Deactivation studies of nickel catalysts used in the methanation of carbon monoxide

Four laboratory prepared catalysts (Ni/Al2O3, NiNaY‐uncalcined, NiNaY‐calcined, NiCaY‐calcined) and a commercially available catalyst G‐87 were studied for their deactivation behavior over a period of 24 h at 573 k for various H2/CO ratios (3.1, 3.8, 6.4 and 24.5). The results indicated that the activities did not change much with time at H2/CO ratios of 3.8 and higher. Detailed measurement of catalytic activities, crystallite sizes, metal areas and carbon depositions were made at an H2/CO ratio of 3.1. These measurements indicated that sintering and carbon depositions occurred on all the catalysts thus deactivating the catalysts. An attempt has been made to explain the catalytic behavior in terms of crystallite size changes and carbon depositions. Limited regeneration studies of G‐87 and NiNaY‐calcinated catalysts have also been done.