Intensification of Direct CO2-to-Dimethyl Ether Conversion in Sorption-Enhanced Reactors: A Multiscale Analysis

Abstract

The transition to a circular carbon economy requires the valorization of carbon dioxide (CO₂) into high-density energy carriers such as dimethyl ether (DME). Traditional production methods are constrained by thermodynamic equilibrium and by the inhibitory effect of H₂O produced during CO₂ hydrogenation. This review presents a multiscale evaluation of sorption-enhanced DME synthesis, a process intensification technique that employs in situ H₂O removal to circumvent these limits. At the pellet scale, the critical balance between metallic copper dispersion and Brønsted acidity in the dehydration reactions is discussed, and Zeolite 3 A, as a benchmark H₂O-selective adsorbent, is assessed. The effects of operating conditions, namely temperature, pressure, and space velocity, on defining operating windows to balance kinetic and thermodynamic phenomena are presented. At the reactor scale, advanced spatial architectures, including hybrid and core-shell pellets, as well as multi-column pressure-swing adsorption cycles, are considered. Finally, system-level analysis assesses the green premium of e-DME, identifying renewable H₂ costs as the primary economic barrier, and validates the technology’s compliance with the 70% greenhouse gas reduction thresholds mandated by the European Renewable Energy Directive (RED II). The review concludes with a strategic outlook that calls for the development of water-agnostic catalytic sites, multivariate digital-twin optimization, and non-uniform axial-bed engineering to bridge the remaining gaps toward 2050 industrial deployment.