【摘要】 <正> 沸石分子筛具有规整的晶体结构,在微孔中存在着强大的吸附力场,研究分子筛在低压下的吸附性能有着重要的理论和实际意义.研究A,X,E型等低硅铝比分子筛在低压下对空气、N₂、O₂和Ar等的吸附性能以及吸附理论的适用性已有报道.但对ZSM-5分子筛的低压吸附规律的研究,尚未见文献报道.本文研究了ZSM-5系列分子筛更多还原

【Abstract】 The adsorption isotherms of air, N2, O2 and argon on a series of ZSM-5 zeolites at low temperature (77K) and pressure (10-7-10-4torr) were measured by volumetric method. The results show that cation types, silica-alumina ratio, calcination temperature and pretreatment of ZSM-5 zeolites all have effects on the adsorption properties. The contributions of the dispersive force and the electrostatic force to the amounts of adsorption on ZSM-5 zeolites were discussed. Some primary information about the improvement of adsorption properties of zeolites at low pressure was obtained.A discussion of the applicability of several theories to the adsorption on zeolites at low pressure and temperature demonstrates that for ZSM-5 with high ratio of silica-alumina (greater than 38) the theory of volume filling of micropore (TVFM) is satisfiable. However, for NaX, CaA,NaM and ZSM-5 zeolites with low ratio of silica-alumina the applicability of TVFM is limited, it is possible that they contain more cations so that they bring about more component of electrostatic interaction, especially at low degree of filling, which is so large that the basic assumption of TVFM is not applicable. In addition, Henry’s law and Freundlich equation are not applicable in the whole pressure range (5× 10-8-5×10-4torr), except the Freundlich equation in smaller pressure range.The zigzag phenomena or the vertical jump of adsorption isoth-erms of N2,O2,Ar and air on ZSM-5 zeolites were observed. It is possible that the phase transformation of adsorbate occurs on ZSM-5 zeolites.更多还原