Ni-based nanocatalyst protected by ultrathin mesoporous nitrogen-doped carbon layer with hollow structure for the efficient transfer hydrogenation of halogenated nitrobenzenes

It is of great scientific and industrial value to develop cheap and efficient supported non-noble metal-based catalysts for the selective hydrogenation of halogenated nitrobenzenes. In this work, hollow-structured Ni-based nano-catalysts coated with ultrathin nitrogen-doped carbon layers (H-Ni@NC) have been prepared. The etching of SiO2 template before calcination and decomposition of residual Ni3Si2O5(OH)4 shell into SiO2 leads to the resulting catalysts could maintain good mechanical property and stability. The H-Ni@NC catalyst prepared at 600 °C exhibits the optimal catalytic performance for the catalytic selective hydrogenation of halogenated nitrobenzenes under mild conditions (60 °C) when using hydrazine hydrate (N2H4·H2O) as the reducing agent, and could maintain its catalytic properties even after 5 consecutive runs. The contrast experiments confirm that the combination of hollow structure with N-doped carbon protective layer make the catalyst show the best catalytic effect, and the synergistic effects are further discussed in detail combined with characterization analysis. In addition, this work further reveals the mechanism of Ni-based catalysts for the transfer hydrogenation of halogenated nitrobenzenes, which may provide a reference idea for the preparation of other Ni-based catalysts.