中孔洞二氧化矽奈米複合材料對丙烯選擇 性氧化的應用

Mesoporous silica based nanocomposites for propene partial oxidation

劉君夏(Chun-Hsia Liu)

指導教授 ： 楊家銘

國立清華大學/理學院/化學系/博士(2013年)

摘要

本論文主要在探討中孔洞二氧化矽奈米複合材料的合成以及將其應用於丙
烯選擇性氧化的催化研究。在第一部分，SBA-15 的微孔洞被填入各種不同的金
屬鹽類，並且藉由升高燒結溫度至800 °C 來研究微孔洞的奈米限制效應如何限
制金屬氧化物奈米顆粒的成長。實驗的結果主要和金屬氧化物的表面自由能以
及其與二氧化矽間的相圖有關。在第二部分，Au/TiO2@SBA-15 奈米複合材料成
功地被合成出來並且應用於使用氧氣作為氧化劑和氫氣作為犧牲試劑的丙烯環
氧化反應中。催化結果顯示此催化劑具有穩定的丙烯產率並且副產物只有少量
的丙醛和丙酮。這個特別的催化結果和催化劑的設計有關–非常小的金奈米顆
粒座落在微孔洞中的二氧化鈦奈米顆粒表面，同時中孔洞為疏水表面。這樣的
催化劑設計，防止了產物環氧丙烯的二次反應。在第三部分，經由真空熱處理
的合成方式，吾人可以合成出具有高含量以及高分散性的銅觸媒在SBA-15 上的
奈米複合材料。並且將此材料應用在使用氧氣為氧化劑的丙烯選擇性氧化反應。
催化結果顯示出其對丙烯具有高轉化率以及對丙烯醛具有高產率。對丙烯具有
高轉化率主要是由於銅觸媒高度地分散在SBA-15 表面。本論文的結果顯示出，
在合成金屬氧化物奈米複合材料時，中孔洞表面疏水的SBA-15 是一個特別的載
體，以及顯示出合理的催化劑設計可以提升催化劑的效能。

關鍵字

中孔洞材料 ； 丙烯環氧化 ； 奈米複合材料 ； 金催化劑 ； 選擇性沉積 ； 金屬氧化物

並列摘要

The thesis focused on the preparation of mesoporous SBA-15 silica based nanocomposite and their application in the propylene partial oxidation. In the first part, various metal salts were deposited in the micropores of the SBA-15 support and the influences of the nano-confinement of micropores on the structural and textural properties of the resulting nanocomposite materials after heat treatment at temperatures up to 800 °C were studied. The observations were discussed based on the surface free energy of metal oxides and the phase diagrams of metal oxide with silica. In the second part, a nanostructured Au/TiO2@SBA-15 catalyst has been prepared and applied in propylene epoxidation with a mixture of O2/H2. The nanocomposite catalysts exhibited relatively stable propylene oxide (PO) production with small amounts of propanal and acetone byproducts. The unique catalytic behavior is related to the unique structure of very small Au nanoparticles on nanosized TiO2 phases located in the micropores and the hydrophobicity of the mesopores, which avoids further conversion of the reaction product PO. In the third part, SBA-15-supported high loaded and highly dispersed copper catalysts were prepared by vacuum-thermal treatment and applied in the propylene partial oxidation by using molecular oxygen as oxidant. They exhibited excellent activity and high yield of acrolein. The high activities were associated with the high dispersion of the copper species. The results of this thesis indicated that the SBA-15 with hydrophobic mesopores is a unique support to prepare oxide-containing nanocomposite materials and showed that the rational catalyst design would possibly improve the catalytic performance.

並列關鍵字

mesoporous material ； propene epoxidation ； nanocomposite ； gold catalyst ； selective deposition ； metal oxide

參考文獻

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