Production of 1,3 butadiene from ethanol over mixed oxide catalysts

Finding alternative sources for the production of petroleum-based products is important to accommodate an increase in the use of renewable energy sources. Butadiene is typically produced as a byproduct through the refining of petroleum. Using ethanol as a renewable resource for the production of butadiene is one potential method. Various hydrotalcite-like materials were prepared via co-precipitation methods and thermally treated to produce binary mixed metal oxide catalysts over a range of metal cation ratios. Magnesium, calcium, and copper were investigated as the bivalent cations and aluminum, chromium, and iron were investigated as the trivalent cations in this study. Since the coupling of ethanol is an acid-base bifunctional catalyzed reaction, fine-tuning of the strength and distribution of sites was required for production of butadiene and minimization of byproduct formation, which was achieved by varying the ratio for each combination of divalent and trivalent cation investigated. Adsorption microcalorimetry was used to probe acidity and basicity of the catalysts using ammonia and carbon dioxide, respectively. The gas-phase reaction was performed in a plug flow reactor at atmospheric pressure and temperatures from 250°C to 350°C. Conclusions relating the reactivity to the calorimetery were made.