脱铝方法对富硅丝光沸石性质的影响

THE INFLUENCE OF DEALUMINATION METHODS ON THE PROPERTIES OF MORDENITES

本文用酸浸取,水蒸汽处理加酸浸取和(NH_4)_2SiF_6类质同晶取代三种不同方法制备了Si/Al比为6—15左右的富硅丝光沸石样品,并且用多种实验手段测定了它们的相对结晶度,羟基空穴摩尔分数,晶胞参数,红外反对称伸缩振动频率,热稳定性和水热稳定性,表面酸性和催化活性。实验结果表明脱铝方法对富硅丝光沸石的性质有很大的影响,不同的脱铝方法得到的沸石样品在许多方面有显著的差别。文中对此进行了详细的描述,并对产生这些差别的结构因素讲行了讨论。

High silica mordenites with Si/Al ratios in the range of 6-15 were prepared by acid leaching, steaming plus acid leaching and isomorphous substitution with (NH_4)_2SiF_6 methods. The relative crystallinity, hydroxyl nest mole fraction, unit cell parameters, infrared asymmetric stretch frequency, thermal and hydrothermal stability, surface acidity and catalytic activities of the mordenites were investigated with various techniques. It has been found that the properties of the mordenites depend strongly on the preparation methods. Samples prepared with various dealumination procedures show significant difference in many aspects. These differences were described in detail and explained in relation to structural changes of the zeolites.