Bench-scale study of electrochemically assisted catalytic CO2 hydrogenation to hydrocarbon fuels on Pt, Ni and Pd films deposited on YSZ

Abstract

Electrochemically assisted CO2 hydrogenation to fuels was studied at bench scale over different tubular (Pt, Ni or Pd)/YSZ electrochemical catalysts, under atmospheric pressure, at temperatures between 225 and 400 ºC and using high gas flow rates, gas compositions representative of CO2 capture exiting streams and changing H2/CO2 ratios (to simulate a discontinuous renewable H2 flow), as an approach towards its potential practical application.

Pt catalyst film was deposited from a precursor paste, while Ni and Pd films were deposited by a more easily scalable “electroless” technique. Both procedures resulted in relatively big metal particles which probably determined the comparatively high selectivity to methanol (up to 8 % at 400 ºC and H2/CO2=2), hydrocarbons (almost 100 % to C2H6 and C3H6) and dimethyl ether (up to 96 % at 300º C and H2/CO2=3) obtained for Pt, Ni and Pd, respectively, and the unusual small selectivity to CH4 and CO observed for Ni and Pd.

CO2 hydrogenation can be electrochemically enhanced for both positive and negative potentials by up to 3.2, 2.4 and 1.3 times for Pt, Ni and Pd, respectively, depending on the utilized operating conditions. Selectivity to the different fuels of industrial interest can be modulated by modifying applied potential.