Development, testing, performance analysis and modelling of a biochar-based catalyst for methanation reaction

Hydrogenation of CO2 to produce synthetic methane is a promising alternative to reduce the dependence on fossil fuels of high-temperature industrial processes hard to be electrified, contributing to mitigation of global warming. To reach enough conversion ratios and reasonable reactor sizes, the Sabatier reaction is usually performed via heterogeneous catalysis. Metallic catalysts, as nickel or ruthenium, are the most used supported over mesoporous alumina. The present work proposes and fully investigates for the first time the use of olive kernel biochar obtained from pyrolysis as support of methanation catalyst. The so-obtained biochar, with 530 m2/g specific surface area, is evaluated as a cost-effective and sustainable support. A Ni-based (10 wt%) catalyst was synthesized and tested in a fixed-bed methanation pilot plant. The obtained conversion ratios for gas hourly space velocity of 6000 h−1 were above 60 % for stoichiometric ratio and atmospheric pressure. A kinetic model was developed and validated with experimental measurements, finding discrepancies below 10 % between predictions and experiments. Even though the H2-TPR analyses revealed incomplete nickel reduction during the activation stage, the preliminary results are very promising as the achieved performance figures are similar, even higher, than that obtained in pressurized facilities and/or using Ni-Ce catalysts.