GB2120226A

GB2120226A - Synthetic crystalline porous material comprising silicon and boron oxides

Info

Publication number: GB2120226A
Application number: GB08311310A
Authority: GB
Inventors: Giovanni Perego; Vittorio Fattore; Marco Taramasso
Original assignee: SnamProgetti SpA
Current assignee: SnamProgetti SpA
Priority date: 1982-05-07
Filing date: 1983-04-26
Publication date: 1983-11-30
Also published as: BE896686A; NL8301590A; LU84790A1; ES8406380A1; KR840004534A; IT8221132A0; ZW9183A1; YU95483A; PL241838A1; DK195883D0; ES522608A0; PT76656B; GR78258B; SE8302576L; BR8302358A; SE8302576D0; IT1157932B; DE3316488A1; DD209795A5; DK195883A

Abstract

Synthetic crystalline porous materials of a zeolitic nature, consisting of silicon and boron oxides, are prepared by reacting, under hydrothermal conditions, a silicon derivative, a boron derivative a mixture of tetramethylammonium and tetrabutylammonium hydroxides or, as an alternative, a mixed quaternary base of (methyl-butyl) ammonium hydroxide, optionally with an alkali metal hydroxide or ammonium hydroxide being present. The materials have the empirical formula: a R2O.(1-a)Me2O.B2O3.xSiO2 wherein a is from 0 to 1, x is from 30 to 120, Me is a H<+> cation, an NH<+>4 cation or an alkali metal cation, and R is (i) a mixture of a tetramethylammonium cation and tetrabutylammonium cation, and/or (ii) a quaternary (methyl-butyl) ammonium cation.

Description

SPECIFICATION Synthetic crystalline porous materials cornpnsipgiIion and boron oxides This invention relates to synthetic materials comprising silicon and boron oxides having a porous and crystalline structure of a zeolitic nature.

Synthetic materials based on silicon and boron oxides are known. In GB-2024790-A, there are disclosed four synthetic materials which consist of silicon and boron oxides and which have a crystalline and porous structure. These materials, called Boralite A, Borålite B, Boralite C and Boralite D, are synthesized in the presence of organic substances, preferably tetraalkylammonium ions, which have the effect of leading the synthesis towards the desired structure. These ions are tetraethylammonium cations for Boralite A, tetraethylammonium cations for Boralite B, tetramethylammonium cations, tetrapropylammonium cations or cations derived from ethylenediumine for Boralite C, and tetrabutylammonium cations for Boralite D.

Quite surprisingly, we have now found a novel boralite family. which we call Boralites E, which are prepared by the use of a mixture of tetraalkylammonium bases or mixed tetraalkylammonium bases.

The ammonium bases used to obtain Boralites E are mixtures of tetramethylammonium and tetrabutylammonium hydroxides in any ratio, or mixed bases such as tributylmethylammonium hydroxide, dimethyldibutylammonium hydroxide and butyltrimethylammonium hydroxide.

The boralites of the "E" family can be represented, in their anhydrous state, in terms of the molar ratios of the their oxides, by the following formula: aR2O.(1 -a)Me2O.B2O3.xSiO2 wherein a is from 0 to 1, xis from 30 to 120, R is one or more of the quaternary ammonium cation(s) mentioned above, Me is a cation such as H+, No4 or an alkali metal ion.

The synthetic materials according ot the present invention are crystalline, according to X-ray analysis. This analysis may be carried out by means of a diffractometer of the kind suitable for powders and equipped with an electronic pulse counting device, CuKa radiation being used. For calculating the intensities, the heights of the peaks are measured and reported in terms of percentages relative to the height of the most intense peak.

The X-ray diffraction spectrum of Boralites E is similar to that of Boralites C as far as the values of the interplanar distances, d, are concerned but significant variations are experienced in the intensity ratios in comparison with Boralites C. More particularly, it is to be noted, in the spectrum of Boralites E, that the intensity of a number of reflections typicat of Boralites C is lower relative to others, which others retain their characteristic intensities. Boralite E spectrum displays a total dissappearance of such reflections.

Because of the variability in the X-ray diffraction spectrum we refer herein to a Boralite "family" rather than to a single compound.

The principal reflections involved in the phenomenon aforementioned are characterized by the following values ford: 9.65 + 0.10 6.32 + 0.07 A 5.67 + 0.07 A 4.24 + 0.005 A 3.98 t 0.05 3.73 + 0.05 3.63 t 0.05 A 3.42 + 0.05 A 2.93 + 0.05 .

To give a quantitative idea of the phenomenon, we have compared the ratio of the intensity of the reflection at d = 3.63 + 0.05 ( to that of the reflection with invariant intensity at d = 3.83 + 0 0.05 (12). In the case of Boralite C, the ratio 11:12 is, typically enough, near 0.40:1. In the case of Boralites E, this ratio is lower and can drop to values of the order of 0.1:1.

!n any individual Soralite E, the intensity decrease is similar, in terms of percentage, for all the reflections aforementioned, whereas the magnitude of the phenomenon varies from one product to another.

Table 1 is a comparison between the X-ray diffraction spectrum of a Boralite E (as obtained according to the precedure of Example 4 hereinafter) and the corresponding spectrum of a typical Boralite C (as prepared according to GB-2024790-A). Both spectra relate to products in the H+form, that is, products which have been calcined for 6 hours at 550"C, ion-exchanged with ammonium acetate and calcined once again at 550"C for 6 hours.

Minor variations in the spectrum given in Table 1 can be caused by variations of the Si:B ratio, the calcination temperature or the presence of cations.

TABLE 1 Boralite C Boralite E 26 d(A) Rel.Int. d(A) Rel. Int 8.00 11.05 100 7.99 11.06 100 8.89 9.95 47 8.87 9.97 48 9.17 9.64 16 9.15 9.66 5 9.93 8.91 1.2 9.91 8.93 0.7 12.00 7.37 1.1 11.98 7.39 0.8 12.61 7.02 0.7 12.59 7.03 0.3 13.31 6.65 3,7 13.29 6.66 3.7 14.03 6.31 9 14.00 6.32 2.5 14.89 5.95 11 14.86 5.96 11 15.65 5.66 6.6 -15.63 5.67 2 16.01 5.54 6.9 15.99 5.54 6.6 16.65 5.32 1.4 16.63 5.33 0.5 17.40 5.10 1 17.37 5.11 0.7 17.78 4.988 2.6 17.75 4.997 2.6 17.93 4.947 3.3 17.89 4.957 2.8 18.33 4.840 0.4 18.29 4.850 0.2 19.39 4.578 2.7 19.34 4.589 2.5 20.07 4.424 0.6 19,99 4.442 0.5 20.51 4.330 3.8 20.46 4.341 3.5 20.98 4.234 6.7 20.93 4.244 1.6 21.90 4.058 0.8 21.82 4.073 0.5 22.33 3.981 2.6 22.32 3.983 1.2 23.23 3.829 40 23.19 3.835 36 23.44 3.795 31 23.38 3.805 26 23.86 3.729 14 23.82 3.735 7 24.07 3.697 20 24.03 3.703 19 24.57 3.623 16 24.52 3.630 6 24.93 3.572 1.3 24.85 3.583 1.8 25.74 3.461 2.2 25.69 3.468 2.3 26.05 3.420 4.2 26.00 3.427 1.4 TABLE 1 (continued) Boralite C Boralite E 20 d(A) Rel. Int. 28 d(A) Rel. Int.

26.41 3.376 1.4 26.34 3.383 1.5 26.79 3.328 3.1 26.72 3.336 2.7 27.11 3.289 4.2 27.00 3.302 2.4 27.67 3.224 1.4 27.55 3.238 0.8 28.26 3.158 0,8 28s.17 3.168 0.7 28.63 3.118 1.2 28.56 3.125 0.5 29.47 3.031 5 29.39 3.039 4 30.14 2.965 4.5 30.06 2.973 4.2 30.57 2.924 3.1 30.50 2.931 1.1 31.42 2.847 0.9 31.36 2.852 0.7 32.35 2.767 0.5 32.26 2.775 0.4 32.97 2.717 1.9 32.90 2.722 0.4 33.62 2.666 0.4 33.54 2.672 0.1 33.94 2.641 0.4 33.86 2.647 0.3 34.61 2.592 2 34.51 2.599 1.4 34.86 2.574 0.9 34.78 2.579 0.2 35.12 2.555 0.8 35.04 2.561 0.3 35.40 2.536 0.5 35.32 2.541 0.5 35.92 2.500 1.2 35.86 2.504 0.9 36.30 2.475 1.9 36.24 2.479 1.4 37.42 2.403 1.1 37.36 2.407 0.8 37.77 2.382 1.4 37.68 2.387 0.8 43.35 2.000 3.5 45.23 2.005 3 45.79 1.982 3.6 45.65 1.987 2.4 46.79 1.941 0.8 46.67 1.946 0.3 47.77 1.904 -0.9 47.61 1.910 0.5 48.92 1.862 1 48.80 1.866 0.8 A preferred method for preparing Boralites E comprises reacting, under hydrothermal conditions, a silicon derivative, a boron derivative, a mixture of tetramethylammonium and tetrabutylammonium hydoxide at determined ratios or, as an alternative, a mixed quaternary base of methylbutylammonium hydroxide as hereinbefore defined, optionally in the presence of an alkali metal hydroxide or ammonium hydroxide, at a pH of from 9 to 13, at a temperature of from 100 to 220"C and for a time of from 2 days to 30 days.

Table 2 shows the molar ratios between the reactants.

TABLE 2 Molar Ratio Wide Range Preferred Range Ski02:8203 0.5:1 to 30:1 1:1 to 15:1 R:SiO2 0.05:1to5:1 0.1:1to0.3:1 H2O:SiO2 10:1to50:1 20:1to40:1 MeSiO2 O to 0.5:1 0.01:1 to 0.4:1 The molar ratio of the tetramethylammonium cation to the tetrabutylammonium cation, when such a mixture is used, is preferably from 0.3:1 to 3:1.

The silicon derivative is preferably selected from tetraaikylorthosilicates (such as tetraethylorthosilicate and tetramethylorthosilicate) or from colloidal silica, silica-gel, sodium silicate and Aerosil (RTM).

The boron derivatives is preferably selected from trialkylborates, tetraalkylborates, boric acid, sodium borate and borax.

The choice of the silicon and the boron derivatives depends, above all, upon the purity of the material one intends to obtain.

Boralites E can be used for catalytic purposes or for absorption uses, either as such or when disposed on a more or less inert substrate, preferably selected from silica, alumina and clay-like materials.

Such Boralites can be used, as catalysts, in many reactions, such as those illustrated in GB-2024790-A referred to above.

The following Examples illustrate the invention.

Example 1 This example illustrates the preparation of a Boralite E.

In a Pyrex (RTM) glass vessel maintained in an atmosphere deprived of CO2, there were subsequently introduced, with stirring, 400 g of distilled water, 90.6 g of tributylmethylammonium hydroxide as a 40% by weight aqueous solution, 8.3 g of boric acid and 0.26 g of sodium hydroxide. On completion of the dissolution, there were added, still with stirring, 138.69 of tetraethylorthosilicate.

The reaction mixture was maintained at 70"C for 5 hours, still with stirring, to dispel the ethanol produced by the hydrolysis of the tetraethylorthosilicate.

The milky gel thus obtained was mixed with distilled water to make the total volume up to 400 ml. The reaction mixture was transferred into an autoclave fitted with a stirring mechanism and was maintained therein at 1 600C for 60 hours under the pressure which is spontaneously generated within the autoclave by the reaction.

Upon cooling to room temperature, the resulting product was separated from its mother liquor by centrifuging, washed with running distilled water to remove any soluble impurities and finally dried at 120"C.

A portion of the product was calcined for 6 hours at 550"C, exchanged with ammonium acetate and calcined once again at 550"C for 6 hours.

The ratio SiO2: IB2O3 of the resulting material was 60:1. The Boralite E thus obtained was characterized, not only by an X-ray diffraction spectrum similar to that of Table 1, but also by a ratio Ii and 12 of 0.34:1 (wherein I1 and 12 are as explained above).

Examples 2 to 9 Other Boralites of the "E" family were prepared as in Example 1, but with the ratios between the reactants as tabulated in Table 3 below.

As the silicon source in Example 8, there was used the coilloidal silica Ludox A.S. (RTM) containing 40% by wight of silica, whereas, in the other examples, tetraethylorthosilicate was used as the silicon source.

The Me cation used was sodium, the only exceptions being Examples 8 and 9, in which ammonium was used.

The quaternary ammonium case used varies: in Example 2, there was used tributylmethylammonium hydroxide (3B1 M); in Example 3, dibutyldimethylammonium hydroxide (2B2M); and in the other Examples, a mixture, in different ratios, of tetramethylammonium hydroxide (TMA) and tetrabutylammonium hydroxide (TBA).

The boralites of the E-family thus obtained were characterized in particular by their SiO2:B203 ratio and by their 11:12 ratio.

TABLE 3 Example 2 3 4 5 6 7 8 9 RN+ 3B1M 2B2M TMA TMA TMA TMA TMA TMA =1 =3 =1/3 =1 =1 =1 TBA TBA TBA TBA TBA TBA SiO2/B2O3 10 10 10 10 10 10 10 2 R/SiO2 0.25 0.25 0.25 0.25 0.25 0.125 0.25 0.17 Me/SiO2 0.10(a) 0.01(a) 0.01(a) 0.01(a) 0.01(a) 0.01(a) 0.20(b) 0.35(b) H2O/SiO2 30 30 30 30 30 30 30 39 Crystallization 165 160 165 165 160 160 160 170 temperature ( C) Crystallization 6 6 6 6 6 9 6 15 time (days) SiO2/B2O3 110 95 57 48 44 41 60 39 I1/I2 0.30 0.35 0.18 0.18 0.13 0.16 0.19 0.17 (a) Me = Na+ (b) Me = NH+4

Claims

CLAIMS 1. A synthetic crystalline porous material of a zeolitic nature, comprising silicon and boron oxides and having, in its anhydrous state, the following empirical formula: aR20.(1 -a)Me20.B203.xSiO2 wherein a is from 0 to 1, is from 30 to 120, Me is a H+ cation, an NH4+cation or an alkali metal cation, and R is (i) a mixture of a tetramethylammonium cation and tetrabutylammonium cation, and/or (ii) a quarternary (methyl-butyl) ammonium cation.
2. A material as claimed in claim 1, prepared by reacting under hydrothermal conditions (i) a silicon derivative, (ii) a boron derivative, (iii) a mixture of tetramethylammonium hydroxide and tetrabutylammonium hydroxide or, as an alternative, a mixed quaternary (methyl-butyl)ammonium hydroxide, and, optionaily, (iv) an alkali metal hydroxide or ammonium hydroxide, the molar ratio SiO2: B203 being from 0.5:1 to 30:1, the molar ratio H20:SiO2 being from 10:1 to 50:1, the molar ratio R:SiO2 being from 0.05:1 to 5:1 and the molar ratio Me:SiO2 being from 0 to 0.5:1.
3. A material as claimed in claim 2, the SiO2:B203 molar ratio being from 1:1 to 15:1, the H2O:SiO2 molar ratio being from 20:1 to 40:1, the R:SiO2 molar ratio being from 0.1:1 to 0.3:1 and the Me:SiO2 molar ratio being from 0.01:1 to 0.4:1.
4. A material as claimed in claim 2 or 3, prepared at a temperature of from 100 to 220"C, at a pH of from 9 to 14 and at a reaction time of from 2 to 30 days.
5. A material as claimed in any of claims 2 to 4, wherein the silicon derivative is selected from tetraalkylorthosilicates, colloidal silica, silica-gel, sodium silicate and Aerosil (RTM).
6. A material as claimed in any of claims 2 to 5, wherein the boron derivative is selected from trialkylborates, tetraalkylborates, boric acid, sodium borate arld borax.
7. A material as claimed in any of claims 2 to 6, the tetramethylammonium cation :tetrabutylammonium cation ratio being from 0.2:1 to 3:1.
8. A material as claimed in any of claims 2 to 6, wherein the mixed quaternary (methyl-butyl) ammonium hydroxide is dimethyldibutylammonium hydroxide.
9. A material as claimed in any of claims 2 to 6, wherein the mixed (methyl-butyl)ammonium hydroxide is butyltrimethylammonium hydroxide.
10. A material as claimed in any of claims 2 to 6, wherein the mixed quaternary (methyl-butyl) ammonium hydroxide is tributylmethylammonium hydroxide.
1. A material as claimed jn claim 1, having an X-ray diffraction spectrum, when in the H+ form, as tabulated in Table 1 hereinabove.
12. A material as claimed in claim 1, substantially as described in any of the foregoing Examples.