论文部分内容阅读
采用共沉淀法合成了镍镁铝水滑石(NiMgAl-layered double hydroxides,NiMgAl-LDHs),将其分别在500,550,600℃焙烧,得到镍镁铝复合氧化物。用X射线粉末衍射和氢气程序升温还原技术对层状水滑石前躯体和衍生复合氧化物的结构与还原特性进行表征,并通过质谱对NiMgAl-LDHs原位还原过程进行了分析。结果表明NiMgAl-LDHs原位还原过程包括3个步骤:首先,水滑石层间水分子脱除;其次,层板中的Ni2+被直接还原为Ni0,同时水滑石发生羟基脱水和碳酸根脱除得到NiMgAl(O);最后,NiMgAl(O)中Ni在高温下被还原。NiMgAl-LDHs通过原位氢气还原活化得到的镍基金属负载型催化剂,相比传统方法(先焙烧后还原)具有更高的制氢催化活性。
NiMgAl-layered double hydroxides (NiMgAl-LDHs) were synthesized by co-precipitation method, and calcined at 500, 550 and 600 ℃ respectively to obtain nickel-magnesium aluminum composite oxide. The structure and reduction characteristics of layered hydrotalcite precursors and derivatized composite oxides were characterized by X-ray powder diffraction and hydrogen temperature-programmed reduction. The in situ reduction of NiMgAl-LDHs was analyzed by mass spectrometry. The results show that the NiMgAl-LDHs in-situ reduction process consists of three steps: firstly, the water molecules are removed from the interlayer of the hydrotalcite; secondly, the Ni2 + in the laminate is directly reduced to Ni0, and the hydroxyl dehydration and carbonate removal of the hydrotalcite are obtained NiMgAl (O); Finally, Ni in NiMgAl (O) is reduced at high temperature. NiMgAl-LDHs obtained by in situ hydrogen reduction of activated nickel-based metal-supported catalyst, compared with the traditional method (first calcined reduction) has a higher hydrogen catalytic activity.