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A novel microwave-assisted hydrothermal route for the synthesis of ZnₓTPA/γ-Al₂O₃ for conversion of carbohydrates into 5-hydroxymethylfurfural

Parameswaram, G., Roy, Sounak
RSC advances 2018 v.8 no.50 pp. 28461-28471
Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, acidity, catalysts, catalytic activity, differential thermal analysis, energy efficiency, fructose, hydroxymethylfurfural, microwave treatment, pyridines, scanning electron microscopy, solvents, surface area, temperature, thermal properties, thermogravimetry, zinc
Energy-efficient and sustainable processes for the production of 5-hydroxymethylfurfural (HMF) from carbohydrates are in high demand. Bivalent ion-exchanged microwave-synthesized ZnₓTPA/γ-Al₂O₃ was employed for the direct conversion of carbohydrates into HMF. The as-synthesized samples were structurally characterized by FTIR and Raman spectroscopy, UV-Vis diffused reflectance spectroscopy, and X-ray diffraction. Thermal characterization was performed by TG-DTA. The surface morphology was analysed by FE-SEM, and surface area analysis was performed. The surface acidities of the as-synthesized catalysts were elucidated by pyridine FTIR spectra and NH₃-TPD. The catalytic performance was thoroughly studied as a function of Zn²⁺ doping, reaction temperature, catalysts loading, and effect of solvents. Microwave-synthesized Zn₀.₅TPA/γ-Al₂O₃ exhibited excellent catalytic fructose dehydration, with 88% HMF yield at 120 °C for 2 h. The surface Brønsted acidity was found to be crucial for optimum catalytic activity.