The activity, stability, and selectivity of a series of bifunctional P
t/SAPO-5 and Pt/SAPO-11 catalysts containing 0.5 wt% platinum, were co
mpared for n-hexane transformation at 300-425 degrees C and atmospheri
c, 3- and 5-bar hydrogen pressures. Hydrogen pressure had a strong inf
luence on the activity, isohexane selectivity, and time-on-stream deac
tivation. Isomerization to isohexanes was the major reaction in both c
ases. However, Pt/SAPO-5 shows high activity and higher isohexane sele
ctivity than Pt/SAPO-11 catalyst. The selectivity patterns found in th
is 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 ob
served product distribution.