HYDROISOMERIZATION OF N-ALKANES OVER PT-SAPO-11 AND PT-SAPO-31 SYNTHESIZED FROM AQUEOUS AND NONAQUEOUS MEDIA

The acidic and catalytic properties of the medium pore molecular sieve s SAPO-11 and SAPO-31 synthesized by two different routes [from aqueou s and nonaqueous (ethylene glycol) medial are compared. Samples synthe sized from the nonaqueous medium possess more acidity (due to higher s ubstitution of P5+ by Si4+ and consequent lower concentration of silic a islands) and larger hydroisomerization activities and selectivities. The molecular sieves, after loading 0.5 wt % Pt, were used as catalys ts for isomerization of n-hexane, n-octane, and n-hexadecane. Reaction s at the pore mouth at the external surface are more predominant in th e case of SAPO-31 than SAPO-11.