Indirect urea electrooxidation by nickel(III) in alkaline medium: From kinetic and mechanism to reactor modeling

This study consists in the determination of two kinetic laws of urea oxidation (UO) and electrooxidation (UEO) in alkaline media on nickel(III). Two kinds of active sites were examined, the first one derived from a Ni(OH)2 powder and the second from a massive nickel electrode. Partial orders of nick...

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Bibliographic Details
Published in:AIChE journal 2023-09, Vol.69 (9), p.n/a
Main Authors: Hopsort, Guillaume, Latapie, Laure, Groenen Serrano, Karine, Loubière, Karine, Tzedakis, Theodore
Format: Article
Language:English
Subjects:
Ammonia
Catalysis
Chemical engineering
Chemical Sciences
Computer Science
Electrolysis
Engineering Sciences
heterogeneous coupled reactions
mechanism and kinetics
Modeling and Simulation
Ni(III)/Ni(II) mediator
Nickel
Nitrogen dioxide
Oxidation
Transport phenomena
transport phenomena modeling
Urea
urea electrooxidation
Ureas
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Summary:This study consists in the determination of two kinetic laws of urea oxidation (UO) and electrooxidation (UEO) in alkaline media on nickel(III). Two kinds of active sites were examined, the first one derived from a Ni(OH)2 powder and the second from a massive nickel electrode. Partial orders of nickel(III) (two for UO and five UEO) enable to conclude about (i) the urea adsorption on two nickel(III) sites and (ii) that a multistep oxidation of urea occurs involving five nickel(III) site electroregenerations. A multipathway mechanism is also proposed to explain UEO facilitated by the nickel(III)/nickel(II) mediation system, and to predict the by‐products' formation previously identified (NO2−,NH3,OCN−,CO32−). At last, a model combining the UEO kinetic law previously established, with diffusive and convective transport phenomena was developed. A consistent correlation (maximum deviation of 6%) between laboratory electrolysis results with the model' predictions was obtained under different operating conditions, enabling the validation of this model.
ISSN:0001-1541
1547-5905
DOI:10.1002/aic.18113