Amphiphilic Mesoporous Sandwich-Structured Catalysts for Selective Hydrogenation of 4-Nitrostyrene in Water

Facile Transfer Hydrogenation of N-Heteroarenes and Nitroarenes Using Magnetically Recoverable Pd@SPIONs Catalyst

Catalysts with active, selective, and reusable features are desirable for sustainable development. The present investigation involved the synthesis and characterization of bear-surfaced ultrasmall Pd particles (<1 nm) loaded onto the surface of magnetic nanoparticles (8-10 nm). The amount of Pd loading onto the surface of magnetite is recorded as 2.8 wt %. The characterization process covered the utilization of scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), inductively coupled plasma (ICP), and X-ray photoelectron spectroscopy (XPS) methods. The Pd@Fe3O4 catalyst has shown remarkable efficacy in the hydrogenation of quinoline, resulting in the production of >99% N-ring hydrogenated (py-THQ) product. Additionally, the catalyst facilitated the conversion of nitroarenes into their corresponding aniline derivatives, where hydrogen was achieved by H2O molecules with the aid of tetrahydroxydiboron (THDB) as an equilibrium supportive at 80 °C in 1 h. The high efficiency of a transfer hydrogenation catalyst is closely related to the metal-support synergistic effect. The broader scope of functional group tolerance is evaluated. The potential mechanism underlying the hydrogenation process has been elucidated through the utilization of isotopic labeling investigations. The application of the heterocyclic compound hydrogenation reaction is extended to formulate the medicinally important tubular polymerization inhibitor drug synthesis. The investigation of the recyclability of Pd@Fe3O4 has been conducted.

Ru-Ni Alloy Nanoparticles Loaded on N-Doped Amphiphilic Mesoporous Hollow Carbon@silica Spheres as Catalyst for the Hydrogenation of α-Pinene to cis-Pinane

N-doped mesoporous carbon spheres (NHMC@mSiO₂ ) encapsulated in silica shells were prepared by emulsion polymerization and domain-limited carbonization using ethylenediamine as the nitrogen source, and Ru-Ni alloy catalysts were prepared for the hydrogenation of α-pinene in the aqueous phase. The internal cavities of this nanomaterial are lipophilic, enhancing mass transfer and enrichment of the reactants, and the hydrophilic silica shell enhances the dispersion of the catalyst in water. N-doping allows more catalytically active metal particles to be anchored to the amphiphilic carrier, enhancing its catalytic activity and stability. In addition, a synergistic effect between Ru and Ni significantly enhances the catalytic activity. The factors influencing the hydrogenation of α-pinene were investigated, and the optimum reaction conditions were determined to be as follows: 100 °C, 1.0 MPa H₂ , 3 h. The high stability and recyclability of the Ru-Ni alloy catalyst were demonstrated through cycling experiments.

High-Performance Heterogeneous Thermocatalysis Caused by Catalyst Wettability Regulation

Catalyst wettability regulation has emerged as an attractive approach for high catalytic performance for the past few years. By introducing appropriate wettability, the molecule diffusion of reactants and products can be enhanced, leading to high activity. Besides this, undesired molecules are isolated for high selectivity of target products and long-term stability of catalyst. Herein, we summarize wettability-induced high-performance heterogeneous thermocatalysis in recent years, including hydrophilicity, hydrophobicity, hybrid hydrophilicity-hydrophobicity, amphiphilicity, and superaerophilicity. Relevant reactions are further classified and described according to the reason for the performance improvement. It should be pointed out that studies of utilizing superaerophilicity to improve heterogeneous thermocatalytic performance have been included for the first time, so this is a comparatively comprehensive review in this field as yet.

Highly Efficient and Chemoselective Hydrogenation of Nitro Compounds into Amines by Nitrogen-Doped Porous Carbon-Supported Co/Ni Bimetallic Nanoparticles

A novel Co/Ni bimetallic nanoparticle supported by nitrogen-doped porous carbon (NPC), Co₅/Ni@NPC-700, exhibits high conversion, chemoselectivity, and recyclability in the hydrogenation of 16 different nitro compounds into desired amines with hydrazine hydrate under mild conditions. The synergistic effects of Co/Ni bimetal nanoparticles and the NPC-supported porous honeycomb structure with more accessible active sites may be responsible for the high catalytic hydrogenation performance.

Morphological and reactive optimization of g-C3N4-derived Co,N-codoped carbon nanotubes for hydrogen evolution reaction

Scheme for the synthesis of bamboo-like N-doped carbon nanotubes.

Pt nanoparticles on Ti3C2Tx-based MXenes as efficient catalysts for the selective hydrogenation of nitroaromatic compounds to amines

The development of Pt nanocatalysts for the selective hydrogenation of nitroaromatic compounds to the corresponding amines is of great significance to solve the drawbacks associated with a low reserve of Pt. Herein, we develop a protocol for the preparation of a Pt/titanium carbide-based MXene heterostructure for the selective reduction of nitroaromatic compounds. In the heterostructure, well-defined and nano-sized metallic Pt crystallites are uniformly decorated on Ti3C2Tx nanosheets using a mild reducing agent of ammonia borane without additional stabilizing agents. The selective hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN) was employed as a model reaction to investigate the catalytic performance of the as-synthesized heterostructure, denoted as Pt/Ti3C2Tx-D-AB. Notably, this catalyst can catalyze the complete conversion of p-CNB to p-CAN with 99.5% selectivity, superior to that of Pt/Ti3C2Tx-D-SB synthesized with sodium borohydride. The high performance of the present catalytic system can be ascribed to the well-dispersed Pt nanoparticles, the abundant surface electron-efficient Pt(0), and the synergistic catalysis between Pt/Ti3C2Tx-D-AB and water. This catalyst also shows generality toward the selective hydrogenation of a series of nitroaromatic compounds to the corresponding amines with high efficiency. The present study provides a strategy to synthesize efficient catalysts for catalytic applications.