KNO_3/Al_2O_3和K_2CO_3/Al_2O_3的强碱性研究  

Exploration on the Unusually Strong Basic Properties of KNO_3/Al_2O_3 and K_2CO_3/Al_2O_3

作　　者：朱建华[1] 王英[1] 淳远[1] 胡玉海 

机构地区：[1]南京大学化学系

出　　处：《Chinese Journal of Chemical Physics》1998年第2期178-183,共6页化学物理学报（英文）

基　　金：国家教委留学回国人员科研资助;南京大学分别中心测试基金

摘　　要：采用ＣＯ２－ＴＰＤ及Ｈａｍｍｅｔ指示剂法测定了ＫＮＯ３／Ａｌ２Ｏ３及Ｋ２ＣＯ３／Ａｌ２Ｏ３样品的碱量和碱强度。当ＫＮＯ３、Ｋ２ＣＯ３的负载量低于其单层分散阈值时，能在Ａｌ２Ｏ３上均匀分布并产生强度（Ｈ－）为１８．４的强碱位；高于其单层分散阈值后则能生成强度（Ｈ－）为２７．０的超强碱位。Dispersions of KNO_3 or K_2CO_3 loaded on Al_2O_3 was examined by means of XRD and XPS,while the basic properties of these unusually strong solid bases,derived from the Al_2O_3 supported KNO_3 or K_2CO_3,were evaluated by use of CO_2-TPD,titration and the isomerization of butene at 0℃. If the amount of KNO_3 or K_2CO_3 loaded is below its monolayer dispersion threshold on Al_2O_3,all of them can be well disersed and consequently a basic strength(H-) of 18.4 is produced.When the amount loaded is above the threshold,however,a lot of KNO_3 seems to locate in the pore of Al_2O_3 and a new phase such as K_2 Al(NO_3)_5 is formed.Evacuation at 600℃caused not only the decomposition of residual KNO_3 and K_2 Al(NO_3)_5 ,but also the migration of potassium species from the inner to the external surface of Al_2O_3.As a result,sever layers of basic species such as K_2O may overlap on the Al_2O_3,because the KNO_3 dispersed and decomposed has exceeded the monolayer threshold.It is important to find that some superbasic sites iwth a basic strength(H-)of 27.0 are formed on both 20%K_2CO_3/Al_2O_3 and 29%KNO_3/Al_2O_3 smples.Based on the advantages in preparation and storage,these new unusual strong solid bases are expected to be used as the nwe basic catalysts in industrial.

关 键 词：固体 超强碱 催化剂 硝酸钾 碳酸钾 氧化铝 

分 类 号：O643.36[理学—物理化学]