CO2 reduction and formic acid production in the developed double-layer cathode electrochemical reactor

Abstract

This study investigated the reduction of CO2 and its conversion into formic acid in a developed double-electrode layer trickle bed electrochemical reactor (TBER) to combat global warming. VulcanXC72 carbon black and polytetrafluoroethylene (C-PTFE) mixture was pasted on stainless steel mesh to form the cathode layers which was characterized using SEM,BET,FTIR, porosity and particles size distribution. Using K2CO3 alkaline solution, CO2 was in situ reduced over the cathode bed suggesting a renewable energy source to replace hydrocarbon fuel. The anode’s plates reduces the reactor voltage and improve the current distribution. The effect of cell voltages, gas and liquid flow rates, K2CO3 concentrations, and temperatures were systematically studied and formic acid production was predicted as well. CO2 was successfully reduced in this system and reached its maximum conversion at 94.47% in 40 min at a reduction temperature of 10 °C which is attributed to the enhancement of CO2 solubility in the electrolyte at low temperatures. At the best conditions, formic acid production increased with time and reached 266 ppm after 60 min, presenting this process as an alternative to the traditional methods. The development of a two-layer reactor working in trickling flow mode is used for the first time in such highly complex processes, where each layer acts as a separate reactor from the other layer. Moreover, to avoid using expensive metals as electrocatalysts and make the process eco-friendly, a conductive carbon black was used as an electrocatalyst. Despite this promising results, the system was designed to be scalable for industrial use and used in wastewater treatment and methane, methanol, and ammonia production.