Patent ID: 6300537
Filing Date: 2001-10-09
Classification: B01J,C01B,C10G,Y10S

Abstract:
A process for selectively producing C.sub.2 to C.sub.4 olefins, the process comprising contacting, under catalytic conversion conditions, a naphtha containing paraffins and olefins with a catalytically effective amount of a catalyst composition containing a molecular sieve with a framework tetrahedra of silicon, aluminum, and phosphorus, the molecular sieve having a total silicon amount ranging from about 4 molar percent to about 20 molar percent; having a total aluminum amount ranging from about 40 molar percent to about 55 molar percent; and having a total phosphorus amount ranging from about 30 molar percent to about 50 molar percent, the molar percents being based on the total amount of aluminum, phosphorus, and silicon present in the composition; having the topology AEL; and being isostructural with conventional SAPO-11, wherein(a) the silicon present in the molecular sieve and the conventional SAPO-11 is distributed among silicon sites in the framework tetrahedra, each site having a first, a second, a third, and a fourth nearest neighbor position, and each nearest neighbor position being independently occupied by one atom selected from silicon and aluminum, and(b) the molecular sieve has a substantially smaller number of silicon sites having silicon atoms among all four nearest neighbor positions than the conventional SAPO-11 having the same total silicon amount.