Molybdate and tungstate catalysts for methanol oxidation
The most selective catalysts for the oxidation of methanol to formaldehyde are molybdates. In many commercial processes, a mixture of ferric molybdate and molybdenum trioxide is used. Ferric molybdate has often been reported to be the major catalytically active phase with the excess molybdenum trioxide added to improve the physical properties of the catalyst and to maintain an adequate molybdenum concentration under reactor conditions. In some cases, a synergistic effect is claimed, with maximum catalytic activity for a mixture with an Fe/Mo ratio of 1.7. Aging of a commercial catalyst has been studied using a variety of analytical techniques and it was concluded that deactivation can largely be accounted for by loss of molybdenum from the catalyst surface. In this laboratory, the mechanism of methanol oxidation over molybdate and tungstate catalysts has been studied using a variety of techniques. Steady state and pulse reactor studies using labeled reactants have established that methanol conversion to formaldehyde is a redox reaction with lattice oxygen being involved. A kinetic isotope effect has recently been reported and it shows that the rate limiting step in the reaction sequence is removal of a hydrogen from the methyl group. Fourier transform infrared studies have shown that a methoxy CH/sub 3/O group is a surface intermediate during the reaction and temperature programmed reaction studies have elucidated the nature of surface reactions and have allowed estimation of the number of catalytically active sites on powder surfaces.
- Research Organization:
- Central Research and Development Department, Experimental Station, E.I. du Pont de Nemours and Company, Wilmington, Delaware
- OSTI ID:
- 6646513
- Report Number(s):
- CONF-830814-
- Journal Information:
- Am. Chem. Soc., Div. Pet. Chem., Prepr.; (United States), Vol. 28:5; Conference: 186. national meeting of the American Chemical Society, Washington, DC, USA, 28 Aug 1983
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
FORMALDEHYDE
PRODUCTION
METHANOL
OXIDATION
MOLYBDENUM OXIDES
CATALYTIC EFFECTS
BENCH-SCALE EXPERIMENTS
CHEMICAL REACTION KINETICS
REDOX REACTIONS
TEMPERATURE EFFECTS
ALCOHOLS
ALDEHYDES
CHALCOGENIDES
CHEMICAL REACTIONS
HYDROXY COMPOUNDS
KINETICS
MOLYBDENUM COMPOUNDS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
REACTION KINETICS
TRANSITION ELEMENT COMPOUNDS
090210* - Alcohol Fuels- Properties- (1976-1989)
400301 - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)