Natural zeolite reactivity towards ozone: the role of acid surface sites

ALEJANDRO, S.; VALDÉS, H.; ZAROR, C.
Journal of Advanced Oxidation Technologies 14:2 (2011) 182-189.

Abstract

Ground-level ozone is an air pollutant which interferes with plant photosynthesis, stunts overall growth of some plant species, and harms animal respiratory systems. Activated carbon, synthetic zeolites, metal oxides and noble metals have been used as catalysts to destroy ozone. However, the high costs of these materials impair their application at full-scale. Low cost natural zeolites could be an interesting option for ozone elimination. In this work, the influence of Chilean natural zeolite chemical surface properties on gaseous ozone removal was evaluated. Chemical modifications of Chilean natural zeolite showed the role of acid surface sites and the Si/Al ratio on gaseous ozone abatement. Samples were characterised by nitrogen adsorption at 77 K, elemental analyses, X-ray fluorescence (XRF), temperature-programmed desorption (TPD), and hygroscopic analyses. The influence of air humidity on gaseous ozone removal using natural and modified zeolite samples was also evaluated. The results showed that lower Si/Al ratio corresponds to a higher density of Lewis acid sites. It was found that increasing the zeolite surface area does not improve gaseous ozone removal. The conversion of Brønsted acid sites into Lewis acid sites at 823 K led to an increase on ozone removal.

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