改性Hβ沸石的物化性能表征

Study on Physical Chemistry Properties of Modified Naβ Zeolite

用相同物质的量浓度的硝酸铵、柠檬酸以及柠檬酸铵溶液对Naβ沸石进行改性处理得到Hβ沸石;采用XRD、XRF、FT-IR、27Al MAS NMR和29Si MAS NMR等表征手段进行分析。结果表明,采用含羟基的柠檬酸或柠檬酸铵对Naβ沸石进行改性处理,不但可以提高样品结晶度还可以有效限制骨架铝的脱除;经柠檬酸或柠檬酸铵改性可以使Naβ中的Al(S4R,SiteA)转化成Al(S6R,SiteB),而硝酸铵改性的Naβ沸石中只发现一种骨架四面体;还发现硝酸铵和柠檬酸铵改性Naβ沸石后,少量的骨架铝转化为非骨架铝并存在于孔道内,而经过柠檬酸改性后,这部分非骨架铝被带出孔道。

Naβ zeolite is modified by ammonium nitrate,citric acid and ammonium citrate solution to obtain Hβ zeolite, and the product is characterized by the XRD, XRF, FT- IR,^27Al MAS NMR and ^29Si MAS NMR. The results show that the modified treatment of Naβ zeolite with the hydroxyl group containing citric acid and ammonium citrate, not only have a higher relative crystallinity, but also can restrict the removal of framework tetrahedral AI, the AI（ S4R, SiteA）can be easily convert to Al （S6R, SiteB ）, while only one type of framework tetrahedral Al is found in Naβ modified by ammonium nitrate. Ammonium nitrate, citric acid and ammonium citrate solution all can turn the part of framework Al into non framework Al, and the non framework Al may exist in the cavity in Naβ modified by ammonium nitrate or ammonium citrate. However,the non framework Al in Naβ modified by citric acid can be carried out the cavity.