Hydrodynamic effects on the direct conversion of syngas to methyl acetate in a two-stage fixed-bed/fluidized-bed combined reactor

Abstract

The direct conversion of syngas to methyl acetate (MA) via dimethyl ether (DME) was carried out in a combined fixed/fluidized bed reactor. Two catalysts were used in this study: Cu-ZnO-Al2O3 (CZA) and spray-dried ferrierite zeolite (SPD-FER). DME was synthesized with syngas to DME under CZA and SPD-FER, while DME carbonylation - i.e., that of DME to MA - proceeded with SPD-FER. DME synthesis was conducted in a fixed bed located at the bottom whereas DME carbonylation was conducted in a fluidized bed located at the top. As the space velocity increased, the XCO decreased, since the flow regime changed from particulate regime to bubbling regime, thus affecting attrition and the increase in the deactivation rate. Since the synthesis of DME from the syngas reaction is a mole reduced reaction, the regime transition occurred at a greater than predicted space velocity. When the molar fraction of CO increased, the XCO decreased whereas the XDME increased by approximately 50 %. Compared to the combined fixed/fixed bed results, the XCO and XDME both increased in the combined fixed/fluidized bed reactor. Lastly, the deactivation rate was higher in the combined fixed/fluidized bed than it was in the fixed/fixed bed.