Vanadia/titania catalysts for gas phase partial toluene oxidation. Spectroscopic characterization and transient kinetics study

Formation of vanadia species during the calcination of ball milled mixt. of V2O5 with TiO2 was studied by Raman spectroscopy in situ and at ambient conditions. Calcination in air leads to fast (1-3 h) spreading of vanadia over TiO2 followed by a slower process giving a monolayer vanadia. The calcinated catalyst showed higher activity during toluene oxidn. than the uncalcinated one, but the selectivity towards C7-oxygenated products (benzaldehyde and HOBz) remains unchanged. The activity of the catalysts is ascribed to the formation of vanadia species in the monolayer. The details of the parallel-consecutive reaction scheme of toluene oxidn. are presented from steady-state and transient kinetics studies. Different O species seem to participate in the deep and partial oxidn. of toluene. Coke formation was obsd. during the reaction presenting an av. compn. C2nH1.1n. The amt. of coke on the catalyst was not dependent on the calcination step and the V content in the catalyst. Coke formation is responsible for the deactivation of the catalyst. [on SciFinder (R)]


Published in:
Catalysis Today, 57, 3-4, 231-239
Year:
2000
Keywords:
Note:
CAN 132:321600
22-7
Physical Organic Chemistry
Institute of Chemical Engineering,Swiss Federal Institute of Technology,Lausanne,Switz.
Journal
0920-5861
written in English.
1314-62-1 (Vanadium oxide (V2O5); 13463-67-7 (Titanium oxide (TiO2) Role: CAT (Catalyst use), PRP (Properties), USES (Uses) (vanadia/titania catalysts for gas phase partial toluene oxidn. Spectroscopic characterization and transient kinetics study); 65-85-0 (Benzoic acid); 100-52-7 (Benzaldehyde); 108-31-6 (Maleic anhydride) Role: FMU (Formation, unclassified), FORM (Formation, nonpreparative) (vanadia/titania catalysts for gas phase partial toluene oxidn. Spectroscopic characterization and transient kinetics study); 108-88-3 (Toluene) Role: PEP (Physical, engineering or chemical process), PRP (Properties), RCT (Reactant), PROC (Process), RACT (Reactant or reagent) (vanadia/titania catalysts for gas phase partial toluene oxidn. Spectroscopic characterization and transient kinetics study)
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