高等学校化学学报

高等学校化学学报

• 研究论文 • 上一篇    下一篇

Cr2O3催化剂上甲烷部分氧化制备合成气

刘树强, 宋月芹, 贺德华, 李展平   

  1. 清华大学化学系, 有机光电子与分子工程教育部重点实验室, 分子催化与定向转化研究室, 北京 100084
  • 收稿日期:2008-07-21 修回日期:1900-01-01 出版日期:2009-01-10 发布日期:2009-01-10
  • 通讯作者: 贺德华

Partial Oxidation of Methane to Syngas over Cr2O3 Catalysts

LIU Shu-Qiang, SONG Yue-Qin, HE De-Hua*, LI Zhan-Ping   

  1. Innovative Catalysis Program, Key Lab of Organic Optoelectronics & Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, China
  • Received:2008-07-21 Revised:1900-01-01 Online:2009-01-10 Published:2009-01-10
  • Contact: HE De-Hua

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摘要： 分别采用柠檬酸络合法和直接分解法制备了Cr2O3催化剂, 采用XRD, BET, TPR, XPS, TEM和TGA表征了催化剂的物理化学性质, 在常压固定床石英管(内径5 mm)反应器中考察了Cr2O3催化剂对甲烷部分氧化反应的催化性能. 在500~750 ℃, V(CH4)∶V(O2)=2, 空速12×104 h-1的条件下, O2几乎完全转化, CH4转化率及H2和CO选择性随着温度的升高而增加. 700 ℃下CH4转化率及H2, CO选择性随着空速(6.0×104~24×104 h-1)的升高而增加. 在500 h稳定性实验中, 随着反应时间的延长, CH4转化率及H2, CO选择性缓慢下降, XRD, TEM和BET结果表明, 催化剂的活性下降与烧结和团聚有关, TGA分析表明催化剂具有良好的抗积炭性. 通过CH4脉冲反应, 推测在反应过程中CO, H2, CO2和H2O是直接生成的.

关键词: 三氧化二铬, 甲烷部分氧化, 合成气, 晶格氧, 脉冲反应

Abstract: Cr2O3 catalysts were prepared by citric acid method and direct decomposition of Cr(NO3)3. The POM reactions were carried out in a flow-type fixed bed micro reactor(quartz tube, i.d. 5 mm) at atmospheric pressure. The influences of reaction temperature and space velocity on POM reaction were investigated. The results show that the conversion of methane, selectivities of CO and H2 increase with the reaction temperature(500-750 ℃) and the oxygen is almost exhausted under the conditions of GHSV=12×104 h-1 and V(CH4)∶V(O2)=2. Furthermore, the conversion of methane, selectivities of CO and H2 increase with the GHSV(6.0×104-24×104 h-1) under the conditions of V(CH4)∶V(O2)=2 at 700 ℃. In 500 h on stream, the conversion of methane, selectivities of CO and H2 decrease slowly with the time on stream and the oxygen is almost exhausted under the conditions of GHSV=12×104 h-1 and V(CH4)∶V(O2)=2 at 700 ℃. The results of X-ray diffraction(XRD), TEM and BET specific surface area showed that the sinter of Cr2O3 catalyst may be responsible for the deactivation of Cr2O3 catalyst. Methane pulse reaction was carried out and the results indicated that the POM mechanism over Cr2O3 catalyst may be Mars-Van Krevelen mechanism.

Key words: Cr2O3, Partial oxidation of methane, Syngas, Lattice oxygen, Pulse reaction

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