Noble metal nanoparticles supported on amino-functionalized mesoporous silica as catalyst for tandem reaction
Sun, Qian (2017)
Sun, Qian
Tampereen ammattikorkeakoulu
2017
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Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:amk-2017091915232
https://urn.fi/URN:NBN:fi:amk-2017091915232
Tiivistelmä
Mesoporous materials are a type of porous materials with ordered pores on the range of 2-50 nanometers, which have attracted great attention because of wide applications in adsorption, separation, catalysis, electrode materials, chemical sensors and optoelectronic devices, and so on, due to their high surface area, ordered mesopores and tunable pore distribution. The pore size of mesoporous silica is large enough to accommodate a variety of large molecules, and the high density of silanol groups on the pore wall is beneficial to the introduction of functional groups with a high coverage. Recently, many researches have focused on the catalytic action of amino-functionalized mesoporous silica. Here, the aim is to synthesize a bifunctional mesoporous silica Pd@NH2-MSNSs, the process of synthesis is as follows. Using an anionic surfactant as the template and organosilane as co-structure directing agent, amino-functionalized mesoporous silica nano spheres (NH2-MSNSs) were synthesized by self-assembly. After extraction of the anionic surfactant templates by solvent, silica nano-spheres with ordered and radially oriented amino-functionalized mesochannels were obtained. Then, we utilized the amine groups immobilized on the mesoporous surface as stabilizing and capturing agents to prepare Pd nanoparticle supported NH2-MSNSs catalysts. The Pd-supported catalysts exhibited high and stable activity in aerobic oxidation of benzyl alcohol, which is benefit for the tandem reaction of alcohol oxidation to dehyde and Knoevenagel condensation reaction. The di-functional mesoporous silica Pd@NH2-MSNSs exhibited better catalytic action than mono-functionalization mesoporous silica NH2-MSNSs and Pd@MSNSs. 介孔材料是指孔径介于2-50nm的一类多孔材料。由于其高比表面积,有序孔道和孔径分布连续可调等特点,在吸附、分离、催化、电极材料、化学传感器和光电器件等方面有广泛的应用价值。介孔二氧化硅的孔径足够大以容纳各种分子,硅醇基团的高密度孔壁有利于功能化得到最大体现。近年来,许多研究都集中在氨基功能化介孔二氧化硅的催化作用上。在这篇论文中,我的目的是合成双功能化的介孔二氧化硅催化剂Pd@NH2-MSNSs,合成过程如下:采用阴离子表面活性剂作为模板,以有机硅烷作为共结构导向剂,通过自组装方法合成氨基功能化的介孔二氧化硅纳米球。利用氨基功能化的介孔材料作为催化剂的基础。用溶剂萃取阴离子表面活性剂模板后,得到了径向有序的氨基功能化介孔二氧化硅纳米球。然后,我们利用固定在介孔表面上的胺基团作为稳定剂和捕获剂来使Pd纳米颗粒负载在NH2-MSNSs催化剂上。这个负载型催化剂在苯甲醇的空气氧化过程中表现出较高的活性,这有利于醇氧化为醛的连串反应和Knoevenagel 浓缩反应。双功能化的介孔二氧化硅催化剂Pd@NH2-MSNSs比单功能化介孔二氧化硅催化剂NH2-MSNSs 和 Pd@MSNSs 表现出更好的催化作用。