CS262430B2 - Method of alkylating aromatic hydrocarbons or four-carbon-atoms hydrocarbons,olefins and/or saturated hydrocarbons - Google Patents

Description

The invention relates to a process for the alkylation of aromatic hydrocarbons or hydrocarbons having four carbon atoms, olefins and / or saturated hydrocarbons to alkylaromatic hydrocarbons or hydrocarbons having a high octane number, in the presence of an aluminum modified silica catalyst.

Many catalysts are known in the art for a variety of alkylation reactions, including silica-based and alumina-based materials prepared synthetically or freely in nature.

These materials also include substances, called zeolites, which are suitable as adsorbents, and molecular sieves, which have catalytic properties which can be used in a wide variety of reactions such as alkylation, isomerization, hydration, cracking, hydrogenation cracking and the like. alike.

In these materials, the alumina content is within wide limits with respect to the silica. The maximum ratio of silica to alumina is 100: 1, but this ratio is usually much lower and preferably lies around 2.

In order for these materials that contain aluminum in a tetrahedron configuration to replace silicon, the electrically neutral must contain cations capable of balancing charges due to the presence of aluminum atoms arranged in a tetrahedron configuration.

The protonic acidity of these zeolites can be derived from the hydrogen atoms that have been introduced as a replacement for the cations. On the other hand, the crystalline silicas, by virtue of their intrinsic character, do not contain protonic charges and therefore cannot have an acidic character unrelated to silicic acid.

Many types of crystalline silica are known in the prior art, starting with crystallobalite and ending with tridvmit and keatite, and in addition many other silica-based substances are known which are prepared by methods known in the literature. For example, according to Heidemann, see. Beitr. Min. Petrog. 10, 242, 1964, can be obtained by reacting an amorphous silica with 0.55% KOH at 180 C ^e, which was carried out for two and a half days, crystalline silica, called X silica having a specific surface area of about 10 m ² / g and low stability, as it changes to crystallite in about five days and then to quartz. Flanlgen et al. discloses, in Nature, 271, 512, 1978, a process for obtaining a crystalline silica, called silicalite, with a large specific surface area, and because of the hydrophobic nature of this material, it has been proposed for use in the purification of water contaminated with organic substances.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a process for the alkylation of aromatic hydrocarbons or hydrocarbons having four carbon atoms, olefins and / or saturated hydrocarbons to alkylaromatic hydrocarbons or hydrocarbons having a high octane number which is effectively catalysed by crystalline silica modified aluminum. silica. It is also an object of the invention to modify the acidity and hence the catalytic activity of this material, which would be suitably modified for the purpose of a particular reaction.

According to the present invention, the process for the alkylation of aromatic hydrocarbons or hydrocarbons having four carbon atoms, olefins and / or saturated hydrocarbons to alkylaromatic or high octane hydrocarbons is carried out in the presence of an aluminum-modified silica based catalyst which: it has a porous crystalline structure, a specific surface area of more than 150 m ² / g and corresponds to the general formula

Si. (0.0012 to 0.0050] Al. _{Y y} where y ranges from 2.0018 to 2.0075, wherein the molar ratio of silica to alumina SiO 2: Al 2 O 3 ranges from 38 to 816 for this compound at a temperature ranging from 250 to 500 ° C and a pressure ranging from 1.5 d to 2.5 MPa.

An advantage of the process of the present invention is the large specific surface area of the aluminum modified silica based material used, which is very stable during the alkylation and can be easily regenerated and reused.

According to the present invention, materials having a high molar ratio of silica to alumina are used but not zeolites, since a minimal amount of aluminum contained therein cannot provide a crystalline aluminosilicate structure.

On the other hand, the materials used clearly differ from the crystalline silica in that the introduction of a small amount of aluminum leads to large changes in the acidity of the material.

The above aluminum modified silica materials have a protonic acidity equal to or greater than the protonic forms of zeolites, while retaining a very high structural stability of crystalline silica, an opposite trend to that observed with protonated forms of zeolites type A, X and Y (with the sole exception of mordenlt materials), which are relatively unstable and tend to switch easily to

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With a more stable mixture of silica and alumina.

As such, silica-alumina mixtures (silica-alumina) have somewhat lower acidity. For example, commercially available mixtures of silica and alumina containing 25% by weight alumina have a concentration of the order of 1.

. 10 ' ³ mekv. H ⁺ per gram of catalyst.

Furthermore, it has been unexpectedly found according to the invention that by appropriate dosing of the amount of aluminum in the material, its acidity can be adjusted to match the particular range required by the type of reaction for which the material is intended.

More or less crystalline water may be present in the aluminum modified silica based material of the present invention having the above general formula, depending on the method of preparation of the material or the crystalline water. at the calcination temperature.

This aluminum-modified silica-based material can generally be used as follows. The silicon derivative and the aluminum derivative are reacted in an aqueous, alcoholic or aqueous-alcoholic solution with a clathrate or archive former, optionally adding one or more mineralization agents to promote crystallization and optionally an inorganic basic compound. The resulting mixture is allowed to crystallize in a sealed environment for a period which may generally range from a few hours to many days, at a temperature of from 100 to 220 ° C, preferably at a temperature of from 150 to 200 ° C, for a period of time 1 week. The product is then allowed to cool and, after filtration, dried and calcined at a temperature in the range of from 300 to 700 ° C, preferably at 550 ° C, for a period of from 2 to 24 hours. The material is then washed to remove any ion-exchangeable cationic impurities present in boiling distilled water containing dissolved ammonium salt, nitrate or acetate may also be advantageously used, and then repeated by the above calcination.

The silicon derivatives may be selected from the group consisting of any silica-based material, for example silica gel (regardless of the method of its preparation) and tetraalkyl orthosilicates such as tetraethyl orthosilicate and tetramethyl orthosilicate.

The aluminum derivatives are preferably selected from the group consisting of aluminum salts such as nitrates and acetates.

Substances having an archive-forming or clathrate-forming effect may be selected from the group consisting of tertiary amines, aminoalcohols, amino acids, polyalcohols and quaternary ammonium bases such as tetraalkylammonium bases of the general formula

NRiOH in which R represents an alkyl group having 1 to 5 carbon atoms, or tetraarylammonium bases of the formula NA 4 OH, wherein A is a phenyl or alkylphenyl radical.

The role of clathrate or archive-forming agents is to contribute to the desired crystalline structure with pores of a defined size, and therefore these are composed of molecules of appropriate size.

The mineralization additives may be selected from the group of alkali or alkaline earth metal hydroxides or halides, such as lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, potassium bromide, sodium bromide, sodium iodide, calcium iodide and calcium bromide.

The added inorganic basic compound may be selected from the group consisting of alkali or alkaline earth metal hydroxides, preferably sodium hydroxide, potassium hydroxide and calcium hydroxide, and ammonia.

The amount of inorganic basic compound and / or clathrate used is generally less than the stoichiometric amount required with respect to the silica in the process for preparing these aluminum-modified silica materials, and is preferably in the range of 0.05 to 0 mol. , 50 mol per mol of silica.

The aluminum-modified silica-based materials thus obtained are characterized by protonic type acidity, which can be modified by varying the introduced substitution cation. For pure silica, the number of milliequivalents of hydrogen ions is 1.10 ^-3 per gram of material, which acidity can be increased by the introduction of aluminum as described above up to a value of ^1.10-1 milliequivalents of hydrogen ions per gram of material.

The materials obtained as described above, which are used as catalysts for the process according to the invention, are characterized by a defined crystalline structure and a large specific surface area which is greater than 150 m ² / g and generally reaches values of 300 to 500 m ² / g.

The presence of aluminum thus strongly modifies the acidity of the silica and has a beneficial effect on the formation of crystalline materials whose spectra are either very similar to those reported in the literature for crystalline silica called silicalite (see Nature, 271, 512, 1978) or different.

The aluminum-modified silica can be used for the alkylation of aromatic hydrocarbons or hydrocarbons having four carbon atoms, olefins and / or saturated hydrocarbons according to the present invention, either in the form in which they are prepared or dispersed on a more or less inert carrier which may have large or small specific surface and porosity.

The purpose of the carrier material is to increase the physical stability and mechanical resistance and, if appropriate, the catalytic properties of the material. Any of the known methods can be used to prepare the supported materials.

The amount of carrier material in the final composition may be 1 to 90% by weight, preferably 5 to 00% by weight.

Examples of preferred carrier materials for this purpose include various clays, silica, alumina, diatomaceous earth, a mixture of silica and alumina (silicoalumine), and the like.

The aluminum-modified silica can be used not only for the purposes of the present invention but also for other reactions such as: alkylation of toluene with methanol to xylene, predominantly p-xylene, disproportionation of toluene to form predominantly p-xylene, conversion of dimethyl ether and / or methanol or other alcohols to hydrocarbons such as olefins and aromatics, cracking, and hydrogenation cracking, isomerization of normal paraffins and naphthenes, polymerization of compounds containing olefinic or acetylene bonds, reforming, isomerization of polyalkyl-substituted aromatics such as o-xylene, disproportionation aromatic hydrocarbons, separating ethylbenzene from other C 6 aromatic hydrocarbons, hydrogenation and dehydrogenation of hydrocarbons, and methanization.

In the following, some practical examples of the process of the present invention will be given, together with examples of the preparation of the aluminum modified silica based material used in the process of the present invention.

Example 1

This example illustrates the activity of a catalyst designated TRS-22, the preparation and characteristics of which are given in Example 8 below (1.5 × 10 ^-1 meq H ⁺ / g) in the alkylation of benzene with ethylene.

According to this embodiment, 1.2 milliliters (0.8 grams) of a TRS-22 catalyst having a particle size ranging from 600 to 300 μΐη was charged to an electrically heated tubular reactor having an internal diameter of 8 millimeters. The benzene was fed through the metering pump first to the preheating zone where it was mixed with a preselected ethylene flow rate and then to the reactor. The reaction products were analyzed by gas chromatography. The results obtained are shown in Table 1 below.

TABLE 1 Benzene alkylation with ethylene catalyst: TRS-22, pressure: 2 MPa, liquid phase space velocity: 14 h ¹ , C6H0: C2H4 molar ratio = 7

Time Temperature Ethylbenzene content Diethylbenzene content Conversion (h) (° C) in product (% mole) in product (% mole) ethylene (%)

10 440 13.8 1.50 100.0 50 440 13.7 1.55 100.0 100 ALIGN! 440 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

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Example 2

In this example, the catalyst regeneration process will be illustrated.

The catalyst designated TRS-22 used in the procedure of Example 1 was regenerated after 400 hours of operation for 5 hours at 550 ° C in a suitably conditioned stream of air. After completion of the recovery system for 1 hour, passed through du ^ magnesium, OZ _C was performed also at tpplotě 55q ° C, then the reaction was resumed as in Example 1 under the conditions indicated.

The results obtained are shown in Table 2.

TABLE 2 Alkylation of benzene with ethylene

Catalyst: regenerated TRS-22, pressure: 2 MPa, liquid phase space velocity:

h ¹ , molar ratio CeH 5: C ² H ⁴ = 7

Time Temperature Ethylbenzene content Diethylbenzene content Conversion (h) (° C) in product (% mole) in product (° / o mole) ethylene (%)

10 440 13.7 1.55 100.0 50 440 13.6 1.40 97.6 100 ALIGN! 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

Example 3

In this exemplary embodiment, the activity of a catalyst designated TRS-0, the preparation process and characteristics of which will be given in Example 9, in alkylating benzene with ethanol will be illustrated.

1.2 milliliters (0.8 grams) of catalyst having a particle size of 600-300 μπι was charged to an electrically heated tubular reactor having an internal diameter of 8 millimeters. The reaction mixture consisting of benzene and ethanol in a 5: 1 molar ratio was then fed through the metering pump, first to the preheating zone and then to the reactor.

This reaction was conducted at 440 ⁱⁿ C, while the reaction products were analyzed by gas chromatography. The results obtained are shown in Table 3 below.

TABLE 3 Alkylation of benzene with ethanol

Catalyst: TRS-0, temperature: 440 ° C, pressure: 2 MPa, liquid phase space velocity:

h “ ¹ , molar ratio ΟθΗθ: C2H5OH = 4

Time Ethylbenzene content Diethylbenzene content Conversion of plant (h) in product (% mole) in product (° / o mole) C2H5OH (%)

50 19.0 1,2 100 ALIGN! 100 ALIGN! 19.0 1,2 100 ALIGN! 150 19.0 1,2 .in 100 ALIGN! 200 19.0 1,2 100 ALIGN! 300 19.0 1,2 100 ALIGN! 400 19.0 1,2 100 ALIGN!

if

Example 4

This example illustrates the activity of a catalyst designated TRS-57, the preparation process and characteristics of which are given in the following Example 13, in the alkylation of benzene with ethylene.

In this example, the reaction was carried out in a fixed bed tubular reactor having an internal diameter of 8 millimeters with electric heating. 1.2 millimeters (0.85 grams) of catalyst having a particle size ranging from 600 to 300 µm were introduced into the reactor. Benzene was then fed through the metering pump first to a preheating system (where the benzene was mixed with a preselected flow rate of ethylene) and then to the reactor. The reactor effluent was analyzed by gas chromatography. The results obtained are shown in Table 4 below.

TABLE 4

Alkylation of benzene with ethylene

Catalyst: TRS-57, and pressure: 2 MPa, temperature: 440 ^C, C, space velocity of the liquid phase: 14 h ^_I molar ratio CeHe: C2H4 = 7

Time Amount of ethylbenzene Amount of diethylhenzene Conversion traffic (h) in product (% mole) in product (% mole) ethylene (%) 10 13.9 1.35 100.0 50 13.9 1.35 100.0 100 ALIGN! 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 11.3 0.00 78.9 Example ί 5 After regeneration, re-used for alkylation of benzene e- In this example, the same thylene. From the values given in the following analyzer, which was used for the alkylation of ben- table. 5, how easy- zene with ethylene in Example 4, designated regenerate this catalyst TRS-57 undergoes in-situ regeneration when which is one of the advantages of the this one regeneration was carried out of the present invention. air separation, which was diluted with nitrogen at temperature 500 ° C. TABLE 5 Alkylation of benzene with ethylene Catalyst: regenerated TRS-57, pressure: 2 MPa, temperature: 440 ° C, room temperature speed liquid phase: 14 h ^_1 , molar ratio ΟθΗθ: C2H4 = 7 Time Ethylbenzene content Diethylhenzene content Conversion traffic (h) in product (° / o molar) in product (° / o molar) ethylene (%) 10 14.0 1.30 100.0 50 13.9 1.35 100.0 100 ALIGN! 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

Example

In this exemplary embodiment, the activity of a catalyst designated TRS-57, the preparation process and characteristics of which will be shown in Example 13, in alkylating benzene with ethanol will be illustrated.

The reaction of this example was carried out by placing 1.2 milliliters (0.85 grams) of catalyst having a particle size in the range of 600 to 300 μία into an electrically heated fixed bed tube reactor. The reaction mixture containing benzene and ethanol was fed through the metering pump, first into the preheating zone and then into the reactor. The output stream was analyzed by gas chromatography. The results are shown in the following table. 6.

TABLE 6

Alkylation of benzene with ethanol

Catalyst: TRS-57, pressure: 2 MPa, temperature: 440 ° C, liquid phase space velocity: 10 h ^-1 , molar ratio ΟΰΗθ: C 6 H 6 OH = 5

Time traffic (hj Ethylbenzane content in product (° / o molar) Diethylbenzene content in the product (% mole) CyHsOH Conversion (%) 50 18.8 1.3 100 ALIGN! 100 ALIGN! 19.0 1,2 100 ALIGN! 150 18.8 1.3 100 ALIGN! 200 19.0 1,2 100 ALIGN! 250 19.0 1,2 100 ALIGN! 300 19.0 1,2 100 ALIGN! 400 19.0 1,2 100 ALIGN!

A specific feature of the process of the present invention is the use of aluminum modified silicas as catalysts for the alkylation of Cd hydrocarbons, olefins and / or paraffins to hydrocarbons having a high octane number. As mentioned above, these silicas are porous and have a specific surface area greater than 1.50 m ² / g, the general formula of which is given in the description.

The following example illustrates this specific applicability of the aluminum-modified silica of the present invention.

EXAMPLE 7 A porous crystalline silica was used as the catalyst of this embodiment, the preparation and characteristics of which will be given in the following Example 12, in which aluminum has been introduced into the crystal lattice as a replacement for silicon.

A small reactor was charged with 3 milliliters of catalyst (1.9 grams) having a particle size ranging from 600 to 300 µm, and the above reaction was performed. The results obtained and the conditions of this procedure are shown in Table 7 below.

For alkylation of isobutane with normal butones

TABLE 7

Pressure: 2 MPa, molar ratio of isobutene to n-butene: 15

Temperature Spatial Alkylation related Product composition (° C) speed (h ^-1 ) to butenes (° / o)

250 1.3 100

350 1.3 100

350 5.0 90

Example 8

This example will illustrate the process of preparation and characterization of crystalline porous silica designated TRS-22, into whose crystal lattice aluminum has been introduced as a replacement for silicon.

In a glass vessel (pyrex glass), which was kept under a constant nitrogen atmosphere, was charged 80 grams of tetraethyl orthosilicate, which was heated to 80 ° C with stirring. Then a solution of 20 grams of tetrapropylammonium hydroxide (obtained from tetrapropylammonium and moistened silver oxide to obtain a product free of inorganic alkaline bases) in 80 ml of distilled water was added, with 90% of the isoparaffins being stirred at 80 ^° C. (- about 20% aromatics about 50% isoparaffins -) - about 50% aromatics about 70% isoparaffins + about 30% aromatics to a homogeneous and clear mixture, which took about 1 hour.

80 mg of aluminum nitrate Al (NO3), 1.9 H / O, dissolved in 50 ml of absolute ethanol, were then added.

After this addition, a compact gel was formed almost immediately, to which distilled water was added to a total volume of 200 ml, and then stirring was started if necessary. The mixture was boiled to complete the hydrolysis and distillation of all ethanol, i.e. both added and released by hydrolysis.

These phases lasted for 2 to 3 hours, the gel gradually being converted to a white crystalline powder which was a precursor of modified crystalline silica.

The mixture was then made up to distilled

1 ml of water was added to a volume of 150 ml and then the glass container was placed in an autoclave and left at 155 ° C for 7 days. After cooling, the resulting solid odstřecTována 15 minutes at a speed of 10000 min ^-1, then was resuspended in distilled water and centrifuged again and the washing step was repeated four times. The product was dried in an oven at 120 ° C and was found to be X-ray crystalline.

Chemical analysis of a sample dried at 120 ° C revealed the following composition:

SiO2 99.52 % weight A12O3 0.24 % weight NaaO 0.22 % weight K2O 0.02 % weight.

The general formula of the product was:

i Si. (0.002 8 Al}. O _y.

The loss on ignition at 1100 ° C was 16.6% and the molar ratio of SiO 2: Al 2 O 3 = 704.

The alkali metals present in the final product were derived from the reactants and glass, since they were not separately added. To remove the alkaline impurities present, the final product can be calcined at 550 ° C for 16 hours in an air stream and then repeatedly washed with boiling distilled water containing dissolved ammonium acetate and then calcined for 6 hours at 550 ^{° C.} C.

The BET specific surface area for this product was 444 m ² / g, and the proton concentration per gram of sample was 1.5. 10 ^_1 meq / g.

Example 9

In this example, a process for preparing a porous crystalline silica designated TRS-0 will be illustrated in which traces of aluminum have been introduced into the crystal lattice as a replacement for silicon.

In a glass flask (pyrex glass) equipped with a reflux condenser and maintained under a nitrogen atmosphere, 40 grams of tetraethyl orthosilicate and 120 ml of a 20% aqueous solution of tetrapropylammonium hydroxide (by weight) were charged, and then the mixture was heated to boiling. In this way a transparent colorless solution was obtained, which was clear even after long reflux.

At this stage, 30 milligrams of aluminum nitrate A1 (NO3) 3.9 H2O was added and the liquid passed an 11a opalescent appearance, leaving a white powder as it continued to heat.

The mixture was heated at boiling for 6 days, allowed to cool, the solid filtered and washed with distilled water and then dried at 100 ° C.

The product thus dried at 100 ° C was crystalline by X-ray. The calcination was carried out for 16 hours at 550 [deg.] C. in an air stream, and then the product was washed repeatedly with boiling distilled water containing dissolved ammonium acetate. The solid was then calcined again at 550 ° C for 6 hours.

Chemical analysis of the product revealed the following composition:

SiOa 99.78% by weight

Al 2 O 3 0.20% by weight

Na 2 O-K 2 O 0.02% by weight.

The general formula of the product was:

Si. (0.002 4) Al.O _y.

The ignition loss at 1100 ° C for this product was 3.58% by weight, with the silica to alumina molar ratio of S1O2:

: Al2O3 = 816.

The alkali metal traces present in this product came from the reactants and glass, since these were not added separately. The specific surface area determined by the BET method was 420 m ² / g and the concentration of protons per gram of sample corresponded 1,9.10 ^_1 meq / g.

Example 10

In this example, a process for preparing a porous crystalline silica, designated TRS-23, was introduced into the crystal lattice of which aluminum was substituted for silicon, and tetraethylammonium hydroxide was used as the organic base.

In this example, as in Example 8, 80 grams of tetraethyl orthosilicate, 68 ml of an aqueous solution of 25% w / w tetraethylammonium hydroxide, 80 milligrams of aluminum nitrate AlfNO 3 were reacted. 9 H2O dissolved in 50 ml of absolute ethanol and 2 grams of sodium hydroxide pellets dissolved in 10 ml of distilled water were left at 155 ^{C for} 18 days.

This product, dried at 120 ° C, was analyzed as X-ray crystalline. The concentration of protons per gram of sample (calcined at 550 ° C) was 1.1.10 ^-6 meq / g.

Chemical analysis, carried out with a carefully washed sample which was annealed at 550 ° C, revealed the following composition:

SiO2 99.77% by weight

Al 2 O 3 0.20% by weight

NaaO 0.03% by weight.

2 430

The general formula of the product was:

Si. (0.002 Al 4}. O _y.

The annealing of this product at 1100 ° C was 3.47% by weight, the silica to alumina molar ratio was 816, the BET specific surface area was 470 m ² / g and the proton concentration per gram of sample was 4. , 3 .10 ³ meq / g. Example 11

In this example, a process for preparing porous crystalline silica, designated TRS-19, was introduced into the crystal lattice of which aluminum was introduced as a replacement for silicon using tert-butylammonium hydroxide as the organic base.

In this example, as in Example 8, 50 grams of tetraethyl orthosilicate were reacted, a solution of 100 mg of aluminum nitrate A1 (NO;>) 3.9 H2O in 50 ml of absolute ethanol, a solution of 29 grams of tetrabutylammonium hydroxide (obtained from tetrabutylammonium bromide and wetted oxide) silver) in 120 ml of distilled water and 2 grams of sodium hydroxide, which was dissolved in 20 ml of distilled water.

The mixture was placed in an autoclave and left at 155 ° C for 16 days.

The product thus obtained, dried at 120 ° C, was X-ray crystalline. The concentration of protons per gram of sample (which was annealed at 550 ^Q C for 16 hours) .10 ^-4 corresponded to 4.5 meq / g.

Chemical analysis of a carefully washed product revealed the following composition:

SiO2 99.66% by weight

Al 2 O 3 0.31% by weight

Na.20 0,03% w / w.

The general formula of the product was:

Si. (0.003 6) Al.O _y .

The ignition loss at 1100 ° C for this product was 3.67% by weight, the silica to alumina molar ratio was 543, the BET specific surface area was 380 m ² / g and the proton concentration per gram of sample was 2.5.

. 10 ” ¹ meq / g.

Example 1 a d 12

In this example, a process for preparing a porous crystalline silica designated TRS-20, into whose crystal lattice aluminum has been introduced as a replacement for silicon, will be illustrated. The preparation of this silica was carried out without the use of an inorganic basic compound, whereby the possible presence of alkali cations originated from the trace impurities present in the reactants.

The procedure was as in Example 8, whereby 40 grams of tetraethyl orthosilicate, a solution of 100 milligrams of aluminum nitrate A1 (NO3) 3.9 H; O in 50 ml of absolute ethanol, 50 ml of an aqueous solution of tetrapropylammonium hydroxide (obtained from tetrapropylammonium bromide) and % moistened silver oxide) at a concentration of 40% by weight to obtain a product free of alkaline inorganic bases. The resulting mixture was left at 155 ° C for 10 days.

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

For use as a catalyst, the product was calcined for 16 hours in air at 550 ^C, C, and then repeatedly washed with boiling distilled water containing dissolved ammonium acetate, and finally the solid was again kalciinována 6 hours at 550 DEG C. ^Cl

Chemical analysis of the product thus obtained revealed the following composition:

SiO 3 99.68% by weight

Al 2 O 3 0.31% by weight

Na2O 0.01% by weight.

The general formula of the product was:

Sl. (0.003 6) Al. O _y .

The loss on ignition at 1100 ° C was 3.59% by weight, the silica to alumina molar ratio was 544, the BET specific surface area was 500 mVg, and the H ⁺ cation concentration per gram of sample was 4.7 meq. / / g.

Example 13

In this example, a process for preparing a porous crystalline silica designated TRS-57 will be illustrated in which aluminum has been introduced into the crystal lattice as a replacement for silicon. Triethanolamine was used in this preparation

The procedure was as in Example 8, whereby 80 grams of tetraethyl orthosilicate, 80 milligrams of aluminum nitrate Al (NO 3) 3.9 H2O dissolved in 50 ml of absolute ethanol and a solution of 27 g of triethanolamine in 50 ml of distilled water were reacted. 7 g of sodium hydrogen was then added and the glass vessel (pyrex glass) was placed in an autoclave where it was left for 7 days at 194 ° C.

The product thus obtained, dried at 120 ° C, was X-ray crystalline.

Chemical analysis of the product thus prepared, which was calcined at 550 ° C, revealed the following composition:

SiO2 99.74% by weight

Al 2 O 3 0.21% by weight

Na ₂ O 0.05% by weight.

The general formula of the product was:

Si. (0.002 4) Al. O _y .

The ignition loss at 1100 ° C was 3.55% by weight, the silica to alumina molar ratio was 816, the specific BET surface area was 344 m ² / g and the concentration of H ⁺ cations per gram of sample was 1.5. . 10 ^_1 meq / g.

Claims (1)

SUBJECT A process for the alkylation of aromatic hydrocarbons or hydrocarbons having four carbon atoms, olefins and / or saturated hydrocarbons to alkylaromatic hydrocarbons or hydrocarbons having a high octane number, characterized in that it is carried out in the presence of an aluminum modified silica based catalyst having a porous crystalline structure , a specific surface area of more than 150 m ³ / g corresponds to the general formula