Electrochemical promotion for hydrogen production via ethanol steam reforming reaction

Abstract

In this work we have investigated for the first time the electrochemical activation of a catalyst for the ethanol reforming reaction. For that purpose, a Pt-KβAl2O3 electrochemical catalyst has been prepared, characterized and tested under ethanol reforming reaction conditions. The electrochemically supply of potassium ions under negative polarization step, strongly increased the hydrogen production rates leading to a reversible and controllable promotional effect. It has been attributed to the enhancement of the kinetic of ethanol dehydrogenation reaction, due to the strengthening of the chemisorptive bond of intermediate ethoxy molecules. It will increase the stability of this intermediate, thus favoring its formation, which initiates the ethanol reforming process. However, a large amount of carbonaceous species were formed on the catalyst surface during the negative polarization step that causes a continuous decrease in the catalytic activity under long polarization times. Under these conditions, the application of a catalyst potential of 2 V leads to a complete removal of the previous deposited carbonaceous molecules which allows further electrochemical activation steps. The obtained catalytic results have been supported by in-situ temperature programmed oxidation analysis and ex-situ Raman spectroscopy and Scanning Electron Microscopy. These techniques, in conjunction with the obtained catalytic results, have demonstrated the interest of the EPOC phenomenon for in-situ tuning the adsorption of reactants molecules on catalyst surface and its application in the hydrogen production technology, improving catalyst conversion and selectivity.