Developing CO2-to-DME tandem kinetic model: Integrating methanol and DME synthesis under a unified framework

Dimethyl ether (DME), a chemical of significant demand within the process industry, can be produced from CO 2 via tandem reactions in which methanol acts as an intermediate. While various catalyst combinations have been the subject of experimental study, kinetic models for this tandem reaction system remain underexplored. In the conventional approach to developing a kinetic model of the CO 2 -to-DME tandem reaction system, the kinetic models developed for single catalysts of the methanol and DME synthesis are integrated without consideration of the effect of the reaction environment on the separate reactions and the respective catalysts. This work proposes a pragmatic approach to the development of a kinetic model for the CO 2 -to-DME tandem reaction system. Firstly, separated synthesis of methanol and DME are conducted on CuO/ZnO/Al 2 O 3 and KZSM-5 catalyst, respectively. The existing single-catalyst kinetic models are validated using the experimental data. Secondly, the influence of the environment of the tandem reaction on the respective catalysts is examined. CO 2 exerts an inhibitory effect on the DME synthesis catalyst. Subsequently, CO 2 inhibition effect is incorporated into the single-catalyst DME kinetic model. This is then integrated with the single-catalyst methanol kinetic model to develop the extended tandem kinetic model. The incorporation of a CO 2 inhibition term results in a substantial enhancement of the prediction performance of the tandem kinetic model. Finally, the three reactions-coupling-related parameters of extended tandem kinetic model are re-estimated using tandem experimental data. The obtained extended tandem kinetic model demonstrates a high degree of prediction accuracy for the tandem experimental results.