Engineering the Structure of ZIF-Derived Hierarchically Porous CoZn Catalysts for Efficient Selective Hydrogenation of Nitroarenes

Abstract

ZIF-derived metal/carbon materials have received great attention for heterogeneous catalysis because of their versatile tunability; however, most of them are microporousdominated structures, seriously limiting their catalytic performance. Herein, we directly synthesized CoZn@CN catalysts with high specific surface area and pore volume via the facile pyrolysis of CoZn-ZIF/g-C 3 N 4 @PDA composites (g-C 3 N 4 , graphitic carbon nitride; PDA, polydopamine), in which g-C 3 N 4 works as the poreforming agent and template and PDA mainly functions as the carbon source. The optimal catalyst (Co 4 Zn 2 @CN) exhibits superior specific surface area (825.0 m 2 /g) and pore volume (2.4 cm 3 /g), which can remarkably improve the mass transfer efficiency and boost the active site exposure, achieving a TOF of 34.5 h −1 for the selective hydrogenation of 3-nitrostyrene at 80 °C and 1 MPa H 2 . Additionally, the preferential adsorption of the nitro group is confirmed to be the main reason for the general selectivity in the hydrogenation of various functionalized nitroarenes. Finally, the Co 4 Zn 2 @CN catalyst also shows excellent stability and can be reused at least 5 times. We anticipate that such a novel strategy may provide some valuable insights into the synthesis of ZIF-derived catalysts with tunable structures.

Adsorption-Dependent H2O Effect for Nitrobenzene Hydrogenation to Aniline over Pt and Ni Catalysts

“…Corma et al have proposed a new deoxygenation path (Scheme S1) on the oxophilic metal Ni catalyst, in which the oxophilic character of Ni strongly facilitates the rupture of the N–O bond, in difference to Pt-based catalysts . To date, heterogeneous catalysts based on supported noble metals like Pt, Pd, or Ru, and non-noble metals like Ni or Co have been identified as effective active centers for nitroarenes reduction, though displaying distinct reaction mechanisms among catalysts. − …”