一种高纯度大孔硅胶的制备工艺

以硅酸盐、无机酸为原料,经凝胶、老化、酸化、水洗、除杂、干燥工序后得到高纯度大孔硅胶,用比表面空隙仪对样品的物性参数进行了分析,用X-荧光分析仪对样品中的SiO2和杂质含量进行了测定.结果表明,将所选用的除杂剂加入常规工艺制得的硅胶滤饼中,在水浴温度为60℃、搅拌时间为1 h的条件下,可以得到孔容为1.5～2.0 mL...     

胺类硅胶材料的合成及应用

胺类硅胶材料由于具有强吸附性能已经成为人们研究的热门课题,已应用于污水处理、生物医药等很多领域.胺类硅胶材料合成方法主要有包覆法、硅烷偶联剂法、溶胶-凝胶法和化学改性法.本文简单介绍了硅烷偶联剂法和溶胶-凝胶法合成胺类硅胶材料及其在生活中的应用.     

二氧化硅气凝胶的制备工艺与应用

三维纳米孔隙结构的二氧化硅气凝胶具有孔隙率高、密度低、比表面积大等基本特征,这些优异的特性使二氧化硅气凝胶在许多领域得到广泛研究和应用。二氧化硅气凝胶一般通过溶胶-凝胶过程、老化、干燥处理得到。主要总结了二氧化硅气凝胶的制备过程及机理,介绍二氧化硅气凝胶的相关领域的应用,并对二氧化硅气凝胶材料的发展前景进行了展望。     

硅胶的发展现状及应用

硅胶的化学性质稳定、吸附性能高、热稳定性好、较高的机械强度,是一种高活性多孔材料。硅胶生产方法很多,以硅酸钠和无机酸为原料的溶胶-凝胶法应用最为广泛。硅胶改性包括硅胶扩孔和硅胶负载,改性后的硅胶,性能优良,应用更为广泛。硅胶负载金属镍是一种很好的脱除油品中氮化物的吸附剂,金属负载量、吸附温度、吸附时间不同,硅胶吸附脱氮的效果也不同。目前,硅胶已经广泛应用到各行各业,硅胶在石油化工、医药、食品、油墨、农业的应用发展迅速。     

纳米二氧化硅制备工艺的研究

以TEOS(正硅酸乙酯)为前驱体、氨水为催化剂和无水乙醇为溶剂,采用溶胶-凝胶法制备了纳米二氧化硅。利用傅里叶变换红外光谱(FT-IR)仪和纳米激光粒度分布仪对纳米二氧化硅的结构、粒径及其分布进行了表征,并着重探讨了反应温度、催化剂浓度和反应时间等对纳米二氧化硅粒径的影响。研究结果表明:当反应温度为60℃、催化剂浓度为0.82 mol/L和反应时间为3~4 h时,制得的纳米二氧化硅平均粒径为300 nm左右。     

硅胶载体的制备

一种硅胶载体的制备方法，其特征在于在硅凝胶的制备上，采用了以部分稀硅酸盐溶液为母液，稀硅酸盐与元机酸同时加入的方式。所得的硅胶作为茂金属催化剂的载体，用于烯烃聚合反应。     

硅胶载体的制备

一种硅胶载体的制备方法，其特征在于在硅凝胶的制备上，采用了以部分稀硅酸盐溶液为母液，稀硅酸盐与元机酸同时加入的方式。所得的硅胶作为茂金属催化剂的载体，用于烯烃聚合反应。     

影响硅胶质量因素的探索

分析影响硅胶质量的原因,提出提高硅胶质量的具体措施。     

大孔硅胶烷基键合固定相的制备

采用大孔硅胶和一氯硅烷制备了几种用于蛋白质分离的大孔硅胶短链烷基键合固定相。     

Effect of preparation pH on properties of silica gel

Silica gels were obtained by drying the silica hydrogels formed at pH values between 1 and 4 at 100°C. The bulk density of the 2–3 mm diameter fraction decreased from 0·62 g cm^?3 to 0·20 g cm^?3 as the preparation pH increased from pH 3 to pH 3·65. The apparent density of silica gels was between 1·43 and 1·95 g cm^?3. Isotherms for the adsorption of water vapour on samples prepared at different pH values showed hysteresis in all cases. Thermogravimetry analysis showed that the amount of bound water was in the range of 4·4 to 5·5% on a dry weight basis. Specific heats were determined by a differential scanning calorimetry method using a sapphire standard and were between 0·82 and 0·97 J g^?1 K¹.     

耐水硅胶材料制备工艺条件优化实验研究

运用正交实验设计及方差分析方法,以耐水硅胶材料的比表面积和孔容为考察指标,研究了在硅胶制备过程中硫酸铝溶液质量分数、原料硫酸与硫酸铝物质的量比等因素对实验结果影响的显著性。结果表明,硫酸铝溶液质量分数及原料硫酸与硫酸铝物质的量比对实验结果影响最为显著。最优工艺参数：硫酸铝溶液质量分数为6%,原料硫酸与硫酸铝物质的量比为2∶1,酸泡过程硫酸与硫酸铝物质的量比为6∶1,碱泡过程中稀氨水质量分数为0.1%,老化时间为1.5 h。在最优工艺条件下,可得到比表面积不低于300  m²/g、孔容不低于0.7 mL/g的具有良好耐水性的吸附分离材料。     

大孔氧化铝载体制备条件的研究

本文以拟薄水铝石为原料,槽法炭黑为扩孔剂制备了大孔氧化铝载体,并对制备条件进行了研究,找到了制备条件对载体孔结构及强度的影响规律。     

萃取条件对UHMWPE冻胶纤维结构与性能的影响

以二甲苯为萃取剂,对超高相对分子质量聚乙烯(UHMWPE)冻胶纤维中的溶剂进行萃取,研究了不同萃取条件下UHMWPE冻胶纤维的结构与性能。结果表明,UHMWPE冻胶纤维的最佳萃取条件为萃取时间5 min,萃取温度50℃。随着萃取温度的升高,UHMWPE冻胶纤维的强度和模量增大,萃取温度50℃时,其结晶度最大。经萃取干燥的UHMWPE冻胶纤维截面具有微孔的网状结构。     

A multilayer thickness relationship applicable to pore size analysis of silica gel

A single multilayer curve was arrived at for the adsorption of nitrogen on silica gel. An empirical equation, fitted to the curve, proved to be suitable in the pore size analysis of 26 samples of silica gels; specific surface areas from 178 to 814 m²/g, mean pore radii of 12.6 up to 74.4 Å, and total pore volumes of 0.5126 to 0.8613 ml/g. Cumulative surface areas were evaluated by the procedures of BJH, Cranston and Inkley, and Roberts; the values obtained were generally in agreement with specific surface areas obtained by the BET equation, S_BET, within ± 5%. The empirical equation is completely independent of the structural characteristics of the material. Comparison was made with data obtained by the use of the method of Mingle and Smith, for evaluating multilayer thickness, and which depends on both mean pore radius, and BET-C value, for each single solid. Good concordance appears between the cumulative surface areas, as well as the pore size distributions, calculated by employing either this latter t-estimate or the empirical equation.     

不同孔径硅胶上异丁烷脱氢性能研究

采用Cr₂O₃为活性组分,K₂O为助催化剂,以不同孔径硅胶为载体,制备异丁烷脱氢催化剂,在连续微反-色谱装置上对催化剂的反应性能进行考察,结果表明,A型硅胶与B和C型硅胶相比具有更好的脱氢性能,在负载Cr₂O₃质量分数为20%和K₂O质量分数为2%时,600 ℃条件下,异丁烷转化率为24.00%,异丁烯选择性为80.94%,SEM分析表明,高温下催化剂A和B不够稳定,催化剂C的稳定性较好。     

粗孔微球硅胶负载氢氧化锆对磷酸根吸附性能

以粗孔微球硅胶为载体,采用浸渍法负载ZrOCl2,然后用氨水将ZrOCl2转化为ZrO(OH)2,得到ZrO(OH)2/SiO2吸附剂,研究其对水溶液中磷酸盐的吸附。单独使用粗孔微球硅胶作为吸附剂时对磷酸根没有任何吸附作用。单独使用ZrO(OH)2·2.6H2O(用量0.1g)作为吸附剂时60min吸附量为120.4mg PO43-/g,以纯ZrO(OH)2计的吸附量为160.3mg PO43-/g,当ZrO(OH)2/SiO2负载量为10%时,用量为0.5g,在相同条件下吸附量为36.4mg PO43-/g,以纯ZrO(OH)2计的吸附量为364.3mg PO43-/g。吸附动学实验表明吸附过程符合准二级动力学模型。     

Effect of preparation methods on thermal properties of poly(acrylic acid)/silica composites

Poly(acrylic acid)-silica composites have been prepared by two different methods and thermally characterized. The glass transition temperature (T_g) of the PAA-SiO₂ system prepared by mixture method was found to be 120°C irrespective of the type and amounts of silica involved in this work. However, the T_g varied between 132°C and 113°C in the systems prepared by polymerization reaction depending upon the type of silica and percentage conversion. The composites prepared by mixture and polymerization method have been investigated by using thermogravimetry (TGA) to follow the kinetics of anhydride formation and thermal degradation reactions. The activation energy of thermal anhydride formation and thermal degradation reaction was not found to change very much with ratio of PAA-SiO₂ when the composites were prepared by simple mixing. For the composites prepared by polymerization method the activation energy of anhydride formation and thermal degradation reaction were observed to change with percentage conversion. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 891–895, 1998     

Effect of gel electrolytes containing silica nanoparticles on aluminum corrosion

We have investigated corrosion of aluminum current collectors in electrolytes containing LiTFSI salt by chronopotentiometry, cyclic voltammetery, chronoamperometry, electrochemical impedance spectroscopy, and optical microscopy. Open-circuit potentials for cells with gel electrolytes containing silica nanoparticles are relatively stable in comparison to the corresponding baseline liquid, which suggests that the Al/electrolyte interface is more stable in presence of silica nanoparticles. Cyclic voltammetery and chronoamperometry data show that the current density for Li/electrolyte/Al cells with gel electrolytes containing fumed silica was less than that for baseline liquid electrolyte. The Nyquist plot for liquid electrolyte after chronoamperometry is semicircular-like, that is a corrosion reaction occurred. After cell disassembly, black particulates are evident and pits are observed on the aluminum foil. In comparison, no corrosion products are observed for cells containing gel electrolytes, and the Nyquist plots indicate that corrosion does not occur appreciably. Gel electrolytes produce impedance spectra with a large phase lag over a wide frequency range, which is not observed for the baseline liquid electrolyte. These phenomena may be interpreted as a good film-coating behavior associated with gel electrolytes, which results in a lower aluminum corrosion rate.