Features of Carbon-supported Metal Catalysts for Vapor Phase Carbonylation of Methanol and Related Compounds.

Abstract

Catalytic activities of active carbon (A.C.) supported group 8-10 metals catalysts for vapor phase carbonylation of methanol were found to be in the order as follows: Rh>Ir>Ni>Pd>Co>Ru>Fe. A plot of the relation between the catalytic activity and the affinity of the metals for halide ion displayed a volcano shape. The rate determining step of the reaction is discussed on the basis of this affinity.A variety of metal species of group 5-16, such as V, Cr, W, Mn, Re, Cu, Cd, Ga, Ge, Sn, Pb and Se, showed the catalytic activity in the vapor phase carbonylation of methanol, only when they were supported on A.C. Among them, tin and lead showed comparatively high activities.Over Ni/A.C. catalyst, methanol was first carbonylated directly to methyl acetate or via dimethyl ether, then carbonylated again to acetic anhydride and finally hydrolyzed quickly to acetic acid. Overall kinetics were explored to simulate product profile, based on the reaction network mentioned above.Vapor phase carbonylation was greatly enhanced by coexistence of hydrogen when the metal had a high affinity for halogen, whereas, it was inhibited over such metal having weak affinity.