Catalytic oxidation of propylene--7. Use of temperature programmed reoxidation to characterize. gamma. -bismuth molybdate

Journal Article · Sat Mar 01 04:00:00 EST 1980 · J. Catal.; (United States)

DOI:https://doi.org/10.1016/0021-9517(80)90417-0· OSTI ID:6199909

Uda, T; Lin, T T; Keulks, G W

Temperature-programed reoxidation of propylene-reduced ..gamma..-Bi/sub 2/MoO/sub 6/ revealed a low-temperature peak (LTP) at 158/sup 0/C and a high-temperature peak (HTP) at 340/sup 0/C. Auger spectroscopy and X-ray diffraction of reduced and partially or completely reoxidized bismuth molybdate showed that at the LTP, molybdenum(IV) is oxidized to molybdenum(VI) and bismuth, from the metallic state to an oxidation state between zero and three, and that the HTP is associated with the complete oxidation of bismuth to bismuth(III). Activity tests for propylene oxidation showed lower acrolein formation on the catalyst, on which only the LTP was reoxidized than on catalysts on which both peaks were reoxidized. The reoxidation kinetics of the catalyst under conditions corresponding to the LTP showed an activation energy of 22.9 kcal/mole below 170/sup 0/C and near zero above 170/sup 0/C; the break in the Arrhenius plot of reoxidation of the catalyst under conditions corresponding to the HTP was at 400/sup 0/C, with activation energies of 46 kcal/mole at lower and near zero at higher temperatures. Propylene oxidation was apparently rate-limited by the HTP reoxidation process below 400/sup 0/C and by allylic hydrogen abstraction above 400/sup 0/C.

• Research Organization: Univ. of Wisconsin, Milwaukee
• OSTI ID: 6199909
• Journal Information: J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 62:1; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ACROLEIN
ACTIVATION ENERGY
ALDEHYDES
ALKENES
ARRHENIUS EQUATION
AUGER ELECTRON SPECTROSCOPY
BISMUTH
CATALYSTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COHERENT SCATTERING
DATA
DIFFRACTION
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY
EQUATIONS
EXPERIMENTAL DATA
HIGH TEMPERATURE
HYDROCARBONS
HYDROGEN
INFORMATION
KINETICS
METALS
MOLYBDATES
MOLYBDENUM
MOLYBDENUM COMPOUNDS
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDATION
OXYGEN COMPOUNDS
PROPYLENE
REACTION KINETICS
REFRACTORY METAL COMPOUNDS
SCATTERING
SPECTROSCOPY
STRUCTURAL CHEMICAL ANALYSIS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
X-RAY DIFFRACTION