Kinetics and 13C NMR Study of Oxygen Incorporation into PVC- and Pitch-Derived Materials

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• 作者：Gisele F. Alto^† ; ; Jair C. C. Freitas*^† ; ; Alfredo G. Cunha^† ; ; Francisco G. Emmerich^† ; ; Mark E. Smith^‡ ;
• 刊名：Energy & Fuels
• 出版年：2009
• 出版时间：March 19, 2009
• 年：2009
• 卷：23
• 期：3
• 页码：1373-1378
• 全文大小：231K
• 年卷期：v.23,no.3(March 19, 2009)
• ISSN：1520-5029

文摘

The kinetics of oxygen incorporation into a PVC-derived material with pitch-like characteristics was studied by isothermal thermogravimetric analysis at temperatures ranging from 200 to 270 °C. Activation energy, E_a, pre-exponential factor, A, and rate constants, k_T, were obtained from the weight-gain curves recorded during reactions of the material with molecular oxygen, which were analyzed following a kinetic first-order model. The numerical values obtained were E_a = 100.5 kJ/mol and A = 1.6 × 10¹⁰ h⁻¹. The extent of the oxidation at a fixed temperature was monitored by elemental analysis, and the chemical changes in the materials were followed by solid-state ¹³C NMR. The study was next extended to the chars obtained from three coal tar pitches with different softening points (55, 85, and 110 °C). Comparisons were then established between the determined kinetic parameters and the chemical/structural aspects and compositions of each analyzed material.