Mechanochemical synthesis method for the preparation of mesoporous Ni–Al2O3 catalysts for hydrogen purification via CO2 methanation

Ni–Al2O3 catalysts with different Ni percentages were prepared by a simple mechanochemical method, and the catalysts were employed in the methanation of CO2 for hydrogen purification. BET, XRD, EDS, SEM, TPR, TGA, and FTIR analyses were conducted to identify the chemicophysical characteristics of the prepared samples. The results confirmed that the simple mechanochemical synthesis method was operational and effective to synthesize the Ni catalysts with a high BET area (175.4–296.5 m2/g). With an increase in Ni percentage from 5 to 20 wt%, the size of the Ni particle increased from 2.7 nm to 7.8 nm, and also the BET area decreased from 296.5 to 175.4 m2/g. According to the TPR results, the reducibility of the samples improved with the increase of Ni content. Based on the catalytic performance results the catalyst with 15 wt% Ni and the BET area of 183.2 m2/g exhibited the best performance in methanation of CO2 (75.2% conversion of CO2 and 96.8% selectivity of CH4 at 400 °C). The 15Ni–Al2O3 catalyst showed stable stability during 10 h. CO methanation was investigated on the 15 wt%Ni–Al2O3 catalyst and the results showed that CO completely converted to CH4 at 300 °C.