高稳定性的SiO2/HKUST-1复合膜的制备及氢气分离性能

以多孔二氧化硅片为基底,通过接枝硅烷偶联剂制备高稳定性能的SiO2与HKUST-1复合无机膜.具体做法是将3-氨丙基甲基二甲氧基硅烷拌接枝在SiO2片上,在SiO2片表面上接枝的氨基可以参与生长HKUST-1膜,从而制备出大面积连续致密的HKUST-1无机膜.通过X-射线衍射(XRD)、扫描电子显微镜(SEM)、热重分析(TGA)、单组份及混合组分的渗透流量测试装置对得到的复合无机膜的化学结构、表面形貌、热稳定性和气体分离性能进行了表征.结果表明:制备的复合无机膜具有与其晶体一致的晶相,且连续致密,无缺陷;同时具有很好的热稳定性和机械稳定性.气体渗透流量测试结果显示该复合无机膜对氢气具有很好的选择性,可以用来分离和提纯氢气.     

一种无机膜的制备及其CO2分离性能的研究

用多孔的SiO2片作载体,通过水热合成法在其表面上制备出了大面积的无机沸石分子筛膜.通过扫描电子显微镜(SEM)、X-射线衍射仪(XRD)、CO2与其他气体的气体分离测试等方法对得到的无机沸石分子筛膜的微观表面形貌、表面化学结构、机械稳定性以及CO2气体的分离和回收性能进行了细致的分析表征和探索研究.SEM和XRD结果...     

疏水SiO_2/PTFPMS杂化复合膜的制备及其气体分离性能

为了提高气体分离膜的耐溶胀特性,以多孔聚醚酰亚胺(PEI)为支撑层,采用溶液共混法制备了疏水SiO2/PTFPMS杂化复合膜,研究了疏水SiO2质量共混比对膜形态、耐溶胀性以及不同操作压差下的纯气渗透分离性能的影响。光学显微照片显示,当共混比不超过0.018时,杂化膜的透明度较高,表明疏水SiO2与PTFPMS具有较好的相容性;当SiO2与PTFPMS的共混比超过0.018时,SiO2团聚明显。SEM表征结果显示,杂化膜表面光洁,断面杂化涂层紧密贴合支撑层。疏水SiO2/PTFPMS杂化膜在异辛烷中的溶胀度为0,在乙酸乙酯中的溶胀度比PTFPMS均质膜的下降了11.9%,显示了其优异的耐溶胀性能。在操作压力为1.0 MPa,操作温度为25℃下,SiO2共混比为0.012时,疏水SiO2/PTFPMS杂化复合膜的CO2渗透通量达到最高156.1GPU,CO2/N2选择性为15.86。     

用于CO_2分离的[bmim][Tf_2N]-PAN共混膜制备及性能

咪唑类离子液体对CO2有良好的溶解性,利用其进行气体分离可以同时提高膜对CO2的选择性和渗透性。利用1-丁基-3-甲基咪唑双三氟甲磺酰亚胺([bmim][Tf2N])离子液体对CO2具有较高的溶解选择性,将[bmim][Tf2N]和聚丙烯腈(PAN)共混制备膜液,涂覆在聚丙烯(PP)支撑层上,利用溶剂蒸发法制备共混复合膜。结果表明,[bmim][Tf2N]的添加对复合膜气体分离性能有明显提高,在离子液体质量分数达到50%后,离子液体逐渐变为连续相,增加了CO2气体的传递通道;气体渗透性能显示其CO2渗透速率可达34.76 GPU,CO2/N2和CO2/CH4理想选择性分别可达49.51和25.14;在随后改变操作压力和测试温度的实验中发现,增大跨膜压差和测试温度均有利于复合膜渗透速率的提升。     

镍掺杂SiO_2膜的制备及CH_4/CO_2气体分离性能

以正硅酸乙酯(TEOS)为前驱体,六水合硝酸镍(Ni(NO3)2·6H2O)为镍源,采用溶胶--凝胶法制备镍掺杂SiO2膜。研究了水用量及镍含量对镍掺杂SiO2膜的结构及形貌的影响,并对其进行CH4、CO2气体渗透性能测试。结果表明:水酯比为5.5时,制备的10%Ni掺杂SiO2膜具有良好的微孔结构,且孔径约为1.16nm,孔隙率为64.9%。一部分Ni元素以Ni和NiO晶体形式填充于SiO2孔道内,另一部分以Si—O—Ni形式进入SiO2骨架。Ni掺杂SiO2膜在84h内能够保持良好的气体渗透性能,表现出比纯SiO2膜更好的水热稳定性。CH4和CO2的气体渗透通量分别为1.56×10--7和0.64×10--7 mol/(m2·s·Pa),CH4/CO2气体分离因子达到2.43。     

TiO_2/ZnO纳米多孔复合膜制备及光催化性能研究

分别采用水热处理和添加有机物的方法制备了TiO2/ZnO纳米多孔复合膜,利用XRD、SEM、TEM和EDS对薄膜进行了分析表征,通过甲基橙降解研究了多孔膜的光催化性能。结果表明:采用这两种方法都可获得具有孔洞特征的多孔复合膜,对添加有机物法制备的多孔膜进行的光催化降解实验表明该多孔膜光催化性能明显优于致密复合膜。     

PANI/SiO2-VTEO/SiO2疏水复合膜的制备及防腐蚀性能

以硅酸乙酯(TEOS)为前驱体,通过溶胶凝胶法制备二氧化硅(SiO2)溶胶,并以乙烯基三乙氧基硅烷(VTEO)对其改性,得到改性SiO2溶胶(VTEO/SiO2);同时制备磷酸掺杂聚苯胺(PANI)接枝SiO2复合粒子(PANI/SiO2)。将改性溶胶和复合粒子均匀混合后在Q235钢表面制备了PANI/SiO2-VTEO/SiO2复合膜。利用红外光谱(FTIR)分析了改性SiO2溶胶和PANI接枝SiO2的化学结构;通过扫描电子显微镜(SEM)分析了复合膜的形貌;利用接触角测试仪测试了复合膜的疏水性能;采用电化学阻抗谱(EIS)、开路电位(OCP)、极化曲线对制备的PANI/SiO2-VTEO/SiO2复合膜进行防腐蚀性能研究。结果表明,复合膜的水接触角为150°,表现出良好的疏水性能;复合膜具有较高的电化学阻抗(5.0×106Ω)和开路电位(-0.18 V),较低腐蚀电流密度(1.18×10-8A/cm2),腐蚀速率仅为0.000 1 mm/a,表现出了良好的防腐蚀性能。     

用PVP水解物制备CO2固载膜及膜的性能

以自由基聚合合成了聚乙烯基吡咯烷酮 (PVP) ,并用其水解产物聚N 乙烯基 γ 氨基丁酸钠 (PVSA)和聚砜 (PS)超滤膜制备了PVSA/PS复合膜 ;用红外光谱、X射线衍射等方法研究了PVP及其水解产物PVSA的结构 ,证实了PVSA含有可作为CO2 载体的仲胺基与羧基 ;测试了复合膜的透气性能及对CO2 /CH4的选择性 .结果表明 ,在 2 6℃ ,压力为 1333Pa时 ,CO2 渗透速率可达 5 4 6× 10 -7cm3 (STP)·cm-2 ·s-1·Pa-1,CO2 /CH4的理想分离因子达到 2 12 1.随着进料气压力的增大 ,CO2 /CH4的分离因子及CO2 的渗透速率均呈下降趋势 .依据膜的渗透通量随压力的变化特性以及不同状态下膜的红外光谱 ,分析了膜对CO2 的促进传递机理     

聚乙烯醇-二氧化硅/聚丙烯腈杂化复合膜渗透蒸发分离己内酰胺/水溶液

制备了以聚乙烯醇(PVA)填充纳米SiO2改性膜为活性层,聚丙烯腈(PAN)超滤膜为底膜的PVA-SiO2/PAN杂化复合膜,并用于己内酰胺(CPL)脱水。用FTIR,SEM,XRD,TGA分别对膜进行了表征,并考察了膜中纳米SiO2粒子的质量分数、进料组分质量分数和温度对复合膜分离性能的影响。结果表明,引入纳米SiO2后,杂化膜的热稳定性明显提高。当膜中纳米SiO2质量分数为1.0%时,复合膜渗透蒸发分离性能最佳。60℃下此复合膜用于分离质量分数为40%的CPL溶液时,其总通量和分离因子分别达到2 177 g/(m2.h)和349。     

仿生制备SiO2分离膜的实验

以表面活性剂十六烷基三甲基溴化铵(CTAB)在溶液中的自组装胶束为有机模板,对无机前躯体正硅酸乙酯(TEOS)的水解缩聚过程进行调控,于SiO2 无机膜中复制出了具有自组装体形状的三维孔结构。孔径分布测定结果表明优化物料条件下制备出的非担载SiO2 膜具有 1. 8nm的最可几孔径,平均孔径为 5. 3nm。对比传统的sol gel制膜方法,其孔径分布不受灼烧条件的影响。该膜的广角XRD分析结果表明组成介孔壁面的SiO2 为非晶型结构,该膜的小角度XRD分析结果进一步表明,膜内介孔道的排列形式为三维空间上的无序网络结构。将优化物料条件下的混合物旋涂于多孔Al2O3 陶瓷载体上,进一步制备出了SiO2 分离膜,该膜的SEM表征和气体渗透性能测定结果表明其完整性能较好。     

Self-organized nano-crystallisation of BaF2 from Na2O/K2O/BaF2/Al2O3/SiO2 glasses

In glasses with the compositions (100 ? x)(2Na₂O·16K₂O·8Al₂O₃·74SiO₂)xBaF₂ (with x = 0 to 6), the glass transition temperature decreases with increasing BaF₂-concentration. Samples with x = 6 were thermally treated at temperatures in the range from 500 to 600 °C for 5–160 h. This leads to the crystallisation of BaF₂. The quantity of crystalline BaF₂ increases with increasing time of thermal treatment, while the mean crystallite size remains constant within the limits of error. The glass transformation temperature of partially crystallised samples increases with increasing crystallisation time and approaches a value equal to the temperature, at which the samples were treated. This is explained by the formation of a highly viscous layer enriched in SiO₂ which is formed during crystallisation. This layer acts as a diffusion barrier and hinders further crystal growth.     

Prediction of Immiscibility Boundaries of the Systems K2O-SiO2, K2O-Li20-SiO2, K20-Na2O-Si02, and K2O-BaO-SiO2

In earlier work, a prediction method of the immiscibility boundary of a ternary silicate glass system was developed involving two known binary immiscibility boundaries and a measured immiscibility temperature of one ternary glass composition. In the present work, the method is extended to the case where one of the two binary immiscibility boundaries is not known and is applied as an example to ternary silicate systems containing K₂O. First, the immiscibility boundary of the system K₂O-SiO₂ is estimated by measuring the immiscibility temperatures of three glasses in the system K₂O-Li₂O (or Na₂O)-SiO₂. Using this result the immiscibility boundaries of the systems K₂O-Li₂O-SiO₂, K₂O-Na₂O-SiO₂, and K₂O-BaO-SiO₂ are estimated. The results agree reasonably well with the experimentally determined immiscibility temperatures at selected compositions.     

The System Na2O-CaO-SiO2-H2O

A portion of the quaternary phase diagram for Na₂O-CaO-SiO₂-H₂O has been constructed. Plotting concentrations as their 10th roots allows compounds having solubilities which differ by several orders of magnitude to be represented on a single diagram. The compositional relationships among sodium-substituted calcium silicate hydrate, calcium-substituted sodium silicate hydrate, calcium bydroxide, a quaternary compound of approximate composition 0.25Na₂O · CaO · SiO₂· 3H₂O, sodium hydroxide monohydrate, and miscellaneous sodium silicate hydrates are presented. The quaternary diagram constructed shows the quaternary compound to exist in equilibrium with sodium-substituted calcium silicate hydrate and calcium hydroxide. Conditions in concrete pore solutions which favor the formation of this quaternary compound may also favor the occurrence of the alkali-silica reaction.     

复合固体超强酸SO42-/ZrO2-Al2O3催化合成乳酸正丁酯的研究

合成了几种不同Zr、Al原子比的SO42-/ZrO2-Al2O3复合固体超强酸,将其用于催化乳酸与正丁醇的酯化反应,均有较好的催化活性,尤以ZrAl=12的催化效果最好,经济性优于ZrO2超强酸催化剂.其最佳反应条件为酸醇摩尔比为13,催化剂用量为乳酸质量的10%,反应时间2～2.5h,酯化率达96.9%.该催化剂具有制备容易、催化活性高、不污染环境、可重复使用的优点.     

Some Properties of the System Na2O-NaF-B2O2-H2O

It was first shown that the enamel slips which have the best suspnding characteristics contain equal amounts of Na₂O and B₂O₃ and at least a moderate amount of NaF. The solubilities of mixtures of Na₂O, NaF, and B₂O₃ were then investigated. The pH of these solutions and the primary crystalline phases separating on evaporation also were determined. The solubility data obtained at room temperature were summarized. When the solutions were evaporated, NaF was the first crystalline phase to separate from a large proportion of the mixtures investigated. It was concluded that the desirable handling characteristics of enamels whose mill liquors contain the proper proportion of Na₂O, NaF, and B₂O₃ are not due to the formation of complex salts but to the following combination of properties: (1) the presence of salts with a moderate solubility which changes very slightly with temperature, (2) a moderate pH of about 10 in a probably well-buffered solution, (3) a relatively stable crystalline material, NaF, as a primary phase, and (4) a secondary phase which crystallizes slowly with relatively little shrinkage.     

固体超强酸SO^2—4／TiO2催化合成尿囊素的研究

用固体超强酸SO42/TiO2为催化剂,以尿素和乙醛酸为原料合成了尿囊素。得到最佳条件为TiO2在1mo1·L-1H2SO4溶液中浸渍12h,再在600℃焙烧3h;尿素与乙醛酸摩尔比3.51,催化剂9％,时间3h,温度72℃～75℃,产率达57.4％。     

Photocatalytic activity of Cu2O/TiO2, Bi2O3/TiO2 and ZnMn2O4/TiO2 heterojunctions

Cu₂O/TiO₂, Bi₂O₃/TiO₂ and ZnMn₂O₄/TiO₂ heterojunctions were studied for potential applications in water decontamination technology and their capacity to induce an oxidation process under VIS light. UV–vis spectroscopy analysis showed that the junctions-based Cu₂O, Bi₂O₃ and ZnMn₂O₄ are able to absorb a large part of visible light (respectively, up to 650, 460 and 1000 nm). This fact was confirmed in the case of Cu₂O/TiO₂ and Bi₂O₃/TiO₂ by photocatalytic experiments performed under visible light. A part of the charge recombination that can take place when both semiconductors are excited was observed when a photocatalytic experiment was performed under UV–vis illumination. Orange II, 4-hydroxybenzoic and benzamide were used as pollutants in the experiment. Photoactivity of the junctions was found to be strongly dependent on the substrate. The different phenomena that were observed in each case are discussed.     

Phase Diagrams for the Systems MgCl2-MgF2, CaCl2-MgF2, and NaCl-MgF2

Equilibrium phase diagrams for the systems MgCl₂-MgF₂, CaCl₂-MgF₂ and NaCl-MgF₂ were determined by differential thermal analysis, thermal analysis, and temperature-composition equilibrium techniques. Simple eutectics were observed at 78.0±0.5 mol% MgCl₂ and 628°±2°C in the MgCl₂-MgF₂ system, at 87.5±0.5 mol% CaCl₂ and 694°±2°C in the CaCl₂-MgF₂ system, and at 95.5±0.5 mol% NaCl and 786°±3°C in the NaCl-MgF₂ system. The phase diagrams determined for these systems were compared with phase diagrams that were computed using Temkin's model. The phase diagrams of the CaCl₂-MgF₂ and NaCl-MgF₂ systems were also compared with diagrams that were computed using the expression suggested by Flood et al. for reciprocal systems. The experimentally determined and computed phase diagrams agreed for the MgCl₂-MgF₂ system but not for the CaCl₂-MgF₂ and NaCl-MgF₂ systems.     

Crystallization of zeolite L from Na2O-K2O-Al2O3-SiO2-H2O system

Zeolite L powder was prepared from the substrate mixture of Na₂O-K₂O-Al₂O₃-SiO₂-H₂O system at temperatures of 373-443 K. In order to investigate the factors which influence the synthesis outcome, a reference system which yields zeolite L in a reproducible manner was chosen and subjected to controlled changes in synthesis parameters. The crystalline zeolite L samples obtained were characterized by elemental chemical analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM). It was established that phase purity, morphology, and the size of crystals of crystalline product were affected by molar ratios of the substrate, such as SiO₂/Al₂O₃, (K₂O+Na₂O)/SiO₂, Na₂O/(K₂O+Na₂O), and H₂O/(K₂O+Na₂O). Amorphous silica powder (Zeosil) was the preferred silica source, and the crystallization rate was promoted by introducing gel aging, seeding, and rapid heating rate.