催化学报

催化学报 ›› 2016, Vol. 37 ›› Issue (5): 743-749.DOI: 10.1016/S1872-2067(15)61071-3

• 论文 • 上一篇    下一篇

采用射频热等离子体合成Ni-CeO2催化剂用于甲烷部分氧化

M. Y. Leea, J. S. Namb, J. H. Seoa,b   

  1. a 韩国全北国立大学应用等离子体工程系, 全罗北道 54896, 韩国;
    b 韩国全北国立大学量子系统工程系, 全罗北道 54896, 韩国
  • 收稿日期:2016-01-04 修回日期:2016-02-23 出版日期:2016-04-26 发布日期:2016-04-26
  • 通讯作者: J. H. Seo

Synthesis of Ni-CeO2 catalyst for the partial oxidation of methane using RF thermal plasma

M. Y. Leea, J. S. Namb, J. H. Seoa,b   

  1. a Department of Applied Plasma Engineering, Chonbuk National University, Jeonbuk 54896, Korea;
    b Department of Quantum System Engineering, Chonbuk National University, Jeonbuk 54896, Korea
  • Received:2016-01-04 Revised:2016-02-23 Online:2016-04-26 Published:2016-04-26
  • Contact: J. H. Seo

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摘要：

采用射频热等离子体制备了Ni含量为50 mol%的Ni-CeO2催化剂, 考察了其在甲烷部分氧化反应中的催化活性. 在催化剂制备过程中, 采用板功率为52 kVA的射频等离子体火炬将Ni(直径约5 μm)和CeO2粉末(直径约200 nm)混合物同时加热, 粉末添加速率约为120 g/h. X射线衍射和透射电镜表征结果表明, 所用前驱体形成了高结晶的CeO2载体, 其表面Ni颗粒的粒径较小(< 50 nm). 在常压、500 ℃以上、反应物中CH4:O2 = 2:1(摩尔比), 并用Ar稀释的条件下考察了所制样品的甲烷部分氧化反应性能. 结果表明, 尽管所制样品中Ni含量较高(~50 mol%), 但在550 ℃反应24 h后, 甲烷转化率为70%以上, CO和H2选择性大于90%, 有少量积碳. 然而, 在750 ℃反应24 h时, 催化剂表面形成了丝状碳, 甲烷转化率升至90%以上.

关键词: 射频热等离子体, 甲烷, 部分氧化, 镍催化剂, 氧化铈, 积碳

Abstract:

Ni-CeO2 catalysts with a nickel content of 50 mol% were prepared using RF thermal plasma, and their catalytic activities for methane partial oxidation were characterized. For the synthesis of Ni-CeO2 catalysts, a precursor containing Ni (~5-μm diameter) and CeO2 (~200-nm diameter) powders were heated simultaneously using an RF plasma at a power level of ~52 kVA and a powder feeding rate of ~120 g/h. From the X-ray diffraction data and transmission electron microscopy images, the precursor formed into high crystalline CeO2 supports with nanosized Ni particles (< 50-nm diameter) on their surfaces. The catalytic performance was evaluated under atmospheric pressure at > 500 ℃ and a CH4:O2 molar ratio of 2:1 with Ar diluent. Although the Ni content was high (~50 mol%), the experimental results reveal a methane conversion rate of > 70%, selectivities of CO and H2 greater than 90% and slight carbon coking during an on-stream test at 550 ℃ for 24 h. However, at 750 ℃, the on-stream test revealed the formation of filament-like carbons with an increased methane conversion rate over 90%.

Key words: RF thermal plasma, Methane, Partial oxidation, Nickel catalyst, Ceria, Carbon deposition