One-Step DME Synthesis from Coal-Derived, CO-Rich Syngas in a Slurry Reactor

Abstract

This study investigates one-step dimethyl ether (DME) synthesis from coal-derived, CO-rich syngas over a bifunctional catalyst comprising a methanol synthesis catalyst (Cu/ZnO/Al₂O₃) and a methanol dehydration catalyst (γ-Al₂O₃). The liquid-phase DME synthesis was carried out in a slurry reactor that provided good mixing and excellent heat removal. Higher CO conversion and DME space time yield (STY) were observed at a higher reaction temperature and a higher pressure. A lower gas hourly space velocity (GHSV) caused higher CO conversion, but a lower DME STY. Excessive content of γ-Al₂O₃ had an adverse effect on both CO conversion and DME STY. Among various H₂:CO ratios, the maximum DME STY (13.5 mol/kg-cat/h) was observed at a H₂:CO ratio of 1.0. CO₂ in the feed syngas had a negative effect on DME synthesis. The results and data obtained in this study can be used as basic data for the design and operation of a large scale bubble column reactor and for further application to a three-phase fluidized bed reactor.