mICROANALYSIS OF dEPOSITION AND ELECTROCHEMICAL oXIDATION OF cARBON ON AN eLECTROCHEMICAL SYSTEM UNDER hYDROCARBON gASES

碳氢化合物气体下电化学系统中碳的沉积和电化学氧化的微分析

• 批准号: 12450323
• 负责人: KAWADA Tatsuya
• 金额: $ 9.22万
• 依托单位: TOHOKU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12450323/
• 关键词: Raman microscope; carbon deposition; solid oxide fuel cell; SOFC; steam reforming; nickel electrode; platinum electrode; electrode reaction kinetics; ラマン分光; 改質反応; 部分酸化反応; 赤外分光; 部分酸化

In-situ Raman microscope analysis was performed to investigate carbon deposition and its electrochemical oxidation on a fuel electrode of a solid oxide fuel cell, and the following results were obtained.1. We have developed a sample heating stage that was specially designed for high temperature electrochemical testing under optical microscope and Raman microscope. Two separate chambers were installed into the stage, which enabled a sample electrolyte pellet to be placed under fuel gas and air. By using the heating stage, it was possible to investigate observe carbon deposition processes at electrode/electrolyte system under a thermodynamically controlled atmospheres.2. Electrochemical oxidation process of methane was investigated by combined electrochemical measurements and gas analysis. It was found that oxidation of methane proceeds not directly but via local steam reforming processes on the electrode.3. Platinum and nickel model electrodes were fabricated on yttria stabilized zirconia electrolyte pellets. Microscopic observation of the carbon deposition, as well as the characterization of the deposited carbon were performed under methane and liquid petroleum gasses (LPG, n-butane). In the case of platinum electrode under LPG, two Raman bands called 'D-band' and 'G-band' were observed indicating the deposition of disordered carbon and graphite, respectively. The deposition of carbon can be observed also by optical microscope as color change of electrode surface. Optical microscope observation revealed that the carbon is deposited not uniformly on the electrode but expands gradually from the position where the first carbon is deposited. On the other hand, on a nickel electrode under methane fuel, only graphite was found by Raman spectroscopy. The deposited graphite was hard to be removed by electrochemical pumping of oxygen through the electrolyte.

采用原位拉曼显微镜分析研究了固体氧化物燃料电池燃料电极上的碳沉积及其电化学氧化过程，得到以下结果.我们开发了一种样品加热台，专门用于光学显微镜和拉曼显微镜下的高温电化学测试。两个独立的腔室被安装到该阶段，这使得样品电解质颗粒被放置在燃料气体和空气下。通过使用加热阶段，可以研究在可控气氛下观察电极/电解质体系的碳沉积过程.采用电化学测试和气体分析相结合的方法研究了甲烷的电化学氧化过程。研究发现，甲烷的氧化不是直接进行的，而是通过电极上的局部水蒸气重整过程进行的.在氧化钇稳定的氧化锆电解质颗粒上制备铂和镍模型电极。在甲烷和液化石油气（LPG，正丁烷）下进行碳沉积的显微镜观察以及沉积碳的表征。在液化石油气下的铂电极的情况下，两个拉曼带被称为“D-带”和“G-带”观察到指示无序碳和石墨的沉积，分别。用光学显微镜观察电极表面颜色的变化，也可以观察到碳的沉积。光学显微镜观察显示，碳不均匀地沉积在电极上，而是从第一个碳沉积的位置逐渐膨胀。另一方面，在甲烷燃料下的镍电极上，通过拉曼光谱仅发现石墨。沉积的石墨很难通过电解质中的电化学泵氧去除。