title: Catalytic decomposition of gaseous 1,2-dichlorobenzene over CuOx/TiO₂ and CuOx/TiO₂-CNTs catalysts: Mechanism and PCDD/Fs formation.
abstract: Gaseous 1,2-dichlorobenzene (1,2-DCBz) was catalytically decomposed in a fixed-bed catalytic reactor using composite copper-based titanium oxide (CuOx/TiO2) catalysts with different copper ratios. Carbon nanotubes (CNTs) were introduced to produce novel CuOx/TiO2-CNTs catalysts by the sol-gel method. The catalytic performances of CuOx/TiO2 and CuOx/TiO2-CNTs on 1,2-DCBz oxidative destruction under different temperatures (150-350 °C) were experimentally examined and the correlation between catalyst structure and catalytic activity was characterized and the role of oxygen in catalytic reaction was discussed. Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) generation during 1,2-DCBz catalytic oxidation by CuOx/TiO2-CNTs composite catalyst was also examined. Results indicate that the 1,2-DCBz destruction/removal efficiencies of CuOx (4 wt%)/TiO2 catalyst at 150 °C and 350 °C with a GHSV of 3400 h(-1) are 59% and 94% respectively and low-temperature (150 °C) catalytic activity of CuOx/TiO2 on 1,2-DCBz oxidation can be improved from 59 to 77% when CNTs are introduced. Furthermore, oxygen either in catalyst or from reaction atmosphere is indispensible in reaction. The former is offered to activate and oxidize the 1,2-DCBz adsorbed on catalyst, thus can be generally consumed during reaction and the oxygen content in catalyst is observed lost from 39.9 to 35.0 wt% after reacting under inert atmosphere; the latter may replenish the vacancy in catalyst created by the consumed oxygen thus extends the catalyst life and raises the destruction/removal efficiency. The introduction of CNTs also increases the Cu(2+)/Cu(+) ratio, chemisorbed oxygen concentration and surface lattice oxygen binding energy which are closely related with catalytic activity. PCDD/Fs is confirmed to be formed when 1,2-DCBz catalytically oxidized by CuOx/TiO2-CNTs composite catalyst with sufficient oxygen (21%), proper temperature (350 °C) and high concentration of 1,2-DCBz feed (120 ppm).
authors.affiliation: State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering of Zhejiang University, Hangzhou 310027, China; School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
authors.forename: Qiu-lin
authors.initials: QL
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering of Zhejiang University, Hangzhou 310027, China. Electronic address: hqx@zju.edu.cn.
authors.forename: Qun-xing
authors.initials: QX
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering of Zhejiang University, Hangzhou 310027, China.
authors.forename: Hui-fan
authors.initials: HF
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering of Zhejiang University, Hangzhou 310027, China.
authors.forename: Sheng-yong
authors.initials: SY
authors.lastname: Lu
authors.affiliation: Zhoushan Environmental Protection Bureau, Zhoushan 316000, China.
authors.forename: Hai-long
authors.initials: HL
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering of Zhejiang University, Hangzhou 310027, China.
authors.forename: Xiao-dong
authors.initials: XD
authors.lastname: Li
authors.affiliation: State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering of Zhejiang University, Hangzhou 310027, China.
authors.forename: Jian-hua
authors.initials: JH
authors.lastname: Yan
mesh_terms: D000327:Adsorption; D001572:Benzofurans / Q000737:chemistry*; D002384:Catalysis; D002722:Chlorobenzenes / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D000072338:Dibenzofurans, Polychlorinated; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010084:Oxidation-Reduction; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000737:chemistry; D013696:Temperature; D014025:Titanium / Q000737:chemistry*
chemical_list: D001572:Benzofurans; D002722:Chlorobenzenes; D000072338:Dibenzofurans, Polychlorinated; D037742:Nanotubes, Carbon; D000072317:Polychlorinated Dibenzodioxins; C009495:titanium dioxide; C004726:2-dichlorobenzene; D003300:Copper; D014025:Titanium
keywords: Carbon nanotubes; Catalytic oxidation; Composite catalyst; Mechanism; PCDD/Fs formation