An advanced kinetic approach to the multistep thermal dehydration of calcium sulfate dihydrate under different heating and water vapor conditions: kinetic deconvolution and universal isoconversional analyses

Abstract

This study aims to identify the kinetic features of individual reaction steps of the multistep thermal dehydration of calcium sulfate dihydrate (CS-DH) to anhydride via hemihydrate (CS-HH) intermediate by achieving...

Acceleration Effect of Atmospheric Water Vapor on the Thermal Decomposition of Calcium Carbonate: A Comparison of Various Resources and Kinetic Parameterizations

“…Therefore, the kinetic behavior of the thermal decomposition of CaCO 3 at a select temperature and p (H 2 O) value can be simulated using a single set of kinetic parameters involving the exponent a in the AF. This is the primary benefit of the universal kinetic description for the thermal decomposition of solids considering the effect of atmospheric gas, which has already been demonstrated for the thermal dehydration/decomposition retarded by the effect of the product gas. − …”

“…Focusing on the thermal decomposition of CaCO 3 , the effects of the reaction atmosphere are crucial to gaining further insight into the heterogeneous kinetics. The retardation effect of atmospheric CO 2 on the thermal decomposition of CaCO 3 is a rather general phenomenon observable in the reversible thermal dehydration and decomposition of inorganic solids and can be explained by considering the contribution of the reverse reaction under atmospheric conditions with the greater partial pressure of the gaseous product. ,,,,− This phenomenon can be described kinetically by introducing an accommodation function (AF) comprising the partial pressure of the gas and the equilibrium pressure of the reaction to the kinetic equation, as recently demonstrated in the thermal dehydration and decomposition of different inorganic solids by achieving the universal kinetic description under different temperatures and partial pressures of the gas. − The universal kinetic description was also achieved for the thermal decomposition of CaCO 3 by considering the partial pressure of CO 2 and the equilibrium pressure of the reaction (eq ). ,, The other atmospheric condition influencing the thermal decomposition of CaCO 3 is water vapor pressure ( p (H 2 O)).…”

Effect of atmospheric water vapor on independent-parallel thermal dehydration of a compacted composite of an inorganic hydrate: sodium carbonate monohydrate grains comprising crystalline particles and a matrix

“…Extended experimental master plots universally describing the isothermal kinetic behavior over different p (H 2 O) values can be drawn based on eqn (11). 5,6,63 …”

Physico-geometrical kinetics of the thermal dehydration of sodium carbonate monohydrate as a compacted composite of inorganic hydrate comprising crystalline particles and matrix

“…Thus, the apparent kinetic behavior varies with the thickness of the sample bed and sample mass, [20][21][22] which also regulates the reaction geometry of the sample particle assemblage and varies the reaction pathways of some reactions, producing a thermodynamically stable intermediate compound under a self-generated condition, as observed for the thermal dehydration of calcium sulfate dihydrate. [23][24][25] Furthermore, a compacted agglomerate of reactant particles is one possible form of a solid reactant in the thermal decomposition, as typically seen for granulated malachite (Cu 2 CO 3 (OH) 2 ) 26,27 and sodium percarbonate (Na 2 CO 3 Á(3/2)H 2 O 2 ), 28,29 for which the functionality is further increased by granulation. A detailed kinetic understanding of the thermal decomposition of granular malachite and sodium percarbonate is necessary for producing a granular CuO catalyst for different reactions and evaluating its thermal stability as a safety assessment due to its oxidizing property, respectively.…”