Acta Phys. -Chim. Sin. ›› 2009, Vol. 25 ›› Issue (11): 2261-2269.doi: 10.3866/PKU.WHXB20091101

• ARTICLE • Previous Articles     Next Articles

Al2O3-Modified Fe2O3 Based Gold Catalysts with Good Thermal Stability

LIU Rui-Hui, ZHANG Cun-Man, MA Jian-Xin   

  1. School of Environmental Science and Engineering, Tongji University, Shanghai 200092, P. R. China|Clean Energy Automotive Engineering Center, Tongji University, Shanghai 201804, P. R. China|School of Automotive Studies, Tongji University, Shanghai 201804, P. R. China
  • Received:2009-05-18 Revised:2009-08-05 Published:2009-10-28
  • Contact: MA Jian-Xin E-mail:jxma@tongji.edu.cn

Abstract:

Al2O3-modified Fe2O3 based gold catalysts with good thermal stability were prepared by co-precipitation and deposition-precipitation method. Characterization techniques, such as transmission electron microscope (TEM), X-ray diffraction (XRD), N2 adsorption-desorption, and thermogravimetry-differential scanning calorimetry (TG-DSC), were used to investigate the structures, and surface morphologies of the catalysts. TEM results showed that after calcination at 500 ℃ the size distribution of the gold particles in the catalyst without Al2O3 doping was wide, the average diameter of the gold particles was about 7.0 nmand the size of the support particles ranged from 50 to 100 nm. However, the size distribution of the gold particles in the Al2O3-doped catalysts was narrow and the average diameter of the gold particles was around 5.0 nm. The Al2O3-doped Fe2O3 based Au particle size remained in a range of 30-50 nm, which is smaller than that of the Fe2O3 grains that were not doped with Al2O3. N2 adsorption-desorption measurements showed that Al2O3 doping resulted in a stable mesoporous structure for the catalysts and remained a higher specific surface area, which promoted the thermal stability of the support. XRD and TG-DSC results indicated that Al2O3 doping retarded the crystallization of the support and consequently inhibited the growth of gold particles during high-temperature calcination. Low temperature CO oxidation was used as a probe reaction to evaluate the catalytic activity. Even when calcined at 500 ℃ for 12 h, the catalyst with Al2O3 doping achieved complete CO conversion at 26.7 ℃ while the lowest temperature of the complete CO conversion (T100) of the catalyst without Al2O3 doping was as high as 61.6 ℃. Apparently, thermal stability is enhanced considerably by Al2O3 doping.

Key words: Nano-structured gold catalyst, Ferric oxide support, Thermal stability, Al2O3, CO oxidation at low-temperature

MSC2000: 

  • O643