Cu(Al)O复合物表面酸碱性质的微量吸附量热研究

673K分解Cu/AI物质的量比分别为0．5、1和2的Cu-AI水滑石转化为Cu(AI)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(AI)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AI(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。

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

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 NH3 and CO2 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 NH3 and CO2 adsorption were found to be proportional to Sanderson electronegativities of the samples.