The tunneling action of group VIII metal particles in catalyzed graphite hydrogenation

A new catalyst action in catalyzed graphite hydrogenation, termed tunneling, is observed and studied for Pt, Ni, and Ru. The metal particles undergo tunneling in the a direction of graphite (parallel to the basal plane), gasifying carbon. The linear speed of tunneling is independent of particle size. The sequential steps in the reaction are CC bond breakage and dissolution of carbon into the metal at the leading-edge carbon-metal interface, diffusion of carbon in metal, and reaction between C and H on metal surface. The last step is rate limiting, and is a common step for deep-layer channeling, monolayer channeling, as well as the methanation reaction. Both tunneling and monolayer channeling actions are at least as important as deep-layer channeling in the overall rate for graphite hydrogenation.