Photocatalytic Synthesis of p-Anisaldehyde in a Mini Slurry-Bubble Reactor under Solar Light Irradiation

Dense photocatalyst slurry was employed for the synthesis of p‐anisaldehyde under solar light irradiation. An Fe‐modified rutile TiO 2 (Fe‐TiO 2, 34.5 m 2/g) photocatalyst was used as a visible‐light‐responsive photocatalyst. A conventional TiO 2 (P25, 35 m 2/g) photocatalyst was also examined as a reference catalyst. XRD patterns and diffuse reflectance spectra showed that Fe‐TiO 2 consists of 100 % rutile phase and absorbs more visible light compared to P25, respectively. The catalyst powder was suspended in an ethyl acetate solution of p‐methoxytoluene in the mini‐reactor, with oxygen bubbling, under a solar simulator, visible light, and UV LEDs. p‐anisaldehyde, as a reaction product, was analyzed by sampling using gas‐chromatograph. Regardless of the light source, Fe‐TiO 2 always outperformed P25 in terms of both generation rates (GR) of p‐anisaldehyde and energy requirements (ER). It was demonstrated that the highly dense Fe‐TiO 2 slurry was efficient for the synthesis under solar light owing to the small size of the reactor. The small amount of Pt and ZrO 2 cocatalysts significantly enhanced the GR under solar light. By adopting a visible light responsive Fe‐TiO 2 photocatalyst, the mini slurry‐bubble reactor under solar light achieved a high GR per catalyst mass (CM), which is one to two orders higher than that reported by most previous studies with high‐power lamps.