Cu(Al)O复合物表面酸碱性质的微量吸附量热研究  

MICROCALORIMETRIC STUDIES OF SURFACE ACIDITY AND BASICITY OF Cu(Al)O COMPOSITE OXIDES

作　　者：李大塘[1] 郭军[1] 邓谦[1] 邓立元[1] 罗娟[1] 

机构地区：[1]湘潭师范学院化学系,湖南湘潭411201

出　　处：《化学研究与应用》2001年第2期141-144,共4页Chemical Research and Application

基　　金：湖南省教育厅基金! ( 0 0C2 42 );湖南省自然科学基金! ( 98JJY2 0 5 7)资助项目

摘　　要：673K分解Cu/Al物质的量比分别为 0 .5、1和 2的Cu Al水滑石转化为Cu(Al)O复合物。XRD测定仅显示CuO物相 ,表明组成成分较均一。微量吸附量热法测定Cu(Al)O复合物表面酸碱中心的强度和数量 ,给出了吸附分子CO2 /NH3 的吸附曲线。量热结果展示 ,样品的酸中心强度顺序是 :0 .5CAO >CAO >2CAO ,而碱中心强度顺序是 :0 .5CAO <CAO <2CAO。显然 ,样品的酸性 (碱性 )随着Al(Cu)含量的提高而逐渐增强。研究表明 ,样品的NH3 和CO2 起始吸附热与其Sanderson电负性线性相关。A series of copper aluminium hydrotalcites,with Cu/Al ratios by weight 0.5、1 and 2,was synthesized by using a sodium carbonate solution as the precipitating reagent through the coprecipitaion method.After calcination at 673K,the hydrotalcites were converted into Cu(Al)O composite oxides,showing only the patterns of CuO by X ray diffraction measurements.Microcalorimetric measurements of NH 3 and CO 2 adsorptions were used to determine the strength of acid and base sites on copper aluminium composite oxides,and adsorption curves were given coneurently.The results revealed that the acidity sequence is 0.5CAO>CAO>2CAO,while basicity order is 0.5CAO<CAO<2CAO.It is obvious that the increase of the Cu/Al amount of substance ratios enhanced the surface basicity while reduced the surface acidity of the composite oxides.The initial heats of NH 3 and CO 2 adsorption were found to be proportional to Sanderson electronegativities of the samples.

关 键 词：微量吸附量热 铜铝复合氧化物 铜-铝水滑石 表面酸碱性 催化剂 

分 类 号：O643.36[理学—物理化学]