Stabilization of Pt nanoparticles within MOFs for selective hydrogenation of hazardous 4-nitrophenol to valuable 4-aminophenol: Confinement and synergistic effect

Abstract

Precious metal nanoparticles (NPs) are a kind of promising hydrogenation catalyst. However, the particle size, stabilization and uniform dispersion of precious metal NPs is always a great challenge. Herein, Pt NPs were synthesized with controlled particle size and uniformly confined within the pores of Fe-BDC MOFs via an eco-friendly polyol reduction method and evaluated for selective hydrogenation of 4-Nitrophenols (4-NiPh) to 4-Aminophenols (4-AmPh). Metal-Organic Frameworks (MOF), a promising host material, provide a large surface area and pore volumes for evenly accommodating the Pt NPs with controlled particle size. The as-prepared Pt/Fe-BDC catalyst exhibited higher catalytic hydrogenation activity under mild conditions. Interestingly, the Pt/Fe-BDC catalyst exhibited superior catalytic activity with low Pt loading (0.47%) than that of the Pt/Fe3O4 catalyst. A series of bulk and surface structural characterizations including XRD, FTIR, TEM, XPS and CO-FTIR, etc., were conducted to examine the outstanding performance of the Pt/Fe-BDC catalyst. The outstanding catalytic hydrogenation performance of Pt/Fe-BDC catalyst was attributed to the large surface area, pore volume and additional functional groups of MOFs. The large surface area and pore volume of Fe-BDC MOFs control the Pt particle size (1.9 ​nm), and high uniform dispersion (59%) due to confinement effect, while the presence of additional functional groups in Fe-BDC MOFs synergistically interacts with Pt species to generate more exposed surface active metallic Pt0.