3964-52-1Relevant articles and documents
Catalytic Activities of Mono- and Bimetallic (Gold/Silver) Nanoshell-Coated Gold Nanocubes toward Catalytic Reduction of Nitroaromatics
Sundarapandi, Manickam,Viswanathan, Perumal,Sivakumar, Shanmugam,Ramaraj, Ramasamy
, p. 13897 - 13904 (2018)
A new class of core-shell metallic nanostructures with tunable near-surface composition and surface morphology with excellent catalytic activity is reported. Very thin shells of metal nanoassemblies such as monolayer (Ag and Au), bilayer of Ag or Au, and AgAu alloy layer with controlled size and morphology were deposited onto a gold nanocube (AuNC) core. UV-vis absorption spectroscopy and high-resolution transmission electron microscopy analyses along with selected-area electron diffraction, energy dispersive X-ray spectroscopy, inductively coupled plasma mass spectrometer, and X-ray diffraction techniques were used to characterize the prepared core-shell nanocubes. High-angle annular dark field scanning transmission electron microscopy-energy dispersive X-ray spectroscopy mapping images were recorded for the bilayer shell and alloy layer shell in the core-shell nanostructures. Reduction of 4-nitroaniline in the presence of sodium borohydride was chosen to validate the catalytic activity of the prepared core-shell metal nanocubes. Interestingly, the AgAu alloy shell layer over the AuNC (AuNC1@Ag0.25Au0.25) showed excellent catalytic activity compared with the pristine AuNC and monolayer and bilayer core-shell nanostructures.
Pd nanoparticles partially embedded in the inner wall of nitrogen-doped carbon hollow spheres as nanoreactors for catalytic reduction of 4-nitrophenol
Bian, Shao-Wei,Liu, Si,Guo, Mei-Xia,Xu, Ling-Li,Chang, Lan
, p. 11913 - 11916 (2015)
Pd@nitrogen-doped carbon nanoreactors (Pd@NC) were synthesized by partially embedding small Pd nanoparticles in the inner wall of the nitrogen-doped carbon shells. Such embedment is critical for improving catalytic activity and stability.
Nitrogen-doped carbon supported iron oxide as efficient catalysts for chemoselective hydrogenation of nitroarenes
Xu, Shaodan,Yu, Deqing,Liao, Shangfu,Ye, Tao,Sheng, Huadong
, p. 96431 - 96435 (2016)
Chemoselective hydrogenation has been widely used in the production of fine chemicals, and developing heterogeneous catalysts with high activity and chemoselectivity is always a challenging topic. Herein, we report a new type of catalysts synthesized from biomass-derived chitosan and non-noble iron, which is denoted as nitrogen-doped carbon supported iron (Fe/N-C). TEM and XRD characterization indicate the presence of iron species. Interestingly, the Fe/N-C catalysts exhibited excellent catalytic performances in the hydrogenation of nitroarenes, and excellent yields of target aniline products could be obtained under industrially viable conditions.
Record-high catalytic hydrogenated activity in nitroarenes reduction derived from in-situ nascent active metals enabled by constructing bimetallic phosphate
Yang, Fu,Wang, Jin,Gao, Shuying,Zhou, Shijian,Kong, Yan
, (2020/03/10)
Herein, we report an excellent in-situ exsolution triggered hydrogenated catalyst F-Ni/Cu-P-RT started from bimetallic phosphate Ni/Cu-P-RT, affording an ultrafast catalytic hydrogenated rate (20 s even 5 s) in nitrophenol reduction. In the first catalytic cycle, we proved the enhanced catalytic reduction activity of bimetallic Ni/Cu-P-RT within 50 s compared to monometallic counterparts. The kinetics results revealed Ni/Cu-P-RT affords the reaction rate K of 2.85/4.23/6.6 min?1 at 20, 30, and 40 °C with the activation energy 32 kJ/mol. Impressively, the involved reaction induction period is visibly observed and interpreted by reconstruction and evolution of active metal during the reaction, but was eliminated through integrating two metal Cu-Ni by regulation of electronic band energy of phosphate from 4.1–3.5 eV. The nascent Cu and Ni nanoparticles as reaction-preferred active species were in-situ exsolved partially after adding NaBH4, triggering the resulted higher active and stable F-Ni/Cu-P-RT(20 s, 14.1 min?1) in later multiple cycles.
Pd-Co catalysts prepared from palladium-doped cobalt titanate precursors for chemoselective hydrogenation of halonitroarenes
Bustamante, Tatiana M.,Dinamarca, Robinson,Torres, Cecilia C.,Pecchi, Gina,Campos, Cristian H.
, (2019/12/24)
Bimetallic Pd-Co catalysts supported on the mixed oxides CoTiO3-CoO-TiO2 (CTO) were synthesized via the thermal reduction of Pd-doped cobalt titanates PdxCo1-xTiO3 and evaluated for the chemoselective hydrogenation of halonitroarenes to haloarene-amines. The nominal Pd mass percentage of the Pd-Co/CTO systems was varied from 0.0 to 0.50. After the thermal reduction of PdxCo1-xTiO3 at 500 °C for 3 h, Pd was completely reduced and Co was partially reduced, producing a mixture of ionic Co, metallic Co, and TiO2-rutile species to give the supported bimetallic catalysts. The metallic cobalt content increased with the Pd content of the precursor. The catalytic activity toward 4-chloronitrobenzene increased with the Pd content; however, >0.1 mass% Pd decreased the chemoselectivity toward 4-chloroaniline due to the formation of the hydrodehalogenation product—aniline. The 0.1Pd-Co/CTO system was used as a model catalyst to produce haloarene-amine building blocks for linezolid, loxapine, lapatinib, and sorafenib with >98% conversion, 96% chemoselectivity, and no hydrohalogenation products. Finally, recycling tests of the 0.1Pd-Co/CTO catalyst showed loss of activity and selectivity during the third cycle due to catalyst deactivation. Regeneration treatments, every two catalytic cycles, allowed six operation cycles without loss of chemoselectivity and only a slight decrease in catalytic activity during the last cycle.
Ultrafine silver nanoparticles supported on a covalent carbazole framework as high-efficiency nanocatalysts for nitrophenol reduction
Gong, Wei,Wu, Qianqian,Jiang, Guoxing,Li, Guangji
supporting information, p. 13449 - 13454 (2019/06/13)
A novel conjugated microporous polymer (CMP) material CZ-TEB was synthesized with a carbazole analogue and 1,3,5-triethynylbenzene. It possessed a high specific surface area, excellent thermal stability and layered-sheet morphology. Furthermore, ultrafine silver nanoparticles were successfully immobilized on CZ-TEB, thus preparing a nanocatalyst Ag0@CZ-TEB. To evaluate its catalytic performance, Ag0@CZ-TEB was exploited in the reduction reaction of nitrophenols, a family of priority pollutants. Ag0@CZ-TEB exhibited high catalytic ability, convenient recovery and excellent reusability. Strikingly, the normalized rate constant (knor) of the reduction reaction of 4-NP to 4-AP is as high as 21.49 mmol-1 s-1. This result shows a significant improvement over all previously reported work. We purposed to use a "capture-release" model to explain the high catalytic ability of Ag0@CZ-TEB. This explanation is supported by further experimental results that agree well with the "capture-release" model.
Fe-Catalyzed Amination of (Hetero)Arenes with a Redox-Active Aminating Reagent under Mild Conditions
Liu, Jianzhong,Wu, Kai,Shen, Tao,Liang, Yujie,Zou, Miancheng,Zhu, Yuchao,Li, Xinwei,Li, Xinyao,Jiao, Ning
supporting information, p. 563 - 567 (2017/01/18)
A novel and efficient Fe-catalyzed direct C?H amination (NH2) of arenes is reported using a new redox-active aminating reagent. The reaction is simple, and can be performed under air, mild, and redox-neutral conditions. This protocol has a broad substrate scope and could be used in the late-stage modification of bioactive compounds. Mechanistic studies demonstrate that a radical pathway could be involved in this transformation.
Zwitterionic Surfactant stabilized palladium nanoparticles as catalysts in aromatic nitro compound reductions
Souza, Franciane D.,Fiedler, Haidi,Nome, Faruk
, p. 372 - 381 (2016/03/19)
Palladium nanoparticles (NPs) stabilized by ImS3-14, a zwitterionic surfactant structurally related to ionic liquids, are revealed here to be good catalysts for the reduction of a large number of substituted aromatic nitro compounds. Our mass spectrometry results are consistent with the formation of amino products in a direct route, where the aromatic nitro compounds are initially reduced to nitroso compounds, which are then reduced to the hydroxylamine derivatives and finally to the anilines. Activation parameters showed that for most Pd catalysts reported in the literature, the mechanism seems to be similar, with lower enthalpy of activation (ΔH?) being compensated by more negative entropy of activation (ΔS?). As a result, the reaction is thermally compensated and the rate constants for most reactions rather similar. Furthermore, Pd NPs stabilized by ImS3-14 showed efficient catalytic activities for the reduction of aromatic nitro compounds, with high conversion and good selectivity even using very low loadings of metal.
Activity and Selectivity in Nitroarene Hydrogenation over Au Nanoparticles on the Edge/Corner of Anatase
Wang, Liang,Zhang, Jian,Wang, Hong,Shao, Yi,Liu, Xiaohui,Wang, Yan-Qin,Lewis, James P.,Xiao, Feng-Shou
, p. 4110 - 4116 (2016/07/12)
Highly selective hydrogenation of molecules containing more than one reducible group is always challenging. Here we report an efficient strategy for rational preparation of highly selective gold-based catalysts in the hydrogenation of substituted nitroarenes by positioning gold nanoparticles on the edge/corner sites of anatase. Mechanistic studies reveal that the catalyst with gold nanoparticles on the edge/corner sites of anatase could form unique sites for selective adsorption and activation of nitro groups, thus leading to high activity and selectivity. This strategy for preparation of supported gold catalysts opens a new door for the design of highly efficient heterogeneous catalysts in the future.
Monodispersed Ag nanoparticles as catalyst: Preparation based on crystalline supramolecular hybrid of decamethylcucurbit[5]uril and silver ions
Li, Hong-Fang,Lue, Jian,Lin, Jing-Xiang,Cao, Rong
, p. 5692 - 5697 (2014/06/23)
Monodispersed silver nanoparticles (Ag0 NPs) have been first prepared on the basis of a postsynthesis via mild reduction from a new crystalline supramolecular hybrid solid assembled from Ag+ ions and decamethylcucurbit[5]uril (Me10CB[5]). Uniform growth of nearly spherical Ag0 NPs with an average size of ca. 4.4 nm was observed on the organic Me10CB[5] support to form Ag@Me10CB[5] composite material. The as-synthesized composite material was characterized by a range of physical measurements (PXRD, TGA, XPS, ICP, TEM, etc.) and was further exploited as a heterogeneous catalyst for the reduction of various nitrophenols in the presence of NaBH4. The kinetics of the reduction process was monitored under various experimental conditions. The Ag@Me10CB[5] composite material showed excellent catalytic performance over the reduction reactions and remained active after several consecutive cycles.
