承載於金屬氧化物修飾之多壁奈米碳管之鈀與金觸媒應用於電催化反應之研究

Electrocatalysis Applications of Palladium and Gold Catalysts Supported on Metal Oxide Modified Multi-Walled Carbon Nanotubes

邱郁菁(Yuh-Jing Chiou)

指導教授 ： 林鴻明

大同大學/工程學院/材料工程學系所/博士(2011年)

摘要

對於應用於直接甲酸燃料電池而言，適當修飾的鈀觸媒被認為具有優異的電催化特性而引起廣泛的研究興趣。為改善催化效能及避免觸媒毒化問題，本研究利用含浸法與多元醇法合成具固溶相雙金屬的金-鈀觸媒，並承載於氧化鈰或氧化鈰鋯修飾過的奈米碳管載體。研究中以ICP、XRD、及TEM檢測產物的組成、結構與表面形貌。這些基本檢測皆證實與原實驗設計有良好一致性。
對於氧化鈰或氧化鈰鋯修飾過的奈米碳管載體，由於氧化鈰或氧化鈰鋯具中度多孔結構，同時可能由於含浸過程中再度將奈米碳管破碎化，修飾過的奈米碳管比起未修飾過的奈米碳管有較大的比表面積。金屬鋯的添加會降低氧化物中晶格氧的脫附溫度。而金屬承載於載體之後，載體的比表面積減少。鈀金屬為催化TPD脫附反應的主因。
在電催化特性實驗中，實驗結果顯示：具固溶相雙金屬的金-鈀觸媒能避免鈀金屬在電催化反應中溶出，而氧化物修飾過的奈米碳管載體，則可避免觸媒被毒化的問題。所有的觸媒皆能在150~250oC將CO完全氧化，較高的鈀含量觸媒其CO 100%轉化溫度較低。本研究認為形成金-鈀固溶相與氧化物修飾的奈米碳管載體能降低反應活化能而有較好的催化特性。

關鍵字

燃料電池 ； 鈀 ； 觸媒 ； 奈米碳管

並列摘要

For the application of direct formic acid fuel cell, Pd catalyst with some modification attracts the study attention for its electrocatalytic advantages. To benefit the catalytic performance and prevent the catalyst poison problem, this study develops Pd basis catalysts, which have solid solution phase with Au and ceria/ceria-zirconia modified MWCNTs substrate, by impregnation and polyol methods. The composition, structure and morphology are analyzed by ICP, XRD and FETEM, respectively. For Au-Pd bimetal catalysts, the formation of solid solution phase and the compositions of the catalysts are proved to be consistent with the initial designation.
For MWCNTs modified by ceria or ceria-zirconia, both mesoporous structure of ceria/ceria-zirconia and the advanced breaking of MWCNTs in the impregnation process may cause the surface area increasing of MWCNTs. Zr doping may decrease the temperature of lattice oxygen desorption. The addition of metal can fill the defect of the substrate and decrease the surface area. Pd is the main dominant to promote the reaction and lower the reaction temperature in the TPD helium process.
In electrocatalysis, Au-Pd solid solution can prevent the leaching of Pd in formic acid, while the oxide modified support can prevent catalyst poison. The prepared catalysts can totally convert CO between 150~250oC. More Pd can convert 100% CO at lower temperature. It can be considered that, both the formation of solid solution, Au-Pd, and the oxide modification of MWCNTs can decrease the activation energy of the catalyzing reaction and have better catalytic performance.

並列關鍵字

CNT ； Fuel cell ； Pd ； Catalyst

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