Impact of atmospheric water vapor on the thermal decomposition of calcium hydroxide: a universal kinetic approach to a physico-geometrical consecutive reaction in solid–gas systems under different partial pressures of product gas

Abstract

Impact of atmospheric water vapor pressure on the kinetics of the thermal decomposition of Ca(OH)2 can be described universally.

Universal Kinetic Description for Thermal Decomposition of Copper(II) Hydroxide over Different Water Vapor Pressures

“…The temperature difference between T eo and T p initially decreased in the lower p(H 2 O) region and subsequently increased with p(H 2 O) values, which was compensated by accompanying changes in the peak height at T p . The observed changes in the mass-loss behavior with p(H 2 O) are different from our previous results for the thermal decomposition of Ca(OH) 2 , 47 for which the non-isothermal mass-loss curves shifted to higher temperatures accompanied by a systematic increase in the DTG peak height with increasing p(H 2 O). A normal effect with respect to chemical equilibrium for the reversible reaction can explain the observed changes in the reaction behavior that depend on the p(H 2 O) value: Figure S2 shows the equilibrium water vapor pressure, P eq (T), at different temperatures, which was calculated using a thermodynamic database (MALT2, Kagaku Gijutsu-Sha), 60,61 together with the (T, p(H 2 O)) region applied to the TG−DTG measurements to obtain the kinePc data.…”

“…The slope of the Arrhenius plot decreased with increasing p(H 2 O) values, which was accompanied by a compensatory decrease in the intercept. Variations in the conventional Arrhenius plot, when applied to the IP process, indicate trends that are completely opposite of those previously reported for the IP process during the thermal decomposition of Ca(OH) 2 at various p(H 2 O) values, 47 in spite of the similar retardation effect that p(H 2 O) has on the IP processes. Table S1 lists the apparent Arrhenius parameters determined for the IP processes of the thermal decomposition of Cu(OH) 2 at each p(H 2 O) value.…”

“…The effectiveness of the kinetic equation (eq 1), together with the AF in eq 3, has been critically examined through stepwise kinetic analyses of thermal decomposition of Ca(OH) 2 using systematically measured mass-loss curves at different heating conditions when exposed to different, but controlled, p(H 2 O) values. 47 The isothermal decomposition of Ca(OH) 2 in the presence of atmospheric water vapor was characterized by a significant induction period (IP) and subsequent sigmoidal mass-loss behavior. Increasing the p(H 2 O) systematically reduced the reaction rate in both the IP and mass-loss processes.…”

“…Then, the universal view of the kinetic features of thermal decomposition of Cu(OH) 2 over different temperature and p(H 2 O) conditions is summarized in comparison with previously obtained kinetic results for the thermal decomposition of Ca(OH) 2 . 47 2. EXPERIMENTAL SECTION 2.1.…”

Kinetics of Solid-Gas Reactions and Their Application to Carbonate Looping Systems

“…A recent work suggests that the equilibrium pressure, P 0 (kPa), of the gaseous product has a significant influence on dα/dt and the effective E a for decomposition reactions under temperature swing cycling [46]. Various forms of the pressure dependence term (also known as the accommodation function) have been derived and used in solid-gas systems [47,48]. The following h(P) function is derived by considering the contribution of the reverse reaction (e.g.…”