Kinetic isotope effects and mechanism of biomimetic oxidation of methane and benzene on FeZSM-5 zeolite
Kinetic isotope effects and mechanism of biomimetic oxidation of methane and benzene on FeZSM-5 zeolite
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DOI：
10.1016/s1381-1169(97)00051-4
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发表时间：
1997-08-29
影响因子：
--
通讯作者：
Panov, GI
中科院分区：
文献类型：
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作者：
Dubkov, KA;Sobolev, VI;Panov, GI
早些时候，稳定在ZSM-5沸石基质中的铁络合物被证明在N2O分解时产生一种新形式的表面氧(称为α-氧)。α-氧对单加氧酶(MO)中的氧表现出非常高的反应活性，并模仿其在室温下选择性氧化碳氢化合物的独特能力。本文报道的动力学同位素效应(KIE)测量揭示了MO和模型之间的其他相似之处。根据温度的不同，α-氧氧化甲烷的Kie值在1.9到5.5之间。对于苯的氧化，Kie值为1.0。这表明甲烷的生物氧化和化学氧化都涉及速率限制的C-H键断裂，而与苯的反应可能受到环氧型中间体的形成的限制。假定的活性中心结构和氧化机理的一些特征使人们认为FeZSM-5-N2O体系是一种新的成功的甲烷单加氧酶模型。
Earlier, iron complexes stabilized in a ZSM-5 zeolite matrix have been shown to produce a new form of surface oxygen (called alpha-oxygen) upon decomposition of N2O. alpha-Oxygen exhibits a very high reactivity typical for oxygen of monooxygenases (MO) and mimics its unique ability in selective oxidation of hydrocarbons at room temperature. Kinetic isotope effect (KIE) measurements reported here reveal additional similarities between MO and the model. Depending on the temperature, the value of KIE for oxidation of methane with alpha-oxygen ranges from 1.9 to 5.5. For the oxidation of benzene the value of KIE is 1.0. This indicates that both biological and chemical oxidation of methane involves a rate limiting C-H bond cleavage, whereas the reaction with benzene is probably limited by the formation of an epoxy-type intermediate. The assumed structure of the active sites as well as some features of the oxidation mechanism allow one to consider FeZSM-5-N2O system as a new and successful model for methane monooxygenase.