|Thermodynamics equilibirum reaction kinetics heterogeneous hydrolysis ion-exchange resin calorimetry|
The thermodynamics and kinetics of the hydrolysis of four esters (methyl formate, methyl acetate, ethyl formate, and ethyl acetate) were investigated experimentally and theoretically. An acidic ion-exchange resin was used as heterogeneous catalyst and adsorbent. Alternatively, hydrochloric acid was used as a homogeneous catalyst. The chemical reaction equilibrium was measured for various temperatures and initial concentrations of the reactants using conventional batch reactor runs. The influence of the absence and presence of the solid catalyst on the liquid-phase equilibrium composition was also studied in a batch reactor. The relevant distribution equilibria of the components involved were quantified based on pulse chromatographic experiments. To investigate the kinetics of the four reactions, a reaction calorimeter was employed. Systematic experiments to measure heat flows due to reaction were carried out with catalyst suspensions in the calorimeter. Reaction rate constants were quantified from the measured heat flows. The four hydrolysis reactions were found to proceed with very different reaction rates. The fastest reaction was the hydrolysis of methyl formate. The slowest was the hydrolysis of ethyl acetate. For comparison, reaction rate constants were also quantified from concentration-time profiles recorded in conventional batch experiments. A simplified pseudo-homogeneous model and the determined parameters were found to be capable of describing the heat flows measured in the reaction calorimeter for all reactions studied under diverse operating conditions. The thermodynamic and kinetic parameters determined in this work form a platform to design and optimize chromatographic reactors for the hydrolysis reactions investigated and the corresponding esterifications.