共查询到20条相似文献,搜索用时 593 毫秒
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本文描述了大孔径涂敷柱LBC柱的制备及其对水中痕量有机物的吸附富集技术的研究,LBC柱是一种涂有固定液SE-30的大孔径金属柱,用以直接吸附富集水中痕量有机物,然后热脱附到GDX-502预柱上,用CS_2洗脱并浓缩后注入气相色谱仪进行分析测定。本文还讨论了溶液浓度、柱长度、过柱速度、徐膜厚度对LBC柱吸附富集效率的影响及其本方法的重现性。相对标准偏差小于7%。 相似文献
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酸处理对β沸石结构和酸性的影响 总被引:20,自引:0,他引:20
考察了酸处理对β沸石的酸性的影响,发现β沸石的骨架虽易脱铝,但能抗5mol/LHCl,d 5mol/LHCl中,β沸石的脱铝程度可达80.0%以上,β-沸石的孔容影响不大,NH3-TPO及Py-Ir结果表明,β沸石经酸处理后,其强度增加,在樱椋粒欤剑常福秆飞洗锏阶钋浚砻嫠嵋裕趟嵛鳎宜妫樱椋粒毂鹊脑黾佣銮俊? 相似文献
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以可控孔径玻璃为基质的疏水作用固定相的研制 总被引:1,自引:0,他引:1
以不同分子量的聚乙二醇(PEG 400,600,800,1000和2000)为配基,发展了一类以可控孔径玻璃(CPG)为基质的疏水作用色谱固定相,研究了其分离生物高分子的色谱条件,这类固定相可以以很高的活性回收率使蛋白质得到满意的分离。 相似文献
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W.Richard Bowen Nidal Hilal Robert W. Lovitt Peter M. Williams 《Journal of colloid and interface science》1996,180(2):350
Noncontact atomic force microscopy (AFM) has been used to investigate the surface pore structure of eight Diaflo ultrafiltration membranes covering a range of nominal molecular weight cutoff (MWCO) from 3000 to 300,000 and manufactured from three different polymer types. Excellent high resolution images were obtained. Analysis of the pore images gave quantitative information on the surface pore structure, in particular the pore size distribution and surface roughness. Such data is compared to that obtained by other techniques. Noncontact AFM is a facile and informative means of studying the surface structure of porous materials such as synthetic membranes. 相似文献
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RongChunXIONG XiaoDongLEI GangWEI 《中国化学快报》2003,14(9):969-972
The preparation process of γ-A12O3 nanofiltration membranes were studied by N2 absorption and desorption test and retention rate vs thickness gradient curve method. It was found that template and thermal treatment were key factors for controlling pore size and its distribution.Under the optimized experimental conditions, the BJH (Barret-Jovner-Halenda) desorotion average pore diameter, BJH desorption cumulative volume of pores and BET (Brunauer-Emmett-Teller)surface area of obtained membranes were about 3.9 nm, 0.33 cm3/g and 245 m2/g respectively, the pore size distribution was very narrow. Pore size decreased with the increasing of thickness and no evident change after the dense top layer was formed. The optimum thickness can be controlled by retention rate vs thickness gradient curve method. 相似文献
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采用pH摆动法,以硫酸铝为铝源,以氢氧化钠为碱沉淀剂,考察了添加SiO2对沉淀氧化铝物性的影响.通过孔结构分析、粒度测定和电镜观察等证实,加入少量SiO2可使沉淀粒子分散、变小,颗粒相对均匀,从而提高了氧化铝的比表面积和孔集中的程度.当加入2.5%的SiO时,pH仅摆动2次,即可使氧化铝粉体的孔体积高达1.2ml/g,比表面积达380m2/g.这类氧化铝的孔结构适宜,粒子小,易直接成型为孔径集中和耐压强度好的载体,故用于重油高压加氢脱氮反应具有较好的性能.沉淀时酸侧pH值降低,尽管沉淀氧化铝的孔径向较小的方面集中,但此时沉淀粒子呈紧密堆积,颗粒变大,比表面积下降,氧化铝沉淀粒子的结构发生改变.不同结构的氧化铝表现出不同的催化活性. 相似文献
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大孔树脂孔结构的测定 总被引:11,自引:0,他引:11
介绍了大孔树脂比表面积,孔容,平均孔径及孔径分布等孔结构参数的测定方法,对各参数的不同测定方法进行了分析,比较。通过作者的工作,对大孔树脂的孔结构测定及测定中需要注意的问题进行了讨论,对各种方法的特点进行了总结。 相似文献
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Effect of Structure and Pore Size of Mesoporous Molecular Sieve Materials on the Growth of Carbon Nanotubes 总被引:1,自引:0,他引:1
N. He C. Yang Q. Dai Y. Miao X. Wang Z. Lu C. Yuan 《Journal of inclusion phenomena and macrocyclic chemistry》1999,35(1-2):211-224
Microporous and mesoporous molecular sieve materials with different channel structures and pore sizes were applied as supports for Fe-loaded catalysts to catalytically synthesize carbon nanotubes. The deposited carbon materials were characterized by the TEM technique. It was shown that the structures and pore sizes of supports greatly influence the forms and quality of the deposited carbon materials. The larger the pore size of the support used, the larger the diameter and pore size of the carbon nanotubes formed. It seems that the growth of carbon nanotubes can be orientated by the one-dimensional mesoporous structure of hexagonal mesoporous molecular sieve materials. 相似文献
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Juan Primera Anwar Hasmy Thierry Woignier 《Journal of Sol-Gel Science and Technology》2003,26(1-3):671-675
We introduce a new numerical technique for the calculation of the pore size distribution in two-dimensional disordered systems. Our method is based on a triangulation technique which allows a closer measurement of pores surface without any morphological hypothesis.In this work, we focus our calculations in simulated gels. Such materials are modeled in two different conditions: by means of the Diffusion-Limited and Reaction-Limited Cluster-cluster Aggregation algorithms, DLCA and RLCA, respectively. In both situations, when the particles concentration decreases, the average pores size increases. The more compact cluster in RLCA, compared with DLCA, is consistent with the pore size distribution we have calculated. The simulated mean pore size is quantitatively in agreement with experimental data from literature. 相似文献
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Jovita Moreno Rafael van Grieken Alicia Carrero Beatriz Paredes 《Macromolecular Symposia》2011,302(1):198-207
Summary: As known, the pore structure of the catalytic support plays a decisive role during the polymerization reactions determining intra-particle mass and heat transport phenomena. In this work, several ethylene polymerizations have been carried out by using as catalytic support different mesostructured materials with unimodal and bimodal pore size distributions in order to evaluate the influence of this pore size distribution on the catalytic behavior. Calcined mesoporous materials were impregnated with the catalytic system MAO/(nBuCp)2ZrCl2 and used for ethylene polymerization and ethylene/1-hexene copolymerizations, at 70 °C and 5 bar of ethylene pressure. Polyethylenes obtained were characterized by GPC, DSC and Crystaf. Results indicate that porous structure of the support has a significant influence on polymerization activity and polymer properties. Despite the catalyst bimodal pore size distribution, only ethylene/1-hexene copolymers presented a bimodal chemical composition distribution. 相似文献
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Giancarlo Espósito de Souza Brito Sandra Helena Pulcinelli Celso Valentim Santilli 《Journal of Sol-Gel Science and Technology》1994,2(1-3):575-579
Unsupported SnO2 membranes were prepared by sol-gel process and characterized by N2 adsorption-desorption isotherms and X-ray diffraction. Results show that the texture of dried samples does not change appreciably with the concentration of electrolyte. All of the pore size range used in ultrafiltration process was screened using sintering temperature between 300 and 700°C. 相似文献
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This work is focused on the elaboration of methodology for adsorption characterization of porous silicas by using benzene adsorption isotherms measured on good quality MCM-41 materials. Three MCM-41 samples were synthesized by using tetraethyl orthosilicate (TEOS) as silica source and surfactants, octyltrimethylammonium (C8), decyltrimethylammonium (C10) and cetyltrimethylammonium (C16) bromides as templates. A characteristic feature of this synthesis was relatively long hydrothermal treatment (5 days) at 373 K, which gave well ordered samples as evidenced by powder XRD analysis. Benzene adsorption isotherms measured on these MCM-41 samples were used to evaluate such standard quantities as the BET specific surface area, total pore volume, external surface area and the volume of ordered mesopores, and to obtain the statistical film thickness (t-curve) as well as the Kelvin-type relation, which describes the dependence between pore width and condensation pressure for benzene on silica at 298 K. The latter relations were incorporated into the Barrett-Joyner-Halenda algorithm to extend its applicability to calculate the pore size distributions from benzene adsorption data. 相似文献