超级活性炭的制备及其储氢性能初步研究

以高硫焦为原料,通过L9(34)正交设计,制备出一系列超高比表面积活性炭.系统地测定了氢在93K～293K、0MPa～7MPa范围内,在SBET为3886m2/g的超级活性炭上的一组吸附等温线.实验结果表明 ,吸附等温线具有Ⅰ-型等温线特征且储氢效果良好,其中在293K/5MPa、93K/6MP a的条件下,储氢质量分数分别达1.9W/%、9.8W/ %.一定条件下的等量吸附线研究表明,氢在超级活性炭上的等量吸附热较小,且主要集中在4.8kJ*mol-1～6.5kJ·     

吸附剂吸附热的计算分析

对分子筛和两种活性炭吸附剂进行了吸附等温线测试,并利用实验结果进行吸附热的计算,计算结果显示:CO的等量吸附热随着吸附量的增加逐渐减小,通过不同温度下的吸附等温线计算的等量吸附热相差不大;CO在分子筛上的等量吸附热大于在活性炭上的等量吸附热,且对于两种不同的活性炭对应的等量吸附热有较大的差异;不同的气体在同一种吸附剂上的吸附热大时,其对应的吸附量不一定大;实验结果显示了吸附过程的复杂性。     

金属有机骨架材料MIL-96的制备及其对萘的吸附性能研究

通过水热法合成铝基-金属有机骨架(MOFs)MIL-96材料,并将其作为吸附剂用于脱除水溶液中的萘。采用扫描电子显微镜、X射线衍射仪和N_2吸附-脱附等方法对材料进行表征。通过考察吸附动力学、吸附等温线以及热力学特征研究了MIL-96材料的吸附性能。研究结果表明:在温度298K、MIL-96材料用量为0.5g/L时,对萘的最大去除率达到约98%;MIL-96对萘的吸附特征符合准二级吸附动力学模型,Temkin和D-R等温吸附模型对萘吸附过程的描述比其他模型准确;Temkin等温吸附方程中吸附热相关系数表明,MIL-96吸附水溶液中萘的过程为吸热过程,热力学参数中正的标准焓变(ΔH~o)值也说明该吸附过程为吸热过程。     

Ag掺杂改性MIL-101的制备及其对碘离子的吸附性能

为了提高金属有机骨架多孔材料MIL-101对水体中碘离子的吸附性能,通过水热合成法制得Ag掺杂改性MIL-101材料,利用扫描电子显微镜、X射线衍射、比表面积及孔径分析、激光衍射粒度分析等技术手段对材料进行表征,并考察多种参数对吸附效果的影响。结果表明:纳米Ag主要存在于基体材料MIL-101的晶格中,对材料的晶体结构无显著破坏;N,N-二甲基甲酰胺(DMF)加乙醇的后处理方法能有效提高材料的吸附性能;改性后的材料表现出快速、高效的吸附性能;在痕量碘离子环境下,Ag掺杂质量分数为2%的改性MIL-101的饱和吸附量可达23 mg/g,吸附效率达到93%以上;在高浓度环境下,样品吸附效率随着Ag掺杂量的增加而提高。     

高邻位热固性酚醛基纳米活性炭纤维膜的制备及吸附性能

以合成的高邻位热塑性酚醛为模板,通过与甲醛的加成反应制备了高邻位热固性酚醛树脂,经溶液静电纺丝、盐酸溶液固化获得了纳米酚醛纤维,最终利用KOH活化获得了高邻位热固性酚醛基纳米活性炭纤维。利用红外光谱、X射线衍射、热重分析和扫描电镜分析了制备物的结构、性能变化,并观察了纳米纤维的表面形貌;通过比表面积和亚甲基蓝(MB)/碘吸附分析了纳米活性炭纤维的孔结构和吸附性能,获得了比表面2606 m~2/g、MB吸附量1643.0 mg/g、碘吸附量2731.1 mg/g的高邻位热固性酚醛基纳米活性炭纤维,实现了低污染、高活性纳米炭纤维的制备。     

沥青基活性炭纤维的微孔性及其对NO,SO2和NH3的吸附特性

通过对新开发的沥青基活性炭纤维(ACF)在77K温度下对氮的吸附和303K温度下对苯的吸附研究,考察其微孔性。沥青基ACF具有均匀的微孔,孔径为0.9-1nm,孔体积为0.45-1.0ml/g。也考察了在303K温度下对NO、SO_2和NH_3的吸附行为。不仅对氮和苯而且对NO、SO_2和NH_3的吸附等温线进行了DR关联,作出关联图并讨论了微孔填充。微孔填充度按NO、NH_3、SO_2次序增大。每种气体微孔填充度和等量吸附热随这些被吸附气体的范德华(Van der Waals)力的增加而增加。     

竹质中孔活性炭的制备及其吸附性能研究

以毛竹废料为原料通过磷酸活化法制备了具有较高比表面积并含有大量中孔的活性炭.讨论了磷酸浓度、浸渍温度、浸渍时间、活化温度及活化时间对活性炭性质的影响.在以80%磷酸于80℃下浸渍原料9d,500℃下活化4h的条件下所得活性炭的中孔体积最大,其数值为0.67cm3/g,比表面积为1567m2/g,中孔比例达47.18%.实验测定了CH4,N2,O2和CO2在该活性炭上的298K吸附等温线.实验结果表明,该活性炭对二氧化碳的吸附能力明显优于CH4、O2和N2,是适用于CO2/N2、CO2/O2、CO2/空气气体混合物中CO2吸附分离的优良吸附剂.     

高比表面积PAN-ACF的吸附与孔结构解析

以KOH为活化剂制备了比表面积大于2000m^2/g的高比表面积PAN基活性炭毡（ACF）,以液氦为吸附介质在77．4K测试PAN－ACF吸附等温线,并对其孔结构进行了表征。采用BET法计算比表面积,t-plot法,Horvath-Kawazoe,Dubinin-Radushkevich方程以及密度函数理论（DFT0表征孔结构。研究表明即使比表面积超过3000m^2/g时,PAN－ACF的孔分布仍然很窄,并且含有大量的分子筛型孔,以金子克美等人提出多段吸附机理为依据,采用DR方程对PAN－ACF三段吸附过程所对应的E^0,x进行了计算。结果认为低压段的负偏离在一定程度上是由于吸附较强的微孔与表面官能团共同作用的结果,并非完全由于活化扩散引起,以上分析方法的表征结果具有较好的一致性,为PAN－ACF的吸附性能与孔结构提供了准确的信息。     

氟化活性炭纤维对极性分子的吸附

将活性炭纤维（ACF）与氟气反应制备出氟化活性炭纤维（FACF），根据将FACF与参照试样XPS的对比，碳原子是以sp^3杂化轨道同氟原子形成共健键。αs图分析氮吸附等温线的线果表明，ACF氟化后其比表面积和微孔容积都显著降低，微孔宽度基本不变，ACF的水吸附等温线呈V型，而FACF对水的吸附量极小；FACF的微孔表面具有完美的憎水性和高稳定性，乙醇和甲醇在ACF上的吸附等温线是Ⅰ型，在FACF上接近于Ⅰ型，但吸附量显著降低。     

微-介孔分级结构MIL-101(Cr)的制备及其性能

为简化合成工艺、降低样品损耗,以丙酸作为添加剂,通过改变丙酸与九水硝酸铬浓度比,合成含有微-介孔分级结构的MIL-101(Cr)。利用X射线衍射仪、全自动比表面及孔隙度分析仪及扫描电子显微镜等表征手段对不同浓度比的MIL-101(Cr)的粒径、BET比表面积、孔体积、N_2吸附性能和微观结构进行研究。结果表明:选择适量的丙酸可以合成含有微-介孔分级结构的MIL-101(Cr),其具有更强的吸附性能。在该反应体系中,丙酸的浓度可以改变MIL-101(Cr)的结构,且合成方式简易方便,为拓展MIL-101(Cr)的应用提供可行的方案。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。