Vacuum-Freeze Drying Assist for the Fabrication of a Nickel-Aluminium Catalyst and Its Effects on the Structure-Reactivity in the Catalytic Dry Reforming of Methane

A co-precipitation along with vacuum-freeze drying (VFD) method was applied to fabricate a highly mesoporous nickel-aluminum catalyst (VFD-cat). VFD-cat with uniform smaller pore size and a larger BET surface area were obtained than the catalysts prepared following the conventional thermal evaporation drying method (TED-cat). Also, the VFD method helped to improve the dispersion of precursors, which then enhanced the strong metal-support interactions (MSI) of VFD-cat via forming substoichiometric NiAl₂O₄ spinel. Characterization showed that the average nickel particle size on the VFD-cat was smaller than that of the TED-cat, attributed to the confinement effects of MSI. At 800°C, the VFD-cat exhibited higher stability during the long-term dry reforming of methane (DRM) test. Results revealed that the coke formation on spent VFD-cat, especially for the ordered carbon species, was significantly eliminated as compared with TED-cat after the stability test. This strategy offers a facile way to develop DRM catalysts with highly mesoporous and MSI, enhancing the catalytic stability and coke resistance of the nickel-aluminum catalyst.