【作者】 周莉；

【导师】 严新焕；

【作者基本信息】 浙江工业大学 ， 应用化学， 2010， 硕士

【摘要】 有机化合物加氢反应是一类极为重要的反应，在化工生产中占有非常重要的地位。在诸多合成路线中，由于催化加氢具有“三废”污染少、对环境友好、产品质量高等优点而备受关注。现有的催化加氢技术分为氢气还原和氢转移催化加氢法。氢气还原法是利用外加氢气进行催化加氢，但由于氢气易燃易爆且不易储存、运输，成为限制推广氢气还原法这一绿色工艺应用的主要障碍。而氢转移技术是将氢供体(醇、肼、碳氢化合物、有机酸等)提供的活化氢转移到无机或有机化合物中。但该方法原子利用率低、生产成本高。原位液相催化加氢反应是本课题组于2004年提出的一类新的液相催化加氢反应体系，其原理是醇类水溶液重整制得的活化氢，不经过形成分子氢阶段，直接用于有机物的加氢反应，从而克服了液相催化加氢必须使用外加氢气的难点，并且该新反应体系中，氢原子能够100%利用，不但可以利用醇中的氢原子，而且还利用了水分子中的氢原子，从而极大提高氢供体中的原子利用率，符合当今化工生产绿色化的发展趋势(原子经济、环境友好等)，具有工业化应用前景。本论文主要研究了芳香族硝基化合物原位液相催化加氢制备芳胺的反应；重点研究了原位液相催化加氢反应体系中催化剂的稳定性，并对催化剂的失活原因和再生方法进行了探讨；有关研究内容如下：1、制备了Ru-B/C、Ru-Fe-B/C、Ru-Ce-B/C、Ru-Sn-B/C、Ru-Co-B/C等Ru基非晶态催化剂，应用于芳香族硝基化合物的原位液相催化加氢合成芳胺的反应。研究结果表明，所制备的5%(wt)Ru-Sn-B/C(molarRu:Sn=1:3)非晶态催化剂具有较高的催化性能，对邻氯硝基苯原位液相催化加氢的转化率达到99.3 %，无脱卤产生，邻氯苯胺的选择性可以达到99.5%，副产物主要为邻氯羟胺中间体，该催化剂能稳定32h。从非晶态催化剂结构特征、金属原子之间的相互电子转移作用等方面对原位液相催化加氢反应进行了探讨。2、采用浸渍法制备了不同载体不同助剂的Ru基晶态催化剂，用于芳香族硝基化合物的原位液相催化加氢反应。0.5%Ru-2.5%Fe/C催化剂对邻氯硝基苯原位液相催化加氢的转化率达到99.8 %，选择性达到98.0%，该催化剂反应480h后未见明显失活。通过XRD、TEM、XPS等表征手段对0.5%Ru-2.5%Fe/C催化剂的表面特性进行了表征，并考察了反应条件。以表征结果及反应条件对原位液相催化加氢反应的影响为依据，研究了催化剂稳定性提高的原因。3、采用XRD、TEM、XPS、IR、EDS等表征手段研究了催化剂的表面结构、表面电子态、表面吸附情况、原子组成、比表面积和催化剂稳定性之间的关系。经反应机理的研究分析，原位液相催化加氢反应制氢过程中伴随着CO的产生，CO极易吸附于催化剂表面而导致催化剂中毒失活，可通过水汽转化(WGS)和费托合成(FTS)降低CO浓度，提高催化剂的稳定性。研究结果表明Ru-Fe/C催化剂有较高的稳定性，其原因为氧化态的Fe基催化剂在WGS和FTS反应中有高活性及选择性。4、间硝基苯胺是重要的精细化工中间体，通常由间二硝基苯采用硫化碱还原制备。该反应原子经济性低，三废污染大。液相催化加氢获得单硝基部分还原产物的选择性普遍不高。本文通过间二硝基苯原位液相催化加氢反应的研究，在0.5%Ru-2.5%Fe/C催化剂下，间二硝基苯的转化率可达99.4%，间硝基苯胺的选择性为100%。进一步在使用外加氢源的液相催化加氢反应中研究，3.5%Ru16.6Fe83.4/C催化剂在氢气压力为2.0MPa，反应温度为373K，以乙醇为溶剂时，间二硝基苯的转化率为100%，间硝基苯胺的选择性可达98.8%，TOF为0.127s-1。3.5%Ru8.3Ce91.7/C催化剂在此反应条件下，转化率为100%，间硝基苯胺的选择性可达99.4%，TOF为0.364s-1。总之，通过研究发现，原位液相催化加氢反应对一系列的芳香族硝基化合物都具有较好的转化率和选择性，且通过改性或再生可提高催化剂的稳定性。该反应原子利用率高，简化了生产流程，对环境友好，是针对液相催化加氢反应的一大创新，具有重要的科学意义及工业化应用前景。更多还原

【Abstract】 Hydrogenation of organic compounds is an important reaction inindustry. Compared with chemical reductions, catalytic hydrogenation ispreferred currently for the industrial production of many fine chemicalsowing to its lower impact on the environment and the superior quality.Generally, there are two hydrogenation types: catalytic hydrogenationusing molecular hydrogen and catalytic transfer hydrogenation usinghydrogen donors. Catalytic hydrogenation using molecular hydrogen islimited because of the risk associated with the necessity of molecularhydrogen which is easily ignited, exploded and difficult to store andtransport. In the catalytic transfer hydrogenation, active hydrogen can betransferred from hydrogen donors (alcohols, hydrazines, hydrocarbons,organic acids etc) to the inorganic or organic compounds directly.However, its disadvantages are also obvious: relatively low atomic utilization and high cost of products.In-situ liquid catalytic hydrogenation is a novel liquid system ofcatalytic hydrogenation proposed by our group in 2004, in which activehydrogen produced from the reforming of alcohol solution is useddirectly for the hydrogenation of organic compounds, obviating thediffculty associated with the necessity of molecular hydrogen in liquidcatalytic hydrogenation. In the novel reaction system, the utilization ofhydrogen atoms from hydrogen donors is improved greatly because thehydrogen atoms come both from alcohol and water which could beutilized totally with the water-gas shift (WGS) reaction. The novelreaction shows wide application in industry owing to its advantages ofhigh atomic utilization and lower harmful on the environment.In this dissertation, in-situ liquid catalytic hydrogenation of aromaticnitro compounds to corresponding anilines are studied; Speciallyemphasis on the stability of catalysts in the in-situ liquid catalytichydrogenation. Meanwhile, the main reasons of catalyst deactivation andthe methods of catalysts reactived were discussed. Main points of thisdissertation are listed as follows.1. The Ru-B/C、Ru-Fe-B/C、Ru-Ce-B/C、Ru-Sn-B/C and Ru-Co-B/Camorphous catalysts were prepared by chemical reduction and applied inthe in-situ liquid catalytic hydrogenation of aromatic nitro compounds tocorresponding anilines. 5%(wt)Ru-Sn-B/C (molarRu:Sn=1:3) amorphous catalyst exhibited excellent catalytic performance, with the conversion of99.3%, and selectivty of 99.5% for the in-situ liquid hydrogenation ofo-chloronitrobenzene to o-chloroaniline without dehydrohalogenation.The main byproducts were intermediates of halogenated hydroxylamine,the catalyst could be active for 32 hours. The in-situ liquid catalytichydrogenation has been systematically studied based on the structure ofamorphous catalyst, the electronic shift between metallic atoms andreaction conditions.2. The Ru-based catalysts were prepared by impregnation and appliedin the in-situ liquid catalytic hydrogenation of aromatic nitro compoundsto corresponding anilines. The conversion of the in-situ liquid catalytichydrogenation of o-chloronitrobenzene reached to 99.8% and theselectivty to 98.0% over 0.5%Ru-2.5%Fe/C catalyst. The catalyst showssuper stability with more than 480h. The properties of 0.5%Ru-2.5%Fe/Ccatalyst were tested by XRD、TEM、XPS, and the reaction conditionswere studied. Based on the results of catalyst characterization andreaction conditions, the reasons of the catalyst stability were studied.3. The relationship between the catalyst stability and the structure ofcatalyst, the surface electronic state, the surface adsorption, the specificsurface area, the composition of the catalyst, has been systematicallystudied by a series of characterization of catalysts (XRD、TEM、XPS、IR、EDS). In the in-situ liquid catalytic hydrogenation, the active hydrogen produced from the reforming of alcohol solution is alwaysaccompanied with CO production, and the CO could easily adsorb on thesurface of catalyst, which lead to catalyst deactivation attributed topoisoning by CO. The stability of catalyst was improved by water-gasshift (WGS) and fischer-tropsch (FTS) reactions decreasing theconcentration of CO. The Ru-Fe/C catalysts exhibit higher stabiltiy whichis attributed to the FeOx presenting excellent activity and selectivity inWGS and FTS reactions.4. m-Nitroaniline (m-NA) is an important intermediate, the traditionalroute for the preparation of m-NA is based on the use of sulphidesresulting in low atomic utilization and the serious wastes. However, lowselectivity to m-NA is often obtained with liquid catalytic hydrogenationusing molecular hydrogen. Herein, the in-situ liquid catalytichydrogenation was studied. The conversion of the in-situ liquid catalytichydrogenation of m-dinitrobenzene (m-DNB) was 99.4% and theselectivty to m-NA reached 100% over 0.5%Ru-2.5%Fe/C catalyst.Further study was done with the liquid catalytic hydrogenation of m-DNBover 3.5%Ru16.6Fe83.4/C catalyst. With the reaction conditions ofhydrogen pressure of 2.0Mpa, temperature of 373K, ethanol as solvent,the conversion of m-DNB reach to 100% and the selectivty of m-NA to98.8%. On the same reaction conditions, 3.5%Ru8.3Ce91.7/C exhibitedhigher catalytic properties with the conversion of m-DNB was 100% and the selectivty of 99.4%.In conclusion, a series of aromatic nitro compounds could be reducedto corresponding anilines with excellent conversion and selectivity in thein-situ liquid catalytic hydrogenation, and the stability of catalyst can beimproved by modification or reactivation. The in-situ liquid catalytichydrogenation shows high atomic utilization, simplify production processand lower harmful on the environment which opens a new reaction in thefield of liquid catalytic hydrogenation and shows wide applications inindustry.更多还原