汽油异构化改质催化剂的设计与性能调控

发布时间：2018-09-12 08:05

【摘要】：清洁汽油的生产离不开深度加氢,但深度加氢必然造成汽油辛烷值损失。为解决这一矛盾,汽油异构化过程受到日趋关注,而高效异构化催化剂的开发是汽油异构化工艺过程的关键。作为双功能的临氢异构化催化剂,每一组分的功能和组分间的协同作用都将影响催化剂的性能,由此决定了优化酸性组分功能和探究活性金属与酸性载体间相互作用的重要性。本文首先以干凝胶法合成SAPO-11分子筛,通过硅的加入量、CTAB和HF的引入分别调控分子筛的酸量、粒度和形貌;然后以SAPO-11为载体,镍、铂分别为金属组分,采用浸渍法制备了异构化催化剂,考察了金属担载量和酸量对催化剂异构化性能的影响,探究了金属中心与酸中心的协同效应。结果表明,硅在分子筛骨架中的取代量及化学环境决定其酸性质,硅加入量的增加使得硅原子取代方式由SM2取代向SM3发生转换,提高了分子筛的中强酸量。CTAB的加入不仅能降低分子筛粒度,而且因其能促进硅原子发生同晶取代而有利于分子筛酸量的增加,由此提高了Ni/SAPO-11催化剂的活性,但是过高的酸量会破坏Ni与SAPO-11之间的匹配关系,降低异庚烷选择性。HF的加入改变了SAPO-11分子筛的形貌,使其由不规则的颗粒定向生长为棒状单晶,棒状颗粒长度的增加能提高催化剂的异庚烷选择性。此外,分子筛粒度的降低,不仅提高了催化剂的活性,而且也增强了其抗积碳性能。从金属担载量和酸量对Ni/SAPO-11催化剂异构化性能的影响结果可得,两组分间存在着明显的协同关系,酸性中心过多或过分强调金属中心都会降低异构烃的选择性,两活性中心适当匹配,可使催化剂具有优良的异构化性能,其中正庚烷转化率达到73.09%,异庚烷选择性及收率分别为51.16%和37.39%,直馏汽油中异构烷烃收率达到了39.31%。
[Abstract]:The production of clean gasoline can not be separated from deep hydrogenation, but deep hydrogenation will inevitably lead to the loss of gasoline octane number. In order to solve this contradiction, the isomerization process of gasoline has been paid more and more attention, and the development of high efficiency isomerization catalyst is the key to the isomerization process of gasoline. As a bifunctional hydroisomerization catalyst, the function of each component and the synergistic action of each component will affect the performance of the catalyst, which determines the importance of optimizing the function of the acidic component and exploring the interaction between the active metal and the acid support. In this paper, the SAPO-11 molecular sieve was synthesized by xerogel method, and the acid content, particle size and morphology of the molecular sieve were regulated by the addition of Si and HF respectively. The isomerization catalyst was prepared by impregnation method. The effects of metal loading and acid content on the isomerization performance of the catalyst were investigated, and the synergistic effect between metal center and acid center was investigated. The results show that the substitution amount and chemical environment of silicon in molecular sieve skeleton determine its acid properties, and the increase of silicon content makes the substitution of silicon atom change from SM2 substitution to SM3. The addition of CTAB can not only decrease the particle size of molecular sieve, but also increase the amount of acid in molecular sieve because it can promote the isomorphic substitution of silicon atom, thus improving the activity of Ni/SAPO-11 catalyst. However, too high acid content will destroy the matching relationship between Ni and SAPO-11, and decrease the isoheptane selectivity. HF can change the morphology of SAPO-11 molecular sieve and make it grow from irregular particles to rod-like single crystal. The increase of the length of rod-like particles can improve the selectivity of isoheptane. In addition, the decrease of molecular sieve particle size not only improved the activity of catalyst, but also enhanced its resistance to carbon deposition. From the results of the influence of metal loading and acid content on the isomerization performance of Ni/SAPO-11 catalyst, there is an obvious synergistic relationship between the two components. Too much acid center or too much emphasis on metal center will reduce the selectivity of isomerization hydrocarbon. Proper matching of the two active centers can make the catalyst have excellent isomerization performance. The conversion of n-heptane is 73.09, the selectivity and yield of isoheptane are 51.16% and 37.3939%, respectively, and the yield of iso-alkanes in straight-run gasoline reaches 39.31%.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE624.9

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