Modeling and Optimization of Mass and Heat Flux Profiles in a Multifunctional Reactor for CO₂ and H₂ Valorization to Dimethyl Ether

Abstract

Dimethyl ether is one of the future synthetic fuels in the 2025–2050 energy mix. This work presents a detailed numerical optimization approach for a multifunctional reactor for the direct synthesis of dimethyl ether from CO2 and H2, with a specific focus on the methodological aspect that can be used as a guide to help or evaluate the development of innovative technological strategies. An innovative approach based on the dynamic optimization of the mass and heat flux profiles is applied for the intensified configuration, coupling simultaneously the reaction, heat exchange, and membrane separation (R–E–M). Several degrees of freedom and optimization strategies (mono- and multi-objective/deterministic and stochastic) are addressed. The energetic criterion is evaluated, namely, the total heat power exchanged. Optimization results highlight the performance improvement potentialities offered through the optimal exploitation of the synergy between these elementary functions. Simulation results show that the kinetic inhibition caused by water can be overcome and that a water-free process output is achievable, enabling an economic gain due the removal of a postreaction separation (water/methanol). The heat flux optimization provides more flexibility for mass transfer. Up to 95 and 98% in DME yield and CO2 conversion have been obtained per single pass for optimal theoretical heat- and mass-transfer flux profiles, respectively, within a multifunctional reactor. The results are obtained for the reactor inlet temperature and pressure of 518.15 K and 70 bar, respectively.