Rice husk derived biochar as support for Ni based catalysts in CO2 methanation: A study on biochar activation

Waste derived biochars are becoming fundamental carbonaceous sources to be used as support in catalysis, especially after activation to improve their features. CO2 methanation is a strategic process for energy transition. However, it requires better selectivity and economic feasibility. This can be done by acting on the catalytic system. In this article, a biochar from rice husk biomass was obtained by pyrolysis and activated in two different physical ways (water vapor and CO2). The activated biochars were used to prepare CO2 methanation catalysts with Ni 10 wt%. The starting biochars and final catalysts were characterized to investigate their morphological, physical and chemical features through various techniques to elucidate activation treatment effects on the ultimate catalyst performance. The best catalyst Ni/RHCO2 presented good stability over 20 h of test and optimal selectivity values (>90 %), probably because of the better biochar features provided by CO2 activation such as porosity, crystallinity, and stronger Ni-biochar interactions.