CS257251B2 - Production method of the silicon oxide modified by alluminium - Google Patents

Abstract

Silicon oxide production process modified with porous crystalline aluminum structure, specific surface greater than 150 m ^ / g, of the general formula Si. (0.001 to 0.005%) Al. Oy ve which y ranges from 2,001 8 to 2.007 5, and with a silica molar ratio to alumina in the range from 38 to 816, is carried out by reacting the compound of silicon with an aluminum compound in the presence clathrate and optionally in the presence of a mineralizing agent and inorganic basic compounds. Mixture is allowed to crystallize in a closed environment for 5 to 20 days at 100 to 220 ° C, then filtered, dried and calcined, optionally washed and calcined again. The substances obtained can be used as catalysts for various reactions, especially alkylation.

Description

The invention relates to a process for the production of aluminum modified silica having a porous 2 crystalline structure, having a specific surface area greater than 150 m / g and having a molar ratio of SiO 2 Al 2 O 3 in the range of from 38 to 816.

A large number of silica and alumina substances are known in the art, some of which occur naturally and others are artificially produced.

They also include those commonly known as zeolites which are suitable as adsorbents and molecular sieves, and have good catalytic properties.

The alumina content of these materials in relation to the silica varies within wide limits. The maximum ratio of silica to alumina is 100: 1, but this ratio is usually much lower, preferably about 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 said tetrahedron configuration.

The protonic acidity of these zeolites can be derived from the hydrogen atoms that have been introduced as a substitute 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 different types of crystalline silica are known and used in the prior art, from crystalline to tridymite and keatite, and, in addition, many other materials prepared by processes that are described in detail in the technical literature. For example, according to Heidemann, see Beitr. Min. Petrog. 10, 242 (1964), can be obtained by reacting amorphous silica containing 0.55% by weight of potassium hydroxide at 180 ° C for two and a half days, a crystalline silica, called silica X, having a specific surface area of about 10 m / g and low stability, as it changes to crystallite in five days and then to quartz. Flanigen et al. discloses, in Nature, 271, 512 (1978), a process for obtaining a crystalline silica, referred to as silicalite, with a large specific surface area, and because of its hydrophobic nature, it has been proposed to use this material to purify water contaminated with organic substances.

It is an object of the present invention to provide a process for preparing crystalline aluminum-modified silica while maintaining unchanged stability of the silica, and thus to prepare a material which would be suitable as a catalyst or as a starting material for catalyst preparation.

It is a further object of the present invention to provide a process for preparing silica modified by introducing aluminum atoms that exhibits acidity and catalytic activity suitable for certain reactions.

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Substance of a process for producing aluminum modified silica having a porous crystalline 2 structure, having a specific surface area of more than 150 m / g and having a molar ratio of SiO 2 / Al 2 O 3 of from 38 to 816, which corresponds to the general formula

Si. (0.001 2 to 0.005 0) Al. 0 _y where y ranges from 2.001 8 to 2.007 5 comprises according to the invention in that the aqueous, alcoholic or aqueous-alcoholic solution, reacting the silicon compound from the group comprising silica and tetraalkylorthosilicate, an aluminum compound such as aluminum nitrate and aluminum acetate in the presence of a clathrate reagent selected from the group consisting of tertiary amines, aminoalcohols and tetraalkylammonium hydroxides containing from 1 to 5 carbon atoms in the alkyl moiety and triethanolamine, optionally adding one or more mineralizing agents and optionally inorganic basic compound.

The mixture is left to crystallize in a closed medium for 5 to 20 days at a temperature in the range of from 100 to 220 ° C, then allowed to cool and, after filtration and drying, calcined in air at a temperature in the range of 300 to 700 ° C for 2 hours. to 24 hours, optionally washed with boiling distilled water containing the ammonium salt and calcined again under the above conditions.

Unexpectedly, it has been found that materials having a high molar ratio of silica to alumina can be prepared but not zeolites, since the minimum amount of aluminum contained therein cannot provide a crystalline aluminosilicate structure.

On the other hand, these materials obtained by the process according to the invention are completely different from crystalline silicas in that large changes in acidity occur by the introduction of a small amount of aluminum.

The materials obtained by the process of the invention have a protonic acidity equal to or greater than the protonic forms of zeolites while maintaining a very high structural stability of crystalline silica, a trend opposite to that observed with the protonic forms of zeolites A, X and Y (the only exception being the mordenite group) ), which are relatively unstable and tend to switch easily to more stable mixtures of silica and alumina.

The silica-alumina mixtures as such have a somewhat lower acidity, for example a commercially available silica-alumina mixture containing 25% by weight alumina has a concentration of the order of 1.10 meq. H per gram of catalyst.

Furthermore, it has been found that, surprisingly, by appropriately dosing the amount of aluminum in the final product, the acidity of the product can be adjusted to suit the particular requirement of the kind of reaction for which the material is intended.

In a preferred embodiment, the tetraalkyl orthosilicate is tetraethyl orthosilicate and tetramethyl orthosilicate, and the preferred mineralizing agent is an alkali metal or alkaline earth metal halide selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, potassium bromide, sodium bromide, sodium bromide, sodium bromide, sodium bromide, sodium bromide, , calcium iodide or calcium bromide. The inorganic base is preferably an alkali metal and / or alkaline earth metal hydroxide and / or ammonia, with the most preferred alkali metal and alkaline earth metal hydroxides being sodium hydroxide, potassium hydroxide and calcium hydroxide.

Preferably, the amount of inorganic base and / or tetralkylammonium hydroxide or triethanolamine is less than the stoichiometric amount based on silica, preferably 0.05 to 0.50 moles per mole of silica.

The silica modified by the introduction of aluminum atoms has the general formula according to the invention:

Si. (0.001 2 to 0.005 0) Al. In which y ranges from 2.001 to 2.007 5. Depending on the calcination temperature, greater or lesser amounts of crystalline water may be present.

The following procedure can generally be used to obtain the aluminum modified silica of the invention. The silicon derivative and the aluminum derivative are reacted in an aqueous, alcoholic or aqueous-alcoholic solution with a clathrate or an archive-forming agent, optionally adding one or more mineralizing 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 be in the range of from a few hours to many days, at a temperature in the range of from 100 to 220 ° C, preferably in the range of from 150 to 200 ° C for one weekly. Thereafter, the product obtained is allowed to cool and, after filtration, dried and calcined at a temperature in the range of from 300 to 700 ° C, preferably at a temperature of about 550 ° C, for a period of from 2 to 24 hours. This is followed by washing to remove any ion exchange exchangeable cationic impurities boiling in distilled water containing dissolved ammonium salt, nitrate or acetate may also be advantageously used, and the above calcination may be repeated.

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 may preferably be selected from the group consisting of aluminum salts, for example, aluminum nitrate or aluminum ootane.

The clathrating agents may be selected from the group consisting of tertiary amines, aminoalcohols, amino acids, polyalcohols and quaternary ammonium bases such as tetraalkylammonium bases of the formula NR 1 OH, wherein R 1 is C 1 -C 5 alkyl or tetraarylammonium bases of the formula NA 1. OH wherein A is a phenyl or alkylphenyl radical.

. The role of clathrates is to contribute to the desired crystal structure with pores of a defined size, and therefore they are composed of molecules of the corresponding size.

The products obtained according to the invention are characterized by protonic acidity which can be modified by varying the introduced substitution cation. For pure silica, the number of milliequivalents of hydrogen ions per gram of sample is 1.10, which acidity can be increased by the introduction of aluminum atoms up to about 1.10 milliequivalents of hydrogen ions per gram of sample.

The materials obtained by the process of the present invention are also significant in their defined crystalline structure, as will be further apparent from the attached X-rays shown in Figures 1 and 2, which have a large specific surface area in excess of 150 m / g and generally reaching 300-500. m / g.

The presence of aluminum, which so strongly modifies silica acidity, has a beneficial effect on the formation of crystalline materials whose spectra are either strongly similar to those in the literature for crystalline silica called silicalite (Nature, 271, 512 (1978)) or vice versa varies considerably.

The aluminum-modified silica obtained by the process of the present invention may be used for catalytic or adsorption purposes either as such or dispersed on a support, more or less inert, which may have a large or small specific surface area and porosity.

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

The amount of carrier material in the final product may range from 1 to 90%, preferably from 5 to 60% by weight.

Examples of suitable carriers include clays, silica, alumina, diatomaceous earth, silica-alumina mixtures, and other materials.

The aluminum-modified silica obtained by the process according to the invention can advantageously be used as a catalyst for a wide variety of reactions, for example preferably for the alkylation of benzene, in particular the alkylation of benzene with ethylene and the alkylation of benzene with ethanol.

Other possible uses include the following reactions:

- alkylation of toluene with methanol to xylene, predominantly to p-xylene,

- disproportionation of toluene to produce mainly p-xylene,

- conversion of dimethyl ether and / or methanol or other (lower) alcohols to hydrocarbons such as olefins and aromatics,

- cracking and hydrocracking,

- isomerisation of normal paraffins and naphthenes,

- polymerization of compounds containing olefinic or acetylene bonds,

- reforming,

- isomerization of polyalkyl-substituted aromatics such as o-xylene,

- disproportionation of aromatics, in particular toluene,

- conversion of aliphatic carbonyl compounds to at least partially aromatic hydrocarbons,

- separation of ethylbenzene from other _Cg aromatics, ¹

- hydrogenation and dehydrogenation of hydrocarbons,

- methanization.

In the accompanying drawings, which relate to the following examples, FIG. 1 is a X-ray diffraction pattern of the product of Example 4, and FIG. 2 is a X-ray diffraction pattern of the product of Example 6.

Hereinafter, some examples of the practice of the present invention will be given, which are intended to illustrate the process without limiting it in any way. »

He did

This example illustrates the process for preparing porous crystalline silica in which aluminum has been introduced into the crystal lattice as a replacement for silicon using the designation TRS-22.

In a glass vessel (pyrex glass), which was maintained under a constant nitrogen atmosphere, was charged 80 grams of tetraethyl orthosilicate (TEOS), which was heated to 80 ° C with stirring. 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 milliliters of distilled water was then added, stirring at 80 ° C until homogeneous and clear. mixture, which took about 1 hour.

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

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

The mixture was then made up to 150 ml with distilled water, and then the glass jar was placed in an autoclave and left at 155 ° C for 7 days. After cooling, the resulting solid was centrifuged for 15min at 10,000 rpm ^-3 min, suspended again in distilled water and again centrifuged and the wash step was repeated four times. The product was dried in a drying apparatus at 120 ° C and found to be X-ray crystalline.

Chemical analysis of the product obtained, dried at 120 ° C, revealed the following composition:

SiO ₂ ai ₂ o ₃ Na ₂ 0 99.52% by weight 0.24% by weight 0.22% by weight k ₂ o 0.02% by weight

The chemical formula of the product is: 1 Si. / 0.002 8 / AI. 0 ^. The loss on ignition of this product at 1100 ° C was 16.6%, with a SiO ₂ : Al ₂ O ₃ molar ratio of 704.

The alkali metals present in the end product were derived from the reactants and glass, since they were not separately added. In order to remove alkaline impurities, the material may 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 at 550 ° C for 6 hours. .

The specific surface area determined by the BET method was 444 m / g, with the amount of protons per gram of sample corresponding to 1.5. 10 ^-1 meq / g.

Example 2

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

In a glass vessel (pyrex glass) equipped with a reflux condenser and maintained under a nitrogen atmosphere, 40 grams of tetraethyl orthosilicate (TEOS) and 120 ml of a 20% aqueous solution of tetrapropylammonium hydroxide (mass concentration) were charged, and the mixture heated to boiling. In this way, a translucent colorless solution was obtained, which remained clear after a long reflux.

It was then added 30 mg of aluminum nitrate A1 _{(NO3> 9.3} HJO and the liquid passed to opalescent appearance, while continuing to heat at a separated white powder.

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

The product dried at 100 ° C was crystalline X-ray. The product was calcined at 550 ° C for 16 hours in a stream of air and was then repeatedly washed with boiling water. distilled water containing dissolved ammonium acetate, after which the solid was calcined again at 550 ° C for 6 hours.

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

SiO _n

99.78% by weight 0.20% by weight 0.02% by weight

The general formula for this product is: 1 Si. / 0.002 4 / AI. O _y .

The annealing loss at 1100 ° C was 3.58% by weight, with a SiO ₂ : Al ₂ O ₃ molar ratio of 816.

The trace amounts of alkali metals present in this product were derived from reaction components and glass, as these were not added separately. The specific surface area, determined by BET, was 420 m / g, with a proton concentration per gram of sample of 1.9. 10 ^-1 meq / g.

Example 3

This example illustrates a process for preparing porous crystalline silica designated TRS-23, in which aluminum has been introduced into the crystal lattice as a replacement for silicon using an organic basic compound other than in Examples 1 and 2, namely tetraethylammonium hydroxide.

In this procedure, the same manner as in Example 1 and reacting said 80 grams of tetraethyl orthosilicate, 68 ml of an aqueous solution of tetraethylammonium hydroxide at 25 and weight 80 mg of aluminum nitrate A1 _{(NO3> 9.3} H ₂ O, dissolved in 50 ml absolute ethanol, and 2 grams of sodium hydroxide pellets, which were dissolved in 10 mL of distilled water, leaving the mixture at 155 ° C for 18 days.

The product thus obtained was X-ray crystalline after drying at 120 ° C. The concentration of protons per gram of sample (calcined at 550 ° C for 4 hours) was 1.1. 10 & meq / g.

Chemical analysis of a carefully washed sample, which was calcined at 550 ° C for 4 hours, revealed the following composition:

SiO ₂ 99.77% by weight

AljOj 0.20% by weight

Na ₂ O · 0.03% by weight

The general formula of the product is: 1 Si. / 0.002 4 / AI. O.

The loss on ignition at 1,100 ° C was 3.47% by weight, the molar ratio being ύ of this product: SiO ₂ : Al ₂ O ₃ = 816. The BET specific surface area was 470 m ² / g and the proton concentration per gram of sample was 4.3. -30 ^-3 meq / g.

Example 4

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 tetrabutylammonium hydroxide as the organic base.

In this example, the same procedure was carried out as in Example 1, wherein 50 grams of tetraethyl orthosilicate (TEOS), a solution of 100 milligrams of aluminum nitrate and ( ₃ ) ₃ , were reacted. 9 H ₂ O in 50 milliliters of absolute ethanol, a solution of 29 grams of tetrabutylammonium bromide 257251 hydroxide (obtained from tetrabutylammonium bromide and moistened silver oxide) in 120 milliliters of distilled water, and 2 grams of sodium hydroxide dissolved in 20 milliliters of distilled water.

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

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

The concentration of protons per gram of sample (calcined at 550 ° C for 5 hours) was

-d

4,5. 10 meq / g.

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

SiO ₂ 99.66% by weight

AOg 0.31% by weight

At ₂ 0 0.03% by weight

The general product pattern is: 1 Si. (0.003 6). AI. The loss on ignition at 1100 ° C for this product was 3.67% by weight, the molar 2 SiO ₂ : Al ₂ O 3 ratio was 543, the specific BET surface area was 380 m / g and the protolyte concentration per gram of sample was 2, 5. 10 ³ meq / g.

1 is a diffraction X-ray diffraction pattern of the products obtained by the process of this example.

Example 5

In this example, a process for preparing a porous crystalline silica designated TRS-20, in which aluminum as a yardstick for silicon has been introduced into the crystal lattice, will be illustrated in the absence of an inorganic alkaline base compound, i.e., a silica. that the only possibility of the presence of alkali cations is from the trace impurities present in the reactants used.

The procedure was as in Example 1, wherein 40 grams of tetraethyl orthosilicate, a solution of 100 milligrams of aluminum nitrate A1 (NO ₃ ) ₃ , was reacted. 9 H ₂ O in 50 ml of absolute ethanol, 50 ml of a 40% by weight aqueous solution of tetrapropylammonium hydroxide (obtained from tetrapropylammonium bromide and moistened silver oxide) to give a product free of alkaline inorganic bases and the mixture is left at 155 ° C.

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

When used as a catalyst, the product was calcined for 16 hours in air at 550 ° C and then washed repeatedly with boiling distilled water containing dissolved ammonium acetate, whereupon the solid was annealed again at 550 ° C for 6 hours.

The product thus obtained was analyzed for its chemical composition, which was as follows:

SiO ₂ 99.68% by weight

Al2 O3 0.31% by weight

Na ₂ O 0.01% by weight

The general formula of the product is: 1 si. / 0.003 6 / -1. O ^.

The ignition loss at 1,100 ° C was 3.59% by weight, the SiO ₂ : Al ₂ O ₃ molar ratio was 544. The BET specific surface area was 500 m ² / g and the concentration of H ⁺ cations per gram of sample was 4 , 7. 10 ^-1 meq / g.

Example 6

In this example, a process for preparing a porous crystalline silica of the designation TRS-57 is illustrated, into whose crystal lattice aluminum has been introduced as a replacement for silicon using triethanolamine.

In this example, the procedure as in Example 1, was added to the reaction given 80 g of tetraethylorthosilicate, 80 mg of aluminum nitrate A1 _{(NO3> 9.3} H ₂ O, dissolved in 50 mL of absolute ethanol and a solution of 27 g! triethanolamine in 50 ml of distilled water, 7 grams of sodium hydroxide was added, the glass (pyrex glass) was placed in an autoclave and left at 194 ° C for 7 days.

The product thus obtained, dried at 120 ° C, was X-ray crystalline. The X-ray diffraction pattern of this product is shown in the attached Figure 2.

Chemical analysis of the product thus obtained, which had been calcined at 550 ° C for 4 hours, revealed the following composition:

SiO ₂ 99.74% by weight

0.2% by weight

Na ₂ O 0.05% by weight

The general formula of the product is: 1 Si. / 0.002 4 / AI. Oy.

/

The ignition loss at 1100 ° C was 3.55% by weight, the molar 2 SiO ₂ : Al ₂ O ₃ ratio was 816, the specific BET surface area was 344 m / g and the concentration of H ⁺ cations per gram of sample was 1. , 5,. 10 ^- ^ meq / g.

In the following examples, the practical possibilities of using the aluminum modified silica obtained by the process of the present invention for various reactions will be illustrated.

Example 7

First, the non-applicability of sodium cation-modified silica, which is therefore not within the scope of the present invention, for dehydration purposes will be illustrated in this first example regarding the use of the materials obtained by the process of the invention. In this example, a modified silica designated TRS-22 (see Example 1), but modified with sodium cations, was used as the catalyst, so that the proton concentration for this product -4 was only 4.1. 10 meq / g sample.

As an example of a dehydration reaction, the preparation of dimethyl ether from methanol was chosen. 4 milliliters (i.e., 2 grams) of a catalyst fraction having a particle size ranging from 600 to 180 µm was introduced into an electrically heated tubular reactor having an internal diameter of 8 millimeters. The sample exiting the reactor was analyzed by gas chromatography.

The catalyst was first calcined in a stream of nitrogen at 500 ° C for 2 hours to remove absorbed water. Methanol was then fed at a space velocity of 1.5 h at a reactor temperature of 275 ° C and then at a reactor temperature of 400 ° C.

Analysis of the reactor effluent stream confirmed only the presence of methanol at both temperatures.

Example

This example serves as a comparative example, illustrating the unusability of aluminum modified silica designated TRS-23 (see Example 3), carelessly washed so that the proton concentration was only 1.1. ^-Ti 10 meq sample, for dehydration purposes.

In the same manner as in Example 7, 4 milliliters (i.e. 2.8 grams) of catalyst having a particle size in the range of 600 to 180 µm were introduced into the reactor, and the catalyst was heated at 500 ° C for 2 hours. in a stream of anhydrous nitrogen.

Methanol was then added at temperatures of 240, 300 and 400 ° C at a mass space velocity of 1.75 h ^-1 . In all three cases, dimethyl ether was not detected in the reactor effluent stream and only methanol was detected.

Example 9

In this example, the excellent catalytic dehydration properties of the modified crystalline silica designated TRS-22 prepared according to Example 1, wherein the proton concentration was 1.5, will be illustrated. 10 ¹ meq / g of sample.

The procedure was as in Example 7, in which 5 ml (3.5 g) of a catalyst fraction having a particle size in the range of 600 to 180 µm was charged to the reactor. The catalyst was calcined in a stream of anhydrous nitrogen for 2 hours to remove absorbed water, then methanol was fed at a mass space velocity of 1.5 h ¹ and at reactor temperatures of 250 and 265 ° C.

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

It is apparent from the above results that crystalline silica prepared by the process of the invention, i. aluminum modified, has excellent dehydration efficiency, with conversion values higher than those of the active alumina process, which has been modified with silicon compounds.

As evidence, using the aluminum modified silica based catalyst of the present invention designated TRS-22, at 250 and 265 ° C and at a mass space velocity of 1.5 h ^-3 , methanol conversion equivalent to the same is achieved. , respectively. higher than the conversion achieved at a temperature of 300 ° C and a mass space velocity of 1 h ³ using active alumina modified with silicon compounds.

Table 1

Dehydration of methanol to dimethyl ether

Catalyst: TRS-22 prepared according to the procedure of Example 1

Temperature 250 ° C 265 ° C pressure (MPa) 0.1 0.1 mass space velocity (h ^-1 ) 1.5 1.5 methanol conversion (% mole) 82.4 88.1

Example 10

This example is comparative. This example will illustrate the process of converting dimethyl ether to hydrocarbons, ‘with a particular focus on light olefins, using a modified crystalline silica designated TRS-22, prepared as described in Example 1 a. -4 containing sodium cations so that the proton concentration was only 4.1. 10 meq / g of catalyst.

In an electrically heated tubular reactor having an internal diameter of 8 millimeters, 2 millimeters (i.e. 1 gram) of catalyst having a particle size ranging from 600 to 180 µm were placed. The catalyst was first heated at 550 ° C for 2 hours in a stream of nitrogen to remove any adsorbed water. Gaseous dimethyl ether was supplied through a heated line to prevent condensation. A suitable sampling heater was installed downstream of the reactor to allow the exit stream from the reactor to be fed to a gas chromatograph in which a complete analysis of the reaction products was performed.

As far as the conversion calculation is concerned, it should be noted that methanol resulting from partial hydration of dimethyl ether is considered to be an unreacted product, so that the molar conversion only applies to dimethyl ether that has been converted to hydrocarbons and carbon monoxide and carbon dioxide.

By molar selectivity of the products contemplated is meant the number of moles of dimethyl ether that have been converted to said product, based on> the total number of moles reacted.

The results obtained in carrying out this procedure are shown in Table 2 of which it is. it can be clearly seen that the test catalyst is neither too active nor too selective, as a result of the considerable carbon monoxide, carbon dioxide and methane being produced.

Table 2

Conversion of dimethyl ether to hydrocarbons

Catalyst: TRS-22 containing sodium cations

Number attempt Temperature (° C) Pressure (MPa) Spatial velocity (h ^_1 ) One pass conversion (% molar) Product selectivity CO + CO ₂ + (mole%) ₄ c ₂ h ₄ ^C 3 ^H 6 ^C 4 1 375 0.1 0.65 2,3 ' 5.0 14.9 30.1 50.0 2 475 0.1 0.20 97.0 10.9  6.5 26.1 56.5

Example 11

This example will illustrate the process of converting dimethyl ether to hydrocarbons with a particular focus on light olefins using a modified crystalline silica designated TRS-22 prepared as described in Example 1 and containing 1.5. 10 * meq. protons per gram of sample.

In this example, the same procedure was used as in Example 9, with 3 milliliters (1.5 grams) of catalyst having a particle size ranging from 600 to 180 µm were charged to the reactor. The catalyst was first heated at 550 ° C for 2 hours in a stream of nitrogen to remove adsorbed water.

The results obtained are shown in Table 3 below. Compared to Table 2, it is clear that the change in acidity improves catalyst performance.

Table 3

Conversion of dimethyl ether to hydrocarbons

Catalytic converter: TRS-22

Number attempt Temperature <° C) Pressure (MPa) Spatial velocity (h- ¹ ) One pass conversion (% mole) Selectivity to products obtained (% mole) CO + CO ₂ + ch ₄ c ₂ h ₄ ^C 3 ^H 6 ^C 4 1 305 0.1 2.7 38.8 0.5 30.1 24.3 45.1 2 335 0.1 2.7 87.9 0.5 23.0 19.9 56.6 3 365 0.1 4.7 97.3 0.5 19.0 18.8 61.7 4 365 0.1 6.7 87.4 0.5 23.2 19.7 56.6 5 485 0.1 6.7 97.1 0.5 18.3 18.7 61.9 6 485 0.1 8.7 87.1 0.5 20.1 18.2 61.2 7 440 0.1 9.0 92.1 0.5 16.5 15.2 67.8

Example 12

In this exemplary embodiment, the activity of an aluminum modified silica based catalyst designated TRS-22 (1.5 x 10 ³ meq H ⁺ / g), see Example 1, in alkylation of benzene with ethylene will be illustrated.

1.2 milliliters (0.8 grams) of a TRS-22 catalyst having a particle size in the range of 600 to 300 µm was charged to an electrically heated tubular reactor having an internal diameter of 8 millimeters. The benzene was fed by a metering pump first to a preheating system where it was contacted with a preselected amount of ethylene and then discharged to the reactor. The reaction products were analyzed by gas chromatography. The results obtained are shown in Table 4 below.

Table 4

Benzene alkylation with ethylene catalyst: TRS-22, pressure: 2 MPa, liquid phase space velocity: 14 h ³ , C ₆ H ₆ molar ratio: C ₂ H ₄ = 7

Operating time (h) Temperature (° C) Amount of ethylbenzene in the product (% mole) Amount of diethylbenzene in the product (% mole) Conversion 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 51.8 380 470 11.5 0.70 76.7 350 470 10.9 0.65 72.6 400 470 10.3 0.60 68.2

Example 13

In this example, the procedure for regenerating the catalyst used will be illustrated.

The same catalyst as Example 12 (designated TRS-22 prepared by the procedure of Example 1) was regenerated after 400 hours of operation and regenerated for 5 hours at 550 ° C in a suitably conditioned air stream. After regeneration was complete, the system was purged with nitrogen for 1 hour, also at 550 ° C, and then reacted under the conditions of Example 12.

The results obtained are shown in Table 5 below.

Table 5

Alkylation of benzene with ethylene

Catalyst: regenerated TRS-22, pressure: 2 MPa, liquid phase space velocity: 14 h ^-1,. molar ratio C ₈ H 8: C ₂ H 4 = 7

Opening hours (h) Temperature (° C) Amount of ethylbenzene in the product (% mole) Amount of diethylbenzene in the product (% mole) Conversion 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 14

In this example, the activity of an aluminum modified silica based catalyst designated TRS-0 (see Example 2) in the alkylation of benzene with ethanol will be illustrated.

1.2 milliliters (0.8 grams) of catalyst having a particle size ranging from 600 to 300 µm 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 fed through the metering pump, first to the preheater and then to the reactor.

The reaction was carried out at 440 ° C and the reaction products were analyzed by gas chromatography. The results obtained are shown in Table 6.

Table 6

Alkylation of benzene with ethanol catalyst: TRS-0, temperature: 440 ° C, pressure: 2 MPa, liquid phase space velocity: 10 h ^- \ molar ratio CgHg: C ₂ HgOH = 4

Table 6 continued

Operating time (h) Amount of ethylbenzene in the product (% mole) Amount of diethylbenzene in the product (% mole) C ₂ HgOH Conversion (%) 50 19.0 1,2 100 ALIGN! 100 ALIGN! 19.0 1,2 100 ALIGN! 150 19.0 1,2 100 ALIGN! 200 19.0 1,2. 100 ALIGN! 300 19.0 1,2 100 ALIGN! 400 19.0 1,2 100 ALIGN!

Example 15

5 milliliters of TRS-0-modified aluminum silica prepared according to Example 5 were impregnated with an aqueous solution of hexachloroplatinic acid H ₂ PtClg such that the platinum content of the catalyst was 0.2% by weight.

Platinum was reduced to an elemental mold at 600 ° C in a stream of hydrogen, which was then transferred to an electrically heated tubular reactor having an internal diameter of 20 millimeters.

The exhaust gas removal capacity of cars was tested on two typical reactions, namely the oxidation of propylene to carbon dioxide and the oxidation of carbon monoxide to carbon dioxide.

Test

The crude gases of 800 ppm propylene, 8% oxygen and the rest of the nitrogen were preheated to 120 ° C and then fed to the catalyst at a gas phase space velocity of 50,000 h. Propylene was converted to 99%. The same gas mixture, preheated to 90 ° C, was fed to the catalyst at a gas phase space velocity of 20,000 h -1, with a propylene conversion achieved of 99%.

Test B

The 2.5% carbon monoxide, 8% oxygen, and the rest of the crude gases were preheated to 80 ° C and fed to the catalyst at a gas phase space velocity of 20,000 h.

The same gas mixture preheated to the same temperature was fed to the catalyst at a gas phase space velocity of 50,000 h ^-2 , whereby the carbon monoxide conversion achieved was 99. 80 ° C to 120 ° C is in fact to be considered exceptional since the best commercially available catalysts used in catalytic mufflers achieve the same conversion of polypropylene and carbon dioxide at the same space velocities as mentioned above, but at a temperature that never does not lie below 150 ° C.

Example 16

This example illustrates the activity of an aluminum modified silica based catalyst of the invention designated TRS-57, prepared according to Example 6, in the alkylation of benzene with ethylene.

The reaction was carried out in a fixed bed tubular reactor having an internal diameter of 8 millimeters with electric heating. The reactor was charged with 1.2 milliliters (0.85 grams) of catalyst having a particle size ranging from 600 to 300 µm. Benzene was then fed through the metering pump, first to a preheating system where it was combined with a preselected amount of ethylene, and then to the reactor. The reactor effluent was analyzed by gas chromatography. Table 7 shows the results obtained.

Table 7

Benzene alkylation with ethylene catalyst: TRS-57, pressure: 2 MPa, temperature: 440 ° C, liquid phase space velocity: 14 h ^-1 , molar ratio = 7

Operating time (h) Amount of ethylbenzene in the product (% mole) Amount of diethylbenzene in the product (% mole) Conversion ethylene (%)

10 13.9 1.35 100.0 ⁵⁰ 13.9 1.35 100.0 100 ALIGN! 14.0 1,3Q 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 0.90 78.9

Example 17

In this example, the catalyst used in Example 16 for ethylene alkylation, designated TRS-57, was subjected to regeneration, which was carried out in situ with a stream of air diluted with nitrogen at 500 ° C.

After regeneration, the catalyst was reused for alkylation of benzene with ethylene. The results obtained are shown in Table 8, which shows that it is very advantageous to regenerate the catalyst.

Table 8

Alkylation of benzene with ethylene

Catalyst: regenerated TRS-57, pressure: 2 MPa, temperature: 440 ° C, liquid phase space velocity: 14 h ¹ , CgH ₆ : C ₂ H ₄ = 7 molar ratio.

Operating time (h) Amount of ethylbenzene in the product (% mole) Amount of diethylbenzene in the product (% mole) Ethylene Conversion (%) 10 14.0 1.30 100.0 50 13.9 1.35 100.0 100 ALIGN! 13.8 1.40 100.0 150 13.8 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 18

This example illustrates the activity of an aluminum modified silica based catalyst of the invention designated TRS-57, prepared as described in Example 6, in alkylating benzene with ethanol.

The reaction was carried out by placing 1.2 milliliters (0.85 grams) of a particle size catalyst in the electrically heated fixed bed tube reactor.

600 to 300 µm. The reaction mixture containing benzene and ethanol was then fed through the metering pump, first to the preheating system and then to the reactor. The output stream was analyzed by gas chromatography. The results obtained are shown in Table 9.

Table 9

Alkylation of benzene with ethanol

Catalyst: TRS-57, strand: 2 MPa, temperature: 440 ° C, liquid phase space velocity: 10 h ^_1 , CgH ₆ : C ₂ H ₅ OH = 5 molar ratio

Operating time (h) Amount of ethylbenzene in the product (% mole) Quantity of diethylbenzene in the product (% mole) C ₂ H ₃ OH 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 modified silicas obtained by the process of the present invention is their ability to be used as catalysts for the alkylation of hydrocarbons, olefins and / or paraffins to hydrocarbons having a high octane number. As mentioned above, these aluminum modified silicas 2 are porous, their specific surface area is greater than 150 m / g and their composition corresponds to the above general formula.

In the following example, this specific possibility of applying the modified silica prepared by the process of the invention will be illustrated.

Example 19

In this embodiment, a porous crystalline silica prepared according to Example 5 was used as catalyst for the alkylation of isobutane with normal butenes as the catalyst of Example 5, in which aluminum was substituted for the silicon crystal.

In a small reactor as described in Example 7, 3 milliliters of catalyst (1.9 grams) having a particle size ranging from 600 to 300 µm were charged.

The conditions used and the results are shown in Table 10 below.

Tab. 10 * Pressure: 2 MPa, molar ratio of isobutene to n-butene: 15 Temperature Spatial speed (h Alkylation based on butenes (%) Product composition 250 1.3 100 ALIGN! about 90% of the isoparaffins 20% aromatics and about 350 1.3 100 ALIGN! about 50% of isoparaffins 50% aromatics and about 350 5.0 90 about 70% of isoparaffins 30% aromatics and about

OBJECT OF THE INVENTION

Claims (8)

OBJECT OF THE INVENTION A process for producing aluminum modified silica having a porous crystalline structure having a specific surface area greater than 150 m / g of the general formula: Si. (0.001 2 to 0.005 0) Al. O _y in which y is a number in the range of 2,001 8 to 2,007 5, and with a molar ratio of SiCl 2 / Al 2 O 6 in the range of 38 to 816, characterized in that the compound is reacted in an aqueous, alcoholic or aqueous-alcoholic solution silicon selected from the group consisting of silica and tetraalkyl orthosilicates, with an aluminum compound such as aluminum nitrate or aluminum acetate in the presence of a clathrate reagent selected from the group consisting of tertiary amines, aminoalcohols, tetraalkylammonium hydroxides having 1 to 5 carbon atoms in the alkyl moiety, and triethanolamine wherein optionally one or more mineralizing agents and optionally an inorganic basic compound are added, the mixture is left to crystallize in a closed medium for 5 to 20 days at a temperature of 100 to 220 ° C, after which it is allowed to cool and after air filtration and drying at a temperature ranging from 300 to 700 ° C for a period of time 2 to 24 hours, optionally washed with boiling distilled water containing the ammonium salt and calcined again under the above conditions. 2. The process of claim 1 wherein said tetraalkyl ortho-silicate is tetraethyl ortho-silicate or tetramethyl ortho-silicate. 3. The process of claim 1, wherein said mineralizing agent is an alkali or alkaline earth metal halide or hydroxide. 4. The process of claim 3 wherein the alkali and alkaline earth metal hydroxides and halides are selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, potassium bromide, sodium bromide, sodium iodide, calcium iodide, or sodium hydroxide. calcium bromide. Process according to claim 1, characterized in that alkali and / or alkaline earth metal hydroxides and / or ammonia hydroxides are used as inorganic bases. 6. The process of claim 5, wherein the alkali and alkaline earth metal hydroxides are selected from the group consisting of sodium hydroxide, potassium hydroxide, and calcium hydroxide. 7. The method of claim 1, wherein the amount of inorganic base and / or tetraalkylammonium hydroxide or triethanolamine is less than a stoichiometric amount relative to the silica. The process according to claim 7, characterized in that the amount of inorganic base and / or tetraalkylammonium hydroxide or triethanolamine is 0.05 to 0.50 mol per mol of silica.