【摘要】 以沉淀二氧化硅、氢氧化铝为硅源和铝源、氢氧化钾和氢氧化钠为碱源,在水热条件下合成了L沸石,研究了在加入L沸石导向剂情况下L沸石的晶化相区及随合成条件的变化.实验发现硅铝比n(SiO2)/n(Al2O3)等于14时,不加L沸石晶化导向剂,在150℃晶化时不能得到纯的L沸石,产物为无定形或主要为W沸石.加入L沸石导向剂容易在低硅铝比时合成纯净的L沸石,适宜的L沸石合成条件是同时具有较低的碱硅比和较低的水碱比.硅铝比等于14时,晶化温度从130℃升高到170℃,L沸石晶化区向低水碱比方向缩小,同时向较高碱硅比方向略有扩大;硅铝比和钾碱比降低均使L沸石晶化区向低碱硅比和低水碱比方向缩小.更多还原

【Abstract】 L type zeolite is synthesized with hydrothermal technique. The precipitated silicon dioxide and aluminium hydroxide are used as a source of silica and alumina, respectively. Potassium hydroxide and sodium hydroxide are used for alkali metal cations. The crystallization field of L zeolite and its changes with the synthesis conditions are studied. It is found that without L zeolite directing agent no pure L zeolite can be obtained at 150℃ and n(SiO2)/n(Al2O3)=14, the products are amorphism or W zeolite. Using directing agent, L zeolite can be obtained easily in high purity at lower n(SiO2)/n(Al2O3) ratio. The preferable synthesis conditions of L zeolite are lower water/alkali ratio and lower alkali/silica ratio. Increasing temperature from 130℃ to 170℃,the crystallization field of L zeolite at n(SiO2)/n(Al2O3)=14 will shrink to lower water/alkali ratio and expand to higher alkali/silicon ratio. Decreasing either n(SiO2)/n(Al2O3) or potassium/alkali ratio shrinks the crystallization field.更多还原