AEI结构杂原子磷铝分子筛的合成、表征及MTO催化性能

SYNTHESIS,CHARACTERIZATION AND CATALYTIC PROPERTIES OF HETEROATOMS SUBSTITUTED ALUMINOPHOSPHATE SIEVES WITH AEI FRAMEWORK TOPOLOGY

采用水热法合成了杂原子Co、Mn、Mg、Si取代的AlPO4-18(AEI结构)分子筛。采用XRD、NH3-TPD、DTA方法对其进行表征,并以甲醇制烯烃(MTO)反应评价其催化活性。结果表明,杂原子Co、Mn、Mg、Si取代的AlPO4-18分子筛热稳定性较AlPO4-18稍差,但骨架破坏温度仍在1380 K以上。AlPO4-18分子筛的酸性会随着杂原子的取代而增强,其中Si的取代使分子筛酸性增强最多。在1033 K、100%水蒸气处理下,杂原子磷铝分子筛具有较好的水热稳定性,但随着水热处理时间延长,结晶度缓慢降低,骨架破坏并转变为无定形。CoAPO-18、MnAPO-18、MgAPO-18和SAPO-18分子筛都具有一定的MTO催化性能,其中CoAPO-18催化性能最好,甲醇转化率、丙烯收率和乙烯收率分别达到100%、49.79%、24.5%。

Heteroatoms （Co, Mn, Mg, Si） substituted aluminophosphate molecular sieves （MAPO-18） with AEI framework topology were hydrothermally synthesized and characterized by XRD, DTA and NH3-TPD. The hydrothermal stability of MAPO-18 （Co, Mn, Mg, Si） wasinvestigated with XRD under hydrothermal conditions （1033 K, 100% vapor）. The results showed that MAPO-18（M=Co, Mn, Mg, Si） possessed the thermal stability some what lower than that of APO4-18, but their framework collapse temperatures were still above 1380 K. The incorporation of heteroatoms（Co, Mn, Mg, Si） into framework of AlPO4-18 increased its acid strength and the incorporation of Si did the most. MAPO-18（Co, Mn, Mg, Si） possessed good hydrothermal stability, but with the treated time extending, their framework collapsed and transformed into amorphous. As the catalyst for MTO, MAPO-18（Co, Mn, Mg, Si） have good catalytic performance, among which CoAPO-18 was the best one and the methanol conversion, ethylene selectivity and propylene selectivity of MTO were 100%, 49.79%, 24.5 %, respectively.