Metal Catalyzed Gasification of Graphite

Abstract

One of the most interesting and intriguing topics in the field of heterogeneous catalysis is the mechanism by which metallic particles influence the gasification of graphite. The gasification of carbon by oxidizing gases is often the limiting factor in the performance of graphite structures at high temperatures. Currently, one of the most important areas involves the function of metals in the removal of carbonaceous deposits from spent catalysts and steam cracker tubes. Supported metal catalysts are employed in a variety of commercial hydrocarbon conversion processes. Such catalysts consist, in general, of small metal crystallites (0.5 to 2.5 nm diameter) dispersed on nonmetallic oxide supports. In the absence of such poisons as sulphur, arsenic, phosphorous, and heavy metals, the major way in which the catalyst loses activity is due to accumulation of carbonaceous residues on its surface. Catalyst regeneration is usually achieved by gasification of the deposit in an oxidizing environment at about 500°C. The efficiency of this process is variable and so there is an increasing demand to learn more about the process so that gasification can be optimized.