利用嵌段共聚物及无机盐合成高质量的立方相、大孔径介孔氧化硅球

使用非离子型嵌段高分子表面活性剂为模板剂,在无机盐的作用下,合成了直 径在2～4 mm、高度有序、立方相的介孔氧化硅SBA-16球。利用无机盐来调变无机 /有机物种之间的作用力和自组装能力,不仅在介观尺寸上提高了所合成介孔材料 的有序程度,而且在宏观上控制了介孔材料的形貌。经焙烧后的SBA-16球材料比表 面积为750 m~2/g,孔容为0.52 cm~3/g,孔径为7.8 nm。具有大孔径的SBA-16球材 料可以更方便地应用于大分子吸附和分离等领域。     

模板剂和制备条件对介孔CeO2材料性能的影响

在碱性条件下,采用Brij35、Brij35 CTAB、Brij35 PEG20000为模板剂合成了m-CeO2,考察了模板剂种类、合成温度、老化温度及焙烧温度等因素对m-CeO2性能的影响,运用XRD、FT-IR、TEM、N2吸附-脱附和比表面-孔径测定等手段对m-CeO2进行了表征。结果表明,表面活性剂的种类、合成温度、老化温度及焙烧温度对介孔材料的性能有较大影响。以Brij35 CTAB为复合模板剂,合成温度、老化温度及焙烧温度分别为40℃、60℃及450℃时,所制备的m-CeO2-BC,其比表面积、孔容、平均孔径和孔壁厚度分别为137.9m2/g、0.194 cm3/g、4.9nm和0.010nm,且孔径分布较集中,晶粒尺寸为5.9nm,为纳米介孔材料。     

辅助有机胺对介孔分子筛MCM-41合成及其性质的影响

采用阳离子表面活性剂十六烷基三甲基溴化铵为模板剂、硫酸铝为铝源、硅溶胶为硅源，分别使用中等链长的有机胺和正己烷作为辅助添加剂，用水热晶化法在碱性介质中合成了介孔分子筛MCM-41，通过XRD、N2吸附-脱附、SEM测试手段对得到的样品进行了对比表征分析。实验结果表明，除三乙胺外，向反应体系中加入适量的三正丙胺、三正丁基胺、三正辛胺和二异丁胺后，均能够使介孔 MCM-41的d100值和孔径增大，且具有较大的BET表面积（>1 000 m2/g）和孔容（>1 cm3/g）；加入正己烷后，也可以使得MCM-41孔径变大，但是和加入有机胺相比较，合成的样品具有较小的BET表面积（887.3 m2/g）和孔容（0.81 cm3/g）。     

非表面活性剂合成CeO2介孔材料

以非表面活性剂三乙胺(TEA)和聚乙二醇(PEG)为模板剂,合成了具有立方莹石晶相结构的介孔CeO2材料,通过XRD,HRTEM,BET,FTIR和选区电子衍射(SAED)等手段对介孔CeO2进行了表征。考察了模板剂在CeO2介孔结构的形成过程中所起的作用及其对比表面、孔径分布、热稳定性的影响,并对模板剂的作用机制进行了分析。结果表明,三乙胺在CeO2介孔结构的形成中起关键作用,聚乙二醇对介孔结构热稳定性有明显的改善作用,经600℃焙烧3h的样品仍能保持较好的介孔结构,其介孔呈直通型的六方型孔道,比表面积>200m2·g-1,孔分布呈双孔型分布,其中介孔孔径约为5nm左右,微孔孔径在1～2nm之间,介孔占较大比例,并且微孔数量随焙烧温度的升高逐渐减少,直至600℃消失。     

单分散核-壳结构介孔二氧化硅微球的合成

在酸性条件下, 采用非离子表面活性剂嵌段共聚物为模板剂, 季铵盐阳离子表面活性剂为共导向剂, 在预先合成的尺寸均一的单分散实心氧化硅微球表面包裹了有序介孔氧化硅层, 进一步通过高温水热处理, 获得了具有良好分散性和均匀尺寸的介孔壳层(孔径7 nm)氧化硅微球(~500 nm). 氧化硅微球外部包裹的介孔壳层具有较大的比表面积(188 m2/g)和孔容(0.23 cm3/g).     

掺杂TiO2介孔材料的合成与表征

基于溶胶-凝胶过程, 以非表面活性剂有机小分子三乙醇胺为模板剂, 合成了TiO2及Fe3+/V5+-TiO2介孔材料. 利用XRD, TEM, BET, UV-Vis DRS等手段表征了材料的结构、形貌、比表面积、孔径分布及吸光性能. 研究结果表明, 用乙醇萃取法脱除模板剂可形成具有蠕虫状孔道结构的TiO2介孔材料, 而利用焙烧法在450 ℃脱除模板剂时可引起孔道的塌陷. 掺杂Fe3+或V5+可稳定材料的介孔结构, 适宜的掺杂摩尔分数为0.5％. 于450 ℃下焙烧后, 掺杂Fe3+/V5+的TiO2的平均孔径分别为10.5和9.6 nm, 比表面积分别达到103.59和90.80 m2/g. 相对于P25光催化剂, 掺杂Fe3+或V5+的TiO2吸光带边红移至可见光区, 说明掺杂离子在此合成过程中可有效地进入TiO2的晶格结构而引起其微观电子结构的改变.     

Si掺杂介孔SO_4~(2-)/TiO_2的非模板剂法合成及表征

在不使用模板剂的条件下,以工业硫酸氧钛溶液为原料合成介孔偏钛酸前驱体,再经正硅酸乙酯浸渍焙烧制备了具有良好热稳定性的Si掺杂介孔SO42-/TiO2.采用X射线衍射、N2吸附-脱附、扫描电镜、X射线能谱和傅里叶变换红外光谱等表征方法对样品的组成和结构进行了分析,并考察了该材料在亚甲基蓝氧化降解反应中的光催化性能.结果表明,在焙烧过程中,被吸附在偏钛酸孔道内的正硅酸乙酯发生水解,并与偏钛酸孔壁上的自由羟基形成Ti-O-Si键;Si进入二氧化钛骨架中,对孔结构起到了支撑作用,从而提高了介孔SO42-/TiO2的热稳定性.700℃焙烧2 h后,Si掺杂介孔SO42-/TiO2材料的比表面积仍达到189 m2/g,平均孔径为2.8 nm.400℃焙烧的样品在亚甲基蓝降解反应中表现出较好的光催化活性.     

介孔材料B-Al-MCM-48合成的新方法

首次在两种阳离子表面活性剂存在的弱碱反应体系中加入三乙醇胺进行分子调变从而合成了具有较高稳定性和酸性的介孔材料B－Al-MCM-48,并用XRD、IR、TEM、NMR等油试手段对其进行了表征，同时阐述了其合成化学特点。结果表明，实验产品有序度高，介孔排布均匀，孔径大约介于2．0nm-3.0nm,比表面积为1200m^2/g,孔容为1．18mL/g;孔墙中引入的硼以四配位形式存在，改善了沸石酸性和稳定性。进而以轻汽油的催化加氢为探针反应考察了载Ni后介孔材料B－Al-MCM-48的催化活性，与现行X型沸石催化剂载体相比，脱氮、脱硫和芳烃转化大幅度提高。     

铈掺杂的介孔分子筛的水热合成与结构性能

以硅酸钠、硝酸铈铵为原料,十六烷基三甲基溴化铵为模板剂,通过水热法合成铈掺杂的介孔分子筛CeMCM-41.分别采用X射线粉末衍射(XRD)、透射电子显微镜(TEM)、红外光谱(FT-IR)、紫外-可见分光光度计(UV-Vis)和N2吸附-脱附等技术对产物的晶相、结构、形貌、比表面积和孔径进行表征.同时研究硅铈物质的量比对合成材料结构性能的影响.实验结果表明:水热条件下成功合成出铈掺杂的MCM-41介孔分子筛,其比表面积为480.5～1 295.2m2/g,平均孔径在2.70～6.29 nm之间.随着稀土元素铈的掺杂量的增加,CeMCM-41介孔分子筛的比表面积和孔体积变小,介孔有序性变差.     

炭化温度对模板法合成介孔炭性能的影响

以蔗糖为炭源和硅酸钠为硅源,采用原位共聚法制备了炭/氧化硅复合体,除去氧化硅得到介孔炭材料.采用N2吸附-脱附、透射电子显微镜和红外光谱对不同炭化温度获得的样品进行表征.结果表明,随着炭化温度升高,所得的介孔炭比表面积和孔容均下降,650℃ ～ 950℃的炭化温度下获得的样品BET比表面积在586m2/g ～728 m2/g之间,孔容在0.549cm3/g～0.696cm3/g之间,孔径分布5-15nm之间.经红外光谱检测所得的介孔炭样品均含有氢和氧的功能团.     

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。     

中孔沸石新材料MCM－41──Ⅰ．合成、酸性及稳定性

中孔沸石新材料ＭＣＭ－４１──Ⅰ．合成、酸性及稳定性赵修松，王清遐，徐龙伢，谢紊娟（中国科学院大连化学物理研究所，大连１１６０２３）李新生（中国科学院大连化学物理研究所催化基础国家重点实验室，大连１１６０２３）关键词ＭＣＭ－４１沸石，合成，酸性，稳定...     

Three-dimensional low symmetry mesoporous silica structures templated from tetra-headgroup rigid bolaform quaternary ammonium surfactant

Two kinds of highly ordered mesoporous silica materials (FDU-11, FDU-13) with novel three-dimensional (3-D) tetragonal and orthorhombic structures were synthesized by using tetra-headgroup rigid bolaform quaternary ammonium surfactant [(CH(3))(3)NCH(2)CH(2)CH(2)N(CH(3))(2)CH(2)(CH(2))(11)OC(6)H(4)C(6)H(4)O(CH(2))(11)CH(2)N(CH(3))(2)CH(2)CH(2)CH(2)N(CH(3))(3).4Br] (C(3-12-12)(-)(3)) as a template under alkaline conditions. High-resolution transmission electron microscopy (HRTEM), small-angle X-ray scattering (SAXS), and X-ray diffraction (XRD) show that mesoporous silica FDU-11 has primitive tetragonal P4/mmm structure with cell parameters a = b = 8.46 nm, c = 5.22 nm, and c/a ratio = 0.617. N(2) sorption isotherms show that calcined FDU-11 has a high BET surface area of approximately 1490 m(2)/g, a uniform pore size of approximately 2.72 nm, and a pore volume of approximately 1.88 cm(3)/g. Mesoporous silica FDU-13 has primitive orthorhombic Pmmm structure. The cell parameters are a = 9.81, b = 5.67, and c = 3.66 nm. N(2) sorption isotherms show that calcined FDU-13 has a high BET surface area of 1210 m(2)/g, a uniform mesopore size of approximately 1.76 nm, and a large pore volume of approximately 1.83 cm(3)/g. Such low symmetries for 3-D mesostructures (tetragonal and orthorhombic system) have not been observed before even in amphiphilic liquid crystals, which maybe resulted from an oblate aggregation of the bolaform surfactant and its strong electrostatic interaction with inorganic precursor. A probable mechanism has been proposed for the formation of such a 3-D low symmetrical mesostructure. These results will further extend the synthesis of mesoporous materials and may open up new opportunities for their new applications in catalysis, separation, and nanoscience.     

Synthesis of high surface area Al-containing mesoporous silica from calcined and acid leached kaolinites as the precursors

Al-containing mesoporous silicas were synthesized by hydrothermal treatment of microporous silica prepared by selectively acid leached metakaolinites with Si/Al = 3.9-92.5 mixed with a surfactant of cetyltrimethylammonium bromide (CTABr). The specific surface area of the products increased with higher surfactant/microporous silica (surf/Si) ratio and Si/Al ratio of the microporous silica, reaching about 1400 m2/g at CTABr/Si 0.1 and Si/Al 40. The XRD patterns of these products show a hexagonal (100) peak with the lattice parameter a0=4.2-4.3 nm and the N2 adsorption isotherms show steep increase of adsorption between relative pressure of 0.3 and 0.4. Hexagonal mesoporous microstructure is observed by high resolution TEM. The pore size distributions of the products show a sharp peak at 2.8 nm by the BJH method. The high specific surface area of the present mesoporous samples is attributed to the lower matrix density and surface roughness of mesopore wall. The highest specific surface area of the products reached up to 1420 m2/g and this value is apparently higher than those reported in hexagonal mesoporous silicas. A unique microporous structure of the starting material is thought to be related to achieve such a high specific surface area of the products.     

Preparation of mesostructured barium sulfate with high surface area by dispersion method and its characterization

The spherical and cubic mesoporous BaSO(4) particles with high surface area were successfully produced via one-step process through precipitation reaction in aqueous solution of Ba(OH)(2) and H(2)SO(4) with ethylene glycol (n-HOCH(2)CH(2)OH) as a modifying agent. The BaSO(4) nanomaterial revealed that the high surface area and the mesoporous was stable up to 400 degrees C. Agglomerate mesoporous barium sulfate nanomaterials were obtained by the reaction of Ba(2+) and SO(2-)(4) with ethylene glycol aqueous solution. The ethylene glycol was used to control the BaSO(4) particle size and to modify the surface property of the particles produced from the precipitation. The dried and calcined mesoporous BaSO(4) nanomaterials were characterized by X-ray diffraction (XRD), BET surface area and N(2) adsorption-desorption isotherm, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared resonance (FTIR) and thermogravimetric analysis (TGA). The as-prepared mesoporous dried BaSO(4) possesses a high BET surface area of 91.56 m(2) g(-1), pore volume of 0.188 cm(3) g(-1) (P/P(0)=0.9849) and pore size of 8.22 nm. The SEM indicates that the morphology of BaSO(4) nanomaterial shows shell like particles up to 400 degrees C, after that there is drastically change in the material due to agglomeration. Synthesis of mesoporous BaSO(4) nanomaterial is of significant importance for both sulphuric acid decomposition and oxidation of methane to methanol.     

Synthesis of titanium dioxide nanoparticles with mesoporous anatase wall and high photocatalytic activity

Mesoporous titanium dioxide nanosized powder with high specific surface area and anatase wall was synthesized via hydrothermal process by using cetyltrimethylammonium bromide (CTAB) as surfactant-directing agent and pore-forming agent. The resulting materials were characterized by XRD, nitrogen adsorption, FESEM, TEM, and FT-IR spectroscopy. The as-synthesized mesoporous TiO2 nanoparticles have mean diameter of 17.6 nm with mean pore size of 2.1 nm. The specific surface area of the as-synthesized mesoporous nanosized TiO2 exceeded 430 m2/g and that of the samples after calcination at 600 degrees C still have 221.9 m2/g. The mesoporous TiO2 nanoparticles show significant activities on the oxidation of Rhodamine B (RB). The large surface area, small crystalline size, and well-crystallized anatase mesostructure can explain the high photocatalytic activity of mesoporous TiO2 nanoparticles calcined at 400 degrees C.     

溶胶-凝胶技术制备高效液相色谱氧化锆填料

 以氧氯化锆水解得到溶胶,然后以Span－80和Tween－85混合非离子表面活性剂为乳化剂、环己烷为有机相制成W／O型乳状液,用其控制粒度,可得到2～10μm的ZrO2凝胶微球。通过比表面积、孔容、孔径测试及对6种不同性质的物质的吸附试验表明,该微球产物可作为高效液相色谱填料。     

极稀溶液体系中自组装合成纳米介孔氧化硅及其铝修饰材料

在极稀溶液中, 通过改变反应溶剂去离子水的量或原料中铝源的量, 可控合成了不同粒径(20~70 nm)、形貌和孔道结构的纳米介孔氧化硅颗粒和纳米介孔铝掺杂氧化硅材料. 这种材料具有高比表面积(BET比表面积1000 m²/g)和较大的孔容(1.1~1.8 cm³/g). 反应物浓度降低或反应物中添加铝源后, 介孔材料的有序性下降, 粒径减小, 孔容增大, 并产生大量的间隙孔. 通过小角X射线衍射(SAXRD)、透射电镜和氮气吸附-脱附实验表征了样品.