磷改性对Y型分子筛结构及催化性能的影响

Influence of Phosphate Modification on the Structure and Catalytic Performance of Zeolite Y

摘要:

采用原位晶化法制备含磷的PY分子筛，利用X射线衍射（XRD）、程序升温氨脱附（NH3-TPD）等测试方法对磷改性的PY型分子筛进行表征。结果表明，磷的引入不影响分子筛的晶型，其分子筛的相对结晶度变化很小，晶胞收缩，晶胞常数减小；分子筛的硅/铝摩尔比增大。磷改性可以有效调变催化剂的酸量和酸强度，磷的引入降低催化剂的总酸量、弱酸量和强酸量，增加催化剂的中强酸的酸量。在小型固定流化床装置上对改性后的催化剂进行性能评价，发现改性后的催化剂具有很强的的重质油转化能力和良好的裂化产物选择性。

Abstract:

The zeolite Y synthesized by in-situ crystallization technique was modified with phosphate. The crystalline structure and surface acidity of the modified zeolite Y(named zeolite PY) were characterized by using techniques such as X-ray diffraction ( XRD) , NH3 temperature programming desorption (NH3-TPD). The results showed that the introduction of phosphorus had no effect on crystal form of the zeolite PY, and the caused impact on relative crystallinity was obscure. Moreover, the space unit shrank, the cell parameter decreased, and the molar ratio of Si/Al increased. It was found that the modified PY catalyst could effectively adjust the total acid amount and acid strength of the catalysts. The introduction of phosphorus could also decrease the total acidity, weak acidity and strong acidity, but increased the moderately strong acidity. Further evaluation that carried on a small fixed fluidized bed showed that the modified PY catalyst exhibited excellent heavy oil cracking capability an d superior selectivity to desired products．