Hydrogenation of Nitrophenol via Nickel-Based Catalytic Membranes with Engineered Surface Affinity

Selective hydrogenation of nitro groups to amino groups is a crucial reaction in industries, with the hydrogenation of p-nitrophenol (PNP) to p-aminophenol (PAP) being a key step in the production of fine chemicals and environmental pollution mitigation. Conventional catalysts often suffer from nanoparticle agglomeration and poor separation, limiting their efficiency. Here, we developed Ni-based catalytic membranes derived from metal-organic frameworks (MOFs) with -NH₂ groups to enhance catalytic performance and stability. The Ni/CMs were prepared by growing Ni-based precursors in situ on ceramic membranes (CMs) via hydrothermal synthesis and pyrolysis. Among three different Ni/CMs, Ni/CM-ABDC, using 2-aminobenzene dicarboxylic acid (ABDC) as the ligand, exhibited the highest catalytic activity, achieving the PNP reduction rate of 14.3 h^-1 and its complete conversion in 90 min and maintaining high stability over five reaction cycles. This was due to the uniform dispersion of Ni nanoparticles (Ni NPs), the mesoporous N-doped carbon matrix, and the highest Ni⁰/Ni²⁺ ratio. In contrast, Ni/CM-Urea and Ni/CM-BDC showed inferior performance. Mechanistic studies revealed that the N-doped carbon matrix enhanced selective adsorption of PNP and desorption of PAP, promoting the hydrogenation process. This work demonstrates the potential of MOF-derived Ni/CMs for efficient hydrogenation of nitro-groups.