High stability for the integrated CO2 capture and methanation reaction over the MgO-modified Ni-CaO bifunctional catalyst

Abstract

Integrated CO₂ capture and conversion into CH₄ via in-situ methanation reaction (ICCU-methanation) provides an effective pathway for large-scale mitigation of anthropogenic carbon dioxide emissions. Keystone for the successful ICCU- methanation is the development of stable bifunctional catalysts to handle the sintering of metal particles and structural deterioration in a long-duration cyclic operation. Herein, we prepared a highly stable MgO-modified Ni-CaO bifunctional catalyst, maintaining 100% CO₂ conversion and 95.0% CH₄ selectivity throughout the entire 50 cycles. More importantly, the CO₂ sorption capacity loss of the optimal 10MgO-5Ni-CaO is only 22.5%. This excellent stability is attributed to the presence of MgO as a spacer that separates CaO particles to suppress their aggregation, thereby ensuring the structural stability of the catalyst. In addition, the formed Ni-Mg-O solid solution limits the migration and sintering of Ni particles, thereby effectively stabilizing Ni particles and guaranteeing their high methanation activity.