potassium hydrogencarbonate in water byproducts: C2H6, C3H6, C3H8; Electrochem. Process; potentiostatic electrochemical reduction of CO2 at a Cu electrode (-1.35 to -1.75 V) in KHCO3 aq. soln. at 298 K (pCO2 = 104.4-107.4 kPa), further products; gas chromy., HPLC;