WO1985001675A1

WO1985001675A1 - Procedure for producing zeolite catalysts, and alkylation process

Info

Publication number: WO1985001675A1
Application number: PCT/FI1984/000076
Authority: WO
Inventors: Peter Idelman
Original assignee: Neste Oy
Priority date: 1983-10-17
Filing date: 1984-10-16
Publication date: 1985-04-25
Also published as: AT399107B; JPS61500951A; SE453965B; CA1233459A; DK272885A; DK272885D0; DK167867B1; CH668714A5; FI76005B; GB8513696D0; IT8423170A0; DE3490487C2; SE8502661L; FI76005C; GB2169271B; IT1196297B; BE900830A; GB2169271A; FI833788A; FR2553301A1

Abstract

Procedure for producing an aluminium-boron-silicate catalyst with the configuration 0.8-1.2 M2/n 0 : Al203 : 0.005-0.1 B203 : 10150 Si02 : x H20. In the procedure, a reaction mixture is heated which contains a cation with organic nitrogen, an alkali metal oxide or a mixture of such, aluminium oxide, boron oxide and silicon dioxide and water, in a closed reaction vessel first at a higher temperature and thereafter at a lower temperature for producing an aluminium-boron-silicate catalyst. The cation containing organic nitrogen has been derived from pyrrolidine or tetraethyl, tetrapropyl or tetrabutyl ammonium chloride or their mixture.

Description

Procedure for producing zeolite catalysts, and alkylation process

The present invention concerns a procedure for producing zealite catalysts. In particular, the invention concerns Al-B-Si catalysts which are appropriate for alkylating aromatic hydrocarbons. The present invention also concerns a procedure for alkylating aromatic hydrocarbons with the aid of said catalysts.

The use of crystalline silicate compounds in alkylating aromatic hydrocarbons is known in prior art. For instance, in the U.S. Patent No 4,283,306 a crystalline silicate is described for methylating toluene to become paraxylene.

Also crystalline aluminium silicate catalysts for alkylating aromatic hydrocarbons are known in prior art. The U.S. Patent No. 2,904,697 concerns an alkylation process in which metallic aluminium silicate is used. The U.S. Patent No. 3,251,897 describes aluminium silicates of x and y type and in particular those which have as their cation either hydrogen or a rare earth metal. In several other patents, aluminium silicates are described which have a high selectivity to form parasubstituted aromatics: for instance the U.S. Patents Nos. 3,702,886, 3,965,207, 4,100,217 and 4,117,024.

In the U.S. Patent No. 4,117,024, crystalline aluminium silicates have been modified using solutions of difficultly reducible oxides such as antimony, phosphorus or boron.

Alkylation processes have been described in numerous patents. Alkylation in the vapour phase with aluminium silicate catalysts rich in silicon generally yields high conversion. The useful life of silicate catalysts is rather long, and in many instances the required pressure is low, which makes said processes economically attractive. Instances of vapour phase alkylation are, among others, the U.S. Patents No. 3,751,504 and 3,751,506.

The present invention concerns new zeolite catalysts containing silicon, aluminium and boron and in which the pores and passages are not clogged by effect of atoms, molecules or ions, for instance of sulphate or chloride ions. Hereby, the movement of reagents within the silicate is unimpeded, resulting in high degree of conversion in the alkylation process and in high selectivity.

The present invention concerns a procedure for producing such aluminium-boron-silicate catalysts which are particularly well suited to be used in alkylating aromatic hydrocarbons and which yield a high degree of conversion and/or high selectivity for producing parasubstituted hydrocarbons. The invention also concerns a procedure for alkylating aromatic hydrocarbons using said catalysts.

Thus, as taught by the invention, a procedure is introduced for producing aluminium-boron-silicate catalysts in which the SiO₂/ Al₂O₃ molar proportion is in the range 10-150, preferably in the range 10-60, and the Al₂O₃/B₂O₃ molar proportion is in the range 2-200, preferably in the range 19-200. The molecular formula of said catalysts may be expressed as follows:

0.8-1.2 M₂/n O : Al₂O₃ : 0.005-0.1 B₂O₃ : 10150 SiO₂ : x H₂O

where M is at least one cation with valence n, and x is in the range 0-60. The procedure is characterized in that a reaction mixture is heated which contains a cation with organic nitrogen, one or several alkali metal oxides, oxide of aluminium, boron and silicon and water, in a closed reaction volume at first at a temperature which is at a higher temperature, and thereafter at a lower reaction temperature during a time long enough for formation of crystalline aluminium-boron-silicate catalyst to take place.

In the above formula, M is at least one cation with valence n. M may also be a mixture of alkali metal cations, preferably of sodium and potassium cations. The organic cation containing nitrogen may be an ammonium cation, such as a tetraethyl, tetrapropyl or tetrabutyl ammonium cation. The organic cation containing nitrogen may also be a cation derived from pyrrolidine.

When producing a zeolite catalyst according to the present invention, in a reaction vessel is first heated a reaction mixture containing a cation with organic nitrogen, alkali oxide, oxide of aluminium, boron and silicon and water. Depending on the circumstances, the pressure required in the reaction varies in the range 1-15 bar. A higher starting temperature is selected in the range 175-220°C, preferably in the range 190-200°C. When higher starting temperature is used, a homogenous reaction mixture is obtained in shorter time and the forming of crystals starts sooner. The heating time at the starting temperature is preferably between 30 minutes and 6 hours. Heating is continued at lower reaction temperature in the range 100-190°C. The heating time at the lower temperature is selected preferably in the range 1-6 days.

It is possible in a catalyst according to the invention to exchange ions against other cations, applying the known ion exchange technique. A recommendable practice is to exchange an alkali metal ion for a hydrogen ion, which increases the activity of the catalyst in aromatic alkylation.

As taught by one embodiment of the invention, the catalyst produced in the manner described in the foregoing may be further modified using compounds containing boron, whereby a catalyst is produced which in alkylation produces parasubstituted aromatics at high yield. The modification may be accomplished by mixing a catalyst produced as descrdibed above and boric acid, boron oxide or their mixture in dry state. Thereafter the mixture is heated at 300-700ºC, preferably at 550-600°C, with mixing from time to time. The heating time is not critical. When a catalyst modified in this manner is used, parasubstituted aromatics are obtained with high yield in alkylation.

The catalysts of the invention may, of course, be used either as such or combined with conventional carriers and bonding agents.

The invention also concerns an alkylation process in which Al-B-Si catalysts produced by the procedure of the invention are utilized. With the process, various hydrocarbons such as benzenes, naphthalenes, anthracenes and substituted derivatives such as toluene and ethylbenzene can be alkylated.

For alkylating agent in the process of the invention numerous compounds may be used which have at least one reactive alkyl radical, such as ethylene, propylene, formaldehyde, alkyl halides and alcohols.

The process conditions in alkylation, such as the temperature, pressure and flow rate, are generally critical, depending on the starting materials, and they are described more in detail in the following.

The alkylation process of the invention is accomplished in the vapour phase. For reactor is used either a fluidized bed reactor or a stationary bed reactor. The aluminium-boron-silicate to be used as catalyst is present in the form of hydrogen. The reactor pressure may vary, depending on reactor type, catalyst quantity, catalyst particle size and other factors, from atmospheric pressure up to 10 bar. The temperature may vary in the range 200-700º C, preferably in the range 300-600ºC. Prior to contacting the input materials with the catalyst, they are heated to desired reaction temperature. The flow rate that is used depends on the reaction agents, the reactor, and it generally varies in the range 1-100 hr^-1 (WHSV). The molar proportion of aromatic hydrocarbon and alkylation agent may vary in the range 0.5-20. The molar proportion recommended in monoalkylation is 1-4. In addition, a dilution gas may be used, e.g. nitrogen and/or agents reducing the coke formation, for instance hydrogen.

The hot product flow emerging from the reactor is cooled to room temperature or to a lower temperature, whereafter the liquid and gas phases are separated. The gases that have not reacted may be stored and reused. The liquid components which have not participated in the reaction, such as toluene, are separated from the product mixture for instance by distilling and reused.

In the following examples, the producing of the catalyst of the invention is described more in detail.

Example 1

In this example, the aluminium-boron-silicate catalyst carrying the identification BOA-1 is produced.

4.05 g NaOH were dissolved in 165 ml water. To the solution,

87,85 g tetrapropylammonium bromide were added at room temperature, thereby obtaining solution A.

Solution B was prepared by dissolving 4.2 g NaA10„ (containing 28.4% by weight Na₂O, 46.8% by weight Al₂O₃, and 24.8% by weight H₂O and 0.19 g Na₂B₄O₇ x 10 H₂O (containing 16.3% by weight Na₂0, 36.5% by weight B₂O₃ and 47.2% by weight H₂O) in 405.5 g H₂O. Solutions A and B were thereafter mixed together and introduced in an autoclave, in which in addition 34.2 g SiO₂ (silicagel) and 82.8 g water were placed. The composition of the mixture was as follows: 0.02 mol Na₂O, 0.02 mol Al₂O₃, 0.001 mol B₂O₃, 0.57 mol SiO₂, 0.33 mol N(CH₃CH₂CH₂)₄ and 36.3 mol water.

The mixture was heated at 200º C for two hours, and thereafter at 160º C temperature for three days. Subsequent to cooling to room temperature, the crystalline product was filtered and washed with 2 litres of water. The crystals were dried at 100º C and thereafter calcined at 530º C for 18 hours.

The catalyst thus obtained was contacted with a 5% by weight solution of ammonium chloride at 80º C for 1.5 hours. The procedure was repeated three times, using each time 15 ml solution per one gramme of catalyst. The product was filtered and washed with water until chloride-free. Drying was carried out at 100º C, and after drying calcination was performed in air at 530º C overnight, whereby the hydrogen form of the catalyst BOA-1 was obtained. The surface area of the catalyst was 345 m²/g.

Example 2

This example concerns the synthesis of the aluminium-boron-silicate catalyst BOA-2.

The following ingredients were mixed in water (265 g) : 6.5 g NaAlO₂ (containing 28.4% by weight Na₂O, 46.8% by weight Al₂O₃ and 24.8% by weight H₂O) and 0.29 g Ma₂B₄O₇ (containing 16.3% by weight Na₂O, 36.5% by weight B₂O₃ and 47.2% by weight H₂O). To the mixture were added 2.78 g NaOH, and it was well mixed. The mixture was placed in an autoclave, and 900 g H₂O, 395 g SiO₂ and 141g pyrrolidine were added. The mixture was heated at 200º C for three hours, and thereafter at 165º C for three days, whereafter it was cooled to room temperature during 15 hours. The crystals were filtered and washed with water (3 litres). The further preparation of the catalyst BOA-1 took place as in Example 1, with the difference that at temperatures higher than 100º C a nitrogen atmosphere was used instead of air.

Example 3

In this example, modification with boric compounds of the catalysts BOA-1 and BOA-2 is carried out.

To the catalysts prepared in Examples 1 and 2 (5 g thereof) were admixed 0.5 g B₂O₃, followed by heating in air at 550°C for one hour. During the heating, the components were mixed five times. After this treatment, the modified catalysts were ready to be used.

Toluene ethylating tests were performed using the unmodified and modified catalysts BOA-1 and BOA-2 produced in Examples 1-3.

Examples 4-8

In these examples a fluidized bed dreactor was used in which 5 g of the unmodified catalyst BOA-1 of Example 1 had been introduced. In all examples, the reaction temperature was 600º C, and the input rate and the toluene/ethylene molar proportion were varied. The results are presented in Table 1 below.

Examples 14-15

In these examples, the catalyst BOA-1 (5 g) of Example 1 was used for catalyst in a stationary bed reactor. The results are presented in Table III.

Examples 19-21

5 g of the catalyst BOA-2 of Example 3 were modified as in Example 3, and in the alkylation tests a fluidized bed reactor and 600º C reaction temperature were used. The results are presented in Table V.

Example 22

Methylation of toluene was accomplished with metanol using toluene/ methanol molar proportion 2:1. The catalyst was BOA-2 of Example 2, modified as in Example 3. The reaction was carried out in a stationary bed reactor, at 500º C. The yield was 1% of pure isomer-free p-xylene.

Claims

1. Procedure for preparing an aluminium-boron-silicate catalyst with the configuration

0.8-1.2 M₂/n O : Al₂O₃ : 0.005-0.1 B₂O₃ : 10150 SiO₂ : x H₂O

characterized in that a reaction mixture is heated which comprises a cation containing organic nitrogen, an alkali metal oxide or a mixture of such, aluminium oxide, boron oxide and silicon dioxide and water, in a closed reaction vessel at first at a higher starting temperature, and thereafter at a lower reaction temperature for forming the aluminium-boron-silicate catalyst.

2. Procedure according to claim 1, characterized in that the starting temperature is at least 165°C and not higer than 220º C, and that the heating time at the starting temperature is in the range 30 minutes to 6 hours.

3. Procedure according to claim 1 or 2, characterized in that the lower reaction temperature is in the range 100-190º C, preferably in the range 130-170º C, and that the heating time at this temperature is at least 8 hours and preferably 1-6 days.

4. Procedure according to any one of claims 1-3, characterized in that the cation containing organic nitrogen has been derived from pyrrolidine or from tetraethyl, tetrapropyl or tetrabutyl ammonium chloride, or from a mixture of these.

5. Procedure according to any one of claims 1-4, characterized in that the cation containing organic nitrogen is totally or partially substituted with proton in order to form a catalyst having the form of an acid.

6. Aluminium-boron-silicate catalyst in which the SiO₂/Al₂O₃ molar proportion is in the range 10-150 and the Al₂O₃/B₂O₃ molar proportion is in the range 2-200, characterized in that the catalyst has been produced by modifying a catalyst produced according to claims 1-4 with boric acid, boron oxide or their mixture.

7. Catalyst according to claim 6, characterized in that the quantity of boron compound used in modification is 0.1-30% by weight, preferably 0.5-10% by weight.

8. Procedure for producing a catalyst according to claim 6 or 7, characterized in that a reaction mixture is heated which contains a cation with organic nitrogen, an alkali metal oxide or a mixture of such, aluminium oxide, boron oxide and silicon dioxide and water, to produce an aluminium-boron-silicate catalyst, and by modifying the catalyst thus obtained by contacting it with boric acid, boron oxide or their mixture, using no water or other solvent.

9. Procedure according to claim 8, characterized in that the modification is accomplished at 300-700°C.

10. Alkylation process for alkylating aromatic hydrocarbons, characterized in that for catalyst is used an Al-B-Si catalyst produced by a procedure according to claims 1-5 or an unmodified Al-B-Si catalyst according to claim 6 in its hydrogen modification, or a catalyst modified according to claims 8-9.

11. Alkylation process according to claim 10, characterized in that it is carried out either in a fluidized bed or a stationary bed reactor.

12. Alkylation process according to claim 10, characterized in that the hydrocarbons are benzenes, naphthalenes, anthracenes or substituted derivatives, such as toluene, xylene, ethylbenzene and phenols.

13. Alkylation process according to claim 10, characterized in that the alkylating agent contains at least one reactive alkyl radical, for instance ethylene, propylene, alcohol, formaldehyde or alkyl halide.

14. Alkylation. process according to claim 10, characterized in that the reaction temperature is in the range 200-700º C, the flow rate (WHSV) in the range 1-100 hr¹ and the reaction pressure is atmospheric pressure or higher.

15. Alkylation process according to claim 10, characterized in that an inert dilution gas is used, for instance nitrogen and/or substances reducing the formation of coke, for instance hydrogen.