Nickel catalyst deactivation in the steam-carbon reaction

Nickel deactivation during steam gasification of carbon is shown to be two types which depend upon the chemical nature of the carbon. For graphite, deactivation is moderate and may be attributed either to catalyst clustering or to effects of the carburization of the nickel. With less-ordered carbons, like Spherocarb, deactivation is severe and rapid. The catalyst particles apparently lose surface area due to encapsulation by a graphite overlayer. Dual-bed gasification indicates that the carbon substrate releases hydrocarbon species which subsequently decompose on the nickel. Analogous results are obtained during the CO₂ and H₂ gasification reactions.