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研究报告

摘要：采用量子化学计算研究了OH自由基降解八氯代二苯并对-二英（OCDD）的微观反应机理，计算分析了微观反应进程，结果表明该反应存在两条途径：①α-氯取代：1，4，6，9位置氯取代，该路径反应活化能较高，反应难以进行，并以中间产物积聚，无法使OCDD的毒性消失；②β-氯取代：2，3，7，8位置氯取代，该路径的反应能相对较低，且能使OCDD的毒性消失，是有效降解OCDD的主要途径.结合过渡态理论，计算获得动力学参数：反应活化能为8.32 kJ·mol^-1（B3LYP/6-311G++（d，g）//B3LYP/6-31G（d）），阿仑尼乌斯表达式为k=1.29×10¹⁴exp（-1049.6/T）（cm³·mole^-1·s^-1）.这与文献实验结果取得了很好的吻合，说明本文对OH自由基降解OCDD的反应机理及动力学研究是合理且可靠的.本文的计算结果可为催化氧化降解二英的进一步研究提供理论参考.

Abstract：The destruction mechanism of OCDD by OH radical is investigated in detail by Quantum Chemical Calculations in this paper. Results show that, there are two paths for the reaction of OCDD+OH:① α-Cl substitution:at the 1,4,6,9 position, OCDD can not be destructed effectively because of its high energy barrier, and the toxic also can not fade away because the intermediates are accumulated; ② β-Cl substitution:at the 2,3,7,8 position, the effective path for the destruction because its activation energy is quit low and the intermediates are not accumulated. The kinetic parameters are also calculated by transition state theory. The activate energy obtained by the B3LYP/6-311G++(d,g)//B3LYP/6-31G(d) method is 8.32 kJ·mol^-1, and the calculated Arrenius expression is that k=1.29×10¹⁴ exp(-1049.6/T) (cm³·mole^-1·s^-1). This theoretical results are in good agreement with the literature experimental results, indicating that the quantum chemistry study and kinetics of OH radical degradation of OCDD are reasonable and reliable. The study in this paper would supply important theory basis for the further investigation on dioxins removal by using the catalytic oxidation technology.