Kinetic study of the esterification of t-cinnamic acid over Preyssler structure acid

Levulinic Acid Esterification with n-Butanol over a Preyssler Catalyst in a Microwave-Assisted Batch Reactor: A Kinetic Study

“…The microwave effect in the esterification reaction of levulinic acid with n -butanol was modeled using a pseudohomogeneous reversible model (PH), while the catalytic effect was modeled using different heterogeneous kinetic models (LHHW or ER). Specifically, two models based on the LHHW mechanism and four based on the ER mechanism were proposed according to successful results obtained in our previous studies about the esterification of other fatty acids. , Table shows the optimized kinetic parameters for the six models (PH-LHHW or PH-ER), where the corresponding parameters for both the microwave and the catalytic effects are shown. The best adjustments of the experimental conversion data were achieved with PH-ER-1 ( R 2 = 0.9896) and PH-ER-4 ( R 2 = 0.9896), which correspond to heterogeneous models where the surface reaction (only levulinic acid is adsorbed and only n -butyl levulinate is desorbed) and the desorption of n -butyl levulinate (only n -butanol is adsorbed) are assumed to be the rate-limiting steps, respectively.…”

“…The catalyst has already been synthesized, characterized, and previously used by our research group, demonstrating successful applications in various syntheses such as the etherification of 5-hydroxymethylfurfural, 69 synthesis of fluorinated hexahydropyrimidine derivatives, 70 and esterification of cinnamic acid. 45 In this work, confirmation of the material structure was achieved through Fourier transform infrared spectroscopy (FT-IR). The FT-IR spectra were acquired in the 400−4000 cm −1 range using pellets with KBr in a Thermo Bruker IFS 66 FT-IR instrument.…”

“…Table shows six heterogeneous kinetic models, based on the previous approaches, that were proposed for modeling the catalytic effect on the levulinic acid esterification, according to the best results of previous such as lauric and trans -cinnamic acid. , The net reaction rate ( r A ) for the formation of levulinic acid is given by eq , which considers both the microwave ( r A , MW ) and catalytic effect ( r A , Cat ). r A = r A , M W + r A , C a t = r A , M W − W V r …”

“…Kinetic studies about esterification of lauric acid and trans -cinnamic acid using a Keggin and a Preyssler heteropolyacid as catalysts, , respectively, have been reported in our previous works, where the conventional heating method was used to produce alkyl esters. However, it has some drawbacks such as the inability to provide homogeneous heating, high energy consumption, long reaction time, formation of byproducts, and low yield. , Hence, recently, several alternatives such as supercritical, − ultrasonic, , and microwave , methods have been used for biodiesel production.…”

“…The literature review showed that heterogeneous catalysts based mainly on Keggin-type heteropolyacids have been studied for esterification of levulinic acid or other fatty acids, as shown in entries 8–17 and 21–25 from Table and additional references. − These have received considerable attention due to their easy synthesis, strong Brönsted acidity, and feasibility of anchoring over supports with high surface areas, allowing use in many catalytic applications. Additionally, heteropolyacids with Wells–Dawson and Preyssler structures supported on silica have been evaluated in the esterification of levulinic acid and cinnamic acid. − Specifically, the Preyssler heteropolyanion is [P 5 W 30 O 110 Na] 14– where five [PW 6 O 24 ] q − units share corner-sharing oxygen to form a cyclic structure, existing a cavity in the center of the molecule in which Na, Y, Ca, or lanthanide metals except La or Bi can be located in this cavity . The corresponding heteropolyacid (heteropolyanion with 14 acidic protons) is an efficient superacid solid catalyst that can be used as a heterogeneous catalyst, which can be considered a green catalyst regarding noncorrosive properties, safety, and stability …”