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 TiO2 was precipitated from solution (p-TiO2), or was coated on an Al2O3 support (TiO2/Al2O3) and compared them to Degussa P-25 TiO2. Although Degussa P-25 TiO2 oxidized methanol effectively, it elutriated at a rate that was two orders of magnitude greater than those of p-TiO2 and TiO2/Al2O3. In addition, TiO2/Al2O3 removed methanol at a significantly greater rate than did P-25, with p-TiO2 being the least active. Fluidized beds produced greater PCO rates than did packed beds of P-25 and TiO2/Al2O3. 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 TiO2/Al2O3 or p-TiO2. The activity of TiO2/Al2O3 decreased with increasing calcination temperature (over the temperature range 673–873 K). The optimum TiO2 loading for TiO2/Al2O3 was 30 wt.%.