Highly Dispersed Palladium Nanoparticles on Carbon Doping with Nitrogen Derived from MOFs for 4-Nitrophenol Hydrogenation

Abstract

A series of the Pd/NC samples with various Pd loadings (0.11%, 0.48%, and 2.52%) are prepared via sodium borohydride (NaBH₄) reduction method and carbon doping with nitrogen (NC) is acquired by the pyrolysis of ZIF-8. The samples are characterized by XRD, BET, SEM, TEM, HRTEM, STEM-EDX elemental maps and line-scanning, XPS, TG, and so forth. It confirms that the Pd nanoparticles (NPs) are successfully coated on the NC. The catalytic behaviors of the samples are evaluated by the hydrogenation of 4-nitrophenol (4-NP), the 2.52%Pd/NC catalyst shows the best catalytic property among as-obtained catalysts maybe due to the much more Pd(0) species. The 2.52%Pd/NC catalyst exhibits 100% selectivity to 4-aminophenol (4-AP) at high conversion of 4-nitrophenol and 321.8 h⁻¹ turnover frequency (TOF) under mild reaction conditions (3.0 MPa H₂, 40 °C, 1 h). Moreover, the catalysts show an excellent stability.