• Energy Research

This review presents developments in the chemical processing of fermentation-derived compounds, focusing on ethanol, lactic acid, 2,3-butanediol and the acetone-butanol-ethanol mixture. We examine pathways from these products to biologically-derived drop-in fuels, polymers, as well as commodity chemicals, highlighting the role of homogeneous and heterogeneous catalysts in the development of green processes for the production of fuels and high-value-added compounds from biomass.

AbstractLife‐cycle analysis (LCA) allows the scientific community to identify the sources of greenhouse gas (GHG) emissions of novel routes to produce renewable fuels. Herein, we integrate LCA into our investigations of a new route to produce drop‐in diesel/jet fuel by combining furfural, obtained from the catalytic dehydration of lignocellulosic pentose sugars, with alcohols that can be derived from a variety of bio‐ or petroleum‐based feedstocks. As a key innovation, we developed recyclable transition‐metal‐free hydrotalcite catalysts to promote the dehydrogenative cross‐coupling reaction of furfural and alcohols to give high molecular weight adducts via a transfer hydrogenation–aldol condensation pathway. Subsequent hydrodeoxygenation of adducts over Pt/NbOPO4 yields alkanes. Implemented in a Brazilian sugarcane biorefinery such a process could result in a 53–79 % reduction in life‐cycle GHG emissions relative to conventional petroleum fuels and provide a sustainable source of low carbon diesel/jet fuel.

AbstractWe investigate syngas production from polyolefins commonly found in solid waste in a semi‐batch reactor system via gasification and catalytic reforming. We find that the gasification behavior of polymer waste is correlated to the energy of the weakest CH bond in the polymer structure. Furthermore, we show that the syngas yield can be enhanced by the use of adsorbents and reforming catalysts, which promote gasification and reforming over pyrolysis reactions. Adsorbents are required for the achievement of high syngas yields when the polymer feed is comprised of polymers that pyrolyze at lower temperatures, such as PS, PP, and LDPE, resulting in carbon loss as light hydrocarbons. Adsorbents trap these light gases and release them at a higher temperature, where reforming over a Ni/Al2O3 catalyst can take place. This behavior also results in synergistic effects when blends of polymers are gasified. The Ni/Al2O3 catalyst is stable over multiple recycle reactor runs.

AbstractAviation fuel (i.e., jet fuel) requires a mixture of C9–C16 hydrocarbons having both a high energy density and a low freezing point. While jet fuel is currently produced from petroleum, increasing concern with the release of CO2 into the atmosphere from the combustion of petroleum‐based fuels has led to policy changes mandating the inclusion of biomass‐based fuels into the fuel pool. Here we report a novel way to produce a mixture of branched cyclohexane derivatives in very high yield (>94 %) that match or exceed many required properties of jet fuel. As starting materials, we use a mixture of n‐alkyl methyl ketones and their derivatives obtained from biomass. These synthons are condensed into trimers via base‐catalyzed aldol condensation and Michael addition. Hydrodeoxygenation of these products yields mixtures of C12–C21 branched, cyclic alkanes. Using models for predicting the carbon number distribution obtained from a mixture of n‐alkyl methyl ketones and for predicting the boiling point distribution of the final mixture of cyclic alkanes, we show that it is possible to define the mixture of synthons that will closely reproduce the distillation curve of traditional jet fuel.