Synthesis of Long Chain Oxygenates via Aldol Condensation of Furfural and Acetone over Metal-Organic Frameworks

Selective Gas Adsorption in Permanently Microporous Coordination Cages with Exposed Metal Sites

Porous coordination cages (PCCs), molecular analogs of metal-organic frameworks, offer modular platforms for studying the adsorption properties of small molecules, with coordinatively unsaturated metal centers playing a pivotal role in tuning these behaviors. In this work, we present the synthesis, activation, and detailed gas adsorption studies of second-row transition metal-based M24L24 cuboctahedral cages, specifically Mo24(bdc)24, Rh24(bdc)24, and [Ru24(bdc)24]Cl12. These materials represent rare examples of Mo-, Rh-, and Ru-based hybrid porous solids. The synthesis and activation of these cages were optimized to maximize porosity, yielding BET surface areas of up to 832 m2/g. Gas adsorption studies with CO2 and CO reveal distinctive uptake behaviors linked to the metal cations, with Mo24(bdc)24 demonstrating the highest gravimetric CO2 uptake (2.12 mmol/g at 298 K) and [Ru24(bdc)24]Cl12 exhibiting the strongest CO binding (-75 kJ/mol). Additionally, we explore the selective adsorption of unsaturated hydrocarbons, such as ethylene and propylene, revealing strong binding interactions at low pressures as a result of strong metal-hydrocarbon interactions based on pi-backbonding interactions.

Sustainable Aviation Fuel Molecules from (Hemi)Cellulose: Computational Insights into Synthesis Routes, Fuel Properties, and Process Chemistry Metrics

Production of sustainable aviation fuels (SAFs) can significantly reduce the aviation industry's carbon footprint. Current pathways that produce SAFs in significant volumes from ethanol and fatty acids can be costly, have a relatively high carbon intensity (CI), and impose sustainability challenges. There is a need for a diversified approach to reduce costs and utilize more sustainable feedstocks effectively. Here, we map out catalytic synthesis routes to convert furanics derived from the (hemi)cellulosic biomass to alkanes and cycloalkanes using automated network generation with RING and semiempirical thermochemistry calculations. We find >100 energy-dense C8-C16 alkane and cycloalkane SAF candidates over 300 synthesis routes; the top three are 2-methyl heptane, ethyl cyclohexane, and propyl cyclohexane, although these are relatively short. The shortest, least endothermic process chemistry involves C-C coupling, oxygen removal, and hydrogen addition, with dehydracyclization of the heterocyclic oxygens in the furan ring being the most endothermic step. The global warming potential due to hydrogen use and byproduct CO2 is typically 0.7-1 kg CO2/kg SAF product; the least CO2 emitting routes entail making larger molecules with fewer ketonization, hydrogenation, and hydrodeoxygenation steps. The large number of SAF candidates highlights the rich potential of furanics as a source of SAF molecules. However, the structural dissimilarity between reactants and target products precludes pathways with fewer than six synthetic steps, thus necessitating intensified processes, integrating multiple reaction steps in multifunctional catalytic reactors.