Crystalline Aluminosilicate and Process for Its Production

The invention is directed to a process for the production of the new crystalline aluminosilicate PZ 1, the aluminosilicate PZ 1 itself, the production of aluminosilicate PZ 2 from aluminosilicate PZ 1, the aluminosilicate PZ 2 itself as well as the use of aluminosilicate PZ 2 as a catalyst.

The subject matter of the invention is a process for the production of the crystalline aluminosilicate PZ 1 which is characterized by carrying out the crystallization from an aqueous SiO.sub.2, Al.sub.2 O.sub.3 and alkali containing synthesis mixture in the presence of an organic template compound of the general formula R.sub.3 P--(CH.sub.2).sub.n --PR.sub.3 X.sub.2.

In the general formula R.sub.3 P--(CH.sub.2).sub.n --PR.sub.3 X.sub.2, R is lower alkyl, e.g. methyl, ethyl propyl and/or butyl, n is 2, 3, 4, 5, and/or 6 and X is Br and/or I.sup.-.

In a preferred illustrative form of the invention there can be employed the template compound Bu.sub.3 P--(CH.sub.2).sub.3 --PBu.sub.3 Br.sub.2 and/or Bu.sub.3 P--(CH.sub.2).sub.3 --PBu.sub.3 I.sub.2.

The crystallization can be carried out in a synthesis mixture which has the following composition:

whereas T means template compound.

Advantageously the crystallization is carried out in such manner that the synthesis mixture is stirred at autogeneous pressure in an autoclave at a temperature between 90.degree. and 200.degree. C. until crystals are formed.

The aluminosilicate produced by means of the process of the invention carries the designation PZ 1. It can be characterized by its composition, its adsorption behavior, its crystal form, and its X-ray diffraction pattern.

The aluminosilicate PZ 1 has the following chemical composition:

Scanning electron microscope photographs point to agglomerates of platelets growing together (see FIG. 1).

The X-ray diffraction pattern (Table 1) shows essentially the following lines:

It was measured according to standard methods with a scintillation counter-diffractometer with CuK.alpha. radiation. d[.ANG.] designates the interplanary distances and I/Io their relative intensities.

Adsorption measurements (20.degree. C., 50% relative humidity lead to the following results (data in grams of adsorbed substance per gram of silicate):

If the aluminosilicate PZ 1 is treated with a dilute acid, preferably a mineral acid, as for example sulfuric acid or hydrochloric acid or subjected to an ion exchange with NH.sub.4 Cl and subsequent calcinization, then there is formed a new crystalline aluminosilicate PZ 2, whose X-ray diffraction pattern (Table 2) shows a change in structure.

Scanning electron microscope photographs on the contrary do not detect any change in crystal form or size in the passage PZ 1.fwdarw.PZ 2.

The aluminosilicate PZ 2 has the following analytical composition:

Adsorption experiments at 20.degree. C. and 50% relative humidity led to the following results:

(data in grams of adsorbed substance per gram of silicate).

The aluminosilicate PZ 2 is suitable for use as a catalyst, especially for converting alcohols into hydrocarbons, e.g. converting an alkanol such as methanol or ethanol to a hydrocarbon mixture rich in olefins at a temperature of 400.degree. C. Generally there can be used the conditions and temperature ranges employed with zeolite ZSM 5 in converting lower alcohols to hydrocarbon mixtures as described by Meisel et al., Chemtech 6, 86 (1976)

From the literature (H. P. Eugster, Science Vol. 157, pages 1177-1180 (1967) there is known a mineral layered silicate whose X-ray diffraction pattern is similar to that of PZ 1. However, there are exhibited clear differences at many interplanar distances.

The mineral layered silicate, magadiite, is described as sodium silicate hydrate of the formula NaSi.sub.7 O.sub.13 (OH).sub.3 3H.sub.2 O, while for the crystallization of PZ 1 an aluminum compound must be present. Upon increasing the SiO.sub.2 /Al.sub.2 O.sub.3 ratio above about 250:1 there is no longer obtained PZ 1 but another product.

In the same literature there is also described the conversion of magadiite into a compound SH whose X-ray diffraction pattern is similar to that of PZ 2, but likewise exhibits clear differences. Besides in the above-mentioned literature there is expressly described the conversion of SH into magadiite by treating with Na.sub.2 CO.sub.3 or NaOH. In the treatment of PZ 2 with these compounds to be sure analytically a sodium absorption is detected but there is no structured change PZ 2.fwdarw.PZ1 as can be readily detected by the adsorption of the X-ray diffraction pattern. From Audeh U.S. Pat. No. 4,285,922 there is known the production of a nonidentified material as byproduct in the crystallization of ZSM 5 which exhibits an X-ray diffraction pattern similar to PZ 1. However, this material 3 forms preferably at SiO.sub.2 /Al.sub.2 O.sub.3 ratios which are greater than 500:1, and at least are greater than 300:1. PZ 1 on the contary exists at mole ratios between about 50 and about 250:1. A further decisive difference is in the behavior in ion exchange. The X-ray diffraction pattern given in Audeh U.S. Pat. No. 4,285,922 is characteristic for all products obtained through ion exchange, while with PZ 1 in the ion exchange, for example, with NH.sub.4 Cl, there is a rearrangement to PZ 2, for which there can be observed a changed X-ray diffraction pattern.

Unless otherwise indicated all parts and percentages are by weight.

The processes can comprise, consist essentially of, or consist of the stated steps with the recited materials.

2.4 grams of alumina trihydrate were dissolved in 50 ml of a 6.2N NaOH solution and added to a suspension of 120 grams of precipitated silica (89% SiO.sub.2) in a solution of 25 grams of Bu.sub.3 P--(CH.sub.2).sub.3 --PBu.sub.3 Br.sub.2 in 750 ml of water. This mixture was stirred for 20 minutes at 50.degree. C., transferred into a steel autoclave and stirred for 310 hours at 100.degree. C. After the end of the crystallization the crystals were separated off by filtration, washed with water and dried for 12 hours at 120.degree. C.

The procedure was analogous to Example 1 but in place of alumina trihydrate there was employed the same amount of sodium aluminate, the amount of NaOH reduced to 3.5 grams and stirring was for 200 hours at 130.degree. C.

In this example in distinction from Example 1 there were used 4.2 grams of alumina trihydrate, 16.5 grams of NaOH and 100 grams of precipitated silica and stirring was for 50 hours at 160.degree. C.

The amounts employed were:

It was crystallized for 14 hours at 175.degree. C.

In Examples 1 to 4 there were obtained well crystallized aluminosilicate PZ 1.

50 grams of PZ 1 from Example 2 were stirred in 500 ml of 1N HCl for 2 hours at 80.degree. C., filtered off, washed with water until neutral and dried for 17 hours at 120.degree. C.

30 grams of PZ 1 from Example 2 were stirred for 2 hours at 80.degree. C. with 300 ml of 5N NH.sub.4 Cl solution, filtered off, washed with water until Cl.sup.- free, dried for 4 hours at 120.degree. C. and calcined for 16 hours at 550.degree. C.

Examples 5 and 6 gave well crystallized aluminosilicate PZ 2.