Novel electrochemical packed-bed reactor for carbon dioxide reduction

Abstract

Electrochemical reduction of carbon dioxide (CO2) is a promising strategy to recycle CO2 into valuable chemical products. Nevertheless, a conventional apparatus which usually utilizes stack design to maximize its surface-to-volume ratio requires many elements and complicated instruction assembly. The stack design often requires feed streams to flow in narrow channels throughout the cell, which is also constrained by membrane size roughly 1 m2 by current manufacture technology. This research focuses on development of a new type of electrochemical reactor that is suitable for industrial-scale applications. The novel electrochemical packed-bed reactor is designed for the electroreduction to covert CO2 into CO in the gas phase. Humidified CO2 was fed through the reactor, and a voltage was applied to the bed for initiate electrochemical reactions. The bed consists of 3 compartments including Zinc (Zn) deposited felt, ion-exchange resin, and platinized titanium arranged in this order. Effects of applied voltage and CO2 flow rates toward the CO2 reduction performance was investigated. The increasing of CO concentration and current were achieved with increasing voltage. The maximum CO concentation and the highest faradaic efficiency were observed at 6 V and 80 ml min-1 for a single-cell bed. The optimal condition for a two-cell bed was 11 V and 120 ml min-1. However, the effects of flow rate might oppose effects of mass transfer at high flow rate. An online infrared spectroscopy was coupled to the novel electrochemical packed-bed reactor for the CO product detection. The CO product analysis confirmed that the novel electrochemical packed-bed reactor successfully converts CO2 to CO.