反相微乳液法制备纳米氧化铝

采用由环己烷、聚乙二醇辛基苯基醚(TritonX-100)、正丁醇与水溶液构成的反相微乳液体系, 合成了纳米Al2O3粉体. 采用X射线衍射、扫描电子显微镜、透射电子显微镜、比表面积分析仪等表征手段, 分别对产物的结构、形貌、比表面积和孔容进行了表征, 该纳米Al2O3比表面积约450 m2·g-1(随反应参数不同发生变化), 均属γ-Al2O3, 粒径均匀, 颗粒直径小于10 nm. 考察了微乳液体系中水与表面活性剂的物质的量之比r0、表面活性剂与助表面活性剂的体积比φ、焙烧温度等关键因素对产物比表面积等物理性质的影响. 结果表明, 当r0=20, φ=0.5, 焙烧温度为500 ℃时, 可以得到大比表面积、高孔容、分散性好及粒径分布均匀的γ-Al2O3粉体.     

制备方法对负载型纳米ZrO2/Al2O3复合载体性能的影响

采用浸渍-沉淀法制备了负载型纳米ZrO2/Al2O3复合载体.采用X射线衍射、N2物理吸附、差示扫描量热(DSC)和程序升温脱附等技术考察了浸渍方式和干燥方法对复合载体的表面性能、热稳定性和晶相结构的影响.结果表明,ZrO2/Al2O3复合载体中没有生成ZrO2-Al2O3复合氧化物或固溶体,纳米ZrO2仅负载在Al2O3的表面.微波干燥法制备的ZrO2/Al2O3复合载体的比表面积(158.7 m2/g)较大,最可几孔径为19.4 nm,ZrO2的粒度为4.2 nm,晶相结构为四方相ZrO2.微波诱导作用使ZrO2/Al2O3复合载体表面产生了新的酸碱中心,微波干燥法制备的ZrO2/Al2O3复合载体具有较强的热稳定性,在873~1 073 K范围内DSC曲线没有出现吸热峰,而其它干燥方法制备的复合载体在903~1 023 K范围内出现了较明显的吸热峰,表明复合载体表面的部分四方相ZrO2转变为单斜相ZrO2(m-ZrO2).对超声波处理过的复合载体进行微波干燥能进一步提高纳米ZrO2与Al2O3之间的相互作用,纳米粒子的粒度(3.4 nm)更小,分布更均匀,但没有改变ZrO2的晶相结构.     

负载型纳米ZrO_2/Al_2O_3复合载体的制备和表征及其Ni/ZrO_2/Al_2O_3催化性能的研究

以大孔Al2O3为基载体,采用沉积-沉淀法和溶胶-沉积法制备了负载型纳米ZrO2/Al2O3复合载体.用XRD、TEM和比表面与孔径测定等手段对载体进行了表征.结果表明,负载型纳米ZrO2/Al2O3复合载体具有较大的比表面积和适宜的孔径分布,纳米ZrO2在载体上呈单层均匀分布.以CH4-CO2重整制合成气为探针反应,考察了Ni/ZrO2/Al2O3催化剂的活性和选择性.     

负载型纳米TiO2／Al2O3复合载体负载SO4^2-催化剂的制备与催化性能研究

分别采用沉淀法,水解法和溶胶凝胶法制备了负载型纳米TiO2/Al2O3复合载体,同时在复合载体表面负载SO42-制成SO42-/TiO2/Al2O3固体酸催化剂,并将此催化剂用于α-蒎烯异构化反应中.用XRD、FTIR,TPD等手段对催化剂的晶相结构、比表面积、孔径分布、表面酸性等进行了表征.结果表明,三种方法所制备的催化剂均为纳米级且拥有着丰富而规则的孔结构,水解法制备的SO42-/TiO2/Al2O3催化剂中TiO2的平均粒径(10.0 nm)较小,比表面积(172.88 m2/g)较大,平均孔径为3.926 nm,表面酸中心数和酸强度均高于沉淀法和溶胶凝胶法制备的催化剂,在α-蒎烯催化异化反应中的具有较高的活性,α-蒎烯转化率为82.76%.     

聚合氯化铝制备球形拟薄水铝石和γ-Al_2O_3的研究Ⅰ——制备条件探讨

采用实验室自制的聚合氯化铝为原料,结合溶胶-凝胶法和油滴法制备球形拟薄水铝石及其衍生物γ-Al2O3,采用XRD,TEM和N2吸附法对样品进行了分析表征,探讨了不同pH值、不同铝形态含量的聚合氯化铝、不同煅烧温度及不同表面活性剂对产物结构性质的影响。结果表明:pH值在8.5附近合成的水合氧化铝以拟薄水铝石为主;高Alc含量的聚合氯化铝有利于形成高比表面积的球形产物;在450～750℃下煅烧产物为球形γ-Al2O3,并且随温度升高,产物比表面积下降、孔径增大,孔容变化不明显,在1000℃下煅烧产物为球形θ-Al2O3与γ-Al2O3的混合物;随着聚乙二醇表面活性剂分子量的增加,所得球形γ-Al2O3的孔容和孔径增大,聚乙二醇10000的扩孔效果最好,450℃下煅烧所得球形γ-Al2O3的比表面积、孔容分别达326m2·g-1、0.55cm3·g-1。     

负载型纳米ZrO2/Al2O3复合载体的制备和表征及其Ni/ZrO2/Al2O3催化性能的研究

以大孔Al2O3为基载体，采用沉积-沉淀法和溶胶-沉积法制备了负载型纳米ZrO2/Al2O3复合载体．用XRD、TEM和比表面与孔径测定等手段对载体进行了表征．结果表明，负载型纳米ZrO2/Al2O3复合载体具有较大的比表面积和适宜的孔径分布，纳米ZrO2在载体上呈单层均匀分布．以CH4-CO2重整制合成气为探针反应，考察了Ni/ZrO2/Al2O3催化剂的活性和选择性．     

Ba、Mn对Al2O3热稳定性和甲烷催化燃烧活性的影响

采用溶胶-凝胶法制备BaO•6Al2O3系列催化剂.考察了Ba、Mn的引入对Al2O3的热稳定性及甲烷催化燃烧性能的影响.结果表明, Ba在高温下与Al2O3首先生成BaAl2O4，然后进一步与Al2O3反应生成具有β-Al2O3结构的BaAl12O19六铝酸盐，抑制了Al2O3进一步的烧结，提高了催化剂的热稳定性. Mn的引入也能够促进六铝酸盐的生成并提高催化剂的甲烷燃烧活性.采用超临界干燥法可抑制干燥过程中因毛细收缩引起的比表面积降低.所制备的BaMnAl11O19催化剂经1200 ℃焙烧4 h后，比表面积为35.1 m2•g－1，在空速40000 h－1条件下，10％甲烷转化温度(T10％)为500 ℃，催化活性明显高于常规干燥法制备的相应催化剂.     

Pd/Al2O3膜的制备及其对 1,5-环辛二烯加氢的催化性能

利用微乳液浸渍技术制备了负载型Pd/Al2O3膜,并用扫描电镜和原子吸收光谱对微乳液中的纳米Pd颗粒及其在Al2O3陶瓷膜载体上的形貌、分布和负载量进行了表征.在"催化接触器"型膜反应器中,以1,5-环辛二烯(COD)加氢作为模型反应考察了Pd/Al2O3膜的催化性能.结果表明,采用微乳液技术制备Pd/Al2O3膜时,Pd负载量、浸渍操作方式、焙烧温度和载体孔径对Pd/Al2O3膜的催化性能有一定影响.要获得对COD加氢反应的高催化活性和较高的中间产物环辛烯选择性,优化的Pd/Al2O3膜制备条件为:缓慢析出Pd纳米颗粒,同时采用循环浸渍方式,焙烧温度300℃,膜载体孔径1.9μm.     

纳米ZrO2/Al2O3复合载体及Ni/ZrO2/Al2O3催化剂的性能研究

 采用溶胶-凝胶法在经过扩孔处理的Al2O3基载体上制备了纳米ZrO2/Al2O3复合载体,并通过浸渍法制备了NiO/ZrO2/Al2O3催化剂. 用XRD,TPR,TPD和N2吸附等技术分别考察了载体和催化剂的结构及表面性能,研究了复合载体对Ni/ZrO2/Al2O3催化CO2重整CH4反应性能的影响. 结果表明,纳米ZrO2/Al2O3复合载体具有较大的比表面积、适宜的孔径分布及稳定的t-ZrO2结构,Ni/ZrO2/Al2O3催化剂具有较好的CO2重整CH4反应活性和稳定性.     

稀土氧化物掺杂对SO4^2-／ZrO2／Al2O3催化剂催化性能的影响

采用浸溃-沉淀法在具有较大比表面积的Al2O3上直接合成纳米ZrO2制备负载型纳米ZrO2/Al2O3复合载体,并将氧化钪、氧化钕、氧化错等稀土氧化物(RExOy)分别掺杂到负载型纳米ZrO2/Al2O3复合载体中以改善ZrO2的表面性能.同时以此复合载体负载SO42-制备SO42-/RExOy-ZrO2/Al2O3催化剂.运用XRD,BET,NH3-TPD,原位红外等技术与方法对催化剂的晶相结构、比表面积、孔径分布、酸中心种类等进行表征,并以α-蒎烯异构化反应为探针考察了催化剂的催化性能.结果表明,掺杂的稀土氧化物没有改变ZrO2的晶相结构,但ZrO2粒度有所减小,催化剂的比表面积增加,同时稀土氧化物的存在还会改变催化剂表面SO42-的配位方式,提高表面酸中心数和酸强度,增强催化剂的活性.催化剂的孔结构对选择性有较大的影响.     

Application of tetrahydrofuran dispersant in microemulsion for fabricating titania mesoporous thin film

A new strategy was used to fabricate titania mesoporous thin film by incorporating tetrahydrofuran (THF) into the CTAB/n-butyl alcohol/cyclohexane/water reverse microemulsion as a micelle disperser. Highly dispersed and congregated TiO(2) particles in the microemulsion with and without THF were observed by transmission electron microscopy (TEM), respectively. The photographs observed by field-emission scanning electron microscopy (FE-SEM) show that a uniform titania mesoporous thin film with monodisperse TiO(2) spherical nanoparticles of ca. 20 nm was obtained using the microemulsion with THF.     

微乳液聚合耦合共混法构建聚偏氟乙烯共混杂化膜

以苯乙烯和甲基丙烯酸甲酯混合物作为油相, 采用反相微乳液法制备了AgCl纳米粒子; 通过微乳液原位聚合油相单体得到包含AgCl纳米粒子的聚合乳液; 将聚合乳液与聚偏氟乙烯(PVDF)通过共混法构建了包含AgCl纳米粒子的PVDF共混杂化膜. 紫外-可见光谱、 透射电子显微镜(TEM)及扫描电子显微镜(SEM)等表征结果和超滤实验结果表明, 聚合乳液加入的同时引入了亲水性聚合物和表面亲水的AgCl纳米粒子, 不仅改善了PVDF共混杂化膜的孔隙率和平均孔径, 还显著增强了PVDF共混杂化膜的极性和亲水性, 最终提升了膜的水通量和抗污染性能; 过量聚合乳液加入后不能与PVDF材料均匀共混, 而且AgCl纳米粒子也会在膜中形成团聚物堵塞膜孔隙, 从而削弱了膜的水通量和抗污染性能.     

Size-controlled synthesis of SnO2 nanoparticles using reverse microemulsion method

Tin oxide nanoparticles were prepared using an ionic surfactant (sodium dodecyl sulfate) and tin (IV) chloride as an inorganic precursor via the reverse microemulsion method. The size of the nanoparticles is controlled by variation of water-to-surfactant ratio. Eliminating of surfactant in prepared nanoparticles was confirmed by the infrared spectroscopy after sequential calcinations. Transmission electron microscopy, surface area, pore volume, average pore diameter, pore size distribution and X-ray diffraction results were used for evaluation of size distribution, shape and structure of prepared SnO₂ nanoparticles. Transmission electron micrographs confirmed that the obtained materials are spherical nanoparticles. The X-ray diffraction results show the crystalline phases of all samples are SnO₂ with tetragonal structured crystal. In addition, the X-ray diffraction and transmission electron microscopy data showed that the size of SnO₂ nanoparticles decreased with decreasing the water-to-surfactant ratio.     

反相微乳液法制备膜状普鲁士蓝类配合物纳米材料

在十六烷基三甲基溴化铵(CTAB)/正戊醇/异辛烷/水构成的油包水型(W/O)微乳体系中合成了膜状及50 nm立方状的Co-Fe普鲁士蓝类配合物(cobalt-iron Prussian blue analogues). 研究了w值(水与CTAB的物质的量的比)、反应物浓度和反应温度对产品形貌的影响. 并用原子力显微镜(AFM), 透射电子显微镜(TEM), 电子能谱(EDS), X射线光电子能谱(XPS)和红外(IR)对产品进行了表征.     

Magnesium hydroxide nanoparticles synthesized in water-in-oil microemulsions

Well-dispersed magnesium hydroxide nanoplatelets were synthesized by a simple water-in-oil (w/o) microemulsion process, blowing gaseous ammonia (NH(3)) into microemulsion zones solubilized by magnesium chloride solution (MgCl(2)). Typical quaternary microemulsions of Triton X-100/cyclohexane/n-hexanol/water were used as space-confining microreactors for the nucleation, growth, and crystallization of magnesium hydroxide nanoparticles. The obtained magnesium hydroxide was characterized by field-emission scanning electron microscopy (FESEM), high-resolution transmission election microscopy (HRTEM), X-ray powder diffraction (XRD), laser light scattering, Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis-differential scanning calorimetry (TGA-DSC). The mole ratio of water to surfactant (omega(0)) played an important role in the sizes of micelles and nanoparticles, increasing with the increase of omega(0). The compatibility and dispersibility of nanoparticles obtained from reverse micelles were improved in the organic phase.     

氨基化单分散量子点/二氧化硅核壳纳米粒子的制备及其细胞标记

通过反向微乳液法, 在油溶性量子点表面包裹二氧化硅外壳, 使油溶性量子点水溶性化, 再利用3-氨丙基三乙氧基硅烷(APTES)在已形成的二氧化硅纳米颗粒表面进行氨基化改性, 制备富含氨基的二氧化硅包裹的量子点荧光纳米球. 通过透射电子显微镜(TEM)、粒径分析、zeta电位检测、紫外-可见分光光度、荧光分光光度和红外光谱等手段对产品进行了表征. 结果表明, 所制备的二氧化硅量子点纳米球(45 nm)具有单分散性、水溶性好及光化学稳定性强等优点. 通过静电作用, 所制备的单分散氨基化二氧化硅量子点对肿瘤细胞表面膜电荷进行了初步标记显像.     

电极/反相微乳液体系电沉积制备纳米金镀层

将含有氯化金的强酸性水溶液作为水相与Triton X-100、正己醇、正己烷组成反相微乳液体系, 并以该微乳液构成电极/反相微乳液电极系统, 利用电沉积方法成功地制备出纳米Au镀层. 循环伏安和交流阻抗对反相微乳液体系电沉积过程的研究发现, 微乳液中Au(III)的还原为完全不可逆过程, 其电化学反应的阻抗值约为具有相同表观浓度氯化金水溶液体系的5.5倍. SEM研究结果表明, 利用微乳液体系电沉积获得的金镀层由纳米Au颗粒组成, 直径为50 nm左右. 所制备的纳米Au修饰电极由于具有较大的比表面积, 其电化学性能优于纯Au电极, 该电极在酸性条件下有较好的析氢性能, 在碱性条件对丙三醇有较好的电催化氧化性能.     

Silica encapsulation of hydrophobically ligated PbSe nanocrystals

Spherical PbSe@SiO2 nanoparticles have been successfully synthesized within reverse micelles via metal alkoxide hydrolysis and condensation within a microemulsion system. These core-shell nanoparticles were characterized by transmission electron microscopy (TEM), NIR absorption spectroscopy, energy-dispersive X-ray analysis, and TEM electron diffractions. It shows that the obtained core-shell structures have a spherical shape with narrow size distribution (average size approximately 35 nm) and smooth surfaces. The size of the particles and the thickness of the shells can be controlled by manipulating the relative rates of the hydrolysis and condensation reactions of tetraethoxysilane (TEOS) within the microemulsion.     

Microemulsion Synthesis of Nanosized TiO2 Particles Doping with Rare-Earth and their Photocatalytic Activity

Microemulsion is the easiest and cleanest of the popular methods of synthesizing nanomaterial. This work synthesized the nanosized La-TiO₂ and Ce-TiO₂ particles through the hydrolyzation of tetrabutyl titanate in a Triton X-100/n-hexanol/cyclohexane/water reverse microemulsion. The particles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform-infrared spectroscopy (FT-IR) and thermogravimetry (TG). The photocatalytic activity was evaluated by photocatalytic degradation of methyl orange (MO) under ultraviolet light and visible light irradiation. The results showed that reverse microemulsion produced the nanosized and well-separated particles, which are obviously in degrading MO. Comparing the pure TiO₂ with doping TiO₂, the doping ones are smaller and have better photocatalytic activity, which was best at the molar content of 0.1% for La, whereas for Ce it was 0.5%.