Hydrogen Production from Ethanol Using a Plasma Reactor with an Alumite Catalyst Electrode

Abstract

With the aim of developing a non-equilibrium reactor for proton exchange membrane fuel cell (PEMFC) systems and other applications, hydrogen was produced from ethanol using a non-equilibrium plasma reactor combined with a catalyst, which consisted of an alumite catalyst electrode, at atmospheric pressure in a temperature range of 160–300°C under an AC or a pulsed discharge condition.It was found that non-equilibrium plasma and a catalyst had a synergistic effect on the ethanol conversion rate under an AC discharge. For example, the ethanol conversion rate obtained with the plasma reactor with the alumite catalyst (Cu-Ni/γ-Al2O3) electrode under an AC discharge condition of 3 kV of effective voltage at 2 kHz was 2.4 times as large as the arithmetic sum of the ethanol conversion rate obtained with the plasma reactor with a non-catalytic alumite electrode under the same discharge conditions and the ethanol conversion rate obtained with the alumite catalyst (Cu-Ni/γ-Al2O3) electrode without any discharge, at 210°C. It was also observed that non-equilibrium plasma and a catalyst had a synergistic effect on the ethanol conversion rate under a pulsed discharge. For example, the ethanol conversion rate obtained with the plasma reactor with the alumite catalyst (Cu-Ni/γ-Al2O3) electrode under a pulsed discharge of 7.2 kV of peak-to-peak voltage at a pulse number of 5000 s–1 was 1.9 times as large as the arithmetic sum of the ethanol conversion rate obtained with the plasma reactor with the non-catalytic alumite electrode under the same discharge conditions and the ethanol conversion rate obtained with the alumite catalyst (Cu-Ni/γ-Al2O3) electrode without any discharge, at 180°C.The energy efficiency, which was defined as mols of hydrogen produced per unit electric power consumption, obtained with the alumite catalyst (Cu-Ni/γ-Al2O3) electrode at 270°C under conditions of an AC discharge of 3 kV of effective voltage at 2 kHz was 2.9 times higher than that obtained with the non-catalytic alumite electrode at 270°C under the same discharge conditions. The energy efficiency obtained with the alumite catalyst (Cu-Ni/γ-Al2O3) electrode at 270°C under conditions of a pulsed discharge, pulse number of 5000 s–1 and peak-to-peak voltage of 7.2 kV was 2.6 times higher than that obtained with the non-catalytic alumite electrode at 270°C under the same discharge conditions. And the energy efficiency obtained with the alumite catalyst (Cu-Ni/γ-Al2O3) electrode at 270°C under conditions of a pulsed discharge, pulse number of 5000 s–1 and peak-to-peak voltage of 7.2 kV was 2.7 times higher than that obtained under conditions of an AC discharge, frequency of 2 kHz and effective voltage of 3 kV.The energy efficiency and the conversion rate increased greatly because of the collaborative activity of the catalyst and non-equilibrium plasma. These results indicate the potential for developing a non-equilibrium reactor using an alumite catalyst electrode.