排序方式: 共有87条查询结果,搜索用时 31 毫秒
81.
P.G.N. Mertens S.L.F. Corthals X. Ye H. Poelman P.A. Jacobs B.F. Sels I.F.J. Vankelecom D.E. De Vos 《Journal of molecular catalysis. A, Chemical》2009,313(1-2):14-21
Bimetallic gold–palladium clusters, with an average size of 1.9 nm and composed of 80 mol% gold, proved to be highly active and selective metal catalysts for the organic phase oxidation with O2 of aliphatic, allylic and benzylic alcohols to the corresponding carbonyl products. Polyvinylpyrrolidone stabilized gold–palladium clusters dispersed in N,N-dimethylformamide emerged as promising quasihomogeneous metal catalysts for the oxidation of benzyl alcohol to benzaldehyde with full selectivity; they could be efficiently recycled with unaffected catalytic performance by solvent-resistant nanofiltration. Highly active and durable heterogeneous catalysts for the amide phase or solvent-free alcohol oxidation were prepared by the quantitative immobilization of the optimized gold–palladium clusters on the high surface area basic BaAl2O4 spinel support with preservation of the bimetallic clusters’ nanodispersion. 相似文献
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R. Navarro M.P. González I. Saucedo M. Avila P. Prádanos F. Martínez A. Martín A. Hernández 《Journal of membrane science》2008
In order to improve the performance of a nanofiltration membrane (DS5 DL from Osmonics®) several pre-treatments have been tested. Specifically, the membrane has been immersed, for different times, in an aqueous solution of HF or H3PO4, or of a mixture of both these acids. The chemical and charge properties of the membranes, both pre-treated and untreated, have been studied. 相似文献
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PES中空纤维复合纳滤膜的制备 总被引:2,自引:2,他引:0
采用界面聚合法制备聚醚砜(PES)中空纤维复合纳滤(NF)膜,讨论了制备条件对PES中空纤维复合NF膜性能的影响。实验结果表明,聚合反应时间、均苯三甲酰氯浓度、哌嗪浓度和酸吸收剂三乙胺浓度对复合NF膜性能有显著影响,同时二次反应能够提高复合NF膜的截留率,对2g/L的Na2SO4截留率可达到99.2%。 相似文献
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纳滤膜对电解质溶液分离特性的理论研究(I): 单一电解质溶液 总被引:1,自引:0,他引:1
电解质溶液在纳滤膜中的截留率对于膜法海水淡化和重金属离子的脱除非常重要. 本文假定膜具有狭缝状孔, 采用扩展Nernst-Planck方程、Donnan平衡模型和Gouy-Chapman理论来描述电解质溶液中离子在膜孔内的传递现象. 使用纯水透过系数、膜孔径及膜表面电势来表征纳滤膜的分离特征, 这三个参数可通过Levenberg-Marquardt方法由实验数据关联得到. 本文使用该模型计算了两种商用纳滤膜(NF45和SU200)对1-1型(NaCl, KCl, LiCl), 2-1型(K2SO4)和2-2型(MgSO4)单一电解质溶液的截留率, 并与实验数据进行了比较, 两者吻合较好. 计算结果表明电解质溶液中离子在纳滤膜孔内传递的主要机理是离子的扩散和电迁移, 纳滤膜对电解质溶液中离子的分离效果主要由空间位阻和静电效应决定. 该模型在低浓度时对电解质溶液通过纳滤膜的截留率计算结果较准确, 但对高浓度电解质溶液则偏差较大. 相似文献
85.
Coordination‐Driven In Situ Self‐Assembly Strategy for the Preparation of Metal–Organic Framework Hybrid Membranes
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Rong Zhang Prof. Shulan Ji Dr. Naixin Wang Lin Wang Prof. Guojun Zhang Jian‐Rong Li 《Angewandte Chemie (International ed. in English)》2014,53(37):9775-9779
Metal–organic frameworks (MOFs) have emerged as porous solids of a superior type for the fabrication of membranes. However, it is still challenging to prepare a uniformly dispersed robust MOF hybrid membrane. Herein, we propose a simple and powerful strategy, namely, coordination‐driven in situ self‐assembly, for the fabrication of MOF hybrid membranes. On the basis of the coordination interactions between metal ions and ligands and/or the functional groups of the organic polymer, this method was confirmed to be feasible for the production of a stable membrane with greatly improved MOF‐particle dispersion in and compatibility with the polymer, thus providing outstanding separation ability. As an experimental proof of concept, a high‐quality ZIF‐8/PSS membrane was fabricated that showed excellent performance in the nanofiltration and separation of dyes from water. 相似文献
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以DK膜为研究对象,以透过式流动电位测试系统为分析手段,采用动电法研究聚酰胺类纳滤膜的界面电现象。根据Helmholtz-Smoluchowski方程和Gouy-Chapman模型系统地考察了电解质溶液浓度和离子种类、价态等因素对膜ζ电位和电荷密度的影响。研究发现,在一定浓度范围内,DK型纳滤膜的电荷密度与电解质溶液浓度之间符合Freundlich吸附等温式,其中对于Na2SO4溶液:ln|σ|(mC/m2)=2.436 0.505lnC(mol/m3);对于MgSO4溶液:ln|σ|(mC/m2)=-0.539 1.412lnC(mol/m3);对于KCl溶液:ln|σ|(mC/m2)=-0.140 0.280lnC(mol/m3);对于CaCl2溶液:ln|σ|(mC/m2)=-2.287 1.105lnC(mol/m3)。结果表明,电解质溶液中阴离子的特性吸附是聚酰胺类纳滤膜荷电现象产生的主要原因。 相似文献