Challenges of TiO₂-Based Photooxidation of Volatile Organic Compounds: Designing, Coating, and Regenerating Catalyst

Abstract

A TiO 2 -based photocatalytic oxidation study of volatile organic compounds (VOCs: benzene, toluene, ethylbenzene, and xylenes) requiring close monitoring of the catalyst coating, its deactivation, and regeneration was undertaken. For all experiments, the effectiveness of sol−gel coating of nanosized TiO 2 particles (on a glass cylindrical reactor) in terms of the surface morphology, film thickness, and band-gap energy was ensured for obtaining a consistent reactor performance. The estimated VOC degradation rate constants (range of 1.16 ± 0.06−1.79 ± 0.05 min −1 m −2 ) were comparable or higher than those reported in the literature. Reduction of the degradation rates [48% (o-xylene) and 59% (toluene) over a 13 h operation period] with successive deterioration of the catalyst surface appeared to be a major challenge both for design of the reactor and for its long-term operation. A set of definite suggestions has been made for design criteria (degradation rate) and the frequency and method of catalyst regeneration for long-term field operations.

Promoting ring-opening efficiency for suppressing toxic intermediates during photocatalytic toluene degradation via surface oxygen vacancies

“…Volatile organic compounds (VOCs), as a kind of toxic substance in air, could pose serious damage to human health [1,2]. As one of typical VOCs, toluene is utilized as an organic solvent in adhesives and paints in the past few years and is likely to be emitted from building material to indoor environment.…”

Reactive magnetron sputtering deposition of bismuth tungstate onto titania nanoparticles for enhancing visible light photocatalytic activity

“…Consequently, the capability of photocatalytic materials in VOC destruction is often used for testing their efficiency as photocatalysts. Of the model VOCs pollutants, photocatalytic materials are most frequently tested for their ability to destruct acetone [1][2][3][4][5], formaldehyde [6], methanol [1,7], benzene [5,8], phenol [9,10] and toluene [5,9,11,12]. Of the known photocatalytic materials, titanium dioxide, or titania, in anatase form is typically the photocatalyst of choice for various environmental remediation processes, due to its low cost, chemical stability and low toxicity.…”

Efficient photocatalytic oxidation of methane over β-Ga2O3/activated carbon composites

“…Heterogeneous photocatalysis is regarded as an ideal technology for solving the urgent energy and environmental issues, [11][12][13] especially in removing various gaseous pollutants at ambient pressure and temperature. 14,15 Previous studies have also indicated CH 4 molecules can be activated and subsequently oxidized via TiO 2 photocatalytic technology, 16,17 however, the efficiency of CH 4 photo-oxidation remains notoriously low. Adsorption and photoreaction are two successively key steps, which are generally interactional during the heterogeneous photocatalytic process.…”