(b复旦大学化学系上海市分子催化与功能材料重点实验室 上海 200433)
以天然CXN沸石为基底材料, 通过离子交换、焙烧和酸处理等方法研究了影响该沸石水热稳定性的因素. XRD, XRF和27Al MAS NMR等结果表明阳离子种类和位置均会影响沸石水热稳定性, 其中铵型CXN沸石的水热稳定性最高. 高温焙烧铵型CXN沸石虽能提高骨架硅铝比, 但骨架缺陷增多导致其水热稳定性下降. 还研究了水蒸汽量、处理温度和时间对沸石骨架结构变化的影响, 结果表明提高温度和水蒸汽量均会降低沸石结晶度, 但处理时间则对结晶度的影响较小.
Shanghai University, Shanghai 201800)
(b Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry,
Fudan University, Shanghai 200433)
Some factors, such as calcination, ion-exchange, acid leaching etc., were studied on influencing the hydrothermal stability of natural CXN zeolite. Characterization with XRD, XRF and 27Al MAS NMR proves that the type and location of cations obviously influence the hydrothermal stability of the zeolite, and NH4-type CXN zeolite possesses the best stability. Although the framework SiO2/Al2O3 ratio of calcined NH4-CXN zeolite was enhanced, but the increase of followed framework defects greatly reduced the hydrothermal stability. The effects of steam volume, treatment temperature and time on the evolution rules of zeolite framework were also studied in this paper. The results indicate that raising the treatment temperature and steam volume decrease the zeolite crystallinity, while the effect of treatment time is negligible.