Chrysocolla as a Methanation Catalyst Support

Abstract

The kinetic properties of nickel supported on chrysocolla (CHR) and nickel—copper mixtures supported on silica were measured by steady-state kinetics (carbon monoxide hydrogenation), temperature-programmed desorption (carbon monoxide, hydrogen), and temperature-programmed reaction (carbon monoxide and carbon hydrogenation). Leached chrysocolla, a silica-like material containing 7.1% copper, is shown to be an effective catalyst support; NI/CHR has methanation activity and adsorption properties (hydrogen, carbon monoxide) that are similar to Ni/SiO 2. The Ni/CHR catalyst has a much higher selectivity to methane formation, however, and a lower activation energy. The copper in the CHR support does not appear to affect the catalyst properties and thus apparently does not interact with the nickel. Copper in Cu Ni catalysts decreases the turnover number for methanation, the amount of hydrogen adsorption, the strength of hydrogen binding to the surface, and the rate of carbon monoxide disproportionation. Copper also increases higher hydrocarbon selectivity at higher temperature, though the temperature at which this occurs depends significantly on the support. The rate of carbon hydrogenation, however, is relatively independent of the presence of copper. Good agreement was obtained between carbon monoxide hydrogenation kinetics measured by steady-state reaction and by temperature-programmed reaction.