Valorization of CO2 to DME using a membrane reactor: A theoretical comparative assessment from the equipment to flowsheet level


Carbon utilization plays a pivotal role in the circular carbon economy approach. However, CO2 conversion technologies, including thermocatalytic hydrogenation approaches, entail several challenges such as thermodynamic limits and low kinetic rates. In the pursuit of eliminating these two hurdles, this study aims to highlight the unique synergy and high potential of the combination of two emerging technologies: catalytic zeolite membrane reactor and direct dimethyl ether synthesis over hybrid catalysts of Cu/ZnO/Al2O3/HZSM-5. To this end, an equation-based pseudo homogenous model for a plug flow membrane reactor, previously developed in Aspen Custom Modeler, will be verified using experimental data in the literature and then coupled with the appropriately selected kinetic models, which describe this particular reaction system accurately. This enables us to confidently identify the impact of several membrane reactor's characteristics and process parameters on the conversion and selectivity. We also analyze a membrane-reactor-based dimethyl ether synthesis process and compare it with the conventional counterpart. According to our results, at 7.5 MPa pressure, a membrane-based process design offers 1.5%, 44.5% and 69.4% savings in power, heating and refrigerant utilities, respectively. These reductions correspond to 7.3% improvement in CO2 utilization efficiency as a metric to compare the environmental performance of emerging green fuel/chemicals.
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