Abstract:

Titania supported vanadia catalyst exhibits the high activity for the selective oxidation of propylene to acetone. The rate for the formation of acetone at 463 K was determined to be 98 μmol g^-1 min^-1, corresponding to the TOF of 2×l0^-3 s^-1. Kinetic results show that the reaction exhibits the first order to propylene, zeroth order to oxygen and 0.5th order to water at 383-433 K. XRD, UV-visible spectra and oxygen chemisorption reveal that the highly dispersed polyvanadates are the main vanadium species on titania. FT-IR and microcalorimetric studies for NH₃ adsorption indicate that the polyvanadates on the surface of V₂O₅/TiO₂ catalyst produced the Brönsted acid sites with the initial heat of 104 kJ/mol. The initial heats for adsorption of propylene, water, isopropanol, acetone and oxygen on V₂O₅/TiO₂ catalyst are 104,88,53,106,and 416 kJ/mol,respectively.