Ni-Mo_2N/SiO_2复合纳米催化剂的制备及其对四氢萘加氢的催化活性

Synthesis of Ni-Mo_2N/SiO_2 Nanocomposite Catalyst and Its Catalytic Activity for Tetralin Hydrogenation

采用程序升温氮化法制备了Mo2N/SiO2,在此基础上负载Ni盐,制备了Ni-Mo2N/SiO2复合纳米催化剂,并考察了催化剂对四氢萘加氢的催化活性.结果表明,与Ni2Mo3N/SiO2及Ni/SiO2催化剂相比,Ni-Mo2N/SiO2复合催化剂具有较高的催化活性.采用"分离床"方法研究了Ni和Mo2N对四氢萘加氢活性的影响.通过X射线粉末衍射、透射电镜、氢吸附、元素分析和比表面积测定等技术对Ni-Mo2N/SiO2催化剂进行了表征.结果表明,与Ni/SiO2催化剂相比,Ni-Mo2N/SiO2复合催化剂中Ni的分散度并未提高;催化活性的提高归因于Ni与Mo2N在四氢萘加氢中的协同作用.氮化物的引入增加了芳烃吸附活性位的数目.提出了四氢萘在Ni-Mo2N/SiO2催化剂上的可能加氢机理.

Mo2N/SiO2 was prepared by a temperature-programmed nitridation method. The Mo2N/SiO2 was impregnated with Ni salt solution and then was directly reduced by H2 to prepare a new Ni-Mo2N/SiO2 nanocomposite catalyst. The catalyst was characterized by X-ray diffraction, transmission electron microscopy, H2 chemisorption, ICP-AES, and N2 adsorption-desorption techniques and evaluated by tetralin hydrogenation. The results showed that the new nanocomposite catalyst had higher tetralin conversion than the conventional Ni2Mo2N/SiO2 catalyst or Ni/SiO2 catalyst. The correlation between the active components （Ni and Mo2N） was also studied by the separated-bed method. The synergistic effect of Ni and Mo2N in the Ni-Mo2N/SiO2 catalyst promoted its catalytic activity for tetralin hydrogenation, where Mo2N provided more adsorption sites for aromatics. The possible hydrogenation process of tetralin over the Ni-Mo2N/SiO2 catalyst was proposed.