The Influence of the Platinum Weight Percentage in the Catalyst Formulation on the Performance of a High Temperature Ethanol Electroreformer Based on H3PO4‑Doped Polybenzimidazole for Green Hydrogen Production

Abstract

A vapor-fed high temperature proton exchange ethanol electroreformer has been developed based on the use of a H3PO4-doped polybenzimidazole membrane to produce green hydrogen. As a key parameter, this article describes the influence of platinum weight percent (wt.%) in the catalyst formulation from different commercial catalysts (20, 40, 60, 80 wt.% Pt/C and Pt black) on the activity (related to the H2 production), energy consumption, and CO2 yields. The structural and morphological analysis reveal that an increase in Pt wt.% leads to the formation of bigger nanometric Pt particles, resulting in a decrease in the electrochemically active surface area. In terms of the ethanol electro-oxidation activity, the Pt wt.% impacts on the performance of the electroreformer, with the H2 flux that increasing from 0.22 STP (standard pressure and temperature, 273.15 K and 105 Pa) m3 m-2 h-1 for Pt black to 1.47 STP m3 m-2 h-1 for 60 wt.% Pt/C. The Pt wt.% also impacts on the CO2 percentages, increasing from values in the range of 20-40% for the 20 wt.% Pt/C to 45-55% for the optimum 60 wt.% Pt/C and, finally, decreasing to values between 30-45% for Pt black. These values are, in overall, higher than those of low temperature (< 90 °C) ethanol electro-oxidation systems.