Adsorption equilibria of CH_4 and N_2 on activated carbon andsilica gel were measured for a wide temperature range covering thecritical point: 158-298 K for CH_4, and 103-298 K for N_2. Thedetermination of the compres...Adsorption equilibria of CH_4 and N_2 on activated carbon andsilica gel were measured for a wide temperature range covering thecritical point: 158-298 K for CH_4, and 103-298 K for N_2. Thedetermination of the compressibility factor is shown to haveconsiderable effect on isotherm behavior at conditions after theisotherm maximum. A change in adsorption mechanisms on crossing thecritical temperature was observed in all cases. The kind ofadsorbents and how far the equilibrium temperature to the criticalone are major factors affecting the Transition of isotherms from sub-to supercritical.展开更多
We present the details of the sol-gel processing used to realize inverse silica opal,where the silica was activated with 0.3 mol% of Er3+ ions. The template(direct opal) was obtained assembling polystyrene spheres of ...We present the details of the sol-gel processing used to realize inverse silica opal,where the silica was activated with 0.3 mol% of Er3+ ions. The template(direct opal) was obtained assembling polystyrene spheres of the dimensions of 260 nm by means of a vertical deposition technique. The Er3+-activated silica inverse opal was obtained infiltrating,into the void of the template,the silica sol doped with Er3+ ions and subsequently removing the polystyrene spheres by means of calcinations. Scanning electron microscope showed that the inverse opals possess a fcc structure with a air hollows of about 210 nm and a photonic band gap,in the visible range,was observed from reflectance measurements. Spectroscopic properties of Er3+-activated silica inverse opal were investigated by luminescence spectroscopy,where,upon excitation at 514.5 nm,an emission of 4I13/2 → 4I15/2 of Er3+ ions transition with a 21 nm bandwidth was observed. Moreover the 4I13/2 level decay curve presents a single-exponential profile,with a measured lifetime of 18 ms,corresponding a high quantum efficiency of the system.展开更多
HZSM-5 coating using three colloidal silica binders, acidic colloidal silica （ACS）, neutral colloidal silica （NCS） and basic colloidal silica （BCS）, was prepared to study the effect of hinders on their adhesion ...HZSM-5 coating using three colloidal silica binders, acidic colloidal silica （ACS）, neutral colloidal silica （NCS） and basic colloidal silica （BCS）, was prepared to study the effect of hinders on their adhesion and catalytic activity. Scanning electron microscopy characterization indicated that the zeolite coating using BCS shows the smoothest surface with higher homogeneity and adherence strength. The specific surface area, relative crystallization and acid site strength of zeolites are also dependent on the binder used. Catalytic cracking of supercritical n- dodecane over the series of zeolite coating with various binders indicated that HZSM-5 coating with BCS exhibits the highest and the most stable catalytic activity compared with other kinds of binders, and also exhibits a stable catalytic activity ascribed to its proper acid property and microstructure.展开更多
[Objective] This study aimed to investigate the chemical constituents of Dendrobium thyrsiflorum and determine its bioactive compounds. [Method] The compounds were extracted by 95% alcohol and isolated by column chrom...[Objective] This study aimed to investigate the chemical constituents of Dendrobium thyrsiflorum and determine its bioactive compounds. [Method] The compounds were extracted by 95% alcohol and isolated by column chromatography on silica gel and Sephadex LH-20. Their structures were identified by spectroscopic analysis(1H NMR and13 C NMR). [Result] Seven compounds were obtained and identified as 4, 7-dihydroxy-2-methoxy-9, 10-dihydrophenan-threne(1), syringaldehyde(2),moscatin(3), gigantol(4), batatasin III(5), tristin(6) and stigmasterol(7). [Conclusion] Compounds 1 and 2 were isolated from this medicinal plant for the first time.展开更多
A novel approach is designed to optimize the synthesis of sulfonic-functionalized silica material. Results from 29Si and 27AI NMR suggest that the AI acts as the bridging atom connecting the methanesulfonate and silic...A novel approach is designed to optimize the synthesis of sulfonic-functionalized silica material. Results from 29Si and 27AI NMR suggest that the AI acts as the bridging atom connecting the methanesulfonate and silica matrix. Further pyridine-FTIR spectra followed by catalytic activity tests demonstrate that compared with previous methods, our new approach results in higher Lewis acid site concentration, higher thermal stability and superior catalytic activity. Moreover, the whole catalysis preparation procedure is environmentally friendly. Specifically, the silica matrix is synthesized through hydrolysis of tetrae- thylorthosilicate employing formic acid as hydro-catalyst, in which no surfactant species or precursors were involved.展开更多
基金Supported by the Special Funds of Major State Basic Research Projects (G2000026404) and the National Natural Science Foundation of China (No. 29936100).
文摘Adsorption equilibria of CH_4 and N_2 on activated carbon andsilica gel were measured for a wide temperature range covering thecritical point: 158-298 K for CH_4, and 103-298 K for N_2. Thedetermination of the compressibility factor is shown to haveconsiderable effect on isotherm behavior at conditions after theisotherm maximum. A change in adsorption mechanisms on crossing thecritical temperature was observed in all cases. The kind ofadsorbents and how far the equilibrium temperature to the criticalone are major factors affecting the Transition of isotherms from sub-to supercritical.
基金The work has been supported by the MIUR-FIRB RBNE012N3X,MIUR PRIN, PAT FAPVU 2004-2006,GRICES-CNR.
文摘We present the details of the sol-gel processing used to realize inverse silica opal,where the silica was activated with 0.3 mol% of Er3+ ions. The template(direct opal) was obtained assembling polystyrene spheres of the dimensions of 260 nm by means of a vertical deposition technique. The Er3+-activated silica inverse opal was obtained infiltrating,into the void of the template,the silica sol doped with Er3+ ions and subsequently removing the polystyrene spheres by means of calcinations. Scanning electron microscope showed that the inverse opals possess a fcc structure with a air hollows of about 210 nm and a photonic band gap,in the visible range,was observed from reflectance measurements. Spectroscopic properties of Er3+-activated silica inverse opal were investigated by luminescence spectroscopy,where,upon excitation at 514.5 nm,an emission of 4I13/2 → 4I15/2 of Er3+ ions transition with a 21 nm bandwidth was observed. Moreover the 4I13/2 level decay curve presents a single-exponential profile,with a measured lifetime of 18 ms,corresponding a high quantum efficiency of the system.
基金Supported by the National Natural Science Foundation of China(91116001)
文摘HZSM-5 coating using three colloidal silica binders, acidic colloidal silica （ACS）, neutral colloidal silica （NCS） and basic colloidal silica （BCS）, was prepared to study the effect of hinders on their adhesion and catalytic activity. Scanning electron microscopy characterization indicated that the zeolite coating using BCS shows the smoothest surface with higher homogeneity and adherence strength. The specific surface area, relative crystallization and acid site strength of zeolites are also dependent on the binder used. Catalytic cracking of supercritical n- dodecane over the series of zeolite coating with various binders indicated that HZSM-5 coating with BCS exhibits the highest and the most stable catalytic activity compared with other kinds of binders, and also exhibits a stable catalytic activity ascribed to its proper acid property and microstructure.
基金Supported by Grants from the National Natural Science Foundation of China(No.21202066)the Natural Science Foundation of Yunnan Province,China(No.2012FB156)the Open Research Foundation of Yunnan Key Laboratory of Pharmacology for Natural Products(No.2014G011)
文摘[Objective] This study aimed to investigate the chemical constituents of Dendrobium thyrsiflorum and determine its bioactive compounds. [Method] The compounds were extracted by 95% alcohol and isolated by column chromatography on silica gel and Sephadex LH-20. Their structures were identified by spectroscopic analysis(1H NMR and13 C NMR). [Result] Seven compounds were obtained and identified as 4, 7-dihydroxy-2-methoxy-9, 10-dihydrophenan-threne(1), syringaldehyde(2),moscatin(3), gigantol(4), batatasin III(5), tristin(6) and stigmasterol(7). [Conclusion] Compounds 1 and 2 were isolated from this medicinal plant for the first time.
文摘A novel approach is designed to optimize the synthesis of sulfonic-functionalized silica material. Results from 29Si and 27AI NMR suggest that the AI acts as the bridging atom connecting the methanesulfonate and silica matrix. Further pyridine-FTIR spectra followed by catalytic activity tests demonstrate that compared with previous methods, our new approach results in higher Lewis acid site concentration, higher thermal stability and superior catalytic activity. Moreover, the whole catalysis preparation procedure is environmentally friendly. Specifically, the silica matrix is synthesized through hydrolysis of tetrae- thylorthosilicate employing formic acid as hydro-catalyst, in which no surfactant species or precursors were involved.
