Effect of preparation condition on catalytic performance of Ni/ZrO₂-SiO₂ for methanation of coal gas

Ni/ZrO₂-SiO₂ catalysts with 6% Ni loading amount were prepared by impregnation. The ZrO₂-SiO₂ support was also synthesized by impregnation. Effects of pH value of the impregnating solution and calcination temperature of support and catalyst on activities of Ni/ZrO₂-SiO₂ catalysts were investigated. The catalysts were characterized using XRD,TPR and SEM measurements. Ni/ZrO₂-SiO₂(S5) catalyst exhibited excellent catalytic activity with 100% of CO conversion, 1.8% of CO₂ conversion and 16.6 (mmol·h^-1·g^-1) of CH₄ formation rate. The preparation conditions were as follows:pH value of the impregnating solution, 8.0～9.0, calcination temperature of support and catalyst, 550 ℃ and 450 ℃.The mathanation activity of Ni/ZrO₂-SiO₂ was strongly influenced by the ZrO₂ phase change. The catalyst with tetragonal zirconia showed higher catalytic activity. The increase of pH value of the impregnating solution was in favor of forming small tetragonal zirconia. The calcination temperature of support influenced the grain size and the dispersity of NiO, unsuitable temperature might lead to ill-fitted grain size and aggregation. Exorbitant calcination temperature could weaken interaction between NiO and the support, and lowered the dispersity of NiO.