Synergism of Pt single atoms, clusters and nanoparticles on carbon doping with nitrogen for nitroaromatics highly efficient and selective hydrogenation

Abstract

This work constructs a series of the Pt/NC catalysts with various Pt contents (0.22 wt%, 0.42 wt%, 1.08 wt%) via liquid-phase reduction method and their catalytic behaviors are systematically evaluated for heterogeneous catalytic hydrogenation of nitroarenes. The results show that 1.08% Pt/NC exhibits the most excellent catalytic performance: under quite mild conditions (30 °C, 1.0 MPa H2), it can efficiently convert nitrophenol within just 3 min (90.2% conversion), with nitro-group hydrogenation selectivity > 99% and the TOF of 5298.6 h-1, moreover, it has an extremely ultra-high TOF of 74191.8 h-1 in the hydrogenation reaction of nitrobenzene to aniline, showing ultra-high intrinsic activity. Additionally, using nitrobenzene selective hydrogenation as model reaction, the proposed reaction pathways are provided. Combining with Spherical Aberration Corrected-Transmission Electron Microscope (AC-STEM) and XPS characterizations, it can be known that Pt single atoms, clusters and nanoparticles are together loaded on the surface of nitrogen-doped carbon, and there is electron interaction between pyridinic nitrogen and Pt (electrons transferring from Pt to N). Compared with other catalysts, the electronic interaction between Pt and N in 1.08% Pt/NC is stronger, its adsorption capacity for hydrogen at Pt nanoparticles and clusters and -NO2 group at Pt single atoms via the interaction of of “Ptδ+---O=N” is much more superior, and it can greatly enhance the activity and selectivity of nitro-group hydrogenation.