Catalytic decomposition of gaseous 1, 2-dichlorobenzene over CuOx/TiO2 and CuOx/TiO2-CNTs catalysts: Mechanism and PCDD/Fs formation. (February 2016)

• Record Type: Journal Article
• Authors: Wang, Qiu-lin; Huang, Qun-xing; Wu, Hui-fan; Lu, Sheng-yong; Wu, Hai-long; Li, Xiao-dong; Yan, Jian-hua
• Is Part Of: Chemosphere. Volume 144(2016)
• Page Start: 2343
• Page End: 2350
• Publication Date: 2016-02
• Subjects: Composite catalyst -- Carbon nanotubes -- Catalytic oxidation -- Mechanism -- PCDD/Fs formation; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2015.10.097
• Languages: English
• ISSNs: 0045-6535

Abstract

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). Graphical abstract: Highlights: Catalytic decomposition of gaseous 1, 2-DCBz over CuOx/TiO2 -CNTs composite catalysts. The catalytic activity can be promoted when CNTs is introduced. Correlation between catalyst structure and catalytic activity is revealed. Catalytic oxidation mechanism is discussed based on verifying the role of oxygen in the system. PCDD/Fs generation during 1, 2-DCBz catalytic oxidation is also confirmed and discussed.