Highly dispersed platinum and phosphomolybdic acid (PMo) on the UiO-66 metal–organic framework (MOF) for highly efficient and selective hydrogenation of nitroaromatics

Abstract

Pt-PMo@UiO-66 catalysts synthesized via a solvothermal method utilizing phosphomolybdic acid as a stabilizing agent exhibit exceptional catalytic performance in the selective hydrogenation of nitroarenes. The nanostructure of the Pt-PMo@UiO-66 catalysts is demonstrated by ICP-OES, XRD, XPS, TEM, HRTEM, STEM-EDS and other characterization studies. The Pt nanoparticles (NPs) or clusters are mainly supported on the surface of UiO-66. There is a synergistic catalytic effect between Pt, phosphomolybdic acid and UiO-66, improving their catalytic hydrogenation performance (activity, selectivity and stability) for nitroarene hydrogenation. It is found that 0.32%Pt-PMo@UiO-66 has the best catalytic properties for nitroacetophenone hydrogenation, with 98.8% conversion and 99.6% selectivity to aminoacetophenone under relatively mild reaction conditions (1.75 h, 40 °C, 3.0 MPa H₂). The turnover frequency (TOF) reaches 1498.0 h⁻¹. The catalyst also shows high selectivity for the hydrogenation of halogen-containing nitroarenes without dehalogenation. The appropriate size of the Pt NPs (4.44 nm) and the electronic effect (electron transfer from Pt to Mo) improves the catalytic hydrogenation activity and selectivity of Pt-PMo@UiO-66 for the selective hydrogenation of nitroarenes under moderate reaction conditions.