Catalytic Ozonation of Toluene over Acidic Surface Transformed Natural Zeolite: A Dual-Site Reaction Mechanism and Kinetic Approach

Abstract

Volatile organic compounds (VOCs) are responsible for damage to health due to their carcinogenic effects. Catalytic ozonation using zeolite appears as a valuable process to eliminate VOCs from industrial emissions at room temperature. For full-scale application of this new abatement technology, an intrinsic reaction rate equation is needed for an effective process design and scale-up. Results obtained here provide a mechanistic approach during the initial stage of catalytic ozonation of toluene using an acidic surface transformed natural zeolite. In particular, the contribution of Lewis and Brønsted acid sites on the surface reaction mechanism and overall kinetic rate are identified through experimental data. The least-squares non-linear regression method allows the rate-determining step to be established, following a Langmuir–Hinshelwood surface reaction approximation. Experimental evidence suggest that ozone is adsorbed and decomposed at Lewis acid sites, forming active atomic oxygen that leads to the oxidation of adsorbed toluene at Brønsted acid sites.

Preparation of MnOx–Al2O3 aerogels and synergistic catalytic oxidation of toluene via ozone

“…10(a) and Table S2 (ESI†) that the reaction under MnO x –Al 2 O 3 aerogel was more in line with the L–H d model ( r 2 = 0.976, higher than L–H s ), which was consistent with the result of related reports. 53,54 It was verified that the oxidation rate of toluene was not solely caused by the single site (MnO x ) and ozone, but rather depended on the interaction of different types and a certain number of adjacent active sites, which provided support for the contribution of high acidity on MnO x –Al 2 O 3 aerogel to its excellent performance.…”

“…The calculation formulas of the toluene removal rate, ozone digestion rate, CO 2 selectivity, steady-state reaction rate, Langmuir–Hinshelwood single-site model, 53 and Langmuir–Hinshelwood dual-site model 54 are as follows:…”