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以混合表面活性剂为模板可控合成MCM-48和MCM-41分子筛 总被引:2,自引:0,他引:2
利用阳离子和三嵌段共聚物混合表面活性剂为模板,在水热条件、碱性介质中可控合成出MCM-48和MCM-41分子筛。在固定P123(聚氧乙烯-聚氧丙烯-聚氧乙烯三嵌段共聚物):TEOS(正硅酸乙酯)(物质的量的比)为0.01875的体系中,调节CTAB(十六烷基三甲基溴化铵)∶TEOS(正硅酸乙酯)物质的量比值m,当m在0.12~0.13范围合成出MCM-48分子筛;当m在0.04~0.08范围合成出MCM-41分子筛。通过XRD,TEM,N2物理吸附,IR等方法进行了表征。结果表明:聚氧乙烯-聚氧丙烯-聚氧乙烯三嵌段共聚物(P123)的加入可以更大程度地降低合成介孔材料所需阳离子表面活性剂的用量;可控合成的介孔材料具有高比表面积、高度有序的孔道结构、较集中的孔径分布。 相似文献
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以混合阳离子-嵌段共聚物表面活性剂为模板合成介孔MCM-48 总被引:1,自引:1,他引:1
利用阳离子和嵌段共聚物混合表面活性剂为模板,在水热条件、碱性介质中成功地合成出MCM-48介孔分子筛。在1TEOS(正硅酸乙酯)∶0.125CTAB(十六烷基三甲基溴化铵)∶nP123(聚氧乙烯-聚氧丙烯-聚氧乙烯三嵌段共聚物)∶0.50NaOH(氢氧化钠)∶61H2O(物质的量的比)体系中,n值在较大范围内(0.000 625~0.018 75)可调。通过粉末X射线衍射(XRD)、N2物理吸附、扫描电镜(SEM)对合成样品进行表征。结果表明:聚氧乙烯-聚氧丙烯-聚氧乙烯三嵌段共聚物(P123)的加入可以更大程度地降低合成MCM-48所需阳离子表面活性剂的用量;合成的MCM-48具有高比表面积、高度有序的孔道结构、较集中的孔径分布和较高的热和水热稳定性。 相似文献
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阳离子与非离子混合表面活性剂模板合成介孔SiO2 总被引:9,自引:0,他引:9
利用各种两亲分子有序组合体构成超分子模板,合成从介观到宏观尺度不同形态的无机材料成为材料科学新崛起的研究方向[1].介孔SiO2在催化、吸附、分离介质及化学传感器等方面有广阔的应用前景. 相似文献
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混合表面活性剂模板法合成立方相介孔含钛氧化硅 总被引:12,自引:0,他引:12
自1992年Mobil公司的M41S系列介孔氧化硅分子筛问世以来[1,2],借助表面活性剂液晶模板方法合成各种孔结构与不同大小孔径的硅基分子筛材料引起了人们的极大兴趣,目前多数工作仍然集中于六方相的介孔分子筛.具有双连续的三维交织立方排列孔道结构的MCM48由于其孔道不易堵塞和良好的骨架结构稳定性[3,4],在催化、吸附和与其为载体的制备等方面具有独特的应用价值.但由于液晶模板形成立方相区的范围非常狭窄,相应的分子堆积比对模板剂分子几何结构要求较苛刻,采用单一表面活性剂为模板剂合成时,条件难以掌握,制备MCM48十分困难.H… 相似文献
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Since Mobil researchers reported the discovery of a new family of silica-based mesoporous molecular sieves (M41S) materials in 1992[1,2], there has been a growing interest in using these materials as heterogeneous catalysts, catalyst supports, and nanocomposite host materials for novel applications. All these applications have stimulated many researchers to synthesize mesoporous materials via different templating schemes or synthesis pathways. So far, ionic and neutral surfactant including neutral alkylamine[3], polyethlene oxide[4], genimi[5], and amphiphilic triblock copolymer[6] have been the most commonly used as templates for the directing the formation of mesoporous. 相似文献
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A systematic study of the factors governing the formation of Nb-TMS1, a niobium-based mesoporous hexagonally-packed transition metal oxide molecular sieve, is reported. The synthesis of this material was achieved through a novel ligand-assisted liquid crystal templating mechanism in which a discrete covalent bond is used to direct the templating interaction between the organic and inorganic phases. In general, the synthesis of Nb-TMS1 is more strongly affected by starting conditions such as temperature, surfactant-to-metal ratio, pH, and solvent than by temperature and time of aging after the initial hydrolysis step. The results also show that Nb-TMS1 can be synthesized under conditions which strongly disfavor the formation of micelles. This suggests that Nb-TMS1 is formed via a mechanism involving self-assembly with concomitant condensation. It was found that with increasing surfactant-to-metal ratios, new hexagonal P63/mmc (Nb-TMS2) and layered (Nb-TMS4) phases could be formed, while increasing the surfactant chain length led to a new cubic phase (Nb-TMS3). Crystals of Nb-TMS1 of up to several mm in dimensions were also grown. These crystals are larger than the biggest mesoporous crystals reported by a factor of 3 orders of magnitude. These crystals retain their structure on micelle removal by acid treatment and are thus of great interest as hosts for quantum wires. 相似文献
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ThediscoveryofM41SfamilyofmesoporousmolecularsievesbyMobilresearchersI'2hasstimulatedconsiderableinterestintheuseofthesematerialsascatalysts,catalystsupports,aswellasadsorbents3'#.Intheoriginalreport"=,MCM-41waspreparedfromaself-assemblyprocesswhichinvolveselectrostaticinteractionsbetweenpositivelychargedquaternaryammoniummicelles(S )andinorganicanions(l-)usedasframeworkprecursors.Huoetal5extendedtheelectrostaticassemblyapproachesbyproposingfourcomplementarysynthesisschemes(S l-,S-I ,S X-… 相似文献
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模板剂对全硅MCM-41介孔分子筛结构的影响 总被引:10,自引:0,他引:10
分别采用十六烷基三甲基溴化铵和十六烷基三乙基溴化铵作为模板剂,硅溶胶为硅源,用水热晶化法在碱性(NaOH)介质中合成了MCM-41介孔分子筛样品.通过XRD、N2吸附-脱附、TG-DTA、IR等测试手段对这两种样品进行了对比表征分析.考察了两种不同模板剂对其晶体结构、比表面及孔径大小的影响.实验结果表明,相对于十六烷基三甲基溴化铵做模板剂,采用大头基的十六烷基三乙基溴化铵可以合成较大孔径和孔容(分别为4.72 nm和1.14 cm3•g-1)的MCM-41介孔分子筛,而且具有较窄的孔径分布,因此对于合成大孔径的介孔分子筛MCM-41,十六烷基三乙基溴化铵是一种很好的模板剂. 相似文献