A KINETIC FEATURE OF CATALYTIC GASIFICATION OF CARBONS - ACTIVATION OF NICKEL AND IRON CATALYSTS DURING GASIFICATION

A unique rate increase with time in catalytic gasification of carbons by hydrogen was examined as to its dependence on reaction conditions, catalyst species, carbon substrates and so on, to clarify the reason of the phenomenon. It was marked with a porous substrate at relatively low temperature when nickel or iron was the main catalyst. By heating carbon substrate in hydrogen at 850 to 900°C before catalyst impregnation, the rate increase disappeared. Comparing several possible explanations, it is concluded that the rate increase with conversion is due to the recovery of metal catalyst from deactivation caused by heteroatoms on carbon surface. The hydrogen pretreatment resulted in a high rate of gasification with hydrogen as well as steam. © 1990.