氮掺杂碳凝胶负载钯催化硝基苯加氢制苯胺
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摘要
硝基苯催化加氢是当前工业上制备有机化工原料苯胺的主要方法。以氮掺杂碳凝胶(N-CX)为载体制备了Pd催化剂用于液相硝基苯的催化加氢制苯胺反应。用X-射线衍射、N_2物理吸附对催化剂的物相和织构进行了表征,考察了氮掺杂量、反应压力、反应温度、反应时间对反应活性的影响,并测试了催化剂的多次循环使用性能。结果表明:N-CX具有微孔碳材料的织构性能,作为载体能高分散在其表面的Pd纳米粒子,并在氮/碳前驱体质量比为0.5时制备的N-CX最适宜作为Pd催化剂的载体。反应的最佳条件是H_2压力为1.0 MPa,反应温度为60℃,反应时间为1.0 h。在上述条件下,催化剂显示出一定的循环反应活性,但转化率和选择性随着循环次数的增加有所下降。
Catalytic hydrogenation of nitrobenzene is the main method for the preparation of aniline in organic chemical industry. In this paper, a series of nitrogen-doped carbon gel(N-CX) were used as a support to prepare Pd catalysts for catalytic hydrogenation of nitrobenzene to aniline. The phase and textural structure of the catalysts were characterized by XRD and N_2 physisorption. The effects of nitrogen amount, H_2 pressure, temperature and reaction time on the activity, as well as the long-term stability of catalyst were investigated. Results showed that N-CX has a microporous structure and can highly disperse the Pd nanoparticles on the surface. The N-CX prepared at nitrogen/carbon precursors mass ratio of 0.5 is the most suitable support of the Pd catalyst. The optimum conditions for the reaction are H_2 pressure of 1.0 MPa, reaction temperature of 60 ℃, and reaction time of 1.0 h. Under the above conditions, the catalyst showed a certain cyclic reactivity, but the conversion and selectivity decreased with the increasing of cycles.
Catalytic hydrogenation of nitrobenzene is the main method for the preparation of aniline in organic chemical industry. In this paper, a series of nitrogen-doped carbon gel(N-CX) were used as a support to prepare Pd catalysts for catalytic hydrogenation of nitrobenzene to aniline. The phase and textural structure of the catalysts were characterized by XRD and N_2 physisorption. The effects of nitrogen amount, H_2 pressure, temperature and reaction time on the activity, as well as the long-term stability of catalyst were investigated. Results showed that N-CX has a microporous structure and can highly disperse the Pd nanoparticles on the surface. The N-CX prepared at nitrogen/carbon precursors mass ratio of 0.5 is the most suitable support of the Pd catalyst. The optimum conditions for the reaction are H_2 pressure of 1.0 MPa, reaction temperature of 60 ℃, and reaction time of 1.0 h. Under the above conditions, the catalyst showed a certain cyclic reactivity, but the conversion and selectivity decreased with the increasing of cycles.
引文
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[2]周莲凤,徐宏,杨根山.硝基苯催化加氢制苯胺的技术概况[J].化学工业与工程技术,2007,28(2):39-41.
[3]崔小明.苯胺的生产应用及市场分析[J].上海化工,2002(19):51-53.
[4]BUTOV G M,ZORINA G I,KABLOV V G,et al.Hydrogenation of nitrobenzene with Pd catalysts supported on rare-earth metal oxides[J].Neftepererabotkai Neftekhimiya,2003(5):29-32.
[5]YU X,WANG M,LI H.Study on the nitrobenzene hydrogenation over a Pd-B/SiO2amorphous catalyst[J].Applied Catalysis A:General,2000,202(1):17-22.
[6]TUAEV X,PARAKNOWITSCH J P,ILLGEN R,et al.Nitrogen-doped coatings on carbon nanotubes and their stabilizing effect on Pt nanoparticles[J].Physical Chemistry Chemical Physics,2012,14(18):6444-6447.
[7]WANG Y,YAO J,LI H R,et al.Highly selective hydrogenation of phenol and derivatives over a Pd@carbon nitride catalyst in aqueous media[J].Journal of the American Chemical Society,2011,133(8):2362-2365.
[8]CHAN-THAW C E,VILLA A,PRATI L,et al.Triazine-based polymers as Nanostructured supports for the liquidphase Oxidation of Alcohols[J].Chemistry-a European Journal,2013,17(3):1052-1057.
[9]TANG D,SUN X Y,ZHAO D,et al.Nitrogen doped carbon xerogels supporting Pd nanoparticles for selective hydrogenation reactions:the role of pyridine nitrogen species[J].Chem Cat Chem,2018,10(6):1291-1299.
[10]ZHU J J,XIAO P,LI H L,et al.Graphitic carbon nitride:synthesis,properties and applications in catalysis[J].ACSApplied Materials&Interfaces,2014,6:16449-16465.
[11]XIAO P,ZHAO Y X,WANG T,et al.Polymeric carbon Nitride/Mesoporous Silica composites as catalyst support for Au and Pt Nanoparticles[J].Chemistry-A European Journal,2014,20:2872-2878.
[12]SU D S,ZJANG J,FTANK B,et al.Metal-free Heterogeneous catalysis for sustainable chemistry[J].Chemsuschem,2010,3(2):169-180.
[13]TANG D,YANG L,LI K,et al.Molten salt synthesis of co-entrapped,N-doped mesoporous carbon with CoCl2as template for hydrogen evolution[J].Microporous&Mesoporous Materials,2018,270:274-280.
[14]DONG B,LI Y,NING X,et al.Trace iron impurities deactivate palladium supported on nitrogen-doped carbon nanotubes for nitrobenzene hydrogenation[J].Applied Catalysis A General,2017,545:54-63.
[15]NIE R,MENG M,DU W,et al.Selective hydrogenation of C＝C bond over N-doped reduced graphene oxides supported Pd catalyst[J].Applied Catalysis B:Environmental,2016,180:607-613.
[16]DENG X,ZHAO B,ZHU L,et al.Molten salt synthesis of nitrogen-doped carbon with hierarchical pore structures for use as high-performance electrodes in supercapacitors[J].Carbon,2015,93:48-58.