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介孔二氧化锆分子筛的合成机理述评 总被引:2,自引:1,他引:2
MCM-41介孔分子筛的成功开发,不仅打破了微孔分子筛在吸附、择形催化、吸附分离等领域的应用局限性,而且拓宽了新型材料的制备途径.它使人们在材料合成中由过去仅有的经典单分子作用机制,拓展到多分子的液晶模板机理,即超分子自组装过程.由此可以清楚地看到介孔分子筛的开发为人们探索新材料、新结构提供了另一途径,即引入表面活性剂胶束/液晶导向结构. 相似文献
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介孔分子筛MCM-41的水热稳定性 总被引:3,自引:0,他引:3
介孔分子筛MCM-41在催化、吸附分离以及化学组装制备先进材料等方面具有潜在的巨大应用价值,但MCM-41的低水热稳定性使其在催化研究领域中的应用受到了极大的限制。因此,提高介孔分子筛的水热稳定性具有十分重要的科研和实际应用意义。笔者对介孔分子筛MCM-41低水热稳定性的原因作了简要分析,并系统地介绍了近几年来在提高介孔分子筛水热稳定性方面的研究工作。 相似文献
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介孔分子筛研究新进展 总被引:3,自引:3,他引:3
介孔分子筛材料作为催化剂或催化剂载体为有机大分子参与反应提供了有利的空间构型和择形活性中心,在石油加工工业中具有潜在的应用优势。但由于介孔分子筛材料的水热稳定性比较低,且酸性较弱,极大地影响了其在催化领域中的广泛应用。本文综述了近年硅基介孔分子筛的改性研究进展,重点讨论了在提高介孔分子筛酸性和水热稳定性方面的研究工作。 相似文献
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介孔分子筛的酸性和水热稳定性 总被引:27,自引:0,他引:27
介孔分子筛材料在催化、吸附与分离以及化学组装制备先进材料和分子器件等方面具有潜在的应用价值.但是,由于介孔分子筛材料较低的水热稳定性和较弱的酸性,极大地影响了其在催化研究中的广泛应用.本文系统地综述了最近几年在提高介孔分子筛酸性和水热稳定性的研究工作.其中包括:(1)将超酸组份负载于介孔分子筛的孔道中以达到提高介孔分子筛材料的酸强度的目的;(2)通过在合成介孔分子筛的过程中加入无机盐和有机胺等助剂或采用合适的后处理方法以提高介孔分子筛的水热稳定性;(3)通过新型模板剂来合成具有较高水热稳定性的介孔分子筛材料;(4)利用具有沸石分子筛基本结构单元的沸石分子筛导向剂与表面活性剂自组装来合成具有强酸中心和高温水热稳定的介孔分子筛材料. 相似文献
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超声波合成介孔分子筛 总被引:17,自引:0,他引:17
介孔分子筛MCM鄄41自问世以来一直是材料研究的热门领域之一[1,2],目前报道的主要合成方法有水热合成法[3,4]、微波法[5,6]等。其中水热法反应时间长达3~5d,耗能大,不利于实用化生产。超声波化学又称声化学,是一门新兴的交叉学科。超声波的波长远大于分子尺寸,因而不能对分子直 相似文献
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以MCM-22为原料合成高水热稳定性的介孔材料 总被引:3,自引:0,他引:3
以合成的微孔分子筛MCM-22为原料,将其与表面活性剂及氢氧化钠一起回流溶解,再调节溶液的pH值至7~9, 使MCM-22转化为高水热稳定性的介孔材料. 所得介孔材料具有蠕虫状的均匀孔道,骨架中不含有MCM-22的微观结构单元. 该介孔材料至少含有18%的表面活性剂,经823 K焙烧脱除表面活性剂后,其孔径为2 2 nm, 比表面积为 1 038 m2/g, 孔容为0 97 cm3/g. 焙烧后的介孔材料具有非常高的水热稳定性,经沸水回流100 h后其比表面积为896 m2/g, 孔容为0 90 cm3/g, 孔径为2 1 nm, 即使经过300 h的回流,该材料仍能保持698 m2/g的比表面积和0 90 cm3/g的孔容. 固体 29Si MAS NMR结果表明,该介孔材料的高水热稳定性与其高表面缩合度有关. 相似文献
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一种合成高水热稳定性微孔-介孔复合分子筛β沸石/MCM-41的新方法 总被引:10,自引:0,他引:10
首次以β沸石作为硅铝源制备了β沸石/MCM-41微孔-介孔复合分子筛材料,通过XRD、IR、N2吸附脱附、SEM和水热处理等手段对复合材料进行了表征,并与MCM-41和β沸石及二者的机械混合物的有关性能进行了对比研究。结果表明,复合分子筛明显不同于机械混合物,其水热稳定性远远高于普通方法合成的介孔分子筛,而且发现通过改变体系的nNa/nSi比,可以调变复合样品中的微孔、介孔相的相对含量。 相似文献
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Periodic Mesoporous Organosilicas (PMOs) with 2D-hexagonal and cubic Pm3n structures have been prepared from bis(trialkoxysilyl)ethane and cetyltrimethylammonium chloride. The two samples have been pyrolyzed under argon up to 1000 °C. Study by X-ray diffraction (synchrotron radiation) allows the thermal stability of both structures to be followed as a function of the pyrolysis temperature. While the 2D-hexagonal structure collapses after pyrolysis at 800 °C, the cubic Pm3n structure is retained up to 1000 °C. Further characterizations were performed by 29Si MAS-NMR, N2 adsorption-desorption experiments and elemental analysis. At 1000 °C, the first sample can be described as a mixture of silica and a free C phase, while the cubic one is a true SiCO glass with mixed SiCxO4 – x units (x = 0,1,2) and a very large surface area of 730 m2/g. 相似文献
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Dr. Thanh‐Dinh Nguyen Dr. Kevin E. Shopsowitz Prof. Dr. Mark J. MacLachlan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(45):15148-15154
Liquid crystalline phases can be used to impart order into inorganic solids, creating materials that mimic natural architectures. Herein, mesoporous silica and organosilica films with layered structures and high surface areas have been templated by nanocrystalline chitin. Aqueous suspensions of spindle‐shaped chitin nanocrystals were prepared by sequential deacetylation and hydrolysis of chitin fibrils isolated from king crab shells. The nanocrystalline chitin self‐assembles into a nematic liquid‐crystalline phase that has been used to template silica and organosilica composites. Removal of the chitin template by either calcination or sulfuric‐acid‐catalyzed hydrolysis gave mesoporous silica and ethylene‐bridged organosilica films. The large, crack‐free mesoporous films have layered structures with features that originate from the nematic organization of the nanocrystalline chitin. 相似文献
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以阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)为模板剂,采用水热合成法制备了中孔氧化钛原粉,再采用磷酸和氯化铝溶液依次对中孔氧化钛原粉进行后处理,得到了具有高热稳定性的中孔Ti-P-Al材料. 通过粉末X射线衍射、透射电子显微镜和氮物理吸附等方法对样品进行了表征. 结果表明,反应凝胶组成对样品的中孔结构有较大的影响,当反应凝胶配比为Ti(SO4)2∶CTAB∶H2O=1∶0.54∶430, 温度为363 K, 处理时间为10~20 min时,所得的TiO2原粉具有较规整的中孔结构. 此样品经过0.25 mol/L的磷酸处理后有序性有较大程度的提高. 将磷酸处理过的样品进一步用氯化铝溶液处理,得到了中孔结构的Ti-P-Al材料,此材料经过873 K焙烧后仍具有典型的中孔特征,其比表面积为 382 m2/g, 孔径为3.13 nm. 相似文献
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Zhen Li Bin Dong Fei Geng Ganzuo Li 《Journal of Dispersion Science and Technology》2013,34(8):1066-1071
This article reports a novel preparation of mesoporous silica with series of 1-alky-3-methylimidazolium bromide (CnMIM)Br (n = 12, 14, 16), a kind of amphiphilic room-temperature ionic liquids (RTILs), as a template via a sol-gel nanocasting technique. The pore morphology and structures of these mesoporous silica were characterized by Transmission electron microscopy (TEM). The results show that the RTIL bearing longer alkyl chain is preferred to form the mesoporous silica material with bigger pores. (C16MIM)Br has been chosen to study how the various influencing factors affect the synthesis and structure of the mesoporous silica material, such as the acid concentration, the solling time, the gelling time and the calcination time. N2 adsorption-desorption isotherms measurement was used to characterize the pore size distribution and BET surface area. The results indicate that all of the factors can make an influence on the preparation of the mesoporous silica, which is more sensitive to the concentration of the acid. 相似文献
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通过一种新颖的方法,即软模板-固液技术(CSSL)合成具有高比表面积的介孔纳米晶体氧化锆.首先,通过软模板法以1-十六烷基-3-甲基咪唑溴(C16mim+Br-)为结构导向剂,硫酸锆为无机前驱物合成了介观相氧化锆杂化物,然后该杂化物与固体硝酸铜无机盐研磨并进行热处理.在600℃焙烧后所得到的氧化锆材料具有蠕虫状介孔结构,且孔壁由尺寸约为2.50nm的四方相氧化锆纳米粒子组成.该材料的比表面积为240.0m2·g-1,孔径为4.10nm.与之对应,使用单一的软模板法在相同的温度焙烧后,所得到的氧化锆材料介孔结构坍塌,比表面积仅为9.5m·2g-1. 相似文献
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Hollow-structured mesoporous silica has wide applications in catalysis and drug delivery due to its high surface area, large hollow space, and short diffusion mesochannels. However, the synthesis of hollow structures usually requires sacrificial templates, leading to increased production costs and environmental problems. Here, for the first time, amino-functionalized mesoporous silica hollow spheres were synthesized by using CO2 gaseous bubbles as templates. The assembly of anionic surfactants, co-structure directing agents, and inorganic silica precursors around CO2 bubbles formed the mesoporous silica shells. The hollow silica spheres, 200–400 nm in size with 20–30 nm spherical shell thickness, had abundant amine groups on the surface of the mesopores, indicating excellent applications for CO2 capture, Knoevenagel condensation reaction, and the controlled release of Drugs. 相似文献
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ChengTAO JianGuoHUANG JunBaiLI 《中国化学快报》2003,14(11):1175-1178
“Noodle-like” mesoporous silica with a diameter of about 180 nm and a length of ca. 10μm was prepared through sol-gel process by using poly(sodium 4-styrenesulfonate) (PSS)/cetyltrimethylammonium bromide (CTAB) complex as template. Parallel oriented regular mesopores with a diameter of around 2-4 nm are distributed along the wall of the particles, while the “worm-like” disordered mesopores can be found in the fringe part. This approach provides a new series of templates and a novel route to prepare inorganic mesoporous materials with special morphology. 相似文献