Large-scale conversion of bio-methanol into dimethyl ether: Performance analysis, multi-objective optimization, and a rigorous comparison between catalysts and process schemes

The development of advanced processes for the efficacious energy materials such as dimethyl ether (DME) from biomass-driven feedstocks is challenging. This feasibility study was aimed at achieving process intensification by optimizing the feed shift strategy for the methanol dehydration. The utilization of bio-methanol feed instead of the conventional stream was investigated in four systems configured with two processes (adiabatic and nonadiabatic) and two catalyst types (gamma-Al2O3 and ZSM-5). A rigorous mathematical model was developed, which was validated against real data from pilot- and plant-scale reactors. The optimum conditions were then determined using a multi-objective genetic algorithm. The feed temperature, flow rate, and composition significantly affected the DME yield. The optimization indicated that the non-adiabatic reactor with the ZSM-5 catalyst offered higher DME yields at lower temperatures and pressures. However, the system with the shell-and-tube type reactor requires a more complex design. The highest DME yield (39.55%) was obtained when the system operated at 529.4 K and 21.3 bar for a 10616.06 kmol/h bio-methanol feed with 90% of the alcoholic compound. These results can establish guidelines for the design of reactors to convert bio-methanol into DME. A future study on economic constraints would shed light on screening for the best strategy.