Photocatalytic oxidation of methanol using titania-based fluidized beds

Experiments determined methanol removal and catalyst elutriation rates during photocatalytic oxidation (PCO) of fluidized and packed beds of various titania-based catalysts. The study developed elutriation-resistant catalysts in which TiO 2 was precipitated from solution (p-TiO 2 ), or was coated on an Al 2 O 3 support (TiO 2 /Al 2 O 3 ) and compared them to Degussa P-25 TiO 2 . Although Degussa P-25 TiO 2 oxidized methanol effectively, it elutriated at a rate that was two orders of magnitude greater than those of p-TiO 2 and TiO 2 /Al 2 O 3 . In addition, TiO 2 /Al 2 O 3 removed methanol at a significantly greater rate than did P-25, with p-TiO 2 being the least active. Fluidized beds produced greater PCO rates than did packed beds of P-25 and TiO 2 /Al 2 O 3 . Fluidization enhancers, such as vibration and incorporation of a static mixer, improved the performance of the P-25 fluidized bed, but did not change the effectiveness of TiO 2 /Al 2 O 3 or p-TiO 2 . The activity of TiO 2 /Al 2 O 3 decreased with increasing calcination temperature (over the temperature range 673–873 K). The optimum TiO 2 loading for TiO 2 /Al 2 O 3 was 30 wt.%.