Catalytic Decomposition of H 2 O 2 in the Aqueous Dispersions of the Potassium Polytitanates Produced in Different Conditions of Molten Salt Synthesis.

It is shown that the potassium polytitanate powder (PPT) synthesized at 500 °C via the treatment of powdered TiO 2 (rutile) in molten mixtures of KOH and KNO 3 is a cheap and effective catalyst of H 2 O 2 chemical decomposition in aqueous solutions. At the same time, the PPT catalytic activity strongly depends on the [TiO 2 ]:[KOH]:[KNO 3 ] weight ratio in the mixture used for the synthesis, increasing with [KNO 3 ] in the order of PPT (30:30:40) < PPT (30:50:20) < PPT (30:70:0). The obtained results are explained by increased [Ti 3+ ] 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 2 O 2 -H 2 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 4+ -O(H)-Ti 4+ groups, formed from the Ti 3+ -O(H 3 O + )-Ti 4+ clusters and further transformed into Ti-O-O-H catalytic centers. Some possible applications of the PPT-H 2 O 2 -H 2 O catalytic system, including the oxidation processes of green chemistry and photo-catalysis, are discussed.