Sorption enhanced dimethyl ether synthesis under industrially relevant conditions: experimental validation of pressure swing regeneration

Abstract

Dimethyl ether (DME) is one of the most attractive alternative fuel solutions under consideration worldwide. However, its production from CO₂-rich feedstock or CO₂ directly is limited via conventional processes and therefore considered unattractive. For CO₂ utilisation, the production and efficient handling of steam remains a major bottleneck. Sorption enhanced DME synthesis (SEDMES), which combines heterogeneous catalysis with in situ water adsorption, is a promising process intensification strategy for the direct production of DME from CO₂. In this work, SEDMES is demonstrated experimentally on a bench-scale reactor with pressure swing regeneration under industrially relevant conditions. Pressure swing regeneration, rather than the time and energy intensive temperature swing regeneration, shows high performance with over 80% single-pass carbon selectivity to DME. This already allows for a factor four increase in productivity, with further optimisation still possible. With the proposed Sips working isotherm for the water adsorbent, and the methanol synthesis and dehydration kinetics, the validated dynamic cycle model adequately describes the SEDMES bench-scale data. Applying shorter cycle times, made possible by pressure swing regeneration, allows optimisation of the DME productivity while maintaining the high single-pass yield typical for SEDMES. The experimental confirmation shown in this paper unlocks the full potential of the high efficiency carbon and hydrogen utilisation by SEDMES technology.