Shape selective catalyst from zeolite alpha and use thereof

Claim 1

A catalyst produced by a method for synthesizing crystalline alumino-silicate zeolite Alpha containing platinum-group metal within the zeolite pores which comprises the steps of preparing a reaction mixture containing sources of sodium oxide, tetramethylammonium oxide, aluminum oxide, silicon dioxide, a cationic platinum-group metal complex and water and having a composition, in terms of mole ratios of oxides, falling within the following ranges: SiO 2 /Al 2 O 3 =4.0-12.0 H 2 O/(Na 2 O+R 2 O)=15.0-40.0 (Na 2 O+R 2 O)/Al 2 O 3 =2.0-7.0 Na 2 O/(Na 2 O+R 2 O)=0.2-0.75 M/Al 2 O 3 =10 -6 -0.06 wherein R is a tetramethylammonium cation and M is a platinum-group metal, aging said mixture for from about 2 hours to about 100 hours at a temperature of from about 10° C. to about 70° C., and then heating said mixture at a temperature of from about 80° C. to about 150° C. until crystals of said zeolite are formed, and which comprises the further step of replacing, at least in part, the original sodium cations of said zeolite by ion exchange with a cation or a mixture of cations selected from the group consisting of hydrogen and metals from Groups IIA, IVA, IB, IIB, IIIB, VIB, and VIIB of the Periodic Table of Elements, and then heating said zeolite at a temperature from 480° C. to about 820° C.