摘要
氯化铜被认为是对二噁英(PCDD/F)生成促进作用最强的金属催化剂,温度和氧气含量是影响其催化二噁英生成的关键因素.本文选取250~550℃间8个不同温度点及0~20%间4种不同氧气含量,系统性地研究了温度和氧气含量对含氯化铜模拟飞灰(MFA)生成二噁英的影响,并通过分析指纹特性探讨二噁英的生成路径和机理.结果发现,290~350℃之间二噁英生成量较高,且在290℃时二噁英总量达到最大值;氧气含量为10%时二噁英生成量达到最高.研究二噁英同分异构体分布可从分子层面为研究其生成路径和机理提供重要信息,因此,本文分析了四至八氯代PCDD/F的全部异构体的分布.结果表明,在本文所选取的温度和氧含量范围内,温度对二噁英生成路径的影响高于氧气含量.最后,重点讨论了2,3,7,8位氯取代的17种有毒异构体的分布随温度和氧气的变化情况及生成路径.利用主成分分析法(PCA)证实了氯化铜催化二噁英从头合成过程中存在经由氯酚路径生成的异构体,并讨论了不同工况下氯酚路径对二噁英生成的影响.
Copper chloride(CuCl2)has been identified as the strongest among various catalysts for formation of polychlorinated dibenzo?p?dioxins and dibenzofurans(PCDD/F).This study systematically explores the effect of temperature and oxygen on the formation of PCDD/F from CuCl2?catalyzed system,over a wide range of temperature(250~550℃)and oxygen content(0~20%).Both PCDD/F?output and its signature are extensively characterized,including homologue and isomer profiles.The temperature range between 290 and 350℃largely promotes the formation of PCDD/F and a maximum output is reached at 290℃.An oxygen content of 10%in the gas phase is favorable for forming PCDD/F.Isomer?specific information is essential for researchers in their quest towards reaction mechanisms.In all cases a complete analysis on isomer distribution pattern is produced.Still,temperature exhibits a more significant influence on isomer profiles than oxygen content ranging from 5%to 20%.Special attention is paid to the seventeen 2,3,7,8?substituted isomers,to their behaviour and relationship.The existence of chlorophenols(CP)?route congeners in CuCl2?catalyzed de novo formation is confirmed by principal component analysis(PCA);their contributions at different conditions are then discussed.
作者
张梦玫
李晓东
陈彤
ZHANG Mengmei;LI Xiaodong;CHEN Tong(State Key Laboratory of Clean Energy Utilization,Institute for Thermal Power Engineering,Zhejiang University,Hangzhou 310027)
出处
《环境科学学报》
CAS
CSCD
北大核心
2019年第8期2735-2746,共12页
Acta Scientiae Circumstantiae
基金
国家重点研发计划战略性国际科技创新合作重点专项(No.2016YFE0202000)
关键词
氯化铜
模拟飞灰
二噁英
催化
指纹特性
异构体分布
copper chloride
model fly ash
polychlorinated dibenzo-p-dioxins(PCDD)and dibenzofurans(PCDF)
catalysis
signature or fingerprint
isomer distribution
