The Physical Kinetics of Reversible Thermal Decomposition

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F49777513%3A23640%2F17%3A43950534" target="_blank" >RIV/49777513:23640/17:43950534 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1007/978-3-319-45899-1_17" target="_blank" >http://dx.doi.org/10.1007/978-3-319-45899-1_17</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1007/978-3-319-45899-1_17" target="_blank" >10.1007/978-3-319-45899-1_17</a>

Jazyk výsledku

angličtina

Název v původním jazyce

The Physical Kinetics of Reversible Thermal Decomposition

Popis výsledku v původním jazyce

A new theoretical basis, fitting thermal analysis of solids more adequately than the Arrhenius equation developed for reacting gas molecules, is proposed for gas-evolving reversible decompositions. Such complex processes are theoretically dissected into elementary steps, showing distinctions between microkinetics and macro-kinetics; only the slowest step being recordable thermoanalytically. Practical procedures of determination whether a thermoanalytical process is controlled by chemical kinetics on micro-level, or by physical macro-processes of heat- and gas-transport in the bulk, based on exposing the samples to changing degrees of heat transfer, and (separately) to the changing degree of exposure to the gaseous decomposition product, are postulated as a prerequisite before choosing the calculation model. It is shown that many typical processes of gas-evolving reversible decomposition are controlled not by chemical micro-kinetics, but by the physical processes of escaping of the gases and of the heat transfer. Even in smallest samples, the overlapping gradients of the temperature and of the gas concentration, plus two or three interwoven reaction fronts, invalidate micro-kinetic calculations and indicate that thermoanalytical data reflect globally the behavior of the sample as a whole, not of its individual grains or molecules—those two classes being completely different. The meaning of decomposition temperature is revisited. A family of TG curves obtained at the specified conditions enables distinguishing between the true decomposition temperature and the procedural one; only the latter being normally recorded. A pitfall of determination of decomposition temperature by CRTA is discussed. Implication for industrial processes are suggested.

Název v anglickém jazyce

The Physical Kinetics of Reversible Thermal Decomposition

Popis výsledku anglicky

A new theoretical basis, fitting thermal analysis of solids more adequately than the Arrhenius equation developed for reacting gas molecules, is proposed for gas-evolving reversible decompositions. Such complex processes are theoretically dissected into elementary steps, showing distinctions between microkinetics and macro-kinetics; only the slowest step being recordable thermoanalytically. Practical procedures of determination whether a thermoanalytical process is controlled by chemical kinetics on micro-level, or by physical macro-processes of heat- and gas-transport in the bulk, based on exposing the samples to changing degrees of heat transfer, and (separately) to the changing degree of exposure to the gaseous decomposition product, are postulated as a prerequisite before choosing the calculation model. It is shown that many typical processes of gas-evolving reversible decomposition are controlled not by chemical micro-kinetics, but by the physical processes of escaping of the gases and of the heat transfer. Even in smallest samples, the overlapping gradients of the temperature and of the gas concentration, plus two or three interwoven reaction fronts, invalidate micro-kinetic calculations and indicate that thermoanalytical data reflect globally the behavior of the sample as a whole, not of its individual grains or molecules—those two classes being completely different. The meaning of decomposition temperature is revisited. A family of TG curves obtained at the specified conditions enables distinguishing between the true decomposition temperature and the procedural one; only the latter being normally recorded. A pitfall of determination of decomposition temperature by CRTA is discussed. Implication for industrial processes are suggested.

Druh

C - Kapitola v odborné knize

CEP obor

—

OECD FORD obor

10403 - Physical chemistry

Projekt

<a href="/cs/project/LO1402" target="_blank" >LO1402: CENTEM+</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2017

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název knihy nebo sborníku

Thermal Physics and Thermal Analysis

ISBN

978-3-319-45897-7

Počet stran výsledku

22

Strana od-do

363-384

Počet stran knihy

567

Název nakladatele

Springer International Publishing

Místo vydání

Cham, Switzerland

Kód UT WoS kapitoly

—