Electrochemical reforming of ethanol in a membrane-less reactor configuration

Abstract

As a result of the research of a more integrated process for hydrogen production, a new concept of membrane-less electrochemical reformer rises up for single-step hydrogen production in a single chamber reactor. In this system, the solid polymeric electrolyte is replaced by a low concentration liquid KOH solution electrolyte, simplifying its scale up and enhancing the stability of the cell. The viability of the system is studied for electrochemical reforming of ethanol and under an alkaline environment, which avoids the use of Pt-Ru or Pt-Sn high metal loading electrodes. Instead of these catalysts, commercial Pd/C Vulcan and Pt/C black are sprayed over Carbon Paper to be used as anode and cathode catalysts, respectively. In all the experiments carried out, a hydrogen stream with 100% of faradaic efficiency has been obtained. A temperature of 85 °C, a 3.5 mm electrodes distance and a fuel feeding solution of 1 mol·L−1 EtOH and 4 mol·L−1 KOH are the optimised conditions found in the studied range. These optimised conditions lead to current densities above 450 mA·cm−2 at lower cell potentials (1.4 V) than required for water electrolysis leading to lower energy consumption values. It is a remarkable result, as this electrocatalytic activity is higher than that obtained in previous studies based on membrane electrode assemblies systems. Finally, the stability of the system has been verified by mild term electrocatalyic experiments coupled with Atomic Absorption Spectrophotometry and X-ray diffraction analysis of fresh and used electrodes.