Modulating the Evolution of Metastable CaO* for the Near-Theoretical Performance Breakthrough of Ni/CeO2-CaO in Integrated CO2 Capture and Methanation

Abstract

Integrated CO2 capture and utilization technology based on the calcium looping is burgeoning as an economical and viable strategy for achieving Carbon Neutrality. However, the drawback of easy sintering of CaO limits its potential to maximize CO2 capture and conversion. Here, a low-temperature hydrogen spillover decomposition strategy is proposed to synthesize high-performance CaO-based dual-functional material. This strategy significantly shortens the existence time of the transition state CaO*, enabling CaCO3 to be converted into CaO more rapidly. Compared with the traditional sol–gel method, the sintering of CaO is more effectively inhibited. Specifically, NiCa-400 achieves a CO2 capture of 17.8 mmol g−1 (theoretical value of 17.8 mmol g−1), a CH4 yield of 17.2 mmol g−1 (192% higher than the conventional method), and a CH4 selectivity of 97%. In addition, scale-up experimental studies further demonstrated its practical scalability. Guided by techno-economic analysis, coupling the proposed strategy with a coal-fired power plant can reduce energy consumption by 79% and save investment costs by 23% compared with a conventional carbon capture and utilization (CCU). This work bridges the gap between the actual and theoretical properties of traditional calcium-based dual-functional materials and provides a new solution for the high-value utilization of carbonates.