Selective catalytic conversion of gamma-valerolactone to isopropyl valerate using MOF-derived Pd-ZrO 2 @C materials

Pd-containing zirconia nanomaterials have been prepared from MOFs (Metal-Organic Frameworks) as sacrificial template. MOFs (NH 2 -UiO-66(Zr)) was prepared by a solvothermal method and subsequently modified by a simple impregnation with a Pd salt. The resulting material was pyrolyzed at different temperatures under inert atmosphere in order to obtain ZrO 2 @C with different Pd contents. Materials have been fully characterized using several techniques including Xray diffraction (XRD), N 2 porosimetry and X-ray photoelectron spectroscopy (XPS), which pointed to the formation of ZrO 2 @C as well as Pd-ZrO 2 @C materials A notable feature across all synthesized materials was the strength of Lewis acid sites, imparting intrinsic activity to the catalyst. This, coupled with Pd as metal sites, resulted in a bifunctional catalyst. Synthesized materials were employed in the continuous flow hydrogenation of GVL (gamma-valerolactone) to isopropyl valerate, using 2-propanol as a solvent, reagent and H 2 donor. Reaction mechanism required the presence of metal sites (hydrogenation) and acid sites (ring opening), which makes the catalyst Pd-ZrO 2 @C highly promising for this reaction. These catalysts exhibited remarkable selectivity, exceeding 98% towards isopropyl valerate, while maintaining high conversion rates and displaying robust catalyst stability under flow conditions for up to 24 h.