Porous hollow Ni/CaO dual functional materials for integrated CO2 capture and methanation

Abstract

Excessive CO₂ emissions present significant environmental and energy challenges, driving the need for effective strategies to reduce CO₂. Integrated CO₂ capture and utilization (ICCU) processes have drawn considerable attention by combing carbon capture and catalytic conversion in a unified process. The rational design of efficient dual-functional materials (DFMs) is key to achieving high-efficiency ICCU processes. Here, we synthesized a series of CaO-based DFMs with varying Ni loadings, in which the porous hollow CaO prepared by a sacrificial template method was employed as the adsorbent. The porous hollow structure are effectively to improve the diffusion of CO₂ species and provide sufficient space for volume expansion after CO₂ capture. The optimized conditions for adsorption and catalytic sites were determined to be at 550 °C with 5wt% Ni loading. Under these conditions, the adsorption capacity of 5 %Ni/CaO-P reached 7.02 mmol·g⁻¹ _DFM, with a CH₄ yield of 2.85 mmol·g⁻¹ _DFM and a CH₄ selectivity of 94.09 %. After 19 cycles, the adsorption capacity of 5 %Ni/CaO-P is maintained at 4.50 mmol·g⁻¹ _DFM with a CH₄ yield remaining stable at 0.50 mmol·g⁻¹ _DFM due to the slight sintering of Ni species. Integrated CO₂ capture and methanation offer a pathway for carbon recycling, emissions reduction, and sustainable development.