Modified-TiO2 Photocatalyst Supported on β-SiC Foams for the Elimination of Gaseous Diethyl Sulfide as an Analog for Chemical Warfare Agent: Towards the Development of a Photoreactor Prototype

In the context of the increase in chemical threat due to warfare agents, the development of efficient methods for destruction of Chemical Warfare Agents (CWAs) are of first importance both for civilian and military purposes. Amongst possible methods for destruction of CWAs, photocatalytic oxidation is an alternative one. The present paper reports on the preparation of Ta and Sn doped TiO2 photocatalysts immobilized on beta-SiC foams for the elimination of diethyl sulfide (DES) used as a model molecule mimicking Yperite (Mustard Gas) in gaseous phase. Photo-oxidation efficiency of doped TiO2 catalyst has been compared with TiO2-P25. Here, we demonstrate that the Sn doped-TiO2 with a Polyethylene glycol (PEG)/TiO2 ratio of 7 exhibits the best initial activity (up to 90%) but is deactivates more quickly than Ta doped-TiO2 (40% after 800 min). The activity of the catalysts is strongly influenced by the adsorption properties of the support, as beta-SiC foams adsorb DES and other sulfur compounds. This adsorption makes it possible to limit the poisoning of the catalysts and to maintain an acceptable conversion rate even after ten hours under continuous DES flow. Washing with NaOH completely regenerates the catalyst after a firs treatment and even seems to wash it by removing impurities initially present on the foams.

Automated summary

This study investigated the efficiency of Ta and Sn doped TiO2 photocatalysts for the elimination of diethyl sulfide (DES) and compared their photo-oxidation efficiency with TiO2-P25. Results showed that Sn-doped TiO2 exhibited higher initial activity but deactivated faster, while Ta-doped TiO2 had slower deactivation rate. The adsorption properties of the beta-SiC foams significantly influenced the activity of the catalysts.