Highly active and selective Pd/g-C3N4 catalysts for nitroaromatics hydrogenation under mild reaction conditions

Graphitic carbon nitride (g-C 3 N 4 ) is prepared by high-temperature annealing method, followed by the deposition of noble metal (Pt, Rh, Pd, Ru) nanoparticles and then variants 0.38 wt%, 0.76 wt%, 2.51 wt%Pd/g-C 3 N 4 catalysts are obtained using NaBH 4 reduction method. Pd/g-C 3 N 4 exhibits excellent catalytic activity in nitroarenes selective hydrogenation under quite moderate reaction conditions (e.g., p-nitroacetophenone hydrogenation, 96.5 % conversion with 100 % selectivity to p-aminoacetophenone and 15.6 min −1 -turnover frequency at 3.0 MPa H 2 , 20 °C, 0.33 h). Additionally, the Pd/g-C 3 N 4 samples are used for 1, 3-dinitrobenzene hydrogenation, 2.51 wt%Pd/g-C 3 N 4 obtains 97.6 % conversion and 100 % selectivity to m-nitroaniline (20 °C, 3.0 MPa H 2 , 1 min). TOF: 2.51 wt%Pd/g-C 3 N 4 -2.02 s −1  > 0.76 wt%Pd/g-C 3 N 4 -0.56 s −1  > 0.38 wt%Pd/g-C 3 N 4 -0.54 s −1 for 1, 3-dinitrobenzene hydrogenation. Characterizations of XRD, XPS, AC-STEM, AC-STEM elemental analysis, TEM, HRTEM, BET and H 2 -TPD, etc. demonstrate that the Pd nanoparticles in Pd/g-C 3 N 4 have high dispersion and surface/interface synergy of Pd-g-C 3 N 4 , probably contributing to the catalyst's enhanced selectivity, activity, and stability in nitroaromatics hydrogenation. In addition, the catalyst is recyclable and highly durable for nitroaromatics hydrogenation.