Beyond ideal selectivity: Systematic reactor and process design of RWGS membrane reactors for low-temperature CO2 conversion

The Reverse Water-Gas Shift (RWGS) reaction is a key step in CO 2 utilization pathways, but its performance is constrained by thermodynamic equilibrium. Integrating a water-vapor selective membrane in a packed-bed membrane reactor (PBMR) can enhance CO 2 conversion and enable operation at lower temperatures. To-date, the impact of the limited selectivity of such membranes on performance has not been studies. A dimensionless reactor model is developed to evaluate the effects of species perm-selectivity, sweep flow and operating conditions. The results show that high perm-selectivity for non-water species is not always beneficial, low perm-selectivity can outperform high perm-selectivity under some specific operating conditions. Non-monotonic trends, arising from the competing permeation of H 2 , CO, and CO 2 , underscore the importance of realistic membrane transport modeling. Integrated process loop to produce syngas incorporating a RWGS PBMR is studies. Among the four recycle and sweep configurations studied, the design with hydrogen sweep offers the best balance between conversion and energy efficiency, even with low membrane perm-selectivity. This configuration enables low-temperature conversion, potentially utilizing renewable heat supply, as opposed to a high-temperature traditional packed-bed reactor, highlighting the PBMR’s promise for intensified CO 2 conversion.