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有序介孔二氧化硅材料的形貌控制
山东大学硕士学位心文
表面活性剂浓度对介孔二氧化硅的形貌也有显著的影响,随着模板剂浓度的增 加,形貌由不规则蠕虫状外形向棒状外形转变,并最终形成表面光洁的螺旋球。 反应条件也会影响介孔二氧化硅的形貌,随着温度的升高,产物外形由卷曲的 片状逐渐经由半卷绕管状变成中空管;低酸度易形成规则多面体,高酸度则易 得到蠕虫状外貌。
particles,mesoporous spheres may be utilized in hi【曲·performance liquid
chromatography as a stationary phase There is currently intense in the topological construction of mesoporous
hydrothermal stability,controllable morphology,and easily functionalized surface
Ordered mesoporous materials mostly form mixtures of irregularly shaped and
materials both at the molecular and macroscale levels because the control of the particle morphology and size of mesoporous materials could open up new possibilities for their application,massive effects have been devoted to the synthesis of mesoporous molecular sieves having morphologies of defined size.Consequently Fabrication of mesoporous materials with controllable morphologies has been one of
Hence the morphologies and structures of the products can be controlled by the
changes of experiment conditions.And these researches will be very helpful in
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摘要
根据mPAC的规定,孔径在2 nm~50 nm之间的称为介孔,有序介孔材料
指孔径尺寸均一、孔道空间排列有序的多孔材料t因其具有规则有序的周期性 孔道结构,高度均一的孔径,极高的比表面积,良好的热稳定性和水热稳定性, 形貌可控,表面易功能化等一系列特点,使其在催化、吸附、生物大,}子分离、 传感器以及纳米材料的尺寸及维度控制方面具有广阔的应用前景·
particle shape changed from gyroids to fibers.Addition of ethanamide was fFra bibliotekvorable
to grow the products with hexagonal fiber shapes.Surfactant concentration,
the main subjects in this rapidly developing research field.In this thesis,we focused
on the controlling morphologies of ordered mesoporous silicas as our research directions,SO as to explore the possibility of controlling the topological construction ofmesoporous materials both at the molecular and macroscale levels.
sized particles.It is now apparent that morphology and texture of mesoporous materials are extremely important for industrial applications.For example, mesoporous films may be used in membrane separation and gas sensing.For the
在酸性静止条件下合成的球形、棒状、六角状、螺旋锥体、纤维和中空管 等形貌的有序介孔二氧化硅~般具有比较典型的MCM-41的六方孔道结构;比 表面积很大.通常大于1000m2,有的更高达1349 m2·g+l;孔体积极高,最高 达到1.594 cnl3·g一。共溶剂对介孔二氧化硅的形貌有较强的调控作用,增加甲 酰胺用量有利于形成纤维或管状外形:加入乙酰胺则有利于形成六角形纤维。
因此,通过调控合成参数,可以控制介孔氧化硅产物的形貌与结构。这些 研究为在微观上控制纳米材料结构.在宏观上控制其外观形貌,以合成出功能 性复合介孔材料提供必要的理论依据。
关键词:介孔二氧化硅材料,形貌控制,表面活性剂,共溶剂,模板技术
山东大学硕士学位论文
Abstract
According to the IUPAC recommendations,the pores with channel diameters in the range of 2-50 nm are referred to as mesopores.Ordered mesoporous materials are porous solids with uniform—sized pore regularly stacking in three-dimension. They are expected to show many potential applications in catalysis,adsorption, bio—molecule separation,sensor arrays,and controlled synthesis ofnanostmctures on size and dimension because they exhibit periodic ordered regular channels,very narrow pore size distribution,extremely high surface areas,high thermal and
BET surface areas of the samples Were in the range of 1000--1349 m2·911 and high
total pore volumes were up to 1.594 cm3·g一.Addition of formamide affected
本文以阳离子表面活性赉IJ十六烷基氯化毗啶为模板剂,甲酰胺或乙酰胺为 共溶剂,在酸性条件下合成了球形、棒状、六角状、螺旋锥体、纤维和中空管 等形貌的有序介+?L---氧化硅。利用扫描电子显微镜(SEM)、小角X射线衍射
(SXRD)和N2气体吸附-脱附等表征技术,研究了表面活性剂、共溶剂、pH、 温度等实验条件对介:fL--氧化硅的孔道结构、表面积、孔径分布、孔体积以及 形貌变化的影响。结论如下:
samples.The effects ofsurfactants,cosolvents,pH and temperature OtI pore structure, surface areas,pore size distribution,pore volume and morphologies were investigated.The main results were summarized as follows.
有序介孑L材料通常为不规则颗粒组成的粉体材料。随着应用研究的深入, 制备特定形貌的材料对于工业应用非常重要,而中间相的图案结构和方向按照 我们需要的方式排歹Ij是许多潜在应用最基本的要求,因此控制介孔材料的形貌,
探索特殊规整形貌的功能介孔材料的合成已成为当今材料学界的研究热点之 一。为此在本论文中我们选择有序介孔二氧化硅的形貌控制研究作为我们的研 究方向,探索既能在宏观上控制介孔材料生长,又能在微观上控制介孔分子筛 结构的新合成方法。这一方向同时涉及了仿生合成,纳米科学以及介孔材料科 学等几大热点领域,具有一定的理论和现实意义。
山东夫学硕士学位掩文
I
The ordered mesoporous silicas with particular morphology,such as sphere,rod, hexagonal rod,gyroid,fiber,and hollow tubule,were synthesized using cetylpyridinium chloride aS the template and formamide as the eosolvent.Scanning
temperature,acid concentration,and the addition of polar solvent were the
controlling factors in the morphology and nanostructure of the mesoporous materials.
The experimental results showed that the samples had hexagonal mesostructure analogous to MCM-41 and relatively narrow pore—size distributions 03m).Besides,