(626b) Thermally Coupled Catalytic Hydrogen Combustion-Reverse Water Gas Shift Reactor: Model-Based Feasibility Study, Parametric Analysis, and Experimental Proof-of-Concept

Thermally coupled catalytic hydrogen combustion-reverse water gas shift reactor for CO₂ conversion to synthesis gas was designed and numerically analyzed using a 2D model with a shell-and-tube configuration. A transient, pseudo-homogeneous mathematical model was formulated accounting for axial and radial heat dispersion and using experimentally obtained reaction kinetic parameters. Transient reactor behavior was studied to analyze the dynamic behaviour. Steady-state reactor performance was analyzed in terms of temperature and reactant/product distribution, as well as output parameters of practical importance, namely maximum and outlet reactor temperatures, and outlet conversions. Numerical simulations demonstrate the feasibility of the suggested reactor concept and providing insights into thermal management, including the formation of hot spots, appearance of temperature fronts, and the importance of thermal insulation. The model predicted the possibility of 100% catalytic H₂ combustion conversion and 80% CO₂ conversion, with the reactor temperature of ca. 900 °C.

In the follow-up experimental study, a lab-scale reactor with a shell-and-tube configuration was experimentally tested utilizing the inner (tube) compartment for H₂ oxidation (HO) over Ni/Al₂O₃ and outer (shell) compartment for reverse water gas shift (RWGS) over Mo₂C/Al₂O₃. After ignition, an evident rise in reactor temperature was observed, which was accompanied by a stable HO conversion. The transfer of heat from the HO (exothermic) compartment to the RWGS (exothermic) compartment was evidenced by a reduction in temperature within the HO compartment. A maximum H₂ conversion of 88% for HO was achieved, while RWGS compartment achieved 58% CO₂ conversion, with complete selectivity towards CO. The reactor demonstrated a continuous, stable operation for a duration of 60 h, with 42% CO₂ conversion and complete selectivity to CO.