摘要：Ceria- and urea-doped activated biochars were used as support for Ni-based catalysts for CO<sub>2</sub> methanation purposes. Different materials were prepared and tested to find the best catalytic formulation. After several CO<sub>2</sub> methanation experiments—carried out at 0.35–1.0 MPa and 300–500 °C—it was found that the most suitable catalyst was a wheat-straw-derived activated biochar loaded with 30 wt.% of CeO<sub>2</sub> and 20 wt.% of Ni. Using this catalyst, a CO<sub>2</sub> conversion of 65% with a CH<sub>4</sub> selectivity of 95% was reached at 1.0 MPa, 400 °C, and 13,200 h<sup>−1</sup>. From the study of the influence of the gas hourly space velocity, it was deduced that the most likely reaction mechanism was a reverse water–gas shift reaction, followed by CO hydrogenation. N-doping of the carbon support as an alternative to the use of ceria was also investigated. However, both CO<sub>2</sub> conversion and selectivity toward CH<sub>4</sub> values were clearly lower than those obtained for the ceria-containing catalyst cited above. The outcomes of this work indicate that a renewable biomass-derived support can be effectively employed in the catalytic conversion of CO<sub>2</sub> to methane.
