摘要
采用浸渍法制备了不同La掺杂量的Ni-SiO2催化剂,研究了La掺杂量对Ni-SiO2催化剂的Ni活性金属粒径、还原性能、甲烷催化裂解寿命以及反应后生成碳纤维的影响。结果表明:La、Ni物质的量比由0增长至0.3时,Ni-SiO2催化剂的寿命显著提高,而当La、Ni物质的量比由0.3增长至0.6时,催化剂寿命在一定程度上略有降低;La、Ni物质的量比由0增长至0.6时,还原后催化剂Ni金属的平均粒径从26.43nm不断降低至10.57nm。不同La掺杂量Ni-SiO2催化剂甲烷催化裂解过程中Ni金属平均粒径变化趋势明显不同,n(La)∶n(Ni)=0的Ni-SiO2催化剂随反应进行Ni金属平均粒径不断降低,而n(La)∶n(Ni)=0.3的Ni-SiO2催化剂随反应进行Ni金属平均粒径则不断升高。碳纤维形态受掺La掺杂量影响较大,随La、Ni物质的量比由0增长至0.3,反应过程中生成的碳纤维管径变粗,而随La、Ni物质的量比由0.3增长至0.6,碳纤维变短。
Ni-SiO2 catalysts doped with different contents of La were prepared by impregnation method. The effects of La contents doped in Ni-SiO2 on the Ni particle size, the reducibility of catalysts, the catalytic performance of methane decomposition and the structure of carbon filaments were studied. The results demonstrate that the lifespan of Ni-SiO2 increased continuously when the molar ratio of La/Ni increased from 0 to 0. 3, while as the molar ratio of La/Ni increased from 0. 3 to 0. 6, a downward trend appeared. The Ni particle size decreased from 26. 43nm to 10.57nm when the molar ratio of La/Ni increased from 0 to 0. 6. The changing tendency of Ni particle size of Ni-SiO2 during methane decomposition was different for Ni-SiO2 with different the molar ratio of La/Ni. The Ni particle size of Ni-SiO2 （n（La） ： n （Ni） = 0） decreased continuously as methane decomposition proceeded, however, the Ni particle size of Ni-SiO2 （n（La） ： n（Ni）=0. 3） increased continuously as the reaction proceeded. The structure of the carbon filaments generated during methane decomposition strongly depended on the molar ratio of La/Ni： as the La/Ni in- creased from 0 to 0. 3, the carbon filaments turned thicker, while as the the molar ratio of La/Ni increased from 0. 3 to 0.6, the carbon filaments turned shorter.
基金
国家磁约束核聚变能研究专项资助(2011GB111005)
