Indoor Formaldehyde Removal by Thermal Catalyst: Kinetic Characteristics, Key Parameters, and Temperature Influence

Abstract

Thermal catalytic oxidation (TCO) technology can continuously degrade formaldehyde at room temperature without added energy. However, there is very little knowledge on the TCO kinetic reaction mechanism, which is necessary in developing such air cleaners and in comparison with other air cleaning techniques. This paper addresses the problem of a novel TCO catalyst, Pt/MnO(x)-CeO(2). The experiments measuring the outlet concentrations of formaldehyde and other possible byproducts were conducted at temperatures of 25, 40, 60, 100, and 180 °C and at a series of inlet formaldehyde concentrations (280-3000 ppb). To measure the concentrations precisely and real timely, proton transfer reaction-mass spectrometry (PTR-MS) was used. We found the following from the experimental results: (1) no byproducts were detected; (2) the bimolecular L-H kinetic model best described the catalytic reaction rate; (3) the activation energy of the oxidation was about 25.8 kJ mol(-1); (4) TCO is most energy efficient at room temperature without auxiliary heating; (5) compared with photocatalytic oxidation (PCO) which needs ultraviolet light radiation, the reaction area of TCO can be much larger for a given volume so that TCO can perform much better not only in formaldehyde removal efficiency but also in energy saving.