CO2 capture and electro-conversion into valuable organic products: A batch and continuous study

Abstract

CO2 gas is present in trace amount in the environment, but it is one of the major causes of global warming. It is necessary to reduce the CO2 concentration as it is increasing day by day due to excessive use of fossil fuels. This paper consists of the electrochemical process for CO2 reduction. Batch and multi-compartment continuous reactors were fabricated for CO2 capture and electro-reduction by using KOH as an electrolyte as well as a sorbent to obtain organic products such as formic acid, methane, and methanol. In the batch study, stainless steel cathode was tested while for continuous study two different Cu based cathodes were analyzed (Cu plates and Cu based electro-catalyst deposited on stainless steel plates). In all the electrolysis processes, stainless steel was used as the anode. Cost effective polyvinyl alcohol chemical hydrogel (PCH) was used as electrode binder. Electro-catalyst was prepared by co-precipitation method. Our study consists of optimization of key variables such as voltage, electrolysis time, electrolyte concentration and faradaic efficiency. For the batch study, formic acid was observed as main product with the faradaic efficiency (FE) of 41.18% at optimized parameters. For the continuous reactor, methanol and methane were the main products with the faradaic efficiency of 20.1% and 16.15% respectively for Cu plate cathodes whereas 36% and 10.29% respectively for electro-catalyst based cathodes.