Zeolite-β based molecular sieves: A potential catalyst for esterification of biomass derived model compound levulinic acid

Abstract

A series of hetero ions (iron, boron, gallium, titanium, and zinc [Fe3+, B3+, Ga3+, Ti4+, and Zn2+, respectively) incorporated zeolite-β is prepared via a simple hydrothermal method within 48 h at 170 °C. Fourier transform-infrared spectroscopy analysis and powder X-ray diffraction (FT-IR and XRD, respectively) studies demonstrated the formation of the crystalline phase of the zeolite framework with BEA structure. Scanning electron microscope (SEM) images showed a uniform spherical shape with a particle size of < 1 µm. The presence of strong acidic sites and the microporous nature of the materials was evident from sorption studies. The resulting Al-, Ga-, Zn-, and Ti- containing zeolite-β materials showed excellent activity for the esterification of levulinic acid using several alcohols (such as methanol, n-butanol, and amyl alcohol) with a levulinate ester yield of more than 95%. Significant advantages of the protocol include good activity, the use of a green solvent, and easy removal of the catalyst via filtration. The catalyst activity remained almost intact even after several reaction cycles.

Keywords

• Biomass
• Levulinic acid
• Esterification
• Zeolites
• Zeolite-β
• Molecular sieves