Turning the Structure and HMF Hydrogenation Activity of Ni-PS Catalyst via Calcination Temperature

A series of nickel phyllosilicate catalysts (Ni-PS-T, where T represents the calcination temperature in °C) were synthesized via he ammonia-evaporation method and calcined at different temperatures to investigate their performance in the hydrogenation of 5-hydroxymethylfurfural (HMF). Characterization by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) revealed that increasing the calcination temperature (300–1100 °C) triggered a phase evolution from the 1:1-type (tetrahedral-octahedral) to the 2:1-type (tetrahedral-octahedral-tetrahedral) Ni-PS, eventually leading to phase separation into NiO and SiO2. The content of the 2:1-type crystalline phase, H2 adsorption capacity, and C=O hydrogenation activity of HMF all exhibited a volcano-shaped trend with calcination temperature. Under the conditions of 100 °C and 2.5 MPa H2, Ni-PS-800 enabled HMF hydrogenation with a conversion of 90% and a selectivity of 84% to 2,5-dihydroxymethylfuran (DHMF), in which the catalyst exhibited good stability during five consecutive HMF hydrogenation cycles. The enhanced catalytic performance of Ni-PS-800 is attributed to its high 2:1-type phase fraction, which promotes a pronounced hydrogen-spillover effect and significantly enhances the intrinsic activity for C=O hydrogenation.