(K,Mo)Y分子筛中钼组分的EXAFS研究  

Study of Molybdenum Components in (K, Mo) Y-zeolites by EXAFS

作　　者：叶树集[1] 韦世强 孟明[1] 卞国柱[1] 姜明[1] 

机构地区：[1]中国科学技术大学化学物理系 [2]国家同步辐射实验室,合肥230026

出　　处：《Chinese Journal of Chemical Physics》2001年第1期113-118,共6页化学物理学报（英文）

基　　金：国家自然科学基金!资助项目 ( 2 98730 4 4 )&&

摘　　要：应用同步辐射ExtendedX -rayAbsorptionFineStructure (EXAFS)技术研究固态法制备的KHMoY分子筛的氧化态和硫化态样品以及硫化态KHY/MoO3样品中钼组分的局域配位环境结构 ,并与KHMoY和KHY/MoO3样品催化加氢活性结果进行对照。结果表明 ,随原子比 (K +2Mo) /Al的变化 ,钼原子周围的配位环境有显著的差异。当 (K +2Mo) /Al <1时 ,KHMoY和KHY/MoO3硫化后 ,钼组分主要以MoS2 小原子簇分散在分子筛超笼中 ;(K +2Mo) /Al >1时 ,钼组分则有两种存在环境 ,即分子筛超笼中的和分子筛外表面的钼组分。分子筛超笼中的MoS2 原子簇的催化加氢合成醇选择性较高 ;分子筛外表面的MoS2 微小颗粒的尺寸相对于超笼中的要大许多 ,其合成醇选择性较低。The local structures of the oxidic and sulfided molybdenum loaded KHMoY zeolites prepared by solid-state reaction and the sulfided mixtures of KHY/MoO 3 have been investigated by EXAFS. The alcohol synthesis of CO hydrogenation is used to characterize catalytic performance for the sulfided (K, Mo)Y catalysts which is well explained by the EXAFS results. The results indicate that the local structures of Mo(VI) species depend on the atomic ratio of (K+2Mo)/Al. At the ratio of (K+2Mo)/Al lower than the exchange capacity, i.e., 1, the molybdenum species are completely dispersed into the supercages of the zeolites as small atomic cluster of MoS 2. At the ratio of (K+2Mo)/Al lager than 1, the molybdenum species could exist in two phases, including both inside and outside of the zeolite supercages. Moreover, the size of MoS 2 located at the out-surface of the zeolite supercages is much larger than the one in the zeolite supercages. We present that MoS 2 cluster in the zeolite supercages of zeolites has a higher selectivity of alcohol synthesis for the CO hydrogenation than the MoS 2particles located at the out-surface of the zeolite supercages.

关 键 词：EXAFS 固态离子交换 Y分子筛 钼组分 同步辐射 负载型钼催化剂 结构 催化加氢活性 

分 类 号：O643.3[理学—物理化学]