ZrO(OH)<sub>2</sub>/Zn-MOF as a Nanocatalyst for Visible-Light-Driven\nSynthesis of Levulinic Acid from 5‑Hydroxymethylfurfural

The organic transformation requires efficient and durable\ncatalysts\nto drive reactions with high selectivity and efficiency. Herein, we\ndemonstrate the postfunctionalization of a Zn-metal–organic\nframework (Zn-MOF), derived from trimesic acid building units, with\nzirconyl hydroxide to produce a nanocatalyst ZrO(OH)<sub>2</sub>/Zn-MOF.\nThe parent nanomaterial Zn-MOF is constituted by Zn(II) octahedra\naligned parallelly to form a highly porous two-dimensional (2D) paddle-wheel\nnetwork with dual pores of size 6.41 and 9.60 nm. The porosity of\nthe nanomaterial allows Zr(IV) moieties (size ranging from 2.5 to\n3 nm) to percolate and occupy the vacant spaces. Fourier transform\ninfrared (FTIR), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller\n(BET) analysis, field emission scanning electron microscopy (FESEM),\nhigh-resolution transmission electron microscopy (HRTEM), powder X-ray\ndiffraction (PXRD), inductively coupled plasma mass spectrometry (ICP-MS),\ntemperature-programmed desorption (TPD), and X-ray photoelectron spectroscopy\n(XPS) confirm the formation of ZrO(OH)<sub>2</sub>/Zn-MOF with sufficient\nporosity, thermal stability, and crystallinity. The hydrated form\nof zirconia (ZrO(OH)<sub>2</sub>) provides the active sites for the\nphotocatalytic conversion of levulinic acid to 5-hydroxymethylfurfural\nvia acid-catalyzed hydrolysis. The ZrO(OH)<sub>2</sub>/Zn-MOF catalyzes\nthe conversion when irradiated with visible light at room temperature\nyielding >99% of levulinic acid in 2 h. The selective formation\nof\nlevulinic acid has been verified by NMR spectroscopy and high-performance\nliquid chromatography (HPLC-PDA). The reaction kinetics and mechanism\nare also confirmed by density functional theory (DFT) studies. The\ncatalyst exhibits excellent efficiency, stability, and reusability\nwithout any oligomerization over multiple cycles.