Highly efficient Ni/ZrO2 catalysts prepared via combustion method for CO2 methanation

Abstract

The 15wt% Ni/ZrO2 catalyst was firstly synthesized using urea as the combustion medium, which shows high catalytic performance for CO2 methanation due to its high reducibility and Ni dispersion, small Ni particle size and excellent CO2 adsorption capacity. The CO2 conversion of Ni/ZrO2 prepared by the urea combustion method achieves 60% while the conversion of Ni/ZrO2 using n-propanol as the combustion medium is less than 13% at 300°C, 0.1MPa and a WHSV of 48,000mL·g−1·h−1. A series of catalysts were synthesized using different combustion mediums including ethanol, n-propanol, urea, glycol and glycerol. The prepared catalysts were characterized by BET, ICP-OES, XRD, H2-TPR, H2-TPD and CO2-TPD. The results illustrate that the combustion mediums significantly affect the catalytic pore structure, interaction between active metal and support, Ni dispersion, Ni particle size, the crystal structure of ZrO2 and CO2 adsorption capacity. In addition, the synergistic effect between nickel and mediums leads to a total phase transformation of zirconia from m-ZrO2 to t-ZrO2. The 15Ni/ZrO2 catalyst prepared by urea combustion method exhibits not only higher activity but also better stability due to its smaller Ni particle size and better resistance to carbon deposition than the one prepared by impregnation method.