HIGH-PERFORMANCED Cu/Al2O3 CATALYST FOR METHANOL STEAM REFORMING

• Main Authors: Jian-shin Liou, 劉建新
• Other Authors: Ienwhei Chen
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/46383045858059862862

碩士 === 大同工學院 === 化學工程研究所 === 87 === The objective of this research was to investigate the high-performanced Cu/Al2O3 catalyst applied in methanol steam reforming, in which methanol would react to form hydrogen used in fuel cell. This experiments were carried out to investigate the effects of addition of Cr and oxygen-ionic conducting yttria doped ceria(YDC) on Cu/Al2O3 for CH3OH steam reforming. TPR technique was used to analyze the composition, Cu surface area and Cu dispersion of catalyst. XRD was to identify the crystal composition of catalyst. BET was to measure the total surface area and pore size of catalyst. SEM to observe metal crystal structure and change on the surface of catalyst. The methanol steam reforming reaction was carried out in fixed-bed reactor at designed temperature and ambient pressure, and the products were on-line into GC. The results showed that the total surface area of g-Al2O3 would be decreased by the addition of metals such as Cu, Cr, Y and Ce, and that was due to the blockage of partial small pores such that larger pores leaved and BET surface area became smaller than that of g-Al2O3. The addition of Cr would lower the reduction temperature of Cu, and Cu15-Y2Ce10/Al2O3 could produce the most active Cu+, which resulted in a higher activity. The addition of Ce or Cr would increase the copper dispersion and copper surface area. However, addition of YDC to catalysts would inhibit copper dispersion and made copper surface area be lower than that of g-Al2O3 support. SEM photos also showed that Ce addition could enhance the dispersion of copper. For CH3OH steam reforming, the addition of YDC would improve the activity of Cu/Al2O3 catalyst, and Cu15-Y2Ce10/Al2O3 showed the best activity. YDC addition to copper catalysts could raise activities so much was characteristic of oxygen vacancies of YDC, and CH3OH steam reforming reaction was used to promote the production of more active Cu+ that could increase the rate of the rate-determing-step such as 2CH3OH ? 2HCHO + 2H2. At reaction temperatures of 200oC~250oC, the selectivity of CO was smaller than 0.1%. In this way, we could reduce the toxic effect on the Pt electrode of the fuel cell.