混合稀电解质条件下合成球状SBA-15粒子

在酸性合成法基础上, 不添加有机共溶剂和其它模板剂, 通过加入少量NH4F和Cu(NO3)2得到了分散的球状形貌SBA-15粒子. 对所得样品用小角X射线衍射(XRD)、N2吸脱附曲线、扫描电镜(SEM)进行表征, 讨论了不同电解质对样品形貌和孔结构的影响. 结果发现, 随着酸浓度增加, 得到了分散的规则六边形SBA-15粒子, 而加入一定量的氟化铵则得到了球形纠结状形貌的SBA-15. 实验表明, 氟离子在形成球状粒子的过程中起主要作用, 而Cu2+阻碍了球状粒子的纠结. 随着Cu2+浓度的增加, 部分硅源不能参与自组装生成SBA-15, 其原因可能是Cu2+与模板剂中亲水的聚氧乙烯形成PEO/Cu2+端基, 影响了硅源正常的缩聚.     

Temperature dependence of positron lifetime in ordered porous silica (SBA-3)

The temperature dependence of positron lifetime in uniform mesopores was analyzed. We used SBA-3 as the sample material, which possesses an ordered porous structure with uniform cylindrical mesopores. The positron lifetime corresponding to the annihilation in the mesopores increased gradually with a decrease in temperature down to 100 K, and its relative intensity also increased concomitantly. This result was attributed to the lower probability of the escape of the ortho-positronium (o-Ps) from the mesopores into the intergrain space at lower temperatures. An anomalous and sudden increase in the lifetime was observed at around 100 K; this result was in agreement with an increase in the positron lifetime reported in a previous study. It was revealed that the increase in the lifetime is very steep in cases of uniform mesopores, suggesting that the temperature dependence is influenced by the pore size.     

Preparation, Characterization and Catalytic Performance of La-SO42-/SBA-15 in Esterification of Acetic Acid with n-Butanol

La-SO42-/SBA-15 was synthesized with various amounts of lanthanum via incipient-wetness impregnation.Characterization was done by X-ray diffraction(XRD), transmission electron micrographs(TEM), nitrogen adsorption,FTIR spectroscopic analysis, thermogravimetric analysis, and the total amount of acidity of catalyst was estimated by TPD of NH3. The results indicate that lanthanum has been incorporated into SBA-15 molecular sieve. The prepared materials(La-SO42-/SBA-15) keep the highly ordered mesoporous two-dimensional hexagonal structure and do not change the mesoporous channel structure of the support SBA-15. The catalyst showed best catalytic activity in the synthesis of n-butyl acetate. The optimum conditions of the esterification by orthogonal experiments were studied: the molar ratio of n-butanol to acetic acid 1:1.2, the amount of catalyst 7.5%, reaction time 80 min. The yield of n-butyl acetate could reach 93.2% under the optimum conditions. The catalyst was recyclable, cost effective and environmental friendly.     

介孔材料SBA-15改性的复合凝胶聚合物电解质的制备及性能

以聚(甲基丙烯酸甲酯-聚乙二醇二甲基丙烯酸酯)(P(MMA-PEGDMA))共聚物为基体,介孔硅分子筛SBA-15为无机填料制备了复合凝胶聚合物电解质.采用原子力显微镜(AFM)、热重分析(TG)和交流阻抗(AC)等技术对其形貌、热稳定性及电化学性能进行了研究.结果表明:无机填料SBA-15与聚合物基体有较好的相容性;SBA-15的加入改善了聚合物电解质的热稳定性,提高了离子电导率,当W(SBA-15)=0.03时,离子电导率达最大值3.68×lO-3S/cm;并且掺杂SBA-15后,聚合物电解质的电化学稳定性得到了提高,其电化学稳定窗口为4.9V(vs Li /Li),可满足高性能锂离子电池的要求.     

催化苯羟基化反应的高效介孔VOx/SBA-16催化剂

利用浸渍法制备了介孔SBA-16负载高分散氧化钒催化剂(VOx/SBA-16),并使用XRD,TEM,N2物理吸附和Raman光谱对其进行了表征.结果表明,制备的VOx/SBA-16催化剂保持了SBA-16立方笼状孔结构,钒物种主要高度分散在SBA-16载体孔内.钒含量为7·3%的VOx/SBA-16催化剂在催化苯羟基化反应中表现出优异的催化性能.这是由于催化剂表面形成了高分散的VO4物种和纳米结构V2O5微晶.     

Low-Temperature Toluene Oxidation on Fe-Containing Modified SBA-15 Materials

Transition metals as catalysts for total VOC oxidation at low temperatures (150–280 °C) are a big challenge nowadays. Therefore, iron-modified SBA-15, AlSBA-15, and ZrSBA-15 materials with 0.5 to 5.0 wt.% Fe loading were prepared and tested for toluene oxidation. It was found that increasing Fe loading significantly improved the rate of oxidation and lowered the temperature of achieving 100% removal of toluene from above 500 °C for the supports (AlSBA-15 and ZrSBA-15) to below 400 °C for 5FeZrSBA-15. The formation of finely dispersed iron oxide active sites with a particle size less than 5 nm was observed on all the SBA-15, AlSBA-15, and ZrSBA-15 supports. It was found that the surface properties of the mesoporous support due to the addition of Al or Zr predetermined the type of formed iron oxide species and their localization on the support surface. Fe-containing SBA-15 and AlSBA-15 showed activity in total toluene oxidation at higher temperatures (280–450 °C). However, 5 wt. % Fe-containing ZrSBA-15 showed excellent activity in the total oxidation of toluene as a model VOC at lower temperatures (150–380 °C) due to the synergistic effect of Fe-Zr and the presence of accessible and stable Fe²⁺/Fe³⁺ active sites.     

温敏性介孔复合材料PNIPAAm/SBA-15的制备与表征

采用自由基引发原位聚合(in situ polymerization)的方法合成了温敏性聚N-异丙基丙烯酰胺(PNIPAAm)/介孔分子筛SBA-15纳米复合物. 用FT-IR、XRD、TEM、低温N₂吸附-脱附、TG和DSC等手段对复合物进行了表征, 结果表明, 单体N-异丙基丙烯酰胺(NIPAAm)在介孔孔内发生了原位聚合, 聚合物PNIPAAm比较均匀地附于孔壁, 含量达24%左右. 这一聚合和孔内填充没有破坏SBA-15的有序六方结构, 但使样品的表面积、孔径、孔容减小. 同时, 这一有机-无机纳米复合物仍然保持PNIPAAm的温度响应性, 最低临界溶解温度(LCST)与纯PNIPAAm相似.     

介孔SBA-15中有机模板剂的紫外/臭氧法脱除

紫外/臭氧法用于脱除有序介孔材料SBA-15中有机模板剂. 该方法是一种非加热光化学降解法, 简单、易操作, 可在温和条件下彻底除去SBA-15中三嵌段共聚物有机模板剂P123. 通过XRD, TEM, FT-IR和BET等对SBA-15经不同方法脱除模板剂前后的详细表征, 表明紫外/臭氧法在彻底脱除SBA-15中有机模板剂后, 保留了很好的骨架有序性, 比表面积更大, 孔道更加开放, 克服了高温焙烧脱除模板剂造成的孔道收缩.