Two different reactions occur between CCl4 and TiO2. At moderate temperature, the nature of the superficial reaction strongly depends on the hydration state of the solid. On a dry titanium dioxide, CCl4 chemisorption on two bridges Ti-O-Ti gives a carbonyl complex detected by infrared spectroscopy. The reaction which follows from destruction of this complex proceeds by exchange of two superficial oxygen atoms for four chlorine atoms, with formation of gaseous CO2. Strongly oxidizing Ti4+ ions, with high electron accepting properties, are created through the elimination of superficial oxygen atoms. On hydrated titanium dioxide, these reactions are followed by the formation of HCl which generates hydronium ions. Results obtained on TiO2 and γ alumina point out the high reactivity towards CCl4 of superficial oxygen atoms, compared to hydroxyl groups. Reticular reaction, which starts at 150°, is a proof of the relatively high mobility of the oxygen in the anatase lattice.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry