Reverse water gas shift (RWGS) over Ni - Spatially-resolved measurements and simulations

The reverse water gas shift (RWGS) reaction is a method of converting waste CO2 and renewable H-2 to CO and H2O, where the resulting CO can be used in processes requiring syngas. This paper presents lab-scale data collected for RWGS on a Nickel catalyst coated monolith reactor, along with 3D modeling with ANSYS FLUENT and DUO (DETCHEM (TM) + OpenFOAM coupling) computational fluid dynamics software. Using a 42-step previously published mechanism, the software accurately predicts the outlet concentrations of H-2, H2O, CO and CO2 at two inlet flow rates. CH4 is underpredicted and the experimental data shows effectively complete conversion closer to the front-end of the catalyst than do the simulations. This may be due to inaccuracies in the measurement of the catalyst loading (F-cat/geo value), because if a higher F-cat/geo is assumed the simulation more closely matches the experimental results. Further, DUO and FLUENT results fit very well, and both codes are able to predict the general trend of significant species diffusion ahead of the monolith using the mixture averaged diffusion assumption. Ultimately, heat transfer with the monolith solid structure is inherently important, and thus isothermal calculations more closely match experimental values than do those with adiabatic boundary conditions. To better capture the thermal profile within the various channels it is necessary to model a 3D quarter monolith section.