Thermally double coupled reactor coupling aqueous phase glycerol reforming and methanol synthesis

Abstract

This study proposes a novel thermally double coupled reactor (TDCR) coupling endothermic aqueous phase glycerol reforming (APGR) with exothermic methanol synthesis (MS), utilizing heat transfer between both channels. Hydrogen (H2) source and availability are known as barriers to carbon dioxide conversion to methanol via MS reaction. Waste glycerol could be a source of H2 through APGR reaction. The steady state TDCR model consists of two concentric channels: 1) an inner tube to which CO₂ and H₂ are fed as reactants for exothermic MS and 2) an outer annulus channel through which glycerol and steam are supplied for endothermic APGR. The TDCR could operate without external heat supply when two reactions were coupled. A computational fluid dynamic (CFD) model was established to study this TDCR. APGR was assumed to be catalyzed by Pt/Al₂O₃ at 200−250 °C and 20−25 bar. MS was modeled with a Cu/ZnO/Al2O3 catalyst at 200−250 °C and 50−80 bar. Heat transfer from the exothermic channel to the endothermic channel helped increase glycerol conversion while methanol productivity is the same as conventional reactor. Cocurrent and countercurrent feed configurations were compared and it was found that the cocurrent configuration offered more uniform temperature distribution in the channel with a larger temperature difference between the two channels. On the other hand, hot spots and cold spots were observed in the countercurrent configuration. Effects of operating conditions of both channels: H2:CO2 and glycerol:steam ratios, inlet temperature, pressure, and total feed flow rate on reactor performance significantly affected the performance of TDCR.