Platinum(Pt)supported on Zinc(Zn)modified silicalite-1(S-1)zeolite(denoted as Pt-Zn/S-1)was prepared by using a wetness-impregnation method and applied in the n-hexane aromatization reaction for the first time.Both Le...Platinum(Pt)supported on Zinc(Zn)modified silicalite-1(S-1)zeolite(denoted as Pt-Zn/S-1)was prepared by using a wetness-impregnation method and applied in the n-hexane aromatization reaction for the first time.Both Lewis and Bronsted acid sites were detected in Pt-Zn/S-1 catalyst by means of FT-IR adsorption of NH3 experiment,which were identified as mostly weak and medium ones.Besides,Pt and Zn species showed strong interaction,as revealed by the TPR(Temperature-programmed reduction)and XPS(X-ray photoelectron spectroscopy)experiments.Pt-Zn/S-1 catalyst exhibited excellent aromatization function rather than isomerization and cracking side reactions in the conversion of n-hexane.Pulse experimental study showed that 75.6%of n-hexane conversion and 76.8%of benzene selectivity were obtained over Pt0.1-Zn60/S-l catalyst at 550℃ and under atmospheric pressure.By spectroscopy tests and pulse experimental results,it was concluded that the n-hexane aromatization over Pt-Zn/S-1 catalyst follows a metal-acid bifunctional mechanism.Furthermore,with the assistance of Zn,the electron-deficient Pt species in Pt-Zn/S-1 showed good sulfur tolerance performance.展开更多
以正硅酸乙酯为硅源,合成了具有MFI结构的球形和六方片状silicalite-1全硅分子筛,并将其作为载体制备了负载型催化剂用于丙烷脱氢制丙烯反应;采用SEM、XRD、TEM、N_(2)吸附-脱附、Py-FTIR、NH_(3)-TPD、^(29)Si MAS NMR和H_(2)-TPR等方...以正硅酸乙酯为硅源,合成了具有MFI结构的球形和六方片状silicalite-1全硅分子筛,并将其作为载体制备了负载型催化剂用于丙烷脱氢制丙烯反应;采用SEM、XRD、TEM、N_(2)吸附-脱附、Py-FTIR、NH_(3)-TPD、^(29)Si MAS NMR和H_(2)-TPR等方法对两种分子筛载体及负载型催化剂的结构和表面性质进行表征,研究了不同形貌silicalite-1载体对催化剂性能的影响机制。实验结果表明,球形silicalite-1分子筛载体具有更大的外比表面积和更多的表面硅羟基,进而增强了活性组分与载体间的相互作用,提高了活性金属在载体表面的分散度,因此在丙烷脱氢制丙烯反应中球形silicalite-1载体负载的催化剂具有更高的活性。展开更多
Synthesis of high performance Silicalite-1 zeolite membranes on silica tubes was first reported in this paper.After two-step in-situ hydrothermal synthesis,well intergrown Silicalite-1 zeolite membranes were synthesiz...Synthesis of high performance Silicalite-1 zeolite membranes on silica tubes was first reported in this paper.After two-step in-situ hydrothermal synthesis,well intergrown Silicalite-1 zeolite membranes were synthesized on silica tubes after aging at 75 ℃ for 12 h.The Silicalite-1 zeolite membranes were characterized by SEM.The separation performance towards ethanol/water mixtures was evaluated by pervaporation.With temperature increasing,the flux of S-1 membrane,increased from 0.2 kg·m-2·h-1 at 30 ℃ to ca. 1.0 kg·m-2·h-1 at 80 ℃, while the separation factor decreased from 110 to 89.These results showed that silica supports may be more suitable for preparing high performance Silicalite-1 membranes.展开更多
Hierarchical silicalite-1 zeolites were obtained from the direct conversion of a mixture of ground solid raw materials via a steam-assisted crystallization（SAC） method without involvement of any mesoscale template. ...Hierarchical silicalite-1 zeolites were obtained from the direct conversion of a mixture of ground solid raw materials via a steam-assisted crystallization（SAC） method without involvement of any mesoscale template. Only a trace amount of water was necessary during the crystallization, implying that the amount of water can be dramatically reduced, which still offers easy separation and high yields. The simple procedure involved only grinding and heating, which not only saves resources and energy, but also significantly reduces the discharge of eco-friendly synthesis of zeolites for practical applications. Compared to conventional bulk silicalite-1, the nanosized hierarchical zeolites with MFI structure show enhanced removal capabilities for methylene blue owing to their hierarchical porosity.展开更多
基金financially supported by the National Natural Science Foundation of China (21603023)
文摘Platinum(Pt)supported on Zinc(Zn)modified silicalite-1(S-1)zeolite(denoted as Pt-Zn/S-1)was prepared by using a wetness-impregnation method and applied in the n-hexane aromatization reaction for the first time.Both Lewis and Bronsted acid sites were detected in Pt-Zn/S-1 catalyst by means of FT-IR adsorption of NH3 experiment,which were identified as mostly weak and medium ones.Besides,Pt and Zn species showed strong interaction,as revealed by the TPR(Temperature-programmed reduction)and XPS(X-ray photoelectron spectroscopy)experiments.Pt-Zn/S-1 catalyst exhibited excellent aromatization function rather than isomerization and cracking side reactions in the conversion of n-hexane.Pulse experimental study showed that 75.6%of n-hexane conversion and 76.8%of benzene selectivity were obtained over Pt0.1-Zn60/S-l catalyst at 550℃ and under atmospheric pressure.By spectroscopy tests and pulse experimental results,it was concluded that the n-hexane aromatization over Pt-Zn/S-1 catalyst follows a metal-acid bifunctional mechanism.Furthermore,with the assistance of Zn,the electron-deficient Pt species in Pt-Zn/S-1 showed good sulfur tolerance performance.
文摘以正硅酸乙酯为硅源,合成了具有MFI结构的球形和六方片状silicalite-1全硅分子筛,并将其作为载体制备了负载型催化剂用于丙烷脱氢制丙烯反应;采用SEM、XRD、TEM、N_(2)吸附-脱附、Py-FTIR、NH_(3)-TPD、^(29)Si MAS NMR和H_(2)-TPR等方法对两种分子筛载体及负载型催化剂的结构和表面性质进行表征,研究了不同形貌silicalite-1载体对催化剂性能的影响机制。实验结果表明,球形silicalite-1分子筛载体具有更大的外比表面积和更多的表面硅羟基,进而增强了活性组分与载体间的相互作用,提高了活性金属在载体表面的分散度,因此在丙烷脱氢制丙烯反应中球形silicalite-1载体负载的催化剂具有更高的活性。
文摘Synthesis of high performance Silicalite-1 zeolite membranes on silica tubes was first reported in this paper.After two-step in-situ hydrothermal synthesis,well intergrown Silicalite-1 zeolite membranes were synthesized on silica tubes after aging at 75 ℃ for 12 h.The Silicalite-1 zeolite membranes were characterized by SEM.The separation performance towards ethanol/water mixtures was evaluated by pervaporation.With temperature increasing,the flux of S-1 membrane,increased from 0.2 kg·m-2·h-1 at 30 ℃ to ca. 1.0 kg·m-2·h-1 at 80 ℃, while the separation factor decreased from 110 to 89.These results showed that silica supports may be more suitable for preparing high performance Silicalite-1 membranes.
基金Supported by the National Natural Science Foundation of China（Nos.21390394, 21261130584, 91022030, 21771082）, the National Basic Research Program of China（Nos.2012CB821700, 2011CB808703）, the ＂111＂ Project of China（No.B07016）, the Award Project of King Abdullah University of Science ＆ Technology（No.CRG-1-2012-LAI-009）, the Science and Technology Development Center Project of the Ministry of Education of China（No.20120061130012） and the Science and Technology Research Program of the 13th Five Year Plan of China（No.20120061130012） and the Fund of Education Department of Jilin Province, China（No.2016405）.
文摘Hierarchical silicalite-1 zeolites were obtained from the direct conversion of a mixture of ground solid raw materials via a steam-assisted crystallization（SAC） method without involvement of any mesoscale template. Only a trace amount of water was necessary during the crystallization, implying that the amount of water can be dramatically reduced, which still offers easy separation and high yields. The simple procedure involved only grinding and heating, which not only saves resources and energy, but also significantly reduces the discharge of eco-friendly synthesis of zeolites for practical applications. Compared to conventional bulk silicalite-1, the nanosized hierarchical zeolites with MFI structure show enhanced removal capabilities for methylene blue owing to their hierarchical porosity.
