GB1049892A - Catalyst composition - Google Patents

Abstract

A catalyst composition comprises a crystalline aluminosilicate having a silica/alumina ratio in excess of 3 and uniform pores between 6 and 15A DEG in diameter and containing cations below sodium in the electromotive series, or calcium, ammonium, hydrogen or organic nitrogen base ions, or mixtures thereof, and less than 3% by weight of alkali metal ions. The aluminosilicate in a proportion of 1-90% by weight is suspended in and distributed throughout a matrix of a binding agent, and the composition optionally contains an additive to increase its porosity. The aluminosilicate is prepared by replacing at least 70% of the alkali metal ions in e.g. a V-zeolite by base exchange with a solution containing the appropriate cations, particularly calcium, rare earth, magnesium, manganese, hydrogen and/or ammonium ions. The binder may be an inorganic oxide gel, e.g. alumina, silica, zirconia, magnesia, halfnia, thoria, titania or mixtures of these, particularly co-gels containing at least 55% of silica with at least one of the others or beryllia, or it may be an activated metal powder e.g. aluminium or iron containing alloys, a clay, e.g. montmorillonite or kaolinite, charcoal, graphite, mullite, kieselguhr, activated carbon, bauxite or silicon carbide. Mixture of aluminosilicate and binder may be accomplished 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 or more of the reactants used in forming the hydrosol, or it may be mixed with the reactants in e.g. a mixing nozzle. The hydrogel formed may be broken up to desired size e.g. 1/16 " - 1/8 " by extrusion, casting or pelleting, or where microspheres of 20-300 microns are required, the hydrosol may be introduced into e.g. oil, where the hydrosol globules set to a hydrogel and pass to an underlying aqueous layer and are removed. Base exchange may take place before or after mixing with the binder, and in the former case, a further base exchange may be required subsequently to remove alkali metal ions, e.g. derived from silicates in the binder. The porosity imparting additive, up to 40% by weight in the composition, and of particle size range 1-40 microns, may be clay, alumina, zircon, barytes, carbon, wood flour, silica, magnesia, recycle catalyst fines or spent cracking catalyst fines. In subsequent preparative treatment, or during use, combustible additives, e.g. carbon or wood flour, may be removed. The final composition is washed, dried at ambient temperature, or better at between 150 and 600 DEG F. for 4-48 hrs, and activated by heating e.g. in air at 500 DEG - 1500 DEG F. for 1-48 hrs. Selectivity is improved by exposing the composition to an atmosphere containing 5% steam at a temperature between 400-1450 DEG F. and a pressure between atmospheric and 500 psig for 2-100 hrs.