Langmuir-Hinshel-wood-type

A kinetic study carried out with a well-stirred reactor was reported by Cartlidge et al. [78,79], Temperatures below 420°C were used to avoid acrylic acid formation. At atmospheric pressure, the oxygen and propene concentrations were varied between 1 and 10, and 5 and 15%, respectively. Selectivities of 60—90% and a maximum acrolein yield of 28% were reported at 400° C. The kinetic results were fitted to a Langmuir—Hinshel-wood type of rate equation... 

However, simple kinetic models, especially of the Langmuir—Hinshel-wood type, can serve with advantage for correlation of experimental data in spite of simplifying assumptions which are necessary for their derivation. Experience shows that heterogeneous acid—base catalysis is the very field where they fit best. Their most frequent general form... 

The form of the resulting expression differs from the gas-phase reaction rate expressions due to the presence of a denominator representing the reduction in rate due to adsorption phenomena. The individual terms of this denominator respresent the distribution of the active sites among the possible surface complexes and vacancies. Expressions of this type are termed the Langmuir-Hinshel-wood-Hougen-Watson (LHHW) rate expressions in heterogeneous catalysis and Michaelis-Menten expressions in biocatalysis. 

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