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Issue 30, 2019

Thermodynamics and reaction mechanism of urea decomposition

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Abstract

The selective catalytic reduction technique for automotive applications depends on ammonia production from a urea–water solution via thermolysis and hydrolysis. In this process, undesired liquid and solid by-products are formed in the exhaust pipe. The formation and decomposition of these by-products have been studied by thermogravimetric analysis and differential scanning calorimetry. A new reaction scheme is proposed that emphasizes the role of thermodynamic equilibrium of the reactants in liquid and solid phases. Thermodynamic data for triuret have been refined. The observed phenomenon of liquefaction and re-solidification of biuret in the temperature range of 193–230 °C is explained by formation of a eutectic mixture with urea.

Graphical abstract: Thermodynamics and reaction mechanism of urea decomposition

Supplementary files

Article information


Submitted
18 Mar 2019
Accepted
05 Jul 2019
First published
08 Jul 2019

This article is Open Access

Phys. Chem. Chem. Phys., 2019,21, 16785-16797
Article type
Paper

Thermodynamics and reaction mechanism of urea decomposition

S. Tischer, M. Börnhorst, J. Amsler, G. Schoch and O. Deutschmann, Phys. Chem. Chem. Phys., 2019, 21, 16785 DOI: 10.1039/C9CP01529A

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