CaO对CaO－BaCO_3／La_2O_3促进乙烷化脱氢性能的影响

The Influence of CaO over CaO-BaCO_3/La_2O_3 Catalyst System for OXidative Dehydrogenation of Ethane

ＢａＣＯ＿３／Ｌａ＿２Ｏ＿３中用离了半径更接近Ｌａ￣（３＋）的Ｃａ￣（２＋）取代部分Ｂａ￣（２＋），制成（Ｃａ＿ｙＢａ＿（８－ｙ））Ｌａ＿２Ｏｗ，以增大低价离子在Ｌａ＿２Ｏ＿３中的溶解度，增加结构缺陷，在６２０～６８０℃内，其乙烷氧化脱氢（ＯＤＥ）的催化活性随Ｃ￣（２＋）的增加而持续上升，乙烯的选择性则单调下降。ＸＲＤ和ＸＰＳ检测证实，该体系于反应条件下形成的ＣａＢａ（ＣＯ＿３）＿２混合碳酸盐在表面上于较低的温度下分解为氧化物或过氧化物，这是它有较高ＯＤＥ催化活性的又一原因。这些构成了探索高性能乙烷氧化制乙烯催化剂的基础。

In order to increase the solubility of the cation with lower valency in host oxideand provide higher concentration fo anionic vacanciee,the subetitution of Ba￣(2+) over (Ca_yBa_(8-y))La_2Oweatalyst system with Ca￣(2+) was carried out, since the ionic radii of Ca￣(2+) and La￣(3+) were comparable. Asthe results,between the temperature range of ODE reaction(620～680℃),the conversion of ethanefor oxidative dehydrogenation was enhanced,while the selectivity of ethene was declined monotonous-ly as the concentration of Ca￣(2+) increased.with XRD and XPS analysis,it had determined that themixed carbonate CaBa(CO_3)_2 which formed under ODE reaction conditions, decomposed into corre-spondent oxides or peroxides,and it was the another reason for the CaO-BaCO_3/La_2O_3 having highercatalytic activity. These conclusions constituted the fundamental basic to search suitable catalyst sys-tem with higher ethene selectivity and /or higher conversion of ethane.