Harnessing Ammonia as a Hydrogen Carrier for Integrated CO2Capture and Reverse Water–Gas Shift

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.