高比表面积铝土矿载体的制备及在CO氧化反应中的应用

High Surface Area Bauxite:Preparation,Characterization and Application in CO Oxidation Reaction

采用水热法,对天然铝土矿进行改性,获得高比表面积的铝土矿载体(Bauxite)。用等体积浸渍法制备了不同Pt含量的Pt/bauxite和1.0%Pt/Al2O3催化剂,以CO氧化为探针反应,考察了催化剂性能。采用XRF、XRD、低温N2-物理吸附、H2-TPR以及CO-TPD等对载体和催化剂样品进行表征。结果表明:Pt/bauxite催化剂具有优异的CO氧化性能,特别是当反应温度为200℃时,催化剂1.0%Pt/bauxite的CO转化率为93.4%,而1.0%Pt/Al2O3CO转化率仅为9.4%。其原因是铝土矿含有的Fe2O3是CO氧化反应的催化剂,且Fe2O3与负载的Pt之间发生了相互作用,降低了Pt和Fe2O3还原温度,提高了对CO的吸附能力且降低了CO的脱附温度,进而提高了催化剂的CO氧化反应性能。

The hydrothermally treated bauxite with high surface area was employed as the Pt based catalyst support. A series of Pt/bauxite catalysts were prepared by incipient-wetness impregnation method. The loading of Pt was varied from 0.5wt% to 2.0wt%. The catalysts were characterized by XRF, low temperature nitrogen adsorption-desorption, XRD, H2-TPR and CO-TPD. The catalyst performance for CO oxidation reaction was also investigated. The results indicate that Pt/bauxite catalysts have excellent property for CO oxidation reaction. Especially when the reaction temperature is at 200 ℃, CO conversion rate of 1.0%Pt/bauxite is 93.2%, while 1.0Pt/Al2O3 is only 9.4%, attributed to the interaction between Pt and Fe2O3 in the modified bauxite, and the interaction could decrease the reducing temperature of Pt oxide and Fe2O3 and also improve the adsorption-desorption behavior of Pt/bauxite catalysts for CO molecule, thus increasing the CO Oxidation activity.