Additional pathways for the ethanol electro-reforming knowledge: The role of the initial concentration on the product yields

Ethanol electrochemical reforming mechanism on bimetallic PtRu/C catalyst was studied in a proton exchange membrane cell at 80 degrees C. In this work, we report for the first time the ethyl acetate pathway in acid media, evaluating all the possible chemical routes that may be involved in the ethanol oxidation reaction. Chronopotentiometry and open circuit voltage essays were conducted for different reactant compositions to explore each pathway nature individually. Among all processes, only ethyl acetate follows a non-electrocatalytic mechanism (via hemiacetal) with the consequent over-faradaic hydrogen production. The influence of the initial concentration on the product yields was studied for a wide range of ethanol solutions (0.5-6 M) and applied current levels (0.2-1.4 A). Promising current density values were obtained (1000 mA cm(-2), 1.4 V) for high ethanol concentrations (4-6 M), which led to high conversion rates. Additionally, losses in the electrocatalytic activity took place for 0.5-3 M solutions at potentials close to 1 V due to mass transfer limitations. Regarding product distribution (apart from H-2), low concentration levels increased the acetic acid yield, while more concentrated solutions boosted the acetaldehyde and ethyl acetate generation. Finally, the required power to achieve 1 kg of each reaction product was estimated.

Automated summary

In this study, the mechanism of ethanol electrochemical reforming on bimetallic PtRu/C catalyst was investigated at 80 degrees C in a proton exchange membrane cell. The existence of the ethyl acetate pathway in acid media was reported for the first time, along with evaluation of possible chemical routes involved in the ethanol oxidation reaction. Different reactant compositions were explored through chronopotentiometry and open circuit voltage essays to study each pathway individually, with ethyl acetate found to follow a non-electrocatalytic mechanism leading to over-faradaic hydrogen production.