论文部分内容阅读
采用液相法室温制备A型沸石,利用X射线衍射、扫描电子显微镜、红外光谱等考察晶化时间和凝胶中n(Al_2O_3)/n(SiO_2)比对沸石的成核与晶体生长过程的影响。结果表明:晶化120 h时,反应体系以成核作用为主;120~156 h是A型沸石晶体的快速生长期;晶化时间为168 h时,合成产物具有较好结晶度。与常规95℃制备A型沸石相比,室温合成抑制了杂相的形成,延长晶化时间没有诱发羟基方钠石生成。同时,室温合成制备的样品,粒度明显减小,出现明显的附聚现象。n(Al_2O_3)/n(SiO_2)在0.35~0.80时,样品均为单相的A型沸石,提高n(Al_2O_3)/n(SiO_2)导致晶粒细化。n(Al_2O_3)/n(SiO_2)为0.35、0.45、0.60和0.80时,样品的平均粒径分别为385、329、260和192 nm。
The zeolite A was prepared by liquid phase method at room temperature. The crystallization time and the ratio of n (Al 2 O 3) / n (SiO 2) in zeolite were investigated by X-ray diffraction, scanning electron microscopy and infrared spectroscopy. influences. The results show that the nucleation is the main reaction system at 120 h crystallization and the rapid growth of A zeolite at 120-156 h. The crystallinity of the synthesized product is good at the crystallization time of 168 h. Compared with the conventional A zeolite prepared at 95 ℃, the synthesis at room temperature inhibited the formation of heterophase, prolonging the crystallization time did not induce the hydroxy-sodalite formation. At the same time, the samples prepared by room temperature synthesis, the particle size was significantly reduced, the apparent agglomeration phenomenon. When n (Al_2O_3) / n (SiO_2) is 0.35 ~ 0.80, the samples are all single-phase zeolite A, and grain refinement is enhanced by increasing n (Al_2O_3) / n (SiO_2). The average particle sizes of the samples were 385, 329, 260 and 192 nm for n (Al 2 O 3) / n (SiO 2) 0.35, 0.45, 0.60 and 0.80, respectively.