Resumen:
Quartz capillaries were assessed as multiphase photocatalytic reactors. The tested reaction was the
salicylic acid (2-dihidroxibenzoic acid) oxidation. The catalyst (TiO2) was either in slurry or immobilized
by sol-gel method onto the capillary wall. All experiments were conducted under oxygen flow and Taylor
flow hydrodynamic regime. TiO2 Films were characterized by Raman spectroscopy, diffuse reflectance
UV-Vis spectroscopy and scanning electronic microscopy. The effect of two synthesis variables was
established. These variables were volumetric ratio of precursors solutions (i-PrO:2-propanol:nitric acid)
and number of capillary coating cycles. These variables were found to importantly affect film
homogeneity and oxidation rate. The highest initial reaction rate (106.32x10-6 mol dm-3s-1) was obtained
when using the TiO2 as film prepared with a precursors volumetric ratio of 1:15:1 and with two coating
cycles. For comparison purposes, the same oxidation process was conducted in a stirred reactor and it was
found that the reaction rate value is diminished by almost four times in comparison with that obtained
under Taylor flow in the capillary reactor. Selectivity was found to be dependant on the type of catalyst
addition, slurry or immobilized. Catalytic films employed in this non-common reaction system were
2
reused three times losing less than 10% of their photocatalytic activity. The photonic efficiency was
found to be two orders of magnitude higher in the coated capillary reactor than in the slurry stirred reactor.
