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.
引文
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