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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >FTIR investigation of 2-chlorophenol chemisorption on a silica surface from 200 to 500 degrees C
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FTIR investigation of 2-chlorophenol chemisorption on a silica surface from 200 to 500 degrees C

机译：FTIR研究200至500摄氏度的二氧化硅表面上的2-氯苯酚化学吸附

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摘要

The time-dependent chemisorption of 2-chlorophenol on a fumed silica surface was studied in situ from 200 to 500 C using a temperature-controlled dosing cell and FTIR absorption spectroscopy. 2-Chlorophenol was found to chemisorb at isolated and geminal surface hydroxyl sites. 2-Chlorophenol chemisorption and subsequent surface oxidation resulted in a mixture of chlorophenolate and partial oxidation products, such as formates and acetates. The rates of chemisorption were measured, and the activation energy of adsorption was found to be 15 +/- 4 kJ mol(-1) for a fast, initial reaction and 22 +/- 2 kJ mol(-1) for a slower reaction at higher surface coverage. This work was motivated by the observation that combustion-generated fly ash mediates the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) at temperatures between 250 and 450 degrees C. Although transition metals such as copper are known to catalyze or mediate this reaction, silica is the major component of fly ash and chemisorption at higher concentration surface sites of silica must have a significant impact on the surface-mediated PCDD/F formation on fly ash surfaces.
机译：使用温度控制的计量池和FTIR吸收光谱技术，研究了200℃至500℃下气相二氧化硅在气相二氧化硅表面上的时间依赖性化学吸附。发现2-氯苯酚在分离的和双亲的表面羟基位点化学吸附。 2-氯苯酚的化学吸附作用和随后的表面氧化作用产生了氯酚盐和部分氧化产物（例如甲酸酯和乙酸酯）的混合物。测量化学吸附的速率，发现对于快速的初始反应，吸附的活化能为15 +/- 4 kJ mol（-1），对于较慢的反应，吸附的活化能为22 +/- 2 kJ mol（-1）在更高的表面覆盖率。这项工作的动机是观察到，燃烧产生的粉煤灰在250至450摄氏度之间的温度下介导了多氯化二苯并对二恶英和二苯并呋喃（PCDD / F）的形成。尽管已知过渡金属（例如铜）会催化或催化介导该反应的是二氧化硅是粉煤灰的主要成分，在较高浓度的二氧化硅表面位点上的化学吸附必须对粉煤灰表面上表面介导的PCDD / F的形成产生重大影响。

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