Investigation of the Elementary Reaction Mechanism of Surface Mediated Formation of PCDD/F from Aromatic Precursors

芳香族前体表面介导生成PCDD/F的基本反应机理研究

• 批准号: 9618433
• 负责人: Barry Dellinger
• 金额: $ 16.63万
• 依托单位: University of Dayton
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-05-15 至 1998-12-15
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9618433&HistoricalAwards=false
• 关键词: Investigation; Elementary; Reaction; Mechanism; Surface

Abstract CTS 96-18433 Dellinger This is a study of the mechanism of formation of polychlorinated dibenzodioxins (PCDD) polychlorinated dibenzofurans (PCDF), and related compounds (collectively PCDD/F). Previous work haq shown the process to be catalyzed by fly ash in the range of 250-400(C. Transition metals such as iron and copper also seem to catalyze the formation of these materials. A search for evidence of surface mediated reactions tests a hypothetical mechanism for the process. Samples containing various combinations of silicate and alumina glasses (surrogates for fly ash), organic precursors (chlorobenzenes, phenol, and other aromatic compounds), and chlorinating agents (chlorine, hydrogen chloride, and transition metal chlorides) are prepared using resistively heated wafers in a special adsorption cell. Chemisorption, Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), laser-induced fluorescence spectroscopy (LIF), micro-Raman spectroscopy, and other instrumental and wet chemical techniques are used to probe reaction intermediates. From these data, an elementary chemical reaction and kinetic model for the formation of PCDD/F is developed. Elimination of emissions containing polychlorinated dibenzodioxins and dibenzofurans (PCDD/F) from combustion sources is among the most pressing of environmental issues. An improved understanding of the origin and mechanism of formation of PCDD/F may lead to a strategy to avoid their formation by process modification (pollution prevention), obviating the need for post-process control measures.

摘要CTS 96-18433 Dellinger 这是一项关于多氯二苯并二恶英（PCDD）、多氯二苯并呋喃（PCDF）和相关化合物（统称PCDD/F）形成机理的研究。以前的工作表明，在250-400 ℃范围内，粉煤灰可催化该过程。 过渡金属如铁和铜似乎也催化这些材料的形成。 对表面介导反应的证据的搜索测试了该过程的假设机制。 含有硅酸盐和氧化铝玻璃（粉煤灰的替代品）、有机前体（氯苯、苯酚和其他芳香族化合物）和氯化剂（氯、氯化氢和过渡金属氯化物）的各种组合的样品是在特殊吸附池中使用电阻加热晶片制备的。 化学吸附、傅里叶变换红外光谱（FTIR）、X射线光电子能谱（XPS）、激光诱导荧光光谱（LIF）、显微拉曼光谱和其他仪器和湿化学技术用于探测反应中间体。从这些数据，一个基本的化学反应和动力学模型的PCDD/F的形成。 消除燃烧源排放的多氯二苯并二恶英和多氯二苯并呋喃是最紧迫的环境问题之一。 对多氯二苯并对二恶英和多氯二苯并呋喃的来源和形成机制有了更好的了解，可能会导致采取一项战略，通过改变工艺（防止污染）来避免其形成，从而消除对工艺后控制措施的需要。