Activity‐Based Models to Predict Kinetics of Levulinic Acid Esterification

Abstract

The solvent is of prime importance in biomass conversion as it influences dissolution, reaction kinetics, catalyst activity and thermodynamic equilibrium of the reaction system. So far, activity-based models were developed to predict kinetics and equilibria, but the influence of the catalyst could not be predicted by thermodynamic models. Thus, in this work, the thermodynamic model ePC-SAFT advanced was used to predict the activities of the reactants and of the catalyst at various conditions (temperature, reactant concentrations, γ-valerolactone GVL cosolvent addition, catalyst concentration) for the homogeneously acid-catalyzed esterification of levulinic acid (LA) with ethanol. Different kinetic models were applied, and it was found that the catalyst influence on kinetics could be predicted correctly by simultaneously solving the dissociation equilibrium of H2SO4 catalyst along the reaction coordinate and the relating reaction kinetics to proton activity. ePC-SAFT advanced model parameters were only fitted to reaction-independent phase equilibrium data, but the key reaction properties were determined by one experimental kinetic curve for a set of temperatures, yielding the reaction enthalpy at standard state ∆ 𝑅 𝐻 0 = 11.48 𝑘𝐽 𝑚𝑜𝑙 −1 , activation energy 𝐸 𝐴 = 30.28 𝑘𝐽 𝑚𝑜𝑙 −1 and the intrinsic reaction rate constant k = 0.011 s -1 at 323 K, which is independent of catalyst concentration. The new procedure allowed an a-priori identification of the effects of catalyst, solvent and reactant concentration on LA esterification.

Measurement and PC-SAFT Modeling of the Solubility of the BHET Monomer, the BHET Dimer, and PET in Single Solvents

“…A summary of all calculated absolute deviations (AD) and average absolute deviations is given in Tables S2, S3, and S4, respectively, for the solubility measurements of the BHET monomer, the BHET dimer, and PET, in the Supporting Information. The pure-component parameters for the solvents DMSO, GVL, EG, and H 2 O were retrieved from the literature. − Given the structural similarities among the BHET monomer, the BHET dimer, and PET, particularly with respect to the terephthalic acid segment group, the binary interaction parameter k ij between one of these molecules with the same solvent was assumed to be equal. The melting temperatures and enthalpies were taken from Table .…”

Critical Review on the Synthesis of Levulinate Esters from Biomass-Based Feedstocks and Their Application

“…The solvents have an effect on the reaction feedstock dissolution, catalytic activity, and kinetic and thermodynamic equilibrium of the reaction system. , Recently, different kinetic models were used to describe the solvent effects on the acid catalytic synthesis of LEs. , Baco et al studied the solvent effect of acid-catalyzed esterification of LA to EL by the Kalmet-Abboud-Taft equation and a linear solvation energy relationship (Figure ). The solvent systems with high hydrogen-bond acceptor capacity and low polarizability were favored for LA esterification with ethanol.…”

Influence of Solvents and Salts on CO2 Solubility and the Impact on an Esterification Reaction

“…In this work, 2.8 M hydrochloric acid (HCl) was used to provide an acidic environment in all experiments. It is known from the literature that the kind and concentration of the catalyst influence the kinetic profiles, , while in this work, a constant catalyst concentration has been used as described above. As the mole fraction of HCl ( x HCl = 0.001) used in the present work was much lower than the mole fraction of the cosolvents (CO 2 and NMP), the influence of HCl on equilibria was neglected.…”