Kinetics and mechanisms of the thermal decomposition of copper(II) hydroxide under different water vapour pressures

Masahiro Fukuda (1, 2, 3) , Nobuyoshi Koga (1, 2, 3) , Loïc Favergeon (4, 5, 6, 7, 8, 9)

1 Department of Science Education
2 Graduate School of Education
3 Hiroshima University
4 Mines Saint-Étienne MSE - École des Mines de Saint-Étienne
5 Université de Lyon
6 CNRS - Centre National de la Recherche Scientifique
7 LGF-ENSMSE - Laboratoire Georges Friedel
8 SPIN-ENSMSE - Centre Sciences des Processus Industriels et Naturels
9 PTSI-ENSMSE - Département Procédés de Transformations des Solides et Instrumentation

Thermal decomposition of Cu(OH)₂ exhibits specific physico-geometric kinetic characteristics involving the significant induction period (IP) and subsequent sigmoidal mass-loss behaviour under isothermal conditions and the two-step mass-loss process with a long lasting reaction tail under linearly increasing temperature conditions. In addition, the rate behaviours of IP and mass-loss process are largely influenced by the environmental water vapour pressure, p(H₂0). The IP at a constant temperature is prolonged with increasing p(H₂0). The mass-loss curves shift systematically to higher temperatures with increasing p(H₂0). Therefore, the kinetic approach to this complex reaction requires the detailed considerations of the mechanistic features and the impact of p(H₂0). For the universal kinetic approach to each kinetic process under different p(H₂0), an accommodation function with respect to p(H₂0) was derived: cf. file abstract. The accommodation function a(p(H₂0), P_eq(T)) can be introduced into different kinetic equations for describing the IP and mass-loss process. The IP at different temperatures and under different p(H₂0) analysed kinetically by a single Arrhenius-type plot, providing a statistically significant linearity and the activation energy E_a,IP = 243 ± 13 kJ mol^-1. Similarly, a(p(H₂0), P_eq(T)) is introduced into the isoconversional kinetic equation for analyzing universally the mass-loss process under different temperature conditions and p(H20). The isoconversional plots applied to the major mass-loss step of the thermal decomposition of Cu(OH)₂ represent straight lines and the average E_a,l = 148 ± 1 kJ mol^-l (Fig. 1) (cf. file abstract). Furthermore, the overall thermal decomposition of Cu(OH)₂ under isothermal conditions can be described by the IP-surface reaction (SR)-phase boundary controlled reaction (PBR) model. The rate constants of each component reaction step determined under different p(H₂0) are subjected to the Arrhenius plot by considering a(p(H₂0), P_eq(T)).

Mots clés: Cu(OH)₂ decomposition; kinetic analysis; water wapor pressure

Domaines: Génie des procédés

Masahiro Fukuda, Nobuyoshi Koga, Loïc Favergeon. Kinetics and mechanisms of the thermal decomposition of copper(II) hydroxide under different water vapour pressures. ESTAC12 - The 12^th European Symposium on Thermal Analysis and Calorimetry, Central and Eastern European Committee for Thermal Analysis and Calorimetry (CEEC-TAC); Transilvania University of Brasov (UniTBv); National Institute for Laser, Plasma and Radiation Physics (INFLPR); Institute of Physical Chemistry "Ille G. Murgulescu" of the Romanian Academy (ICF); Commission for Thermal Analysis & Calorimetry of the Romanan Academy (CATCAR), Aug 2018, Brasov, Romania. pp.424 / PS2.058. ⟨hal-01898543⟩