NL9300562A - Method of preparing a porous, synthetic, crystalline material - Google Patents

Abstract

The invention relates to a method of preparing a porous, synthetic, crystalline material on the basis of boron- modified silicon oxide, having the general formula yR2O.(1-y)C2/nO.B2O3.xSiO2 where O<IMAGE>y<IMAGE>1, 4<IMAGE>x<IMAGE>1000, R is the product formed if an organic base has been used to form the material, C represents a cation such as H+, NH+4 or a metal having a valency of n. According to the invention, a silicon compound, a boron compound and a chelating agent (chelatant) are allowed to react under hydrothermal conditions at a pH of between 9 and 14, at a temperature of between 110 and 220 degree C for a period of from 1 to 30 days. Preferably, the reaction is carried out in the presence of a mineralizing agent, consisting of a hydroxide or halide of an alkali metal or alkaline earth metal. The materials obtained have a precisely defined porous crystalline structure which is related to the zeolite structure.

Description

Short designation: Process for preparing a porous, synthetic crystalline material.

The invention relates to a process for the preparation of a porous synthetic crystalline material based on boron-modified silicon oxide and of the general formula yR20. (ly) c2 / no. B2 O3.xsiO2 where 0 <y <1,4 <x <1000, R is the product that results when an organic base is used to form the material, C represents a cation such as H +, NH% or a metal with the dignity n.

Such a method is known from Dutch patent application 77.11239 and comprises that the oxides of boron, sodium or another alkali metal and silicon, and a tetraalkyl ammonium compound are mixed in an aqueous medium, and at a temperature of about 90 to 250 ° C react late for several hours to several weeks.

A process has now been found for preparing boron-modified silicon oxides of the above formula, which differs from this known process in that a silicon compound, a boron compound and a chelating agent are used under hydrothermal conditions at a pH between 9 and 14 at a temperature between 110 and 220 ° C for 1 to 30 days.

The boron compounds according to the invention indicated above are hereinafter referred to as "boralites" for the sake of brevity. These materials have an improved stability at a higher SiO2 to B2o3 ratio.

Furthermore, these materials have a precisely defined porous crystalline structure related to the zeolite structure.

The process for the preparation of the boralites starts from a hydrothermal reaction of a silicon compound, a boron compound and a suitable chelating agent, preferably an alkylonium compound, at a pH of 9 to 14 and at a temperature between 100 and 220 ° C for 1 up to 30 days.

High purity boralites can be prepared from organic boron and silicon compounds, for example trialkyl borates and tetraalkyl orthosilicates, the hydrothermal process being carried out in Teflon vessels (RTM) or in polypropylene, platinum or the like vessels to ensure that the alkaline solution no impurities from the crystallization vessel.

The absence of impurities gives the boralites special properties, including hydrophobic and thus a lack of dehydrating capacity.

If very high purity is not required, cheaper components can be used, for example instead of boron: boric acid, sodium borate or borax, and instead of silicon: colloidal silicon oxide, silica gel, sodium silicate, aerosil, etc. and for the crystallization vessels of glass , stainless steel or the like.

In this case, the boralites contain impurities from the constituents or from the crystallization vessel. For example, commercially available silicon oxides contain up to 2000 ppm Al2 O3 and it has been found that amounts up to 10,000 ppm Al2 O3 do not affect structural and crystallographic properties, although naturally other properties are affected, for example hydrophobic character and dehydrating capacity.

As the chelating agent, one can use compounds having an amine, ketone, alcohol or acid function as well as other functions, preferably using alkyl ammonium bases, for example tetraalkylammonium hydroxide. The choice of such compounds and of the reaction components has a decisive influence on the boralites formed.

A mineralizing agent may also be added, for example, alkali metal or alkaline earth metal hydroxide or halide.

It is pointed out here that R20 disappears partly but never completely when the boralite in question is calcined.

In particular, four different types have been prepared from the boralites of the general formula indicated above, which will be designated boralite A, boralite B, boralite C and boralite D with their own crystal structure, of which the X-ray diffraction spectra of the H + forms calcination at high temperatures (150-750 eC) show the characteristic lines indicated in Tables A to D.

The presence of other cations in place of H + causes small changes in the spectrum, similar to those of the known zeolites.

The infrared spectrum (IR) shows a characteristic band which depends on the amount of boron present and which is between 910 and 925 cm -1.

Boralite A can be characterized by the molar ratio of the anhydrous oxides as follows: yR2o. (1-y) c2 / no. b2o3. xsio2, wherein R represents a tetramethylammonium (TMA) cation, C: H +, NH + 4 or a metal ion of the n value and 8 <x <30.

The material formed by calcination of boralite A shows in the H + form, in the main lines, the X-ray diffraction spectrum of Table A.

Boralite B can be characterized by the molar ratio of the anhydrous oxides as follows: yR20. (1-y) C 2 / nO.B 203.xSiO 2, wherein R represents a tetraethylammonium cation (TEA), C: H +, NH + 4, or a metal ion of the valency n, and 5 <x <50.

The material formed by calcination of boralite B shows the X-ray diffraction spectrum of Table B in the main lines in the H + form.

Boralite C can be characterized by the molar ratio of the anhydrous oxides as follows: yR20. (1-y) C 2 / nO .B 2 O 3 .xSiO 2, wherein R represents a tetraethylammonium or tetrapropylammonium cation or a nitrogen-containing amine cation, for example ethylene amine, C: H +, NH + 4 or a metal cation of the value n, and 4 <x < 1000.

The boron-modified silicon oxide of Example V is boralite C. The material formed by calcining boralite C shows, in the main lines, the H + form the X-ray diffraction spectrum of Table C.

Boralite D can be characterized by the molar ratio of the anhydrous oxides as follows: yR20. (1-y) C2 / n0. B203. xSiO2, where R represents a tetrabutyl ammonium cation, C: H +, NH + 4 or a metal ion of the n value, and 4 <x <20.

The material formed by calcination of boralite D shows in the H + form, in the main lines, the X-ray diffraction spectrum of Table D.

Boralites are very stable at high temperatures with or without water vapor.

The boralites, in particular the aforementioned A, B, C and D boralites, can be used alone or dispersed on a more or less inert support, preferably silicon oxide, alumina or clay-like materials, for catalytic reactions or absorption processes and are used in a large number, including the above-mentioned reactions.

The invention is now further illustrated by the following examples.

EXAMPLE I

This example describes the preparation of boralite A.

A container of Pyrex glass under a co2-free atmosphere is filled with 132 g of a 25% solution of tetramethylammonium hydroxide in water and 18.6 g of boric acid are added with stirring.

After everything has dissolved, 187.5 g of tetraethyl orthosilicate are still added with stirring.

The reaction mixture is heated to 60 DEG C. with stirring, slowly producing a white milky precipitate, and the ethanol formed by hydrolysis of ethyl silicate is simultaneously filtered off.

After 12 hours, all alcohol is gone and 0.18 g KOH and distilled water are added to a total volume of about 300 ml. The reaction mixture is then placed in a Teflon-coated static autoclave and the 12-day hydrothermal treatment is started at 145 ° C. The formed product is allowed to cool to room temperature, collected on a filter, carefully washed with distilled water and dried at 120 ° C.

The product consists of crystals with a diameter of about 0.1 - 0.5 microns.

Part of the sample is calcined at 750 ° C.

The molar ratio of SiO2 -B2 of the product is 11. The X-ray diffraction spectrum of the H + form corresponds to the data in Table A.

The IR spectrum shows a typical band for boron at 921 cm1 that does not exist in normal zeolites. EXAMPLE II

This example describes the preparation of boralite A from colloidal silicon oxide.

According to the procedure and in the order of Example I, a Pyrex glass container is filled with 210 g of a 25 wt.% Solution of tetramethylammonium hydroxide, 27 g of H3B03 and 240 g of Ludox colloidal silicon oxide (concentration 40%).

After stirring and heating at 80 ° C for 1 hour, place the reaction mixture in a 1 liter titanium autoclave equipped with a stirrer and subject to the 10 day hydrothermal treatment at 150 ° C under the self-generated pressure.

The crystalline reaction product is collected on a filter, washed and dried and fired at 750 ° C for 6 hours. It shows in the H + form the X-ray diffraction spectrum shown in Table A and an IR band at 917 cm1.

This product still has the following properties:

Actual density (helium method): 2.19 g / cm3,

Acidity (CsCl method): pH 2.4

S1O2 * B2O3 ~ 12.3 EXAMPLE III

This example describes the preparation of B-type porous synthetic crystalline boralite.

Under the conditions of Example II, 110 g of a 25 wt% solution of tetraethylammonium hydroxide, 12 g of boric acid and 100 g of 40% A.S. react colloidal silicon oxide.

The hydrothermal treatment takes 9 hours at 150 ° C in a 300 ml Teflon-coated static autoclave.

The crystalline product formed, which arises after filtration, washing, drying and burning, consists of spherical particles with an average diameter of 1.3 microns.

The chemical analysis provides a molar ratio of SiO2 to B2o3 of 6.86. The X-ray spectrum in the H + form after calcination at 550 ° C corresponds to the data in Table B. The IR spectrum shows a characteristic band at 921 cm -1.

The specific surface area, which is determined with nitrogen according to the BET method, is 421 m2 / g.

The pore volume is 0.18 cm3 / g / the actual density (helium method) 2.32 g / cm3. The acidity according to the CsCl method is equal to a pH of 1.8.

EXAMPLE IV

This example describes the preparation of boralite C. Following the procedure of Example I, 90 g of 25 wt% tetrapropylammonium hydroxide, 37.5 g of boric acid, 125 ml of distilled water and 62.4 g of tetraethyl orthosilicate are reacted.

After autoclaving of Example III at 160 ° C for 11 days and the usual treatment to obtain the H + form, a product with olive particles with dimensions of 10-15 microns, an X-ray diffraction spectrum corresponding to the data of Table C and an IR band at 920 cm -1, while the molar ratio of SiO 2 to B 2 O 3 is 4.

EXAMPLE V

According to the procedure of Example IV, 37.5 g of orthoboric acid, 250 ml of water, 3 g of KOH, 180 g of a 25% by weight solution of tetrapropylammonium hydroxide, 5 g of KBr and 124.8 g of tetraethyl orthosilicate are reacted successively.

After autoclaving Example 2 for 6 days at 175 ° C and after the usual treatment to obtain the H + form, a spherical product with an X-ray diffraction spectrum corresponding to that of boralite C as indicated in Table C, an IR band is formed at 915 cm -1 and a molar ratio of SiO 2 to B 2 O 3 of 11.2.

Actual density (helium method): 2.36 g / cm3

Specific surface area (BET method with nitrogen): 377 m2 / g.

Pore volume: 0.18 cm3 / g. Pore diameter from 5 to 30 X units.

EXAMPLE VI

Following the procedure of Example IV, 30 g of tetramethyl orthosilicate, 14.6 g of triethyl borate, 1100 g of water, 80 g of tetrapropylammonium hydroxide (25% by weight) and 2 g of KOH are reacted successively and crystallized at 190 ° C for 6 days, followed by washing and according to example IV.

The X-ray diffraction spectrum of the H + form after calcination at 550 ° C corresponds to that of boralite C from Table C. The molar ratio of SiO 2 to B 2 O 3 is 17 and the surface area according to the BET method is 380 m2 / g.

EXAMPLE VII

This example describes the preparation of boralite C. Following the procedure of Example IV, 130 g of tetraethyl orthosilicate, 15 g of boric acid, 250 ml of water, 70 g of tetrapentylammonium hydroxide, are reacted successively in 250 ml of water and 5 g of KOH in 50 ml of water.

The mixture is stirred for 24 hours at 60 to 80 ° C and the mixture is stored for 12 days at 165 ° C in a 1 liter titanium autoclave equipped with a stirrer. The product calcined at 550 ° C has the X-ray diffraction spectrum of boralite C as indicated in Table C.

SiO 2 to B 2 O 3 molar ratio = 13.9.

EXAMPLE VIII

This example describes the preparation of boralite c. 88.7 g of tetraethylammonium hydroxide (20 wt.% Solution), 4.15 g of H3BO3 and 62.5 g of tetraethyl orthosilicate are reacted according to the procedure of Example IV. From the clear solution thus obtained, ethanol is evaporated at 60 to 80 ° C without a gel forming. The mixture is stored for 10 days at 150 ° C in a 250 ml stainless steel autoclave.

Under these conditions a dense gel forms which is suspended in 100 ml distilled water and to which 2.5 g KOH is added. The mixture is heated to 80 ° C with stirring and water is evaporated until a total volume of 250 ml is obtained. The operation is optionally repeated until the gel has turned milky.

The gel is left in an autoclave at 175 ° C for 15 days after which it is further treated as described in Example IV.

The X-ray diffraction spectrum in the H + form, after calcination at 550 ° C, shows the value indicated in Table C for boralite c.

The ratio of SiO 2 to B 2 O 3 is 12.1.

EXAMPLE IX

This example describes the preparation of boralite C from ethylenediamine.

According to the procedure of Example II, 4.25 g of NaOH, 120 ml of water, 6 g of H3BO3, 85 g of ethylenediamine and 50 g of 40% Ludox A.S. react colloidal silicon oxide.

The hydrothermal treatment is carried out in a 300 ml Teflon-coated autoclave at 175 ° C for 9 days.

The X-ray diffraction spectrum of the H + form calcined at 550 ° C is consistent with the data in Table C for boralite C.

The molar ratio of SiO 2 to B 2 O 3 is 11.3. EXAMPLE X

This example describes the preparation of boralite D. Following the procedure of Example I, 225 g of a 40 wt.% F solution of tetrabutyl ammonium hydroxide, 20 g of boric acid, 200 g of tetraethyl orthosilicate and 0.2 g of KOH are reacted and charged after evaporation of ethanol to 1 liter with distilled water.

The hydrothermal treatment is carried out at 165 ° C for 12 days in a titanium autoclave equipped with a stirrer.

The crystalline product calcined at 550 ° C has in the H + form the X-ray diffraction spectrum of boralite D, as indicated in Table D. The IR spectrum shows a boron-characteristic band at 919 cm -1. The specific surface area (BET / method with nitrogen) is 415 m2 / g, while the pore volume is 0.18 cm3 / g.

The molar ratio of SiO 2 to B 2 O 3 is 4.8. EXAMPLE XI

Following the procedure of Example X, 113 g of a 40 wt% solution of tetrabutyl ammonium hydroxide, 10 g of boric acid and 75 g of 40% Ludox A.S. colloidal silicon oxide react with each other.

The hydrothermal treatment is carried out in a Teflon coated autoclave at 150 ° C for 12 days.

The crystalline product thus obtained has a molar ratio of SiO 2 to B 2 O 3 of 10.4, while the H + form calcined at 550 ° C shows the X-ray diffraction spectrum of Table D. The IR spectrum shows a typical band at 918 cm -1.

The specific surface area (BET method with nitrogen) is 335 m2 / g and the pore volume is 0.155 cm3 / g.

EXAMPLE XII

An electrically heated tubular reactor with an internal diameter of 8 mm is filled with 3 ml of the catalyst boralite A, prepared according to the method of example I, with a grain size of 14 to 30 mesh (ASTM, USA series).

The reactor is filled with hot methyl tert-butyl ether via a heated tube and a metering pump.

Downstream of the reactor is a valve set at 6 bar which is connected to a heated sample-drawing device with which reactor effluent can be fed to a gas chromatograph after a pressure drop.

At the temperatures shown in Table E, methyl tert.-butyl ether is fed in an amount of 6 cc per hour, i.e. at an LHSV (spatial speed) of 2. The results are summarized in Table E.

EXAMPLE XIII

The reactor of Example XII is charged with 3 ml of the

Boralite B catalyst prepared according to Example III with a grain size of 30 to 50 mesh (ASTM, USA series). The results summarized in Table F are obtained at a pressure of 6 bar and according to the procedure of Example XII. EXAMPLE XIV

The reactor of Example XII is charged with 2 ml of the boralite C catalyst prepared according to example IV with a grain size of 7 to 14 mesh (ASTM, USA series). Methyl tert.-butyl ether is charged according to the procedure of Example XII and the test is continued for a few hours to determine whether the operation of the catalyst remains constant.

The process is carried out in an oven at 150 ° C, a pressure of 6 bar and an LHSV of 2. The results are summarized in Table G.

EXAMPLE XV

The reactor of Example XII is charged with 3 ml (1.35 g) boralite D, prepared according to the procedure of Example X, with a grain size of 30 to 50 mesh (ASTM, USA series).

Methyl tert-butyl ether is added under the conditions indicated in Table H. The results are summarized in Table H.

TABLE A

BORALITE TYPE A

Mesh plane distances Relative intensity d (A)

8.82 M

8.25 S

6.52 M

6.12 M

5.61 MW

5.32 W

4.42 MW

4.27 MW

4.09 MW

4.02 MW

3.92 MW

Continued Table A

3.83 Μ

3.47 W.

3.42 W.

3.27 MW

2.88 W.

2.74 W.

2.47 W Meaning: VS = very strong MW = medium S = strong W = weak

When the molar ratio SiO 2 to B 2 O 3, the calcination temperature and the cation in question change, the above values change slightly,

TABLE B

BORALITE TYPE B

Mesh plane distances Relative intensity d (A)

11.23 S

6.52 W.

5.98 W.

4.08 MW

3.90 S

3.46 MW

3.26 MW

3.05 W.

2.98 MW

2.65 W.

2.05 W Meaning: vs = very strong MW = medium S = strong w = weak

When the molar ratio SiO 2 to B 2 O 3, the calcination temperature and the cation in question change, the above values change slightly.

TABLE C

BORALITE TYPE C

Mesh plane distances Relative intensity d (A)

11.09 US

9.94 S

9.67 MW

6.66 W

6.33 MW

5.96 MW

5.67 MW

5.55 MW

5.33 W

5.00 W.

4.95 W.

4.58 W

4.34 W

4.24 MW

3.98 W.

3.83 S

3.80 S

3.73 MW

3.70 M

3.63 MW

3.46 W.

3.42 W.

3.33 W.

3.29 W.

3.23 W.

3.03 MW

2.97 MW

2.93 W.

2.72 W.

Continued Table C

2.59 W

2.48 W.

2.41 W.

2.38 W.

2.00 MW

1.98 MW Meaning: VS = very strong MW = medium S = strong W = weak

When the molar ratio SiO2 to B2O3, the calcination temperature and the cation in question change, the above values change slightly.

TABLE D

BORALITE TYPE D

Mesh plane distances Relative intensity d (A)

11.12 US

10.00 S

6.67 W

6.36 W.

5.97 M

5.56 MW

4.99 MW

4.59 W

4.34 W.

3.83 S

3.70 M

3.62 W.

3.46 W.

3.33 W.

3.04 W.

2.97 MW

2.50 W.

2.48 W.

Continued Table D

2.00 MW

Meaning: VS = very strong MW = medium S = strong W = weak

When the molar ratio SiO 2 to B 2 O 3, the calcination temperature and the relevant cation are changed, the above values change slightly.

Claims (10)

1. Process for preparing a porous synthetic crystalline material based on boron-modified silicon oxide and of the general formula yR20. (1-y) C2 / a0. B2O3 »xSiO2 where 0 <y <1, 4 <x <1000, R is the product that results when an organic base is used to form the material, C represents a cation such as H +, NH + 4 or a metal with the value n, characterized in that a silicon compound, a boron compound and a chelating agent are reacted under hydrothermal conditions at a pH between 9 and 14 at a temperature between 110 and 220 ° C for 1 to 30 days. A method according to claim 1, characterized in that the silicon compound is an organic silicon compound. Process according to claim 2, characterized in that the organic silicon compound is a tetraalkyl orthosilicate. Method according to claims 1-3, characterized in that the boron compound is an organic boron compound. Process according to claim 4, characterized in that the organic boron compound is trialkyl borate. 6. A method according to claims 1-5, characterized in that the chelating agent is an alkyl ammonium compound. A method according to claim 6, characterized in that the alkyl ammonium compound is a tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium or tetrapentylammonium compound. A method according to claims 1-7, characterized in that the chelating agent is a compound with an amine function. Process according to claim 8, characterized in that the chelating agent is ethylenediamine. 10. Process according to claims 1-9, characterized in that the reaction is carried out in the presence of a mineralizing agent consisting of an alkali metal or alkaline earth metal hydroxide or halide.