Continuous Production of N–F-Codoped Titanium Oxide Photocatalyst Powders via Drip Pyrolysis in a Fluidized Bed under Reduction Conditions

This study investigates drip pyrolysis in a fluidized bed (DPFB) applied to the continuous production of anatase-type N–F-codoped titanium oxide photocatalysts with oxygen vacancy under a reducing atmosphere for the development of a more compact reactor with fewer operating steps. The effects of bed temperature, precursor sol concentration and superficial gas velocity on the particle properties of the product powder and the photocatalytic activity of gaseous acetaldehyde degradation have been investigated. Although the photocatalysts produced by DPFB showed very small N-doping as compared to F-doping, they showed higher absorbance in both visible and ultraviolet regions than those by an electric furnace (EF). The surface atomic ratio of F to Ti increased with increasing the precursor sol concentration and superficial gas velocity. The BET surface area of product photocatalyst sample prepared at 773 K by DPFB was three times larger than that by an electric furnace, and its photocatalytic activity was higher than any other photocatalysts prepared in this study.