Esterification Of Propionic Acid Research Articles

Some physico-chemical properties and catalytic activity of sulfate ion supported on WO3/SnO2 catalyst

Solid acid catalyst 15wt%WO3/SnO2 was synthesized and loaded with 15wt%SO4. The obtained catalyst was calcined at 400, 500, 650 and 800°C. The prepared catalysts were characterized by TG-DTA, XRD, FTIR and N2 adsorption at −196°C. The surface acidity was measured by non aqueous potentiometric titration and FT-IR spectra of chemisorbed pyridine. The catalytic performance was evaluated on the esterification of propionic acid with n-butanol in liquid phase. The TG-DTA analysis shows that the decomposition of sulfate species occurred at >500°C. XRD measurements showed that WO3 dispersed completely on the surface of SnO2 and that the sulfating of WO3/SnO2 tends to hinder the crystallization of SnO2. The specific surface area, total pore volume and micropore volume are increased with increasing thermal treatment up to 500°C, and then decreased gradually with a further increase in calcination temperature. The prepared catalysts possess very strong acid sites and contain both Brønsted and Lewis acid sites. The total surface acidity decreased with raising of the calcination temperature. The highest conversion of propionic acid was for 400°C product, and decreased with an increase in calcination temperature. The effect of the reaction parameters, i.e., time of reaction, reaction temperature, and reactant molar ratio and the weight of the catalyst were also studied. The reaction obeys the second order kinetic equation with respect to propionic acid concentration. Brønsted and Lewis acid sites appeared to be needed for catalytic activity in n-butyl propionate formation.

N-Propyl Propionate Synthesis via Catalytic Distillation - Experimental Investigation in Pilot-Scale

Catalytic distillation experiments were designed and carried out in a pilot-scale column to prove the technical feasibility of the heterogeneously catalyzed n-propyl propionate synthesis by esterification of propionic acid with 1-propanol using the surface-sulfonated ion-exchange resin Amberlyst 46. The experiments cover a broad range of decisive operational parameters, for example, reflux ratio, column load, distillate-to-feed ratio, and molar feed ratio of the reactants. The reconciled results comprise a complete set of concentration and temperature profiles along the column height and, hence, exhibit detailed and reliable data for model validation purposes.

Incorporation of vapor permeation process to esterification reaction of propionic acid and isopropanol for performance improvement

A commercial tubular zeolite membrane (NaA) was employed in a vapor permeation system to dehydrate the reaction mixture during the esterification of propionic acid with isopropanol. The reaction was performed in a batch reactor, using Amberlyst 15 as a catalyst with different weight fractions relative to propionic acid. Experiments were conducted to investigate the effect of the alcohol-to-acid molar ratio on the performance of the hybrid process. The integration of the chemical reaction with the vapor permeation process significantly enhanced the conversion of the reversible esterification reaction. It was observed that contrary to the effect of increasing alcohol-to-acid molar ratio from 1: 1 to 1.5: 1, the acid conversion and the permeated water flux decreased when the reactants molar ratio increased from 1.5: 1 to 3: 1. This effect was due to the reducing effect of reaction mixture composition on the boiling point and reaction and evaporation rates during the hybrid process. Also, increasing catalyst loading had noticeable influence on the acid conversion and the permeated water flux.

Microwave-Promoted Synthesis of n-Propyl Propionate using Homogeneous Zinc Triflate Catalyst

The esterification of propionic acid with 1-propanol to produce n-propyl propionate was studied under microwave and conventional heating conditions using a variety of homogeneous and heterogeneous catalysts looking for possible rate enhancement. Direct evaluation of the heating methods was done by comparing the ester yields after 30 min of equimolar reaction at 100 °C. Several catalysts were found to produce more product than the ion-exchange resin Amberlyst 46 under both heating methods and the same catalyst loading. From these catalysts, Zn triflate proved to be more effective under microwave heating conditions producing 40% more ester compared to the conventionally heated experiment. FT-IR spectra showed that there were no changes in the chemistry of the components and that hydrolysis of Zn triflate into triflic acid, which could promote the reaction, is not likely to occur.

Heterogeneous Catalysed Esterification of Propionic Acid with n-Amyl Alcohol over a Microporous Cation-exchange Resin Dowex 50Wx4

Abstract Kinetics of heterogeneous catalysed esterification of propionic acid with n-amyl alcohol was studied with a microporous cation-exchange resin catalyst, Dowex 50Wx4, in a stirred batch reactor to synthesise amyl propionate. Effects of various parameters such as speed of agitation, catalyst loading, and reaction temperature on reaction rate were investigated. The equilibrium conversion of propionic acid increased with in catalyst loading and reaction temperature. Stirrer speed had virtually no effect on the reaction rate under the experimental conditions. The apparent activation energy was found to be 43.167 kJmol−1 for the formation of amyl propionate and the equilibrium constant, which is independent of temperature ranging from 318 to 348 K, was found to be 4.05. It was also observed that the initial reaction rate decreased with water concentrations and increased with that of acid and increased with that of alcohol linearly. The reaction was found to occur between an adsorbed acid molecule and a molecule of alcohol in the bulk and it was concluded that the reaction mechanism can be represented by Eley-Rideal model.

Synthesis of p-cresylpropionate over M n+-montmorillonite catalysts: aspect of catalyst solvent interactions by DRIFTS study

Different metal ion-exchanged montmorillonite based clay catalysts (Mn+-mont; Mn+ = Al3+, Fe3+, Cr3+, Zn2+, Ni2+, Mn2+, Cu2+ and H+) were prepared and characterized by various physico-chemical techniques. The clay catalysts were evaluated for the esterification of propionic acid with p-cresol. Our DRIFTS (Diffuse Reflectance Infrared Fourier Transform Spectroscopy) study of the catalysts treated with propionic acid supported the very well established mechanism of esterification. Furthermore, the esterification was conducted in the presence of different solvents such as benzene, toluene, o-xylene and 1,4-dioxane. Interestingly, the reaction carried out in the presence of 1,4-dioxane did not yield any product. The role played by this specific solvent in preventing the formation of ester product has been investigated by DRIFTS study involving catalyst and solvent interaction.

Brønsted and Lewis acidity of modified montmorillonite clay catalysts determined by FT-IR spectroscopy

The surface acidity of different modified montmorillonite clay catalysts, Al 3+-exchanged montmorillonite (Al 3+-Mont) and aluminium pillared montmorillonite (Al-PILC) was determined by DRIFTS (diffuse reflectance Fourier transform infrared spectra) using pyridine as probe molecule. The method involved treating the clay sample directly with pyridine, drying the sample at 120 °C and recording FT-IR spectra in the region 1650 and 1350 cm −1. The spectra obtained showed well resolved absorption bands for Lewis and Brønsted acid sites in the clay catalysts. In order to understand the role of acid sites present on clay catalysts, esterification of propionic acid with p-cresol has been studied. The Brønsted acidity data obtained by FT-IR study for modified montmorillonite clay catalysts correlated well with the catalytic activity in the esterification reaction. Among the modified clay catalysts, Al 3+-Mont and H +-Mont clay catalysts showed good activity and Al-PILC showed negligible activity in esterification. The inactivity of Al-PILC catalysts is attributed to the absence of Brønsted acidity.

Suppression of catalyst deactivation by means of acoustic irradiation—Application on fine and specialty chemicals

The effect of acoustic irradiation has been studied in several hydrogenation reactions (1-phenyl-1,2-propanedione, ethyl-pyruvate and d -fructose hydrogenation) as well as in an esterification reaction over various heterogeneous catalysts. The reaction rate and selectivity were significantly improved under sonification in 1-phenyl-1,2-propanedione hydrogenation over Pt/SF (silica fiber) catalyst. Acoustic irradiation enhanced the reaction rate in esterification of propionic acid with ethyl alcohol over functionalized polymer fiber Smopex-101 catalyst compared to identical silent conditions. Furthermore, ultrasound remarkably suppressed catalyst deactivation in d -fructose hydrogenation over Raney-Ni catalyst. The spent catalysts used in the hydrogenation reactions either in presence or absence of acoustic irradiation were intensively studied by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

Esterification of propionic acid under microwave irradiation over an ion-exchange resin

Esterification of propionic acid with ethyl alcohol over an ion-exchange resin catalyst was studied under microwave dielectric heating. Experiments were carried out in a single-mode microwave loop reactor, equipped with a heating band as well to directly compare the efficiency of the conventional convective/conductive heating and microwave dielectric heating. Series of kinetic experiments were carried out with both conventional and dielectric heating at the reaction temperature of 105 °C and total pressure of 7 bar. Different initial molar ratios of propionic acid-to-ethanol (from 1:2 to 2:1) were investigated. Initial molar ratios of acid-to-alcohol significantly affected the final yield of the desired product ethyl ester of propionic acid, ethyl propionate. The highest product yield was observed with equimolar initial ratio, compared to 1:2 and 2:1 initial molar ratios of acid-to-alcohol. However, the kinetics and equilibrium of this reaction were unaffected by the method of heating (microwave or conventional).

Liquid-Phase Esterification of Propionic Acid with n-Butanol

Kinetic data on the esterification of propionic acid with n-butanol catalyzed by Amberlyst 15, Amberlyst 35, Amberlyst 39, and HZSM-5 pellets were measured at the temperatures from 353 to 383 K in a stirred batch reactor. The data indicated that the Amberlyst series resins were all effective to carry out this esterification. Because of the insignificance of the interphase and intraparticle mass-transfer resistances, a quasi-homogeneous model employing the activity of each species was used to correlate the experimental data for Amberlyst 35. A possible mechanism of this reaction was found to follow the Rideal−Eley theory in which an adsorbed and protonated propionic acid molecule reacted with an n-butanol molecule in the bulk. The activation energy of the forward reaction was found to be 14.1 kcal/mol. The activity-based equilibrium constant was found to increase slightly with an increase in temperature, indicating that this reaction is nearly isothermal.

Synthesis of butyl propionate using novel aluminophosphate molecular sieve as catalyst

The esterification of propionic acid with n-butanol at 126–133°C in the presence of catalytic quantities of novel aluminophosphate molecular sieve AP-9 gives the corresponding esterified product in a high yield. The effects of the amount of catalyst used, reaction time, the molar ratio of alcohol to acid, the amount of cyclohexane used, reaction temperature, the kinds of catalyst, and the methods of preparing the catalysts, on the synthesis of butyl propionate have been investigated. The yield of butyl propionate obtained was 85.3% when the reaction conditions employed were as follows: catalyst: propionic acid: n-butanol: cyclohexane=1.0 g: 1 mol: 1.2 mol: 5.0 ml, at 126–133°C for 5 h. The aluminophosphate molecular sieve AP-9 can be recovered and reused to give almost the same yield as that given by a fresh aluminophosphate molecular sieve.

DYNAMICS OF ADSORPTIVE REACTOR WITH A BIMOLECULAR REACTION

A theoretical analysis is used to gain insight in the dynamics of an adsorptive fixed-bed reactor where an irreversible bimolecular reaction of the type A + B→P takes place. One of the reactants is assumed to be preferentially adsorbed with a favorable isotherm, while the other is adsorbed with a linear isotherm. The reaction follows an arbitrary kinetics where the rate is dependent on the concentrations of A and B. An analytic solution based on the method of characteristics is obtained for the case of local adsorption equilibrium. The dynamic behavior is affected by an intimate coupling of reaction kinetics and adsorption and breakthrough of the favorably adsorbed species is delayed by the occurrence of the reaction. The theoretical analysis is compared to experimental results obtained for an immobilized-enzyme reactor system for the esterification of propionic acid and isoamyl alcohol in hexane. The local adsorption equilibrium solution obtained for this system is in qualitative agreement with the experimental results. Quantitative agreement is obtained taking into account numerically the finite rate of adsorption and axial dispersion.

Catalysis by Heteropoly Compounds .XXII. Reactions of Esters and Esterification Catalyzed by Heteropolyacids in a Homogeneous Liquid-Phase Effects of the Central Atom of Heteropolyanions Having Tungsten as the Addenda Atom

Decomposition of isobutyl propionate (IBP) (Reaction (1)), ester exchange of IBP with acetic acid (Reaction (2)), ester exchange of IBP with n-propyl alcohol (Reaction (3)), and esterification of propionic acid with isobutyl alcohol (Reaction (4)) have been studied in a homogeneous liquid phase using heteropolyacids H m XW 12O 40 ( X = P, Si, Ge, B, and Co) having the Keggin structure and H 6P 2W 18O 62, having the Dawson structure. The results clearly indicated that the catalytic behavior of heteropolyacids remarkably depended on the kind of reaction system, namely, the basicity of reactants. For Reaction (1), the catalytic activities of the heteropolyacids were 60-100 times higher than those of H 2SO 4 and p-toluenesulfonic acid. Among the heteropolyacids, the activity was in the order H 3PW 12O 40 ≥ H 4SiW 12O 40 ∼ H 4GeW 12O 40 > H 5BW 12O 40 > H 6CoW 12O 40. This order suggests that the activity follows the order of the acid strength of the solutions of heteropolyacids, which increases with the decrease in the negative charge of the polyanion. H 6P 2W 18O 62 showed an activity between those of H 5BW 12O 40 and H 6CoW 12O 40. Water molecules in the system retarded Reaction (I). For Reaction (2), the activity order was similar to that for Reaction (I) in the absence of water. However, contrary to Reaction (1), the addition of water greatly accelerated Reaction (2). It was presumed that, in the presence of water, Reaction (2) proceeds via the hydrolysis of IBP to propionic acid and isobutyl alcohol, followed by the esterification of isobutyl alcohol with acetic acid. On the other hand, the difference in the activity between the heteropolyacids and H 2SO 4 was not significant for Reactions (3) and (4), for which the effective acid strength of the catalysts may level off as a consequence of the leveling effect of the reactant alcohols.