合成含金屬修飾之中孔洞材料及其在催化上的應用

Abstract

高分子化合物在化學上有極大的應用，本篇論文用親水的乙二醇甲基醚(ethylene glycol methyl ether)的末端以醯胺鍵結(amide link)的方式將三級碳溴2-溴-2甲基丙醯溴(2-bromoisobutyryl bromide)做為巨起始劑，利用ATRP (atom radical transfer polymerization)的技術合成出疏水端為丙烯酸甲酯(methyl acrylate)的雙區塊聚合物。以此雙區塊聚合物來當作合成中孔洞性材料的模板，調控不同比例的乙二醇甲基醚和丙烯酸甲酯，可以觀察到有立方結構(cubic)和二維六角排列(hexagonal)的中孔洞性材料產生，擁有較一般中孔洞材料大的孔洞、高表面積並且有良好的熱穩定性。 為了使此種中孔洞材料帶有酸性，去做非勻相的酸性催化，本篇論文分別修飾鈦、鋁和鈷在中孔洞材料中。鈦和鋁會在水熱時進入矽與氧的骨架之中形成帶有路易士酸性的中孔洞矽氧材料，而鈷則是利用在疏水端(MA)上做3-疊氮丙胺 (3-azidopropyl amine) 官能基修飾，並進一步將疊氮還原成胺基使之和鈷配位變成錯合物，讓鈷能夠在形成中孔洞矽氧材料時，均勻的分布在孔洞表面，而不是隨機分布。隨著金屬的修飾，對此中孔洞材料的結構及性質造成巨大的影響，利用這些金屬氧化物表面缺乏電子所造成的酸性，將在Friedel Crafts反應、酮或醛的ammomaximaion和苯胺的氧化上有不錯的催化效果。

Modified ordered mesoporous silicas were synthesized by the use of amphiphilic di-block copolymers as templates. The hydrophilic end of the copolymers was polyethylene glycol, whereas the hydrophobic end was polymethyl acrylate. By fixing the length of polyethylene glycol, polyacrylate end was constructed through the atom transfer radical polymerization(ATRP). With the use of copolymers PEO-PMA, we have synthesized Al or Ti modified silica mesoporous silicas successfully. With the different ratio of PEO and PMA, the mesostructure of the mesoporous silicas are variable. Due to the modification of Al and Ti into the -Si-O-Si- framework, these porous materials have the Lewis acidity. Modification of amine groups on the polyacrylate end allows the coordination of cobalt ions, which are grafted onto the di-block copolymers. Upon sol-gel process, cobalt oxide nanoparticles was also grouped into the mesoporous silicas. All of these modified mesoporous silicas show good catalytic activity for Friedel Crafts reaction、ammoximaiton of ketones or aldehydes and oxidation of aniline.