摘要本文介绍应用溶胶-凝胶法，合成具有介孔结构的中空二氧化硅微球。表面活性剂十六烷基三甲基溴化铵（CTAB）被用作为正硅酸乙酯（TEOS）在乙醇-水溶剂系统中的稳定剂，并引导TEOS的水解，氨水作为TEOS水解的催化剂。中空二氧化硅微球的粒径可以通过改变乙醇水的比例和改变CTAB的浓度实现，中空二氧化硅微球的球壳厚度与乙醇水的比值正相关。中空二氧化硅(乙醇水比例0.59)比表面积为907m2g-1，使用BJH法测量的孔脱附直径在2.8nm，表明其具有介孔结构。60112

使用此方法合成的中空二氧化硅微球为Li3PO4催化剂载体，催化环氧丙烷的异构化反应，与不使用二氧化硅负载的磷酸锂的催化效果进行比较。结果表明，使用中空二氧化硅作为催化剂载体，反应的催化效果与选择性，不如不使用负载的磷酸锂好。这可能是由于，大比表面积的中性二氧化硅降低了起到催化作用的碱性位点数目，使得转化率和选择性都有所下降。

毕业论文关键词 ：中空二氧化硅   溶胶-凝胶法   介孔   环氧丙烷   烯丙醇

毕业设计说明书（论文）外文摘要

Title    Synthesis of nanosized hollow mesoporous silica spheres and its application as support of lithium phosphate

Abstract

By adopting sol-gel/emulsion approach, hollow silica spheres with mesoporous structure were synthesized. In the process, the surfactant, cetyltrimethylammonium bromide (CTAB) was used to stabilize the oil droplet of tetraethoxysilane (TEOS) in the oil-in-water/ethanol system and to direct the hydrolysis of TEOS. The hydrolysis reaction was catalyzed by ammonia. The diameter of the hollow silica spheres, ranging from 895nm to 157nm, can be controlled either by changing the ratio(volume) of ethanol to water or by changing the concentration of the surfactant. The shell thickness of the spheres drops down when the ratio of ethanol to water decreases. BET area of the hollow silica sphere, which synthesized at the condition that the ratio of ethanol to water was 0.59, was determined to be 907m2g-1. The diameter of the mesoporous was at around 2.8nm as measured by BJH method.

The synthesized hollow mesoporous silica spheres were then employed as support of  lithium phosphate. The supported lithium phosphate was used to catalyze the isomerization reaction of propylene oxide to produce allyl alcohol. And its catalytical performance is compared with the unsupported lithium phosphate. In the comparison, the supported lithium phosphate did not lead to a higher conversion rate and selectivity. This phenomenon could be explained by the fact that the neutral SiO2, with large surface area, decreases the basic sites where the isomerization reaction are supposed to take place.

Keywords:  Nano hollow silica Template method Characterization Propylene oxide                                                 

目次

第一章 绪论 1

1.1  纳米科学与纳米材料 1

1.2 介孔材料的研究背景和分类 1

1.3 中空形纳米材料的研究和发展现状 2

1.4 中空纳米二氧化硅微球的制备方法及研究现状 2

1.4.1 溶胶-凝胶法 2

1.4.2 层层组装法 3

1.4.3 乳液法 4

1.4.4 沉淀法 4

1.5 本课题的主要研究内容 4