EFFECT OF TEMPERATURE ON ELECTROCHEMICAL REDUCTION OF HIGH-PRESSURE CO2 WITH IN, SN, AND PB ELECTRODES

Electrochemical reduction of high-pressure carbon dioxide with an indi um, a fin, and a lead electrode at a potential of -1.8 V versus Ag/AgC l saturated KCI was investigated in the range of 20-100 degrees C. Und er optimum experimental conditions, with the indium electrode, about 1 00% Faraday efficiency formic acid was selectively obtained at 20-60 d egrees C, and at 100 degrees C the formation efficiency was 44.5%. Wit h the tin electrode, 99.2% Faraday efficiency formic acid was obtained at 20 degrees C. With increasing temperature, the Faraday efficiency of formic acid decreased and that of hydrogen increased. In the case o f the lead electrode, Faraday efficiencies of formic acid and hydrogen were both about 50% at 20 degrees C. A maximum Faraday efficiency of formic acid (91.2%) was obtained at 60 degrees C. Hydrogen formation w as lowest at that temperature. For the electrodes, the formation of ca rbon monoxide was minimal at the temperatures tested.