Polyol-Made Sustainable Platinum Nanoparticles Encaged within Metal-Organic Frameworks for Promoted Selective Hydrogenation of Furfural to Furfural Alcohols

As a result of the high surface energy, noble metal nanoparticles (NPs) tend to agglomerate and destabilize during catalytic reactions and, hence, proved uneconomical, which is not conducive to improved activity. Therefore, the sustainable reduction and stabilization of precious metal NPs are highly demanded to achieve high activity. Herein, Pt NPs were encaged within metal-organic frameworks (MOFs) using polyols [polyvinylpyrrolidone (PVP), ethylene glycol (EG), and polyethylene glycol (PEG)] as reductants and stabilizers. In comparison to Pt/MOF(EG) and Pt/MOF(PVP), the Pt/MOF(PEG) catalyst exhibits remarkable activity in the selective hydrogenation of furfural (FFL) to furfural alcohol (FOL), which was attributed to electron-rich Pt (Pt⁰). The X-ray photoelectron spectroscopy (XPS) and carbon monoxide Fourier transform infrared spectroscopy (CO-FTIR) analyses confirmed the existence of more exposed Pt⁰ entities in Pt/MOF(PEG), and they support the hypothesis that the valence electrons of oxygen of the hydroxyl group (OH) present in PEG molecules more intensely interact by providing the coordinated saturation of dangling bonds on the Pt NP surface. Hence, the electron-populated Pt NPs (Pt⁰) possess sufficiently exposed active sites that distinctly improve selective activation and hydrogenation (≥90%) of the carbonyl bond (C═O) present in α,β-unsaturated aldehydes (UALs). Besides, the Pt/MOF(PEG) catalyst exhibited outstanding durability and recyclability for up to 5 consecutive rounds, validating its real-world applicability.