Abstract

Volatile organic compounds (VOCs) constitute the vast majority of indoor air contaminants. In design of ultraviolet photo-catalytic oxidation (UV-PCO) air cleaner system, the focus must be in selecting an appropriate catalyst that can transform all contaminants to harmless gases. Some produced contaminants may promote or inhibit the photocatalytic reactions, or even lead to deactivation of the catalyst. The PCO reactions of two classes of VOCs, light alcohols and alkanes (C5-C10) were studied with different types of nano titanium dioxide catalysts. The influence of relative humidity on oxidation rate of tested VOCs was discussed in detail to establish ideal operational conditions for the selected group of VOCs.
A series of laboratory experiments was conducted with a pilot four-parallel duct system setup to test the VOCs in very low concentration levels which represents a typical indoor air environment. The experiments were carried out with different types of nano TiO2 catalysts with UV lamps. A new type of titanium dioxide catalyst was specifically developed for this study to enhance the efficiency of PCO system. A systematic method was used to develop and test the synthesized photocatalysts, which helped to improve the overall performance of test system. The performance of different catalysts was studied at different humidity conditions and different VOCs concentrations.
The research objective was to develop a correlation between the PCO kinetic rate constants and physical characteristics of indoor VOCs. These correlations may be employed to eliminate the need of further experiments with every individual VOCs and they also could facilitate the design process of future PCO air cleaner. The physical characteristics of VOCs were used to estimate the performance of the PCO catalysts in a steady-state environmental test condition. The photocatalytic removal efficiency of VOCs and formation of intermediates and byproducts were studied with and without ozone generation UV lamps.