三维贯穿大孔氧化铝的孔道改性、表征及转化机制

利用相分离技术制备了非晶三维贯穿大孔氧化铝初始材料,然后通过氨水水热改性处理,使其大孔形态发生了显著改变,孔壁边缘生长有尺寸为50-300 nm的片状聚集体,大孔尺寸由430 nm下降到250 nm,但仍然保持蠕虫状三维贯穿且空间分布均匀的特性。改性后的氧化铝材料经550℃焙烧转化为高结晶度γ氧化铝,比表面积达到331 m²/g,具有8.9 nm及250 nm两种集中的孔径分布,L酸度及抗压强度均有所提高。研究表明,无定形水合羟基铝离子聚合物与氨水发生再水合反应生成薄水铝石中间物,因此,可在较低的焙烧温度下转晶为γ态;大孔孔壁边缘的AlOOH晶粒受NH₄⁺模板诱导作用从里向外重排形成片状聚集体,从而改变了大孔的形态。     

介孔氧化铝的溶胶-凝胶法制备

以硝酸铝为铝源,十六烷基三甲基溴化铵和尿素为复合模板剂,采用溶胶-凝胶法制备了介孔氧化铝（1）,其结构经TEM, XRD, TG-DTA和N₂-BET表征。结果表明：1比表面积较大（＞400 m²·g^-1）,孔径分布窄(3～5 nm),形成的蠕虫状孔道具有短程有序性。     

有序多级孔N/Nd/TiO_2的制备及其在可见光下催化降解甲基橙的性能

以聚苯乙烯为胶晶模板,采用溶胶-凝胶法制备了有序多级孔N/Nd/TiO_2(1),其结构和形貌经SEM,XRD,XPS和N2吸附-脱附表征。研究了1在可见光下催化降解甲基橙的性能。结果表明:1为有序大孔/介孔多级结构,大孔孔道/介孔孔窗呈相互通透三维有序结构,大孔孔道内径约230 nm,介孔孔窗约30 nm,比表面积为125.50 m~2·g~(-1),比孔容为1.124 5 cm~3·g~(-1)。1催化甲基橙的脱色率为42.76%。     

介孔/大孔 Al2O3-SiO2复合氧化物的制备与表征

 以正硅酸甲酯和硝酸铝为硅和铝的前驱体,以非离子表面活性剂C16EO10为结构导向剂,采用溶胶-凝胶法制备了双孔结构硅铝复合氧化物材料. 扫描电镜和N2吸附/脱附分析表明,材料具有三维连续大孔和骨架介孔的双孔分布结构. 微米范围的连续大孔结构是由于溶胶-凝胶过程中诱发了Spinodal相分离所致,而骨架介孔的形成则可能是由于表面活性剂分子进入凝胶骨架中,起到构建介孔结构的模板作用. 骨架元素分析结果表明,制备过程中添加的铝大部分进入了凝胶骨架中,取代部分硅而形成酸性硅铝复合氧化物. 采用Hammett指示剂法和吡啶吸附红外光谱法分析了材料的表面固体酸性,结果显示,硅铝复合氧化物属于中强酸,酸强度H0在-5.6～-3.0 之间的酸中心数约为0.35 mmol/g, 并且材料表面的L酸位较为丰富, B酸位相对较少.     

贯通孔道网络结构大孔Al2O3催化材料的制备

采用模板法制备了具有贯通孔道网络结构的大孔Al2O3催化材料. 为确保模板材料的体积分数低于74%时Al2O3孔道的贯通, 设计并实现了模板聚苯乙烯(PS)微球先胶凝再与催化材料Al2O3纳米颗粒复合的制备路线. 通过PS微球悬浮液的流变性表征凝胶状态的形成. 实验结果表明, 加入适当浓度的硝酸铝溶液后PS微球悬浮液出现了由溶胶向凝胶的转变. 通过扫描电镜对大孔Al2O3催化材料的孔道结构进行表征, 结果表明, 与有序大孔材料相比大孔催化材料中孔配位数有所降低, 骨架厚度提高且具有贯通的孔道网络结构. 大孔结构抗压强度实验表明, 随着模板PS微球质量分数的降低, 机械强度明显提高.     

多级复合孔硅铝材料的合成与表征

采用表面包覆聚电解质的聚苯乙烯小球为模板,制备多级复合孔硅铝材料前体。 经水热晶化处理后焙烧脱模板,获得了多级孔结构的硅铝分子筛材料。 通过X射线衍射、傅里叶红外光谱、N2吸附-脱附、扫描电子显微镜和透射电子显微镜等测试技术对水热晶化不同时间的硅铝材料进行表征。 探讨了水热晶化时间对材料孔道结构的影响。 结果表明,水热晶化时间小于22 h,样品中含有介孔-大孔双连续孔道体系。 晶化时间超过22 h,样品中含有微孔-介孔-大孔多级孔道体系。 晶化36 h的样品,大孔孔壁由纳米级ZSM-5型沸石分子筛晶体构成。     

高比表面积有序介孔氧化铝的制备与表征

采用溶胶-凝胶法以非离子表面活性剂PEO-PPO-PEO三嵌段共聚物F127为模板剂, 以异丙醇铝为铝源, 以异丙醇为溶剂, 成功地制备出比表面积为485 m2/g、孔径分布窄(2~20 nm)、孔容在1.2 cm3/g以上和孔道呈蠕虫状且具有一定有序性的介孔氧化铝. 采用BET, TEM, XRD和TG多种测试技术对产物性能进行了表征. 探讨了水铝比、醇水混合溶液的滴加速度、反应时间、水浴温度、陈化温度及陈化时间等条件对合成的有序介孔氧化铝结构的影响.     

溶胶凝胶法制备中孔分布集中的氧化铝催化材料

报道一种新的中孔氧化铝催化材料的制备方法.通过该方法可以以无机盐和SB粉为原料经过沉淀、解胶的过程首先制得稳定的铝溶胶,然后经过干燥、焙烧得到中孔氧化铝催化材料.用BET,TEM,DTA和XRD等方法对该中孔氧化铝催化材料的基本物理化学性质进行了表征.实验结果表明在不使用模板剂的前提下,通过本文报道的方法能够制得比表面积较大、中孔分布集中的氧化铝材料,并且其孔径分布主要集中在4nm左右.实验结果表明以SB粉为原料制备得到的氧化铝材料具有较好的热稳定性.     

SiO2阶层多孔结构搭建及块体材料制备机理

借助溶胶-凝胶结合相分离和模板法进行了阶层多孔结构的搭建及二氧化硅多孔块体材料的制备,表征了阶层多孔块体的显微结构及孔结构特性,分析了阶层多孔结构的搭建机理。研究结果表明,三嵌段共聚物聚环氧乙烷-聚环氧丙烷-聚环氧乙烷（P123）的加入不仅诱导共混体系发生相分离,调控大孔结构的形成,同时形成球形胶束并作为模板剂进入骨架,而1,3,5-三甲基苯（TMB）的加入使P123形成的胶束膨胀且更加稳定,在骨架上成功引入了球形介孔,骨架中凝胶粒子相互聚集形成微孔,从而搭建贯通大孔-球形介孔-微孔同时分布的阶层多孔结构,并获得相应的多孔块体材料;当正硅酸甲酯（TMOS）：P123：TMB摩尔比为1：0.015：0.353时,多孔块体材料的阶层多孔结构最优,大孔孔径为0.5-1.5 μm,介孔孔径为3-4 nm,显气孔率66.1%,比表面积为616 m²·g^-1。     

以天然植物为模板合成高度有序的多级复合孔材料

筛选出两种孔径较大且孔结构规则的植物为大孔模板, 以嵌段共聚物为介孔相模板成功合成了两种具有连续的骨架和贯通的大孔孔道(大孔孔径大于40 μm, 其孔壁为介孔相)的高度有序多级复合孔材料. 对该复合孔材料进行了水热稳定性研究. 用扫描电子显微镜(SEM)、粉末X射线衍射仪(XRD)、高分辨率透射电镜(HRTEM)以及N₂吸附-脱附等测试手段对合成的样品进行了表征. 结果表明, 合成的产物是孔道相互贯通的多级有序复合孔硅材料, 具有较好的水热稳定性. 采用此合成方法可精确地复制大孔植物模板.     

CaF2-Al2O3-MgO电渣微结构的原位拉曼光谱及27Al魔角旋转核磁共振研究

运用原位拉曼光谱和 ²⁷Al魔角旋转核磁共振研究了CaF₂-Al₂O₃-MgO电渣重熔渣晶体、 玻璃和熔体的微结构及铝配位数的变化. 利用X射线粉末衍射分析获得该晶体样品中存在的物相, 分别基于密度泛函理论及量子化学从头算分析了S-6530晶体和熔体中相关物相的拉曼振动波数及散射活性, 并对其主要振动模式进行了归属. 结果表明, S-6530晶体中铝主要以六配位形式存在, 并有少量的四、 五配位. 在升温过程中, 其中MgAl₂O₄物相的Al-O多面体由[AlO₆]转变成[AlO₄]与[AlO₅]共存. Al在熔体和玻璃结构中主要以[AlO₄]四面体的形式存在, 其占比高达71.1%, 相较于其晶态, [AlO₅]的占比也增加至28.6%. 基于构建的熔体团簇模型的量子化学从头算表明, [AlO₄]构型倾向于以Q₃, Q₄连接方式为主的层状和架状结构, 而[AlO₅]构型则倾向于单体形式.     

植物固体纤维丝在NiMo柴油加氢脱硫催化剂中的应用

通过在氧化铝载体加入微米级植物固体纤维丝扩孔，制备出NiMo柴油加氢脱硫催化剂。采用BET、XRD、SEM、Raman与TEM对制备的载体及催化剂进行表征研究。结果表明，植物固体纤维丝能够在催化剂中构建出部分直筒大孔，NiMo活性组分在催化剂载体上实现了高度分散，活性相MoS₂堆叠层数集中在3-5层，平均MoS₂条长度为4.49 nm。研究了催化剂载体中植物固体纤维丝含量对催化剂活性的影响，并与常规氧化铝载体催化剂进行了对比，高压微反评价结果表明，开发的含有3%（质量分数）植物固体纤维丝NiMo柴油加氢脱硫催化剂比常规NiMo催化剂活性更高，其加氢脱硫活性提高了5%-15%。     

Nondestructive technique for the characterization of the pore size distribution of soft porous constructs for tissue engineering

Polymer scaffolds tailored for tissue engineering applications possessing the desired pore structure require reproducible fabrication techniques. Nondestructive, quantitative methods for pore characterization are required to determine the pore size and its distribution. In this study, a promising alternative to traditional pore size characterization techniques is presented. We introduce a quantitative, nondestructive and inexpensive method to determine the pore size distribution of large soft porous solids based on the on the displacement of a liquid, that spreads without limits though a porous medium, by nitrogen. The capillary pressure is measured and related to the pore sizes as well as the pore size distribution of the narrowest bottlenecks of the largest interconnected pores in a porous medium. The measured pore diameters correspond to the narrowest bottleneck of the largest pores connecting the bottom with the top surface of a given porous solid. The applicability and reproducibility of the breakthrough technique is demonstrated on two polyurethane foams, manufactured using the thermally induced phase separation (TIPS) process, with almost identical overall porosity (60-70%) but very different pore morphology. By selecting different quenching temperatures to induce polymer phase separation, the pore structure could be regulated while maintaining the overall porosity. Depending on the quenching temperature, the foams exhibited either longitudinally oriented tubular macropores interconnected with micropores or independent macropores connected to adjacent pores via openings in the pore walls. The pore size and its distribution obtained by the breakthrough test were in excellent agreement to conventional characterization techniques, such as scanning electron microscopy combined with image analysis, BET technique, and mercury intrusion porosimetry. This technique is suitable for the characterization of the micro- and macropore structure of soft porous solids intended for tissue engineering applications. The method is sensitive for the smallest bottlenecks of the largest continuous pores throughout the scaffold that contributes to fluid flow.     

富氮多级孔炭材料的制备及其吸附分离CO2的性能

使用新型含氮聚合物席夫碱为炭源, SBA-15为模板,通过纳米铸型法原位合成微孔-中孔-大孔串联的多级孔富氮炭材料.材料的比表面积为752 m²·g^-1,孔容0.79 cm³·g^-1; X光电子能谱分析表明炭材料中的氮含量高达7.85%(w).将所制备的多孔炭材料应用于CO₂的吸附分离,发现炭材料的微孔发挥主导作用,表面氮掺杂发挥辅助作用.在两者的协同作用下, CO₂吸附量在常压、273 K下可达97 cm³·g^-1, CO₂/N₂和CO₂/CH₄的分离比(摩尔比)分别为7.0和3.2,低压亨利吸附选择性分别为23.3和4.2.采用Toth模型对单组分平衡吸附进行拟合,并根据理想溶液吸附理论(IAST)预测双组分CO₂/N₂和CO₂/CH₄混合气体的分离选择性分别为40和18.     

Microporous Zinc Formate for Efficient Separation of Acetylene over Carbon Dioxide

Separation of acetylene(C₂H₂) from carbon dioxide(CO₂) by adsorbents is very challenging owing to their high similarity on molecular shape and dimension. Exploring inexpensive and easily available porous materials is of importance to facilitate the practical implementation of the challenging but energy-efficient separation. Herein, we utilize an easily available porous material[Zn₃(HCOO)₆] for the selective separation of C₂H₂ over CO₂. Because of the pore confinement in[Zn₃(HCOO)₆](pore size of 0.47 nm) and accessible oxygen sites for preferential binding of C₂H₂, this material exhibits high low-pressure uptake for C₂H₂(63 cm³/cm³ at 10 kPa and 298 K) and high C₂H₂/CO₂ selectivity(7.4 under ambient conditions) that is comparable to those of out-performing porous materials. The efficient separation of[Zn₃(HCOO)₆] for C₂H₂/CO₂ mixture has also been confirmed by the breakthrough experiments.     

Easily Separated and Recyclable Amino-functionalized PorousSiO2 Beads with 3D Continuous Meso/Macropore Channels

Amino-functionalized porous SiO₂ beads with a diameter of 200—800 μm(PSB-NH₂) have been successfully synthesized by grafting 3-aminopropyl-triethoxysilane onto meso/macroporous silica beads(PSB), in which the PSB was prepared by hydrothermal synthetic method with a porous hard template anion-exchange resin. The as-prepared materials were characterized by means of nitrogen sorption and transmission electron micrographs(TEM), showing the presence of 3D interconnected and continuous large mesopores and macropores inside. The beads were used to catalyze Knoevenagel condensation and proved to be highly active and selective due to the high accessibility of the reactants to the amino groups via the continuous 3D meso/macopores. Notably, such material in bead format facilitates the extremely straightforward separation from reaction solution without any centrifugation or filtration. Moreover, PSB-NH₂ proved to be a stable catalyst via leaching experiment test, and can be easily recovered and reused without significant loss of activity in successive catalytic cycles.     

Preparation of YSZ Microporous Membranes on Porous a-Alumina with Metal Chlorides as Precursor

A sol-gel process for YSZ membrane prepared with less expensive chemicals, ZrOCI₂·8H₂0 and YC1₃, has been developed. The sol viscosity as a function of concentration, acidity and temperature was brane formation processes were also studied. investigated. And gelation and Based on an optimized procedure memhole and crack-free YSZ membranes with the pore size less than 100 nm have obtained on coarse porous a-alumina.     

Synthesis and characterization of MCM-48 tubular membranes

MCM-48 membranes have been prepared on alumina supports of different pore sizes. A battery of characterization techniques has been used to study the physical properties and the quality of the membranes prepared. The highest quality membranes were prepared on supports with pore size of up to 60 nm. The MCM-48 membranes were tested in the separation of gas phase mixtures and a cyclohexane/O₂ selectivity higher than 270 was obtained. The selective separation of organic compounds from inert components is a result of the cooperative effects of capillary condensation in MCM-48 pores and of the specific interactions of the permeating compounds and the membrane material.