ZrO2助剂对Ni/SiO2催化剂CO甲烷化催化活性及其吸附性能的影响

采用连续流动微反装置和原位漫反射红外光谱法考察了Ni/SiO₂及添加ZrO₂助剂的Ni/ZrO₂-SiO₂催化剂CO甲烷化催化活性和吸附性能。结果表明，在CO体积分数 1%、空速 5000h^-1、常压的反应条件下，200℃时Ni/ZrO₂-SiO₂催化剂可将CO完全转化。而相同反应条件下Ni/SiO₂催化剂上CO的转化率仅为35%，直至270℃时方可将CO完全转化。由此可见，ZrO₂助剂的添加明显提高了Ni/ZrO₂-SiO₂催化剂的CO甲烷化催化活性。同时，ZrO₂助剂的添加显著提高了Ni/ZrO₂-SiO₂催化剂对CO的吸附能力，H₂存在时可通过在较低温度时形成较多的桥式羰基氢化物来提高Ni/ZrO₂-SiO₂催化剂的CO甲烷化催化活性；CO甲烷化反应条件下，Ni/SiO₂和Ni/ZrO₂-SiO₂催化剂上C-O键的削弱和断裂是经由羰基氢化物 多氢羰基氢化物的途径，而不是经由C-O键的直接断裂途径。

Effect of ZrO2 promoter on the catalytic activity for CO methanation and its adsorption performance of the Ni/SiO2 catalyst

The catalytic activities for CO methanation and adsorption performances of the Ni/SiO₂ and Ni/ZrO₂-SiO₂ catalysts were investigated by a continuous flowing microreactor apparatus and in-situ diffuse reflectance fourier transform infrared spectroscopy. The results showed that CO was completely transformed at 200℃ under the reaction conditions: CO 1%、GHSV 5000h^-1 and an atmosphere pressure over the Ni/ZrO₂-SiO₂ catalyst, while under the same reaction conditions the CO conversion was only 35% and CO was not completely transformed until 270℃ over the Ni/SiO₂ catalyst, which suggested the catalytic activity of the Ni/ZrO₂ SiO₂ catalyst increased with the addition of ZrO₂ promoter. Meanwhile, the addition of ZrO₂ promoter enhanced the adsorption capacity of the Ni/ZrO₂-SiO₂ catalyst for CO, and that in the presence of H₂ a larger amount of bridged carbonyl hydride formed over the Ni/ZrO₂-SiO₂ catalyst at lower temperature, resulting in the increase of its catalytic activity. In CO methanation reaction, the breaking of C-O bond over those catalysts was via multi-hydrogen carbonyl hydride rather than via direct breaking.