原位液相催化加氢法合成N-乙基苯胺和N，N-二乙基苯胺

以硝基苯为原料,Pt/γ-Al2O3为催化剂,乙醇水溶液为溶剂和氢供体,采用原位液相加氢一步法合成了N-乙基苯胺和N,N-二乙基苯胺.采用低温N2吸附-脱附、电感耦合等离子体发射光谱、X射线衍射、程序升温化学吸附和透射电子显微镜等对Pt/γ-Al2O3催化剂进行了表征,并考察了所制备催化剂的原位液相加氢性能.结果表明,在温度为503K、压力为5.0MPa、空速为3.2h-1、溶剂水含量为30%以及硝基苯浓度为8%的反应条件下,在Pt/γ-Al2O3催化剂上原位液相加氢合成N-乙基苯胺及N,N-二乙基苯胺有较好的结果,硝基苯转化率达到100%,N-乙基苯胺和N,N-二乙基苯胺的总收率达到99.5%.讨论了硝基苯原位液相加氢合成N-乙基苯胺和N,N-二乙基苯胺的反应机理.     

负载铱催化剂选择性催化间二硝基苯制间硝基苯胺

用浸渍法制备的负载铱催化剂催化间二硝基苯部分加氢制间硝基苯胺,考察了温度对反应的影响和催化剂循环实验,结果表明,催化剂活性在90℃最佳;间硝基苯胺选择性随温度升高而增加.以甲醇作溶剂,在n(substrate) /n(Ir) =5000, 90℃, 0.8 MPa条件下,反应1 h,间二硝基苯转化率100%,间硝基苯胺选择性96.3%,全部加氢产物间苯二胺很少生成.催化剂经3次循环,活性下降不明显,在第6次循环时延长反应时间至2.5 h,间二硝基苯转化率和间硝基苯胺选择性均能达到100%.催化机理有待进一步研究.     

NiO/SiO2气凝胶催化剂性能研究 Ⅱ. 顺酐合成丁二酸酐和γ-丁内酯的工艺条件

研究了溶胶-凝胶法制备的NiO-SiO2催化剂上温度,压力,反应时间,催化剂用量等工艺条件对顺酐液相选择加氢性能的影响.结果表明镍含量为30%的NiO/SiO2气凝胶催化剂在适当的反应条件下顺酐液相加氢可高选择性地获得丁二酸酐和γ-丁内酯.当反应温度453K,氢压5.0MPa,反应时间8h,顺酐转化率100%,γ-丁内酯的选择性78.57%;生成丁二酸酐的条件因有或无溶剂而异,有溶剂存在时,反应温度398K,氢压2.0MPa;无溶剂在423K,氢压1.0MPa,顺酐转化率和丁二酸酐的选择性达99.5%以上.     

碳纳米管负载Pd/SnO2催化剂的制备及其催化邻氯硝基苯加氢性能

采用化学还原法制备了不同Sn/Pd摩尔比的碳纳米管(CNTs)负载Pd/SnO2催化剂,并将该催化剂用于邻氯硝基苯(o-CNB)的选择加氢反应.采用透射电镜、X射线衍射和电感耦合等离子体技术对所制备的Pd/SnO2/CNTs催化剂进行了表征.结果表明,Sn/Pd摩尔比对该催化剂的邻氯硝基苯选择加氢反应性能影响显著.当Sn/Pd摩尔比为11时,催化剂的活性最高,在常压,60℃反应60 min,o-CNB转化率为96%.该催化剂还具有高的邻氯苯胺(o-CAN)选择性,o-CNB转化率达到100%时,脱氯副产物苯胺选择性小于5%.在相同条件下,浸渍法制备的2.4%Pd/CNTs催化剂上脱氯副反应严重,当o-CNB完全转化时,o-CAN选择性只有22%,副产物苯胺选择性则高达78%.     

乙酰丙酮钌催化硝基苯氢转移氢化制苯胺

以自制的乙酰丙酮钌配合物（Ru(acac)3）为催化剂,甲酸钠为氢供体,十六烷基三甲基溴化铵为乳化剂,研究了水溶液中催化硝基苯氢转移氢化制苯胺的工艺。 确定了适宜反应条件为：甲酸钠和硝基苯摩尔比为2∶1,反应温度80 ℃,反应时间4.0 h,Ru(acac)3用量为硝基苯质量的4%。 硝基苯的转化率和苯胺产率分别为100%和96.65%,表明Ru(acac)3对硝基苯氢转移氢化制苯胺具有优异的催化作用。     

聚合物稳定的Ru-Pt/γ-Al2O3双金属催化剂催化2,5-二氯硝基苯选择性加氢

 制备了以聚乙烯吡咯烷酮(PVP)稳定的 Ru-Pt/γ-Al2O3负载型双金属催化剂,用于2,5-二氯硝基苯中的硝基选择性加氢. 考察了催化剂还原方法,反应温度、压力、时间和添加金属离子对反应的影响. 结果表明,用乙醇还原的Ru-Pt/γ-Al2O3催化剂性能明显好于用其它方法还原的催化剂,在50 ℃和氢气压力1.0 MPa的条件下反应1 h,转化率为41.4%,生成2,5-二氯苯胺的选择性为63.5%. 如果在上述反应条件下向该催化体系中加入Sn4+离子,反应的活性和选择性则大幅度提高,转化率达100%,选择性为77.6%,延长反应时间至4 h,选择性可达99.3%,并且没有脱氯产物的生成.     

组合型Pt3Sn/Al2O3催化剂用于芳香硝基化合物一锅法合成N-烷基芳胺

采用吸附法制备了组合型Pt₃Sn/Al₂O₃双金属催化剂, 将该催化剂用于芳香硝基化合物原位液相加氢一锅法合成N-烷基芳胺. 研究表明, 在503 K, 空速为7.5 h^-1, 水体积分数为5%时, 1%(质量分数)Pt₃Sn/Al₂O₃催化剂具有较高的催化性能, 硝基苯的转化率为100%, N-乙基苯胺和N,N-二乙基苯胺的总选择性为98.2%. 同时,该催化剂对原位液相加氢烷基化反应具有一定普适性, 本文研究的14 种芳香硝基化合物与低级脂肪醇反应,均具有较高的N-烷基化产率.     

磁性氧化铝负载Pd催化剂对硝基苯加氢催化活性的研究

采用微乳法室温下合成了γ-Al2O3/SiO2/Fe3O4磁性复合颗粒为载体负载的纳米钯催化剂.利用透射电镜、x射线光电子能谱和振动样品磁强计等手段对催化剂进行表征,评价了催化剂对硝基苯加氢制苯胺反应的催化活性.结果表明,通过调控反应条件,可在平均粒径为200nm左右的磁性载体上负载10m左右均匀分散的Pd纳米颗粒,整个催化剂呈现超顺磁性;在催化剂磁含量为8%、Pd负载量1%、反应时间40min、反应温度50℃,反应压力0.5MPa条件下,硝基苯的转化率可以达到100%,催化剂重复使用10次时仍可保持很高的催化活性,并可在外磁场作用下快速分离与回收.     

稀土在聚合物负载铂催化氢化氯代硝基苯反应中的作用研究

研究了稀土元素对高分子负载Pt催化剂催化氢化氯代硝基苯反应的影响. 结果表明 稀土元素的存在抑制了氯代硝基苯加氢反应活性, 对产物氯代苯胺的选择性有不同程度的提高; 碱NaOH存在时, PVP-Pr-Pt给出了90.8%的邻氯苯胺选择性, 使用PVP-La-Pt时得到97.2%的间氯苯胺选择性, PVP-Ce-Pt催化体系获得了98.2%的对氯苯胺选择性.     

水溶性配合物[RuCl2(TPPTS)2]2催化卤代硝基苯选择性加氢

以合成的水溶性钌配合物[RuC l2(TPPTS)2]2作为催化剂,用于水/有机两相体系中催化卤代硝基苯中硝基的选择性加氢反应.以对-氯硝基苯为底物,考察了反应温度、氢气压力、催化剂浓度、水溶液的pH值等对对-氯硝基苯转化率和生成对-氯苯胺选择性的影响.在100℃,氢气压力3.0 MPa时,反应6h,对-氯硝基苯转化率可达100%,生成对-氯苯胺的选择性可达95.2%.该催化剂对其他卤代硝基苯的加氢反应也表现出较高的催化活性.     

One pot synthesis of N-ethylaniline from nitrobenzene and ethanol

A novel method for the one pot synthesis of N-alkyl arylamines from nitro aromatic compounds and alcohols is proposed through the combination of the aqueous-phase reforming of alcohol for hydrogen production, the reduction of nitro aromatic compounds for the synthesis of aromatic amine and the N-alkylation of aromatic amine for the production of N-alkyl arylamine over an identical catalyst under the same conditions of temperature and pressure in a single reactor. In this process, hydrogen generated from the aqueous-phase reforming of alcohols was used in-situ for the hydrogenation of nitro aromatic compounds for aromatic amine synthesis, followed by N-alkylation of aromatic amine with alcohols to form the corresponding N-alkyl arylamines at a low partial pressure of hydrogen. For the system composed of nitrobenzene and ethanol, under the conditions of 413 K and PN2 = 1 MPa, the conversion degrees of nitrobenzene and aniline were 100%, the selectivity to N-ethylaniline and N, N-diethylaniline were 85.9% and 0%-4%, respectivity, after reaction for 8 h at the volumetric ratio of nitrobenzene:ethanol:water = 10:60:0. The selectivity for N, N-diethylaniline production is much lower than that through the traditional method. In this process, hydrogen and aromatic amines generated from the aqueous-phase reforming of alcohols and hydrogenation of nitro aromatic compounds, respectively, could be promptly removed from the surface of the catalyst due to the occurrence of in-situ hydrogenation and N-alkylation reactions. Thus, this may be a potential approach to increase the selectivity to N-alkyl arylamine.     

Hydrogen transfer hydrogenation of nitrobenzene to aniline with Ru(acac)3 as the catalyst

Tris(acetylacetonato)ruthenium(III)(Ru(acac)₃) was synthesized with RuCl₃·nH₂O and acetylacetone as raw materials. The structure of Ru(acac)₃ was identified by FI-IR, ¹H NMR, ¹³C NMR, and elemental analysis. It was used in the catalytic hydrogen transfer hydrogenation of nitrobenzene with sodium formate as hydrogen donor. The effects of reaction conditions on the process, such as temperature, time, dosage of catalyst, and kinds of hydrogen donor, were investigated. The optimal reaction parameters were determined as follows: 80 °C, 4.0 h, the substrate nitrobenzene 20 mL, sodium formate 27.20 g, Ru(acac)₃ 0.96 g, the conversion of nitrobenzene is 100.0 %, the yield of aniline and the selectivity to aniline are 96.65 %. The reaction mechanism is proposed and analyzed. It exhibited excellent catalytic properties in the hydrogen transfer hydrogenation of nitrobenzene to aniline.     

One pot synthesis of <Emphasis Type="Italic">N</Emphasis>-ethylaniline from nitrobenzene and ethanol

A novel method for the one pot synthesis of N-alkyl arylamines from nitro aromatic compounds and alcohols is proposed through the combination of the aqueous-phase reforming of alcohol for hydrogen production, the reduction of nitro aromatic compounds for the synthesis of aromatic amine and the N-alkylation of aromatic amine for the production of N-alkyl arylamine over an identical catalyst under the same conditions of temperature and pressure in a single reactor. In this process, hydrogen generated from the aqueous-phase reforming of alcohols was used in-situ for the hydrogenation of nitro aromatic compounds for aromatic amine synthesis, followed by N-alkylation of aromatic amine with alcohols to form the corresponding N-alkyl arylamines at a low partial pressure of hydrogen. For the system composed of nitrobenzene and ethanol, under the conditions of 413 K and P _N2 = 1 MPa, the conversion degrees of nitrobenzene and aniline were 100%, the selectivity to N-ethylaniline and N, N-diethylaniline were 85.9% and 0%–4%, respectivity, after reaction for 8 h at the volumetric ratio of nitrobenzene:ethanol:water = 10:60:0. The selectivity for N, N-diethylaniline production is much lower than that through the traditional method. In this process, hydrogen and aromatic amines generated from the aqueous-phase reforming of alcohols and hydrogenation of nitro aromatic compounds, respectively, could be promptly removed from the surface of the catalyst due to the occurrence of in-situ hydrogenation and N-alkylation reactions. Thus, this may be a potential approach to increase the selectivity to N-alkyl arylamine. Supported by the Program for New Century Excellent Talents in University (Grant No. NCET-04-0557), and the Specialized Research Fund for the Doctoral Program of High Education (Grant No. SRFDP-20060337001)     

Selectivity in the Phase Transfer Catalytic Hydrogenation of Nitrobenzene by Transition VIII Metals

The phase transfer hydrogenation of nitrobenzene to p-aminophenol has been investigated for the catalysts Pt, Pd, Rh and Ru. The influence of factors such as surfactant concentration, sulfuric acid concentration, hydrogen pressure and temperature on the reaction was determined. It was found that the rate-determining step for the catalytic hydrogenation of nitrobenzene is the catalytic process by which the hydrogen atom is absorbed on the metal surface. A reaction model is suggested which accounts for the observed hydrogenation selectivity and explains how these factors affect product composition and yield. It is shown that Pt favors p-aminophenol production, while Pd favors aniline production.     

复合氧化物催化剂(Cu)CeO2上硝基苯加氢反应的研究

 基于用FT－IR表征H2与硝基苯在催化剂（Cu）CeO2上的吸附和反\r\n应行为，对硝基苯加氢反应进行了研究．结果表明，氢在催化剂表面的\r\n吸附主要为解离吸附，硝基苯的吸附也主要为化学吸附；两种吸附物种\r\n在催化剂上进行表面反应生成易脱附的苯胺，避免了产物与反应物间的\r\n竞争吸附，有利于反应物完全转化．在（Cu）CeO2催化剂上，硝基苯加\r\n氢反应机理为朗格缪尔－欣谢伍德型，即表面反应为控制步骤．     

Cu-Pd/γ-Al_2O_3催化硝基苯和乙醇反应一锅法合成2-甲基喹啉

在5%Cu-5%Pd/γ-Al2O3催化剂作用下,由硝基苯和乙醇反应一锅法合成了2-甲基喹啉.实现了乙醇与硝基苯转移加氢、乙醛缩合、苯胺与不饱和醛加成、脱水环化、脱氢等多步反应的耦合.极大地简化了2-甲基喹啉的合成工艺.相比较传统的化学合成方法,由于避免了使用无机酸碱或均相金属络合物作为催化剂,该方法环境更加友好,解决了均相金属络合物催化剂分离、回收困难的问题.在优化的反应条件:使用1g催化剂,硝基苯15mL,乙醇60mL,水30mL,T=453K,P=3.5MPa,反应时间为12h时,2-甲基喹啉的收率达66.4%.     

纳米镍在硝基苯加氢中催化性能的研究

纳米镍在硝基苯加氢中催化性能的研究左东华，张志琨，崔作林（青岛化工学院纳米材料研究所，青岛２６６０４２）关键词纳米镍，催化加氢，硝基苯．硝基化合物加氢还原是化工生产中的一个重要化工单元反应，现今工业生产中大多采用Ｒａｎｅｙ－Ｎｉ作为催化剂。但由于在Ｒ...     

Ni-B非晶态合金催化剂用于卤代硝基苯液相加氢制卤代苯胺

 用化学还原法制备了Ni-B非晶态合金催化剂,并将其用于4种卤代硝基苯的液相加氢反应. 采用X射线衍射和透射电子显微镜研究了催化剂的非晶性质. 在373 K下处理2 h后催化剂保持非晶态结构,在773 K下处理2 h后催化剂完全晶化. 讨论了Ni-B非晶态合金催化剂的催化性能与其结构之间的关系,并与其它Ni基催化剂进行了比较. Ni-B非晶态合金催化剂不仅具有较高的催化活性,而且对卤代芳胺的选择性较高,脱卤率小于4%,优于其它Ni基催化剂.     

Facile-fabricated iron oxide nanorods as a catalyst for hydrogenation of nitrobenzene

Iron oxide nanorod catalysts were fabricated by wet chemistry method followed annealing. The facilefabricated FeOOH nanorods with an efficient catalytic performance for transfer hydrogenation of nitrobenzene with hydrazine hydrate are presented.