Clean hydrogen generation from the electrocatalytic oxidation of methanol inside a proton exchange membrane electrolysis cell (PEMEC): effect of methanol concentration and working temperature

Abstract

The electrochemical decomposition of methanol (MeOH) for hydrogen production has been carried out at several temperatures (25–85 °C) and different methanol concentrations (0.1 to 10 M in 0.5 M H2SO4) using a Direct Methanol Fuel Cell (DMFC) hardware working as a Proton Exchange Membrane Electrolysis Cell (PEMEC). The cell voltages and the volume of generated hydrogen were recorded as a function of time for each current density and each methanol concentration at the different investigated temperatures. The maximum cell voltage (corrected from ohmic losses) did not exceed 0.55 V so that the electrical energy consumed was less than 1.2 kWh (Nm3)−1, i.e., less than a quarter of the energy needed for water electrolysis, which is around 5–6 kWh (Nm3)−1. The volume of generated hydrogen is a linear function of the electrolysis time and current intensity, i.e., of the quantity of electricity involved in the electrochemical process according to Faraday’s law. Moreover, the quantity of produced hydrogen only depends on the current intensity irrespective of methanol concentration, working temperature, cell voltage, and nature of the anode catalyst. However, the electrical energy consumed depends greatly on the working temperature and on the nature of the anode catalyst, since it is related to the cell voltage, i.e., to the kinetics of the anodic process at a given current intensity.