Low-coordinated platinum material for hydrogenation of m-dinitrobenzene to m-phenylenediamine

Abstract

Catalytic hydrogenation of aromatic nitro-compounds to corresponding aromatic amines is an environmental-friendly transformation for the production of dyes and pigments in industrial. Herein, an efficient low-coordinated Pt derived from Ni-Pt alloy archored on silica has been fabricated via dealloying process. Transmission electron microscopy (TEM) analysis confirmed an equivalent metal particle size to the reference dense Pt. Additionally, the characterizations revealed that the generation of unsaturated coordination in the resultant material leads to enhanced active surface area, increased fraction of low-coordinated and electron-enriched Pt. The as-prepared low-coordinated Pt catalyst was applied for liquid-phase m-dinitrobenzene (m-DNB) hydrogenation. Under the reaction conditions of ambient temperature, atmospheric pressure and m-DNB/Pt molar ratio of 140, both the m-DNB conversion and the selectivity to m-phenylenediamine (m-PDA) reached 99% within 2 h, superior to those observed over the reference dense Pt and the reported Pt-based catalysts. The enhanced catalytic properties were attributed to the promotional effect of unsaturated coordinated structure, which provided more Pt active sites with low coordination number and high electron density. This study demonstrates the importance of unsaturated coordination in metallic catalysts and establishes a powerful protocol for the design of an effective metal catalyst for the hydrogenation of a range of nitroaromatic compounds.