Investigations Into The Acid-Base Properties Of 2-Butanol Decomposition Over Metal Oxides

Abstract

The kinetics and acid-base properties of the catalytic decomposition of 2-butanol over magnesium oxide, zirconium dioxide and vanadium pentoxide has been investigated using a low-pressure steady-state technique. Research into heterogeneous acidic catalysis has been thorough due to the acidic nature of catalysts involved in petroleum refinery. Industrial applications for heterogeneous basic catalysts are more limited, and as such there is a paucity of information on the subject. Basic catalysts are typically active in the dehydrogenation of alcohols, while acidic catalysts are typically active in the dehydration of alcohols. The metal oxide catalysts investigated in this work, MgO, ZrO₂ and V₂O₅, are respectively basic, amphoteric and acidic in nature. The exposure of 2-butanol to these metal oxides and the kinetics of dehydration to butene and dehydrogenation to 2-butanone are investigated. A low-pressure steady state temperature-programmed reaction spectroscopy technique was used to study the kinetics of these reactions. Separate kinetic models for desorption and gas-surface reactions allow for the determination of activation energies of product formation. Acidic catalysts showed the highest activity towards 2-butanol dehydration. As expected, V₂O₅ was more active than ZrO₂. MgO was found to show the highest activity towards 2-butanol dehydrogenation. The activation energies for dehydration over the three metal oxides followed the series MgO < ZrO₂ < V₂O₅. Trace products formed following the exposure of 2-butanol to each of the catalysts, while complete oxidation to CO₂ and H₂O was also apparent for each catalyst. There were no identifiable trends for activation energies of formation of these products.