CePO4, a multi-functional catalyst for carbohydrate biomass conversion: production of 5-hydroxymethylfurfural, 2,5-diformylfuran, and γ-valerolactone
Carbohydrates are considered as an economical and green source of energy; however, the high oxygen content present in carbohydrates makes them non-attractive as a fuel/fuel additives. Here, a simple multi-functional catalyst, CePO4, is presented for the efficient conversion of various carbohydrates (fructose, glucose, sucrose, and starch) into 5-hydroxymethylfurfural (HMF). To improve the catalytic activity of CePO4, especially for glucose and starch conversion, CePO4 is supported on the surface of an H-beta zeolite. CePO4 and CePO4 supported on the H-beta zeolite are thoroughly characterized using powder X-ray diffraction, N2-sorption, electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, pyridine adsorbed Fourier transform infrared spectroscopy, and NH3 temperature programmed desorption techniques. The carbohydrate to HMF conversion is demonstrated in a water–diglyme solvent mixture. Moreover, CePO4 exhibits very good activity for the selective oxidation of HMF to 2,5-diformylfuran in O2 at one atmospheric pressure under flow conditions. The catalytic activity of CePO4 is further explored for γ-valerolactone production from levulinic acid by using 2-propanol as the hydrogen source. One simple reusable CePO4 catalyst catalyzing three different reactions under different reaction conditions is interesting and certainly would attract industrial chemists and catalysis researchers.