Academic literature on the topic 'Chloronitrobenzene hydrogenation'
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Journal articles on the topic "Chloronitrobenzene hydrogenation"
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Wu, Jie, Guang Yin Fan, and Wen Jun Huang. "Selective Hydrogenation of p-Chloronitrobenzene Catalyzed by FexOY@C Supported Pt-Catalyst." Advanced Materials Research 960-961 (June 2014): 221–24. http://dx.doi.org/10.4028/www.scientific.net/amr.960-961.221.
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FexOy@C nanocomposites were synthesized and used as carriers for depositing Pt nanoparticles. Catalytic properties of the nanocomposites were investigated for the hydrogenation of p-chloronitrobenzene at room temperature and balloon hydrogen pressure. The catalyst Pt/FexOy@C was extremely active for the hydrogenation of p-chloronitrobenzene. Completely conversion of p-chloronitrobenzene was achieved with a selectivity of 99.7 % in ethanol-water mixture in a reaction time of 40 min. Moreover, it can be reused four times without loss of any activity.
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Chen, Hu, Daiping He, Qingqing He, Ping Jiang, Gongbing Zhou, and Wensheng Fu. "Selective hydrogenation of p-chloronitrobenzene over an Fe promoted Pt/AC catalyst." RSC Advances 7, no. 46 (2017): 29143–48. http://dx.doi.org/10.1039/c7ra04700b.
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Wang, Ping, Shiyi Wang, Ronghe Lin, Xiaoling Mou, and Yunjie Ding. "Pre-Coking Strategy Strengthening Stability Performance of Supported Nickel Catalysts in Chloronitrobenzene Hydrogenation." Catalysts 11, no. 10 (September 26, 2021): 1156. http://dx.doi.org/10.3390/catal11101156.
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Supported nickel catalysts represent a class of important catalytic materials in selective hydrogenations, but applications are frequently limited by metal agglomeration or active-site blocking induced by the presence of hydrogen halides. Herein, we report a novel pre-coking strategy, exposing the nickel nanoparticles under methane dry reforming conditions to manipulate performance in the continuous-flow hydrogenation of 1,2-dichloro-4-nitrobenzene. Compared with the pristine nickel catalyst, the nanotube-like coke-modified nickel catalyst showed weakened hydrogenating ability, but much improved stability and slightly better selectivity to the target product, 3,4-dichloroaniline. Characterization results revealed that the strengthened stability performance can be mainly linked to the reduced propensity to retain chlorine species, which seems to block the access of the substrate molecules to the active sites, and thus is a major cause of catalyst deactivation on the pristine nickel catalyst. Coke deposition can occur on the pre-coked nickel catalyst but not on the pristine analog; however, the impact on the stability performance is much milder compared with that on chlorine uptake. In addition, the presence of coke is also beneficial in restraining the growth of the nickel nanoparticles. Generally, the developed method might provide an alternative perspective on the design of novel transition-metal-based catalytic materials for other hydrogenation applications under harsh conditions.
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Zhu, Donghong, Xin Weng, Yuqiong Tang, Jingya Sun, Shourong Zheng, and Zhaoyi Xu. "Pt/Al2O3 coated with N-doped carbon as a highly selective and stable catalyst for catalytic hydrogenation of p-chloronitrobenzene to p-chloroaniline." RSC Advances 10, no. 24 (2020): 14208–16. http://dx.doi.org/10.1039/d0ra01578d.
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Liu, Hongmei, Kai Tao, Chunrong Xiong, and Shenghu Zhou. "Controlled synthesis of Pd–NiO@SiO2 mesoporous core–shell nanoparticles and their enhanced catalytic performance for p-chloronitrobenzene hydrogenation with H2." Catalysis Science & Technology 5, no. 1 (2015): 405–14. http://dx.doi.org/10.1039/c4cy00996g.
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Pietrowski, Mariusz, Michał Zieliński, and Maria Wojciechowska. "Nanocolloidal Ru/MgF2 Catalyst for Hydrogenation of Chloronitrobenzene and Toluene." Polish Journal of Chemical Technology 16, no. 2 (June 26, 2014): 63–68. http://dx.doi.org/10.2478/pjct-2014-0031.
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Abstract The use of magnesium fluoride support for ruthenium active phase allowed obtaining new catalysts of high activities in the hydrogenation of toluene and ortho-chloronitrobenzene. Ruthenium colloid catalysts (1 wt.% of Ru) were prepared by impregnation of the support with the earlier produced polyvinylpyrrolidone (PVP)-stabilized ruthenium colloids. The performances of the colloidal catalysts and those obtained by traditional impregnation were tested in the reactions of toluene hydrogenation to methylcyclohexane and selective hydrogenation of ortho-chloronitrobenzene (o-CNB) to ortho-chloroaniline (o-CAN). It was shown that the use of chemical reduction method allows obtaining highly monodisperse ruthenium nanoparticles of 1.6–2.6 nm in size. After reduction in hydrogen at 400oC, the colloidal ruthenium nanoparticles were found to strongly interact with MgF2 surface (SMSI), which decreased the catalyst ability to hydrogen chemisorption, but despite this, the colloid catalysts showed higher activity in o-CNB hydrogenation and higher selectivity to o-CAN than the traditional ones. It is supposed that their higher activity can be a result of high dispersion of Ru in colloid catalysts and the higher selectivity can be a consequence of the lower availability of hydrogen on the surface.
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Fan, Guang Yin, and Chun Zhang. "Effective Hydrogenation of p-Chloronitrobenzene over Iridium Nanoparticles Entrapped in Aluminum Oxy-Hydroxide under Mild Conditions." Advanced Materials Research 881-883 (January 2014): 267–70. http://dx.doi.org/10.4028/www.scientific.net/amr.881-883.267.
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The Ir/AlO(OH) catalyst was prepared by sol-gel method and used for selective hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroniamine (p-CAN). The mechanism of p-CNB hydrogenation over the catalyst was discussed. The hydrogen bond between the surface hydroxyl groups of the catalyst and the nitrogen present in p-CNB facilitated the hydrogenation of nitro group. On the other hand, the formation of hydrogen bond between the hydrogenation product and water promotes the rapid desorption of the hydrogenation product on the surface of the catalyst. Thus the activity and selectivity were greatly promoted.
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Chen, Yin-Zu, and Yih-Chung Chen. "Hydrogenation of para-chloronitrobenzene over nickel borides." Applied Catalysis A: General 115, no. 1 (August 1994): 45–57. http://dx.doi.org/10.1016/0926-860x(94)80377-3.
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Wang, Xiao Zhen, Yi Feng Zhu, and Xiao Nian Li. "Kinetics of ο-Chloronitrobenzene Hydrogenation on Palladium/Carbon Catalyst." Advanced Materials Research 239-242 (May 2011): 161–67. http://dx.doi.org/10.4028/www.scientific.net/amr.239-242.161.
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A 2 wt % Pd/C catalyst has been prepared by chemical impregnation and used to catalyze the hydrogenation of o-chloronitrobenzene (o-CNB) to o-chloroaniline (o-CAN) in solvent-free conditions. The effects of reaction temperature, H2 pressure, and stirring intensity on the hydrogenation kinetics have been investigated. The hydrogenation reaction showed very high selectivity with dehalogenation side products as low as 0.3% of total yield. The favorable reaction conditions were found to be temperature T = 383 K, stirring speed = 900 rpm, and feeding ratio CNB/catalyst = 200/1 (m/m). The recycled Pd/C still retained more than 98% of its original selectivity after 12 repeat used, indicating the catalyst had strong potentials for commercial application at industrial scale.
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Dobrosielska, Marta, Michał Zieliński, Miłosz Frydrych, Mariusz Pietrowski, Piotr Marciniak, Agnieszka Martyła, Bogna Sztorch, and Robert E. Przekop. "Sol–Gel Approach for Design of Pt/Al2O3-TiO2 System—Synthesis and Catalytic Tests." Ceramics 4, no. 4 (December 8, 2021): 667–80. http://dx.doi.org/10.3390/ceramics4040047.
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Al2O3-TiO2 systems with Ti:Al 0.1, 0.5 and 1.0 molar ratio obtained by the sol–gel method have been used as a platinum support. As a precursor of alumina gel, aluminum isopropoxide has been chosen. Titanium tert-butoxylate was applied to obtain titania gel and hexachloroplatinic acid was applied as a source of platinum. The systems have been characterized by the following methods: thermogravimetric analysis (TGA), Fourier transformation infrared spectroscopy (FTIR), X-ray powder diffraction (XRPD), low-temperature nitrogen adsorption–desorption isotherms (BET, BJH), temperature-programmed reduction with hydrogen (TPR-H2) and hydrogen chemisorption. Reactions of toluene to methylcyclohexane and selective o-chloronitrobenzene (o-CNB) to o-chloroaniline (o-CAN) hydrogenation were used as the tests of systems’ catalytic activity. The application of Al2O3-TiO2 as a support has enabled the obtaining of platinum catalysts showing high activities for hydrogenation of toluene and selective hydrogenation of o-chloronitrobenzene to o-chloroaniline in the liquid phase. The highest activity in both reactions has been found for Pt/Al2O3-0.5TiO2 catalyst and the highest selectivity for Pt/Al2O3-. The activity of Pt/Al2O3-TiO2 catalysts was higher than that of alumina-supported ones.
Dissertations / Theses on the topic "Chloronitrobenzene hydrogenation"
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VANNI, MATTEO. "Functionalization of Black Phosphorus with Inorganic Reagents." Doctoral thesis, Università di Siena, 2021. http://hdl.handle.net/11365/1127348.
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Since its first reported exfoliation in 2014, the interest in black phosphorus has grown dramatically. The direct band gap, the high carrier mobility and the large specific surface area of BP open up great opportunities in different topical sectors of physics and chemistry including catalysis. As each phosphorus atom in BP has an sp3 hybridization and is bearing a lone-pair, an effective approach to surface modification could encompass the coordination of transition metal fragments. In this thesis, the functionalization of exfoliated black phosphorus (2D BP) with different palladium precursors is presented. In particular, a new nanohybrid was obtained growing Pd NPs in situ on 2D BP. The new material, named Pd/BP, was characterized by means of different spectroscopic techniques and electron microscopy measurements. The existence of Pd‒P bonds of 2.26(3) Å between peripheral Pd atoms of the nanoparticles and BP flakes was revealed via EXAFS measurements, highlighting the ability of 2D BP to act as an effective ligand toward the surface of metal NPs. The nanohybrid Pd/BP was used successfully as heterogeneous catalyst in the liquid phase hydrogenation of chloronitrobenzene to chloroaniline, resulting extremely selective in the process. Remarkably, comparative studies carried out with Pd NPs supported on carbon as reference material, revealed that the use of BP as support is crucial to reach higher selectivity.
Following a distinct approach, the functionalization of 2D BP was accomplished by addition of the organometallic precursor [Pd(C3H5)Cl]2 to 2D BP. In-depth solid state characterization carried out by means of powder XRD and solid state 31P CP-MAS NMR allowed to unravel the nature of the new material. HAADF-STEM microscopy performed at atomic level was exploited to probe the morphology of the flakes, revealing the existence of a uniform distribution of the metal within 2D BP, with no formation of metal aggregates, such as Pd NPs. EXAFS measurements, together with DFT simulations, revealed the existence of unprecedented interlayer Pd‒Pd dimers, bridging two BP layers. Consistently with morphological and structural analysis, testing the material (named Pd2/BP) in the benchmark hydrogenation of C=C and C≡C bonds, the metal sites resulted inaccessible to organic substrates. Conversely, preliminary studies on the application of Pd2/BP in the hydrogen evolution reaction (HER) from acidic medium, pointed out a strong enhancement in electrocatalytic activity compared to pristine 2D BP.
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Chan, Chun Wong Aaron. "Ultraselective nanocatalysts in fine chemical and pharmaceutical synthesis." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:866296af-5296-4d2e-8e52-6499dacaef0f.
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Surface catalysed reactions play an important role in chemical productions. Developments of catalyst requiring high activity whilst improving on product selectivity can potentially have a profound effect in the chemical industry. Traditional catalyst modifications were focused on tuning the size, shape and foreign metal doping to form well defined metal nanoparticles of unique functionalities. Here, we show new approach to engineering of metal nanocatalysts via a subsurface approach can modify the chemisorption strength of adsorbates on the surface. Carbon modified nanoparticles were synthesised using glucose to stabilise Pd nanoparticles at a molecular level. Upon heat treatment, the carbonised glucose encapsulated the Pd nanoparticles with carbon atoms take residence in the octahedral holes (15 at.%). These materials were tested in liquid phase stereoselective hydrogenations of 3-hexyn-1-ol and 4-octyne. The former has importance in the fragrance industry towards the production of leaf fragrance alcohol. It was shown for the first time that the geometrically and electronically modified Pd with interstitial carbon atoms reduced the adsorption energy of alkenes, ultimately leading to higher reaction selectivity. Boron modified Pd nanoparticles was synthesised using BH3.THF in the liquid phase. The material possess high B interstitial saturation (20 at.%), which can be synthesised for the first time below 100°C. These materials were tested in the liquid phase selective hydrogenation of various alkynes and 2-chloronitrobenzene, of which the latter has importance in the pesticides industry. Kinetic modelling on the hydrogenation of 4-octyne suggests these subsurface occupied B does play a pivotal role on increasing the reaction selectivity, as removal of these species lead to decreased selectivity. Au nanoparticles were synthesised and characterised using H13COOH NMR. The new liquid NMR characterisation method is successfully applied to examine the chemisorption strength of metal nanoparticles. An attempt to synthesise PVP capped B modified Pd nanoparticles with the above NMR characterisation was investigated. It is believed the examples of subsurface atom modifications as shown here may offer future catalyst developments in this area.
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Chuang, Chia-Nung, and 莊家穠. "Hydrogenation of p-chloronitrobenzene over gold catalysts." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/69694946246919685086.
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碩士國立中央大學
化學工程與材料工程研究所
100
Nanosized gold catalyst has been reported to be a good catalyst for the liquid phase hydrogenation reactions due to their excellent activity and selectivity. In this study, various additives (FeOx, AlOx, CeO2, MgO, MnOx, ZrO) were added into Au/TiO2 catalyst.. The modified-TiO2 support was prepared by incipient-wetness impregnation0. Gold catalysts were prepared by deposition-precipitation method with 4wt. % Au loading. The activity of the modified catalyst was tested for the hydrogenation of p-chloronitrobenzene. These catalysts were characterized by inductively-coupled-plasma-mass spectrometry, X–ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and temperature programmed reduction. The catalytic properties of gold based catalysts were studied on hydrogenation of p–chloronitrobenzene(p-CNB). The conditions for hydrogenation reaction were 1.2 MPa H2 pressure, 353 K reaction temperature and 500 rpm stirring speed. Methanol was used as the solvent, the concentration of p-CNB was 0.2 M (2.54g p–CNB in 80 ml methanol) and the amount of gold based catalyst was 0.5g. For modified gold catalysts, Fe-doped ones were better than the other catalysts, and it had the highest activity and selectivity. A series of Au catalysts supported on FeOx-TiO2 with various Fe contents were prepared. The iron oxide in Au/FeOx-TiO2 played the role of a textural promoter, prevents from sintering of gold particles. The results showed that the additive of Fe could prevent Au0 from being oxidized, increased the active sites and enhanced catalytic activity. Au/ FeOx-TiO2 with Fe/Ti atomic ratio of 4/6 exhibited the highest activity among the series of Au/ FeOx-TiO2. It could be concluded that adding suitable iron amount showed the best performance, and could promote the activity of Au catalyst effectively.
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Su, Jenn-Fang, and 蘇鎮芳. "Hydrogenation of p-Chloronitrobenzene on modified-NiB Catalysts." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/19803594601472719847.
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碩士國立中央大學
化學工程與材料工程研究所
98
NiB alloy catalyst has been reported to be a good catalyst for the hydrogenation of p-chloronitrobenzene to p-chloroaniline. The objective of this study was to investigate the effects of Mo and Pd contents on the catalytic properties of NiB in the hydrogenation of p-chloronitrobenzene. A series of NiB catalysts with various modifiers (Mo, and Pd) were prepared by chemical reduction method using NaBH4 as the reducing agent at 298 K. The catalysts were characterized by inductively coupled plasma-mass spectrometry, X–ray diffraction, transmission electron microscopy, high resolution transmission electron microscopy, energy dispersive spectrometer, and X-ray photoelectron spectroscopy. The catalytic properties of these catalysts for p–chloronitrobenzene (p-CNB) hydrogenation were studied. Adding proper content of modifiers improved the activity, selectivity and thermal stability of NiB. Both of the modified catalysts Mo-NiB and Pd-NiB processed amorphous structure. The Pd and Mo acted as the spacer to prevent the NiB particles from aggregation, so the particle sizes of the modified catalysts were less than that of the unmodified NiB catalysts. Furthermore, the Magnetization of ultrafine particles remarkably increase with doping Pd into NiB. XPS results showed that molybdenum modifier existed both in elemental and oxidized states. Different modifiers had various effects on the surface composition of NiB catalyst. The elemental state of modifier( Mo and Pd) formed nano-alloy with Ni and affected their electron densities which influenced the products distributions (the relative contents of p–chloronitrobenzene, aniline, and nitrobenzene) in the p-CNB hydrogenation. The life time tests NiB and Mo-NiB were also studied. The results showed that Mo additive could extend the life of NiB. After the hydrogenation reaction, the NiB catalyst sintered to numerous large grains. However, Mo-NiB retained the original black nano-clusters and the catalytic activities were maintained at high level after 3 batch runs. These effects were responsible for the different behaviors of Mo-, and Pd-modified NiB catalysts in the p-CNB hydrogenation.
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Jong, Chen Yih, and 陳義忠. "Selective Hydrogenation of p-Chloronitrobenzene over Nickel Borides." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/24328218687836218160.
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Cheng, Chia-Hui, and 鄭嘉蕙. "Hydrogenation of p-chloronitrobenzene on Nanosized modifiedNiMoB catalyst." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/35856089229107735166.
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碩士國立中央大學
化學工程與材料工程研究所
99
Amorphous NiB alloy catalysts are beneficial for the hydrogenation of p-chloronitrobenzene. They possess better catalytic activity and selectivity in the hydrogenation reaction. In this study, we used sodium borohydride to reduce the precursor salts of nickel acetate, ammonium heptamolybdate tetrahydrate and additives (Pd, La, Fe and Co), and prepared a series of modified NiMoB catalyst by chemical reduction method. The molar ratio of Ni/Mo/B/additive was 1: 0.4: 3: 0.1, and an overdose of B was used to completely reduce the precursor salts. Ni catalysts were prepared in 50 vol.% methanolic solution at 298 K under N2 curtain gas with vigorous stirring of 500 rpm. In order to prevent the catalysts from oxidation and deactivation during the preparation, N2 curtain gas was used. The high activity of fresh catalysts was tested for the hydrogenation of p-CNB. The catalysts were characterized by inductively coupled plasma-mass spectrometry (ICP-MS), X–ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), energy dispersive spectrometer (EDS), and X-ray photoelectron spectroscopy (XPS). The activity and selectivity of catalysts were tested for the liquid-phase htdrogenation reaction of p-CNB at 1.2 MPa pressure and two different temperatures, 353 K and 333 K, and under vigorous stirring of 500 rpm in the batch reactor (Parr Reactor Model 4842). The reaction medium was 80 ml methanol. During the run, the samples were withdrawn periodically (10 min) and analyzed by a gas chromatography. The results revealed that adding the additives into the catalysts would enhance the dispersing effect of active sites, activity and selectivity. The selectivity of main product, p-chloroaniline (p-CAN) was more than 90%. For modified NiMoB catalysts, La-doped one was better than the other catalysts, and more obvious electron transfer contributed to the best activity and selectivity. In order to study the influence of La/Ni molar ratio on the catalytic activity of La-doped NiMoB catalysts, the molar ratio of La/Ni was modified and found that the La(0.2)-NiMoB catalyst had excellent hydrogenation activity. It achieved 100% conversion within 60 min at 333 K with selectivity of 97.5%.
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Lin, Ming-Hung, and 林明宏. "The applications of modified NiB catalysts on the hydrogenation of p-chloronitrobenzene." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/58798606194631638873.
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碩士國立中央大學
化學工程與材料工程研究所
96
Amorphous NiB alloy catalysts are beneficial for the hydrogenation of p-chloronitrobenzene (p-CNB). They possess better catalytic activity and selectivity in the hydrogenation reaction. In this study, we used sodium borohydride to reduce the precursor salts of nickel acetate, cobalt acetate and additives (Mo, La, Fe and W), and prepared a series of modified Ni-B and NiCoB catalysts by chemical reduction method. The molar ratio of Ni/Co/B and Ni/additive was relatively 1:0.1:3 and 1:0.1, respectively, and an overdose of B was used to completely reduce the precursor salts. Ni catalysts were prepared in 50 vol.% methanolic solution at 298 K under N2 curtain gas with vigorous stirring of 500 rpm. In order to prevent the catalysts from oxidation and deactivation during the preparation, N2 curtain gas was used. The high activity of fresh catalysts was tested for the hydrogenation of p-CNB. In order to analyze the physical, chemical and surface properties, the as-prepared catalysts were characterized by nitrogen sorption (BET), X–ray diffraction (XRD), transmission electron microscopy (TEM) and X–ray photoelectron spectroscopy (XPS). The activity and selectivity of catalysts were tested for the liquid-phase hydrogenation reaction of p-CNB at 353 K and 1.2MPa H2 pressure under vigorous stirring of 500 rpm in a batch reactor (Parr Reactor Model 4842). The reaction medium was 80 ml methanol. During the run, the samples were withdrawn periodically (10 min) and analyzed by a gas chromatograph. The results revealed that adding the additives into the catalysts would enhance the thermal stability, dispersing effect of active sites, activity and selectivity. The selectivity of main product, p-chloroaniline (p-CAN) was more than 90%. The results of the reaction showed that the performance of the modified NiFeB (1:0.1) was the best one between a series of Fe-doped NiB catalysts and the selectivity also increased significantly. For modified NiCoB catalysts, Mo- and W-doped ones were better than the other catalysts, and more obvious electron transfer contributed to the best activity and selectivity. In order to study the influence of Mo/Ni molar ratio on the catalytic activity of Mo-doped NiCoB catalysts, the molar ratio of Mo/Ni was modified and found that the Mo-NiCoB (0.6:1:0.1) catalyst had excellent hydrogenation activity. It achieved 100% conversion within 10 min with a selectivity of 98%. In order to discuss the characterization of modified catalysts, the XRD patterns confirmed the formation of alloy. All the metals would form alloy and hence the major focus was on the phenomenon of electron transfer. Furthermore, the relationship between the particle size and additives was correlated. The particle size would decrease and the surface area would increase with the introduction of the additives. Therefore, the catalysts were in nano-scale range as confirmed from the TEM images and BET measurement.
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Chen, Yi-Ching, and 陳奕靜. "Hydrogenation of p-Chloronitrobenzene by Ni-B Nanocatalysts in the CO2-Expanded Methanol." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/49556862115619167918.
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Shen, Jia-Huei, and 沈佳慧. "The Preparation and Application of Nickel Nanoalloy Catalysts on the Hydrogenation of p-Chloronitrobenzene." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/61229960067597266817.
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碩士國立中央大學
化學工程與材料工程研究所
95
Aromatic halo-amines are used extensively in industrial applications for the production of fine chemicals, i.e., dyes, herbicides, pesticides, etc. The main route for their production is the selective hydrogenation of the corresponding nitrocompounds over heterogeneous metal catalysts. Considering p-chloronitrobenzene as an example, its N=O group may be hydrogenated or its -Cl may be dehalogenated. Besides the desired product p-chloroaniline, many byproducts such as aniline, nitrobenzene, p-chlorophenylhydroxylamine, p-chloronitrosobenzene, azo- and azoxy-dichlorobenzenes, and chlorobenzene were formed at the same time. The nanomaterials, combining the features of amorphous and nanometer powers, have more surface atoms and a higher concentration of coordinately highly unsaturated sites. Nanometer amorphous alloy powders have attracted extensive attention due to their unique isotropic structural and chemical properties. A series of nickel catalysts were prepared by chemical reduction method. Nickel acetate and sodium hypophosphite or cobalt acetate were mixing in methan, the solution of sodium borohydride in excess amount was then added dropwise into the mixture to ensure full reduction of cations. The as-prepared catalysts were characterized with X-ray diffraction, nitrogen sorption, transmission electron microscopy, and X-ray photoelectron spectroscopy. The initial molar ratios of starting materials affected the concentration of boron bounded to the nickel metals, resulting in the change of surface area, electron structures of the metals and catalytic activities of the catalysts. The XPS results revealed that boron combined with nickel metal in the NiPB powder donates electrons to nickel metal and that phosphorus withdraws electrons from nickel metal. Small amounts of phosphorus in the NiB catalyst can increase the surface area and turnover frequency. Both are beneficial for promoting the reaction. The addition of cobalt into NiB catalyst could reduce the particle of nickel catalyst, improve the particle dispersion, and suppress the growth of crystalline structure of NiB and help the NiB catalyst to maintain its amorphous state. Based on the electron transference between elemental nickel and boron, NiCoB(1:0.1) had the most d-band electrons and the highest electron density, therefore it also has the highest activities of hydrogenation of nitro-group and dehalogenation reactions. Although it had the highest activity of hydrogenation of p-CNB, it lost the selectivity of p-CAN at the same time. The water-soluble polymer of polyvinylpyrolidone was polymerized by vinylpyrolidone, there are –N and –O atom on the molecular chain. Because of the lone pair electrons of functional groups, the multi-coordination produces a considerable strength of chemisorption of polymer on the nano-particle. The polymer adsorbed on the nano-particles might prevent the aggregation of nano-particles by steric stabilization. The PVP polymers effectively had significant effect on the thermal stability. It is demonstrated that adding high pressure carbon dioxide into methanol really can expand the volume of liquid thus the solubility of hydrogen in the solvent will be increased and the resistance of gas-liquid mass transfer will be reduce. Although the pressure is increased up to 3.54 MPa and the concentration of p-CNB is increased to 1.5 M, the hydrogenation of p-CNB is influenced by the effect of gas-liquid mass transfer, but it is mainly controlled by the resistance of the reaction. So even the resistance of gas-liquid mass transfer is reduced, it is unable to cause too great influence on the hydrogenation of p-CNB.
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Chen, Liang-Fu, and 陳亮夫. "Effect of Additives on Ni-B Colloid Catalysts for the Hydrogenation of p-Chloronitrobenzene." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/67440363797111653070.
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碩士國立中央大學
化學工程與材料工程研究所
94
Ni-B amorphous catalysts proved to be a better catalyst on both activity and selectivity for hydrogenation of p-chloronitrobenzene (p-CNB) from previous studies. However, the catalytic activity of Ni-B catalyst did not compete with that of noble metals viz., Pd and Pt. In order to enhance the catalytic activity of Ni-B for the hydrogenation, six additives were introduced into Ni-B amorphous catalyst, including metal salts of Cr, Ce, Th, W, Ru and Mo. A series of modified Ni-B amorphous nanocatalysts were prepared by chemical reduction of mixed salts of the metal additive and nickel acetate tetrahydrate with sodium borohydride in water/methanol solution. The characterization results revealed that at a specific weight ratio of metal dopants, some particles of modified Ni-B catalysts became smaller and have better thermal resistance, and protecting the special amorphous structure even at high temperature. During hydrogenation of p-CNB, some modified Ni-B catalysts have showed lower catalytic activity than unmodified one. However, the catalytic activity of these promoted catalysts are better than Raney nickel used in industries, with high selectivity to the main product of p-CAN (p-chloroaniline). Among these promoted catalysts, Mo-Ni-B showed the best activity and reached almost 100% conversions even at lower reaction temperature of 323K. According to kinetic studies and results of various characterization methods, such as powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and N2 sorption, the correlation of the catalytic performance to both the structural and the electronic characteristics have been arrived and discussed briefly.
Book chapters on the topic "Chloronitrobenzene hydrogenation"
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Smith, Gerard V., Ruozhi Song, Daniel Ostgard, and Russell E. Malz. "Hydrogenation and Dehydrohalogenation of p-Chloronitrobenzene: Effect of Pd Metal Particle Size on Activity and Selectivity." In Catalysis of Organic Reactions, 469–74. Routledge, 2017. http://dx.doi.org/10.1201/9781315138855-47.
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Pietrowski, Mariusz, and Maria Wojciechowska. "The influence of preparation procedure on structural and surface properties of magnesium fluoride support and on the activity of ruthenium catalysts for selective hydrogenation of chloronitrobenzene." In Scientific Bases for the Preparation of Heterogeneous Catalysts - Proceedings of the 10th International Symposium, Louvain-la-Neuve, Belgium, July 11-15, 2010, 505–8. Elsevier, 2010. http://dx.doi.org/10.1016/s0167-2991(10)75095-3.
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