两步变温晶种法制备丝光沸石膜及其渗透汽化乙酸脱水性能

在水热晶种法基础上采用两步变温晶化以高水硅比(n_H2O/n_SiO2)稀溶液配方为合成液,研制用于渗透汽化(PV)乙酸脱水的丝光沸石膜(MOR膜),考察了变温晶化各段时间、水硅比与氟离子对 MOR膜的形貌与分离性能的影响规律。结果表明：高温段晶化时间、水硅比与氟离子对MOR膜的形貌、结晶度和膜层厚度产生显著影响,并影响MOR膜渗透气化分离性能;在高温段(150 ℃)和低温段(120 ℃)的晶化时间分别为 18和 6 h,在水硅比为 60且含氟离子体系中所制备的 MOR膜的性能最佳,其对质量分数50%的乙酸水溶液的渗透通量和分离系数分别为1.45 kg·m^-2·h^-1和1 008。     

CVD法制备Sn掺杂MFI分子筛膜及其对乙醇/水体系的分离性能

采用化学气相沉积(CVD)法对MFI分子筛膜进行Sn掺杂, 制备了一种Sn-MFI分子筛膜, 并研究了其渗透汽化分离乙醇/水体系的性能. XRD, ²⁹Si NMR, UV-Vis及分离实验结果表明, 采用CVD法在将Sn引入MFI膜时, 膜层结构基本得到保持, Sn可以进入分子筛骨架, 有效地减少了膜表面的硅羟基缺陷, 提高了膜分离乙醇/水体系时的稳定性. 在SnCl₄用量为3 mL、 修饰时间为1 h时, 所得到的Sn-MFI分子筛膜的渗透汽化分离性能最佳, 并可在60 ℃下分离5%(质量分数)乙醇/水混合物时保持良好的稳定性. 在经过连续50 h渗透气化分离后, 其渗透通量仅从1.52 kg·m^-2·h^-1下降至1.38 kg·m^-2·h^-1, 分离因子从18下降至16.     

含氟体系中高性能T型分子筛膜的合成

含氟体系中,在负载晶种的大孔莫来石支撑体表面快速合成了高性能且取向生长的T型分子筛膜。采用XRD、SEM和MAS NMR等手段对分子筛膜层和粉末进行表征。讨论了添加物、氟硅比、合成温度和合成时间等条件对膜生长与分离性能的影响,并阐述了含氟体系中T型分子筛膜快速晶化的机理。碱金属氟盐的加入促进了T型分子筛晶体层的晶化速率,并对晶体层形貌产生了一定的影响。膜应用于75℃、水/异丙醇(10∶90,w/w)体系的平均渗透通量和分离因子分别为(4.91±0.18)kg·m-2·h-1和7 060±1 130。     

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.     

高性能AlPO4-14分子筛膜的制备及气体分离性能

制备了高性能的AlPO₄-14分子筛膜. 首先通过控制反应溶胶中水和模板剂的含量制备了形貌均一的AlPO₄-14分子筛, 分子筛的尺寸为15~18 mm; 然后采用晶种法即在反应凝胶中加入分子筛作为晶种进一步调控分子筛的大小, 使得AlPO₄-14分子筛的尺寸从15~18 mm减小到2~3 mm, 得到形貌均一的纯相片状晶体, 同时有效缩短了制备时间; 最后以多孔管状莫来石为支撑体, 采用二次生长法制备AlPO₄-14分子筛膜. 考察了2种不同大小的晶种对膜形貌和性能的影响, 发现以大尺寸的分子筛(15~18 mm)作为晶种制备的分子筛膜的分离层存在较多缺陷, 而采用小尺寸的晶种(2~3 mm)制备的膜层较均一致密. AlPO₄-14分子筛膜经高温脱除模板剂后仍然保持着纯相的AlPO₄-14晶型, 表明二次生长法促进了AlPO₄-14晶体在膜层中的生长且使其具有更高的结晶度和热稳定性. 在25 ℃, 100 kPa下, AlPO₄-14分子筛膜对H₂/CH₄, CO₂/CH₄和H₂/CF₄的理想分离因子分别为28, 40和1047, 且H₂和CO₂的渗透速率分别为6.3×10 ^-7和9×10 ^-7 mol·(m ²·s·Pa) ^-1; 对等摩尔CO₂/CH₄混合气体的分离因子为81.5, 且CO₂的渗透速率为8.8×10 ^-7 mol·(m ²·s·Pa) ^-1.     

间歇式水热合成制备丝光沸石膜及其异丙醇脱水应用

采用市售廉价大孔α-Al₂O₃管作为基质材料,通过热浸渍法在管外表面涂敷晶种,随后在无模板剂体系下,利用新型的间歇式水热合成法制备丝光沸石膜。对比了传统加热和间歇式加热对丝光沸石膜形貌、结构及渗透蒸发异丙醇脱水分离性能的差异。考察了合成液中Na₂O/SiO₂、SiO₂/Al₂O₃和NaF/SiO₂物质的量之比在间歇式水热合成下对丝光沸石膜的影响。研究结果表明,当合成液中Na₂O/SiO₂、SiO₂/Al₂O₃和NaF/SiO₂物质的量之比分别为0.24、16.7和0.25时,制备的丝光沸石膜渗透蒸发异丙醇脱水分离性能最佳,在75℃下,对异丙醇/水(9:1,w/w)的渗透通量达5.60 kg·m^-2·h^-1,水对异丙醇的分离因数大于10 00...     

MFI型分子筛膜的两段变温合成及对二甲苯异构体的分离性能

分别采用恒温和变温两种方法在氧化铝支撑体上原位制备了MFI型分子筛膜. 恒温法合成的MFI型分子筛膜晶体颗粒较大, 在高温脱除模板剂时会形成较大的缺陷, 没有对二甲苯/邻二甲苯(PX/OX)分离性能. 变温法合成的MFI型分子筛膜晶体在a, b方向尺寸较小, 在高温脱除模板时不会形成较大缺陷, 对PX/OX有良好的分离性能, 在300 ℃下, PX/OX分离因子高达42, PX的渗透性为9.57×10^-9 mol·m^-2·s^-1·Pa^-1. 采用低温臭氧脱除模板剂能够有效减小分子筛晶体热收缩产生的应力, 提高MFI型分子筛膜的分离性能. 两种方法合成的分子筛膜在低温臭氧的条件下脱除模板剂后, 都具有PX/OX分离性能, 其中变温法合成的分子筛膜PX/OX分离因子高达76, PX的渗透性为1.02×10^-8 mol·m^-2·s^-1·Pa^-1.     

g-C3N4/TiO2-PVDF光响应膜界面实现高效油水分离:不同暴露晶面诱导的渗透性和选择性差异及性能

油滴堵塞导致的膜污染问题限制了膜技术在油水分离中的应用,构建选择性分离油水混合液的功能界面是实现高效油水分离的重要途径.本文制备了Ti O₂(001)和(101)晶面暴露的g-C₃N₄/Ti O₂-PVDF(聚偏氟乙烯膜)光催化膜,研究了不同暴露晶面对油水分离效果的影响及作用过程.结果显示,光照射下,Ti O₂(001)晶面赋予了g-C₃N₄/Ti O₂(001)-PVDF膜优异的超亲水和水下超疏油特性,与Ti O₂(101)晶面暴露的膜相比,g-C₃N₄/Ti O₂(001)-PVDF膜具有更优异的油水分离性能.g-C₃N₄/Ti O₂(001)PVDF膜在可见光照射下,纯水通量达到2002.9 L·m^?2·h^?1,...     

十七氟癸基修饰的有机-无机杂化二氧化硅膜材料的制备及气体分离性能

以十七氟癸基三乙氧基硅烷(PFDTES)和1,2-双(三乙氧基硅基)乙烷(BTESE)为前驱体, 通过溶胶-凝胶法制备了十七氟癸基修饰的SiO₂溶胶, 采用浸渍提拉法在γ-Al₂O₃/α-Al₂O₃多孔陶瓷支撑体上涂膜, 然后在N₂气氛保护下烧结成完整无缺陷的有机-无机杂化SiO₂膜. 利用扫描电子显微镜对膜材料的形貌进行观察, 通过动态光散射技术对溶胶粒径及分布进行测试, 利用视频光学接触角测量仪、 红外光谱仪和热分析仪表征了十七氟癸基修饰对有机-无机杂化SiO₂膜疏水性的影响. 结果表明, 十七氟癸基已经成功修饰到SiO₂膜材料中, 且随着PFDTES加入量的增大, 溶胶粒径和膜材料对水的接触角不断增大. 当n(PFDTES): n(BTESE)=0.25: 1时, 溶胶粒径分布较窄, 平均粒径为3.69 nm, 膜材料对水的接触角为(112.0±0.4)º. 在修饰后的有机-无机杂化SiO₂膜中H₂的输运遵循微孔扩散机理, 在300℃时, H₂的渗透率达到5.99×10^-7 mol·m^-2·Pa^-1·s^-1, H₂/CO和H₂/CO₂的理想分离系数分别达到9.54和5.20, 均高于Knudsen扩散的理想分离因子, 表明膜材料具有良好的分子筛分效应.     

薄片状MFI晶体无凝胶蒸汽辅助晶化制备b轴取向沸石膜

采用新型薄片状MFI沸石晶体作为晶种,通过无凝胶蒸汽辅助晶化法(gel-less steam-assisted crystallization,GLSAC)在烧结氧化硅多孔载体上制备了致密平整、b轴取向的MFI沸石膜。考察了GLSAC中模板剂浓度、釜底水量、生长温度及时间对MFI沸石膜的影响。扫描电子显微镜和X射线衍射结果显示,适量的模板剂和釡底水量能抑制晶种的面外生长。成功制备了厚度750 nm、致密平整的MFI沸石膜。制备的对丁烷异构体气体分离测试表明,25℃时,等物质的量的丁烷异构体的分离因子(SF_A/B)可达36,对正丁烷的渗透速率为1.5×10^-7mol·m^-2·s^-1·Pa^-1。     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。     

Acid hydrolysis of carboxymethylcellulose of low degree of substitution

Cotton cellulose was swollen in a sodium hydroxide solution and carboxymethylated by a two-bath method for different periods of time for each process. The kinetics of acid hydrolysis and the crystallinity of the swollen and carboxymethylated samples were measured. The proportion of broken bonds, rate constants for hydrolysis, and permeability of cellulose to hydrolyzing agents were calculated. The susceptibility of glycosidic linkages to acid hydrolysis was improved by carboxymethylation more than by swelling in alkali. The increased accessibility of carboxymethylcellulose to acid was regarded as a consequence of increased intra-and intercrystalline swelling and of the glycosidic bonds' weakness caused by the electron-attracting carboxymethyl group on the C-6 position.     

氯氧化镁生成热的研究

用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

Synthesis of phenolic components of Grains of Paradise

Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.     

Estimation of Kinetic Parameters of Thermal Oxidation of Ilmenite

The aim of the presented work was the investigation of thermal oxidation of ilmenite in static air atmosphere. The investigations were carried out by use of a derivatograph (MOM, Hungary). The changes of crystallographic structure of investigated samples were identified by X-ray diffractometry on Philips PW-1710 diffractometer. In temperature above 500°C appears structure of hematite Fe₂O₃. On the basis of the thermogravimetric measurements, the contracting area and contracting volume models were found as the best fitting experimental data. This revised version was published online in August 2006 with corrections to the Cover Date.     

Mechanism of action of base-catalyzed oxygenation of phenol derivatives

Cyclopropyl derivative of 2,6-di-tert-butylphenol is synthesized as a probe to investigate the mechanism of base-catalyzed autooxidation of phenol derivatives. Our study indicates that one electron reduction of molecular oxygen from phenolate gives phenoxyl radical 3, a key intermediate of autooxidation. The coupling of phenoxyl radical and superoxide radical gives peroxylate anion 4 and produces the final epoxy alcohol adduct 6.     

化学计量中不确定度评定研究进展

测量不确定度是表征合理地赋予被测量之值的分散性的参数。本文针对化学计量不确定度评定基础模型仅适用于线性模型、概率分布为正态分布或缩放位移t分布等局限,介绍了近年来不确定度评定的研究热点:蒙特卡罗方法(Monte Carlo Method,MCM),不确定度评定的来源、评定概念、评估方法及其发展过程,扩大了测量不确定度评定与表示的适用范围。     

微量钙的测定方法研究进展

介绍了1995-2006年期间测定微量和痕量钙的方法,如电感耦合等离子体-原子发射光谱法、原子吸收光谱法以及离子色谱法等的工作原理和特点,并说明了其测定微量钙的应用领域。并对微量钙的测定技术进行了展望(引用文献55篇)。