CH645076A5 - MODIFIED SILICA WITH ALUMINUM. - Google Patents

Description

The present invention relates to a crystalline silica modified with aluminum. Many materials based on silica and alumina are known, some of the natural type and others synthetic. Among these materials, zeolites are particularly known for their absorbent properties, molecular sieves and catalysts.

They have a variable alumina content within wide ratios with respect to silica with a maximum silica / alumina ratio of 100/1, but preferably much lower generally around 2.

Such materials, containing aluminum in tetrahedral coordination, as a vicariant of silicon, to achieve electrical neutrality must have cations that balance the charges due to the presence of aluminum atoms in tetrahedral coordination.

The proton acidity of these zeolites is to be attributed to the ato-5 ml of hydrogen introduced by exchange of these cations.

On the other hand, crystalline silicas, not having proton charges by their very nature, cannot express any acidity other than that characteristic of silicic acid.

10 In fact, numerous types of crystalline silica from quartz to cristobalite to tridymite, keatite, etc. are known. prepared according to procedures widely described in the scientific literature.

For example Heidemann, in Beitr. Min. Petrog. 10, 242 15 (1964), by reacting an amorphous silica with 0.55% KOH at 180 ° C, in two and a half days obtains a crystalline silica, called X silica, which also has a surface area of about 10 m2 / g and has poor stability since in five days it changes to cristobalite and subsequently 20 to quartz. Recently Flanigen et al, Nature, 271, 512 (1978), have obtained a crystalline silica, silicalite, with a high surface area and, for its hydrophobic characteristics, have proposed its use for the purification of water contaminated with organic substances .

25 The object of the present invention is to modify the nature of a crystalline silica with aluminum leaving its stability unchanged, so that it can be used as a catalyst or for the preparation of catalysts.

In fact, it has surprisingly been found that it is possible to obtain materials with a very high silica / alumina ratio, which cannot be zeolite since the minimum quantities of aluminum cause a great variation in acidity.

In fact, these materials have a proton acidity equal to or greater than that of the proton forms of the 3s zeolites themselves, while maintaining the very high structural stability of a crystalline silica, contrary to what occurs for the proton forms of zeolites A, X, Y, ( with the exception of those of the mordenite family) which are somewhat labile, easily tending to become the most stable 4o aluminum silicas.

Aluminum silicas, for their part, have lower acidity: for example a commercial alumina silica containing 25% by weight of aluminia has a concentration of milliequivalents H + per gram of catalyst of the order 45 of 1 X IO-3.

It has also been surprisingly found that by appropriately dosing the quantity of aluminum in the material, it is possible to adjust its acidity so that it adapts particularly to that required by the type of reaction in which it is intended to use it.

An object of the present invention is a silica modified by introduction of aluminum atoms so as to present the most suitable acid and catalytic properties for certain reactions.

55 Another object of the present invention is a suitable procedure for the preparation of these materials.

Modified silica with the introduction of aluminum atoms responds to the following general formula:

I know 1 Yes. (0.0012 - 0.0050) Al. Or where y goes from 2.0018 to 2.0075.

Depending on the calcination temperature, greater or lesser quantities of crystallization water may be present.

To obtain the aluminum-modified silica object of the present invention, the preparation method indicated below can advantageously be used.

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A silicon derivative and an aluminum derivative are reacted in an aqueous, alcoholic or hydroalcoholic solution with a substance having an archival or clathing effect, possibly adding one or more mineralizing agents to promote crystallization and possibly an inorganic base: crystallize everything in a closed environment for a period from a few hours to several days at a temperature from 100 ° to 220 ° C, preferably at a temperature from 150 ° C to 200 ° C for a week; it is cooled and after filtration and washing it is dried and calcined in air at a temperature of between 300 and 700 ° C, preferably at 550 ° C, for a time of between 2 and 24 hours; it is then washed, to remove any exchangeable cationic impurities, with boiling distilled water containing an ammonium salt, preferably nitrate or acetate, and finally calcined further as previously described.

The silicon derivatives can be selected from a silica gel obtained in any case or from a tetralkylorthosilicate such as for example tetraethylorthosilicate and tetramethylorthosilicate.

The aluminum derivatives are preferably chosen from among the salts of aluminum such as for example nitrates, acetates.

The substances having archivolt or clathing effect can be chosen among tertiary amines, amino alcohols, amino acids, polyalcohols and quaternary ammonium bases such as for example tetraalkylammonium (NR4OH) where R is an alkyl radical with 1-5 carbon or tetraarylamonium-atom (NA4OH) ) wherein A indicates a phenyl or alkyl phenyl radical.

Archived substances have the function of creating a crystalline structure with pores of specific dimensions and therefore are made up of sufficiently large molecules.

The mineralizing agents can be selected from hydroxides and alkaline or alkaline earth halides such as for example Li OH, Na OH, KOH, Ca (OH) 2, KBr, Na Br, Na I, Ca I2, Ca Br2.

The added inorganic base can be selected from the alkaline or alkaline earth hydroxides, preferably NaOH, KOH, Ca (OH) 2 and ammonia.

As regards the quantity to be used of inorganic base and / or substance having archival or clathing effect, they are generally lower than the stoichiometric with respect to silica and preferably between 0.05 and 0.50 moles per mole of silica.

The products thus obtained are characterized by a proton-like acidity which can be controlled by varying the vicariant cation introduced; for a pure silica there is a number of milliequivalents of hydrogen ions per gram of sample of 1 X IO-3, but this acidity can be increased with the introduction of aluminum until reaching a number of milliequivalents of hydrogen ions per gram of sample of approximately 1 X 10_1.

The materials of the present invention are characterized by a well-defined crystalline structure, as can be seen from the X-ray diffraction spectra shown in figs. 1 and 2 and have a high surface area, greater than 150 m2 / g and generally between 300 and 500 m2 / g. The presence of aluminum which significantly modifies the acidity of silica gives rise to the formation of crystalline materials whose spectra can be or considerably similar to those reported in the literature for crystalline silica called sicalite (Nature, 271, 512 (1978) or significantly different.

The aluminum-modified silica according to the present invention can be used for catalytic or absorption purposes as such or dispersed in a more or less inert support, with high and low surface area and porosity.

The support has the function of improving the physical and mechanical stability and possibly the catalytic properties of the material. The procedure usable for obtaining the supported material can be chosen from those known in the art and to those skilled in the art.

s The amount of support can be between 1 and 90% but preferably between 5% and 60%.

Preferred substrates include clays, silica, alumina, diatomaceous earth, alumina silica, etc.

The aluminum modified silica according to the present invention finds useful use as a catalyst for a huge number of reactions among which we can mention benzene annihilation, particularly the alkylation of benzene with ethylene, alkylation of benzene with alcohol ethyl. Other possible uses are:

15 1) Alkylation of toluene with methanol to produce xylene, mainly para-xylene.

2) Disproportionation of toluene to mainly produce para-xylene.

3) Transformations of dimethyl ether and / or methanol or other 20 lower alcohols into hydrocarbons (olefins or aromatic).

4) Cracking and hydrocraking.

5) Isomerization of n-paraffins and naphthenes.

6) Polymerization of compounds containing olefinic or acetylenic bonds.

25 7) Reforming.

8) Isomerization of substituted polyalkyl aromatics, for example ortho xylol.

9) Disproportionation of aromatics, particularly of toluene.

30 10) Conversion of aliphatic carbonyl compounds into hydrocarbons, at least partially aromatic.

11) Separation of ethylbenzene from other aromatic C8 hydrocarbons.

12) Hydrogenation and dehydrogenation of hydrocarbons. 35 13) Methanation.

We will now provide some examples having the purpose of better illustrating the invention which however must not be understood as absolutely limited to them.

4th Example 1

This example illustrates the preparation of the TRS 22 porous crystalline silica in whose crystalline lattice aluminum has been introduced as a vicariant.

In a pyrex glass container kept constantly in a nitrogen atmosphere, 80 g of tetraethylorthosilicate (TEOS) are placed which are heated under stirring up to the temperature of 80 ° C. A solution in 80 ml of distilled water of 20 g of tetrapropyl-ammonium hydroxide (obtained from tetrapropylammonium bromide and so wet silver oxide in order to have a product free of inorganic alkaline bases) is then added and is kept under stirring always at 80 ° C until the mixture becomes homogeneous and clear (time required about 1 hour).

80 mg of Al (NOg) 3 are subsequently added. 55 9 H20 dissolved in 50 ml of absolute ethanol.

A compact gel is formed almost instantaneously to which distilled water is added up to a total volume of 200 ml, stirring is intensified if necessary and the mixture is brought to the boil in order to complete the hydrolysis and eliminate all the ethanol (i.e. both added and released by hydrolysis).

The time required for this operation is 2-3 hours; the gel slowly turns into a white powder, precursor of the modified crystalline silica.

65 The preparation is brought back to the volume of 150 ml with distilled water and the pyrex glass container is then introduced into the autoclave and kept at a temperature of 155 ° C for 7 days. After cooling the solid formed is centrifuged

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at a speed of 10,000 revolutions per minute for 15 minutes, the cake is redispersed in distilled water and centrifuged again; this washing operation is repeated four times. It is dried in an oven at 120 ° C and it is found that the product thus obtained is crystalline under X-rays.

Chemical analysis on the sample dried at 120 ° C furnaces the composition:

Si02 weight%

83.0

Weight% A1203

0.2

% weight Na ^

0.18

Weight% K20

0.02

Loss by calcination a

1100 ° C

16.6%

The Si02 / AI203 molar ratio is equal to 704.

The alkaline metals present come from reagents and glass, as they have not been deliberately added.

To completely eliminate pre-alkaline impurities. If the mixture is present, it can be calcined for 16 hours at 550 ° C in an air stream and subsequently washed repeatedly with boiling distilled water containing dissolved ammonium acetate and calcined again at 550 ° C for 6 hours.

The surface area determined by the BET method is 444 m2 / g.

The concentration of proton milliequivalents per gram of sample is equal to 1.5 X 10_1.

Example 2

This example illustrates the preparation of the TRS 0 porous crystalline silica in whose crystalline network traces of aluminum have been introduced as vicariates.

40 g of tetraethylorthosilicate (TEOS) and 120 ml of an aqueous solution of tetrapropylammonium hydroxide at 20% by weight and heated to boiling are placed in a pyrex glass balloon, equipped with a reflux refrigerant and maintained in a nitrogen atmosphere.

The final result is a clear and colorless solution that remains so even after prolonged boiling to drop.

At this point 30 mg of A1 (N03) 3 are added. 9 H20 and an opalescence of the liquid occurs from which, prolonging the heating, a white powder separates.

It is kept in constant boiling for a period of 6 days, it is cooled, filtered, washed with distilled water and dried at 100 ° C.

The product dried at 100 ° C is crystalline on X-rays. It is calcined for 16 hours at 550 ° C in an air stream and then washed repeatedly with boiling distilled water containing dissolved ammonium acetate and is calcined again at 550 ° C for 6 hours.

The chemical analysis on the sample thus obtained provides the composition:

Weight% Si02 96.2

Weight% A1203 0.2

Weight% NajO + K20 0.02 Calcination loss a

1100 ° C 3.58%

The Si02 / Al203 molar ratio is equal to 816.

The traces of alkaline metals present come from reagents and glass as they have not been deliberately added.

The surface area determined by the BET method is 420 m2 / g.

The concentration of proton milliequivalents per gram of sample is equal to 1.9 X IO-1.

Example 3

This example illustrates the preparation of a porous crystalline silica, called TRS 23, in whose crystalline lattice aluminum was introduced as vicariant and in whose preparation my different organic base, tetraethylammonium hydroxide, was used, compared to that used in examples 1 and 2.

The procedure is carried out as in example 1 by reacting 80 g of tetraethylorthosilicate, 68 ml of aqueous solution at 25% by weight of tetraethylammonium hydroxide, 80 mg of A1 (N03) 3. 9H20 dissolved in 50 ml of absolute ethanol and 2 g of NaOH in drops dissolved in 10 ml of distilled water, and is maintained at the temperature of 155 ° C for 18 days.

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

The concentration of proton milliequivalents per gram of calcined sample at 550 ° C is 1.1 X IO-6.

The chemical analysis on the sample thoroughly washed and calcined at 550 ° C provides the composition:

Weight% Si02 96.3

Weight% A1203 0.2

Weight% Na ^ 0.03

Loss by calcination a

1100 ° C 3.47%

The Si02 / Al203 molar ratio is equal to 816.

The surface area determined by the BET method is 470 m2 / g.

The concentration of proton milliequivalents per gram of sample is equal to 4.3 X IO-3.

Example 4

This example illustrates the preparation of a porous crystalline silica, called TRS 19, in whose crystalline lattice aluminum was introduced as a vicariant and in whose preparation a different organic base, tetrabutylammonium hydroxide, was used, compared to those used in previous examples. The procedure is carried out as in example 1 by reacting 50 g of tetraethylorthosilicate (TEOS), a solution of 100 mg of A1 (N03) 3. 9H20 in 50 ml of absolute ethanol, a solution of 29 g of tetrabutylammonium hydroxide (obtained from tetrabutylammonium bromide and wet silver oxide) in 120 ml of distilled water and 2 g of NaOH dissolved in 20 ml of distilled water.

It is placed in an autoclave at a temperature of 155 ° C for 16 days.

The product dried at 120 ° C is crystalline on X-rays. The concentration of proton milliequivalents per gram of sample calcined at 550 ° C is 4.5 X IO-4.

Chemical analysis on the thoroughly washed sample provides the composition:

Weight% Si02 96.0

Weight% A1203 0.3

Weight% NajO 0.03

Loss by calcination a

1100 ° C 3.67%

The Si02 / Al203 molar ratio is equal to 543.

The surface area determined by the BET method is 380 m2 / g.

The concentration of milliequivalents H + per gram of sample is equal to 2.5 X 10-1.

Fig. 1 represents the X-ray diffraction spectrum.

Example 5

This example illustrates the preparation of a porous crystalline silica, called TRS 20, in whose crystalline lattice aluminum was introduced as vicariant and whose preparation was carried out in the absence of inor5 alkaline bases.

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ganic (the only alkaline cations can result from the traces of impurities present in the reagents used).

Operating as in the example - 40 g of tetraethylorthosilicate, a solution of 100 mg of Al (NOs) 3 are reacted. 9H20 in 50 ml of absolute ethanol, 50 ml of a 40% by weight aqueous solution of tetrapropylammonium hydroxide (obtained from tetrapropylammonium bromide and wet silver oxide, in order to have a product free of inorganic alkaline bases) and is maintained at 155 ° C for 10 days.

X-ray shows the crystallinity of the sample dried at 120 ° C.

For catalytic use, the product is calcined at 550 ° C in air for sixteen hours and washed repeatedly with boiling distilled water containing dissolved ammonium acetate and finally calcined again at 550 ° C for 6 hours.

The product obtained results from chemical analysis of the following composition:

Weight% Si02 96.1

Weight% Al2Os 0.3

Weight% Naj. 0.01

Loss by calcination at 1100 ° C 3.59%

The Si02 / Al203 molar ratio is equal to 544.

The surface area determined by the BET method is 500 m2 / g.

The concentration of H + ions per gram of sample is equal to 4.7 X 10_1 milliequivalents.

Example 6

This example illustrates the preparation of the TRS 57 porous crystalline silica in whose crystalline lattice aluminum was introduced as vicariant and in whose preparation triethylnolamine was used.

80 g of tetraethylorthosilicate, 80 mg of A1 (N03) 3 are reacted. 9H20 dissolved in 50 ml of absolute ethanol, a solution of 27 g triethanolamine in 50 ml of distilled water, operating as in example 1.

7 g of sodium hydrate are added and the pyrex glass container is introduced into the autoclave and kept at a temperature of 194 ° C for 7 days.

The product dried at 120 ° C is found to be crystal clear on X-rays.

The X-ray diffraction spectrum is shown in. Fig. 2. Chemical analysis on the calcined sample at 550 ° C provides the compositions:

Weight% Si02 96.2

Weight% A1203 0.2

Weight% Na ^ 0.05

Loss by calcination a

1100 ° C 3.55%

The Si02 / Al203 molar ratio is equal to 816.

The surface area determined by the BET method is 344 m2 / g and the concentration of milliequivalents H + per gram of sample is equal to 1.5 X 10_1.

Example 7 (comparative)

This example illustrates the lack of dehydrating catalytic properties of the modified crystalline silica TRS 22 prepared according to example 1 and containing sodium cations so that the concentration of proton milliequivalents per gram of catalyst is 4.1 X IO-4.

As an example dehydration reaction, the formation of dimethyl ether from methanol was chosen.

In a tubular reactor with an internal diameter of 8 mm, electrically heated, 4 ml (= 2 g) of catalyst are introduced in the fraction between 30 and 80 mesh of the ASTM USA series.

Downstream of the reactor, a sampler of the reaction effluent is placed and analyzed by gas-chromatography.

The catalyst is initially calcined at 500 ° C for two hours in anhydrous nitrogen stream to eliminate the adsorbed water.

Methanol is then fed with a space velocity (WHSV) of 1.5 g / g X h, with an oven temperature of 275 and subsequently 400 ° C.

The analysis of the reaction effluent shows the presence of only methanol at both temperatures.

Example 8 (comparative)

This example illustrates the lack of dehydrating properties of the modified crystalline silica TRS 23 prepared according to example 3 and not thoroughly washed so that the concentration of proton milliequivalents per gram of catalyst is 1.1 X 10 -6.

Working with the methods and equipment described in Example 7, 4 ml (= 2.8 g) of catalyst in the particle size between 30 and 80 mesh of the USA ASTM series are introduced into the reactor and heated for two hours at 500 ° C in anhydrous nitrogen stream.

Methanol is then fed at temperatures of 240-300 and 400 ° C with a spatial velocity (WHSV) of 1.75 g / g X h. In all three cases the presence of dimethyl ether is not verified in the reaction effluent, and only the methanol fed is found.

Example 9

This example illustrates the excellent de-degrading catalytic properties of the modified crystalline silica TRS 22 prepared according to example 1 and having a concentration of proton milliequivalents per gram equal to 1.5 X 10_1. Operating with the methods and equipment described in Example 7, 5 ml (= 3.5 g) of catalyst are introduced into the reactor in the fraction between 30 and 80 mesh of the ASTM USA series.

After calcining for 2 hours in anhydrous nitrogen stream to eliminate the adsorbed water, methanol is fed with a WHSV space velocity of 1.5 g / g X h at the reactor temperatures of 250 and 265 ° C.

The analysis of the reaction effluent consisting of dimethyl ether, unreacted methanol and water, without noting the presence of by-products in quantities detectable by gas chromatography, provides the results shown in table 1.

It can be seen that the crystalline silica object of the present invention has an excellent dehydrating activity, with conversions higher than those described in the Swiss patent application n. 15007/75 of 19.11.1975 by the same applicant for active aluminas treated with silicon compounds.

It is sufficient to observe that by operating with TRS 22 at 250 ° and 265 ° C, with a WHSV = 1.5 of the methanol conversions approximately equal and higher than those obtained at 300 ° C and WHSV = 1 respectively on active alumina treated with compounds of the silicon.

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In a tubular reactor with an internal diameter of 8 mm, electrically heated, 2 ml (- 1 g) of catalyst are introduced in the grain size between 30 and 80 mesh of the USA ASTM series.

5 The catalyst is heated beforehand at 550 ° C for 2 hours in a nitrogen stream to eliminate the adsorbed water. Sx feeds dimethyl ether in the gas phase, keeping all the lines heated, to avoid the formation of condensation. Downstream of the reactor a suitably heated sample system is arranged, which allows the introduction of the reactor effluent into a gas chromatograph where the complete analysis of the reaction products is carried out.

As regards the calculation of the conversion, it should be noted that the methanol which is formed by partial hydration of the dimethyl ether is considered unreacted product, so the molar conversion refers to the dimethyl ether transformed into hydrocarbons and oxide and carbon dioxide.

The molar selectivities in the products refer to the number of moles of dimethylether converted into the indicated product, 20 with respect to the total number of moles reacted.

The results obtained are reported in table 2, from which it is clear that the catalyst under examination is not very active and not very selective, forming considerable quantities of carbon monoxide and carbon dioxide and methane.

TABLE 2

Conversion of dimethyl ether to hydrocarbons

TRS 22 catalyst

Try n.

Temperature ° C

Pressure bar

Space speed

WHSV

Conversion by% molar passage

Selectivity in products% molar CO + co2 + c2h4 CsHe + CH4

C4 +

1

375

1

0.65

2.3

5.0

14.9

30.1

50.0

2

475

1

0.20

97.0

10.9

6.5

26.1

56.5

40 Example 11

This example illustrates the conversion of the dimethyl ether to hydrocarbons, with particular regard to the light olefins on the modified crystalline silica TRS 22 prepared according to example 1 and having a concentration of 1.5 X 10 -1 45 proton milliequivalents per gram of sample.

Operating with the methods and equipment described in Example 9, 3 ml (= 1.5 g) of catalyst are introduced into the reactor in the grain size between 30 and 80 mesh of the USA ASTM series.

so The catalyst is heated beforehand for 2 hours at 550 ° C in a nitrogen stream to eliminate the adsorbed water.

The results obtained are reported in Table 3. From the comparison with Table 2 it is clear how the behavior of the catalyst has clearly improved with the variation of the acidity.

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TABLE 1 De-hydration of methanol with dimethyl ether Catalyst: TRS 22

Temperature ° C

250

265

Pressure bar

1

1

Space speed

WHSV (g / g X h)

1.5

1.5

CH3OH% molar conversion

82.4

88.1

Example 10 (comparative)

This example illustrates the conversion of dimethyl ether to hydrocarbons, with particular regard to light olefins, on the modified crystalline silica TRS 22 prepared according to example 1 and containing sodium cations so that the concentration of proton milliequivalents per gram of catalyst is 4.1 X 10- 4.

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TABLE 3 Conversion of hydrocarbon dimethyl ether Catalyst TRS 22

Try n.

Tempe

Pressure

Space

Conversion

Selectivity in% molar products

rature ° C

speed bar

per passage

CO CO2 -ì-

C2H4

C3H6

C4 +

WHSV

molar%

+ ch4

1

305

1

2.7

38.8

0.5

30.1

24.3

45.1

2

335

1

2.7

87.9

0.5

23.0

19.9

56.6

3

365

1

4.7

97.3

0.5

19.0

18.8

61.7

4

365

1

6.7

87.4

0.5

23.2

19.7

56.6

5

485

1

6.7

97.1

0.5

18.3

00

T ™ H

61.9

6

485

1

8.7

87.1

0.5

20.1

18.2

61.2

7

440

1

9.0

92.1

0.5

16.5

15.2

67.8

Example 12

This example illustrates the activity, in the alkylation reaction of benzene with ethylene, of the catalyst TRS 22 (1.5 X 10 "1 meq H + / g).

In a tubular reactor, with an internal diameter of 8 mm, and electrically heated, 1.2 cc (0.8 g) of catalyst TRS 22 are introduced, having a particle size between 30 and 50 mesh. Through a metering pump, benzene is introduced first into a preheating system (where it meets with a predetermined flow of ethylene) and then into the reactor.

The reaction products are analyzed by gas chromatography.

Table 4 shows the data relating to the tests carried out,

TABLE 4

Alkylation of benzene with ethylene

Catalyst: TRS 22 Pressure: 20 kg / cm2 Liquid space velocity (LHSV): 14 Molar ratio C6H6 / C2H4: 7

Example 13

This example serves to illustrate the regeneration of the 25 catalysts in question.

In particular, the catalyst of the previous example (TRS 22) after 400 working hours, was regenerated at 550 ° C, in a suitably regulated air flow, for 5 hours.

At the end of the regeneration, the system is flushed with nitrogen for 1 hour, always at 550 ° C, then the reaction is started, under the same conditions as previously reported.

Table 5 shows the elative data for the tests carried out.

TABLE 5

35

Alkylation of benzene with ethylene

Catalyst: TRS 22 REGENERATED Pressure: 20 kg / cm2 Liquid space velocity (LHSV): 14 40 Molar ratio C6H6 / C2H4: 7

Work hours

Temperature ° C

Ethylben-zene molar% in products

Diethylben-zene molar% in products

% ethylene conversion

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440

13.8

1.50

100.0

50

440

13.7

1.55

100.0

100

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

Work hours

45

Temperature ° C

Ethylben-zene molar% in products

Diethylben-zene molar% in products

% ethylene conversion

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440

13.7

1.55

100.0

50

440

13.6

1.40

97.6

50100

440

13.8

1.50

100.0

150

440

13.9

1.45

100.0

200

440

13.7

1.55

100.0

55 250

440

12.2

0.95

83.9

300

440

10.3

0.60

68,45

350

440

9.8

0.38

62.85

60

Example 14

This example illustrates the activity, in the alkylation reaction of benzene with ethyl alcohol, of the TRS 0 catalyst.

65 In a tubular reactor, with an internal diameter of 8 mm, and electrically heated, 1.2 cc (0.8 g) of catalyst are introduced, having a particle size of between 30 and 50 mesh. Through a metering pump, the

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reaction mixture, consisting of benzene and ethyl alcohol, in. molar ratio 5: 1, first in a preheating system, and then in the reactor.

The reaction is carried out at 440 ° C; the reaction products are analyzed by gas chromatography.

Table 6 shows the data relating to the tests carried out.

TABLE 6

Alkylation of benzene with ethyl alcohol

Catalyst: TRS 0 Temperature: 440 ° C Pressure: 20 kg / cm2 Liquid space velocity (LHSV): 10 Molar ratio C6H6 / C2H6OH: 4

Work hours

Molar% ethylbenzene in products

Diethylbenzene molar% in products

% conversion c2h5oh

50

19.0

1.2

100

100

19.0

1.2

100

150

19.0

1.2

Ó O

You

200

19.0

1.2

100

300

19.0

1.2

100

400

19.0

1.2

100

Example 15

5 ml of the TRS 20 aluminum-modified crystalline silica prepared as shown in Example 5 are impregnated with an aqueous solution of H2 Pt Cl6 so that the platinum content in the catalyst is 0.2% by weight.

The platinum in the metallic state is reduced to 600 ° C in a hydrogen stream and introduced into an electrically heated tubular reactor with an internal diameter of 20 mm.

The abatement capacity of the exhaust gas of a car is verified with two typical reactions, namely the oxidation of propylene to carbon dioxide and the oxidation of carbon monoxide to carbon dioxide.

A) The feed gases consisting of 800 ppm of propylene, 8% of oxygen and the rest of nitrogen are preheated to a temperature of 120 ° C and fed onto the catalyst with a GHSV of 50 000 h-1.

99% of the propylene is converted.

The same gaseous mixture preheated to 90 ° C is fed onto the catalyst with a GHSV of 20 000 h-1 obtaining a conversion of propylene of 99%.

B) The feed gases consisting of 2.5% CO, 8% oxygen and the rest of nitrogen are preheated to 80 ° C and fed on the catalyst with a GHSV of 20 000 h-1, obtaining a conversion of the CO of the 59%.

The same gaseous mixture preheated to the same temperature is fed to the catalyst with a GHSV of 50 000 h ~ \, obtaining a CO conversion of 99%. The above temperatures (80-120 ° C) must be considered exceptional because the best traditional catalysts used in catalytic converters operate the same conversions as propylene and carbon monoxide at the same speed spaces at temperatures not lower than 150 ° C.

Example 16

This example illustrates the activity, in the alkylation reaction of benzene with ethylene, of the TRS 57 catalyst prepared as described in Example 6.

The reaction is carried out in a tubular, fixed bed reactor with an internal diameter of 8 mm and electrically heated.

1.2 cc (0.85 g) of the catalyst with a particle size ranging from 30 to 50 mesh are introduced.

Through a metering pump, benzene is introduced first into a preheating system (where it meets with a pre-established flow of ethylene), and then into the reactor. The effluents from the reactor are analyzed by gas chromatography.

Table 7 shows the data relating to the tests carried out.

TABLE 7

Alkylation of benzene with ethylene

Catalyst: TRS 57 Pressure: 20 kg / cm2 Temperature: 440 ° C Liquid space velocity (LHSV): 14 Molar ratio C6H6 / C2H4: 7

Work hours

Molar% ethylbenzene in products

Diethylbenzene molar% in products

% ethylene conversion

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13.9

1.35

100.0

50

13.9

1.35

100.0

100

14.0

1.30

100.0

150

13.8

1.30

98.8

200

13.9

1.35

100.0

250

13.7

1.28

97.9

300

12.5

1.02

87.6

350

11.3

0.90

78.9

Example 17

The same TRS 57 catalyst used for the alkylation reaction of benzene with ethylene described in the previous example, was subjected in situ to regeneration in an air flow diluted with nitrogen, at 500 ° C.

At the end of the regeneration, the catalyst was subjected again to the alkylation reaction of benzene with ethylene. The data shown in table 8 clearly denote the simplicity and the possibility of regeneration of the catalyst.

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645076

TABLE 8

Alkylation of benzene with ethylene

Catalyst: TRS 57 regenerated Pressure: 20 kg / cm2 Temperature: 440 ° C Liquid space velocity (LHSV): 14 Molar ratio QHg / QH ^ 7

Work hours

Molar% ethylbenzene in products

Diethylbenzene molar% in products

% ethylene conversion

10

14.0

1.30

100.0

50

13.9

1.35

100.0

100

13.8

1.40

100.0

150

13.9

1.35

100.0

200

13.8

1.40

100.0

250

13.2

1.19

93.8

300

12.8

0.95

88.5

A particular application aspect of the modified silicas according to the present invention is the use of such aluminum-modified silicas as catalysts for the alkylation of hydrocarbons having four carbon atoms, fine ole-5 and / or paraffins, to convert them into hydrocarbons having high octane rating.

As already mentioned, these modified silicas are porous and have a surface area greater than 150 m2 / g and correspond to the general formula already reported above.

II The following example 19 illustrates this particular application of the present invention.

Example 19

To alkylate the isobutane with normal butenes, a porous crystalline silica of the type obtained in Example 5 was used as catalyst, and in whose crystalline lattice aluminum was introduced as a vicariant of the silicon.

A small reactor such as that of Example 7 was loaded with 3 cm3 of catalyst (= 1.9 g) having a grain size of 30 mesh to 50 mesh.

The reaction conditions and the results obtained are reported in table 10 below.

TABLE 10

25 Pressure: 20 kg / cm2

Molar ratio of isobutane to norbutenes: 15

Example 18

This example illustrates the activity of the TRS 57 catalyst described in Example 6 for the alkylation reaction of benzene with ethyl alcohol.

The reaction is carried out by introducing 1.2 cc (0.85 g) of the catalyst, with a particle size ranging from 30 to 50 mesh, into a tubular, electrically heated fixed bed reactor. 35

With a metering pump the reaction mixture is introduced, consisting of benzene, ethyl alcohol, first in a preheating system, and then in the reactor.

The effluents are analyzed by gas chromatography.

Table 9 shows the data relating to the tests carried out.

Temp. ° C

LHSV h "1

% alkylation Composition of compared to norbutene products

250

350

350

1.3

1.3

5.0

100

100

90

about 80% isoparaffins + about 20% aromatic about 50% isoparaffins + about 20% aromatic about 70% isoparaffins + about 30% aromatic

TABLE 9

Alkylation of benzene with ethyl alcohol

Catalyst: TRS 57 Pressure: 20 kg / cm2 Temperature: 440 ° C Liquid space velocity (LHSV): 10 Molar ratio C6H6 / C2H5OH: 5

Work hours

Molar% ethylbenzene in products

Diethylbenzeng molar% in products'

% conversion of c2h5oh

50

18.8

1.3

100

100

19.0

1.2

100

150

18.8

1.3

100

200

19.0

1.2

100

250

19.0

1.2

100

300

19.0

1.2

100

400

19.0

1.2

100

45 A further practical application of the present invention is the preparation and use of a zeolite type catalyst of the class ZSM-5.

It is known from a Mobil patent, US 3 702 886, that zeolites of the class ZSM-5 can be prepared by exploiting 50 silicon derivatives, such as silica-sol, amorphous silicos such as aerosol, tetraalkyl orthosilicates or aluminum derivatives such as sodium aluminate, aluminum sulphate, aluminum acetate together with a quaternary ammonium base such as tetrapropylammonium hydroxide.

55 According to a particular embodiment of the present invention, it has been ascertained that zeolites of the ZSM-5 type can be prepared by exploiting the general teaching of the present invention whenever the material that controls the crystallization is an amino alcohol and appropriate 60 quantities of compounds are used of silicon, germanium, aluminum and gallium so that the molar ratios Si02: Al203, Ge02: Al203, SlO ^ Ga ^ and GeO ^ Ga ^ are between 5 and 100 and are preferably close to 35.

The zeolite prepared according to the present invention pre-65 feels the X-ray spectrum of the zeolite ZSM 5 responds to the general formula:

0.9 ± 0.2 M2 / nO: Y2Q3: 5-100 Y02: z H20

645 076

10

where M is a cation chosen from H + and / or NH4 + and / or metal cations and / or cations derived from amino alcohols, particularly ethanolamines, n is the valence of this cation, W is chosen in the group and h consists of aluminum and gallium, Y it is selected from the group consisting of silicon or germanium, and Z is between 0 and 40.

The preferred form of this zeolite W as aluminum, Y as silicon with a silica / alumina ratio between 10 and 60.

The preparation of the preferred zeolite according to the present invention is made by mixing the reactants within following ratios expressed in terms of moles of oxides.

Reports Interval Preferred wide interval

0H- / Si02

0.2

-0.8

0.3-

0.6

T.E.T.A./(T.E.T.A. + Na +)

0.3

-0.8

0,4-

-0.6

h2o / oh-

10

-100

20-

■ 40

where for T.E.T.A. we mean the amino alcohol in particular triethanolamine.

The process according to the present invention provides the following:

A derivative of the silicon or germanium and an derivative of the aluminum or gallium are reacted in an aqueous, alcoholic or hydroalcoholic solution with an amino alcohol e.g. ethanolamines and in particular triethanolamine, possibly adding one or more mineralizing agents such as alkaline or alkaline earth hydroxides and / or halogens to favor crystallization. The whole is crystallized in a closed environment for a period of a few hours to several days at a high temperature of 150 to 250 ° C and preferably from 170 ° C to 210 ° C for a time of 2 to 10 days, generally for a week, it is cooled and after filtration and washing with deionized water it is dried and calcined in air at a temperature of between 300 and 700 ° C, preferably at 550 ° C, for a time of 2 to 24 hours; a repeated cation exchange is then carried out with an ammonium salt preferably nitrate or acetate, washed with distilled water and finally calcined again, as previously described, if it is desired to possibly obtain the product in the H + form.

The zeolite thus prepared can be used as it is, or diluted in an appropriate ratio and added with one or more elements promoting catalytic activity according to the methods and provisions of the ZSM-5 type zeolites.

The uses of this zeolite are those foreseen for the ZSM-5.

Below are examples 20 to 22 with the aim of better illustrating the particular aspect of the invention which relates to the preparation of zeolites.

Example 20

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

In a Pyrex glass container kept in a C02-free atmosphere, gr. 60 of A1 (N03) 3. 9HaO dissolved in 400 cm3 of 95% ethyl alcohol, then are added under stirring gr. 600 of tetraethylorthosilicate. A clear solution is added gr. 200 of triethanolamine dissolved in 400 cm3 of distilled water and heated, always under stirring, to 60 ° C. After another 30 minutes, a solution of 13 g is added. of NaOH in 200 cm3 of distilled water; after another 30 minutes add another 22 gr. of NaOH (in total 35 gr. of NaOH) dissolved in 400 cm3 of water. A massive gel formation is observed; vigorous stirring is applied which is maintained for a few hours, while gradually raising the temperature to 90 ° C in order to eliminate all the ethyl alcohol introduced and that released by hydrolysis. At this point the reaction mixture is transported in a stainless steel autoclave with a capacity of three liters and the hydrothermal treatment is started at 195 ° C, which is maintained for 9 days.

The obtained product is then cooled to room temperature, filtered, washed many times with very hot distilled water and dried at 120 ° C.

It is then calcined at 550 ° C for 16 hours and is placed in H + form by repeated hot exchanges (95 ° C) with ammonium acetate (c nitrate), and new calcination at 550 ° C for 6 hours.

The X-ray spectrum corresponds to that reported in Table I of U.S. Pat. 3 702 886.

Example 21

With the modalities of the previous example, gr. 880 of tetramethylorthosilicate, gr. 120 of A1 (N03) 3. 9H20, gr. 400 of triethanolamine previously dissolved in 800 cm3 of water, 70 g of NaOH in 700 cm3 of water and carried by adding distilled water under vigorous stirring to a volume of about 9 liters. It is concentrated at the temperature of 80 ° C for about 30 hours until it has a total volume of 5 liters; the hydrothermal treatment is carried out for 8 days at 190 ° C in a stainless steel autoclave equipped with a stirrer.

The X-ray spectrum corresponds to that of the ZSM 5 and the surface area is 380 m? / G.

The SiO-j / A ^ Og ratio is equal to 38.

Example 22

9.6 gr. of sodium aluminate and 10 gr. of potassium hydroxide dissolve in 200 cc. of water. 208 g are added to the clear solution. of treitanolamine, dissolved in 1000 cc. of water. The obtained solution is left under stirring, in an inert gas flow, for two hours at 60 ° C.

Then 40 g are added as an agent which favors crystallization. of potassium bromide, dissolved in 150 cc. of water.

345 gr are slowly added. of colloidal Ludox silica (40% Si02) dissolved in 1500 cc. of water.

The obtained gel is left to age for 24 hours, at 90 ° C always in a nitrogen flow.

It then crystallizes in stainless steel autoclaves for 10 days at 198 ° C.

The treatment illustrated in Example 20 is continued, obtaining the ZSM-5 zeolite.

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1 sheet of drawings

Claims (10)

645 076 1 Yes. (0.0012 - 0.0050) Al. Oy where y goes from 2.0018 to 2.0075. 1. Silica modified with aluminum characterized by the fact that it has a porous crystalline structure and a surface area greater than 150 m2 / g and responds to the general formula: 2. Process for preparing aluminum-modified silica according to claim 1, characterized in that a silicon derivative, selected from a silica gel and a tetraalkylorthosilicate, and an aluminum derivative react in an aqueous, alcoholic and hydroalcoholic solution , chosen between a nitrate and an aluminum acetate, with a substance having an archival or clathing effect, to crystallize everything in a closed environment for a period of several hours to several days at a temperature from 100 ° to 220 ° C, to make cool everything and, after filtering and drying, calcining in air at a temperature between 300 ° and 700 ° C, for a time of 2 to 24 hours, washing with boiling distilled water and finally calcining further under the same conditions as above . 2 3. Process according to claim 2, wherein the tetral-chylortosilicate is the tetraethylorthosilicate or the tetramethylorthosilicate. 4. Process according to claim 2, wherein the substance having archival or clathing effect is selected from tertiary amines, amino alcohols, amino acids, polyalcohols and quaternary ammonium bases. 5. Process according to claim 4, wherein the quaternary amine bases are selected from tetralkylammonium (NR4OH) where R is an alkyl radical with 1-5 carbon atoms and tetrarylammonium (NA4OH) where A indicates a phenyl or alkylphenyl radical. 6. Process according to claim 2 wherein a mineralizing agent selected from LiOH, NaOH, KOH, Ca (OH) 2, KBr, NaBr, NaI, Cal2 and CaBr2 is added. 7. Process according to claim 2 wherein an inorganic base selected from NaOH, KOH and Ca (OH) 2 is added Process according to claims 6, 7, wherein the quantities of inorganic base and / or substance having archival or clathing effect are lower stoichiometric helium compared to silica. 9. Process according to claim 8, wherein the quantity of inorganic base and / or substance having archival or clathing effect are between 0.05 and 0.50 moles per mole of silica. 10. Use of porous crystalline silica as defined in claim 1, to alkylate hydrocarbons having four carbon atoms, olefins and / or saturated hydrocarbons for the purpose of preparing high octane hydrocarbons.