to light olefins, with modified crystalline silica TRS-22 as prepared according to Example 1 and with a concentration of 1.5, 10-10 proton milliequivalents per g of sample.

In the same manner as with the apparatus of Example 9, the reactor was charged with 3 ml (= 1.5 g) of catalyst in a grain size corresponding to a mesh size between 0.18 and 0.60 mm.

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

The results obtained are shown in Table 3. Comparison with Table 2 clearly shows that the efficiency of the catalyst changes positively with the acidity. 10 7905453-.2 14 TABLE 3 Conversion of dimethyl ether to hydrocarbons Catalyst: TRS-22 Sample Tenp. Print Fymdhas- Cnwandling, Sehäd fi vitet in the products, no. oc kPa tighet npl-% nol-% + 9 975 Cx "305- -100 2.7 38.8 0-5 30.1 24,3 05,1 2 i 335 100 2.7 87.9 0.5 23.0 19.9 55_5 3 365- 1oo 0.7. 97.3 0.5 19.0 1s .s 61.7 -4 365 100 6.7 37.0 0.5 23.2. 19.7 56.6 5 # 85 100 6-7 _ 97.1 0.5 1s.3 18.7 61.9 6 485- 100 8-7- 87.1 o.5 2o.1 18.2 61.2 7 1:40 100 9.0 92.1 0.5 15.5 15.2 57.3 Example 12 5 ml of aluminum-modified silica TRS-20, prepared as described in Example 5, is impregnated with an aqueous solution of H 2 PtCl 6 in such a way that the content of Pt in the catalyst is 0.2% by weight.

The platinum is reduced to the elemental state at 600 ° C in hydrogen stream and introduced into an electrically heated tubular reactor with an inner diameter of 20 m.

The ability to clean exhaust gases from a motor vehicle was tested with two typical reactions, ie. oxidation of propylene to carbon dioxide and oxidation of carbon monoxide to carbon dioxide.

Sample A The feed gases, which consisted of 800 ppm propylene, 8% oxygen and the remainder nitrogen, were preheated to 120 ° C and passed over the catalyst at a gas space velocity of 50,000 h_l.

Propylene was converted to 99%. The same gas mixture, preheated to 90 ° C, is fed to the catalyst at a gas space velocity of 20,000 h'l, whereby a conversion of 99% propylene is obtained.

Sample B Feed gases, consisting of 2.5% CO, 8% O2 and the residual nitrogen, are preheated to 80 ° C and allowed to pass the catalyst at a flow rate of 20 .000 n "l of CO is obtained, whereby conversion of 59 The same gas mixture, preheated to the same temperature, is fed to the catalyst at a space velocity of 50,000 h ~ 1, whereby CO is converted to 99% The above temperatures, i.e. 80 ° C and 120 ° C, must, in order to to be fair, are considered exceptional, as the best commercial catalysts used in catalytic silencers perform the same conversion conditions for propylene and carbon monoxide at the same space velocities, but at temperatures never below 1 ° C.

Example Gel 130 This example illustrates the preparation of the zeolite ZSM-5 using triethanolamine.

A vessel of refractory glass, kept in a CO2-free atmosphere, is charged with 60 g of Al (NO3) 3.9H2O dissolved in 400 ml of 95% ethanol, after which 600 g of tetraethylorthosilicate are added with stirring. Once the solution is ready, add 200 g of triethanolamine dissolved in 400 ml of distilled water and heat the mixture, still stirring, to 60 ° C.

After a further 30 minutes, a solution of 13 g of NaOH in 200 ml of distilled water is added and after a further 30 minutes, an additional 22 g of NaOH (a total of 35 g of NaOH) dissolved in 400 ml of water are added. A solid gel is formed, initiating vigorous stirring which is maintained for a few hours, at the same time as the temperature is raised to 90 ° C so that all ethanol is removed, both that which has been added to the reaction and that which is formed during the hydrolysis. At this stage, the reaction mixture is transferred to a 3-liter stainless steel autoclave and hydrothermal treatment at 195 DEG C. is started and maintained for 24 hours. The product obtained is then allowed to cool to room temperature, collected on a filter, washed many times with very hot distilled water and dried at 120 ° C. The solid is then heated to 550 ° C for 16 hours and transferred to the H + form by repeated exchange in the hot state (95 ° C) with ammonium acetate or nitrate, after which the material is reheated to 550 ° C for 6 hours.

POOR QUALITY 1905453-2 '16 X-ray diffraction spectrum corresponds to that given in Table I of U.S. Pat. No. 3,702,886.

Example 14 Using the same procedure as in Example 13, 880 g of tetramethylorthosilicate, 120 g of Al (NO 3) 3 .9H 2 O, 400 g of triethanolamine, previously dissolved in 800 ml of water, 70 g of NaOH in 700 ml of water are reacted and the mixture is worked up. to a volume of about 9 l by adding distilled water with vigorous stirring. The mixture is concentrated at 80 ° C for about 30 hours until the volume of liquid is reduced to about 5 l. The hydrothermal treatment is carried out for 8 days at 109 ° C in a stainless steel autoclave equipped with a stirrer. .

The X-ray diffraction spectrum corresponds to the spectrum of ZSM-5 and the specific surface area is 380 m2 / g.

The SiO 2 / Al 2 O 3 ratio is 38.

Example 15 9.6 g of sodium aluminate and 10 g of potassium hydroxide are dissolved in 200 ml of water. To the clear solution is added 208 g of triethanolamine, dissolved in 1000 ml of water. The solution thus obtained is allowed to stir under a layer of inert gas for 2 hours at 8000. Then 40 g of potassium bromide, dissolved in 150 ml of water, are added as crystallization promoter.

Then slowly add 345 g of colloidal silica of the Ludox type (40% SiO2), dissolved in 1500 ml of water. The gel formed is allowed to age for 24 hours at 90 ° C under inert gas stream.

The gel thus treated is then crystallized in a stainless steel autoclave for 10 days at 98 ° C.

The procedure set forth in Example 13 is completed and the zeolite ZSM-5 has thus been obtained.

Claims (13)

n 7905453-2 PATENT REQUIREMENTS Aluminum-modified silica, characterized in that it has a porous crystalline structure and a specific surface area greater than 150 m2 / g and has the following general formula: 1 Si. (0.0012 - 0, G050 ) Al.Oy where Y is from 2.0018 to 2.0075. Process for the production of an aluminum-modified silica according to claim 1, characterized in that in a water, alcohol or hydroalcoholic solution a derivative of silicon and a derivative of aluminum are reacted with a substance having a crosslinking or climbing agent. effect, possibly with the addition of one or more mineralizing agents and possibly an inorganic base, allows the whole to crystallize in a container for a period of from a few hours to several days at a temperature of from 100 ° C to 220 ° C, allow the whole to cool and, after filtration and drying, heat in air at a temperature between 300 ° C and 700 ° C for a period of from 2 hours to 24 hours, optionally washing with boiling distilled water containing a ammonium salt dissolved therein and reheated in the same manner as above. 3. A method according to claim 2, characterized in that the derivative of silicon is selected from silica gel, regardless of how they are formed, and tetraalkyl orthosilicate. 4. The method of claim 3, wherein the tetraalkyl orthosilicate is tetraethyl orthosilicate or tetramethyl orthosilicate. 5 5. A method according to claim 2, characterized in that the derivative of aluminum is a salt and especially aluminum nitrate or aluminum acetate. 6. A method according to claim 2, characterized in that the substance having a bridging or climbing effect is selected from tertiary amines, amino alcohols, amino acids, polyalcohols and quaternary ammonium bases. POOR QUALIT '7905453-2 1% A method according to claim 6, characterized in that the quaternary ammonium base is a tetraalkylammonium NR 4 OH, wherein R is an alkyl radical having from 1 to 5 carbon atoms, or tetraarylammonium, NA 4 OH, wherein A is a phenyl or an alkylphenyl radical . 8. A method according to claim 2, characterized in that the mineralizing agent is selected from hydroxides and halides of alkali metals and alkaline earth metals. 9. A method according to claim 8, characterized in that the mineralizing agent is selected from LiOH, NaOH, KOH, Ca (OH) 2, KBr, NaBr, NaI, CaI2, CaBr2. 10. A method according to claim 2, characterized in that the inorganic base is selected from hydroxides of alkali metals and alkaline earth metals as well as ammonia. 11. ll. A method according to claim 10, characterized in that the inorganic base is NaOH, KOH, or Ca (OH) 2. 12. A method according to claims 2, 6, 7, 10 and 11, characterized in that the amounts of inorganic base and / or substances with bridging or climbing effect are smaller than the stoichiometric amounts with respect to silica. 13. A method according to claim 12, characterized in that the amounts of inorganic base and / or substances having a bridging or climbing effect are between 0.05 and 0.50 mol per mol of silica.