Conversion of carbon dioxide to methanol through the reduction of formic acid on chromium

Abstract

BACKGROUND Formic acid (FA) can be produced from CO2 by high rate and high percentage current efficiency (%CE) which exceeds 90% on some metals. This work aims at the electrochemical conversion of formic acid to methanol (MeOH) by a two- step process including the conversion of CO2 to formic acid in the first and the reduction of formic acid to MeOH in the second. RESULTS The main products of the electrochemical reduction of FA in 85% H3PO4, at 80°C on chromium were methyl formate (HCOOMe), MeOH and CH4. The rate of the reduction increased both by increasing the negative potential and the concentration of FA. The total %CE in all experiments exceeded 100% and this was attributed to the cathodic dissolution of chromium which provided an additional reduction capacity. The selectivity to MeOH and HCOOMe was between 89 and 98% and the highest current density was 13 mA cm−2, at –0.95 V. CONCLUSIONS FA is selectively reduced to MeOH and its secondary product HCOOMe on a Cr cathode. The experimental results showed that chromium is the most efficient cathode for the reduction of FA. © 2016 Society of Chemical Industry