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Catalysts 2018, 8(5), 211; https://doi.org/10.3390/catal8050211

Catalytic Ozonation of Toluene Using Chilean Natural Zeolite: The Key Role of Brønsted and Lewis Acid Sites

1
Nanomaterials and Catalysts for Sustainable Processes (NanoCatpPS), Wood Engineering Department, Faculty of Engineering, Universidad del Bío-Bío (UBB), 4030000 Concepción, Chile
2
Laboratorio de Tecnologías Limpias, Facultad de Ingeniería, Universidad Católica de la Santísima Concepción, 4030000 Concepción, Chile
3
Laboratoire de Génie Chimique, Université de Toulouse, CNRS, INPT, UPS, F-31030 Toulouse, France
4
Departamento de Ingeniería Química, Facultad de Ingeniería, Universidad de Concepción, 4030000 Concepción, Chile
*
Authors to whom correspondence should be addressed.
Received: 3 April 2018 / Revised: 24 April 2018 / Accepted: 2 May 2018 / Published: 17 May 2018
(This article belongs to the Special Issue Catalytic Oxidation in Environmental Protection)
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Abstract

The influence of surface physical-chemical characteristics of Chilean natural zeolite on the catalytic ozonation of toluene is presented in this article. Surface characteristics of natural zeolite were modified by acid treatment with hydrochloric acid and ion-exchange with ammonium sulphate. Prior to catalytic ozonation assays, natural and chemically modified zeolite samples were thermally treated at 623 and 823 K in order to enhance Brønsted and Lewis acid sites formation, respectively. Natural and modified zeolite samples were characterised by N2 adsorption at 77 K, elemental analysis, X-ray fluorescence, and Fourier transform infrared (FTIR) spectroscopy, using pyridine as a probe molecule. The highest values of the reaction rate of toluene oxidation were observed when NH4Z1 and 2NH4Z1 zeolite samples were used. Those samples registered the highest density values of Lewis acid sites compared to other samples used here. Results indicate that the presence of strong Lewis acid sites at the 2NH4Z1 zeolite surface causes an increase in the reaction rate of toluene oxidation, confirming the role of Lewis acid sites during the catalytic ozonation of toluene at room temperature. Lewis acid sites decompose gaseous ozone into atomic oxygen, which reacts with the adsorbed toluene at Brønsted acid sites. On the other hand, no significant contribution of Brønsted acid sites on the reaction rate was registered when NH4Z1 and 2NH4Z1 zeolite samples were used. View Full-Text
Keywords: Brønsted acid sites; catalytic ozonation; Chilean natural zeolite; Lewis acid sites; toluene Brønsted acid sites; catalytic ozonation; Chilean natural zeolite; Lewis acid sites; toluene
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Alejandro-Martín, S.; Valdés, H.; Manero, M.-H.; Zaror, C.A. Catalytic Ozonation of Toluene Using Chilean Natural Zeolite: The Key Role of Brønsted and Lewis Acid Sites. Catalysts 2018, 8, 211.

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