Hydrothermal Fabrication and Catalytic Properties of YBa 2 Cu 3 O 7 Single Crystallites for Methane Combustion
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Hydrothermal Fabrication and Catalytic Properties of YBa2Cu3O7 Single Crystallites for Methane Combustion Yue Zhang • Lei Zhang • Jiguang Deng Hongxing Dai • Hong He
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Received: 23 October 2009 / Accepted: 29 November 2009 / Published online: 5 January 2010 Ó Springer Science+Business Media, LLC 2009
Abstract The YBa2Cu3O7 nano/microsized single crystallites with spherical and rod-like morphologies were fabricated hydrothermally. The catalytic performance of the materials was evaluated for methane combustion. It is shown that there was a clear relationship between the a-oxygen desorption or initial H2 consumption rate and catalytic activity. The single-crystalline perovskite-like cuprate catalysts outperformed the polycrystalline counterpart. The good catalytic performance of the hydrothermally derived YBa2Cu3O7 single crystallites is associated with more a-oxygen adspecies, better low-temperature reducibility, high-quality single crystallinity, and unique morphology. Keywords Perovskite-like oxide catalyst Single crystalline YBa2Cu3O7 Hydrothermal synthesis Specific morphologies Methane combustion
1 Introduction In the past decades, a large number of materials, such as noble metals, transition metal oxides, and mixed oxides (e.g., perovskite-type oxides, perovskite-like oxides, and hexaaluminate [1–3]), have been tested as catalyst for the combustion of light hydrocarbons. Although supported PdO catalysts have been believed to perform the best for methane combustion [4], such materials are expensive and suffer from drastic deactivation at high temperatures
Y. Zhang L. Zhang J. Deng H. Dai (&) H. He Laboratory of Catalysis Chemistry and Nanoscience, Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, 100124 Beijing, People’s Republic of China e-mail: [email protected]
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([700 °C) due to sintering [3], hence limiting their extensive applications. Among the base metal-based catalysts, perovskite-type and perovskite-like oxides show promising performance in catalyzing the oxidation of methane. The latter possesses higher thermal stability than former [5, 6], and show good catalytic activities for the total oxidation of carbon monoxide [7, 8], propane [7], and methane [9]. YBa2Cu3O7 (YBCO) is a high temperature superconductor with an orthorhombic triple-layered perovskite-type structure. Various methods, such as the precursor combustion [10], sol–gel [11], biopolymer templating [12], and anodic aluminum oxide (AAO) templating techniques [13, 14], have been adopted to prepare YBCO superconductors. This perovskite-like oxide shows good catalytic performance for the hydrogenation of CO or CO2 to methanol [15–17], the oxidation of methane [18, 19], and the decomposition of N2O [20]. The perovskite-type and perovskite-like oxides prepared by means of the above methods are usually polycrystalline. In recent years, single crystalline perovskite-type and perovskite-like oxides have been fabricated using hydrothermal treatmen
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