Activity-based models to predict kinetics of levulinic acid esterification

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 on kinetics has not been succesfully predicted by thermodynamic models. 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 by relating reaction kinetics to proton activity. ePC-SAFT advanced model parameters were only fitted to reaction-independent phase equilibrium data. The key reaction properties were determined by applying ePC-SAFT advanced to one experimental kinetic curve for a set of temperatures, yielding the reaction enthalpy at standard state urn:x-wiley:14394235:media:cphc202200729:cphc202200729-math-0001 , activation energy urn:x-wiley:14394235:media:cphc202200729:cphc202200729-math-0002 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

Prediction of pH in multiphase multicomponent systems with ePC-SAFT advanced

Proton activity, which is usually expressed as a pH value, is among the most important properties in the design of chemical and biochemical processes as it determines the dissociation of species in aqueous mixtures. This article addresses the prediction of pH values in multiphase systems based on the IUPAC definition via proton activity. The required proton activity coefficients were predicted using the thermodynamic equation of state ePC-SAFT advanced. The developed framework considers reaction equilibria and phase equilibria (vapor–liquid and liquid–liquid) to predict pH in the equilibrated liquid phases

Biocatalyst and continuous microfluidic reactor for an intensified production of n-butyl levulinate: kinetic model assessment

International audienceThe use of enzymes to catalyze chemical reactions has increased these recent years. Several models have been developed to express the kinetics over these biocatalysts. The most well-known of them, Michaelis-Menten, is used when only one substrate adsorbs on the enzyme. In the case of the esterification reaction, i.e., bimolecular system, a more complex kinetic model such as the Ping-Pong Bi-Bi should be applied. The use of such advanced models is essential for reactor scaleup and to optimize production. However, these models usually do not consider the reaction temperature. To fill this gap, a Ping-Pong Bi-Bi model was developed to produce butyl levulinate from the esterification of levulinic acid over an immobilized enzyme, Novozym®435. Microfluidic technology was used to ensure ideal mixing conditions. The Ping-Pong model, considering inhibition mechanisms, fits the experimental concentrations. ePC-SAFT equation of state was used to estimate the equilibrium constants

Activity‐based models to predict kinetics of levulinic acid esterification

International audienceThe 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 dH0=11.48 kJ/mol, activation energy EA=30.28kJ/mol and the intrinsic reaction rate constant k=0.011 s-1 at 323 K, which is independent of catalyst concentration. The new model allows predicting the effects of catalyst, solvent and reactant ratio on LA esterificatio

Biocatalyst and continuous microfluidic reactor for an intensified production of n-butyl levulinate: kinetic model assessment

International audienceThe use of enzymes to catalyze chemical reactions has increased these recent years. Several models have been developed to express the kinetics over these biocatalysts. The most well-known of them, Michaelis-Menten, is used when only one substrate adsorbs on the enzyme. In the case of the esterification reaction, i.e., bimolecular system, a more complex kinetic model such as the Ping-Pong Bi-Bi should be applied. The use of such advanced models is essential for reactor scaleup and to optimize production. However, these models usually do not consider the reaction temperature. To fill this gap, a Ping-Pong Bi-Bi model was developed to produce butyl levulinate from the esterification of levulinic acid over an immobilized enzyme, Novozym®435. Microfluidic technology was used to ensure ideal mixing conditions. The Ping-Pong model, considering inhibition mechanisms, fits the experimental concentrations. ePC-SAFT equation of state was used to estimate the equilibrium constants

Activity‐based models to predict kinetics of levulinic acid esterification

International audienceThe 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 dH0=11.48 kJ/mol, activation energy EA=30.28kJ/mol and the intrinsic reaction rate constant k=0.011 s-1 at 323 K, which is independent of catalyst concentration. The new model allows predicting the effects of catalyst, solvent and reactant ratio on LA esterificatio

Solvent effect investigation on the acid-catalyzed esterification of levulinic acid by ethanol aided by a Linear Solvation Energy Relationship

International audienceWhen processing lignocellulosic biomass materials to obtain platform molecules such as levulinic acid (LA), alkyl levulinates or -valerolactone (GVL), the choice of solvent is of prime importance for kinetics. The knowledge of relationships between reaction kinetics and solvent serves as a decision tool for process design. To determine such relationships, esterification reactions was chosen because such reaction steps are present in several biomass conversion processes. In this work, kinetic models of LA esterification by ethanol over sulfuric acid in polar aprotic solvent (GVL) and polar protic solvents (water or ethanol) were developed and evaluated by Bayesian statistics. The apparent dissociation constants in solvents were estimated by ePC-SAFT approach to distinguish the proton concentration from the rate constants. The developed models can fit the experimental concentrations of ethyl levulinate and predict the proton concentration. Using the Kalmet-Abboud-Taft equation, linear relationships between estimated rate constants and solvent properties were established at different temperatures. We observed that solvents with low polarizability and high bond acceptor capacity should be favored for this reaction. Hence, the reaction of esterification is faster in ethanol solvent than in GVL solvent than in water solvent