金屬奈米粒子之尺寸和形狀控制及其對乙醇氧化反應的影響

Abstract

本篇論文使用化學還原法合成了Pd、Pt、Ag、Au四種金屬的不同形狀、尺寸奈米粒子，並測試其對乙醇氧化的催化反應。藉由調整界面活性劑、還原劑及其他反應條件，來控制奈米粒子的尺寸和形狀。使用了穿燧式電子顯微鏡、X光繞射分析儀、和紫外-可見光光譜儀作特性鑑定，並沈積到支撐物氧化鋁上，作乙醇氧化的催化活性測試。 實驗結果發現，尺寸較小的Ag、Pd和方形Pd奈米粒子有較強的斷碳－碳鍵能力，能有效地使乙醇氧化成乙醛和二氧化碳；而Pt奈米粒子僅在斷碳－碳鍵的能力上有所提昇，生成較多的一氧化碳。另一方面，縮小Au奈米粒子的尺寸不僅能夠有效地提昇氧化能力，增加對乙醛的選擇率，同時也能夠減少乙烯的產生，避免形成碳沉積。

Different shaped and sized nanoparticles of Pd, Pt, Ag and Au have been synthesized by chemical reduction method and investigated for their catalytic activity of ethanol reforming. The sizes and shapes were controlled by adjusting the reagents of surfactants and reductants and the synthetic conditions. The synthesized nanoparticles were initially characterized by TEM, XRD and UV-Visible spectroscopy and further impregnated on Al2O3 supports for the catalytic reaction of ethanol oxidation. The catalysis result finds that the smaller sized Ag, Pd and cubic Pd nanoparticles show greater ability to break ethanol’s C-C bond and can effectively oxidize ethanol to acetaldehyde and carbon dioxide; while smaller Pt nanoparticles give greater C-C bond-breaking ability and produce a larger amount of carbon monoxide. On the other hand, decreasing in the size of Au nanoparticles raises their selective oxidation ability forming acetaldehyde and diminishes the formation of ethylene and carbon deposition.