有机胺对Pd/C催化氯酚加氢脱氯反应的影响

采用Pd/C催化剂，选择不同的溶剂体系，首先分别比较了有机碱Et₃N以及无机强碱NaOH对Pd/C催化2,4-二氯苯酚（2,4-DCP）加氢脱氯反应的影响。结果表明，醇类溶剂中，Et₃N作为质子吸收剂，2,4-DCP能够在Pd/C催化下高效彻底加氢脱氯。并通过SEM、XRD和XPS等表征分析，发现Et₃N能够中和加氢反应产生的HCl，生成三乙胺盐酸盐（Et₃N·HCl），从而消除HCl对催化剂的毒化作用，同时避免了因Et₃N·HCl在催化剂表面的沉积而引发的催化剂失活的问题。进一步研究了不同类型的有机胺对甲醇中Pd/C催化2,4-DCP加氢脱氯反应速率和反应选择性的影响。研究表明，短链有机胺（伯胺、仲胺和叔胺）更有利于Pd/C催化2,4-DCP加氢脱氯反应的进行。在此基础上建立一种新型Pd/C-甲醇-短链有机胺催化体系，可以高效、彻底地实现对多氯代苯酚类污染物的加氢脱氯降解，为实现温和条件下高浓度多氯代苯酚类污染物的环境友好无害化处理提供新的思路和方法。

Effect of organic amines on catalytic hydrodechlorination of chlorophenols over Pd/C catalyst

The effects of organic base triethylamine (Et₃N) and inorganic base NaOH on the liquid-phase hydrodechlorination (HDC) of 2,4-chlorophenol (2,4-DCP) over Pd/C catalyst in different solvent systems were studied. The results showed that efficient HDC of 2,?4-DCP could be achieved in methanol and ethanol with Et₃N as the proton scavenger. Meanwhile, the reaction mechanism was studied through catalyst characterization (SEM, XRD, and XPS). It was found that the byproduct HCl could be efficiently eliminated by generating Et₃N·HCl with Et₃N in methanol, which prevented the catalyst poisoning caused by HCl. Moreover, the high solubility of Et₃N·HCl in methanol prevented inorganic salts from depositing on the surface of catalyst and thereby avoided the decline in the activity and stability of the catalyst. Furthermore, the effects of different types of organic amines on the HDC rate and the selectivity of 2,4-DCP over Pd/C catalyst in methanol were investigated. Compared to long-chain organic amines, short-chain organic amines (primary amines, secondary amines, and tertiary amines) were more favorable. Based on these studies, a novel Pd/C-methanol-short-chain organic amine catalytic system was established for the efficient HDC of pollutants containing high concentration polychlorinated phenols. Thus, this study provided a vital guidance for realizing the environmentally friendly and harmless HDC treatment of the pollutants with high concentration polychlorinated phenols under mild conditions.