用于MTP反应ZSM-5分子筛的磷改性研究

将P改性用于甲醇制丙烯(MTP)反应ZSM-5分子筛的改性研究,以提高丙烯选择性和分子筛活性稳定性。采用XRD、SEM和NH_3-TPD表征催化剂物化性能。对不同硅铝比ZSM-5分子筛P改性研究发现,3种不同硅铝物质的量比(50、150和300)ZSM-5分子筛进行P改性时,在n(P)∶n(Al)=0.5~0.7时,ZSM-5分子筛改性后丙烯选择性和寿命得到提升。研究分子筛晶粒尺寸与P负载量关系时发现,随着分子筛晶粒尺寸的增大,位于分子筛表面的P含量逐渐增加,并且分子筛晶粒越小,最佳的P负载量越小。

Research on P modification of ZSM-5 zeolites for MTP reaction

In order to improve the selectivity to propylene and zeolite stability,ZSM-5 zeolites for methanol to propylene were modified by phosphorus.The physicochemical properties of the resulting samples were characterized by XRD,SEM and NH3-TPD.Screening and optimizing modification conditions were carried out to clarify the relationships between the properties of zeolites and the modification conditions.The results showed that after ZSM-5 zeolites with SiO2/Al2O3 molar ratios of 50,150 and 300 were modified by using P and controlling P/Al molar ratio of 0.5-0.7 in ZSM-5 zeolites,the selectivity to propylene and zeolite stability were enhanced.With the enhancement of crystal size of ZSM-5 zeolites,the content of P on the surface of the zeolites increased gradually;the smaller the crystal size of ZSM-5 zeolite is,the lower the optimal P loading is.