Titanium dioxide photocatalyst deactivation by gas-phase oxidation of polymethylsiloxane (PDMS) and silicone sealant off-gas in a recirculating batch reactor

Indoor air quality is one of the most promising applications of photocatalytic oxidation. Rapid deactivation of the photocatalyst by ubiquitous indoor air pollutants would diminish the utility of photocatalytic technology. We have studied deactivation of TiO2 photocatalyst by oxidation of PolyDiMethylSiloxane (PDMS) and silicone sealant off-gas in a recirculating batch reactor.; The oxidation of the Si-containing vapor was monitored with an FTIR equipped with a gas cell. Subsequent to each incremental exposure, a hexane oxidation reaction was performed to track the TiO2 catalyst activity. In this manner, loss of catalyst activity was quantitatively related to oxidation of Si-containing organic molecules. The exposures were repeated until a substantial deactivation was achieved.; Surface science techniques were used to view the topography of the catalyst and to identify the elements causing the deactivation.