ZnO催化作用下甲醇与碘甲烷反应的机理

为了探讨甲醇与碘甲烷反应的机理，以甲醇和碘甲烷为反应物，在催化剂ZnO的作用下制备了2,2,3 三甲基丁烷(Triptane)，考察了CH3OH与CH3I摩尔比对反应的影响；通过考察替代反应物(醇、碘代烃)的种类对反应产物分布的影响，分析反应中间体、产物的形成机理。采用能谱仪(EDS)和热重(TG)对反应前后催化剂的组成进行分析，并探讨甲醇和碘甲烷在ZnO作用下催化反应的机理。结果表明，在n(CH3OH)∶n(CH3I)=1∶1、反应温度200 ℃下反应3 h，CH3I和CH3OH的转化率分别为595%和495%，烃类物质的总质量产率为836%，其中Triptane在油相产物中的质量分数约为35%。反应机理研究表明：该反应的催化剂为碘甲烷与氧化锌反应生成的碘化锌，而含羟基反应物与催化剂作用形成烷氧基，是反应的活性中间体。

Reaction Mechanism of Methanol With Methyl Iodide Over ZnO Catalyst

Reaction mechanism of CH3OH with CH3I to 2,2,3 trimethylbutane (triptane) over ZnO catalyst was studied, and the effects of CH3OH/CH3I mole ratio on catalytic performance were investigated. The formation mechanisms of reaction intermediates and products are discussed through analyzing the changes of products distribution by using different alcohols and alkyl iodide. The compositions of fresh and spent catalysts were characterized by EDS and TG methods. Meanwhile, the catalytic performance of ZnO catalyst was evaluated. It is found that the conversion ratios of CH3I and CH3OH are 595% and 495% respectively at 200 ℃ for 3 h with a CH3OH/CH3I mole ratio of 1∶1. Under such reaction conditions, the yield of hydrocarbons is 836%. The content of triptane reaches up to 35% in oil phase. It is confirmed that the ZnI2, produced from CH3I and ZnO, is the actual active site for this transformation, with the formation of alkoxy compound derived from alcohols as key reactive intermediate.