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Ab Initio Study On The Microscopic Mechanism Of Ozone Depletion In Atmosphere And The Reaction In Combustion

Posted on:2004-08-28Degree:DoctorType:Dissertation
Country:ChinaCandidate:L C LiFull Text:PDF
GTID:1101360095453641Subject:Physical chemistry
Abstract/Summary:PDF Full Text Request
In the first section of this paper, mechanism and kinetics of ozone depletion by F, Cl, CHX(X=H, F, Cl, Br), CH,CHX(X=H, F, Cl), NH, OH, CH3, NH2, C,H, etc. seventeen active free radicals or molecules, have been studied by the present quantum chemical calculation programs and methods, and the reaction rate constants have been also calculated to compare with the experimental data or to predict the reaction without the corresponding experimental data. We have found out 22 reaction pathways, 27 intermediates and 36 transition states in this section. Our purpose of this study is to find out the main chemicals depleting ozone in stratosphere. Thus the experiments can be performed to protect the ozone layer according to the theoretical results. For these reactions depleting ozone in atmosphere are small molecules reactions, we used the Gausssian-3(G3) method developed recently which is one of the most accurate method at present. Our results show that reducing agents in air, such as small active molecules and free radicals, will deplete the ozone layer, and all the reactions are exothermic.The second section of this paper is the mechanism and kinetics of the reaction between small molecules in coal combustion. During the process of coalcombustion, trace poisonous elements such as Hg, As, Sn and Pb, may be emittedinto atmosphere, which will pollute the air and do harm to the health of humans. Thus, the research on the mechanism and kinetics of such reaction has been a focus of understanding the influence of coal combustion on the air for scientists. In this paper, we put emphasis upon the reaction mechanism and kinetics of mercuric and stannic oxidation by oxidants. Up to date, the experiments showed that mercuric chloride species were the main products of mercuric oxidation, but the microscopic mechanism and kinetics of it were not well understood. Therefore, we want to give a reasonable explanation theoretically through our study. At the same time, we calculated the reaction rate constants of the mercuric oxidation by chlorine species to compare with the corresponding experimental data. As to the stannic oxidation by oxidants, we have studied the microscopic mechanism and kinetics of stannic oxidation by HOCl, HCl, OCl, OCl, and NO3, and calculated the rate constants of them to enrich the database for there are still no the corresponding experimental data at present. Aggregately, we computed 24 reaction pathways, and found out 26 intermediates and 36 transition states in this section. During the period of studying for the degree of Doctor, I have written twenty-nine pieces of articles, of which twenty-five have been published in journals (five have been published in core journals) and fourteen have been embodied by SCI.
Keywords/Search Tags:Ozone, the reaction mechanism, Transition states
PDF Full Text Request
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