HYDROISOMERIZATION AND HYDROCRACKING OF N-HEXANE ON PT/SAPO-5 AND PT/SAPO-11 CATALYSTS

The activity, stability, and selectivity of a series of bifunctional Pt/SAPO-5 and Pt/SAPO-11 catalysts containing 0.5 wt% platinum, were compared for n-hexane transformation at 300-425 degrees C and atmospheric, 3- and 5-bar hydrogen pressures. Hydrogen pressure had a strong influence on the activity, isohexane selectivity, and time-on-stream deactivation. Isomerization to isohexanes was the major reaction in both cases. However, Pt/SAPO-5 shows high activity and higher isohexane selectivity than Pt/SAPO-11 catalyst. The selectivity patterns found in this class of molecular sieve catalysts are well interpreted in terms of a series of reaction pathways incorporating both confinement effects and shape selectivity factors as being important in determining the observed product distribution.