(629g) Kinetic Modeling of Ethanol Oligomerization over Calcium Hydroxyapatite
A kinetic model has been developed within a MATLAB framework which allows for the modeling of over 70 species which may participate in over 150 reactions. Rate expressions were developed for alcohol dehydration to mono-alkenes, Guerbet coupling to higher alcohols, and Lebedev condensation to dienes based on prior literature and our own findings. Reactions with various feed mixtures allow for the fitting of kinetic parameters include rate constants and adsorption constants. Our findings show that water inhibition can fully account for the declining rates observed with increasing conversion. Additionally, stronger inhibiting effects for desirable base-catalyzed reactions versus undesirable acid-catalyzed reactions are responsible for the decrease in alcohol selectivity observed with increasing conversion. We also discuss how the observed alcohol distributions reflect both the nucleophilicity and electrophilicity of the species involved in condensation. Lastly, we show how these results can be used to predict catalytic performance at elevated conversions and the implications of various parameters on the product distributions observed.
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