Strategies for improving CO2 utilization in microchannel enabled production of dimethyl ether

Intensified production of dimethyl ether (DME) from CO2-containing syngas is modeled in a microreactor involving porous layers of Cu-ZnO/Al2O3 and y-Al2O3 catalysts washcoated to the opposing faces of the reaction channels neighbored by physically segregated cooling channels. Steady-state reactive transport of syngas within catalyst layers and conservation of momentum, heat and mass are coupled with in-situ counter-current air cooling in two spatial dimensions in the context of a mathematical model that can closely predict the literature-based experimental data. Simulations run at inlet temperature, pressure, molar H-2/CO and H-2/CO2 ranges of 493-508 K, 20-60 bar, 2.5-4 and 5-12, respectively, commonly point out a fast rise in temperature, mostly due to CO hydrogenation, followed by its monotonic decline. Negative CO2 conversions from methanol-to-CO2 route driven thermodynamically by the methanol produced by the faster CO hydrogenation can be prevented, and CO2 conversions up to similar to 10% can be obtained by dosing syngas below 498 K or by enriching syngas with CO2 to keep H-2/CO2 < 7.5. These measures, however, reduce both CO conversion and DME yield. Distance between Cu-ZnO/Al2O3 and y-Al2O3 layers has negligible effect on temperature distribution.