(Invited) Elevated Temperature CO2 Adsorption Separation and Electrochemical Conversion：Reaction Mechanism and Technology Development

Abstract

Coal gasification is a clean way to utilize coal. Carbon dioxide is a significant emission in coal chemical plants. Before the fuel gas produced from coal chemical plants is utilized, CO2 mixed in the fuel gas has to be separated. A technical route combining elevated temperature CO2 adsorption separation, high temperature CO2 electrolysis and curtailed renewable energy can achieve high-efficiency carbon dioxide separation and utilization in a coal chemical plant. Elevated temperature CO2 adsorption separation (250-350oC) greatly match the temperature of the produced gas from coal chemical plants and thereby purifies the fuel gas in an efficient way. Further, high temperature CO2 electrolysis by solid oxide electrolysis cell (SOEC, operated at 600-1000oC) can fully utilize the curtailed renewable energy, like solar power, wind power and hydropower, to convert CO2/H2O into syngas again. In this study, the effort on these two key technologies, the elevated temperature CO2 adsorption separation and CO2 electrolysis by SOEC, were focused from the perspective of micro scale to macro scale. In the micro scale, the heterogeneous reaction mechanism of CO2 adsorption and electrolysis at an elevated temperature was discussed. In the unit level, the reactor was developed coupling the reaction mechanism and multi-physics (including fluid flow, diffusion, heat transfer and charge transfer). Facing with unstable renewable energy, the dynamic behavior of CO2 electrolysis become a new study focus. In the macro scale, system integration and technology development in the future were analyzed. This technical route is a potential way to simultaneously relieve such a great amount of renewable energy curtailment and carbon dioxide emission.