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In this paper, a concept of integrated CO2capture and reverse water–gas shift (ICCrWGS) process was proposed using NH3as the H2carrier. The CO2efficiency and total thermal energy consumption for the conventional rWGS, ICCrWGS using H2(H2-ICCrWGS) and NH3(NH3-ICCrWGS), were calculated. ICCrWGS using H2and NH3was conducted over the thermally stable Ni/CaZr dual-function materials (DFMs). NH3decomposition, CO2capture capacity, CO2conversion, and CO selectivity were addressed at different reaction temperatures, and the optimal temperature was determined to be 650 °C. The Ni/CaZr DFMs exhibited stable CO2capture capacity and CO productivity during ICCrWGS using the NH3carrier. A carbonate spillover mechanism for CO production over the Ni/CaZr DFMs in NH3-ICCrWGS was proposed using in situ diffuse reflectance infrared Fourier transform spectroscopy. It was found that CO is produced from the bridged bidentate carbonate route in the Ni–CaO interface.

An integrated CO2capture and direct methanation (ICCM) system has recently gained significant attention as a promising process to produce value-added chemicals. Compared to conventional CO2capture and utilization, ICCM is a simplified process that directly converts captured CO2without purification at lower thermal inputs. One of the primary limitations is the deactivation of the sorbent and the embedded catalysts after several thermal cycles. In this study, we formulated thermally stable macroporous structured Ni/CaO dual function materials (DFMs) by incorporating a Zr stabilizer. The textural properties, porosity, CO2capture performance, and catalytic activity of Zr-modified Ni/CaO (Ni/CaZr) were assessed. In situDRIFTS was used to investigate the possible intermediates and reactions during the ICCM. It was found that CH4is produced from the formate and methoxy intermediates route on the CaO surface and the CO intermediate route on the Ni surface. Ni/CaZr had improved thermal stability with the best CO2capture capacity (13–14 mmol of CO2/g), CH4productivity (13–14 mmol of CH4/g), CO2sorption, and desorption kinetics at 500 °C. The benefit of adding Zr for ICCM enhanced the macroporous structures, which enhanced the CO2mass transport and prevented the sintering of Ni and CaO.

The reversible coexsolution mechanism of perovskite oxides is emerging as an alternative method for synthesizing alloy catalyst nanoparticles. Co-exsolution is a partial decomposition process where multiple B cations diffuse from the bulk of a solid precursor and nucleate on the surface. The unique properties of exsolved alloy catalysts, including improved dispersion, thermal stability, and compositional malleability, make them particularly useful for converting CO2into chemical commodities and fuels. However, the coexsolution of alloys is still in development, and fundamental insights into the alloying mechanism, formation of nanoparticles, and defect chemistry are needed.