摘要
在Ｍｎ２Ｏ３－Ｎａ２ＷＯ４／ＳｉＯ４催化剂上的甲烷氧化偶联反应可用Ｒｉｄｅａｌ－ｒｅｄｏｘ机理描述，它包括均相及多相两个步骤．甲基自由基的生成是一个多相过程（表面反应），Ｃ２烃的生成是一个均相过程（气相反应）．催化剂的活性同氧化速率（ｋ１）和ＣＨ４与表面氧种的反应速率（ｋ２）有关，Ｃ２烃的选择性与甲基自由基氧化速率常数和甲基自由基偶联速率常数的比值（ｋ／ｋ４）有关，这些常数均可从实验中求得．
he oxidative coupling of methane over 2%Mn2O3-5%Na2WO4/SiOcatalyst can be explained by using Rideal-redox mechanism, which includes heterogeneous and homogeneous steps. The production of gaseous· CH3would be a heterogeneous process (surface reaction), and the production of C2 hydrocarbons would be a homogeneous process (gas phase reaction). The reactivity is related to the rate of oxidation on the catalyst surface (k1) and the rate of the reaction between surface oxygen and CH4(k2), and the selectivity for C2 hydrocarbons is related to the ratio of methyl oxidation and methyl coupling (h/k4). The constants are easily obtained from the flow experiments.
基金
国家自然科学基金
关键词
甲烷
氧化偶联
钨酸钠
二氧化硅
催化剂
kinetics, methane, oxidative coupling, manganic oxide, sodium tungstate, silica, supported catalyst
