Kinetic Study of Acetic Acid Esterification with Methanol Catalyzed by Gel and Macroporous Resins

Abstract

The liquid-phase acetic acid esterification kinetics with methanol to methyl acetate and water catalyzed by gel (Lewatit K1221) and macroporous (Lewatit K2629) ion exchange resins have been investigated and compared with literature reported data acquired on Amberlyst 15. The effects of the resin swelling, the initial molar methanol to acetic acid ratio (1:1 -10:1) and the temperature (303 -333 K) on the reaction kinetics were investigated. The gel type resin exhibits a remarkably higher catalytic activity compared to the macroporous resins, despite its similar number of sulfonic acid groups. This can be attributed to the differences in active site accessibility during reaction and, hence, in resin swelling, especially when it is in contact with polar components, such as water and methanol. The differences in catalytic behavior between the considered resins have been assessed using an exchange based Eley-Rideal model in which it is assumed that (1) all the active sites are occupied, (2) the acid undergoes a proton exchange with the protonated methanol and (3) the reaction occurs according to an Eley-Rideal mechanism with the surface reaction between protonated acetic acid and methanol from the bulk as ratedetermining step. This model, which implicitly accounts for resin swelling, could describe the observed differences between the various resins. The activation energy was determined at 47 kJ mol -1 , irrespective of the resin used.

Catalytic activity dependence on morphological properties of acidic ion-exchange resins for the simultaneous ETBE and TAEE liquid-phase synthesis

“…The catalytic activity is better correlated with physicochemical and ISEC properties of the catalyst rather than with dry state properties, since no significant correlation was found for catalytic activity with any dry state property. This is coherent because, as seen in volumetric swelling experiments and in agreement with the literature, 16 IER swell similarly in EtOH and in water. Therefore, ISEC properties should be more representative of the actual working-state of the catalyst in the studied etherification reactions.…”

“…Several factors are involved in the swelling phenomenon as the nature of the solvent (polar or non-polar), the resin crosslinking degree, the nature of the functional groups and its concentration. 16 All tested resins swelled in contact with solvents though in very different extent. In agreement with literature, 1,16 water was found to be the solvent that produced the largest swelling for all IER.…”

“…16 All tested resins swelled in contact with solvents though in very different extent. In agreement with literature, 1,16 water was found to be the solvent that produced the largest swelling for all IER. SR values obtained were slightly higher in water than in MeOH and EtOH, indicating that resins swelling in water and in C 1 -C 2 alcohols are comparable.…”

“…The degree of swelling of a resin immersed in different solvents can be quantified by means of the swelling ratio (SR), which can be defined as the ratio of the volume of swollen resin, in a particular solvent, to the volume of dry resin. 16 Graduated test tubes of 50 mL were used in these measurements conducted at room temperature (293 K). 35 mL of solvent were added to 10 mL of dry resin with commercial particle size and after 24 h, SR was determined for each combination of resin and solvent from the final volume of swollen polymer.…”

Catalyst Stability Assessment in a Lab-Scale Liquid-Solid (LS)² Plug-Flow Reactor

“…Hence, as an example case study, the Lewatit K2629 catalyst is evaluated in the (LS) 2 plug-flow reactor for the transesterification of ethyl acetate and methanol towards methyl acetate and ethanol (see also Scheme 1). This catalyst is a strongly acidic macroporous resin with 4.8 mol kg −1 sulfonic acid groups as active sites and is known to be fully recyclable in a batch reactor [61]. In this work, a lab-scale liquid-solid (LS)² plug-flow reactor with a fixed catalyst bed is designed aiming at assessing deactivation phenomena of heterogeneous catalysts in liquid-phase reactions.…”