新型固体强碱KNO_3/Al_2O_3的碱性  

BASIC PROPERTIES OF NEW SOLID STRONG BASES DERIVED FROM Al_2O_3 SUPPORTED KNO_3

作　　者：朱建华[1] 王英[1] 淳远[1] 

机构地区：[1]南京大学化学系

出　　处：《催化学报》1997年第6期498-502,共5页

基　　金：国家教委留学回国人员科研资助;南京大学分析中心测试基金

摘　　要：剖析了不同ＫＮＯ３负载量在Ａｌ２Ｏ３上的分散及分解，测定了ＫＮＯ３／Ａｌ２Ｏ３的碱量及碱强度．负载量低于其单层分散阈值时可被均匀分散，碱强度（Ｈ－）为１８４；高于单层分散阈值时，只有７％的ＫＮＯ３与Ａｌ２Ｏ３表面相互作用而分散并在温和条件下分解，大部分ＫＮＯ３在８７３Ｋ活化才分解并重新分布，形成Ｋ２Ｏ类物种的多层叠合结构，产生碱强度为２７０的超强碱位．Dispersion and decomposition of KNO_3 loaded on Al_2O_3 were examined by means of XRD and XPS. The basicity of KNO_3/Al_2O_3 was evaluated by using CO_2TPD and titration methods. All of the KNO_3 loaded on Al_2O_3 can be well dispersed and has a basic strength (H-) of 184 when the loading of KNO_3 is below the monolayer dispersion threshold. However, when the loading of KNO3 is above the threshold, only about 7% of KNO3 can be dispersed through the interaction with Al2O3 support and decomposed in a mild pretreatment such as evacuation at room temperature, while a lot of the undispersed KNO3 located in the pores of Al2O3 forms a new phase such as K2[Al(NO3)]5 . Both the residual KNO3 and K2[Al(NO3)]5 decompose during evacuation at 873 K, and potassium ions migrate from the inner to the external surface of Al2O3 during the evacuation process. Consequently, several layers of basic materials such as K2O overlap on the Al2O3, and result in some superbasic sites with a basic strength (H-) of 270. These superbasic basic sites exhibit high catalytic activity in the cisbutene2 isomerization at 273 K, and catalyze cistrans isomerization besides double bond isomerization of cisbutene2 at 273 K.

关 键 词：顺丁烯 异构化 硝酸钾 氧化铝 固体超强碱 

分 类 号：O643.36[理学—物理化学] O623.121[理学—化学]