Isomerization of n-Pentane and Other Light Hydrocarbons on Hybrid Catalyst. Effect of Hydrogen Spillover

摘要

Isomerization of n-pentane was carried out over Pt-containing zeolite catalyst with a flow-type reaction apparatus under atmosphere. The typical reaction conditions were 230-300℃, 1 atm, H_2-C_5H_(12) = 9/1 (mole ratio), W/F 10.0 g h/mol. Thermodynamic equilibrium conversion of about 70% at 270℃ could be reached on Pt/HZSM-5 (supported catalyst), Pt-hybrid (a physical mixture of Pt/SiO_2 and HZSM-5 powders) catalysts. The isomerization selectivity was higher for Pt-hybrid catalyst than for Pt/HZSM-5. Pt-hybrid catalyst showed higher isomerization activity over wider temperature and pressure ranges than did Pt/HZSM-5. The effect of spilled-over H is considered to play an important role in the regeneration of Br0nsted acid site and the stabilization of an i-C_5~+ intermediate. A reasonable reaction mechanism is proposed.