Showing papers on "Nitrobenzene published in 2021"

Dual-atom Pt heterogeneous catalyst with excellent catalytic performances for the selective hydrogenation and epoxidation.

Abstract: Atomically monodispersed heterogeneous catalysts with uniform active sites and high atom utilization efficiency are ideal heterogeneous catalytic materials. Designing such type of catalysts, however, remains a formidable challenge. Herein, using a wet-chemical method, we successfully achieved a mesoporous graphitic carbon nitride (mpg-C3N4) supported dual-atom Pt2 catalyst, which exhibited excellent catalytic performance for the highly selective hydrogenation of nitrobenzene to aniline. The conversion of ˃99% is significantly superior to the corresponding values of mpg-C3N4-supported single Pt atoms and ultra-small Pt nanoparticles (~2 nm). First-principles calculations revealed that the excellent and unique catalytic performance of the Pt2 species originates from the facile H2 dissociation induced by the diatomic characteristics of Pt and the easy desorption of the aniline product. The produced Pt2/mpg-C3N4 samples are versatile and can be applied in catalyzing other important reactions, such as the selective hydrogenation of benzaldehyde and the epoxidation of styrene.

Single-atom Fe with Fe 1 N 3 structure showing superior performances for both hydrogenation and transfer hydrogenation of nitrobenzene

Abstract: The design of non-noble metal heterogeneous catalyst with superior performance for selective hydrogenation or transfer hydrogenation of nitroarenes to amines is significant but challenging. Herein, a single-atom Fe supported by nitrogen-doped carbon (Fe1/N-C) catalyst is reported. The Fe1/N-C sample shows superior performances for the selective hydrogenation and transfer hydrogenation of nitrobenzene to aniline at different temperatures. Density functional theory (DFT) calculations show that the superior catalytic activity for the selective hydrogenation at lower temperatures could be attributed to the effective activation of the reactant and intermediates by the Fe1/N-C. Moreover, the excellent performance of Fe1/N-C for the selective transfer hydrogenation could be attributed to that the reaction energy barrier for dehydrogenation of isopropanol can be overcome by elevated temperatures.

CuO as a reactive and reusable reagent for the hydrogenation of nitroarenes

Abstract: Copper oxide (CuO) is used as a reusable solid reagent for hydrogenation of nitroarenes to aminoarenes. The use of CuO resulted in 100 % conversion of 2.9 mmol of nitrobenzene to aniline in 45 s at room temperature using hydrazine hydrate as the reducing agent. During the reaction, CuO is converted to inactive metallic Cu which can be regenerated to active CuO by thermal oxidation. DFT simulations indicated facile formation of oxygen vacancies (EO,vac = −3.8 kJ/mol) on the surface of CuO (111) in reducing environment which is consistent with the XPS analysis. Oxygen vacancies facilitate stronger nitrobenzene binding (−148.5 kJ/mol) and reduced activation barrier (Ea = 36.4 kJ/mol) for N O dissociation. Motivated from this mechanistic insight -NO2 groups in various nitroarenes were selectively hydrogenated to NH2 groups using CuO.

Selective electrocatalytic hydrogenation of nitrobenzene over copper-platinum alloying catalysts: Experimental and theoretical studies

Abstract: We report ultrafine CuxPty alloying nanoparticles anchored on carbon black (CuxPty/C) for selective electrocatalytic hydrogenation of nitrobenzene (Ph-NO2) at ambient conditions. The experimental and theoretical studies reveal that as electrocatalyst, the optimal Cu3Pt/C with adjusted electronic structure can effectively facilitate the adsorption and activation of Ph-NO2. The results indicate that the acidic media is favorable for the production of aminobenzene irrelevant to the applied potential, while the electrocatalytic hydrogenation products are highly dependent on the reduction potential in the alkaline media. As a result, the Cu3Pt/C can afford almost 100 % conversion of Ph-NO2 into azoxybenzene with ∼99 % selectivity at 0.3 V (vs. RHE) and aminobenzene with ∼99 % selectivity at -0.3 V (vs. RHE) in 1.0 M KOH, respectively. The theoretical calculations provide a comprehensive understanding of the selective electrocatalytic hydrogenation mechanisms of Ph-NO2 relative to electrolyte pH and applied potential, matched well with the experimental results.

Monolayer Bi2W1–xMoxO6 Solid Solutions for Structural Polarity to Boost Photocatalytic Reduction of Nitrobenzene under Visible Light

Abstract: Monolayer nanosheets of Bi₂W₁–ₓMoₓO₆ solid solutions, possessing an average thickness of 0.98 nm, have been rationally designed and constructed by a facile bottom-up route of a hydrothermal reaction. The tiptop photocatalytic efficiency of Bi₂W₁–ₓMoₓO₆ monolayer nanosheets can be achieved for effective reduction conversion of nitrobenzene into anilines under visible light, in conspicuous contrast to the homologous pristine Bi₂WO₆ and Bi₂MoO₆ components. The optimal Bi₂W₀.₂₅Mo₀.₇₅O₆ monolayer nanosheets exhibit a high selectivity and stability for photocatalytic nitrobenzene reduction, affording a high aniline generating rate of 650 μmol g–¹.h–¹, in excess of the previously reported ordinary photocatalysts. The good photocatalytic property could be due to the lattice distortion in solid solutions for structural polarity by the more electronegative W substitution, leading to the efficient interfacial and interior separation of photogenerated carriers. The structure–activity relationship of Bi₂W₁–ₓMoₓO₆ demonstrates a novel insight to devise property-controllable photocatalysts at the atomic level with high efficiency for organic photocatalytic reactions.

Two-Dimensional Pd Nanosheets with Enhanced Catalytic Activity for Selective Hydrogenation of Nitrobenzene to Aniline

Abstract: Two-dimensional (2D) metallic Pd nanosheets were synthesized by an ion-exchange method using PdCl42– and magnesium- and aluminum-based metallic (LDH) as intercalation ion and host material, respect...

Detection of nitrobenzene using transition metal doped C24: A DFT study

Abstract: First principles calculations have been used to verify the ability for sensing nitrobenzene by the host systems, pristine C24 and transition metal (TM) doped C24, viz., C24+TM (TM = Sc, Cr and Mn). All the TM doped host systems are energetically stable which is confirmed from their negative values of binding energy. To get a clear view of the participation of the orbitals of different atoms of the host and how they are modified on the adsorption of nitrobenzene, density of states has been explored. Finally, charge transfer between the hosts and the guest is also calculated. Nitrobenzene is adsorbed on both pristine and TM doped C24 fullerene, but with reasonable adsorption energy and achievable recovery time, Sc doped C24 emerges as the best sensor device for sensing nitrobenzene among the TM doped fullerenes.

Silver chromate doped Ti-based metal organic framework: synthesis, characterization, and electrochemical and selective photocatalytic reduction properties

Abstract: Photo-induced reduction plays a remarkable role in the preparation of aniline from nitrobenzene. The challenges of this method are the selectivity of the products and irradiation sources. So, organic compound transformations induced by visible light have received enormous attention due to their lower cost, and better safety for environmental applications. Here, aniline compounds were prepared with Ag2CrO4, NH2-MIL-125, and Ag2CrO4@NH2-MIL-125 nanocatalysts. The Ag2CrO4@NH2-MIL-125 nanocatalysts were prepared by a controlled room temperature deposition technique. The effects of catalyst composition, time, and nitrobenzene concentration on reaction performance have been systematically elaborated. Under the ideal reaction setup, aniline with high yield was obtained from nitrobenzene, and the conversion percent of Ag2CrO4, NH2-MIL-125, and Ag2CrO4@NH2-MIL-125 was 22%, 48%, and 97.8%, respectively. The recycling of the photocatalyst showed excellent performance for five regenerations. The mechanism of the photoreduction process has been proposed based on the reactivity and kinetics of the reaction. The kinetic rate of Ag2CrO4, NH2-MIL-125, and Ag2CrO4@NH2-MIL-125 was 0.01603, 0.1416 and 0.5199 min−1, respectively. The electrochemical performance of the Ag2CrO4@NH2-MIL-125 nanocatalyst was studied. The cyclic voltammetry, charge–discharge performance of Ag2CrO4@NH2-MIL-125 were elaborated. Amazing improvement was shown in the performance of Ag2CrO4@NH2-MIL-125 compared to the original NH2-MIL-125. Additionally, Ag2CrO4@NH2-MIL-125 displayed a specific capacitance of 103.12 F g−1 at current density of 1 A g−1.

Cu–MnOX/γ-Al2O3 Catalyzed Ozonation of Nitrobenzene in a High-Gravity Rotating Packed Bed

Abstract: In this study, Cu–MnOX/γ-Al2O3 catalyst was first used for heterogeneous catalytic ozonation of nitrobenzene (NB) in a high-gravity rotating packed bed (RPB), as RPB could significantly improve the...

Highly porous copper-supported magnetic nanocatalysts: made of volcanic pumice textured by cellulose and applied for the reduction of nitrobenzene derivatives

Abstract: Herein, a novel designed heterogeneous catalytic system constructed of volcanic pumice magnetic particles (VPMPs), cellulose (CLS) as a natural polymeric matrix, and copper nanoparticles (Cu NPs) is presented. Also, to enhance the inherent magnetic property of VPMP, iron oxide (Fe3O4) nanoparticles have been prepared and incorporated in the structure via an in situ process. As its first and foremost excellent property, the designed composite is in great accordance with green chemistry principles because it contains natural ingredients. Another brilliant point in the architecture of the designed composite is the noticeable porosity of VPMP as the core of the composite structure (surface area: 84.473 m2 g−1). This great porosity leads to the use of a small amount (0.05 g) of the particles for catalytic purposes. However, the main characterization methods, such as Fourier-transform infrared and energy-dispersive X-ray spectroscopy, thermogravimetric analysis, and electron microscopy, revealed that the spherical metallic particles (Fe and Cu oxides) were successfully distributed onto the surface of the VPMP and CLS matrices. Further, vibrating-sample magnetometer analysis confirmed the enhancement of the magnetic property (1.5 emu g−1) of the composite through the addition of Fe3O4 nanoparticles. Further, the prepared (Fe3O4@VPMP/CLS–Cu) nanocomposite has been applied to facilitate the reduction reaction of hazardous nitrobenzene derivatives (NBDs) to their aniline analogs, with 98% conversion efficiency in eight minutes under mild conditions. Moreover, the good reusability of the catalytic system has been verified after recycling it ten times without any significant decrease in the performance.