单分散硅溶胶前体制备的Ni/SiO_2催化剂裂解甲烷制氢

采用以水玻璃为原料合成的单分散硅溶胶 ,并以此为前体制备了担载Ni/SiO2 催化剂 ,研究了该催化剂催化甲烷裂解制氢的性能。评价结果表明 ,该催化剂具有好的催化裂解甲烷活性 ,甲烷转化率和产氢量与反应温度密切相关。XRD结果表明 ,催化裂解甲烷后催化剂表面积炭表现出类石墨结构的衍射峰。TEM和TGA结果显示 ,不同温度下产生的积炭形式不同 ,且积炭的氧化温度也不相同。 5 0 0℃时 ,积炭形式主要为柱状纤维 ;6 0 0℃或者 70 0℃的条件下 ,可以得到碳纳米管 ;在80 0℃时 ,Ni颗粒迅速被表面积炭所覆盖并团聚

Hydrogen Production via Methane Decomposition over Ni/SiO2 Catalysts

Hydrogen production via methane decomposition was investigated over a Ni/SiO_2 catalyst using monodisperse silica sol prepared from water glass as support precursor. The results show that the catalyst reveals excellent catalytic activity and the conversion of methane and yield of hydrogen are dependent on the crackingtemperatures of methane. XRD patterns of deposited carbons result in the similar phase of graphite. TEM and TGA results indicate the species and oxidation of deposited carbons are different at various temperatures: cylinder carbon fibers are also formed at 500℃, nanotubes are formed at 600℃ or 700℃, and the catalyst loses its activity quickly due to Ni particles covered by deposited carbon rapidly at 800℃.