| Since the effective resource utilization and the environmental protection are received recognition widely, the researchers in chemistry pay more and more attention to making clean liquid fuels from the coal, the nature gas and the biologic matters. At present, such conversion process as follows is adopted in industry:As one of the efficient and clean techniques to utilize the coal, the FT synthesis is received attention worldwide. But n-paraffins are the main products in the traditional FT synthesis, in which the gasoline and its octane number are low. With the discovery of the ZSM-5 zeolite and its application to the traditional FT synthesis, the FT synthesis technique has been successfully developed and enhanced, and the yield of the gasoline in the products has been increased by using this modified FT synthesis (MFT). However, as one of its disadvantages, this kind of gasoline octane number increase in MFT is mainly due to the arene in gasoline. In recent years, the arene's content in gasoline need to be reduced, for the severe criterions of the environmental protection. Generally, the octane number can be increased by improving the proportion of iso-paraffins. Therefore, the hydroisomerization reaction, as one of the techniques in isomerization reactions, has been gained great attention.The iso-paraffins of C4-C8 are the hydrocarbons with high octane numbers, which are used as fuels for internal-combustion engines and fuel batteries. By further hydrocracking and isomerizing the synthesis oil, the iso-paraffins of low carbon chains with high octane numbers will be produced. Consequently, the octane number of the gasoline will be increased at the same time.As a model reaction of the isomerization reactions and the cracking reactions of the FT oil, the n-C7H|6 hydrogenation reaction is used to selectively control such kind of reactions.To date, the researchers in chemistry have developed a series of rather ideal catalysts for the hydroisomerization reactions of the paraffins with short carbon chains, such as the n-C5/C6-However, with the addition of the carbon numbers, those n-paraffins whose carbon numbers exceed that of the n-C7H16, could hydrocrack easily, and as a result, the selectivity of the iso-paraffins decline. Therefore, the key to the hydroisomerization reactions of this kind of n-paraffins is how to increase the selectivity of the iso-paraffins by reducing the activity of the cracking reactions.Therefore, the double-function catalysts composed of noble metals and zeolites were used in our research and the effects of the reaction condition, the metal/zeolite catalyst composition and their contacting manner on the n-C7H16 hydroisomerization reaction were investigated. As an outline, the main contents of this dissertation are as follows:(1) The effect of the reaction condition on the n-C7H16 hydroisomerization reaction was studied. As a result, it was found that the isomerous selectivity was reduced with theincrease of the temperature and improved with the decline of the rate of either W/F or H2/C7. Besides, the isomerous selectivity can also be enhanced by increasing the system pressure or the partial pressure of the hydrogen.(2) The effect on the n-C7H16 hydroisomerization reaction of the different noble metals loaded on the zeolite was also studied. By comparing the difference between the n-C7H16 hydroisomerization reactions under different systems, such as Pt/ZSM-5 with Pd/ZSM-5 and Pt/USY with Pt/USY, the effect of the activity of the metal center on the n-C7H16 isomerization was investigated. As one of the results, the selectivity of the isomerization reaction was strengthened by using Pt, for Pt loaded on the zeolite carrier has stronger activity of the hydrocracking reaction than that of Pd.(3) In addition, the capability and the path of the n-C7H16 hydroisomerization reaction using different structural zeolites loaded noble metals were studied.(4) The effect of the different mechanical mixture rates of Pd/SiO2 and USY on the n-C7H16 hydroisomerization reaction w... |
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