介孔二氧化锆分子筛比表面和孔结构的调变

在非离子表面活性剂PEO作用下，用固态反应结构导向法合成了介孔二氧化锆。根据Zr-O-Zr骨架结构与有机物种键合较弱的特点，使用了溶剂抽提法脱除结构导向剂。结果发现该法所得介孔材料与焙烧法所得结构显著不同，溶剂抽提法所得材料具有丰富的介孔结构，且比表面较高；而焙烧法所得样品为超微孔结构，热稳定性较高，SEM结果表明在较高的焙烧温度下其有序的表观形貌依然存在。     

CMC和CTAB双模板法合成具有稳定结构的MCM-41中孔分子筛

以羧甲基纤维素和十六烷基三甲基溴化铵为双模板,制备出了具有更高稳定性并且具有高度有序二维六方结构的MCM-41介孔分子筛.透射电镜和X射线衍射结果表明,以双模板制备的MCM-41介孔分子筛具有高度有序的二维六方(p6mm)孔道结构.此外,以双模板制备的MCM-41介孔分子筛焙烧前后的X射线衍射结果表明,在焙烧过程中其晶胞收缩比例为3.1%.与以纯表面活性剂为模版制备的MCM-41介孔分子筛(晶胞收缩比例为9.7%)相比,双模板制备的MCM-41介孔分子筛具有更高的稳定性能. MCM-41介孔分子筛稳定性能的提高可能是由于在硅物种、表面活性剂以及羧甲基纤维素在自组装过程中,羧甲基纤维素表面丰富的羟基与硅物种Si-(OH)x的相互作用促进了Si-(OH)x的缩聚.     

高温水热合成具有高稳定性的有序介孔材料

高温水热合成路线作为合成具有超高稳定性的介孔材料越来越受到人们的重视.本文对高温水热合成有序介孔材料的发展过程作一个简单的综述,合成路线包括使用碳氟表面活性剂和碳氢表面活性剂作为复合模板,有机季铵盐与碳氢表面活性剂作为复合模板以及最近报道的采用碳氢表面活性剂作为单一模板来合成系列的有序介孔材料,其组成为二氧化硅、氧化钛硅以及聚合物等.     

阴离子表面活性剂辅助模板途径合成介孔结构氧化锆纳米晶

利用阴离子表面活性剂十二烷基磺酸钠(SDS)为辅助模板剂, 成功地合成了高稳定性的介孔氧化锆纳米晶, 采用DSC-TG, FT-IR, XRD, TEM, UV-Vis以及N₂吸附-脱附等方法对样品进行了表征. 研究表明, 以阴离子型十二烷基磺酸钠合成的氧化锆经600 ℃煅烧后仍为纯四方相, 氧化锆晶粒平均尺寸约为6.5 nm. 阴离子型表面活性剂与有机锆源形成自组装协同作用, 合成的氧化锆具有蠕虫状介孔结构, 经过500 ℃煅烧后介孔结构仍然保持, 且由于表面活性剂的去除, 比表面积显著提高, 显示了良好的热稳定性. 本实验制备的氧化锆纳米晶较一般方法制备的市售纳米氧化锆有明显紫外吸收边蓝移现象.     

阴离子表面活性剂为模板合成双重介孔结构二氧化硅

本文报道以阴离子表面活性剂十二烷基肌氨酸钠为模板,合成具有层状结构和蠕虫状介观结构的双重介孔二氧化硅颗粒．这些颗粒的尺度在300～50011111,氮气吸附表明其比表面为536m^2/g,孔体积为0．83cm^3／g,具有3nm和12nm的双重介孔分布．层状结构形成可归因于表面活性剂形成的层状液晶相模板,而无序蠕虫相是由表面活性剂柱状液晶相模板诱导形成的．层状液晶相的产生可归因于部分质子化的羧酸表面活性剂诱导的柱状相到层状相的转化．     

以TEA为模板剂合成二氧化锆介孔分子筛热稳定性的研究

以丙醇锆为锆源、有机小分子三乙醇胺作为络合稳定剂和模板剂,通过水热合成途径制备了二氧化锆介孔分子筛.在不引入任何其他辅助离子的前提下,所得样品具有较好的热稳定性.通过TG-DTA,XRD,TEM等表征手段,考察了不同焙烧温度对二氧化锆介孔分子筛结构的影响,并对其机制进行了初探.     

介孔丝光沸石的制备及其对重芳烃转化反应的催化性能

 用不同浓度的 NaOH 溶液对丝光沸石进行处理制备了具有复合孔道结构的介孔丝光沸石, 并采用 X 射线衍射、扫描电子显微镜、透射电子显微镜和 N2 吸附-脱附等方法对其进行了表征. 结果表明, 随着 NaOH 溶液浓度的升高, 介孔丝光沸石的粒径逐渐变小, 分子筛表面的介孔逐渐丰富, 孔径分布逐渐变宽, 介孔体积逐渐增大呈线性关系. 当 NaOH 浓度为 0.50 mol/L 时, 介孔丝光沸石的形貌变为空心沸石微囊或微囊壁. 介孔的增加产生扩散效应, 适当的 NaOH 溶液处理有利于提高丝光沸石对 C9 和 C10 芳烃的转化能力.     

利用廉价硅酸盐为硅源合成介孔SiO2球

利用廉价的硅酸盐为二氧化硅前驱体,以非离子和阳离子表面活性剂为混合模板剂合成微米级的介孔二氧化硅。控制非离子和阳离子表面活性剂的量可以得到分散性较好的介孔二氧化硅球,其平均颗粒直径为2．5μm,平均孔径为3．25nm,比表面为1379m^2／g,孔体积高达1．12cm^3／g。实验讨论了两种表面活性剂的比例对介孔二氧化硅形貌和介相结构的影响,并用混合模板机理解释了不同形貌形成的原因。     

以伯胺为模板剂合成含铁介孔分子筛FeHMS

以非离子型表面活性剂伯胺为模板剂合成了含铁介孔分子筛FeHMS,并对其结构和形态进行了表征。发现FeHMS的颗粒比SiHMS小,粒子表面更为光滑。除了2.5nm的介孔外,FeHMS还原10nm左右的孔。FeHMS介孔分子筛在脱除模板剂之前,铁主要处于四面体配位状态的骨架位,经焙烧脱除模板剂之后,部分铁由骨架位迁移到孔壁表面。用酸化的乙醇溶液抽提脱除模板剂,能更有效地让铁保留在四面体配位状态的骨架位上。高温脱除模板剂后,孔壁表面的铁物种处于一种高分散的状态。此外还研究了HMS类介孔分子筛材料的水热稳定性,发现铁的引入可改善介孔分子筛材料的水热稳定性。     

高热稳定性介孔氧化锆的合成及表征

利用阴离子表面活性剂作模板,通过水热均匀沉淀方法成功合成了具有高热稳定性的介孔氧化锆.该方法以十二烷基苯磺酸钠(SDBS)作为介孔结构的导向剂,其含S基团在煅烧时起到了稳定剂的作用.采用透射电镜、氮气吸附-脱附、X射线粉末衍射、红外光谱测试手段对样品进行了表征.研究表明,以SD-BS为模板剂合成的介孔氧化锆具有蠕虫状介...     

Synthesis and Characterization of Zirconia Nanocrystallites by Cationic Surfactant and Anionic Surfactant

1 INTRODUCTION Zirconia is a kind of metallic oxide with high mel- ting point. It is highly corrosion-resistant for acid fu- sant and neutral fusant, thus it can be used as refrac- tory material, and it can also be utilized as acid acy- loxy bi-functional catalystic material owing to hav- ing both acid and alkali surface centers[1]. Moreover, zirconia has superior ion-exchange capacity as well as chemical and mechanical stability, therefore, it can also be applied as a catalyst carrier. …     

超临界条件下合成晶型骨架的介孔氧化锆

采用聚氧乙烯型非离子表面活性剂(PEO)为模板剂,超临界乙醇为介质,在不同条件下(各种PEO,不同pH值和络合剂)合成了类似于MSU的介孔氧化锆.XRD,N₂物理脱吸附曲线,TEM及选区电子衍射证明该介孔氧化锆骨架为四方晶型;改变表面活性剂类型、络合剂及pH可调变介孔氧化锆的BET表面积与孔分布.     

钙掺杂介孔氧化锆的合成及其表征

室温下1.5 mmol·L^-1硫酸铵溶液体系中,以阳离子型表面活性剂十六烷基三甲基溴化胺为模板,四水硫酸锆为无机前驱体,按照配位体辅助模板机理合成介孔氧化锆前驱体。通过液相后移植工艺实现了钙对氧化锆的掺杂改性。借助XRD、TEM、UV-Vis、XPS、N₂吸-脱附及室温荧光光谱(RTPL)等方法对样品进行了表征分析。研究表明,钙离子进入氧化锆骨架结构中,掺杂改性后的氧化锆具有很强的荧光特性,其孔径尺寸在2.2 nm左右。     

Synthesis of thermally stable zirconia-based mesoporous materials via a facile post-treatment

A novel method of preparing thermally stable zirconia-based mesoporous materials was developed. The zirconia-based mesoporous materials of 2D-hexagonal structure were prepared using zirconium sulfate as the zirconium precursor and cetyltrimethylammonium (CTMA) as the pore-directing agent with the aid of salt in the synthesis solution to reduce the sulfate content in the final product and significantly improve the crystallographic ordering. Post-treatment of the mesoporous material with NaCl solution and lowering the ramping rate to less than 0.2 degrees C/min during the calcination process, however, were the key steps to hinder the growth of the dense zirconia phase and to retain the ordered mesostructure up to 600 degrees C. It was found that a portion of the surfactant (8.9-17.4 wt %) and sulfate ions (0.5-1.2 wt %) were removed during the post-treatment, which prevented the remaining sulfate groups from being reduced by the hydrogen-rich surfactant during the calcination process as confirmed by sulfur K-edge X-ray absorption near edge structure (XANES) and infrared spectroscopy. The maintenance of sulfur in the sulfate state seemed to be important in stabilizing the mesoporous structure of zirconia materials. The mesoporous zirconia materials after extraction with NaCl solution three times and calcination at 550-600 degrees C had the composition ZrO(2-x)(SO4)x with x = 0.10-0.27. The material possesses high surface area (approximately 200 m2/g), large pore volume (approximately 0.10 cm3/g), and wormlike mesopores. In comparison with the mesoporous zirconia materials stabilized by chemical treatment, the present route was simpler and more environmentally friendly and resulted in mesoporous zirconia materials of better thermal stability.     

Synthesis of silica particles with lamellar and wormhole-like bi-modal mesopores using anionic surfactant as the template

Silica particles with lamellar and wormhole-like bi-modal mesopores have been synthesized using anionic surfactant (N-lauroylsarcosine sodium) as the template. The particles with diameters of 300―500 nm possess bi-modal mesopores with pore sizes of 3 nm and 12 nm, which were ascribed to the disordered wormhole-like mesophase and lamellar mesophase, respectively. The BET surface area of the particles was 536 m2/g and the pore volume was 0.83 cm3/g. The lamellar mesophase and cylindrical mesophase were formed...     

The success of dual‐functional templating for synthesizing hierarchical analcime zeolite

Novel and innovative hierarchical analcime zeolites were prepared by adding a gemini surfactant which acted as a dual‐functional template. Through a one‐step hydrothermal process, a hierarchical analcime zeolite with abundant intracrystalline mesopores was synthesized. Powder X‐ray diffraction and N₂ adsorption–desorption data show that the mesoporous composites possess both a quite a number of mesopores and analcime structure. The results suggest that the dual‐functional template can be effective in the synthesis of hierarchical analcime zeolites.     

Mesoporous amorphous MnO<Subscript>2</Subscript> as electrode material for supercapacitor

A kind of novel mesoporous, electrochemical active material, amorphous MnO₂ has been synthesized by an improved reduction reaction and using supramolecular as template. The synthesized sample was characterized physically by thermogravimetric analysis, X-ray diffraction, transmission electron microscope (TEM), and Brunauer–Emmett–Teller (BET) surface area measurement, respectively. Electrochemical characterization was performed using cyclic voltammetry and chronopotentiometry in 2 mol/l KOH aqueous solution electrolyte. The results of BET and TEM analysis indicated that supramolecular template plays an important role in the process of big specific surface area mesoporous material forming. After sintering at 200 °C, the sample still remained an amorphous structure, and its specific capacitance reached 298.7 F/g and presented a very stable capacitance after 500 cycles. In addition, the electrochemical process, such as ion transfer and electrical condition, was also investigated with electrochemical impedance spectroscopy.     

Synthesis and characterization of the air-water interfacial TiO2/ZrO2 binary oxide film

TiO(2)/ZrO(2) binary oxide film was self-assembled using anionic surfactant (sodium dodecyl sulfonate (SDS)) as template and obtained at the air-water interface. X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to characterize the obtained film. The film was composed of many lamellar nanorods with a d spacing of 3.2 nm, and the lamellas were perpendicular to the lengthwise position of the rods. The energy-dispersive spectrum (EDS) was used for determining the titanium/zirconium atomic ratio. After being calcined, the sample decomposed to a mixture of anatase titania and tetragonal zirconia, and all the lamellar structure was broken.