溶胶－凝胶法制备的SiO_2膜的结构与性质

本文用ＴＥＯＳ和硅溶胶作原料，用溶胶一凝胶法制备了无支撑体和有支撑体的ＳｉＯ２膜．用ＴＥＯＳ制得的无支撑体ＳｉＯ２膜，无１．７ｎｍ以上的微孔，由硅溶胶制得的无支撑体ＳｉＯ２膜平均孔径为７．５ｎｍ，且孔径分布集中，这种差异主要来自于由不同原料制备的溶胶，其聚合物分子具有不同的形态和生长模式．用ＴＥＯＳ作原料，在无过渡层的α－Ａｌ２Ｏ３多孔支撑体上制得了无大孔缺陷、厚约１５μｍ的ＳｉＯ２膜，膜对ＢＳＡ的百分截留率为７５．８％．在有过渡层的α－Ａｌ２Ｏ３上制得的ＳｉＯ２膜的纯Ｎ２渗透表现为Ｋｎｕｄｓｅｎ扩散特征．起超滤和扩散作用的是ＳｉＯ２膜层内部的缺陷微孔．     

超细孔二氧化硅膜的制备研究

以正硅酸乙酯（ＴＥＯＳ）为原料，采用溶胶－凝胶技术在多孔陶瓷载体上制备出具有３．０ｎｍ孔径的ＳｉＯ２陶瓷膜。考察了制膜过程中ＴＥＯＳ、乙醇、水的相对量；酸碱催化和ｐＨ值；热处理温度及成膜助剂对膜性能的影响。在自制的单管膜分离器上，测定了Ｏ２、Ｎ２、ＣＯ２和ＣＨ４等气体在ＳｉＯ２陶瓷膜上的渗透性能。     

溶胶—凝胶法制备的SiO2膜的结构与性质

本文用ＴＥＯＳ和硅溶胶作原料，用溶胶－凝胶法制备了无支撑体和有支撑体的ＳｉＯ２膜。用ＴＥＯＳ制得的无支撑体ＳｉＯ２膜，无１．７ｎｍ以上的微孔，由硅溶胶制得的无支撑体ＳｉＯ２膜平均孔径为７．５ｎｍ，且孔径分布集中，这种差异主要来自于由不同原料制备的溶胶，其聚合物分子具有不同的形态和生长模式。用ＴＥＯＳ作原料，在无过滤层的α－Ａｌ２Ｏ３多孔支撑体上制得了无大孔缺陷、厚约１５μｍ的ＳｉＯ２膜，膜对ＢＳＡ     

硅藻上一莫来石陶瓷负载SiO2膜的制备与表征

将液晶模板技术与溶胶－凝胶法相结合,制备了硅藻土－莫来石陶瓷（Ｋ－Ｍ）负载型ＳｉＯ２膜。表征实验结果表明：ＳｉＯ２膜层与ＴｉＯ２过渡膜层间通过Ｓｉ－Ｏ－Ｔｉ键的价联方式形成了紧密、稳定的伦合型复合膜;ＳｉＯ２膜孔径集中在４～５ｎｍ,孔分布较为均匀;Ｋ－Ｍ负载ＳｉＯ２膜管对气体具有较强的渗透能力,并有较好的气体分离作用根据实验结果探讨了模板剂的性质及用量对ＳｉＯ２膜孔结构的决定性作用。     

纳米级微孔SiO_2玻璃材料制备技术研究Ⅲ.纳米级微孔SiO_2玻璃球的研制

以水玻璃为原料，用溶胶凝胶法，在着重研究了溶胶中ＳｉＯ２含量和湿凝胶干燥温度对产品性能影响的基础上，优选工艺条件，制得了粒径为１～２ｍｍ，孔径为１～６ｎｍ，比表面积达３６０～７００ｍ２／ｇ范围的多种纳米级微孔ＳｉＯ２玻璃球。比表面积和孔径数据表明，本文方法可作为制备纳米级微孔基质材料的一种成本较低廉的新工艺。     

超薄γ－Al_2O_3陶瓷膜的合成原位造粒成膜法

从无机铝盐出发，采用原位造粒技术，在自制的圆板状α－Ａｌ２Ｏ３载体表面上成膜，研究了原位造粒成膜的一些影响因素，并与溶胶－凝胶法以乙醇铝制备的载体γ－Ａｌ２Ｏ３膜进行了孔结构、表面状态和气体渗透性等性能和成膜机理的比较．结果表明：原位造粒法从无机铝盐出发可以制备具有微孔结构无针孔的γ－Ａｌ２Ｏ３膜．而且，具有如下优良品性：（１）膜的厚度薄而均匀、完好率大，膜厚度可控制在～１μｍ的水平，比乙醇铝水解溶胶－凝胶法制得的膜厚度～５μｍ薄得多；（２）具有良好的气体渗透性能，在保持基本相同的分离因子增量的情况下，其渗透率的减少量比乙醇铝水解溶胶－凝胶法的少得多；（３）在载体表面的微孔口原位造粒，粘着性好，不易脱落，而且粒径和孔径的大小可以通过浸渍时间及氨处理来调节等．     

硅粉在高压氮气中自蔓延燃烧合成氮化硅的反应机理

本文对Ｓｉ粉在高压氮气中自蔓延燃烧合成（ＳＨＳ）Ｓｉ３Ｎ４的反应机理进行了研究。燃烧反应中Ｓｉ以蒸汽形式与Ｎ２在Ｓｉ３Ｎ４晶种表面反应，反应分为两个主要阶段：（１）动力学反应阶段：Ｓｉ蒸汽不需经过扩散直接与Ｎ２进行反应，反应速度快；（２）扩散控制反应阶段：Ｓｉ蒸汽经过Ｎ２气层扩散到Ｓｉ３Ｎ４晶种表面与Ｎ２反应，反应受扩散控制，速度较慢。     

纳米级微孔SiO2玻璃材料制备技术研究：Ⅲ.纳米级微孔SiO2玻璃球的研制

以水玻璃为原料，用溶胶凝胶法，在着重研究了溶胶中ＳｉＯ２含量和湿凝胶干燥温度对产品性能影响的基础上，优选工艺条件，制得了粒径为１～２ｍｍ，孔径为１～６ｎｍ，比表面积达３６０～７００ｍ＾２／ｇ范围的多种纳米级微孔ＳｉＯ２玻璃球。比表面积和孔径数据表明，本文方法可作为制备纳米级微孔基质材料的一种成本较低廉的新工艺。     

沸石粒子充填型SiO2基分子筛复合膜研究

利用水热合成技术制备纳米级沸石粒子,将其按一定配比中入到ＳｉＯ２溶胶中,搅拌均匀,经涂膜、干燥、二次水热处理和烧结制香ＳｉＯ２基沸石微粒子分子筛复合膜。膜的平均孔径明显小于纯ＳｉＯ２膜,孔径分布均匀、单一。其主要机理是沸石粒子充填于ＳｉＯ２孔道之中,对孔起修饰作用,改善了膜的孔结构及分布。     

氟磷灰石热炭还原的动力学研究

本文对磷氟磷灰石的ＳｉＯ２存在下被炭还原过程中的物质传递及反应过程进行了探讨，导出了动力学方程，结合动力学实验数据回归表明反应受反应物在熔融液相中的扩散控制。     

An Approach to Calculate Thermodynamic Properties of Mixtures Including Propane, <Emphasis Type="Italic">n</Emphasis>-Butane,and Isobutane

This paper discusses a mathematical model for computing the thermodynamic properties of propane, n-butane, isobutane, and their mixtures, in the fluid phase using a method based upon statistical chain theory. The constants necessary for computations such as the characteristic temperatures of rotation, electronic state, etc. and the moments of inertia are obtained analytically applying a knowledge of the atomic structure of the molecule. The paper presents a procedure for calculating thermodynamic properties such as pressure, speed of sound, the Joule-Thomson coefficient, compressibility, enthalpy, and thermal expansion coefficient. This paper will discuss, for the first time, the application of statistical chain theory for accurate properties of binary and ternary mixtures including propane, n-butane, and isobutane, in their entire fluid phases. To calculate the thermodynamic properties of Lennard-Jones chains, the Liu-Li-Lu model has been used. The thermodynamic properties of the hydrocarbon mixtures are obtained using the one-fluid theory. Paper presented at the Fifteenth Symposium on Theremophysical Properties, June 22–27, 2003, Boulder, Colorado, U.S.A.     

A nonlinear correlation of high-pressure vapor-liquid equilibrium data for ethylene +n-butane showing inconsistencies in experimental compositions

The modified Leung- Griffiths model is applied to the previously unpublished data, tabulated here, of Williams for high-pressure vapor-liquid equilibria of ethylene +n-butane. It is not possible to obtain a highly accurate correlation with the experimentally stated compositions, but evidence is given that those composition measurements may be Suspect, although pressure, temperature, and density data are accurate. A simplex optimization method was used for the parameters of the model. and the compositions were also treated as adjustable parameters. With this method a much more accurate correlation is obtained, but the optimized compositions differ in two of four cases by more than 3% from the stated compositions,Paper presented at the Twelfth Symposium on Thermophysical Properties. June 19–24, 1994, Boulder, Colorado, U.S.A.     

Viscosity and density of liquid mixtures ofn-alkanes with squalane

Viscosity and density measurements are reported for binary liquid mixtures ofn-butane andn-hexane with squalane in the temperature range from 273 to 333 K. The viscosity measurements have been carried out by using a capillary viscometer calibrated with standard liquids. that is. JS5, JSIO, JS20, and water. The uncertainty in the viscosity data was estimated to be ± 1.7%. The density needed for the calculation of the viscosity has been measured by using a glass pycnometer within an accuracy of ±0.04%. In the prediction of the viscosity, the scheme of Assael et al. fails for mixtures of this type differing greatly in size.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994. Boulder, Colorado, U.S.A.     

The Viscosity of Gaseous n-Butane and Its Initial Density Dependence

New relative high-precision measurements of the viscosity of gaseous n-butane were carried out in an oscillating-disk viscometer. Seven series of measurements were performed between 298 and 627 K. in the density range from 0.01 to 0.05 mol·L^–1. Isotherms recalculated from the original experimental data were analyzed with a first-order expansion, in terms of density, for the viscosity. Reduced values of the second viscosity virial coefficient deduced from the zero-density and initial-density viscosity coefficients for n-butane are in good agreement with the representation of the Rainwater–Friend theory. The new experimental data and some data sets from the literature were used to develop a representation for the viscosity of n-butane in the limit of zero density on the basis of the extended principle of corresponding states. It has been shown that an individual correlation is needed to represent the experimental data between 293 and 627 K with an uncertainty of ±0.4%.     

Solubility of polymers in supercritical fluids

The phase separation of solutions of monodisperse polystyrene samples of molecular weight 9000 in pure and also binary mixtures ofn-butane andn-pentane has been examined under both subcritical and supercritical conditions over the whole concentration range using a variable-volume view cell capable of operating at up to 100 MPa and 500 K. The phase behavior of these solutions is discussed in terms of the coexistence curves and the theoretical predictions based on the mean-field lattice-gas theory.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.     

Vapor-Liquid Equilibria of HFC-32/n-Butane Mixtures

The vapor-liquid equilibria of HFC-32 and n-butane mixtures were measured in a temperature range of 283.15 to 313.15 K using a circulation method. The experimental standard uncertainties of temperature, pressure, and composition measurements were estimated to be within 10 mK, 2 kPa, and 0.2% in mole fraction, respectively. The measured data were correlated with the Peng–Robinson (PR) equation of state using Wong and Sandler mixing rules. The relative deviations of the measured bubble-point pressure from the calculated bubble-point pressure as a function of the measured bubble-point pressure were found to be less than 2.5%.     

Vapor-liquid equilibria of ternary mixtures in the critical region on paths of constant temperature and overall composition

High-pressure vapor liquid equilibrium (VLE) data for the ternary mixture ethane +n-butane +n-pentane due to Thodos and co-workers have been correlated by a ternary version of the modified Leung Grifiths model. Data were taken along paths of constant temperature and approximately constant overall composition, and a separate test was made for such constancy. Seventeen different specified overall compositions at four dilTerent temperatures were correlated. In general, agreement between the correlation and data is very good, particularly for those curves that satisfy the test for constant overall composition. The ternary model has been constructed from correlations of each of the three constituent binaries without any further adjustable parameters.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994. Boulder, Colorado, U.S.A.     

Measurements of the Liquid Viscosities of Mixtures of n-Butane, n-Hexane, and n-Octane with Squalane to 30 MPa

The viscosities of liquid mixtures of n-butane, n-hexane, and n-octane with squalane that represent model mixtures of refrigerants with refrigeration oil were measured at temperatures between 273.15 and 333.15 K, and at pressures from 0.1 to 30 MPa, by using a falling body viscometer. The uncertainty of the measurements was estimated to be no larger than 2.9%. The experimental viscosity values were fitted to a Tait-like equation within 2.8%. There are larger deviations between the experimental data and calculated values predicted by the equation of Kanti et al., which is derived from the Flory theory. By introducing an interaction parameter of the energetic mixing rule into the equation, the deviations were significantly reduced.     

Equations of State for Technical Applications. II. Results for Nonpolar Fluids

New functional forms have been developed for multiparameter equations of state for non- and weakly polar fluids and for polar fluids. The resulting functional forms, which were established with an optimization algorithm which considers data sets for different fluids simultaneously, are suitable as a basis for equations of state for a broad variety of fluids. The functional forms were designed to fulfill typical demands of advanced technical applications with regard to the achieved accuracy. They are numerically very stable and their substance-specific coefficients can easily be fitted to restricted data sets. In this way, a fast extension of the group of fluids for which accurate empirical equations of state are available becomes possible. This article deals with the results found for the non- and weakly polar fluids methane, ethane, propane, isobutane, n-butane, n-pentane, n-hexane, n-heptane, n-octane, argon, oxygen, nitrogen, ethylene, cyclohexane, and sulfur hexafluoride. The substance-specific parameters of the new equations of state are given as well as statistical and graphical comparisons with experimental data. General features of the new class of equations of state such as their extrapolation behavior and their numerical stability have been discussed in a preceding article. Results for typical polar fluids will be discussed in a subsequent article.