Optimal design of intensified processes for DME synthesis

Dimethyl ether (DME) is widely used as green aerosol propellant, precursor to other organic compounds, or as a clean fuel for diesel engines or in combustion cells. The classic method for producing DME is by dehydration of methanol in a catalytic gas-phase reactor, and purification in a direct sequence of two distillation columns. Reactive distillation (RD) is a much better alternative for DME synthesis, based on process intensification principles. This paper presents the optimal design of novel DME processes based on reactive distillation, and makes a fair comparison with the classic reactor-separation-recycle process (for a plant capacity of 100 ktpy DME). The new RD processes were optimized in terms of minimizing the total annual costs, leading to savings of 30% in CapEx and 6% in energy requirements for the RD process. The results indicate that a RD column is recommended for new DME plants, while a combination of gas-phase reactor and RD is suitable for revamping existing plants.