Relationship of Crystals Shape, Aggregation Mode and Surface Purity in Catalytic Wet Peroxide Oxidation of Phenol in Dark with Titania Anatase Nanocrystals

A series of TiO₂ anatase materials with a thickness to width ratio of 0.22–0.62 in their primary nanocrystals, 1.03–1.27 nanocrystals aggregation ratio and 38–68% exposure of (001) facets were tested in phenol CWPO in a fixed-bed reactor in dark. Inactive oxyfluoride phase that covers the as-synthesized nanocrystals should be removed in order to get the highest catalytic activity. Catalytic activity was proportional to the value of surface area related to the exposed (001) facets at the TiO₂ nanocrystals surface excluding any synergistic effects between (001) and (101) facets in catalysis. The linear regression of experimental data for studied reaction revealed that the specific catalytic activity per 1 m² of (001) facets at the surface of TiO₂ nanocrystals is at least four times higher compared with that of (101) facets. This is in agreement with theoretical predictions attributing the catalytic activity to surface titanols as active sites and formation of titanols mainly at the surface of (001) facets due to dissociative adsorption of water. Graphical Abstract: [Figure not available: see fulltext.].