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Mechanism of dehydroxylation temperature decrease and high temperature phase transition of coal-bearing strata
Hongfei Cheng1, Qinfu Liu, Xiaonan Cui
1School of Geoscience and Surveying Engineering, China University of Mining & Technology, Beijing 100083, China.
Journal of Colloid and Interface Science
|April 3, 2012
Summary
Intercalating coal-bearing strata kaolinite with potassium acetate (KAc) enhances thermal decomposition. This KAc intercalation complex shows a new mass loss peak and reduced dehydroxylation temperatures, facilitating easier kaolinite dehydroxylation.
Area of Science:
- Materials Science
- Geochemistry
- Mineralogy
Background:
- Coal-bearing strata kaolinite is a common clay mineral.
- Understanding its thermal behavior is crucial for various applications.
- Intercalation can modify clay mineral properties.
Purpose of the Study:
- To investigate the thermal decomposition and dehydroxylation of a coal-bearing strata kaolinite-potassium acetate intercalation complex (CSKK).
- To analyze the structural and thermal property changes induced by potassium acetate intercalation.
- To propose a structural model for the CSKK.
Main Methods:
- X-ray Diffraction (XRD) for structural analysis.
- Infrared Spectroscopy (IR) for chemical bonding.
- Thermal Analysis (TGA/DSC) for thermal stability and decomposition.
- Mass Spectrometry for identifying decomposition products.
- Infrared Emission Spectroscopy.
Main Results:
- Successful intercalation of potassium acetate (KAc) into kaolinite, increasing basal spacing.
- Formation of KHCO(3), KCO(3), and KAlSiO(4) upon heating CSKK.
- CSKK is stable below 300°C, with H(2)O and CO(2) as decomposition products.
- A new mass loss peak at 285°C and a ~100°C decrease in dehydroxylation/dehydration temperatures for CSKK compared to raw kaolinite.
- Weakened interlayer hydrogen bonds due to increased interlayer spacing.
Conclusions:
- Potassium acetate intercalation significantly alters the thermal decomposition and dehydroxylation behavior of coal-bearing strata kaolinite.
- The increased interlayer space facilitates easier dehydroxylation.
- A potential structural model for CSKK has been proposed, warranting further investigation.
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