超细NaY分子筛的深度脱铝

Deep Dealumination of Ultrafine NaY Zeolite

通过优化和组合不同脱铝补硅方法,依次经氟硅酸铵处理、600oC水热处理、硅溶胶+草酸处理和800oC水热处理过程,成功实现了200nm超细NaY分子筛的深度脱铝,最终产品骨架硅铝比高达27.3,比表面积为581.9m2/g,分子筛结晶度保持在65%以上.结果表明,对于超细NaY分子筛脱铝,第一步采用氟硅酸铵进行部分缺陷修补尤为重要.根据分子筛晶粒尺寸不同,需严格控制氟硅酸铵用量和处理次数.当晶粒为200nm时,氟硅酸铵与分子筛骨架铝的摩尔比为0.16,处理一次较为适宜.在连续脱铝过程中及时补修脱铝产生的缺陷是保障超细NaY分子筛成功脱铝的关键,而采用氟硅酸铵、硅溶胶、800oC高温水热处理,可有效实施这种骨架修正作用.

The ultrafine NaY zeolite with 200 nm grain size was dealuminated deeply by the optimized treatment of （NH4）2SiF6 solution, steamed at 600 oC, silicon sol ＋ oxalic acid, and steamed at 800 oC, respectively. The first treatment of （NH4）2SiF6 solution is very important, which can fix the framework defects of zeolite and strengthen its stability. The amount of （NH4）2SiF6 and treated number need to be carefully controlled according to the grain size of NaY zeolite. For 200 nm NaY zeolite, the best molar ratio of （NH4）2SiF6 to framework aluminum of zeolite is 0.16 and once treatment is relatively appropriate. The final dealuminated Y zeolite has the high framework Si/Al ratio of 27.3 and surface area of 581.9 m2/g, as well as the crystallinity of 65%. The key factor for the successful deep dealumination of ultrafine Y zeolite is to repair promptly its crystal defects resulting from the dealumination process. The treatments of （NH4）2SiF6 solution, silicon sol, and steamed at 800 oC appear such effect.