Mechanism investigation of carboxyl functional groups catalytic oxidation in coal assisted water electrolysis cell

Kaikai Kou, Wei Zhou, Shuai Chen and Jihui Gao

Energy, 2021, vol. 226, issue C

Abstract: The electric energy consumption for H2 production can be significantly reduced by integrating chemical energy of coal in the coal assisted water electrolysis (CAWE) process. While the oxidation mechanism of coal has not been comprehensively demonstrated. In this work, the oxidation mechanism of carboxyl group, a typical oxygen-functional group of coal, was systematically investigated by preparing a model compound of carboxylated graphene. For direct oxidation of carboxylated graphene (GCM), the onset potential was close to 1.2 V at ambient temperature. The apparent activation energy for hydrogen production was dramatically diminished by electrolysis of GCM slurry. The products analysis indicated that carboxyl groups can be oxidized to CO and CO2 at 90 °C around 1.6 V Fe3+ was sufficient to oxidize carboxyl groups to generate Fe2+ at 90 °C. The chemical oxidation of carboxyl groups was a first-order reaction accompanied by adsorption, oxidization and desorption stages. In the presence of Fe2+/Fe3+, electrolysis initiated at about 0.5 V. A gentle slope of voltage from 0.6 V to 1.2 V was observed in the continuous electrolysis and the regeneration of Fe2+ became the limiting step for a long period of time. The results are essential to guide the application of CAWE.

Keywords: Coal; Water electrolysis; Hydrogen production; Carboxyl groups; Oxidation mechanism (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:226:y:2021:i:c:s0360544221004928

DOI: 10.1016/j.energy.2021.120243

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