COMPARATIVE EFFECT OF ORGANOSULFUR COMPOUNDS ON CATALYSTS FOR THE N-HEPTANE ISOMERIZATION REACTION AT MEDIUM PRESSURE - MO2C-OXYGEN-MODIFIED, MOO3-CARBON-MODIFIED, PT GAMMA-AL2O3, AND PT/BETA-ZEOLITE CATALYSTS/

Molybdenum oxycarbide formed from oxidized Mo2C or reduced MoO3 is an active and very selective catalyst for the isomerization of n-heptane compared to supported Pt. Deactivation experiments performed on the ca talysts with different concentrations of organosulfur compounds show t hat molybdenum oxycarbide exhibits a very high resistance to deactivat ion, whereas with platinum-based catalysts deactivation occurs even at low sulfur concentration in the feed. Deactivation can be slowed by i ncreasing the hydrogen partial pressure from 6 to 20 bar. In these con ditions, the molybdenum oxycarbide shows no deactivation with sulfur c oncentrations up to 120 ppm of S. In addition, the deactivated molybde num catalysts can be easily regenerated by mild oxidative treatment un der flowing air at atmospheric pressure and 723 K for 2 h followed by a reactivation period under the hydrogen and hydrocarbon mixture.