Experimental study of factors affecting Pt-TiO 2 thermal catalytic oxidation of formaldehyde

Abstract

TiO₂-supported precious metal photo- (PCO) and thermal catalytic oxidation (TCO) are new kind of formaldehyde degradation air cleaning methods, characterized to have low energy consumption for operation in air conditioning system and would produce no harmful by-products. In this study, Pt-TiO₂ thermal catalyst was prepared and its composition and pore structure was examined by X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET) methods. The impact of reaction temperature, air-flow rate and initial concentration of formaldehyde to the catalytic degradation effect was investigated. The largest relative change rate of the specific degradation rate was 0.49%/℃ within the temperature range from 70 to 120℃. Compared with other relevant studies, the reaction temperature was reduced and made the catalyst more suitable for air conditioning systems in respect to energy consumption. When the specific degradation rate was less than 1500 mg/(g.h), the catalytic reaction was dominated by the diffusion rate of formaldehyde molecules onto the catalyst surface, and both the air-flow rate and initial formaldehyde concentration caused proportional change of the specific degradation rate. The maximum catalytic capacity could be as high as 1800 mg/(g.h), but was hard to achieve by changing reaction conditions.