Numerical and Experimental Investigations of Thermally Coupled Catalytic Hydrogen Combustion - Reverse Water Gas Shift Reactor for CO2 Conversion to Synthesis Gas

Abstract

From technological, societal, and political perspectives, the optimization of energy utilization, reduction of CO2 emissions, and mitigation of global environmental challenges have emerged as paramount concerns. In this study, a thermally coupled reactor that utilizes catalytic H2 combustion (CHC) as an energy source to drive reverse water gas shift (RWGS) was designed. The lab-scale reactor with a shell-and-tube configuration was experimentally tested utilizing the inner (tube) compartment for CHC over Ni/Al2O3 and outer (shell) compartment for RWGS over Mo2C/Al2O3. A maximum H2 conversion of 88% for CHC was achieved, while RWGS compartment achieved 58% CO2 conversion, with complete selectivity towards CO. The reactor was successfully operated for extended periods of time, with approximate 40 on/off cycles, totaling 400 h. It’s also analyzed numerically using a two-dimensional pseudo-homogeneous model. Both experimental and numerical results demonstrated the feasibility of the reactor concept and emphasized the importance of thermal management. Further investigations were conducted to examine the effects of reactor geometric parameters, specifically the length-to-diameter and diameter-to-diameter ratios, as well as operating conditions such as space velocities and feed temperatures, providing insights into the reactor's thermal behavior and the interplay between key parameters and reactor performance. Consequently, these findings serve as a basis for future design optimizations for enhanced efficiency and performance.