CO2 utilization with a novel dual function material (DFM) for capture and catalytic conversion to synthetic natural gas: An update

Abstract

Dual function materials (DFMs) for CO2 capture and conversion couple the endothermic CO2 desorption step of a traditional adsorbent with the exothermic hydrogenation of CO2 over a catalyst in a unique way; a single reactor operating at an isothermal temperature (320°C) and pressure (1atm) can capture CO2 from flue gas, and release it as methane upon exposure to renewable hydrogen. This combined CO2 capture and utilization eliminates the energy intensive CO2 desorption step associated with conventional CO2 capture systems as well as avoiding the problem of transporting concentrated CO2 to another site for storage or utilization. Here DFMs containing Rh and dispersed CaO have been developed (>1% Rh 10% CaO/γ-Al2O3) which have improved performance compared to the 5% Ru 10% CaO/γ-Al2O3 DFM (0.50 g-mol CH4/kg DFM) developed previously. Ruthenium remains the catalyst of choice due to its lower price and excellent low temperature performance. The role of CO2 adsorption capacity on the final methanation capacity of the DFM has also been investigated by testing several new sorbents. Two novel DFM compositions are reported here (5% Ru 10% K2CO3/Al2O3 and 5% Ru 10% Na2CO3/Al2O3) both of which have much greater methanation capacities (0.91 and 1.05 g-mol CH4/kg DFM) compared to the previous 5% Ru 10% CaO/γ-Al2O3 DFM.