Mesoporous ZrO₂ Nanoframes for Biomass Upgrading

The rational design and preparation of a high-performance catalyst for biomass upgrading are of great significance and remain a great challenge. In this work, mesoporous ZrO₂ nanoframe, hollow ring, sphere, and core-shell nanostructures have been developed through a surfactant-free route for upgrading biomass acids into liquid alkane fuels. The obtained ZrO₂ nanostructures possess well-defined hollow features, high surface areas, and mesopores. The diversity of the resultant ZrO₂ nanostructures should arise from the discrepant hydrolysis of two different ligands in zirconocene dichloride (Cp₂ZrCl₂) as the zirconium precursor. The time-dependent experiments indicate that Ostwald ripening and salt-crystal-template formation mechanisms should account for hollow spheres and nanoframes, respectively. Impressively, compared with the hollow sphere, commercial nanoparticle, and the ever-reported typical results, the ZrO₂ nanoframe-promoted Ni catalyst exhibits greatly enhanced catalytic activity in the upgrading of biomass acids to liquid alkane fuels, which should be ascribed to the hollow feature, large active surface area, highly dispersed Ni, and strong metal-support interactions arising from the structural advantages of nanoframes. The nanoframes also possess excellent solvothermal and thermal stability. Our findings here can be expected to offer new perspectives in material chemistry and ZrO₂-based catalytic and other applications.