新型共晶分子筛催化剂的轻质正构烷烃加氢异构反应性能研究

Although the requirements of the national VI gasoline specification for octane number and the sulfur content remains unchanged, the contents of benzene, olefin and total aromatic hydrocarbons are required to be further reduced for achieving the production of clean oil with high octane number, which impose great challenge to the gasoline hydrofining technology and the corresponding catalyst design. The urgent problem needed to be solved is the high octane loss related to olefin saturation in FCC gasoline derived from hydrogenation process. In order to realize the production of high octane fuel, this proposal focuses on the directional synthesis of the catalysts based on eutectic molecular sieves and novel hierarchical porous materials, which possess the excellent hydroisomerization (ISO) function. Using microporous molecular sieve with different topological structures as the precursor, the material with double microporous structure and the ordered meso-microporous composites could be obtained by eutectic growth method. The related hydroisomerization catalyst was prepared with the active phases of noble metals in fractal confinement dispersion, which resulted in a good sulfur resistance. Furthermore, the systematic researches of adsorption, diffusion and the chemical reaction rules of typical model compounds (n-hexane, n-octane and 1-octene) will be carried out over the as-synthesized catalysts to investigate the inter-relationship between the physico-chemical properties and the catalytic performance of the catalysts. The reaction mechanisms of isomerization reaction will also be explored in details by integrating the DFT calculations with some special analytical techniques of GC-MS, In-situ IR, Raman, NO-DRIFT, and EXAFS, etc. This proposal will lay a sound theoretical and experimental foundation for the practical production of ultra clean fuels.

国VI车用汽油标准虽然对辛烷值及硫含量要求不变，但却大幅度降低苯、烯烃和总芳烃含量，以达到尾气排放及环保要求，这对汽油加氢改质技术及催化剂设计提出了严峻挑战。针对FCC汽油加氢改质后烯烃饱和度高、辛烷值损失较大的问题，为实现高辛烷值清洁油品生产的目标，本申请拟设计合成具有优异加氢异构功能的新型微微孔复合材料催化剂。采用酸性适宜、异构化性能良好的不同拓扑结构微孔分子筛进行双微孔复合或共晶生长合成等级孔道结构材料，制备活性贵金属分形限域的抗硫型加氢异构催化剂。采用动力学方法，考察模型化合物分子(正己烷、正辛烷、正辛烯)在以上复合材料负载型催化剂中的扩散及异构化反应规律，深入探讨材料结构物性与异构化性能之间的相互关系。结合GC-MS、In-situ IR、Raman、EXAFS等分析技术与密度泛函理论(DFT)计算，分析推理加氢异构化的反应机理，为实现清洁汽油生产奠定理论研究和实验基础。

机动车保有量高，燃料油需求量大，造成汽车尾气污染问题日益严重。因此，开发高品质车用汽油是清洁油品生产技术的主要目标。本研究致力于将低辛烷值的正构烷烃通过异构化转化为高辛烷值汽油组分；并定向设计合成酸性适宜、不同拓扑结构和多级孔道的双功能型介微孔复合催化剂，通过优化调变催化剂孔道结构、酸性及理化性质实现催化剂高加氢异构活性和抗硫性。同时，结合系列表征和加氢反应中间及最终产物分析，深入研究了双功能催化剂的构效关系。基于实验结果，开展了密度泛函理论(DFT)计算，研究了不同活性位上汽油中含硫化合物（噻吩、苯并噻吩）的加氢脱硫(HDS)机理。本研究基于实验及理论研究相结合，为实现超清洁汽油加氢催化剂的结构优化及升级换代提供了科学研究基础和指导。