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2009年03月31日

【期刊论文】超微NaY分子筛的合成(Ⅰ)添加轻稀土离子的影响

晁自胜, 林海强, 陈国周, 吴廷华, 万惠霖, 闵恩泽

高等学校化学学报,2000,9(21):1353-1358,-0001,():

-1年11月30日

摘要

导向剂的陈化时间和反应胶的晶化温度可以影响NaY分子筛的晶化行为。随导向剂陈化时间的增加,NaY分子筛的晶化速度加快,晶粒尺寸减小;随晶化温度的升高,NaY分子筛的晶化速度加快,但晶粒尺寸增加.而向合成体系中添加轻稀土离子(Ln3+)对NaY分子筛的晶化行为影响更为明显。与未添加稀土离子时相比较,在一定的稀土离子添加量范围内[n(Ln3+)ön(Al3+)<012],NaY分子筛的晶化速度明显加快而晶粒尺寸显著减小,同时所合成出的NaY分子筛的n(SiO2)ön(Al2O3)比也有较大的提高。添加稀土离子使合成体系中形成异晶晶种的Ln(OH)3微晶,从而进一步引发NaY分子筛的成核。

超微分子筛, NaY, 晶体尺寸, 合成, 稀土离子

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2009年03月31日

【期刊论文】Preparation and characterization of hexagonal mesoporous titanium–cobalt oxides

晁自胜, Cheng-Gao Sun a, Li Taoa, Hai-Jun Liang a, Cai-Juan Huang a, He-Sheng Zhai b, Zi-Sheng Chao a, *

Materials Letters 60(2006)2115-2118,-0001,():

-1年11月30日

摘要

Hexagonal mesoporous Co–Ti oxides were synthesized via a supramolecular assembly route, using a non-ionic surfactant, polyoxyethylene fatty alcohol (AEO9). The textural and electronic properties of the specimens were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high resolution transition electron microscopy (HRTEM) and N2-physisorption at 77 K. The application of the mesoporous Co–Ti oxides in the catalytic oxidation of cyclohexane was explored.

Mesoporous material, Titanium–cobalt oxide, Nanomaterials, Sol-gel preparation

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2009年03月31日

【期刊论文】Specific Ion and pH Effects on Supramolecular Assembly of Mesostructured V-Mg Oxides

晁自胜, Zi-Sheng Chao† and Eli Ruckenstein*

Langmuir 2004, 20, 7517-7525,-0001,():

-1年11月30日

摘要

Mesostructured V-Mgoxides were synthesized using the surfactant cetyltrimethylammonium bromide (CTAB) as template, V2O5, V(acac)3 (vanadium acetylacetonate), or NH4VO3 as vanadium source, and Mg(NO3)2, MgCl2, MgSO4, (MgCO3)4

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2009年03月31日

【期刊论文】Phase Behavior of Mesostructured V-Mg-O

晁自胜, Zi-Sheng Chao and Eli Ruckenstein*

Langmuir 2003, 19, 4235-4245,-0001,():

-1年11月30日

摘要

Mesostructured vanadium-magnesium oxides (V-Mg-O) were synthesized using vanadium pentoxide and magnesium nitrate as sources and cetyltrimethylammonium bromide (CTAB) or the mixture of CTAB and hexadecylamine (HDA) as template. The effects of surfactant concentration,pHof the reaction medium, aging time, and temperature as well as aging mode (static or dynamic) were systematically investigated. The pH of the reaction medium and the surfactant concentration and nature were found to be the key parameters in the formation of V-Mg-O mesophases. When CTAB was employed alone as template and its concentration was higher than the critical micelle concentration, single lamellar mesophases were obtained in both acidic and neutral media. When the mixture of surfactants was used as template and its concentration was sufficiently low, only microporous phases were obtained in strongly acidic media (pHe 4), even at elevated aging temperatures and/or for long aging times. A mixture of mesophases could be, however, obtained in weakly acidic and neutral media (pH ) 4-7). At high surfactant concentrations, a single lamellar structure was generated in strongly acidic media and a mixture of mesophases in the weakly acidic and neutral ones. Only amorphous solids were generated in the basic range of pH, regardless of the surfactant concentration employed. With the change in aging time, numerous metastable phases have been identified, particularly in weakly acidic and neutral media.Somecomments about the mechanisms of formation of the mesophases conclude the paper.

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2009年03月31日

【期刊论文】Control of Magnesium Containing Vanadium Mesoporous Materials

晁自胜, Zi-Sheng Chao and Eli Ruckenstein*

Langmuir 2002, 18, 8535-8545,-0001,():

-1年11月30日

摘要

Magnesium containing vanadium mesoporous materials were synthesized using vanadium(V) oxide and magnesium nitrate as sources and cetyltrimethylammonium bromide (CTAB) and the mixture of CTAB andhexadecylamine(HDA)as templates.Theeffects of theMg/Vmolar ratioandthe surfactant concentration in the initial batches, the pH employed, and the length of aging time on the structural properties of the synthesized materials were investigated. Both CTAB alone and the mixture CTAB + HDA were effective in templating magnesium containing vanadium mesoporous materials, with a larger average pore size in the latter case. The degree of crystallinity of the mesoporousV-Mg-Owas found to increase with increasing surfactant concentration in the initial batches. However, a too large amount of surfactant increased tremendously the viscosity of the system, generating difficulties in the preparation. At a given pH, the degree of crystallinity of the mesoporous materials increased with increasing Mg/V molar ratio in the initial batch, attaining a maximum followed by a decrease. At a given Mg/V molar ratio in the initial batch, the degree of crystallinity increased with increasing pH, passed though an optimum for a pH ) 7, and then decreased. The analysis of the composition of the mesoporous materials revealed that the amount of magnesium included in the samples was small and increased only slightly with increasing amount in the initial batches; the increase of the pH increased, however, much more the amount of Mg included in the mesoporous materials. The stability toward heating at various temperatures increased with increasing amount of magnesium in the samples. Possible explanations for the effects found are suggested.

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    湖南大学,湖南

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