GB1049891A - Aluminosilicate catalyst - Google Patents

Abstract

A crystalline aluminosilicate has a silica/alumina ratio in excess of 3 and has uniform pores between 6 and 15 <\>rA in diameter, the cation of the aluminosilicate being a metal below sodium in the electromotive series (as defined in the Handbook of Chemistry and Physics, 43rd edition, published by the Chemical Rubber Publishing Company) or calcium, an organic nitrogen base or a mixture thereof with each other or with hydrogen and/or ammonium, the alkali metal content of the aluminosilicate being less than 3% by weight. The aluminosilicate is prepared from preferably a Y zeolite by base exchange with solutions containing the appropriate cations, particularly calcium, magnesium, rare earth metal, rare earth metal plus hydrogen or manganese ions, to replace at least 70% of alkali metal ions of the zeolite. The aluminosilicate may be used as a cracking catalyst, preferably dispersed in a proportion of 1 to 90% by weight in a matrix of a binding agent, the composition optionally containing an additive to increase its porosity. The binding agent may be an inorganic oxide gel, e.g. alumina, silica, zirconia, hafnia, thoria, titania or mixtures of these, particularly co-gels containing at least 55% silica with at least one of the others or beryllia, or it may be an activated metal powder, e.g. aluminum or iron-containing alloys, a clay, e.g. montmorillonite or kaolinite, charcoal, graphite, mullite, kieselguhr, activated carbon, bauxite or activated carbon. Mixture of aluminosilicate and binder may be achieved by ball-milling, preferably under water, or the aluminosilicate may be dispersed in finely divided form, i.e. less than 40 microns, in a hydrosol or hydrogel, or it may be added to one of the reactants used in forming the hydrosol, or it may be mixed with the reactants in e.g. a mixing nozzle. The hydrogel is broken up into beads by extrusion, casting or pelleting, or the hydrosol may be introduced into oil wherein the globules set to a hydrogel in the form of microspheres of 20-300 microns which pass to an underlying aqueous layer and are removed. Base exchange of the starting zeolite may take place before or after mixing with the binder. In the former case, a subsequent base exchange may be required to remove alkali metal derived from the binder. The porosity-imparting additive, up to 40% by weight of the composition, and of particle size 1-40 microns, may be clay, alumina, zircon, barytes, carbon, wood flour, silica, magnesia, recycle catalyst fines or spent catalyst fines. In subsequent preparative treatment, or during use, combustible additives such as carbon or wood flour may be removed.