Enhancing the formation of nickel catalysts (111) crystal plane and CO2 methanation reactivity by external magnetic field

Abstract

Nickle catalysts with acicular nanostructures are prepared by chemical reduction under different external magnetic fields. The characteristics reveal by XRD and HR-TEM illustrated that the growth of the Ni (111) plane is enhanced with the increasing in external magnetic field intensity. The shape of the Ni catalyst changes from particle to wire when the external magnetic field was greater than 1000 G. The TOF of catalysts increases linearly as the ratio of the (111)/(200) crystal planes increases, according to TPR and CO chemisorption experiments. The Ni catalyst prepared under 500 G external magnetic field shows good catalytic performance for CO2 methanation below 200 °C. Up to 99% conversion and CH4 selectivity of CO2 is obtained at 200 °C with H2/CO2 = 4.5 and GHSV ~ 1,000 h−1. Furthermore, the catalysts remine unchanged after 120 h at 180 °C. The activation energy of CO2 methanation on Ni catalysts is 84.7 kJ/mol.