以晶格氧为氧源的甲烷部分氧化制合成气  

Partial Oxidation of Methane to Synthesis Gas Using Lattice Oxygen Instead of Molecular Oxygen

作　　者：李然家[1] 余长春[1] 代小平[1] 沈师孔[1] 

机构地区：[1]石油大学(北京)中国石油天然气集团公司催化重点实验室,北京102249

出　　处：《催化学报》2002年第4期381-387,共7页

基　　金：中国石油天然气集团公司石油科技中青年创新基金资助 (cx2 0 0 139)

摘　　要：采用热重分析技术在甲烷气氛下考察了储氧材料Fe2 O3 提供晶格氧的过程 ,用甲烷 /氧切换反应和在线质谱检测方法研究了以Fe2 O3 晶格氧代替气相氧用于甲烷部分氧化制合成气的可能性 .结果表明 ,Fe2 O3 在甲烷气氛下的还原过程包括Fe2 O3 →Fe3 O4 和Fe3 O4 →FeO→Fe ,甲烷被氧化为CO2 和H2 O .在 75 0℃下进行的CH4 /O2 切换反应结果表明 ,首先 ,约 2 5 %的CH4 与Fe2 O3 中的晶格氧反应 ,生成CO2 和H2 O ,然后 ,生成的CO2 和H2 O与剩余的约 75 %的CH4 在Ni/Al2 O3 催化剂上进行蒸汽重整和CO2 重整 ,从而按燃烧 重整机理实现甲烷部分氧化制合成气 .选择合适的CH4 /O2 切换条件 ,可使甲烷高转化率、高选择性地生成合成气 .The redox performance of Fe2O3, which was used as a provider of lattice oxygen, was investigated by using thermogravimetry under a methane flow. The lattice oxygen in Fe2O3 can react with CH4 to form CO2 and H2O while Fe2O3 is reduced through steps Fe2O3-->Fe3O4 and Fe3O4-->FeO-->Fe. The redox circulation technique combined with on-line quadrupole mass spectrometric analysis was used to study the feasibility of the methane oxidation to synthesis gas using lattice oxygen instead of molecular oxygen. The switching reaction between 13%O-2/He and 6.5%CH4/Ar at a flow rate of 31 ml/s and 750 degreesC was carried out in a fixed-bed reactor, in which 100 mg Fe2O3 was placed on the layer of Ni/Al2O3 Catalyst (400 mg). The results show that methane can be converted to CO and H-2. During the CH4 reaction step, about 25% methane is oxidized to CO2 and H2O by lattice oxygen from Fe2O3 and the remaining 75% methane is reformed with CO2 and H2O over the Ni/Al2O3 catalyst to produce synthesis gas. During the O-2 reaction step, lower valence iron oxide is reoxidized by molecular oxygen to its initial state. Using a suitable period of redox circulation, high conversion of methane and high selectivity to synthesis gas could be obtained over Fe2O3 and Ni/Al2O3 catalyst. These results indicate that methane can be oxidized to synthesis gas by using lattice oxygen instead of molecular oxygen through a combustion-reforming, mechanism.

关 键 词：氧源 晶格氧 甲烷 部分氧化 合成气 氧化铁 镍 氧化铝 燃烧-重整 天然气利用 负载型催化剂 

分 类 号：O643.3[理学—物理化学]