Synthesis of Bio-Dimethyl Ether Based on Carbon Dioxide-Enhanced Gasification of Biomass: Process Simulation Using Aspen Plus

Process simulation for a single-step synthesis of dimethyl ether (DME) based on the CO₂-enhanced gasification of rice straw was conducted using Aspen Plus. The process consists of a gasification unit, a heat recovery unit, a gas purification unit, a single-step DME synthesis unit, and a DME separation unit. In the simulation, highly pure DME was produced by the control of CO₂ concentration in syngas to a very low level prior to synthesis. A gasification system efficiency of 36.7% and CO₂ emission of 1.31kgkg_DME^-1 were achieved. This bio-DME production based on the CO₂-enhanced gasification of biomass was cost-effective as it required 19.6% less biomass than that of DME production based on conventional biomass gasification. The performance and environmental benefits of the proposed process could be further improved by the utilization of unreacted gases and the managing of CO₂ generated by the incorporation of a polygeneration concept or carbon storage.