Kinetic and mechanistic investigation of Butyl Levulinate synthesis on ZSM-5 supported phosphomolybdic acid

Abstract

Levulinic acid (LA), a biomass-derived platform chemical, serves as a precursor for butyl levulinate (BL), a versatile intermediate with various applications, notably as a green blending molecule for diesel fuel. In this study, phosphomolybdic acid supported on ZSM-5 catalysts was synthesized and utilized as an effective heterogeneous catalyst for the esterification of LA with 1-butanol to produce BL. The synthesized catalysts were characterized for their structure, elemental composition, and surface area using XRD, FTIR, HRTEM, EDS, and BET analysis. The effect of reaction parameters, including catalyst amount, catalyst loading, calcination temperature, reaction temperature, and time on the conversion of LA to BL, are systematically discussed. The catalyst achieved > 95% BL yield and maintained high stability even after eight cycles, highlighting its potential as an efficient catalyst for BL production. A kinetic investigation employing a pseudo-homogeneous model was carried out to explore the activation energy and thermodynamic parameters pertinent to BL production. Additionally, Nucleophilic substitution reactions, alongside the two mechanistic models—Langmuir-Hinshelwood and Eley-Rideal—were employed to comprehensively elucidate the reaction mechanism involved in the heterogeneous catalytic processes.