【作者】 杨晓梅；

【导师】 林励吾；

【作者基本信息】 中国科学院研究生院（大连化学物理研究所） ， 物理化学， 2006， 博士

【摘要】 长链烷烃临氢异构化反应在生产高品质润滑油的过程中发挥着重要的作用,通常它是在具有择形催化性能的金属-酸性双功能催化剂上进行的。本论文制备了不同酸性的Pt/SAPO-11和Pt/MeAPO-11催化剂,并考察了其反应性能,阐述了催化剂中酸功能和加氢/脱氢功能之间的平衡在长链烷烃临氢异构化反应中的重要作用。利用水-醇两相体系合成法可以有效地提高SAPO-11的Si含量和酸量,从而提高它的异构化活性,但过高的酸性失去了与担载Pt的脱氢/加氢功能之间的平衡,导致Pt/SAPO-11的异构化选择性降低。用各种方法表征了不同金属杂原子取代的AlPO-11分子筛并考察了它们在正十二烷临氢异构化反应中的催化性能,发现Pt/MeAPO-11的活性首先取决于MeAPO-11的酸强度,顺序为:Pt/MgAPO-11 > Pt/CoAPO-11 > Pt/ZnAPO-11 > Pt/MnAPO-11,但由于Co和Mn对Pt的较强的相互作用,减弱了担载Pt的金属性能,明显地降低了异构化选择性。本文系统地考察了合成条件对MgAPO-11分子筛的晶相、Mg引入量、酸性和担载Pt催化剂的正十二烷临氢异构化反应性能的影响。研究发现,随着Mg含量的提高,MgAPO-11酸性增强,但由于Mg原子引入骨架产生的较强酸性位Mg-OH-P对Pt的作用,使Pt的金属性减弱,当Mg的含量超过一定值时,Pt的金属性难以与MgAPO-11的酸性相平衡,因此,Pt/MgAPO-11的活性随着Mg含量的提高呈现先增加后降低的趋势。上述研究结果表明,金属性和酸性同时影响催化剂的烷烃临氢异构化反应活性和选择性;只有当两者相互匹配,达到平衡时,才能达到最佳的反应性能。更多还原

【Abstract】 Hydroisomerization of long-chain n-alkanes plays an important role in the process of producing lubricating base oil with high qualities, which is usually carried out over metal-acid bifunctional catalysts with shape-selectivity. In this work, we investigated the catalytic properties of Pt/SAPO-11 and Pt/MeAPO-11 catalysts with different acidities, and elucidated the important role of the balance between the acid function and the (de)hydrogenation function in the hydroisomerization of long-chain n-alkanes.The H2O-alcohol biphase system can effectively improve the Si content, the amount of the acid sites, and thus the activity of SAPO-11 for isomerization. However, due to the acidity of SAPO-11 is too high to balance with the (de)hydrogenation function of the supported Pt, the isomerization selectivity of Pt/SAPO-11 catalyst was decreased.Different metal substituted AlPO-11 molecular sieves were characterized by various techniques, and their catalytic performance was tested in the hydroisomerization of n-dodecane. It was found that the activity of Pt/MeAPO-11 catalysts was primarily determined by the acid strength of MeAPO-11 molecular sieves, and decreased in the order of Pt/MgAPO-11 > Pt/CoAPO-11 > Pt/ZnAPO-11 > Pt/MnAPO-11. Nevertheless, the isomerization selectivity of Pt/MnAPO-11 and Pt/CoAPO-11 was remarkably decreased, because the strong interaction of Mn and Co species with Pt significantly weakened the metallicproperties of Pt.The influence of the synthesis conditions on the crystalline phase, the Mg content, the acidity and the catalytic performance of MgAPO-11 molecular sieves for hydroisomerization of n-dodecane was systematically studied. It was found that the acidity of MgAPO-11 molecular sieves was increased with the increase of the Mg content, whereas the metallic properties of Pt were weakened by the interaction between the Pt and the strong acid sites of Me-OH-P generated by the substitution of Me2+ ions into the framework. Once the Mg content exceeded a certain value, the (de)hydrogenation function of Pt was incapable to balance with the acidity of MgAPO-11 molecular sieves. So the activity of Pt/MgAPO-11 catalysts was increased until the molar ratio of MgO/Al2O3 in the gels was 0.03, and then decreased with the further increase of the Mg content.The above results indicate that in the hydroisomerization of long-chain n-alkanes both the metallic properties and the acidity have effect on the activity and selectivity of the catalysts. Only when the metallic function and the acid function are in proper balance, the catalytic performance of the catalysts is optimum.更多还原