掺杂型烧绿石La2 Sn1.7 Co0.3 O7-δ逆负载CeO2催化剂的甲烷催化燃烧性能

摘要

The inverse CeO2/La2 Sn1. 7 Co0. 3 O7-δ catalyst was prepared by sol-gel and impregnation method calcined at 900 ℃ and investigated in the methane catalytic combustion. The catalytic activity evaluated for methane combustion showed that the methane conversion temperature of T90 was 564 ℃, compared with the pure La2 Sn1. 7 Co0. 3 O7-δprepared in the same condition and mechanical mixing of La2 Sn1. 7 Co0. 3 O7-δand CeO2 , T90 decreased by 78 ℃ and 135 ℃, respectively, and the inverse CeO2/La2 Sn1. 7 Co0. 3 O7-δ catalyst not only had the excellent methane combustion activity, but also had the well thermal stability and reusable performance. The excellent performance of the inverse CeO2/La2 Sn1. 7 Co0. 3 O7-δcatalyst was represented by the characterizations of XRD, TEM, AFM, TPR, BET, XPS and Mössbauer spectra. XRD characterization showed that the inverse CeO2/La2 Sn1. 7 Co0. 3 O7-δcatalyst not only had the La2 Sn1. 7 Co0. 3 O7-δstructure, but also had the CeO2 phase, and the CeO2 had been well disperse on the La2 Sn1. 7 Co0. 3 O7-δ composite oxide; TPR indicated that the CeO2/La2 Sn1. 7 Co0. 3 O7-δ had lower reduction temperature compared to La2 Sn1. 7 Co0. 3 O7-δ, XPS and Mössbauer spectra indicated that the Sn4+ is the main valence state in the inverse catalyst, and the lattice oxygen play an important role in catalytic activity; TEM and BET tests showed that the CeO2/La2 Sn1. 7 Co0. 3 O7-δ particles had better dispersed and larger surface area than La2 Sn1. 7 Co0. 3 O7-δ. All above explained the reasons of the CeO2/La2 Sn1. 7 Co0. 3 O7-δ catalyst had excellent catalytic activity toward methane combustion.%用溶胶凝胶-浸渍法在900℃煅烧3 h后制备了烧绿石逆负载型催化剂CeO2/La2 Sn1.7 Co0.3 O7-δ,并用于甲烷催化燃烧反应,显示出较好的催化燃烧活性.催化剂还具有良好的高温热稳定性和可重复利用性能,可使甲烷转化90%的温度( T90)降到564℃,与相同条件下制备的单一烧绿石型催化剂La2 Sn1.7 Co0.3 O7-δ和La2 Sn1.7 Co0.3 O7-δ与CeO2机械混合的催化剂相比, T90分别降低78和135℃. X射线衍射结果表明,烧绿石型逆负载催化剂具有CeO2和La2 Sn1.7 Co0.3 O7-δ2种物相,在逆负载型催化剂中的CeO2比机械混合催化剂中的CeO2分散程度更好；H2程序升温还原实验也证实逆负载催化剂CeO2/La2 Sn1.7 Co0.3 O7-δ的相应3个还原峰温度均比单一烧绿石型催化剂La2 Sn1.7 Co0.3 O7-δ相应3个还原峰温度明显降低；透射电子显微镜和原子力显微镜结果表明,逆负载催化剂CeO2/La2 Sn1.7 Co0.3 O7-δ抗烧结能力强,颗粒分散均匀,粒径尺寸相应较小；穆斯堡尔谱和X射线光电子能谱结果证明逆负载催化剂CeO2/La2 Sn1.7 Co0.3 O7-δ结构中结晶相Sn4+含量较高,表面晶格氧数量较多,这是烧绿石逆负载型催化剂具有良好甲烷催化燃烧性质的主要原因.