Harnessing\nAmmonia as a Hydrogen Carrier for Integrated\nCO<sub>2</sub> Capture and Reverse Water–Gas Shift

In\nthis paper, a concept of integrated CO<sub>2</sub> capture and\nreverse water–gas shift (ICCrWGS) process was proposed using\nNH<sub>3</sub> as the H<sub>2</sub> carrier. The CO<sub>2</sub> efficiency\nand total thermal energy consumption for the conventional rWGS, ICCrWGS\nusing H<sub>2</sub> (H<sub>2</sub>-ICCrWGS) and NH<sub>3</sub> (NH<sub>3</sub>-ICCrWGS), were calculated. ICCrWGS using H<sub>2</sub> and\nNH<sub>3</sub> was conducted over the thermally stable Ni/CaZr dual-function\nmaterials (DFMs). NH<sub>3</sub> decomposition, CO<sub>2</sub> capture\ncapacity, CO<sub>2</sub> conversion, and CO selectivity were addressed\nat different reaction temperatures, and the optimal temperature was\ndetermined to be 650 °C. The Ni/CaZr DFMs exhibited stable CO<sub>2</sub> capture capacity and CO productivity during ICCrWGS using\nthe NH<sub>3</sub> carrier. A carbonate spillover mechanism for CO\nproduction over the Ni/CaZr DFMs in NH<sub>3</sub>-ICCrWGS was proposed\nusing in situ diffuse reflectance infrared Fourier transform spectroscopy.\nIt was found that CO is produced from the bridged bidentate carbonate\nroute in the Ni–CaO interface.