We studied the factors affecting the framework aluminium distribution in the ZSM-5 structure by hydrothermal treatment under different conditions. (27)AlMASNMR, XPS and chemical analysis revealed that with steaming at...We studied the factors affecting the framework aluminium distribution in the ZSM-5 structure by hydrothermal treatment under different conditions. (27)AlMASNMR, XPS and chemical analysis revealed that with steaming at lower water vapor pressure, the framework aluminium located at the external surface is less stable. Steaming at higher water vapor pressure is beneficial in removing the framework Al in HZSM-5, and especially helpful in removing that located at the internal surface of HZSM-5. By changing steaming conditions, one may control the framework aluminium distribution in the HZSM-5 structure.展开更多
This article mainly worked on methods to reduce side reactions of the de-ethylating type catalyst for xylene isomerization. In laboratory the de-ethylating type catalyst for xylene isomerization was subjected to steam...This article mainly worked on methods to reduce side reactions of the de-ethylating type catalyst for xylene isomerization. In laboratory the de-ethylating type catalyst for xylene isomerization was subjected to steam treatment at different temperatures and durations to achieve dealumination of the ZSM-5 zeolite to some extent, which could affect the change in BrФnsted acid content to decrease xylene loss along with reduction of side reactions. Test results showed that the degree for reducing side reactions by steam treatment depended upon two important parameters-treating temperature and duration. The optimal condition required treating the catalyst at 500℃ for 8 hours.展开更多
Isopropylation of naphthalene is a series reaction, which results in a variety of isomers having different alkylation levels.Among them, 2,6-diisopropylnaphthalene （2,6-DIPN） is a raw material for the production of ...Isopropylation of naphthalene is a series reaction, which results in a variety of isomers having different alkylation levels.Among them, 2,6-diisopropylnaphthalene （2,6-DIPN） is a raw material for the production of advanced polyester materials such as PEN and liquid crystal polymers.In this study, the preparation of 2,6-DIPN through the isopropylation of industrial refined naphthalene with propylene was conducted in 0.5 L autoclave with steam dealuminated H-mordenite （SDHM） as the shape-selective catalyst instead of the conventional Friedel-Crafts catalysts and resulted in high selectivity and high yield of 2,6-DIPN.In order to slacken the deactivation of HM, the reaction was carried out in H2 atmosphere.The dehydrogenation of fused-ring polycyclics could be minimized and coke formation could be reduced.The preferred reaction conditions found were temperature of 275—300 ℃,hydrogen pressure of 0.4 MPa,reaction time of 7—8 h and 6%—7% of SDHM by mass,in which no side reactions were observed. From NH3-TPD profiles,it could be seen that the relative strength of strong acid sites of SDHM in hydrogen isopropylation was greater than that in nitrogen isopropylation after the same reaction period.Comparing with the results obtained in nitrogen atmosphere, the conversion of refined naphthalene and yield of 2,6-DIPN could be remarkably increased to an average value as high as 90 % and 35 % respectively.Hence the catalytic activity of SDHM could be maintained for a longer time in H2 atmosphere.展开更多
文摘We studied the factors affecting the framework aluminium distribution in the ZSM-5 structure by hydrothermal treatment under different conditions. (27)AlMASNMR, XPS and chemical analysis revealed that with steaming at lower water vapor pressure, the framework aluminium located at the external surface is less stable. Steaming at higher water vapor pressure is beneficial in removing the framework Al in HZSM-5, and especially helpful in removing that located at the internal surface of HZSM-5. By changing steaming conditions, one may control the framework aluminium distribution in the HZSM-5 structure.
文摘This article mainly worked on methods to reduce side reactions of the de-ethylating type catalyst for xylene isomerization. In laboratory the de-ethylating type catalyst for xylene isomerization was subjected to steam treatment at different temperatures and durations to achieve dealumination of the ZSM-5 zeolite to some extent, which could affect the change in BrФnsted acid content to decrease xylene loss along with reduction of side reactions. Test results showed that the degree for reducing side reactions by steam treatment depended upon two important parameters-treating temperature and duration. The optimal condition required treating the catalyst at 500℃ for 8 hours.
文摘Isopropylation of naphthalene is a series reaction, which results in a variety of isomers having different alkylation levels.Among them, 2,6-diisopropylnaphthalene （2,6-DIPN） is a raw material for the production of advanced polyester materials such as PEN and liquid crystal polymers.In this study, the preparation of 2,6-DIPN through the isopropylation of industrial refined naphthalene with propylene was conducted in 0.5 L autoclave with steam dealuminated H-mordenite （SDHM） as the shape-selective catalyst instead of the conventional Friedel-Crafts catalysts and resulted in high selectivity and high yield of 2,6-DIPN.In order to slacken the deactivation of HM, the reaction was carried out in H2 atmosphere.The dehydrogenation of fused-ring polycyclics could be minimized and coke formation could be reduced.The preferred reaction conditions found were temperature of 275—300 ℃,hydrogen pressure of 0.4 MPa,reaction time of 7—8 h and 6%—7% of SDHM by mass,in which no side reactions were observed. From NH3-TPD profiles,it could be seen that the relative strength of strong acid sites of SDHM in hydrogen isopropylation was greater than that in nitrogen isopropylation after the same reaction period.Comparing with the results obtained in nitrogen atmosphere, the conversion of refined naphthalene and yield of 2,6-DIPN could be remarkably increased to an average value as high as 90 % and 35 % respectively.Hence the catalytic activity of SDHM could be maintained for a longer time in H2 atmosphere.
