三氟丙基修饰的有机-无机杂化二氧化硅膜制备、氢气分离及水热稳定性能

以三氟丙基三甲氧基硅烷(TFPTMS)和1,2-双(三乙氧基硅基)乙烷(BTESE)为前驱体, 通过溶胶-凝胶法在酸性条件下制备三氟丙基修饰的有机-无机杂化SiO₂膜材料, 并深入研究三氟丙基修饰对溶胶粒径和疏水性能的影响以及膜材料的氢气渗透分离性能和长期水热稳定性. 结果表明三氟丙基已成功修饰到有机-无机杂化SiO₂膜材料中, 且随着TFPTMS修饰量的增加, 溶胶粒径有减小趋势, 膜材料的疏水性能逐渐提高. 当n(TFPTMS)/n(BTESE)＝0.6时, 溶胶平均粒径为2.11 nm, 膜材料对水的接触角达到111.6°±0.7°. H₂在修饰后膜材料中的输运主要遵循微孔扩散机理, 300 ℃时H₂的渗透率为8.86×10^-7 mol·m^-2·s^-1·Pa^-1, H₂/CO₂的理想分离系数达到5.4, 且当进气摩尔比例为1∶1时H₂/CO₂的双组分气体分离系数达到了4.82, 均高于Knudsen扩散分离因子(H₂/CO₂＝4.69), 膜材料呈现出良好的分子筛分性能. 膜材料在250 ℃及水蒸气摩尔含量为5%的水热环境中能稳定工作300 h以上.     

十三氟辛基修饰的疏水有机-无机杂化二氧化硅膜孔结构、氢气分离及水热稳定性

采用1,2-双(三乙氧基硅基)乙烷(BTESE)和十三氟辛基三乙氧基硅烷(PFOTES)为前驱体,在酸性条件下通过溶胶-凝胶法制备了十三氟辛基修饰的有机-无机杂化SiO2膜材料。利用接触角测量、红外光谱、动态光散射和N2吸附等测试技术分别对膜材料的疏水性、溶胶粒径和孔结构进行表征,并深入研究有支撑膜材料的氢气渗透、分离性能以及长期水热稳定性。结果表明,十三氟辛基修饰后的膜材料由亲水性变成了疏水性,当nPFOTES/nBTESE=0.6时膜材料对水的接触角达到(110.4±0.4)°,膜材料还保持微孔结构,孔径分布在0.5~0.8 nm。氢气在修饰后的膜材料中的输运遵循微孔扩散机理,在300℃时,氢气的渗透率达到8.5×10-7mol·m-2·s-1·Pa-1,H2/CO2,H2/CO和H2/SF6的理想分离系数分别为5.49,5.90和18.36,均高于相应的Knudsen扩散分离因子。在250℃且水蒸气物质的量分数为5%水热环境下陈化250 h,氢气渗透率和H2/CO2的理想分离系数基本保持不变,膜材料具有良好的水热稳定性。     

表面修饰的有机-无机杂化微孔SiO2膜的制备及氢气分离性能

采用苯基三乙氧基硅烷(PTES)和1,2-双(三乙氧基硅基)乙烷(BTESE)为前驱体, 通过溶胶-凝胶法制备了苯基修饰的有机-无机杂化SiO2 膜材料. 通过N2吸附、视频光学接触角测量、热重分析和红外光谱对膜材料的孔结构和疏水性能进行了表征, 并深入研究了膜材料的氢气渗透和分离性能. 结果表明, 修饰后的膜材料具有微孔结构, 孔径集中分布在0.4~0.6 nm. 在温度为40 ℃, 湿度为70%~80%的水热环境下陈化30 d后, 膜材料仍保持微孔结构. 苯基修饰后膜材料具有疏水性, 当n(PTES)/n(BTESE)=0.6时, 膜材料对水的接触角达到(125±0.4)°. 氢气在膜材料中的输运遵循活化扩散机理, 300 ℃时, 膜材料的H2渗透率达到8.71×10-7mol·m-2·Pa-1·s-1, H2/CO2的理想分离系数达到5.53.     

溶胶-凝胶法制备硅系有机-无机杂化分离膜

以α-Al₂O₃多孔陶瓷片为载体,用溶胶-凝胶法制备有机-无机杂化分离膜.通过考察前驱物的组成及杂化溶胶的合成条件对制膜工艺过程的影响,得到了制备有机-无机杂化分离膜的各种适宜性参数.红外光谱(FTIR)分析结果表明,杂化溶胶的性能不仅决定分离膜的性能,而且对膜热处理过程中的龟裂有很大影响.膜层的厚度为1～2μm;在膜两侧压差为0.10MPa、n(PTMOS)/n(TEOS)=1.16时,膜对O₂/N₂,CO₂/N₂和CO₂/O₂的分离因子分别为2.30,4.31和1.17,渗透系数为75.81×10^-17,75.28×10^-17和72.78×10^-17m₃(STP)·m/(m₂·s·Pa).     

溶胶-凝胶法制备聚醚砜-二氧化硅复合材料

以聚醚砜(PES)为基体,通过溶胶-凝胶过程,得到了分散均匀的PES/SiO₂杂化材料,用扫描电镜、透射电镜、傅里叶红外及差示扫描量热法研究不同SiO₂含量的PES/SiO₂杂化材料材料性能.结果表明,当PES/SiO₂杂化材料中SiO₂的质量分数大于10%时可获得有机聚合物链段与无机网络互穿的均匀分散的复合材料.此材料的玻璃化转变温度(Tg)明显提高.     

不同形貌Ni/γ-Al2O3催化剂催化CO甲烷化反应的研究

采用沉淀法分别以乙二醇、水、乙二醇-聚乙二醇600为修饰剂,制备了形貌分别为棒状（a-NiO）、粒状（b-NiO）和片状（c-NiO）结构的NiO催化剂,然后和γ-Al₂O₃通过研混法制得NiO/γ-Al₂O₃催化剂。采用XRD、TEM及H₂-TPR等技术手段对催化剂进行了表征。TEM观察NiO的形貌分别为棒状、粒状和片状。H₂-TPR结果表明,NiO/γ-Al₂O₃催化剂的氧化中心数量顺序为b-NiO/γ-Al₂O₃＜a-NiO/γ-Al₂O₃＜c-NiO/γ-Al₂O₃。XRD结果表明,NiO/γ-Al₂O₃催化剂还原后的Ni晶粒尺寸大小为b-Ni＞a-Ni＞c-Ni。在连续流动固定床反应装置上考察了Ni/γ-Al₂O₃对CO甲烷化反应的催化活性,研究了混合方法和形貌对CO甲烷化反应的影响。结果表明,研混法制得催化剂的活性及稳定性较好。催化剂形貌对CO甲烷化反应的催化活性顺序为c-Ni/γ-Al₂O₃＞a-Ni/γ-Al₂O₃＞b-Ni/γ-Al₂O₃,常压、593K和2500h^-1反应条件下,w_Ni为15% c-Ni/γ-Al₂O₃催化CO合成CH₄选择性及CO转化率分别达90.80%和99.63%。     

MFI型分子膜的制备与H2S/CH4分离性能

采用二次生长法在多孔α-Al₂O₃载体上制备MFI型（ZSM-5和silicate-1）分子筛膜;通过XRD和SEM检测,证明所合成的分子筛膜为致密、交联和无取向的MFI型分子筛膜,厚度为5 μm;单组分气体渗透实验检测中,所制备样品膜的N₂渗透量均小于10^-11 mol/（m²·s·Pa）,可认为其无缺陷;同时,考察了样品分子筛膜对H₂S/CH₄混合气的分离效果,在渗透压分别为0.3和0.5 MPa时,silicate-1分子筛膜的H₂S/CH₄的分离因子分别为1.99和4.44,而ZSM-5分子筛膜的CH₄/H₂S的分离因子分别为6.71和12.85。     

十三氟辛基修饰的疏水有机-无机杂化二氧化硅膜孔结构、氢气分离及水热稳定性

采用1,2-双（三乙氧基硅基）乙烷（BTESE）和十三氟辛基三乙氧基硅烷（PFOTES）为前驱体,在酸性条件下通过溶胶-凝胶法制备了十三氟辛基修饰的有机-无机杂化SiO₂膜材料。利用接触角测量、红外光谱、动态光散射和N₂吸附等测试技术分别对膜材料的疏水性、溶胶粒径和孔结构进行表征,并深入研究有支撑膜材料的氢气渗透、分离性能以及长期水热稳定性。结果表明,十三氟辛基修饰后的膜材料由亲水性变成了疏水性,当n_PFOTES/n_BTESE=0.6时膜材料对水的接触角达到（110.4±0.4）°,膜材料还保持微孔结构,孔径分布在0.5~0.8nm。氢气在修饰后的膜材料中的输运遵循微孔扩散机理,在300℃时,氢气的渗透率达到8.5×10^-7mol·m^-2·s^-1·Pa^-1,H₂/CO₂,H₂/CO和H₂/SF₆的理想分离系数分别为5.49,5.90和18.36,均高于相应的Knudsen扩散分离因子。在250℃且水蒸气物质的量分数为5%水热环境下陈化250h,氢气渗透率和H₂/CO₂的理想分离系数基本保持不变,膜材料具有良好的水热稳定性。     

UV光引发表面接枝两性离子水凝胶层的制备及抗细菌黏附性能

采用聚合和交联的SiO₂有机/无机杂化溶胶作为基材, 通过与两性离子单体层之间的过渡层, 在紫外光作用下引发杂化溶胶和两性离子单体溶液中的双键反应, 使生成的杂化层在基材和表面的两性离子聚合物之间形成辅助性黏接作用, 从而在基材表面构筑两性离子水凝胶层. 通过傅里叶红外光谱(FTIR)、 原子力显微镜(AFM)和接触角测试等方法对所制备的两性离子水凝胶层和杂化层的表面进行了表征. 以空白玻璃片为对照样品, 以金黄色葡萄球菌和大肠杆菌为试验菌, 研究了用两性离子凝胶层修饰的玻璃表面的抗细菌黏附性能. 结果表明, 在SiO₂杂化过渡层中引入线型-Si-(CH₂)₂-O-链段可有效提高杂化过渡层对基材的附着力, 并改善其柔韧性. 与对照样品相比, 用两性离子凝胶层修饰的玻璃表面具有优异的抗菌黏附性能.     

具有不对称孔道结构的小介孔二氧化硅粒子的合成及其高分子杂化膜的构建

利用手性阴离子酸表面活性剂, 采用软模板法制备了具有不对称孔道结构的小介孔二氧化硅(SiO₂)粒子. 将小介孔SiO₂粒子引入聚偏四氟乙烯(PVDF)和聚酰亚胺(PI)中构建了两种有机/无机杂化膜. 利用傅里叶变换红外光谱(FTIR)、 透射电子显微镜(TEM)、 扫描电子显微镜(SEM)和比表面积分析等表征了小介孔SiO₂粒子和有机/无机杂化膜的微结构, 并通过超滤实验和气体渗透实验分别考察两种杂化膜的性能. 研究结果表明, 表面含有大量亲水基团的小介孔SiO₂粒子具有规则有序排列的孔道结构, 该孔道结构呈现螺旋扭曲和不对称性. 构建的两种有机/无机杂化膜的极性显著提升, 进而有效增强了PVDF杂化膜的膜通量和抗污染性能及PI杂化膜对CO₂气体的分离性能, 克服了高分子膜的博弈效应(Trade-off效应). 另外, SiO₂的小介孔孔道还可以在PI杂化膜中引入优先通过CO₂分子的限域传质通道, 加速了CO₂气体在杂化膜中扩散. 但过多小介孔SiO₂粒子的加入导致其在高分子基质中团聚, 削弱杂化膜的极性和亲水性, 从而降低了两种杂化膜的分离性能.     

Highly hydrothermally stable microporous silica membranes for hydrogen separation

Fluorocarbon-modified silica membranes were deposited on gamma-Al2O3/alpha-Al2O3 supports by the sol-gel technique for hydrogen separation. The hydrophobic property, pore structure, gas transport and separation performance, and hydrothermal stability of the modified membranes were investigated. It is observed that the water contact angle increases from 27.2+/-1.5 degrees for the pure silica membranes to 115.0+/-1.2 degrees for the modified ones with a (trifluoropropyl)triethoxysilane (TFPTES)/tetraethyl orthosilicate (TEOS) molar ratio of 0.6. The modified membranes preserve a microporous structure with a micropore volume of 0.14 cm3/g and a pore size of approximately 0.5 nm. A single gas permeation of H2 and CO2 through the modified membranes presents small positive apparent thermal activation energies, indicating a dominant microporous membrane transport. At 200 degrees C, a single H2 permeance of 3.1x10(-6) mol m(-2) s(-1) Pa(-1) and a H2/CO2 permselectivity of 15.2 were obtained after proper correction for the support resistance and the contribution from the defects. In the gas mixture measurement, the H2 permeance and the H2/CO2 separation factor almost remain constant at 200 degrees C with a water vapor pressure of 1.2x10(4) Pa for at least 220 h, indicating that the modified membranes are hydrothermally stable, benefiting from the integrity of the microporous structure due to the fluorocarbon modification.     

Structure of hybrid organic–inorganic sols for the preparation of hydrothermally stable membranes

A procedure for the preparation of hybrid sols for the synthesis of organic–inorganic microporous materials and thin film membranes is reported. We describe silane reactivity and sol structure for acid-catalysed colloidal sols from mixtures of either tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES), or bis(triethoxysilyl)ethane (BTESE) and MTES. Early-stage hydrolysis and condensation rates of the individual silane precursors were followed with ²⁹Si liquid NMR and structural characteristics of more developed sols were studied with Dynamic Light Scattering. Condensation was found to proceed at more or less similar rates for the different precursors. Homogeneously mixed hybrid colloids can therefore be formed from precursor mixtures. The conditions of preparation under which clear sols with low viscosity could be formed from BTESE/MTES were determined. These sols were synthesised at moderate water/silane and acid/silane ratios and could be applied for the coating of defect-free microporous membranes for molecular separations under hydrothermal conditions.     

Rh-Au/γ-Al2O3 三效纳米催化剂的制备与表征

采用超声辅助膜扩散还原法 (UAMR) 和等体积浸渍法 (IMP) 制备了 Rh/γ-Al2O3 和 Rh-Au/γ-Al2O3 催化剂, 考察了它们的三效模型反应 (CO+O2, C3H8+O2, CO+NO 和 C3H6+NO+O2) 活性. H2-O2 滴定和透射电镜结果表明, UAMR 法制得的 Rh/γ-Al2O3 和 Rh-Au/γ-Al2O3 催化剂的金属分散度分别为 45.3% 和 40.1%, 金属粒子表面积分别为 199.6 和 133.0 m2/g, 金属粒子平均粒径小于 3 nm. 对于三效模型反应, 与 IMP 法制备的催化剂相比, UAMR 法制备的 Rh/γ-Al2O3 和 Rh-Au/γ-Al2O3 具有更高的初始活性, 其中后者的活性也高于或接近于 IMP 法制备的 Rh/γ-Al2O3 催化剂. 催化剂经高温老化处理后, 活性均有所下降. UAMR 是一种新颖的负载型纳米催化剂的制备方法, 具有潜在的应用前景.     

Influence of Sol-Gel Synthesis Parameters on the Microstructure of Particulate Silica Xerogels

The influence of key sol-gel synthesis parameters on the pore structure of microporous silica xerogels was investigated. The silica xerogels were prepared using an acid-catalyzed aqueous sol-gel process, with tetraethoxysilane (TEOS) as the silicon-containing precursor. At high H2O : TEOS ratios, sols synthesized at pH 2–3 yielded minimum values of mean micropore diameter and micropore volume. Analysis of the resulting Type I nitrogen adsorption isotherms and the equilibrium adsorption of N(C4F9)3 indicated micropore diameters for these xerogels of less than approximately 10 Å.Xerogel micropore volumes corresponding to sols prepared at pH 3 and an H2O : TEOS ratio of r = 83 were consistent with nearly close packing of silica spheres in the xerogel. Xerogel microstructure was only weakly dependent upon H2O : TEOS ratio during sol synthesis for r > 10. Xerogel micropore volume increased rapidly with sol aging time during an initial induction period of particle formation. However, the xerogel microstructure changed only slowly with time after this initial period, suggesting potential processing advantages for the particulate sol-gel route to porous silica materials.Surface adsorption properties of the silica xerogels were investigated at ambient temperature using N2, SF6, and CO2. CO2 adsorbed most strongly, SF6 also showed measurable adsorption, and N2 adsorption was nearly zero. These results were consistent with the surface transport of CO2, and to a lesser extent SF6, observed in gas permeation studies performed through thin membrane films cast from similarly prepared silica sols.     

用辛烷基硫醇单层保护Au纳米粒子制备CO氧化催化剂Au/γ-Al2O3

采用两相法合成出含活性组分Au的辛烷基硫醇单层保护Au纳米粒子(C8AuNPs)的正己烷溶胶, 用“逐次浸润”法将C8AuNPs负载在γ-Al2O3上, 经真空干燥及活化处理制得Au/γ-Al2O3催化剂. 所制得的Au催化剂前体C8AuNPs/γ-Al2O3表面Au粒子平均粒径可控制在2-3 nm范围内, 且分布比较单一; 催化剂活性评价600 h后, 其表面Au的粒径仍主要分布在2-4 nm范围内; 真空干燥温度影响Au催化剂的粒子尺寸和催化活性, 随着真空干燥温度的提高, Au纳米粒子的粒径增大. 将所制备的催化剂用于低温CO氧化反应, 催化活性评价结果表明, 经25 ℃真空干燥制得的2.5%(质量分数, w)Au/γ-Al2O3具有较高的活性和长期稳定性, 其催化CO完全转化的最低温度为-19 ℃, 在15 ℃下CO完全转化时Au/γ-Al2O3的单程寿命至少900 h; 4.0%(w) Au/γ-Al2O3在15 ℃和进料中含水条件下对CO完全氧化的单程寿命不低于2000 h, 可见催化剂具有强的抗潮湿中毒特性. 综合上述实验结果, 讨论了影响Au/γ-Al2O3催化剂活性的可能因素.     

五元交互体系Li+,Na+,K+//CO32-,Cl--H2O在298.15K的相平衡研究

针对西藏扎布耶盐湖卤水组成,采用等温溶解平衡法研究了五元交互体系Li+,Na+,K+//CO32-,Cl--H2O于298.15K时的相平衡,并绘制了相图(空间立体图和Li2CO3饱和的投影图).结果表明,该五元体系相图含有7个结晶区、13条单变量线和4个无变量点.7个结晶区由6个单盐结晶区和1个复盐结晶区组成,分别为LiCl·H2O,NaCl,KCl,Li2CO3,K2CO3·3/2H2O,Na2CO3·10H2O和NaKCO3·6H2O,没有形成固溶体和天然碱(Na2CO3·NaHCO3·2H2O).4个无变量点标记成K1,K2,K3和K4,所对应的平衡固相盐分别是:Li2CO3+NaKCO3·6H2O+Na2CO3·10H2O+KCl,Li2CO3+NaKCO3·6H2O+K2CO3·3/2H2O+KCl,Li2CO3+NaCl+KCl+LiCl·H2O和Li2CO3+NaCl+Na2CO3·10H2O+KCl.     

Understanding the effect of cobalt particle size on Fischer-Tropsch synthesis: surface species and mechanistic studies by SSITKA and kinetic isotope effect

Co/γ-Al(2)O(3) catalysts with particle sizes in the range of 4-15 nm were investigated by isothermal hydrogenation (IH), temperature programmed hydrogenation (TPH), and steady-state isotopic transient kinetic analysis (SSITKA). Kinetic isotope effect experiments were used to probe possible mechanisms on Co/γ-Al(2)O(3) with different particle size. It was found that CO dissociated on Co/γ-Al(2)O(3) catalysts at 210 °C. The total amount of CO(2) formed following the dissociation depends on the cobalt crystal size. O-Co binding energy was found to be highly dependent on the Co metal particle size, whereas similar C-Co binding energy was found on catalysts with different Co particle size. Very strongly bonded carbon and oxygen surface species increased with decreasing particle size and acted as site blocking species in the methanation reaction. SSITKA experiments showed that the intrinsic activity (1/τ(CH(x))) remained constant as the particle size increased from 4 to 15 nm. The number of surface intermediates (N(CH(x))) increased with increasing particle size. The apparent activation energies were found similar for these catalysts, about 85 kJ/mol. D(2)-H(2) switches further confirmed that the particle size did not change the kinetically relevant steps in the reaction. The reactivity of the active sites on the 4 nm particles was the same as those on the 8, 11, and 15 nm particles, and only the number of total available surface active sites was less on the 4 nm particles than on the others.     

Focus on moisture-resistance and hydrophobicity of SiO<Subscript>2</Subscript> antireflective film improved by poly(isopropylene oxide) glycerolether

The poly(isopropylene oxide) glycerolether (PO) modified silica antireflective (AR) coating films were prepared by sol–gel method. The properties of the silica sols and AR films were characterized by particle size analyzer, transmission electron microscope, UV–Vis spectro-photometry, spectroscopic ellipsometer and contact angle measurement. The results show that PO addition has inconspicuous effect on the transmittance of AR coatings; the maximum transmittance reached 99.5%. Thicknesses of films increase and refractive index decrease with increase of PO concentration. The contact angle with water for the silica films with and without PO was 68.5^o and 28.5^o, respectively, which indicates an increase of hydrophobicity of the modified coating. When the films were placed in 95% relative humidity at room temperature for 30 days, transmittance loss for the unmodified and modified silica films were 2.5 and 0.6% respectively. Moisture-resistance of the film is greatly improved by PO addition.     

SiO2 溶胶及其静电自组装薄膜的制备

Silica sols were prepared by hydrolysis of Si（OC2H5）4（TEOS）using HCl,NH3·H2O,HCl/NH3·H2O as catalyzers,and the different granularities of SiO2 sols which catalyzed by HCl first and then NH3·H2O have the same terminal pH value were prepared. The silica colloidal particles were investigated with Transmission Electron Microscope（TEM）. The results showed sol catalyzed by HCl possesses very little particle,catalyzed by NH3·H2O has particle configuration,catalyzed by HCl/NH3·H2O possesses consecutive configuration. Poly（diallyldimethylammonium chloride）（PDDA）and SiO2 nanoparticulate complex thin films were prepared by electrostatic self-assembly multiplayer（ESAM）method. After assembling films,thin films surface conformation was observed with Electron Microscope and their transmittance was tested with 721 Spectrophotometer. The results showed that the silica sol catalyzed with HCl is not good for the fabrication of ESAM films and the silica sol catalyzed with HCl first and then NH3·H2O or by NH3·H2O only are very suitable for ESAM film fabrication. TEM data indicate that the microstructure of PDDA/ SiO2 prepared from silica sol catalyzed with HCl first and then NH3·H2O is consecutive and that the microstructure of PDDA/ SiO2 prepared from silica sol catalyzed by NH3·H2O only is particulate-parking like. The dependence of the transmittance of assembled films on the bilayer number of the films and the anti-scratching properties of the films were investigated. The results show that PDDA/ SiO2 films prepared from silica sol catalyzed by NH3·H2O only possess higher transmittance but lower anti-scratching properties. The effect of granularity of sols on optical performances of the thin films was studied,results showed the less the granularity of sol,the better the optical performances. For the sake of improving the light transmittance of films,we can reduce the granularity of sol,but it may play down its mechanical damage resist intensity.