The influence of cell design and electrolysis parameters on the cathodic coupling of butadiene and carbon dioxide in acetonitrile. I. Undivided parallel plate configurations

Abstract

The reduction of carbon dioxide in the presence of excess butadiene in acetonitrile leads to a mixture of carboxylic acids, pentenoic acids (two isomers), hexenedioic acids (two isomers) and decadienedioic acids (three isomers). The total current yield can exceed 60%. The current efficiency and the ratio of products are functions of both cell design and other electrolysis parameters. This paper reports studies of this coupling reaction in several undivided flow cells, where cyclindrical cathodes (lead-plated nickel gauze, reticulated carbon of various porosity, carbon felt) were surrounded by a platinum gauze anode. The electrolyte was ditetraethylammonium oxalate and/or tetraethyl-ammonium formate so that the counter electrode reaction was the oxidation of the anions to CO₂ or CO₂+H⁺, respectively. This choice avoids solvent decomposition or other unwanted reactions at the anode, and may be helpful to the cathode chemistry by replenishing the cathode active species, CO₂, and possibly also creating a controlled supply of protons to the cathode.