CATALYTIC DISPROPORTIONATION OF CO IN THE ABSENCE OF HYDROGEN - ENCAPSULATING SHELL CARBON FORMATION

The catalytic disproportionation of CO in the absence of H-2 resulted in carbon depositing as a lamellar form of graphite on the surface of the catalyst metal particles, as opposed to the filaments more commonl y discussed in the literature. Carbon deposition on supported Ni and C o catalysts was investigated using TEM. The mechanism for this form of carbon deposition, and the tendency for specific numbers of layers of carbon to deposit on the specific catalyst metals, is discussed. It i s stressed that some form of hydrogen must be present in order for fil aments to form. Metal dusting of the catalyst caused by filament growt h might be avoided by lamellar deposition, improving catalyst longevit y. For regeneration of catalytic activity, the Boudouard reaction was used to remove deposited carbon from the catalyst surface.