Synthesis and Applications of Semiconducting Microporous Crystals

柱撑粘土是一种新型的微孔固体，它开辟了沸石以外的微孔晶体的新领域。在这个项目中，半导体层状钛酸盐已经与二氧化硅柱撑。研究了其吸附、催化性能及其应用. SiO2柱撑钛酸锰的合成及吸附性能用SiO2柱撑RbxMnxTi 2-XO 4（x=0.75）层状结构。Rb离子先与正烷基铵离子（CnH_2n +1 NH_3，n=6-18）交换，使钛酸酯层间空间分离，然后在层间水解正硅酸乙酯。烧掉有机部分产生具有大至500- 800 m2/g的表面积的二氧化硅柱撑微孔固体。对水、甲醇、甲苯和均三甲苯等多种气体的吸附-脱附等温线的测定表明，在层间形成的多孔结构与沸石非常相似，且均匀。孔显示疏水性。它们的大小估计为均三甲苯的数量级。SiO_2柱撑钛酸盐的孔结构控制在控制孔结构的尝试中，通过用KMnO_4氧化Rb_xMn_xTi_（2-x）O_4（x=0.75）来降低离子交换容量，然后类似地用SiO_2柱撑。人们曾预计，钛酸盐与降低的离子交换容量可以得到一个较小的孔径，然而，实验结果表明，得到一个较大的孔径。这一发现是重要的，应进一步研究与支柱形成的机制.硅柱撑钛酸锰在催化剂中的应用硅柱撑钛酸锰负载了多种离子。负载Cu离子的样品对CO的氧化表现出极高的催化活性，这可以从柱撑结构的高比表面积和微孔的rebox性质来解释。

Pillared clay is a new type of microporous solids which have opened a new field of microporous crystals other than zeolies. In this project, a semiconducting layred titanate has been pillared with silica. The adsorption and catalytic properties and their applications are studied.1. Synthesis and adsorption properties of silica pillared manganese titanateA layr structured RbxMnxTi2-XO4 (x=0.75) was pillared with silica. The Rb ions were first exchanged with n-alkylammonium ions (CnH2n+1NH3, n=6-18) to separate the interlayr space of the titanate, and then tetraethoxysilane was hydrolyzed between the layrs. Burning off the organic parts resulted in silica pillared microporous solids with a surface area as large as 500-800m2/g. The porous structure was stable up to 600ﾟC.Adsorption desorption isotherms for various vapors, water, methanol, toluene and mesitylene, were measured, which suggested that the porous structure formed between the layrs was very similar to those of zeolites, and uniform. The pores showed hydrophobic properties. Their size was estimated to be in the order of mesitylene.2. Control of micropore structures in silica pillared titanatesIn an attempt to control the pore structure, the ion exchange capacity of RbxMnxTi2-xO4 (x=0.75) was reduced by the oxidation with KMnO4, and then pillared with silica similarly. It had been expected that the titanate with a reduced ion exchange capacity could give a smaller pore size, however, the experimental results suggested that a larger pore size was obtained. This finding is important and should be further studied in relation with the mechanism of pillar formation.3. Application of silica pillared titanate to catalystsSilica pillared manganese titanates were loaded with various kinds of ions. The sample loaded with Cu ions showed an extremely high catalytic activity to oxidation of CO.This can be explained in terms of the high surface area of the pillared structure and the rebox properties of the micropores.