Enhancement of methanation activity by ammonia-water vapor treatment at the stage of catalyst-metal salt supported on a carrier

Abstract

In the course of catalyst preparation by impregnation of a porous support with catalyst-metal salts, an NH 3-H 2O vapor (AW) treatment was performed before the decomposition of the salts. Salts of various Group VIII metals, and mixed salts of an iron-group metal and lanthanum, were used. For Ni(N0 3) 2, Ni(N0 3) 2-La(N0 3) 3, Ni(CH 3COO) 2 and Co(N0 3) 2-La(N0 3) 3, the resulting catalyst exhibited higher methanation activities as a result of the AW treatment. In these cases, an ammonium complex was formed with gelatinous eduction and the decomposition temperature decreased by about 20°C, resulting in a higher dispersion of catalyst particles. On the other hand, in the cases of NiCl 2, H 2PtC1 6 and PdCl 2, the methanation activities of the resulting catalysts were decreased by the AW treatment. In these cases, the ammonium complex formed larger and better defined crystals which produced larger catalyst particles of low catalytic activity.