【作者】 王闯；

【导师】 邱介山；

【作者基本信息】 大连理工大学 ， 化学工艺， 2009， 博士

【摘要】 氯代硝基苯加氢合成氯代苯胺是一类重要的有机合成单元反应,具有非常高的工业价值。多年来,高性能氯代硝基苯加氢催化剂的研制和开发一直是研究的热点之一,备受国内外学者的广泛关注。本论文研究了碳纳米管（CNTs）负载Pt及其双金属PtM（M=Fe、Co、Ni、Cu）催化剂催化氯代硝基苯加氢的催化性能,分析了影响Pt/CNTs和PtM/CNTs催化性能的关键因素。针对Pd/CNTs催化剂催化氯代硝基苯加氢选择性低的问题制备了复合型双金属催化剂Pd/SnO₂/CNTs,研究了该催化剂对氯代硝基苯选择加氢的催化性能,考察了影响其催化活性和选择性的主要参数,并分析了该催化剂选择性优于Pd/CNTs的主要原因。针对贵金属资源稀缺、价格昂贵的问题,制备了碳纳米管负载过渡非贵金属Ni、Co催化剂,研究了制备条件对其催化氯代硝基苯加氢活性的影响。此外,初步探讨了碳纳米管负载Ag催化剂在氯代硝基苯选择加氢反应中应用的可行性。研究结果表明,Pt/CNTs及PtM/CNTs双金属催化剂具有很好的邻氯硝基苯选择加氢反应性能。活化温度对Pt/CNTs催化剂粒径大小及氯代硝基苯选择加氢催化性能影响显著。随着活化温度的升高,Pt催化剂平均粒径逐渐增大,催化邻氯硝基苯加氢活性先增加后降低,400℃活化的Pt/CNTs催化剂催化活性最高。对于双金属PtNi/CNTs催化剂,浸渍顺序对其催化性能影响较大:共浸渍法制备的Pt-Ni/CNTs催化剂,其催化活性随着Ni含量的增加逐渐降低;而先浸渍Ni前驱体再还原后浸渍Pt前驱体再还原得到的Pt/Ni/CNTs催化剂催化活性高于单金属Pt/CNTs催化剂,当Ni含量为0.15%时Pt/Ni/CNTs催化剂催化活性最高。采用该方法制备的Pt/Fe/CNTs,Pt/Co/CNTs,Pt/Cu/CNTs催化剂也具有较高的氯代硝基苯加氢催化活性。Pd/SnO₂/CNTs能够有效的抑制o-CAN的脱氯,在保持较高催化活性的条件下,提高目标产物的选择性。Sn/Pd摩尔比是影响Pd/SnO₂/CNTs催化性能的主要参数。Sn/Pd=11时,Pd/SnO₂/CNTs催化剂具有最好的催化活性,在常压60℃反应60min,o-CNB转化率为96%,与相同载量浸渍法制备的2.4%Pd/CNTs催化活性相当。但当o-CNB完全反应完时,Pd/SnO₂/CNTs催化剂上o-CAN的选择性可以达到95%,而Pd/CNTs催化剂上o-CAN的选择性只有22%。SnO₂的调变作用是Pd/SnO₂/CNTs催化剂选择性高的主要原因。Ni/CNTs催化剂表现出较高的氯代硝基苯加氢活性。通过比较浸渍法、水溶液中沉积沉淀法以及多元醇溶剂中沉积沉淀法,发现催化剂的制备方法及条件对其催化加氢性能影响较大。多元醇溶剂中沉积沉淀法制备的Ni/CNTs催化剂催化活性最高。溶剂种类及沉淀温度是影响多元醇溶剂中沉积沉淀法制备NiCNTs催化剂的组成、粒径大小以及o-CNB加氢性能的重要参数。乙二醇为溶剂不同沉淀温度下制备的Ni/CNTs催化剂Ni含量相近;120℃和160℃制备的Ni/CNTs催化剂平均粒径最小,分别为5.1nm和5.7nm,80℃制备的Ni/CNTs催化剂平均粒径较大,为10.7 nm;而80℃制备的Ni/CNTs催化剂催化活性最高,在140℃,2 MPa下反应30 min,o-CNB的转化率达到91%,o-CAN的选择性为97%。丙三醇溶剂中沉积沉淀法制备Ni/CNTs催化剂,Ni含量随着沉淀温度升高而增加,但均低于相同温度下乙二醇溶剂中制备的Ni/CNTs催化剂中Ni含量;Ni/CNTs催化剂的催化活性随着沉淀温度升高而增加,160℃制备的Ni/CNTs催化剂催化活性最高,o-CNB的转化率为72%,o-CAN的选择性为97%。Ni/CNTs催化剂的催化性能优于Ni/AC,其可能的原因是载体与金属之间相互作用不同,并且碳纳米管独特的中孔结构有利于反应的传质。Ag/CNTs催化剂具有一定的氯代硝基苯加氢催化活性。采用沉积沉淀法可以制备催化活性较好的Ag/CNTs催化剂,制备过程中溶液pH值、AgNO₃浓度以及沉淀温度是影响Ag/CNTs催化性能的关键因素。更多还原

【Abstract】 The hydrogenation of chloronitrobenzene to chloraniline is one of the most important organism unit reactions.It is of great industrial value.Therefore,much attention has been paid to the design and synthesis of catalysts with excellent catalytic properties for chloronitrobenzene hydrogenation reactions.In this thesis,the preparation of carbon nanotubes supported metal catalysts and their catalytic performances in the hydrogenation of CNBs have been investigated.Carbon nanotubes supported Pt and PtM（M=Ni,Co,Fe,Cu） catalysts exhibit good o-CNB hydrogenation properties.It is found that the activation temperature is one of the key factors that affect both the nanopartiele size and the catalytic performance of Pt/CNTs.The Pt particles size increases with temperature.Pt/CNTs catalyst activated at 400℃shows the highest catalytic activity in o-CNB hydrogenation reaction.For PtNi/CNTs bimetallic catalysts,the effect of impregnation sequence is found to influence the hydrogenation acitivty remarkably.The catalytic acitivity of Pt-Ni/CNTs catalysts prepared with a fixed Pt loading using the co-impregnation method decreases with Ni loading.However,for the Pt/Ni/CNTs catalysts with Ni loading ranging from 0.05～0.45%,prepared by impregnation of Ni precursor and reduction,followed by the impregnation of Pt precursor and reduction,the catalytic activity is higher than Pt/CNTs catalyst.The catalytic activity is the highest when Ni loading is 0.15%.Pt/Fe/CNTs,Pt/Co/CNTs and Pt/Cu/CNTs catalysts also have excellent activities for o-CNB hydrogenation.Moreover,Pt/CNTs and Pt/M/CNTs catalysts are found to have good selecticity toward o-CAN.Pd/SnO₂/CNTs catalysts with different Sn/Pd molar ratios have been synthesized and tested in the hydrogenation of CNBs.The results show that very good o-CAN selectivity can be obtained over Pd/SnO₂/CNTs catalysts,whereas the catalytic activity depends on the Sn/Pd ratio.Pd/SnO₂/CNTs with Sn/Pd is 11 has the highest activity,with 96%o-CNB conversion at 1 atm and 60℃,which is comparable to that of Pd/CNTs catalyst prepared via the impregnation method.However,the o-CAN selectivity over Pd/SnO₂/CNTs is much higher with 95%o-CAN selectivity when o-CNB is completely consumed,while the o-CAN selectivity is only 22%over Pd/CNTs catalyst.The coordination of SnO₂ is responsible for the relative high o-CAN selectivity.Ni/CNTs are also ideal catalysts for o-CNB hydrogenation reactions.Both the preparation methods and conditions influence the activity of the as-obtained Ni/CNTs catalysts greatly. Based on the comparison results of different methods,it is found that the Ni/CNTs catalyst prepared using deposition-precipitation（DP） in polyol shows the highest catalytic activity. The precipitation temperature and types of solvent are crucial factors that affect the properties of Ni/CNTs catalyst.For Ni/CNTs prepared using DP in ethylene glycol（EG）,the Ni content are similar at different precipitation temperatures,however,the Ni particle sizes as well as the catalytic properties vary a lot.The Ni nanoparticle sizes are smaller for Ni/CNTs prepared via DP in EG at the precipitation temperature of 120℃and 160℃,5.1 and 5.7 nm respectively. Ni/CNTs catalysts obtained at 80℃exhibits the highest activity,the conversion of o-CNB can reach 91%with 97%o-CAN selectivity at 2 MPa,140℃in 30 min.Glycerol has also been used as a solvent to prepare Ni/CNTs catalyst,and the results show that both the Ni content and the catalytic activity increase with the precipitation temperatures.Ni/CNTs catalysts show better activity than Ni/AC,which is probably due to the different metal-support interaction and the unique electronic properties of CNTs.Moreover,the mesepore structure of CNTs also favors the mass transfer of the reactants.Ag/CNTs catalysts have been prepared via deposition precipitation method,and the feasibility of the as-synthesized Ag/CNTs catalysts for o-CNB hydrogenation has been investigated.The results show that the hydrodechlorination can be depressed to some degree over Ag/CNTs catalyst,implying that Ag/CNTs is of potential as selective catalyst for the hydrogenation of CNBs.更多还原