Electrochemical tubular fixed-bed reactor for conversion of pressurized CO2 to CO

Abstract

Electrochemical CO2 reduction reaction (CO2RR) can be used for activating the stable CO2 molecule to the more active CO for downstream purposes. Usually, this process is carried out in CO2-saturated aqueous solutions. The low solubility of CO2 in water of 0.033 M at 1 bar of CO2 and room temperature hinders both kinetics and mass transfer. In this study, a novel electrochemical tubular reactor for electrochemical CO2RR is proposed. The design was made with ease of scale-up in mind. A reactor can contain multiple electrochemical cells connected in series. Each cell consists of 3 main parts: porous anode, porous solid electrolyte, and porous cathode, all of which allow bulk flow of gas streams through the tubular reactor. Zn is the active electrocatalyst at the cathode for the conversion of CO2 to CO. Water is trickled through the cells to maintain electrolyte conductivity and also to sustain electrochemical reactions. The effects of CO2 pressure and flow rate and applied voltage on the CO2 conversion rate and yield are studied. About 1272 ppm of CO concentration and 19.61% of highest CO faradaic efficiency was obtained from a preliminary experiment conducted at 60 ml min-1, 7 V of CO2 at 10 bar.