From Molecular Level to Process Design: Cosolvent-free Homogeneous Conversion of Levulinic Acid to γ-Valerolactone

High Resolution Image Download MS PowerPoint Slide γ-Valerolactone (GVL) is a promising biomass-derived platform molecule to produce sustainable fuels and chemicals. Although highly active homogeneous Ru-based catalysts enable near-quantitative conversion of levulinic acid (LA), their implementation in process design has remained severely limited by the lack of reliable kinetic and thermodynamic data, especially under favorable cosolvent-free conditions. Herein, we report a comprehensive molecular-to-process design for the Ru(acac) 3 /1,4-bis(diphenylphosphino)butane-catalyzed transformation of LA to GVL. Deuterium-labeling experiments and kinetic studies identified molecular hydrogen activation as the rate-determining step with an apparent zero-order dependence on LA. A coupled kinetic model was developed that explicitly accounts for conversion-dependent inherent density changes, an effect typically neglected but shown to be critical for accurate kinetic interpretation of cosolvent-free systems. The temperature-dependent measurements provided the apparent activation enthalpy ( ΔH ‡ app ) of 113.5 ± 8.5 kJ mol –1 and apparent activation entropy ( ΔS ‡ app ) of +53.1 ± 20.2 J mol –1 K –1 . The first experimental vapor–liquid equilibrium data for the GVL–LA system, along with density and viscosity data for GVL–LA–H 2 O mixtures, which enable reliable process simulation, were also reported. A conceptual process design for GVL production using Aspen-based simulation was additionally developed, illustrating the direct translation of molecular-level understanding into a process design. This work highlights the importance of coupling detailed reaction engineering with experimentally grounded thermodynamics to bridge the gap between molecular-level understanding and conceptual process design.