Harnessing Ammonia as a Hydrogen Carrier for Integrated CO2 Capture and Reverse Water-Gas Shift.

Abstract

In this paper, a concept of integrated CO2 capture and reverse water-gas shift (ICCrWGS) process was proposed using NH3 as the H2 carrier. The CO2 efficiency and total thermal energy consumption for the conventional rWGS, ICCrWGS using H2 (H2-ICCrWGS) and NH3 (NH3-ICCrWGS), were calculated. ICCrWGS using H2 and NH3 was conducted over the thermally stable Ni/CaZr dual-function materials (DFMs). NH3 decomposition, CO2 capture capacity, CO2 conversion, 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 CO2 capture capacity and CO productivity during ICCrWGS using the NH3 carrier. 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.