Showing papers on "Nitrobenzene published in 2019"
TL;DR: In this article, an alumina-supported bimetallic Fe-Cu catalysts were synthesized using a sol-gel method and exhibited high performance in catalytic degradation of nitrobenzene (NB).
Abstract: De-nitrogen of organic contaminants in industrial wastewater is a great challenge for environmental remediation. In this work, alumina-supported bimetallic Fe-Cu catalysts were synthesized using a sol-gel method and exhibited high performance in catalytic degradation of nitrobenzene (NB). The bimetallic 5Fe2.5Cu-Al2O3 catalyst showed a 100% NB (100 ppm) removal within 1 h, which was superior to the NB degradation efficiency over monometallic Fe and Cu catalysts. With combination of the catalytic performance and the characterization results of X-ray photoelectron spectroscopy and H2-temperature-programmed reduction, we proposed that the synergistic effect between Fe and Cu species played a vital role in promoting the reduction of Fe3+ to Fe2+, thus enhancing the generation of hydroxyl radicals ( OH) and the degradation efficiency of NB. To elucidate the degradation pathway, gas chromatography-mass spectrometry and dynamic ultraviolet-visible spectroscopy were used to detect the intermediates during the degradation process. The results indicated that the degradation predominantly occurred via electrophilic addition of aromatic ring by OH, followed by the ring opening reaction and mineralization reaction. Moreover, NB can be efficiently decomposed into less stable aniline, which is apt to degrade. This work has not only made significant progress on the development of high-performance catalysts for the degradation of NB, but also provided a deep understanding of the mechanism for NB degradation.
191 citations
TL;DR: The sorption of phenanthrene and nitrobenzene to micron-, submicron- and nano- sized polystyrene microplastics is investigated to improve the understanding of the fate and risks of microplastic associated with the two typical organic contaminants in the micrometer to nanometer scale.
178 citations
TL;DR: In this paper, an amphiphilic two-dimensional g-C3N4 nanosheets (CNNS) with two hydrophilic/hydrophobic functionalities synthesized by soft-chemical exfoliation and covalent modification with the 4-trifluoromethyl)benzyl (TFMB) group were reported.
Abstract: Phase-boundary catalysis on the liquid–liquid biphasic interface has great potential in various applications due to the advantages of the energy-saving, possibly organic solvent-free process and post-synthesis treatment of products and catalysts. Notwithstanding significant development in visible-light-driven photocatalysis for energy and the environment, the application of graphitic carbon nitride (g-C3N4) in organic synthesis is limited because of its poor dispersibility in organic solvents. Herein, we report amphiphilic two-dimensional g-C3N4 nanosheets (CNNS) with two hydrophilic/hydrophobic functionalities synthesized by soft-chemical exfoliation and covalent modification with the 4-(trifluoromethyl)benzyl (TFMB) group. As a phase-boundary photocatalyst, these amphiphilic CNNS on the oil–water biphasic interface can drive the photocatalytic reduction of nitrobenzene to aniline without any external stirring. Impressively, easy extraction of the synthesized aniline by the water phase favors product separation. Such an amphiphilic CNNS photocatalyst also shows good performance for different organic solvents or even solvent-free systems, multiple reuses, and nitrobenzene compounds substituted with various groups, indicating an innovative application for organic synthesis.
110 citations
TL;DR: In this article, a single-atom photocatalyst (Pt@g-C3N4) was proposed for the hydrogenation of nitrobenzene to aniline under visible light.
Abstract: The hydrogenation of nitrobenzene into aniline is one of industrially important reactions, but still remains great challenge due to the lack of highly active, chemo-selective and eco-friendly catalyst. By using extensive density functional theory (DFT) calculations, herein we predict that single Pt atom decorated g-C3N4 (Pt@g-C3N4) exhibits excellent catalytic activity and selectivity for the conversion of nitrobenzene into aniline under visible light. The overall activation energy barrier for the hydrogenation of nitrobenzene on single atom Pt@g-C3N4 catalyst is even lower than that of the bare Pt(111) surface. The dissociation of N–O bonds on single Pt atom is triggered by single hydrogen atom rather than double hydrogen atoms on the Pt(111) surface. Moreover, the Pt@g-C3N4 catalyst exhibits outstanding chemoselectivity towards the common reducible substituents, such as phenyl,–C=C,–C≡C and–CHO groups during the hydrogenation. In addition, the doped single Pt atom can significantly enhance the photoconversion efficiency by broadening the light absorption of the pristine g-C3N4 to visible light region. Our results highlight an interesting and experimentally synthesized single-atom photocatalyst (Pt@g-C3N4) for efficient hydrogenation of nitrobenzene to aniline under a sustainable and green approach.[Figure not available: see fulltext.].
93 citations
TL;DR: Catalytic studies showed that Ag@TPHH-COF could catalyze the reduction of the various nitroaromatic compounds (NACs) with high efficiency, such as 4-nitrophenol, 2-nitroaniline, nitrobenzene, 4-Nitrotoluene and 1-butyl-4-nitrifying compounds, and has good reusability and high recovery.
Abstract: A covalent organic framework (COF) featuring a unique light porous structure and silver nanoparticles shows high efficiency in the degradation of environmental pollutants. However, the combination of a COF with silver nanoparticles has never been reported until now. Toward this end, 2,4,6-tris-(4-formylphenoxy)-1,3,5-triazine (TPT-CHO) and hydrazine hydrate were selected as the construction units of the COF material (TPHH-COF), which possesses rich nitrogen and oxygen sites. Then a new type of composite catalyst (Ag@TPHH-COF) was successfully obtained by solution infiltration. The obtained materials were also fully characterized by standard methods. The results showed that the silver nanoparticles (with diameters of 5 ± 3 nm) were uniformly dispersed on the surface and in the interlayer gaps of the TPHH-COF substrate. Catalytic studies showed that Ag@TPHH-COF could catalyze the reduction of the various nitroaromatic compounds (NACs) with high efficiency, such as 4-nitrophenol, 2-nitrophenol, 4-nitroaniline, nitrobenzene, 4-nitrotoluene and 1-butyl-4-nitrobenzene. Ag@TPHH-COF could also catalyze the reduction of organic dyes such as Rhodamine B (RhB), Methylene Blue (MB), Methyl Orange (MO) and Congo Red (CR). Moreover, Ag@TPHH-COF has good reusability and high recovery.
75 citations
TL;DR: In this article, the photocatalytic reduction of nitrobenzene into aniline is achieved on non-noble metal thickness-tunable bismuth molybdate nanosheets prepared by the simple hydrothermal reaction.
Abstract: High efficiency and selectivity is significant for photocatalytic organic transformation. In this work, the efficient photocatalytic reduction of nitrobenzene into aniline is achieved on non-noble metal thickness-tunable bismuth molybdate nanosheets prepared by the simple hydrothermal reaction. The photocatalytic activity of Bi2MoO6 strongly depends on the nanosheet thickness. The Bi2MoO6 monolayer displays remarkably enhanced photocatalytic activity for selective reduction of nitrobenzene than bilayer, multilayers and bulk Bi2MoO6 due to the unique properties of 2D materials with the large fraction of surface atoms and the ultrafast charge separation. The obtained conversion rate of 487.5 μmol g−1. h-1 (>95% conversion and >99% selectivity within 60 min reaction) on Bi2MoO6 monolayers is 5 times higher than that of Bi2MoO6 bulk, far exceeding most of common photocatalysts up to date. This work provides a thickness dependent nanosheet concept in the design of newly highly efficient catalysts for the photocatalytic reduction conversion of nitroarenes to anilines.
75 citations
TL;DR: AuNP@PPh2-PIILP is an extremely efficient multiproduct selective catalyst for the sodium borohydride-mediate process as mentioned in this paper, and it is stabilized by phosphine-decorated polymer immobilized ionic liquids.
Abstract: Gold nanoparticles stabilized by phosphine-decorated polymer immobilized ionic liquids (AuNP@PPh2-PIILP) is an extremely efficient multiproduct selective catalyst for the sodium borohydride-mediate...
70 citations
TL;DR: In this paper, pyrite, a ubiquitous sulfide mineral in anaerobic environment, was adopted to enhance the reactivity of ZVI for removal of nitrobenzene.
Abstract: Zero-valent iron (ZVI) is a popular reductant that has been successfully applied for remediation of groundwater contaminated with various pollutants, but it still suffers from surface passivation and pH increase in the reaction media. In this study, pyrite, a ubiquitous sulfide mineral in anaerobic environment, was adopted to enhance the reactivity of ZVI for removal of nitrobenzene. The synergetic effect between pyrite and ZVI was observed for nitrobenzene reduction, and the rate constant kobs at the initial pH (pH0) 6.0 was enhanced by 8.55–23.1 folds due to the presence of pyrite with pyrite/ZVI mass ratio ranging from 1.0 to 6.0. Moreover, nitrobenzene could be removed effectively at pH0 ranging from 5.0 to 10.0 in the presence of pyrite, while negligible removal of nitrobenzene by ZVI (0.5 g/L) alone was observed at pH0 ≥7.0. ZVI sample recovered from the reacted ZVI/pyrite mixture was also more effective for nitrobenzene degradation than pristine ZVI. The mechanism study revealed that pyrite could suppress the pH increase in reaction media, boost the production of reactive Fe2+, and activate the ZVI surface through replacing partially the passive oxide film with iron sulfide (FeS). In particular, the formation of highly reactive FeS@Fe in the reaction system of ZVI/pyrite mixture was proved by XRD, Mossbauer, XANES, XPS and SEM-EDS analyses, which provides a facile way for in-situ sulfidation of ZVI and for enhancing the removal of contaminants with ZVI technology.
66 citations
TL;DR: In this paper, a S-TiO2/SiO2 photocatalyst with visible-light response was synthesized by a simple co-hydrolysis method with thiourea (CH4N2S) as sulfur source and tetraethoxysilane (TEOS) as Si source.
63 citations
TL;DR: In this article, the feasibility of Fe(II)/chlorine system to remove synthetic dyes from water was investigated and it was found that the presence of chlorine in solution containing 25 µM of Fe (II) at pH 5 accelerated the removal of dyes by more than 60% within 30 years of treatment.
53 citations
TL;DR: The fabrication of heterogeneous structure improves the spatial separation and migration of photoinduced electron-hole pairs, thus contributing to the enhancement of photocatalytic properties, and can offer a strategy to develop heterostructure composites for efficient synthesis of organics by photocatalysis under mild conditions.
Abstract: A series of novel CdS/CdIn2S4 composite materials were prepared via a one-pot solvothermal process. The as-obtained photocatalysts were characterized by several techniques and the photocatalytic properties of CdS/CdIn2S4 photocatalysts were studied by photocascade synthesis of Schiff base compounds in a photocatalytic reaction system of aromatic alcohols and nitrobenzene irradiated with visible light. The results reveal that the resulting CdS/CdIn2S4 heterostructure samples show outstanding photocatalytic activities toward the photocascade production of Schiff base compounds in an aromatic alcohols and nitrobenzene reaction system irradiated with visible light. An optimized 50.0% CdS/CdIn2S4 heterostructure sample shows the highest Schiff base yield of 42.0% irradiated with visible light for 4 h, which is approximately 19.1 and 1.54 times higher than those of sole CdS and CdIn2S4 samples, respectively. The fabrication of heterogeneous structure improves the spatial separation and migration of photoinduced electron-hole pairs, thus contributing to the enhancement of photocatalytic properties. We foresee that this finding can offer a strategy to develop heterostructure composites for efficient synthesis of organics by photocatalysis under mild conditions.
TL;DR: The ball-milling-induced inter-particle compaction effect was considered crucial to facilitate the interfacial mass/electron transfer processes during the reduction of nitrobenzene, and the enhanced reactivity synergistically resulted from both chemical and physical aspects.
TL;DR: In this paper, N-doped porous carbons incorporating highlydispersed non-noble metallic cobalt (Co) nanoparticle materials were synthesized by rapid pyrolysis of a zeolitic-type metal-organic framework (ZIF-9) and their structures, morphologies, topologies and relevant physical and chemical properties were fully measured by different characterization technologies.
TL;DR: Magnetic biochar (MBC) was prepared by dispersion of α-Fe2O3 and Fe3O4 particles on high surface area (663 m2/g) Douglas fir biochar.
TL;DR: The rate of reduction of nitrobenzene is found to be higher with thermally exfoliated g-C3N4, and the selectivity of aniline is foundto be higher in the case of chemical exfoliation g- C3N 4.
Abstract: Thermally and chemically exfoliated metal-free semiconducting g-C3N4 are synthesized from bulk g-C3N4. Thorough characterization of the synthesized materials is performed with the help of XRD, FTIR, FE-SEM, PL, surface area analysis and DRS to probe differences in structural, morphological and optical properties between thermally and chemically exfoliated g-C3N4. The synthesized materials are exposed to light for photocatalytic reduction of nitrobenzene. The complete reduction reaction mechanism and product selectivity over the synthesized catalysts are studied in this report. The rate of reduction of nitrobenzene is found to be higher with thermally exfoliated g-C3N4, and the selectivity of aniline is found to be higher in the case of chemical exfoliated g-C3N4. The differences in the reactivity are explained in terms of structure, surface morphologies and band edge positions.
TL;DR: In this paper, a metal organic framework, functionalized with amino groups, was employed as the sorbent for dispersive solid phase extraction to pretreat eight nitrobenzene compounds from environmental water samples.
TL;DR: The degradation of nitrobenzene by synchronistic oxidation and reduction was investigated using an internal circulation microelectrolysis (ICE) reactor with an active volume of 0.018 m3, exhibiting a markedly higher nitrorene degradation efficiency than a conventional fixed bed reactor.
TL;DR: In this article, an environment-friendly and low-cost green synthesis route for preparation of oxygen and nitrogen co-doped porous carbon (ONPC) via acid oxidation and alkali activation methods using coal tar- and residual oil-based as starting materials, and the prepared ONPC was employed as metal-free carbon catalyst for nitroarenes reduction to aminoarenes in the presence of hydrazine hydrate.
TL;DR: Si-doped α-Fe2O3 by controlling the atom ratio of Si/Fe was synthesized for catalytic ozonation of nitrobenzene in aqueous solution as discussed by the authors.
TL;DR: In this paper, the degradation efficiency of nitrobenzene was significantly affected by initial pH, high gravity factor, addition amount of persulfate or ozone, and it achieved the highest value when pH at 10, pH at 40, and initially respective concentrations of extra added persulfates and ozone at 2.5 mmol·L l 1 and 60 mg·L 1.
Abstract: In this study, nitrobenzene was degraded using ozone/persulfate oxidation process in a rotating packed bed with semi-batch operation. NB degradation efficiencies by only using ozone or persulfate in the oxidation system were at 69.44% and 27.14%, respectively, whereas O3/Na2S2O8 system achieved degradation efficiency at 90.59% in 30 min. It was discovered that degradation efficiency of nitrobenzene was significantly affected by initial pH, high gravity factor, addition amount of persulfate or ozone, and it achieved the highest value when pH at 10, high gravity factor at 40, and initially respective concentrations of extra added persulfate and ozone at 2.5 mmol·L − 1 and 60 mg·L − 1. The production of hydroxyl radicals (·OH) and sulfate radicals (SO4·−) was directly identified in electron paramagnetic resonance tests and indirectly through capturing tests, and three ways of oxidation were determined including direct oxidation by O3, indirect oxidation by ·OH and SO4·−, within which ·OH played a significant role in oxidation process. This study also used gas chromatography-mass spectrometry to detect the intermediates in the oxidation process, and two degradation pathways were inferred based on intermediate analysis.
TL;DR: In this article, a bifunctional Ni@C-CeO2 catalyst was proposed for the direct hydrogenation of nitroarenes with H2 to give aromatic azoxy compounds under base-free mild conditions.
TL;DR: Experimental characterizations and theoretical calculations demonstrate that the surface N sites can effectively trap the nitrobenzene and aniline by their phenyl groups with the formation of three C-N bonds that made the catalyst exhibit excellent catalytic activity and chemoselectivity for the reduction of nitro derivatives under facile conditions.
Abstract: Herein, a series of Fe-based catalysts have been designed and prepared by grinding a mixture of MIL-88d and melamine, and then the mixture was followed by pyrolysis. An unusual Fe/Fe3C-activated site is uniformly encapsulated in the N-doped carbon tubes obtained by pyrolysis of the film-like nanocrystals of MIL-88d. Experimental characterizations and theoretical calculations demonstrate that the surface N sites can effectively trap the nitrobenzene and aniline by their phenyl groups with the formation of three C–N bonds that made the catalyst exhibit excellent catalytic activity (turnover frequencies of ≤11268 h–1 calculated on the basis of nitrobenzene) and chemoselectivity for the reduction of nitro derivatives under facile conditions.
TL;DR: The reaction mechanism and reaction path of 4-NP reduction for BiVO4, Bi and Ag were studied through the density functional theory (DFT) theoretical calculation, which suggested that they exhibit synergistic catalytic effect in the reaction process.
TL;DR: Two enantiomorphic MgII -based metal-organic frameworks, {MgL(H2 O)2 }n (1-D and 1-L) (where H2 L=2,2'-bipyridyl-4,4'-dicarboxylic acid) have been synthesized by solvothermal reaction without any chiral auxiliary.
Abstract: Two enantiomorphic MgII -based metal-organic frameworks, {MgL(H2 O)2 }n (1-D and 1-L) (where H2 L=2,2'-bipyridyl-4,4'-dicarboxylic acid) have been synthesized by solvothermal reaction without any chiral auxiliary. The single-crystal X-ray measurement and the structural analysis indicate that both 1-D and 1-L possess 2-fold interpenetrated frameworks with different left- and right-handed helical chains simultaneously, which serve as chiral source, thus transmitting chirality over the whole frameworks. The fluorescence measurements reveal that they exhibit a strong quenching response to nitrobenzene and could be potentially used as a chemical sensor. Owing to the accessible Lewis acidic sites in channels, they display high catalytic efficiency for cycloaddition reaction of CO2 with epoxides and could be reused five times without losing activity.
TL;DR: Fluorescent metal-organic frameworks (MOFs) as mentioned in this paper emitted solid-state blue or cyan fluorescence emissions at 447±7 nm, which mainly arose from NI-bpy-44 and are dependent on the incorporated solvents.
Abstract: Fluorescent Cd metal-organic frameworks (MOFs), [Cd2 (dicarboxylate)2 (NI-bpy-44)2 ] (dicarboxylate=benzene-1,4-dicarboxylate (1,4-bdc, 1), 2-bromobenzene-1,4-dicarboxylate (Br-1,4-bdc, 2), 2-nitrobenzene-1,4-dicarboxylate (NO2 -1,4-bdc, 3), biphenyl-4,4'-dicarboxylate (bpdc, 4); NI-bpy-44=N-(pyridin-4-yl)-4-(pyridin-4-yl)-1,8-naphthalimide)), featuring non- and twofold interpenetrating pcu-type bipillared-layer open structures with sufficient free voids of 58.4, 51.4, 51.5, and 41.4 %, respectively, have been hydro(solvo)thermally synthesized. MOFs 1-4 emitted solid-state blue or cyan fluorescence emissions at 447±7 nm, which mainly arose from NI-bpy-44 and are dependent on the incorporated solvents. After immersing the crystalline samples in different solvents, that is, H2 O and DMSO (1 and 2) as well as nitrobenzene and phenol (1-4), they exhibited a remarkable fluorescence quenching effect, whereas o-xylene and p-xylene (4) caused significant fluorescence enhancement. The sensing ability of MOFs 1-4 toward nitro compounds carried out in the vapor phase showed that nitrobenzene and 2-nitrophenol displayed detectable fluorescence quenching with 1, 2, and 4 whereas 4-nitrotoluene was an effective fluorescence quencher for 1 and 2; this is most likely attributed to their electron-deficient properties and higher vapor pressures. Moreover, MOFs 1-4 are highly reusable for quick capture of volatile iodine, as supported by clear crystal color change and also by immense fluorescence quenching responses owing to the donor-acceptor interaction. Low-pressure CO2 adsorption isotherms indicate that activated materials 1'-4' are inefficient at taking up CO2 .
TL;DR: In this article, a novel porous triazine-based metal-organic framework, ([Cd (Ligand)]∙2DMF) (1) with strong luminescence, has been constructed via multi-carboxyl ligand 5,5′,5''-((1,3,5-triazine-2,4,6-triyl)tris(azanediyl))tris (3-methylbenzoic acid) under solvothermal conditions.
TL;DR: In this paper, a facile visible-light-initiated one-pot strategy for clean and efficient synthesis of nitrone from nitrobenzene and benzyl alcohol is presented.
TL;DR: A core-shell structure electrocatalyst for trace nitrobenzene reduction was prepared with Mn(II)[5,10,15,20-tetra(4-aminophenyl)porphyrin] (MnTAPP) and graphene oxide (GO) as raw materials.
Abstract: A core–shell structure electrocatalyst for trace nitrobenzene reduction was prepared with Mn(II)[5,10,15,20-tetra(4-aminophenyl)porphyrin] (MnTAPP) and graphene oxide (GO) as raw materials. Firstly, MnTAPP and GO were combined together by covalent bonds, and then the supported MnTAPP was coupled together through p-dibromobenzene, a conjugated bridging agent, to obtain a more stable graphene-oxide@polymerized-manganese-porphyrin composite (GMPP@AMP). The structure and morphology of the GMPP@AMP were characterized by FT-IR, Raman spectroscopy, SEM and TEM. The GMPP@AMP modified glassy carbon electrode (GMPP@AMP/GCE) was prepared and the electrochemical activity of GMPP@AMP towards nitrobenzene reduction was evaluated by cyclic voltammetry (CV). The results showed that GMPP@AMP/GCE had a more positive reduction potential than MnTAPP/GCE and GO/GCE, and the reduction current responded more sensitively. Electrocatalytic reduction currents of nitrobenzene were found to be linearly related to concentration over the range 0.04 to 0.24 mM using a differential pulse voltammogram (DPV) method. Nitrobenzene is easily compatible with polymerized MnTAPP which has rich nitrogen-containing functional groups and porous structure, and the highly conductive GO combined with the polymerized MnTAPP having excellent electron transfer ability. This produced a significant synergistic catalytic effect during the electrocatalytic reaction of trace nitrobenzene. The novel composite has good application prospects in electrochemical detection of trace nitrobenzene compounds in the environment.
31 Jan 2019
TL;DR: In this article, a simple and convenient protocol is reported for the conversion of nitrobenzene to aminoarenes by employing CeO2 nanoparticles (n-CeO2) as heterogeneous solid catalysts using hydrazine hydrate as reducing agent under mild reaction conditions.
Abstract: A simple and convenient protocol is reported for the conversion of nitroarenes to aminoarenes by employing CeO2 nanoparticles (n-CeO2) as heterogeneous solid catalysts using hydrazine hydrate as reducing agent under mild reaction conditions. A quantitative conversion of nitrobenzene is achieved using n-CeO2 as solid catalyst with aniline selectivity to 93%. Further, this catalyst is also effectively used to transform wide range of nitroarenes to their respective aniline derivatives in higher conversions and selectivities. The reaction is found to be heterogeneous by leaching experiment and n-CeO2 can be used for three cycles with no drop in its activity. Furthermore, the analyses of the fresh and three times used n-CeO2 samples by powder X-ray diffraction (XRD), UV-Vis diffuse reflectance spectra (DRS), Fourier Transform-Infrared Spectroscopy (FT-IR), scanning electron microscope (SEM) and transmission electron microscope (TEM) indicate that the structural integrity, surface morphology and particle size remain unaltered during the course of the reaction. Furthermore, the valence state of Ce in n-CeO2 is identical in the fresh and three times used samples as evidenced by Fourier Transform Raman spectroscopy. Some of the salient features of this process are operational simplicity, high conversion/selectivity, functional group tolerance, absence of noble metals/additives and reusability of the catalyst.