CHARACTERIZATION OF A SULFUR-RESISTANT METHANATION CATALYST BY XPS

A Ni-Cr on MgSiO//3 catalyst has been developed by United Catalysts, Inc. This catalyst converts 60% of the input CO to CH//4 after a heavy presulfiding treatment that reduces the CO conversion of conventional catalysts to less than 10%. The unsulfided conversion rate is better than 95%. X-ray photoemission spectra obtained from a series of untreated, sulfided, and methanation-tested Ni and Ni-Cr on MgSiO//3 catalysts show the presence of nickel sulfide in catalysts which are deactivated by the sulfiding. Both nickel sulfide and nickel sulfate are found in the catalysts that retain appreciable methanation activity. The amount of sulfur in the active catalysts is also appreciably less than in the inactive catalysts. The relationship between the resistance to sulfur poisoning and the presence of Cr and MgSiO//3 is discussed.