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不添加有机模板剂,采用较廉价的硅酸钠和铝酸钠分别作为硅源和铝源,经由两步法合成粒度分布均匀且晶型较好的亚微米A型沸石。研究了经不同陈化时间后硅铝凝胶结构发生的变化及经过晶化后产物的粒径变化。结果表明:陈化时间为0~85h时,主要表现为诱导成核,在这段时期硅铝凝胶中对A型沸石成核过程有重要影响的四元环、双四元环数量显著增加,而陈化时间为85~139h主要表现为晶核的生长;随着陈化时间的延长硅铝凝胶中SiO2/Al2O3逐渐减小,且尺寸也逐渐变小;在0~85h区间,合成最终产物的平均粒径随着陈化时间延长而减小,在85h时最小,可达500nm左右;继续延长陈化时间至139h将导致小颗粒A型沸石发生团聚,且形貌也变的不规整。
Without adding organic templating agent, the cheaper sodium silicate and sodium aluminate were used as the source of silicon and aluminum respectively to synthesize the submicron zeolite A with uniform particle size distribution and good crystal form via the two-step method. The changes of structure of silica gel after different aging time and the change of particle size after crystallization were studied. The results show that when the aging time is 0 ~ 85h, the main nucleation is induced. The number of four-membered rings and double-four-membered ring which have an important influence on the nucleation process of type A zeolites during the period , While the aging time was 85 ~ 139h, which mainly showed the growth of nuclei. With the aging time, the SiO2 / Al2O3 in Si-Al gel gradually decreased and the size gradually became smaller; in the range of 0 ~ 85h, The average particle size of the final product decreases with the aging time, the smallest at 85h, up to about 500nm; continue to extend the aging time to 139h will lead to small particle zeolite A agglomeration, and morphology does not change Regular.