Direct flue gas hydrogenation to methane over hydroxyapatite-supported nickel catalyst

Abstract

Low-carbon methane (CH4) obtained from captured CO2 is an interesting option for reducing greenhouse gas (GHG) emissions from carbon-intensive natural gas. Flue gases (FG) from power plants and industrial facilities are major CO2 sources, but their valorization still faces challenges associated with impurities (CO, O2, NOx, SO2) removal and carbon capture. In this work, we proposed the use of 20wt%Ni/hydroxyapatite (HAP) catalyst for the direct methanation of real FG without any prior purification on lab- and semi-pilot scales. The aim of this work is to validate the performance of direct flue gas methanation over HAP-based catalysts for the first time in literature, to the best of our knowledge. At 350 °C and 740 h−1, direct FG methanation on lab-scale yielded 76% and 89% conversions for CO2 and H2, respectively, for 50 h with 100% CH4 selectivity. On semi-pilot scale, stable 73% CO2 conversion and 100% CH4 selectivity were observed for 50 h. The results presented here validate the feasibility of the direct FG methanation without previous carbon capture and the potential of HAP as an alternative catalyst support for industrial catalysts for CO2 methanation.