Kinetic isotope effect in the selective oxidation of methanol to formaldehyde over some molybdate catalysts

Journal Article · Thu Jul 01 04:00:00 EDT 1982 · J. Catal.; (United States)

DOI:https://doi.org/10.1016/0021-9517(82)90254-8· OSTI ID:6799767

Machiels, C J; Sleight, A W

Kinetic isotope effects were measured using fully deuterated methanol, CH/sub 3/OD, and CD/sub 3/OD. Four catalysts were tested: a commercial preparation containing a 3:1 molar ratio of MoO/sub 3/ and Fe/sub 2/(MoO/sub 4/)/sub 3/, pure MoO/sub 3/, pure Fe/sub 2/(MoO/sub 4/)/sub 3/, and FeMoO/sub 4/. Surface areas varied from 2.3 m/sup 2//g for MoO/sub 3/ to 6.1 m/sup 2//g for Fe(MoO/sub 4/)/sub 3/. 3 g of catalyst were used in a differential reactor with external recycle. Mass and heat transfer were rapid compared to the rate of the reaction. The feed gas contained 2 to 20% methanol, 5 to 40% oxygen, and the balance nitrogen. Differential rates were obtained under steady state conditions over a wide range of conversions. The rate constants were obtained by fitting the data to a rate equation of the power law. Results show that the rate-limiting step with all four catalysts is the abstraction of a hydrogen from the methyl group. This fact is confirmed by changes in product distribution. CH/sub 3/OH and CH/sub 3/OD yield identical product distributions, but with CD/sub 3/OD the selectivity to dimethyl ether increases by a factor of 4 to 6.

• Research Organization: E.I. du Pont de Nemours and Co., Wilmington, DE
• OSTI ID: 6799767
• Journal Information: J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 76:1; ISSN JCTLA
• Country of Publication: United States
• Language: English

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ALCOHOLS
ALDEHYDES
CATALYSTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
COMPARATIVE EVALUATIONS
DATA
DEUTERIUM
DEUTERIUM COMPOUNDS
ELEMENTS
ENERGY TRANSFER
ETHERS
EXPERIMENTAL DATA
FORMALDEHYDE
HEAT TRANSFER
HIGH TEMPERATURE
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
HYDROXY COMPOUNDS
INFORMATION
ISOTOPE EFFECTS
ISOTOPES
KINETICS
LIGHT NUCLEI
MASS TRANSFER
METHANOL
METHYL ETHER
NITROGEN
NONMETALS
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXIDATION
OXYGEN
QUANTITY RATIO
REACTION KINETICS
STABLE ISOTOPES
STEADY-STATE CONDITIONS
SURFACE AREA
SURFACE PROPERTIES
TEMPERATURE DEPENDENCE
YIELDS