posted on 2024-02-08, 15:41authored byGuilong Lu, Philipp Schwiderowski, Zewen Shen, Xiaoyu Li, Jonas Schulwitz, Baoxiang Peng, Guixia Zhao, Xiubing Huang, Martin Muhler
Transition metal and nitrogen codecorated carbon materials
have
recently emerged as robust and efficient heterogeneous catalysts because
of their unique electronic structure, superior activity, and high
metal utilization. The most popular synthetic strategy for those catalysts
is the direct pyrolysis of C- and N-containing precursors and metal
salts, but the obtained products often suffer from structural heterogeneity
of the active metal sites and poor mass transport. Herein, a hard
template-assisted metal coordinated polymer is developed to synthesize
a series of three-dimensional (3D) M-600-X (M = Fe,
Co, Ni, Cu; X = 700, 800, 900 °C) catalysts
with an advanced trimodal pore structure via a well-controlled two-step
pyrolysis. Due to a preliminary annealing at 600 °C, it is possible
to control the coordination configuration of the M–Nx moiety and the metal speciation by regulating the
subsequent pyrolysis temperature. The 3D Fe-600-800 catalyst exhibited
excellent catalytic performance in the oxidative coupling of benzylamine
under solvent-free conditions due to the active Fe–N3 moiety as well as the synergy between the atomic Fe sites and the
Fe/Fe3C nanoparticles. Moreover, this synthetic approach
can also be employed in gram-scale production, and the obtained catalysts
still possess superior activity and favorable stability, even in large-scale
imine production. Thus, this work enables the rational design of cost-effective
carbon-supported transition metal-based catalysts for highly efficient
organic transformation.