Enhanced Catalytic Performance for Hydrogenation of Substituted Nitroaromatics over Ir-Based Bimetallic Nanocatalysts

Abstract

IrM (M = Fe, Co, and Ni) alloy nanoparticles (NPs) were synthesized in a solution by employing butyllithium as a reduction agent and oleylamine as a stabilizing agent, and the alumina-supported IrM bimetallic nanoparticles were tested for selective hydrogenation of various substituted nitroaromatics. The relevant characterizations including X-ray diffraction, X-ray photoelectron spectra, transmission electron microscopy, and diffuse reflectance fourier transform infrared with CO probes confirm that IrM NPs are uniform alloys. The obtained IrM/Al 2 O 3 catalysts show significantly enhanced catalytic activity as well as selectivity relative to individual monometallic Ir catalysts, indicating a unique catalytic property of bimetallic alloy nanostructures. Among these bimetallic catalysts, IrNi/Al 2 O 3 illustrate the highest activity and selectivity for hydrogenation of various substituted nitroaromatics. Calculations by density functional theory suggest that bimetallic structures of IrNi facilitate the reactant adsorption and product desorption, resulting in enhanced catalytic performance.

Oxidative N-Formylation of Secondary Amines Catalyzed by Reusable Bimetallic AuPd–Fe3O4 Nanoparticles

“…With 2.8 mol% of Au–Fe 3 O 4 (entry 1) or 2.8 mol% of Pd–Fe 3 O 4 (entry 2), the reactions of secondary amines showed lower yields than those using AuPd–Fe 3 O 4 (entry 4). These results indicate that both Au and Pd within the alloy catalyst contribute to product formation through a synergistic effect [ 82 , 83 , 84 , 85 , 86 ]. When we used 1.4 mol% each of both Au–Fe 3 O 4 and Pd–Fe 3 O 4 , interestingly the reaction of N -methyl-1-phenylmethanamine afforded 90% yield of the desired product (entry 3).…”

In Situ Synthesized Silica‐Supported Co@N‐Doped Carbon as Highly Efficient and Reusable Catalysts for Selective Reduction of Halogenated Nitroaromatics

“…The halogenated anilines were an important group of key intermediates and raw materials in the pharmaceutical industry, such as chlorfluazuron and hexaflumuron . However, over traditional noble metal catalysts the selective reduction of the halogenated nitro aromatics to the halogenated anilines always made some unwanted dehalogenated side‐products which are difficult to separate, seriously reducing the product quality …”

“…The halogenated anilines were an important group of key intermediates and raw materials in the pharmaceutical industry, such as chlorfluazuron and hexaflumuron. [52][53][54] However, over traditional noble metal catalysts the selective reduction of the halogenated nitro aromatics to the halogenated anilines always made some unwanted dehalogenated side-products which are difficult to separate, seriously reducing the product quality. [55][56][57] The reductions of some representative halogen-substituted nitro aromatics were examined over the Co@CN/SiO 2 -500 catalyst using hydrazine hydrate and the results are given in Table 4.…”

Recent Advances in Hydrogenation Reactions Using Bimetallic Nanocatalysts: A Review

“…The PdÀ Au/TiO 2 catalyst could be recycled 5 times without much effect on yields. Hongbo Yu et al [26] also carried out the same reaction but applied it to fewer nitro compounds as compared to Bhairi Lakshminarayana and co-workers. [145] The reaction was carried out using IrÀ Ni/Al 2 O 3 , IrÀ Co/Al 2 O 3 , IrÀ Fe/ Al 2 O 3 of which IrÀ Ni/Al 2 O 3 gave the best results.…”