Phosphate assisted integrated carbon dioxide capture and conversion to methane

Abstract

Phosphate salts have been previously studied as carbon dioxide capture reagents. However, the direct conversion of the captured carbon dioxide species to hydrogenated products is not well studied with phosphate-assisted systems. Herein, we report the conversion of captured carbon dioxide to methane in such a system. When a nickel-based catalyst was used, the reactivity was strongly inhibited due to unwanted interaction of nickel with the phosphate species present in the system. However, with 5% Ru/Al₂O₃ as the catalyst, 100% conversion of captured CO₂ to methane was achieved after 6 hours under 50 bar H₂ at 200 °C. 5% Ru/Al₂O₃ was also able to maintain its reactivity over several capture/hydrogenation cycles.