GB2158056A - Zeolites - Google Patents

Abstract

A new zeolite material designated Nu-32 has a molar composition expressed by the formula: 1.0 +/- 0.3M2/nO : Y2O3 : 15 to 70 XO2 : 5 to 25 H2O wherein M is at least one cation of valency n, X is silicon and/or germanium, Y is one or more of aluminum, iron, chromium, vanadium, molybdenum, arsenic, antimony, manganese, gallium or boron and H2O is water of hydration additional to water notionally present when M is H, and having an X-ray powder diffraction pattern substantially as set out in Table 1. The zeolite material is prepared from an aqueous reaction mixture containing XO2 (preferably silica),Y2O3 (preferably alumina) and a 4,4'bipyridyl compound, preferably 4,4'bipyridyl itself.

Description

SPECIFICATION Zeolites The present invention relates to a novel zeolite material, hereinafter referred to as Nu-32, and to a method for its preparation.

Aluminosilicate zeolites are now widely used in industry. Some occur only in nature, others are only available as a result of chemical synthesis and some are available in both natural and synthetic forms.

Synthetic zeolites are attracting more and more attention and it is becoming more and more possible to control the preparation of such zeolites so as to tailor their properties to particular needs.

According to the present invention a crystalline zeolite material, Nu-32, has a composition (in terms of mole ratios of oxides) expressed by the formula: 1.0 + 0.3 M2jnO: Y203: 15 to 70 XO2: 5 to 25 H2O wherein M is at least one cation of valency n, Xis silicon and/or germanium, Y is one or more of aluminium, iron, chromium, vanadium, molybdenum, arsenic, antimony, manganese, gallium or boron and H2O is water of hydration additional to water notionally present when M is H, and having an X-ray powder diffraction pattern substantially as set out in Table 1 (as determined by standard technique using copper Ka radiation) TABLE 1 26 d(A) I/lo 13.48 6.56 W 19.09 4.64 W 21.81 4.07 W 23.25 3.82 W 26.01 3.42 VS 28.07 3.18 W < M 32.19 2.78 W - M 48.87 1.86 W Note: In the table, the relative intensities are expressed as W = weak (rel into to 30), M = medium (30 to 50) S = strong (50 to 70) and VS = very strong (70 to 100).

This definition includes both freshly prepared Nu-32 ("freshly prepared" means the product of synthesis and washing, with optional drying, as hereinafter described) and also forms of the zeolite resulting from dehydration and/or calcination and/or ion exchange. In freshly prepared Nu-32, R may include an alkali metal cation and/or ammonium and hydrogen and may include nitrogen-containing organic compounds as described below. These organic components are hereinafter referred to, for convenience only, as Q.

As Nu-32 is a zeolite, the organic component(s) must be held within the zeolite framework. This nitrogen-containing organic material does not constitute part of the composition for the purposes of definition. Thus, a zeolite Nu-32 as made typically has the molar composition: 0.6to 1.1 M2O: 0.3to3.0Q : Y203: 15to70XO2: 2to25H20 where M is an alkali metal, ammonium or hydrogen.

In calcined forms of zeolite Nu-32, R may be any cation including hydrogen since the organic component is either burnt out in the presence of air, leaving hydrogen as the other balancing cation, or it is removed prior to calcination for example by dissolution in water or in organic solvent. The zeolite is readily converted to the hydrogen form by ion exchange with hydrogen ions and/or with ammonium ions followed by calcination.

Zeolite NU-32 may be prepared by reacting an aqueous mixture containing sources of at least one oxide XO2, at least one oxide Y203 and a 4,4'- bipyridyl compound, the reaction mixture having the molar composition: XO 2N203 in the range 25 to 70, preferably 30 to 60 OH-/X02 in the range 0.05 to 0.2 preferably 0.07 to 0.10 H2O/XO2 in the range 20 to 60, preferably 20 to 45 O/XO2 in the range 0.05 to 0.3, preferably 0.08 to 0.15 Z-/XO2 in the range 0 to 0.5, preferably 0 to 0.32 wherein 0 represents the 4,4'- bipyridyl compound, X and Y have the meanings as hereinbefore defined, and Z represents an acid radical.

If desired, the bipyridyl compound may be partially or fully alkylated, for example methylated. Preferably the bipyridyl compound is 4,4'bipyridyl itself.

The Applicants believe that it may be possible to synthesise zeolite Nu-32 without the use of alkali metals in the reaction mixture. If used, however, suitable alkali metals include sodium, potassium, lithium, rubidium and caesium and of these it is preferred to use sodium or potassium.

The preferred oxide XO2 is silica (SiO2) and the preferred oxide Y203 is alumina (awl203).

The silica source can be any of those commonly considered for use in synthesising zeolites, for example powdered solid silica, silicic acid, colloidal silica or dissolved silica. Among the powdered silicas usable are precipitated silicas, especially those made by precipitation from an alkali metal silicate solution, such as the type known as "KS 300" made by AKZO, and similar products, aerosil silicas, fume silicas such as "CAB-O-SIL" M5 and silica gels suitable in grades for use in reinforcing pigments for rubber or silicone rubber. Colloidal silicas of various particle sizes may be used, for example 10 to 15 or 40 to 50 microns, as sold under the Registered Trade Marks "LUDOX", "NALCOAG" and "SYTON".The usable dissolved silicas include commercially available waterglass silicates containing 0.5 to 6.0, especially 2.0 to 4.0, mols of SiO2 per mol of alkali metal oxide, "active" alkali metal silicates as defined in UK Patent 1,193,254, and silicates made by dissolving silica in alkali metal hydroxide or quaternary ammonium hydroxide or a mixture thereof.

The alumina source is most conveniently a soluble aluminate, but aluminium, an aluminium salt, for example the chloride, nitrate, or sulphate, an aluminium alkoxide or alumina itself, which should preferably be in a hydrated or hydratable form such as colloidal alumina, pseudoboehmite, boehmite, gamma alumina orthe alpha or beta trihydrate can also be used.

The reaction mixture is conveniently reacted under autogeneous pressure, optionally with added gas, for example nitrogen, at a temperature in the range 160 to 200 C, more suitably 170 to 180"C, until crystals of zeolite Nu-32 form, which can be from 1 hour to many months depending on the reactant compositions and the operating temperature. Agitation is optional, but is preferable since it assists homogenisation of the reaction mixture and reduces the reaction time. Seeding of the reaction mixture with Nu-32 crystals can also be advantageous if Nu-32 crystals dispersed in their mother liquor are used.

At the end of the reaction, the solid phase is collected on a filter and washed and is then ready for further steps such as drying, calcination and ion-exchange.

Any alkali metal ions present in the product of the reaction have to be at least partly removed in order to prepare the catalytically active hydrogen form of Nu-32 and this can be done by ion exchange with an acid, especially a strong mineral acid such as hydrochloric acid or by way of the ammonium compound made by ion exchange with a solution of an ammonium salt such as ammonium chloride. Ion exchange can be carried out by slurrying once or several times with the ion-exchange solution. The zeolite is usually calcined after ion exchange but this may be effected before ion-exchange or during ion-exchange if the latter is carried out in a number of stages. Ion exchange can also be used to replace ions present in the "as made" form of the zeolite by other ions and this ion-exchanged form of the zeolite can also be converted, if desired, to the hydrogen form as described above.

Organic material incorporated in the zeolite during the synthesis can be removed by heating at temperatures up to at least 5500C under atmospheric pressure or by heating at lower temperatures, under reduced pressure. Alternatively, organic material may be removed by dissolution in water or in a suitable organic solvent, if desired during ion-exchange.

Zeolite Nu-32 prepared by the method of the invention is useful as a catalyst and as a sorbent, for example in drying organic compounds. Thus zeolite Nu-32 may be used as a catalyst in the processes of esterification, cracking, hydrocrackirlg, dehydrocyclisation and dehydration reactions, for example the conversion of alkanols to lower olefins.

The zeolite and its method of preparation are illustrated by the following Examples.

Example 1 A synthesis mixture having the following molar composition: 7.95 Na2O : 4.6 (4,4')bipyridyl : Awl203: 30SiO2 : 834H2O : 6.6 S042- was prepared from two solutions.

Solution A was prepared by diluting 2619 of sodium silicate Q-79 (Na2O, 0.01 Al203, 3.7 SiO2,24H20) with 230 g water and stirring in 32.69 of (4,4') bipyridyl.

Solution B was prepared by dissolving 26.4g aluminium sulphate (AI203,3S03,1 6H20) and 1 6.9g (98%) sulphuric acid in 2849 water.

Solution B was stirred vigorously into solution A until homogenous and the mixture was reacted with stirring at 180"C for 3 days in a stainless steel autoclave. The product was filtered and washed with 1 litre of distilled water at about 60"C. The wash was repeated and the product dried at 1 00'C overnight to yield highly crystalline sodium 4,4'-bipyridyl Nu-32 having a molar composition of: 0.7 Na2O 1.5 Q : AI203 : 22 SiO2: 3H20 and an X-ray diffraction pattern as set out in Table 2.

Example 2 The product of example 1 was calcined in air at 550"C for 17 hours and then slurry exchanged at 60"C with 4ml N/1 hydrochloric acid for 1 hour. The dried product was calcined for 3 hours at 4500C and had a molar composition, ignoring hydrogen, of 0.03 Na2O, Al203, 24 SiO2 and X-ray data as shown in Table 2 Example 3 This example was carried out in the same manner as example 1 except that the molar composition of the reaction mixture was 6.370, 11.9 Na2O, Al203, 45Si02, 1800 H20, 9.9 So42 and the weights of reactants used in solutions A and B were (A) 1879 sodium silicate 0-79, 300g water, 21 .4g (4,4'bipyridyl), and (B) 129 aluminium sulphate, 15.1g sulphuric acid, 186g water. The Nu-32 product obtained had the following dried composition: 0.79 Na2O, 2.50, Awl203,32 SiO2, 6H20 and X-ray data as given in table 2.

TABLE 2 Nu-32 as made H Nu-32 Nu-32 as made example 1 example 2 example 3 d(A) I/lo d(A) I/lo d(A) I/lo 6.99 6 6.90 10 6.95 8 6.56 6 6.56 18 6.54 17 4.96 6 4.94 8 4.96 7 4.75 5 4.74 8 4.77 4 4.64 22 4.64 23 4.63 23 4.50 6 4.48 10 4.50 7 4.214 6 4.208 8 4.210 6 4.072 27 4.076 28 4.070 26 3.919 7 3.942 28 3.920 2 3.822 21 3.822 25 3.820 22 3.504 10 3.502 5 3.423 100 3.417 100 3.421 100 3.354 8 3.350 12 3.355 7 3.176 33 3.172 35 3.174 31 3.070 15 3.071 6 3.069 10 2.905 4 2.902 3 2.778 33 2.770 30 2.772 35 2.708 17 2.702 15 2.705 16 2.645 19 2.640 18 2.644 17 2.590 2 2.590 1 2.325 13 2.323 8 2.325 10 2.206 2 2.021 4 2.020 4 2.020 5 1.890 2 1.862 21 1.858 20 1.861 22 Example 4 The product of example 3 was converted into H-Nu-32 as in example 2 and had the following molar composition ignoring hydrogen 0.03 Na2O, AI203, 34 SiO2 Example 5 The reaction mixture used had a molar composition of: 2.1 Na2O : 8.4Q : Al203 : 60SiO2 : 2700 H2O.

51 .4g Aerosil 200 silica were dispersed in a solution of 1 8.7g (4,4') bipyridyl in 6789 water at 60"C. Next 2.85g sodium aluminate (1.22 Na2O, AI2O3, 1.2 H20) and 1 g of sodium hydroxide in 1 5g water were stirred into the silica slurry. The mixture was reacted at 1700C for 5 days and the product obtained was highly crystalline Nu-32 having an as made, dried composition of: 0.85 Na2O :1.9 Q: Awl203: 52 SiO2 :8 H2O.

Example 6 A reaction mixture was prepared having the molar composition: 18.6 Na2O: 10.8Q : Al203 : 70 SiO2 : 2443 H2O: 15.o 5042- where Q is 4,4' bipyridyl. The reaction was carried out as in Example 1 except that the reaction was for 1 day at 1800C and the weights of reactants were: Solution A 148.89 Q-79 sodium silicate, 2979 water, 18.2g (4,4') bipridyl.

Solution B 5.7 g aluminium sulphate, 14g sulphuric acid, 100 g water.

The product obtained, after drying, contained about 40% zeolite Nu-32 and about 60% of zeolite Nu-6(1).

The latter zeolite is described and claimed in the Applicant's European Patent No 54,364.

Sorption Properties of Zeolite H-Nu-32 The sorption properties of H-Nu-32 were examined using the Nu-32 obtained in example 4. Sorption was carried out with the sorbent at 25"C and the sorbate at 0 C. The data, shown in Table 3, suggest that the zeolite has a structure with 8-ring windows with ports of about 3.8A in size.

TABLE 3 Sorbate Time (mins) %w/wsorbed 10 6.4 Water 60 7.6 120 7.8 10 0.2 Methanol 60 0.4 120 0.8 10 0.2 n-hexane 60 0.3 120 0.4 10 0.2 p-xylene 120 0.2 The X-ray data and sorption properties indicate that zeolite Nu-32 is a new zeolite, the X-ray data in particular distinguishing it from all otherzeolites.

Claims (12)

1. A crystalline zeolite material, Nu-32, having a composition (in terms of mole ratios of oxides) expressed by the formula: 1.0 + 0.3 MznO: Y2Q3: 15 to 70 XO2: 5 to 25 H2O wherein M is at least one cation of valency n, X is silicon and/or germanium, Y is one or more of aluminium, iron, chromium, vanadium, molybdenum, arsenic, anitmony, manganese, gallium or boron and H20 is water of hydration additional to water notionally present when M is H, and having an X-ray powder diffraction pattern substantially as set out in Table 1 (as determined by standard technique using copper Ka radiation).

2. A crystalline zeolite material, Nu-32, as claimed in claim 1 wherein R is or includes an alkali metal cation, ammonium, hydrogen or a nitrogen containing organic cation.

3. A crystalline zeolite material, Nu-32, as claimed in claim 1 or 2 having, as freshly made, a molar composition 0.6 to 1.1 M2O: 0.3 to 3.0 Q: Y203: 15 to 70 XO2: 2 to 25 H2O where M is alkali metal, ammonium or hydrogen and Q is nitrogen - containing organic cation.

4. A crystalline zeolite material, Nu-32 as claimed in any one of claims 1 to 3 and having an X-ray powder diffraction pattern substantially as shown in Table 2.

5. A method of preparation of crystalline zeolite material, Nu-32 as defined in any one of claims 1 to 4, which comprises reacting an aqueous mixture containing sources of at least one oxide XO2, at least one oxide Y203 and a 4,4'-bipyridyl compound, the reaction mixture having the molar composition.

XO2N203 in the range 25 to 70 OH-/XO2 in the range 0.05 to 0.2 H2O/XO2 in the range 0 to 60 SIX02 in the range 0.05 to 0.3 Z-/XO2 in the range 0 to 0.5 wherein Q represents the 4,4' - bipyridyl compound, X and Y have the meanings as hereinbefore defined, and Z represents an acid radical.

6. A method as claimed in claim 5 wherein the reaction mixture has a molar composition in which X02/Y203 is in the range 30 to 60 OH-/XO2 is in the range 0.07 to 0.10 H2O/XO2 is in the range 20 to 45 O/XO2 is in the range 0.08 to 0.15 Z-/XO2 is in the range 0 to 0.32

7. A method as claimed in claim 5 or 6 wherein the bipyridyl compound is partially of fully alkylated.

8. A method as claimed in claim 5 or 6 wherein the bipyridyl compound is 4,4'bipyridyl.

9. A method as claimed in any one of claims 5 to 8 wherein the reaction mixture contains an alkali metal compound.

10. A method as claimed in claim 9 wherein the alkali metal is sodium or potassium.

11. A catalyst comprising zeolite Nu-32 as defined in any one of claims 1 to 4.

12. A catalytic process employing the catalyst claimed in claim 11.