摘要
用自燃烧法制备了钙钛矿型La0 8Sr0 2 FeO3 催化剂 .用H2 TPR考察了催化剂表面的氧消耗过程 ,用程序升温表面反应(TPSR)研究了甲烷与催化剂表面氧物种的反应 ,用在线质谱脉冲反应和甲烷 /氧切换反应研究了催化剂的晶格氧选择氧化甲烷制合成气 .结果表明 ,催化剂上存在两种氧物种 ,无气相氧存在时 ,强氧化性氧物种首先将甲烷氧化为CO2 和H2 O ;而后提供的氧化性较弱的晶格氧具有良好的甲烷部分氧化选择性 ,可将甲烷氧化为合成气CO和H2 (选择性可达 95 %以上 ) .在 90 0℃下的CH4/O2 切换反应结果表明 ,甲烷能与La0 8Sr0 2 FeO3 中的晶格氧反应选择性地生成CO和H2 ,失去晶格氧的La0 8 Sr0 2 FeO3 能与气相氧反应恢复其晶格氧 .在合适的反应条件下 ,用La0 8Sr0 2 FeO3 催化剂的晶格氧代替分子氧按Redox模式实现甲烷选择氧化制合成气是可能的 .
Catalytic partial oxidation of methane to synthesis gas is a slightly exothermic, highly selective, and energy efficient process. It gives synthesis gas with a hydrogen to carbon monoxide ratio of 2∶1 that is suitable for F T and methanol synthesis. However, a process of catalytic partial oxidation of methane to synthesis gas has not yet been commercialized. Major engineering problems still exist which are the high temperature gradient and the risk of explosion, because the premixed CH 4/O 2 mixtures are within the ignition and explosion limits. Besides those, the oxygen supply by cryogenic distillation of air needs additional investment and operation expense. In order to overcome aforementioned problems, a novel process of methane partial oxidation using lattice oxygen instead of molecular oxygen to participate in methane partial oxidation to synthesis gas is proposed. The lattice oxygen from a La 0 8 Sr 0 2 FeO 3 perovskite oxide was found to be suitable for this process. In this process the La 0 8 Sr 0 2 FeO 3 oxide catalyst is circulated between two reactors. In one reactor, methane is oxidized to synthesis gas by the lattice oxygen of La 0 8 Sr 0 2 FeO 3 oxide, and in the other, the reduced La 0 8 Sr 0 2 FeO 3 oxide is re oxidized by air to restore its initial state. Since reaction occurs between methane and lattice oxygen in the absence of gas phase oxygen, this process can keep from the risk of explosion and does not need the oxygen supply. In this paper, a La 0 8 Sr 0 2 FeO 3 perovskite oxide catalyst, which is used as an oxygen provider, has been prepared by autocombustion method. XRD showed that the La 0 8 Sr 0 2 FeO 3 oxide features the crystalline phases of perovskite oxide. The evaluation of La 0 8 Sr 0 2 FeO 3 oxide was carried out in a fixed bed quartz micro reactor filled with 100 mg oxide equipped with an on line quadrupole mass spectrometer (AMTEK Q200MN) to monitor products. The quadrupole mass spectrome
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
2002年第6期549-554,共6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项目 (cx2 0 0 13 9) .
