Copper-boosted thiol-functionalized carbon nanospheres from biomass: a novel non-noble metal based recoverable catalyst for efficient nitro-to-amine reduction

Abstract

In this work, the synthesis and catalytic activity of thiol-functionalized copper-deposited porous carbon derived from dry oil palm leaves (Cu/TF-CNS) was investigated for the reduction of aromatic nitro compounds. The procedure to synthesize porous carbon nanospheres involves the pyrolysis of oil palm leaves in a nitrogen atmosphere at 1000 °C. The resulting porous carbon material was further functionalized with thiol groups to facilitate the uniform deposition of copper nanoparticles and serve as an efficient support. Excellent catalytic performance was shown by the Cu/TF-CNS catalyst in reducing aromatic nitro compounds to their corresponding aromatic amines with a low copper loading of only 4 mol% which is an inexpensive non-noble metal in the presence of NaBH₄ as a reducing agent and EtOH/H₂O as green solvents. The products were identified using ¹H NMR spectroscopy. The catalyst was isolated from the reaction mixture and reused upto 10 cycles without any significant loss in the activity. The ICPAES analysis confirmed the successful incorporation of approximately 8.9% Cu during the deposition process and the reusability of the catalyst underscores its efficacy as a sustainable and effective heterogeneous catalyst for nitroarene reduction.