| Summary: | It is shown that the potassium polytitanate powder (PPT) synthesized at 500 °C via the treatment of powdered TiO<sub>2</sub> (rutile) in molten mixtures of KOH and KNO<sub>3</sub> is a cheap and effective catalyst of H<sub>2</sub>O<sub>2</sub> chemical decomposition in aqueous solutions. At the same time, the PPT catalytic activity strongly depends on the [TiO<sub>2</sub>]:[KOH]:[KNO<sub>3</sub>] weight ratio in the mixture used for the synthesis, increasing with [KNO<sub>3</sub>] in the order of PPT (30:30:40) < PPT (30:50:20) < PPT (30:70:0). The obtained results are explained by increased [Ti<sup>3+</sup>] in the PPT structure (XPS data), which is grown in this order from 0 to 4.0 and 21.9 at.%, respectively, due to the reduced oxidation activity of the melt used for PPT synthesis. The mechanism of the autocatalytic process taking place in the PPT-H<sub>2</sub>O<sub>2</sub>-H<sub>2</sub>O system is analyzed. Taking into account the data of FT-IR spectroscopy, it is assumed that the increased catalytic activity of the investigated materials is related to the increased surface concentration of the Ti<sup>4+</sup>-O(H)-Ti<sup>4+</sup> groups, formed from the Ti<sup>3+</sup>-O(H<sub>3</sub>O<sup>+</sup>)-Ti<sup>4+</sup> clusters and further transformed into Ti-O-O-H catalytic centers. Some possible applications of the PPT-H<sub>2</sub>O<sub>2</sub>-H<sub>2</sub>O catalytic system, including the oxidation processes of green chemistry and photo-catalysis, are discussed.
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