超细镍基催化剂的CH_4-CO_2重整反应性能Ⅲ制备方法对催化剂吸附CO_2性能的影响

CH_4 Reforming with CO_2 over Superfine Ni based Catalysts Ⅲ. Effects of Adsorption of CO_2 on Structure of Catalyst

采用溶胶 -凝胶法和超临界干燥技术 ,制备了气凝胶超细氧化铝载体、超细二元 (Ni O- Al2 O3)和三元(Ni O- L a2 O3- Al2 O3)催化剂 ,同时以超细氧化铝载体浸渍镍盐的二元催化剂和普通氧化铝浸渍的镍镧铝三元催化剂作为对比 .通过 CO2 - TPD实验及 XRD、XPS和 IR技术表征 ,考察了制备方法和氧化镧改性对催化剂吸附二氧化碳能力的影响 .结果表明 ,超细样品的吸附能力明显高于浸渍型催化剂 ,具有明显的纳米粒子效应 .L a2 O3的加入 ,提高了强碱中心数 ,使催化剂的吸附能力显著增强 ,且不受制备方法的影响 .还原后的镍物种吸附 CO2 后 ,与载体之间的相互作用被消弱 。

The adsorption of CO 2 and its effect on nickel based catalysts prepared by sol gel method and supercritical drying technique or ordinary wet impregnation and thermal drying were carefully investigated by means of CO 2 TPD experiment, XRD, XPS and techniques. The superfine alumina aerogel support and NiO Al 2O 3, NiO La 2O 3 Al 2O 3 aerogel catalysts show very high adsorption capacity of CO 2 comparing with ordinary ones, which is thought to be beneficial to their activity for CH 4 CO 2 reforming and the resistance to carbon deposition. In addition, the addition of La 2O 3 is very useful for increasing the active sites due to its strong interaction with CO 2. The reduced Ni species can be reoxidized into oxidized state with large particle size during the adsorption of CO 2, at the same time, the interaction of metal with support has been substantially weakened.