Influence of oxygen and water content on the formation of polychlorinated organic by-products from catalytic degradation of 1,2-dichlorobenzene over a Pd/ZSM-5 catalyst

Na Li; Xin Xing; Jie Cheng; Zhongshen Zhang; Zhengping Hao

doi:10.1016/j.jhazmat.2020.123952

Influence of oxygen and water content on the formation of polychlorinated organic by-products from catalytic degradation of 1,2-dichlorobenzene over a Pd/ZSM-5 catalyst

J Hazard Mater. 2021 Feb 5:403:123952. doi: 10.1016/j.jhazmat.2020.123952. Epub 2020 Sep 12.

Authors

Na Li¹, Xin Xing¹, Jie Cheng², Zhongshen Zhang³, Zhengping Hao¹

Affiliations

¹ National Engineering Laboratory for VOCs Pollution Control Material & Technology, Research Center for Environmental Material and Pollution Control Technology, University of Chinese Academy of Sciences, Beijing 101408, PR China; Key Laboratory of Environmental Nanotechnology and Health Effects, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China.
² National Engineering Laboratory for VOCs Pollution Control Material & Technology, Research Center for Environmental Material and Pollution Control Technology, University of Chinese Academy of Sciences, Beijing 101408, PR China. Electronic address: jiecheng@ucas.ac.cn.
³ National Engineering Laboratory for VOCs Pollution Control Material & Technology, Research Center for Environmental Material and Pollution Control Technology, University of Chinese Academy of Sciences, Beijing 101408, PR China.

PMID: 33264996
DOI: 10.1016/j.jhazmat.2020.123952

Abstract

Understanding the generation and influence mechanism of polychlorinated organic by-products during the catalytic degradation of chlorinated volatile organic compounds (CVOCs) is essential to the safe and environmentally friendly treatment of those pollutants. In this study, a systematic investigation of the catalytic oxidation of 1,2-dichlorobenzene (1,2-DCB) was conducted using various oxygen and water contents over a Pd/ZSM-5(25) catalyst. It was found that decreasing the oxygen content and increasing the water content resulted in the improvement of the 1,2-DCB catalytic activity, while the amount and variety of polychlorinated organic by-products decreased. More importantly, when water was the sole oxidant, the Pd/ZSM-5(25) catalyst also demonstrated high activity towards 1,2-DCB catalytic degradation. Only chlorobenzene and 1,3-dichlorobenzene were detected as by-products. X-ray photoelectron spectra (XPS) and UV-vis DRS spectra results indicated that the polychlorinated organic by-products were suppressed mainly due to inhibition of the chlorination of the palladium species by regulating the oxygen and water content in the reaction atmosphere. Similar surface species were formed under aerobic and anaerobic atmospheres via the study of the in situ FTIR spectra. We therefore proposed that 1,2-DCB undergoes similar catalytic degradation reaction mechanisms under both aerobic and anaerobic conditions.

Keywords: 1,2-Dichlorobenzene; Oxygen content; Polychlorinated organic by-products; Reaction mechanism; Water content.

Publication types

Research Support, Non-U.S. Gov't