摘要
氯苯作为一种含氯代苯环的物质,具有高生物毒性和化学稳定性,难以降解,亟需治理。在诸多治理技术中,催化氧化法因深度降解能力有较好的应用前景。本研究基于资源丰富的稀土金属氧化物CeO_(2),探究了不同制备方法以及不同过渡金属元素掺杂对催化氧化氯苯活性的影响,分析了催化剂的理化性能和反应路径。结果显示,与直接焙烧、乙酸+水热,尿素水解+水热等方法相比,NaOH沉淀+水热法合成的CeO_(2)催化剂性能较好。通过掺杂不同元素(Mn、Fe、Co)发现,Ce-Mn催化剂的氯苯氧化活性的提升效果较为明显,于450℃、含H_(2)O(5%(体积分数,下同))条件下取得95%的催化转化率。分析表明,Mn掺杂后催化剂表面酸性位点以及氧化还原位点显著增加,其中Br nsted/Lewis(B/L)酸比值由0.259升高至0.419,促进了更多的电子循环(Ce^(4+)Ce^(3+))以及氧物种迁移(OαOβ)产生。反应路径研究表明,氯苯分子首先吸附在催化剂表面的活性位点(酸位点或氧空位)上发生亲核取代反应,脱氯形成苯酚/苯醌等物质,在活性氧物种的作用下,逐渐开环氧化为乙酸盐等中间物种,最终转化为CO_(2)、H_(2)O和HCl等小分子的最终产物。
Chlorobenzene,as a chlorobenzene ring substance,has high biological toxicity and chemical stability,is difficult to degrade,and needs urgent treatment.Among many treatment technologies,catalytic oxidation has a good application prospect because of its deep degradation ability.In this study,based on the rare earth metal oxide CeO_(2),which is rich in resources,the effects of different preparation methods and doping of different transition metal elements on the catalytic oxidation of chlorobenzene were investigated.The physicochemical properties and reaction paths of the catalyst were analyzed and the results showed that compared with the direct calcination,acetic acid+hydrothermal,urea hydrolysis+hydrothermal methods,the CeO_(2)catalyst prepared by NaOH precipitation+hydrothermal method has better performance.The study of doping with different elements(Mn,Fe,Co)found that the chlorobenzene oxidation activity of Ce-Mn catalyst was significantly improved,and the catalytic conversion rate was 95%at 450℃containing H_(2)O(5vol%,the same below).The analysis showed that Mn doping significantly increased the acidic sites and REDOX sites on the surface of the catalyst,and the Br nsted/Lewis(B/L)acid ratio was increased from 0.259 to 0.419,which promoted more electron cycling(Ce^(4+)Ce^(3+))and reactive oxidizing species mobility(OαOβ).Chlorobenene molecules adsorbed on the active site(acid site or oxygen vacancy)on the catalyst surface underwent nucleophilic substitution reaction,dechlorinated to form phenol.Under the action of reactive oxygen species,chlorobenene gradually opened to intermediate species such as acetate,and finally converted to small molecular products such as CO_(2),H_(2)O and HCl.
作者
罗宁
高凤雨
陈都
张辰骁
段二红
赵顺征
易红宏
唐晓龙
LUO Ning;GAO Fengyu;CHEN Du;ZHANG Chenxiao;DUAN Erhong;ZHAO Shunzheng;YI Honghong;TANG Xiaolong(School of Energy and Environmental Engineering,University of Science and Technology Beijing,Beijing 100083,China;School of Environmental Science and Engineering,Hebei University of Science and Technology,Shijiazhuang 050018,China)
出处
《材料导报》
EI
CAS
CSCD
北大核心
2024年第16期35-43,共9页
Materials Reports
基金
国家重点研发计划(2023YFB3810800)
国家自然科学基金(U20A20130)
中央高校基本科研业务费专项资金(FRF-EYIT-23-07)。
关键词
CeMn氧化物
水热法
元素掺杂
氯苯降解
催化氧化
反应路径
CeMn oxide
hydrothermal method
element doping
chlorobenzene degradation
catalytic oxidation
reaction pathway
