气体吸附法测定低比表面积氧化铝粉体的比表面积

采用气体吸附法原理,以低比表面积氧化铝粉体标准物质为例,利用美国麦克仪器公司的ASAP2020比表面积和孔隙度分析仪测定其比表面积,通过改变测试条件分析各项参数值对测定结果的影响。结果表明:吸附系统"死体积"、样品用量和脱气条件等对测定结果都有比较明显的影响;对于低比表面积氧化铝粉体的理想测定条件为脱附温度250℃,脱附时间2h,样品用量2.5~3g。试验所得结果可为低比表面积粉体的比表面积准确测定提供参考。     

高比表面积蜂窝状活性炭对CO2的吸脱附行为

以比表面积为2621m2/g的超高比表面积活性炭为原料,酚醛树脂为粘结剂,制得比表面积为1887m2/g的蜂窝状活性炭,并考察了其对CO2的吸脱附性能.研究结果表明,在25℃/常压下,该蜂窝状活性炭对CO2的饱和吸附量为2.15mmol/g,对浓度为15％的CO2的平衡吸附量为0.96mmol/g;当采用抽真空脱附时,...     

椰壳类活性炭孔隙结构对苯并噻吩脱附活化能的影响

主要研究活性炭孔隙结构对苯并噻吩脱附活化能及吸附性能的影响.使用ASAP 2010测定了3种椰壳制活性炭SY-6、SY-13和SY-19的BET比表面及其孔隙结构,采用程序升温脱附技术(TPD)测定了苯并噻吩在3种活性炭上的脱附活化能,用静态吸附法进行了苯并噻吩在不同活性炭上的吸附等温线,并讨论了活性炭孔隙结构对苯并噻吩脱附活化能及吸附性能的影响.结果表明,3种活性炭SY-6、SY-13和SY-19的比表面积分别为1106、1070和689m2/g,其平均孔径分别为1.96、2.58和2.16nm.苯并噻吩在SY-6、SY-19和SY-13活性炭上的脱附活化能依次为58.84、53.02和42.57kJ/mol,3种活性炭对苯并噻吩吸附容量的大小依次为SY-6＞SY-19＞SY-13.活性炭平均孔径越小,其表面对苯并噻吩的作用力越大,苯并噻吩在其表面上的脱附活化能越大.Freundlich模型能够较好的来描述苯并噻吩在活性炭上的吸附.     

介孔二氧化铈的制备、表征以及对CO的氧化性能研究

以无机盐硝酸铈和柠檬酸为原料,CTAB(十六烷基三甲基溴化铵)为模板剂,采用水热法制备了大比表面积的介孔CeO2,结合X射线粉末衍射(XRD)、N2吸附与脱附、H2程序升温还原(H2-TPR)和CO2程序升温脱附(CO2-TPD)等表征手段研究了CTAB加入及焙烧温度对介孔CeO2晶型结构和比表面积的影响,并对CO氧化催化机理进行了初步探讨。结果表明:前驱体与焙烧样品都具有晶型较好的CeO2立方萤石晶相结构和较大的比表面积,CTAB的加入不仅增大了样品的比表面积和孔容,而且在一定程度上提高了样品的结晶度;与其他样品相比,加入CTAB焙烧后的样品具有较好的催化效果。     

介孔铝酸钴的溶胶－凝胶法合成与表征

采用嵌段聚合物P123为表面活性剂，以氯化铝和氯化钴为无机先驱物，采用溶胶－凝胶法合成介孔铝酸钴纳米粒子。X射线衍射（XRD）表明样品具有单一的尖晶石型结构，利用氮气吸附－脱附比表面测定仪测得不同焙烧温度样品的比表面积，发现700℃焙样品比表面积最大，其比表面积为59．3E／g，孔径为10．8nm。紫外可见光谱仪测示表...     

镍纳米粉的比表面积和孔结构研究

采用阳极弧放电等离子体方法制备了高纯镍纳米粉,利用X射线衍射(XBD)、透射电子显微镜(TEM)对粉末的形貌、晶体结构、粒度进行了表征。样品的N_2的吸附-脱附等温线采用静态表面吸附仪在液氮温度下(78 K)在气体饱和蒸气压力范围内测试。依据BJH理论模型计算探讨了样品的累积孔表面积、累积孔体积、孔径及其BJH脱附分布等性能。用图解法由等温吸附直线求出单层吸附量,利用BET吸附公式计算出样品的比表面积。结果表明,镍纳米粉的比表面积为14.23 m~2/g,粒径为46 nm。     

高比表面积多孔炭质材料的孔结构特性及对苯酚的吸附

将中草药药渣微波干燥后经碳化、KOH活化制备出具有较高比表面积的多孔炭质材料。采用比表面积及孔隙分析仪测定其N_2吸附脱附等温线;采用扫描电子显微镜、X射线衍射分析仪对介孔材料表面显微结构、及物相变化进行了表征,并分析了多孔炭材料对苯酚的吸附性能。研究结果表明,当炭碱质量比1∶4时,制备的改性多孔炭材料具有丰富的多孔结构,其比表面积达2079.25m~2,介孔率达到79.10%;多孔炭材料对苯酚的饱和吸附量达到187.5mg/g。苯酚在多孔炭材料上的吸附行为符合Langmuir吸附模型。     

沥青基球形活性炭对CO2的吸脱附行为研究

考察了沥青基球形活性炭(PSAC)的孔结构与CO2吸附容量间的内在关系及其脱附性能.采用N2吸附法分析PSAC的孔结构,由穿透曲线测试其对CO2的平衡吸附量.实验结果表明:在CO2/N2混合气氛下,活性炭对CO2的吸附容量与孔径小于1nm的微孔比表面积呈线性关系;当PSAC担载5%的三聚氰胺后,对CO2(15%)的平衡吸附量由0.91mmol/g增加到1.15mmol/g,提高了26.3%;采用抽真空脱附时,循环脱附效率为74.6%,而电解吸-抽真空耦合脱附工艺可使CO2的循环脱附效率接近100%.     

石墨纤维的比表面积与孔隙结构的测定与分析

为了定量地描述和分析石墨纤维的比表面积和孔隙结构,采用低温氮吸附法测定石墨纤维在液氮温度和不同压力条件下的氮气吸附-脱附等温曲线.研究表明石墨纤维属于微孔材料,含有大量的微孔和极少量的介孔;石墨纤维的BET比表面积、总孔体积和平均孔径分别为541.00m2/g、0.2436cm3/g、1.8010nm,其微孔的比表面积...     

结构助剂对高比表面碳化硅结构的影响

以糠醇为碳源,正硅酸乙酯为硅源,硝酸钴为催化剂,含氢硅油为结构助剂,通过溶胶凝胶和碳热还原的方法制备出高比表面积多孔碳化硅,采用XRD、SEM、TEM、HRTEM和低温氮吸附-脱附对所制备的样品进行表征.结果表明,添加了结构助剂得到的碳化硅的比表面积可达125-167m2· g-1,其用量对碳化硅的比表面积和孔容有重要...     

Preparation of high-purity tantalum powders by sodium-thermal reduction

This paper examines the possibility of preparing high-purity sodium-reduced tantalum powders with a large specific surface area. We demonstrate that such powders have a larger specific surface area when prepared using potassium heptafluorotantalate based melts containing tantalum oxyfluoride compounds. The purity and specific surface area of powders thus prepared are suitable for the development of capacitor powders with a specific capacity of up to 100000 μFV/g.     

MEASUREMENT OF THE SPECIFIC SURFACE AREA OF POWDERS BY THIN LAYER WICKING

The specific surface areas (A) of different clay mineral powders were measured by both the BET method and by thin layer wicking. The values of A for the BET and the wicking experiments coincided within a few percent. Thus, the simple and inexpensive thin layer wicking approach may well suffice to obtain reliable specific surface area values for most powders. From the wicking data it is also possible to obtain a rough estimate of the average particle size.     

矿物颗粒表面纳米化修饰及其在PP复合材料中的应用

通过化学方法成功地实现了矿物粉体在Ca (OH)₂-H₂O-CO₂ 体系中的表面纳米化修饰, 即在微米级重质碳酸钙、硅灰石粉体表面形核生成粒径均匀的纳米碳酸钙颗粒层。研究表明, 表面纳米化修饰后的矿物粉体表面的粗糙度大大增加, 尖锐的棱角得以钝化, 纳米化修饰后矿物粉体比表面积比原来提高至少200 %以上。将经表面纳米化修饰后的硅灰石粉体在聚丙烯(PP) 中填充应用, 较未经表面纳米化修饰的硅灰石粉体填料, 其抗冲击强度提高65 %以上, 延伸率提高200 %以上。     

MEASUREMENT OF THE SPECIFIC SURFACE AREA OF POWDERS BY THIN LAYER WICKING

ABSTRACT

The specific surface areas (A) of different clay mineral powders were measured by both the BET method and by thin layer wicking. The values of A for the BET and the wicking experiments coincided within a few percent. Thus, the simple and inexpensive thin layer wicking approach may well suffice to obtain reliable specific surface area values for most powders. From the wicking data it is also possible to obtain a rough estimate of the average particle size.     

Specific surface area determination methods, devices, and results for diamond powders

A review of available methods for specific surface area determination for various dispersed materials is presented. Fundamental differences between the currently used devices and procedures of the analysis of external and total specific surface, including those applicable to powders of superhard materials and refractory compounds, are discussed. Some data on specific surface of synthetic diamond grits, micron powders, and submicron powders are provided for practical applications.     

The preparation of tungsten oxide powders with high specific surface areas

Tungsten oxide powders with high specific surface areas (50 m²g^–1) are prepared by using a variation on the hot kerosene drying technique. It is also shown that the use of a water in oil emulsion in the hot kerosene drying technique has no effect on the specific surface areas of the resultant powders. The reason for the absence of any effect is explained. The difference between the powders prepared by the hot kerosene drying technique and the variation of this, is the high specific surface area due to the porous structure of the powders prepared by the latter method.     

Preparation of nano-silver iodide powders and their efficiency as ice-nucleating agent in weather modification

Nano-meter-sized silver iodide (n-AgI) powders were prepared by precipitation method at room temperature. The size, structure and specific surface area of the n-AgI powders were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscope and Brunner–Emmett–Teller, respectively. The n-AgI powders obtained have an average particle size of ～90 nm, similar surface lattice structure with ice crystal (H₂O) and larger specific surface area than conventional micro-meter-sized silver iodide (m-AgI) powders. The cloud chamber experiment revealed that the n-AgI powders exhibit higher ice nucleation efficiency and higher threshold temperature value than conventional m-AgI powders.     

Specific surface area studies of shock-modified inorganic powders

Modification of inorganic powders with high-pressure shock-wave loading is of interest for shock-activated sintering, material synthesis, shock-enhanced catalytic activity, dynamic compaction, and shock-enhanced solid-state reactivity. The specific surface area of shock-modified powders is a direct quantitative measure of powder morphology changes, yet few studies have been carried out on powders subjected to controlled shock-loading conditions. In the present work aluminium oxide, zinc oxide, aluminium nitride, titanium carbide and titanium diboride powder compacts were subjected to controlled shock-loading to peak pressures of from 4 to 27 GPa at various starting densities, and characterized with specific surface area measurements by the BET (gas adsorption) method. Low-temperature cyclical thermal pretreatment and outgassing pretreatment of the shock powders at 250° C were employed; the former improves the reliability of the BET measurements, and makes the surfaces of the shock-modified powders more chemically active than those of the starting powders. Each powder shows a somewhat different response to shock-loading, ranging from a decrease in specific surface by a factor of six for zinc oxide to a 200% increase for titanium diboride. Shock-induced changes in specific surface show four characteristic behaviours as shock pressure is increased. Well-understood and controllable shock-loading conditions are found to be essential to shock-modification studies. An update on earlier measurements on rutile, zirconia and silicon nitride is also reported.     

四氯化钛水解法制备二氧化钛纳米晶的影响因素

研究了四氯化钛水解法制备的二氧化钛纳米晶工艺中水解８温度和硫酸根离子对粉体性能的影响室温下的水解产物为无定形结构,这种粉体有着很大的比表面积,其孔为介孔尺度;添加少量的硫酸根离子使粉体的孔径在２～５ｎｍ,最可几孔径为３．８ｎｍ,提高水解温度能得到金红石与锐钛矿相的混晶,同样的水解温度下,添加少量的硫酸根离子则为纯锐钛矿相,用到金红石与锐钛矿相的混晶,同样的水解温度下,添加少量的硫酸根离子则为纯锐钛     

Properties of Nitrides Prepared by the Ammonolysis of Magnesiothermic Niobium Powders

We have studied the effects of the specific surface area of mesoporous magnesiothermic niobium powders and ammonolysis conditions on characteristics of the reaction products. Ammonolysis was carried out in the temperature range 400–800°C using powders with specific surface areas of 18, 83, and 123 m²/g. The results demonstrate that the ammonolysis of the powders with specific surface areas of 83 and 123 m²/g first leads to the formation of the NbON oxynitride, which then converts into NbN with a face-centered cubic lattice at a temperature of 700°C. The NbN nitride obtained by the ammonolysis of the powder with a specific surface area of 18 m²/g has a hexagonal close-packed structure.