Selective Hydrodeoxygenation of 5‑Hydroxymethylfurfural to 2,5-Dimethylfuran over Ni Supported on Zirconium Phosphate Catalysts

Crystal α-zirconium phosphate (α-ZrP) was prepared by a hydrothermal method and exfoliated into a layered structure by n-hexylamine (C6H13NH2). Ni-based catalyst (Ni/ZrP) was promoted by loading nickel on the layered α-ZrP via ion exchange. The catalyst was performed to catalyze hydrodeoxygenation of 5-hydroxymethylfurfural (HMF) to 2,5-dimethylfuran (DMF), and a 68.1% yield of DMF and 100% conversion of HMF were achieved at 240 °C, 5 MPa H2, and 20 h. The DMF yield can still retain 52.8% after five cycles. The characteristics of the catalyst were investigated via N2 adsorption–desorption, X-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy, pyridine-adsorbed Fourier transform infrared (FTIR) spectra, FTIR spectra, inductively coupled plasma mass spectrometry, and thermogravimetric analysis–mass spectrometry, as well as Raman spectroscopy. A pathway from HMF to DMF was found with MF as the intermediate product, and DMF production was preferable via the −CH2OH group hydrogenolysis of HMF over Lewis acidic sites of Ni/ZrP, which is caused by the zirconium vacant orbits.