Physico-geometrical kinetic insight into multistep thermal dehydration of calcium hydrogen phosphate dihydrate

Hara, Mitsuhiro; Koga, Nobuyoshi

doi:10.1039/d3cp01323e

Cited by 3 publications

(1 citation statement)

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“…A typical phenomenon is the formation of a surface product layer in the initial stage of both dehydration and rehydration reactions. [10][11][12][13][14][15] The surface product layer sometimes blocks the diffusional removal of water vapor generated at the reaction interface during thermal dehydration and the intake of water vapor during rehydration, temporarily stopping the reaction. The reaction is reactivated by the formation of diffusion channels in the surface product layer, possibly because of the crystal growth of the solid product and crack formation.…”

Section: Introductionmentioning

confidence: 99%

The physico-geometrical reaction pathway and kinetics of multistep thermal dehydration of calcium chloride dihydrate in a dry nitrogen stream

Kato,

Koga

2024

Phys. Chem. Chem. Phys.

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Section: Introductionmentioning

confidence: 99%

The physico-geometrical reaction pathway and kinetics of multistep thermal dehydration of calcium chloride dihydrate in a dry nitrogen stream

Kato,

Koga

2024

Phys. Chem. Chem. Phys.

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Multistep kinetics in self-induced sol–gel process of amorphous anhydride formation during thermal dehydration of potassium tetraborate tetrahydrate

Shindo,

Koga

2024

J Therm Anal Calorim

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The physico-geometrical mechanism and kinetics of the multistep thermal dehydration of potassium tetraborate tetrahydrate was investigated as a model reaction to produce amorphous anhydrate via the self-induced sol–gel process. The thermal dehydration is composed of three consecutive dehydration steps: (1) a surface reaction in the solid-state accompanied by crack formation; (2) a rapid mass loss process accompanied by liquefaction to form the aggregate of the gel powders; and (3) the dehydration of gel powder aggregate to form a glassy anhydride. The changes in the contribution of the individual dehydration steps to the overall process according to the sample particle size and the heating rate (β) were identified as specific features of the multistep dehydration, which was characterized quantitatively using mathematical deconvolution analysis with log-normal four-parameter functions. The difficulty in determining the apparent activation energy (Ea) of the individual dehydration steps using isoconversional analysis due to the changes in the contribution depending on β values was addressed using modulated temperature thermogravimetry. Using the contributions and the apparent Ea of the individual dehydration steps as initial values, the kinetic description of the multistep thermal dehydration was refined through a kinetic deconvolution analysis using the cumulative kinetic equation. As a result, the individual dehydration steps were kinetically characterized as: (1) a surface reaction described by the first-order rate law with Ea,1 of approximately 68 kJ mol−1; (2) a reaction accompanied by liquefaction controlled by an autocatalytic rate behavior with Ea,2 of approximately 123 kJ mol−1; (3) a diffusion-controlled dehydration of gel powder with Ea,3 of approximately 82 kJ mol−1.

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Swing processes for natural gas dehydration: Pressure, thermal, vacuum, and mixed swing processes

Hashemzadeh,

Rahimpour

2024

Advances in Natural Gas: Formation, Processing, and Applications

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Physico-geometrical kinetic insight into multistep thermal dehydration of calcium hydrogen phosphate dihydrate

Abstract: The origin of the multistep thermal dehydration of calcium hydrogen phosphate dihydrate (dibasic calcium phosphate dihydrate (DCPD)) to form γ-calcium diphosphate (γ-calcium pyrophosphate (γ-CPP)) via calcium hydrogen phosphate anhydride (dibasic...

Cited by 3 publications

References 69 publications

The physico-geometrical reaction pathway and kinetics of multistep thermal dehydration of calcium chloride dihydrate in a dry nitrogen stream

The physico-geometrical reaction pathway and kinetics of multistep thermal dehydration of calcium chloride dihydrate in a dry nitrogen stream

Multistep kinetics in self-induced sol–gel process of amorphous anhydride formation during thermal dehydration of potassium tetraborate tetrahydrate

Swing processes for natural gas dehydration: Pressure, thermal, vacuum, and mixed swing processes

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