PT/SAPO-5 AND PT/SAPO-11 AS CATALYSTS FOR THE HYDROISOMERIZATION AND HYDROCRACKING OF N-OCTANE

n-Octane hydroisomerization and hydrocracking on SAPO-B and SAPO-11 catalysts containing 0.5 wt.% Pt have been investigated in a flow reactor over a wide range of temperatures (573-708 K) and pressures (atmospheric, 3 and 5 bar). These studies have shown that hydroisomerization is a function of the total conversion. The primary products obtained with n-octane were the monobranched isomers. Multibranched feed isomers and cracked products were formed in subsequent reactions. In all cases, hydrogen pressure had a strong influence on the activity and time-on-stream deactivation. Hydroisomerization can be considered to be the primary reaction, with hydrocracking occurring to a significant extent only at higher conversions (>40% for Pt/SAPO-5 and >65% for Pt/SAPO-11). The selectivity patterns found in these molecular-sieve catalysts are interpreted in terms of a series of reaction pathways incorporating both confinement effects and shape selectivity factors.