From molecular level to process design: Co-solvent-free autocatalytic homogeneous hydrogenation of C5-platform chemical furfural to furfuryl alcohol

• A solvent-free Ru-based autocatalytic hydrogenation catalyst system was revealed. • A kinetic model was developed for the selective Ru-catalyzed reduction of furfural. • A conceptual process design was developed for the continuous production of furfurol. Furfuryl alcohol (FOL) has been considered a valuable biomass-based platform chemical. We recently developed a Ru(acac) 3 /1,4-bis(diphenylphoshino)butane, Ru(DPPB)-based homogeneous catalyst for the selective conversion of furfural (FAL) to FOL; however, detailed kinetic study and process modeling have not been performed, yet. Herein, we revealed that the co-solvent-free Ru(DPPB)-catalyzed selective hydrogenation of FAL to FOL proceeds via an autocatalytic mechanism. Moreover, it was proven that FOL facilitates the formation of catalytically active Ru species, as well as the presence of transfer hydrogenation between FAL and FOL using deuterium-labeling experiments. According to the best of our knowledge, no autocatalytic reactions have been evidenced under neat conditions. Based on this theory, a detailed kinetic study was subsequently performed, and a kinetic model was proposed to account for all the characteristics of the experimental series. The corresponding rate coefficients were determined in the temperature range of 413.1–433.1 K, enabling us to calculate the activation enthalpies and entropies for the precatalyst activation, the direct hydrogenation reaction, and the autocatalytic pathway. The corresponding activation parameters were found to be Δ H app ‡ = 107.4 ± 7.0 kJmol −1 and Δ S app ‡ = − 35.2 ± 16.8 Jmol –1 K −1 , Δ H app ‡ = 132.8 ± 7.2 kJmol −1 and Δ S app ‡ = 32.3 ± 17.1 Jmol –1 K −1 , Δ H app ‡ = 116.2 ± 2.0 kJmol −1 and Δ S app ‡ = 12.0 ± 4.9 Jmol –1 K −1 , respectively. Applying the kinetic and thermodynamic parameters, a simplified flowsheet was also developed to demonstrate the continuous production of FOL completing the concept of “ from Molecular Level to Process Design (MoLePoD) ”.