Effect of ZrO₂ promoter on the catalytic activity for CO methanation and its adsorption performance of the Ni/SiO₂ catalyst

The catalytic activities for CO methanation and adsorption performances of the Ni/SiO₂ and Ni/ZrO₂-SiO₂ catalysts were investigated by a continuous flowing microreactor apparatus and in-situ diffuse reflectance fourier transform infrared spectroscopy. The results showed that CO was completely transformed at 200℃ under the reaction conditions: CO 1%、GHSV 5000h^-1 and an atmosphere pressure over the Ni/ZrO₂-SiO₂ catalyst, while under the same reaction conditions the CO conversion was only 35% and CO was not completely transformed until 270℃ over the Ni/SiO₂ catalyst, which suggested the catalytic activity of the Ni/ZrO₂SiO₂ catalyst increased with the addition of ZrO₂ promoter. Meanwhile, the addition of ZrO₂ promoter enhanced the adsorption capacity of the Ni/ZrO₂-SiO₂ catalyst for CO, and that in the presence of H₂ a larger amount of bridged carbonyl hydride formed over the Ni/ZrO₂-SiO₂ catalyst at lower temperature, resulting in the increase of its catalytic activity. In CO methanation reaction, the breaking of C—O bond over those catalysts was via multi-hydrogen carbonyl hydride rather than via direct breaking.