Effect of ZrO2 promoter on the catalytic activity for CO methanation and its adsorption performance of the Ni/SiO2 catalyst
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摘要: 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。
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关键词:
- Ni/SiO2催化剂 /
- ZrO2助剂 /
- CO甲烷化 /
- 吸附
Abstract: 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/ZrO2SiO2 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.-
Key words:
- Ni/SiO2 catalyst /
- ZrO2 promoter /
- CO methanation /
- adsorption
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