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

采用原位晶化法制备含磷的PY型分子筛,并用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型分子筛进行了表征。结果表明,磷的引入不影响分子筛的晶形,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(简称硅铝比,下同)增大。适量磷(质量分数0.1%)的引入降低了催化剂的总酸量、弱酸量和强酸量,增加了催化剂的中强酸的酸量。因此,可以有效调变催化剂的酸量和酸强度。在小型固定流化床装置上对催化剂的反应性能进行评价,发现与Y型催化剂相比,PY型催化剂在总液收提高了2.35%的条件下,使重油产率降低了0.32%,焦炭产率降低了0.22%,同时汽油收率和轻油收率分别提高了1.75%和1.68%,表现出很强的重质油转化能力和良好的裂化产物选择性。

Zeolite Y was successfully synthesized by employing in-situ crystallization method and further modification with the introduction of phosphate. The properties of the obtained zeolite PY were characterized by means of such techniques as X-ray diffraction （XRD） , NH3 temperature programming desorption（NH3-TPD） ,etc. It has been demonstrated that the introduction of,phosphorus had no effect on the crystal form of zeolite PY, and its impact on relative crystallinity was obscure. Moreover, the space unit shrank and the cell parameter decreased, and the molar ratio of Si/A1 increased. It was found that the modified PY catalyst could effectively adjust the acidic amount and strength of the catalysts. Specifically, the introduction of a proper quantity （0. 1% ） of phosphate could decrease the total acidic amount, weak acidic amount and strong acidic amount ,whereas the moderate acidic amount increased. Further evaluation carried out on a small fixed fluidized bed shows that the modified PY catalyst increased the overall liquid yield by 2.35% ,while it decreased the heavy oil yield and coke yield by 0. 32% and 0. 22% ,respectively;meanwhile,the yields of gasoline and light oil increased by 1.75% and 1.68% respectively. These results demonstrate that the modified PY catalyst exhibits excellent heavy oil cracking capability and superior selectivity.