DTAB Mediated Post Modification of Zeolite H-BEA, Its Characterization and Catalytic Application for n-Butyl Levulinate Synthesis

The present study focused on the modification of zeolite H-BEA via a desilication post-synthetic approach in the presence of a cationic surfactant, dodecyltrimethyl ammonium bromide (DTAB), to synthesise a micro-meso composite of zeolite BEA (mesozeolite BEA). Several techniques were used to characterise the modified zeolite H-BEA catalyst, including scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), ²⁹Si and ²⁷Al magic angle spinning nuclear magnetic resonance (MAS-NMR), high and low angle X-ray diffraction (XRD), Fourier transformed infrared (FT-IR) spectroscopy, N₂ sorption isotherms analysis etc. The synthesised mesozeolite exhibited bimodal porosity (micro and meso) and enhanced catalytic characteristics (surface area, acidity, and thermal strength) as compared to the parent zeolite H-BEA. The catalytic potential of the micro-meso H-BEA catalyst was investigated in the esterification of levulinic acid (LA) to n-butyl levulinate. The Box-Behnken Design (BBD) approach was used to optimise the process parameters for the catalytic reaction. Analysis of variance (ANOVA) was implemented to examine the appropriateness and importance of the quadratic model. The synthesised mesozeolite was found to be a highly efficient catalyst under the optimized reaction conditions, with 99.2% LA conversion, 97% yield, and 97% selectivity of n-butyl levulinate.

Graphical Abstract

Mesozeolite H-BEA catalyzed synthesis of n-butyl levulinate, a value-added chemical