Regeneration of High Silica Zeolites via Advanced Oxidation Processes—A Preliminary Study About Adsorbent Reactivity Toward Ozone

Abstract

Aiming at regenerating adsorbents, the reactivity toward ozone of two high silica zeolites (HSZ), a dealuminated faujasite Y (Fau Y) and a silicalite (Sil Z), was investigated. In case of Fau Y, no physical adsorption occurred but a total degradation of ozone. This phenomenon was attributed to an active sites-role of silanol groups (SiOH), mainly developed by the dealumination step. In contrast, the ozone adsorption in the smaller channels of Sil Z was important (about 17 mmol g−1), but when a certain local concentration of ozone was reached, the ozone degradation became significant and increased up to 100%. The ozonated zeolites were regenerated in an oven. Whereas the regeneration was total at 773K, a treatment at 500K seemed insufficient since a co-adsorption phenomenon was observed with suspected nitrous oxides (NO2) as a product of ambient nitrogen oxidation. Whereas the Fau Y was not affected at all by ozonation, the adsorption capacities of Sil Z zeolite were enhanced, and it exhibited a higher selectivity for polar compound. This was attributed to a surface modification, by highly reactive species generated during molecular ozone decomposition