Thermophysical properties of 5-methylfurfural with alcohol additives: Toward efficient and sustainable biofuel blends.

The transition toward sustainable energy systems requires renewable fuel alternatives with optimized combustion performance and reduced emissions. 5-Methylfurfural (MFF), a lignocellulosic biomass-derived furanic compound, has emerged as a promising biofuel precursor and blending. In this study, we investigated the thermophysical properties and molecular interactions of binary mixtures of MFF with short-to medium-chain 2-alkanols (C3-C6), combining experimental measurements of density and viscosity with molecular dynamics (MD) simulations. Our findings reveal strong hydrogen-bond interactions between MFF's aldehyde group and the hydroxyl groups of short-chain alcohols, leading to compact molecular packing, enhanced volatility, and improved combustion efficiency. Conversely, longer-chain alcohols introduce steric hindrance that disrupts hydrogen-bonding networks, increasing free volume and diffusivity, thereby influencing ignition delay and miscibility with conventional fuels. These results provide molecular-level insights into customizing viscosity, density, and volatility of renewable fuel blends, thereby enabling the design of advanced biofuels with improved engine compatibility and environmental performance.