Highly stable FeNiMnCaO catalyst for integrated CO2 capture and hydrogenation to CO

The integrated CO2 capture from flue gas and hydrogenation can be realized by the consecutive calcium-looping (CaL) and reverse-water–gas-shift (RWGS) reactions. However, the incompatibility between the catalysis and adsorption components aggravates the sintering and deactivation of metal particles and CaO base material during the high-temperature process. Herein, we prepared a highly efficient and stable FeNiMnCaO material via a modified sol–gel method for in situ CaL and RWGS reaction, exhibiting a CO2 adsorption capacity of 13.2 mmol g−1 at 40 cycles with 58.0 % CO2 conversion and 100 % CO selectivity at 700 °C. The highly-dispersed Fe and Ni species in the developed catalyst not only suppressed the sintering of MnCaO, but also synergistically benefited the RWGS reaction, where FeOx species promoted CO2 adsorption and metallic Ni facilitated H2 dissociation. The reaction followed the H-assisted association formate mechanism, in which adsorption of CO2 occurred at the FeOx-CaO interface with the aid of the hydroxyl surface groups to form bidentate bicarbonates, followed by dehydration to bidentate formate and decomposition to CO and H2O in the presence of Ni-dissociated reactive H* species.