ju Chen

Highly chemoselective reduction of nitroarenes over non-noble metal nickel-molybdenum oxide catalysts

The chemoselective reduction of nitroarenes is an important transformation for the production of arylamines, which are the primary intermediates in the synthesis of pharmaceuticals, agrochemicals and dyes. Heterogeneous non-noble metal nickel-molybdenum oxide catalysts supported on ordered mesoporous silica SBA-15 (Ni-MoO3/CN@SBA-15) were prepared for the first time by treating SBA-15-supported nickel-molybdenum oxide materials with 1,10-phenanthroline, and exhibited unprecedented catalytic activity and chemoselectivity for the reduction of various substituted nitroarenes to the corresponding aromatic amines in ethanol with hydrazine hydrate as a hydrogen donor under mild conditions owing to the synergistic effect of metal Ni and MoO3 species, affording excellent yields of >99% within very short reaction periods (≤60 min). The Ni-MoO3/CN@SBA-15 catalysts were highly stable and could easily be recovered by simple filtration or by an external magnetic field for at least ten recycling reactions without any observable loss of catalytic performance or leaching of metal components.

Solvent-Free Selective Hydrogenation of Nitroarenes Using Nanoclusters of Palladium Supported on Nitrogen-Doped Ordered Mesoporous Carbon

The selective hydrogenation of nitroarenes is a key transformation for the production of aromatic amines, which are primary intermediates in the synthesis of pharmaceuticals, agrochemicals, and dyes. However, most reaction processes require toxic organic solvents and suffer from poor selectivity in the presence of other reducible groups. Herein, we report a successful example of nanoclusters of ultrafine Pd supported on N‐modified ordered mesoporous CMK‐3 carbon (Pd/N‐CMK‐3) prepared by a facile two‐step impregnation route with aqueous solutions of 1,10‐phenanthroline and H2PdCl4 that hydrogenated various nitroarenes highly efficiently and selectively to the corresponding aromatic amines with hydrogen in the absence of solvent. The Pd/N‐CMK‐3 catalyst could be recovered easily for multiple recycling reactions without a loss of catalytic performance.

Nitrogen-doped graphene-activated metallic nanoparticle-incorporated ordered mesoporous carbon nanocomposites for the hydrogenation of nitroarenes

Herein, nanoscale metallic nanoparticle-incorporated ordered mesoporous carbon catalysts activated by nitrogen-doped graphene (NGr) were fabricated via an efficient multi-component co-assembly of a phenolic resin, nitrate, acetylacetone, the nitrogen-containing compound 1,10-phenanthroline, and Pluronic F127, followed by carbonization. The obtained well-dispersed nitrogen-doped graphene-activated transition metal nanocatalysts possess a 2-D hexagonally arranged pore structure with a high surface area (∼500 m2 g−1) and uniform pore size (∼4.0 nm) and show excellent activity for the selective hydrogenation–reduction of substituted nitroarenes to anilines in an environmentally friendly aqueous solution. The high catalytic performance and durability is attributed to the synergistic effects among the components, the unique structure of the nitrogen-doped graphene layer-coated metallic nanoparticles, and electronic activation of the doped nitrogen.

Investigation of mesoporous NiAl2O4/MOx (M = La, Ce, Ca, Mg)–γ-Al2O3 nanocomposites for dry reforming of methane

One-pot synthesized mesoporous NiAl2O4/γ-Al2O3 and NiAl2O4/MOx (M = La, Ce, Ca, Mg)–γ-Al2O3 nanocomposites with excellent textural properties were employed for the dry reforming of methane (DRM). NiAl2O4/La2O3/γ-Al2O3-imp prepared via a traditional impregnation method was used for comparison. The promotion effect of modifiers on the physicochemical properties and catalytic performance of the catalysts was systematically investigated. Characterization and evaluation results indicated that the modified catalysts showed higher activities and better coking-resistance than Ni/γ-Al2O3, and Ni/La2O3–γ-Al2O3 was found to be the most effective one. All the catalysts with or without modifiers presented similar Ni particle sizes due to the enhanced metal–support interaction derived from the reduction of the NiAl2O4 precursor. However, more medium-strength basic sites on the catalyst surface were obtained by adding promoters, which could facilitate the adsorption/activation of CO2 and the gasification of amorphous carbon, improving the catalytic properties and accelerating the coke elimination rate. Additionally, the incorporation of promoters also prevented the phase transformation of γ-alumina.