(181e) One-Step Dimethyl Ether Synthesis from Carbon Monoxide-Rich Syngas in a Slurry Reactor

Recently, DME (dimethyl ether) has received growing attention due to its potential as an alternative clean fuel and a chemical feedstock. One-step DME synthesis from syngas has many economic and technical advantages over conventional two-step synthesis. In the present study, one-step DME synthesis from CO-rich syngas over the bifunctional catalyst comprising a methanol synthesis catalyst (Cu/ZnO/Al2O3) and a solid acid catalyst (γ-Al2O3) was investigated. Considering the highly exothermic characteristics of DME synthesis, liquid-phase DME synthesis was carried out in a slurry reactor that provides good mixing and efficient heat control. The influence of various reaction parameters such as reaction temperature (230-280 oC), reaction pressure (3.0-7.0 MPa), GHSV (800-6000 ml/g-cat/hr), and content of γ-Al2O3 on CO conversion and DME space time yield (STY) was closely examined at a H2:CO ratio of 0.5 that is very close to coal-derived syngas. The effect of H2:CO ratios (0.5-3.0) on DME synthesis was also investigated. Reaction temperature and pressure showed similar positive effect on DME synthesis. Lower GHSV caused higher CO conversion, but lower DME STY. The excessive content of γ-Al2O3 had an adverse effect on both CO conversion and DME STY. Among various H2:CO ratios, the maximum DME space time yield (13.5 mol/kg-cat/hr) was observed at a H2:CO ratio of 1.0. The results obtained in this study can be used as basic data for design and operation of a fluidized bed DME synthesis reactor.