Integrating calcium-looping and reverse-water–gas-shift reaction for CO2 capture and conversion: Screening of optimum catalyst

Abstract

Integrating calcium-looping cycle (CaL) with reverse-water–gas-shift (RWGS) reaction represents an effective path to realizing integrated CO2 capture and utilization (ICCU). Screening a suitable catalyst to construct highly efficient CaO-based dual function materials (DFMs) is essential for CaL-RWGS. In the current work, M@CaO (M = Ni, Co, Mn, and Fe) DFMs are prepared for CaL-RWGS, and the influence of catalyst component on the structure, CO2 capture and RWGS performance, and kinetic behaviors of the CaO-based DFMs is investigated. Results show that the interaction between CaO and catalyst affects the average grain size and dispersion of metallic catalyst, oxygen vacancy concentration, surface basicity, and reducibility of CaO-based DFMs. The desired Mn@CaO DFMs exhibit outstanding CaL-RWGS performance at 650 °C, 15%CO2 and 50%H2, with a great CO2 uptake (12.30 mmol CO2/g), a favorable CO yield (5.92 mmol CO/g), and an impressive CO2 conversion (53.53%), as well as a high CO selectivity (89.98%). Furthermore, Mn@CaO exhibits excellent carbonation and regeneration kinetics but inferior working stability for CO2 capture and CO production in multiple CaL-RWGS cycles. Overall, Mn could be a competitive and cost-effective catalyst candidate for high-performance CaO-based DFMs for CaL-RWGS applications, while further work is needed to improve cyclic stability.