Catalytic combustion of vinyl chloride emissions over Co 3 O 4 catalysts with different crystallite sizes
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Catalytic combustion of vinyl chloride emissions over Co3O4 catalysts with different crystallite sizes Wen-Chao Hua, Ming-Qi Li, Yang-Long Guo* , Guang-Tao Chai, Hao Liu, Yun Guo, Li Wang, Wang-Cheng Zhan*
Received: 15 July 2019 / Revised: 23 September 2019 / Accepted: 28 June 2020 Ó The Nonferrous Metals Society of China and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract A series of Co3O4 catalysts was prepared by ammonia (Co-AP) and oxalate (Co-OP) precipitation, sol– gel (Co-SG), and urea hydrothermal (Co-UH) methods, and their physicochemical properties were characterised by numerous techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen sorption, X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction of H2 (H2-TPR), temperature-programmed desorption of O2 (O2-TPD), and temperature-programmed desorption of NH3 (NH3-TPD). The catalytic activity of each catalyst was estimated for the catalytic combustion of vinyl chloride (VC) emissions. The crystallite size of the Co3O4 catalyst was found to be well correlated with the amounts of surface-adsorbed oxygen species and number of acid sites on the catalyst surface, and consequently, determined several physicochemical properties of the catalyst. Of the catalysts studied here, the Co-AP catalyst exhibits the smallest crystallite size, which increases the specific surface area and the concentration of Co2? on the catalyst surface. This, in turn, enhances the redox property, oxygen mobility, and the number of acid sites associated with the Co-AP catalyst. In fact, the Co-AP catalyst exhibits the best catalytic activity for VC combustion at 360 °C and does not produce any chlorinated by-products.
W.-C. Hua, M.-Q. Li, Y.-L. Guo*, G.-T. Chai, H. Liu, Y. Guo, L. Wang, W.-C. Zhan* Key Laboratory for Advanced Materials, Research Institute of Industrial Catalysis, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China e-mail: [email protected] W.-C. Zhan e-mail: [email protected]
Keywords Catalytic combustion; Vinyl chloride; Cobalt oxides; Crystallite size; Preparation methods
1 Introduction Chlorinated volatile organic compounds (CVOCs) are typical volatile organic compounds (VOCs) produced in industrial processes, which not only have harmful effects on human health, but also cause significant environmental problems such as photochemical smog and ozone depletion, among others [1]. In fact, CVOCs have been listed as one of the 17 most highly toxic chemicals by the US Environmental Protection Agency and have been ranked as the most harmful gas pollutants, as declared by the European Community. CVOC pollutants mainly include chlorinated aromatic hydrocarbons, chlorinated alkanes, and chlorinated olefins, among which vinyl chloride (VC) is one of the pollutants associated with the highest emissions because of the mass production of polyvinyl chloride. Therefore, it
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