摘要
采用浸渍法制备了Ni/MgO与Ni/O-D(氧化金刚石)催化剂,分别研究了反应温度和空速对甲烷催化裂解转化率的影响,并利用XPS、SEM、EDS等测试技术对催化剂进行了表征。结果表明,33Ni/O-D和41Ni/MgO分别在500与650℃能长时间维持其催化活性,前者在150min内的甲烷转化率>8%,后者则在120min内的甲烷转化率>25%;甲烷初始转化率随裂解反应温度升高而增大,但温度过高导致催化剂迅速失活;降低空速有利于提高甲烷的转化率,但却会降低氢气产量;甲烷裂解生成的碳产物形貌取决于载体和催化反应条件,较低温度(500和550℃)下,Ni/O-D表面的裂解碳呈现出纤维状,在650℃以上则表现为板结颗粒堆积并将Ni完全覆盖,但该温度下的Ni/MgO表面仍能形成碳纤维,并随空速降低存在直径增加的趋势。
Ni/MgO and Ni/O-D （oxidized diamond ） catalysts were prepared by wetness impregnation method. The effects of reaction temperature and space velocity of methane on the methane conversion were investigated in a fixed-bed. The surface area, structure and morphology were characterized with BET, XPS, SEM, EDS techniques. The results show that the conversion of methane was above 8% within 150 min（t = 500℃ ） in the presence of 33Ni/O-D catalyst and higher than 25% within 120 min （ t = 650 ℃ ） in the presence of 41Ni/MgO catalyst. The initial conversion increases with the increasing temperature of the decomposition reaction, but their catalytic activities decrease rapidly if the temperature is too high. Decreasing the space velocity of methane is propitious to improving the methane conversion, but not favorable for the hydrogen yield. The appearance of carbon resulted from the methane decomposition lies on the support type and the condition of catalytic reaction. It showed fiber shape on the surface of Ni/O-D at the relatively lower temperature such as 500 ℃ and 550 ℃ , but grain shape stacked on and overlaid on the surface of the metal nickel at 650 ℃. The carbon fiber can form on the Ni/MgO surface at 650 ℃ and the diameter of the carbon fiber increases with the decreasing space velocity.
出处
《应用化学》
CAS
CSCD
北大核心
2008年第2期245-250,共6页
Chinese Journal of Applied Chemistry
关键词
甲烷
催化
裂解
氢气
碳纳米纤维
methane, catalytic decomposition, hydrogen, carbon nanofiber
