锌锡双金属掺杂MCM-41的合成及表征

以硅酸钠为硅源, 锡酸钠，硝酸锌为金属源，十六烷基三甲基溴化铵为模板剂，采用直接水热合成法合成出了锌锡双金属同时掺杂的介孔MCM-41。通过ICP﹑XRD、TG-DTA﹑FTIR﹑HRTEM以及BET等技术对材料的结构和性质进行了表征。结果表明，合成的材料具有典型的六方介孔结构，比表面高，孔分布窄，热稳定性较高，且锌锡可能进入介孔MCM-41骨架中。该材料对苯酚羟基化反应具有良好的催化性能，双金属修饰MCM-41催化活性明显优于单组分掺杂。     

Studies on Mesoporous Self-Organizing Aluminosilica

A detailed study on the preparation of highly ordered MCM-41 molecular sieves based on our new delayed neutralization process is presented. The rate of acidification does not have an apparent effect on the XRD patterns of MCM-41 but affects the morphology. The synthesized products give a thicker constant wall thickness (about 1.70 nm) of mesopore and a sharp pore size distribution. However, the structural order depends on the carbon chain length, the amount of alcohols as cosurfactants, and the synthetic temperature. A tubular morphology of the MCM-41 material, with hollow tubules 0.3 to 3 m in diameter, can be obtained by careful control of the surfactant–water content and the rate of condensation of silica under high-alkalinity conditions. In tubules-within-a-tubule, the wall of the tubule consists of coaxial cylindrical pores of nanometers characteristic of MCM-41. The hierarchical order structure takes place through a liquid crystal phase transformation mechanism in which an anisotropic membrane-to-tubule phase change is involved.     

Progress in Pore-Size Control of Mesoporous MCM-41 Molecular Sieve Using Surfactant Having Different Alkyl Chain Lengths and Various Organic Auxiliary Chemicals

Pore-size control of mesoporous silica MCM-41 molecular sieve is described on the basis of the use of surfactant having different alkyl chain lengths and various organic auxiliary chemicals during the hydrothermal synthesis process. The BJH pore diameter of MCM-41 can be tuned from 1.6 to 4.2 nm using single or mixture of two surfactant(s) with alkyl chain lengths varied from C₈ to C₂₂. By the addition of different organic auxiliary chemicals: 1,3,5-trimethylbenzene, isopropylbenzene or tridecane into the synthesis medium, the BJH pore size of MCM-41 can be tailored up to 12.0 nm.     

Synthesis of Thermally Stable MCM-41 at Ambient Temperature

A new process to synthesize thermally stable mesoporous molecular sieves of MCM-41 structure based on delayed neutralization at ambient temperature was investigated. All samples synthesized by this new method have BET surface areas of about 1100m²/g and possess high thermal stability up to 900°C. Higher crystallinity and less lattice constriction after calcination were observed for samples with a longer aging period. Those samples with aging time longer than 10 days exhibited four characteristic XRD peaks of MCM-41 both before and after calcination at 560°C. The N₂ adsorption-desorption isotherms of the calcined samples showed larger average pore size and more homogenous pore size distribution. The method was also successfully applied to the synthesis of MCM-41 with different surfactants of hydrocarbon length with 10–18 carbons and proves to be a simple route for obtaining thermally stable MCM-41 at room temperature.     

以CTMABr和CTMAOH为共模板剂合成MCM-41

采用共模板剂水热合成了MCM-41.分别用X射线粉末衍射(XRD)、固体核磁共振(²⁷AlMASNMR)和N₂吸附等温线技术考察了用该方法和传统方法所制备的Si-MCM-41和Al-MCM-41样品的晶相结构、孔结构以及Al在分子筛中的化学环境.结果表明,用共模板剂方法合成的MCM-41样品,其纯度和孔径均一性显著提高,特别是当样品中Al含量较高时,仍可保证Al原子以四配位结合在MCM-41的硅骨架上.还就采用共模板剂的理论依据进行了讨论.     

MCM-41固载胺钯配合物的制备及对Heck反应催化性能的研究

以MCM-41分子筛作为固载材料, 经氨基功能化后与各种钯化合物形成一系列MCM-41载钯配合物, 采用XRD, XPS等技术对其结构及表面性能进行了表征, 研究了催化剂的制备条件等因素对催化Heck芳基化反应性能的影响; 以共轭烯烃和各种芳基碘的Heck芳基化反应考察了MCM～NH₂•Pd(0, II)配合物的催化性能. 结果表明, MCM-41的结构没有被破坏, MCM～NH₂载钯配合物具有较高的催化活性和立体选择性, 在较低的温度(70～90 ℃)下, 可高产率地生成一系列取代的反式产物.     

模板剂对全硅MCM-41介孔分子筛结构的影响

分别采用十六烷基三甲基溴化铵和十六烷基三乙基溴化铵作为模板剂,硅溶胶为硅源,用水热晶化法在碱性（NaOH）介质中合成了MCM-41介孔分子筛样品.通过XRD、N2吸附-脱附、TG-DTA、IR等测试手段对这两种样品进行了对比表征分析.考察了两种不同模板剂对其晶体结构、比表面及孔径大小的影响.实验结果表明,相对于十六烷基三甲基溴化铵做模板剂,采用大头基的十六烷基三乙基溴化铵可以合成较大孔径和孔容（分别为4.72 nm和1.14 cm3•g-1）的MCM-41介孔分子筛,而且具有较窄的孔径分布,因此对于合成大孔径的介孔分子筛MCM-41,十六烷基三乙基溴化铵是一种很好的模板剂.     

中孔硅酸盐材料MCM-41的合成与表征研究(英文)

以十六烷基三甲基溴化铵为模板剂,硅酸钠为硅源,铝酸钠为铝源,在水热条件下成功地合成出了ＭＣＭ－４１中孔硅酸盐材料。采用ＸＲＤ、低温Ｎ２吸附脱附等测试手段对合成的ＭＣＭ－４１样品进行了表征。通过优化合成条件,合成出孔径３.２ ｎｍ、比表面９０４ｍ２／ｇ和孔壁厚约１.４６ ｎｍ的ＭＣＭ－４１分子筛。催化活性测定采用微反应活性实验来评价其活性和选择性。     

MCM-41分子筛的合成及129Xe核磁共振的研究

Purely siliceous MCM-41 with a narrow pore-size distribution, different pore size, high surface area was synthesized . As prepared, calcined and catalytically tested MCM-41 materials have been comprehensively characterized by N₂ adsorption/desorption at 77K and ¹²⁹Xe NMR. By adding mesitylene during the synthesis, the pore size of MCM-41 was enlarged to 5.2nm. The chemical shift in ¹²⁹Xe NMR spectroscopy of adsorbed xenon indicates that the MCM-41 is one dimensional pore channels .     

Phase behavior of binary system of bromobenzene–chlorobenzene confined in SBA-15 and MCM-41

Phase behavior of binary system of bromobenzene-chlorobenzene（C6H₅Br-C₆H₅Cl） confined in SBA-15 and MCM-41（pore diameter 8 nm,3.8 nm,respectively） has been investigated by means of differential scanning calorimetry（DSC）.Phase diagram of C₆H₅Br-C₆H₅Cl system confined in SBA-15 is a type of the complete miscible both in liquid and solid state,the same phase behavior as the bulk system.However,the phase diagram comprises only one boundary line,which is shifted down 22-36 K with respect to the bulk system.C₆H₅Br,C₆H₅Cl or the mixture within nanopores of MCM-41 is nonfreezing.The different phase behavior of the system confined in SBA-15 and MCM-41 is thought mainly due to the relative size of pore to molecule.     

Tuning particle morphology of mesoporous silica nanoparticles for adsorption of dyes from aqueous solution

Spherical and rod mesoporous silica nanoparticles with hexagonal mesostructure were prepared using the modified Stöber method. The morphology, size and internal pore structure can be controlled by simple changing of surfactant concentration and water:ethanol molar ratio. Monodispersed spheroid MCM-41 was obtained at 40 °C under basic conditions using cetyltrimethylammonium bromide (C₁₆TAB) as template. Obtained materials were characterized by X-ray diffraction (XRD), nitrogen physisorption (BET), transmission electron microscopy (TEM) and scanning electronic microscopy (SEM). The results reveal that the pore volume and surface area increase when the amount of C₁₆TAB increases whereas the pore diameter and particle size decrease. However, the use of ethanol as cosolvent led to an increase in the particles’ size. Moreover, the addition of a 3-aminopropyltriethoxysilane greatly influenced the final particle shape. The material was effectively used for the removal of two fluorescent dyes (Hoechst 33342 and rhodamine 6g) from aqueous solution. Adsorption isotherm models, Langmuir, Freundlich and Temkin were used to simulate the equilibrium data. The Langmuir model was found to fit the experimental data better than others models.     

氮气在MCM－41分子筛中的吸附：实验和分子模拟

用美国Micromeritics公司生产的ASAP2010物理吸附仪测定了低温（77 K） N_2在MCM-41分子筛中的吸附等温线，获得了表征MCM-41特征的BET比表面、BJH孔 容和平均孔径。同时用巨正则Monte Carlo（GCMC）模拟方法考究了N_2在MCM-41中 的吸附，得到了N_2在MCM-41中的模拟吸附等温线，分析了流体在MCM-41分子筛中 的微观结构。GCMC模拟中MCM-41介孔材料模型化为圆柱孔，N_2模型化为Lennard- Jones（LJ）球。N_2和MCM-41介孔墙壁间的相互作用采用Tjatjopoulos-Feke- Mann（TFM）势能模型进行表征。通过使模拟和实验结果有一个好的吻合，确定了 一组有效的MCM-41分子筛的势能参数（σ_(ww) = 0.265 nm，∈_(ww)/k = 190 K ）。这为以后其他吸附质在MCM-41中吸附的预测奠定了基础、提供了依据。     

Co掺杂ZnO/MCM-41分子筛的制备及对异戊醇的催化氧化性能

以Co掺杂的介孔分子筛MCM-41为载体, 采用等体积浸渍法制备了系列5%ZnO/xCo-MCM-41催化剂, 并用于催化分子氧氧化异戊醇合成异戊醛的反应. 通过X射线衍射(XRD), 傅里叶变换红外光谱(FTIR), 紫外-可见漫反射光谱(UV-Vis DRS), 扫描电子显微镜(SEM), 氨气程序升温脱附(NH₃-TPD), 氢气程序升温还原(H₂-TPR)和氮气吸附-脱附等手段对样品进行表征, 并考察了Co掺杂量对分子筛结构和催化性能的影响. 结果表明, 随着Co掺杂量的增大, 样品的比表面积和孔体积均减小, 而其平均孔径呈先增大后减小的趋势. 当Co掺杂量为0.05时, 5%ZnO/0.05Co-MCM-41仍保持了MCM-41高度有序的六方介孔结构, 具有高比表面积(989 m²/g)、较大孔径(2.88 nm)和孔体积(0.88 cm³/g), 引入的Co主要以孤立态钴离子[Single-site Co(Ⅱ)]形式存在于MCM-41骨架, MCM-41骨架中的Co可以有效提高ZnO微粒的分散度, 适度降低5%ZnO/MCM-41的表面酸性, 并大幅度提高5%ZnO/MCM-41的氧化还原性. 与5%ZnO/MCM-41相比, 5%ZnO/0.05Co-MCM-41可使异戊醛的选择性提高28.3%.     

Liquid-phase synthesis of isopulegol from citronellal using mesoporous molecular sieves mcm-41 and zeolites

Isopulegol (IPG) was synthesized from citronellal (CTN) at atmospheric pressure and 40~60°C in a batch reactor by using mesoporous molecular sieves MCM-41 as well as zeolites HZSM-5 and Hβ. The catalysts were characterized by the methods of XRD, N₂ adsorption, ²⁷Al and ²⁹Si MAS-NMR and TPD of ammonia. Under our reaction conditions, Al-MCM-41 was found to be the best catalyst; it exhibited much higher activity, despite slightly lower IPG selectivity. The catalytic results depend on a variety of factors, viz. the acidity, the pore size and the pore channel of catalysts. The reaction paths were proposed and the kinetic parameters for competitive first order reactions of CTN were estimated. This revised version was published online in June 2006 with corrections to the Cover Date.     

Preparation of MnCo/MCM-41 catalysts with high performance for chlorobenzene combustion

MCM-41 was synthesized by a soft template technique. The specific surface area and pore volume of the MCM-41 were 805.9 m²/g and 0.795 cm³/g, respectively. MCM-41-supported manganese and cobalt oxide catalysts were prepared by an impregnation method. The energy dispersive X-ray spectroscopy clearly confirmed the existence of Mn, Co, and O, which indicated the successful loading of the active components on the surface of MCM-41. The structure and function of the catalysts were changed by modulating the molar ratio of manganese to cobalt. The 10%MnCo(6:1)/MCM-41 (Mn/Co molar ratio is 6:1) catalyst displayed the best catalytic activity according to the activity evaluation experiments, and chlorobenzene (1000 ppm) was totally decomposed at 270 °C. The high activity correlated with a high dispersion of the oxides and was attributed to the exposure of more active sites, which was demonstrated by X-ray diffraction and high-resolution transmission electron microscopy. The strong interactions between MnO₂, Co₃O₄, MnCoO_x, and MCM-41 indicated that cobalt promoted the redox cycles of the manganese system. The bimetal-oxide-based catalyst showed better catalytic activity than that of the single metal oxide catalysts, which was further confirmed by H₂ temperature-programmed reduction. Chlorobenzene temperature-programmed desorption results showed that 10%MnCo(6:1)/MCM-41 had higher adsorption strength for chlorobenzene than that of single metal catalysts. And stronger adsorption was beneficial for combustion of chlorobenzene. Furthermore, 10%MnCo(6:1)/MCM-41 was not deactivated during a continuous reaction for 1000 h at 260 °C and displayed good resistance to water and benzene, which indicated that the catalyst could be used in a wide range of applications.     

杂原子介孔Ce-MCM-41分子筛的制备及其吸附脱除甲硫醚性能

以十六烷基三甲基溴化铵为模板剂,正硅酸乙酯(TEOS)为硅源,硝酸铈为铈源,采用水热法合成了杂原子介孔分子筛Ce-MCM-41。XRD和FT-IR表征结果表明,当加入的Ce/Si物质的量比小于0.04时合成了规整有序的介孔结构,并将Ce原子引入到MCM-41骨架中。N₂吸附-脱附测试获得MCM-41和Ce-MCM-41(Ce/Si物质的量比为0.04)的平均孔径分别为2.82和2.46 nm,孔容分别为0.762 1和 0.689 4 m³/g,BET比表面积分别为986.42和756.8 m²/g。NH₃-TPD表征结果表明,Ce-MCM-41的酸性要明显强于MCM-41,但两种分子筛的酸性均较弱。利用合成的MCM-41和Ce-MCM-41吸附脱除甲硫醚浓度为58 μg(甲硫醚)/g的甲硫醚/氮气混合气中的甲硫醚。甲硫醚分子尺寸的模拟结果为0.464 8 nm,可以很容易地进入分子筛的介孔孔道中。由于Ce-MCM-41分子筛具有较多的酸量,其硫吸附容量7.52 mg(S)/g明显高于MCM-41的4.57 mg(S)/g。MCM-41和Ce-MCM-41都具有较好的再生性能,再生3次后硫吸附容量仍可恢复到初始容量的80%,分别为3.52和 5.86 mg(S)/g。     

Hβ/MCM-41复合分子筛催化剂上苯甲醚与乙酸酐酰化反应研究

以β沸石为硅源,制备了不同硅铝比的Hβ/MCM-41复合分子筛,考察了该复合分子筛对苯甲醚与乙酸酐酰化反应的催化效果,并与介孔MCM-41、微孔Hβ分子筛的催化效果进行了比较,研究了分子筛硅铝比、酸性及孔道结构对酰化反应催化性能的影响。结果表明,对于苯甲醚和乙酸酐酰化反应,Hβ/MCM-41复合分子筛具有较好的催化稳定性,反应过程中的积炭量较少,积炭的碳氢比较低。该复合分子筛不仅具有微孔沸石的强酸性,而且具有较大孔径的介孔,产物分子能及时从孔道中扩散出来,催化活性位不易中毒失活。     

(MCM-41)-La_2O_3纳米复合材料的制备、表征及光学性质

借助水热法,以正硅酸乙酯为硅源,十六烷基三甲基溴化铵为模板剂,在碱性条件下制备了纳米MCM-41分子筛。通过固相热扩散法将La2O3组装到MCM-41介孔孔道中,制备出含La2O3不同浓度的(MCM-41)-La2O3主-客体纳米复合材料。采用化学分析、粉末XRD、FTIR、77K低温N2吸附-解吸附、固体扩散漫反射吸收光谱、拉曼光谱、扫描电镜和发光光谱对主-客体复合材料进行表征。粉末XRD结果表明,La2O3组装到MCM-41分子筛的孔道后并未破坏分子筛骨架,在所制备的(MCM-41)-La2O3主-客体纳米复合材料中MCM-41骨架结构仍然具有较高的有序性,并且,随着植入客体材料浓度的增加复合材料的有序度有所降低。红外光谱表明所制备的纳米复合材料主体分子筛骨架完好;低温氮气吸附-解吸附技术表明La2O3已经部分地占据了MCM-41分子筛孔道,导致分子筛的比表面积和孔体积都有所降低;固体扩散漫反射吸收光谱表明吸收光谱的吸收峰发生了蓝移现象,并表现出量子限域效应,说明La2O3已经组装到了MCM-41分子筛的孔道中;拉曼光谱表明所制备的复合材料没有出现新的特征峰,表明La2O3已经组装到了MCM-41分子筛的孔道中;扫描电镜表明(MCM-41)-La2O3样品的外观非常规整,主要呈现的是球状结构,La2O3含量为10%时,(MCM-41)-La2O3的平均粒径为(114±10)nm。发光光谱研究结果表明,所制备的复合材料(MCM-41)-La2O3样品在396nm处具有较好的发光性质,因而具有作为发光材料潜在应用前景。     

水热法合成MCM-41分子筛时添加辅助烃的影响

０前言中孔ＭＣＭ－４１分子筛是Ｍｏｂｉｌ公司１９９２年开发的一种具有２－１０ｎｍ孔径的新型分子筛材料。由于其独特的孔径范围和表面特性,相关研究已经成为国际分子筛研究领域的热点课题,对它的合成、表征和催化作用已进行了许多研究［１～７］。Ｍｏｂｉｌ公司的...     

Study of the Adsorption Properties of MCM-41 Molecular Sieves Prepared at Different Synthesis Times

The variation of surface properties of SiMCM-41 and AlMCM-41 nanoporous materials as function of synthesis time was examined. The main properties studied were: surface area, pore diameter, pore volume, mesoporous parameter, and wall thickness. Siliceous MCM-41 molecular sieves were synthesized starting from hydrogels with the following molar compositions: 4.58SiO₂:0.435Na₂O:1 CTMABr:200 H₂O for SiMCM-41, and 4.58SiO₂:0.485 Na₂O:1 CTMABr:0.038 Al₂O₃:200 H₂O, for AlMCM-41. Cetyltrimethylammonium bromide (CTMABr) was used as the structural template. The crystallographic parameters were obtained from XRD data and by nitrogen adsorption using the BET and BJH methods. The results obtained showed a significant variation of the surface properties of the MCM-41 materials as a function of the synthesis time reaching silica wall thickness of ca. 2 nm on the fourth day.