水对锂交换低硅铝比八面沸石吸附性能的影响

摘要

This paper shows quantitatively the consequence of adsorbed water on N2 or O2 adsorbed on LiLSX lithium exchanged low silica X zeolite. In the range of 0～ 32 H2O/u.c.(unit cell), water present in LiLSX sharply declined the capacity for N2 or O2 adsorption. The reason is that the adsorption mainly occurs on the Li+ ions on the 32 SIII sites in LiLSX. When H2O molecules residual after the desorption of hydrated LiLSX are adsorbed tightly on Li+ at SIII site, they block the adsorption of nitrogen or oxygen. Water molecules introduced from outside into the dehydrated LiLSX influenc the adsorption of nitrogen less seriously than the residual water molecules do, because of the heterogeneity of adsorption sites and the diffusion behavior of water in LiLSX. When diffused into the inner part of a LiLSX particle, some water molecules may adsorb on weaker sites other than the strongest SIII sites.%研究了变压吸附空气分离制氧吸附剂--锂交换低硅铝比八面沸石LiLSX中残留水及从外部引入的水对吸附性能的影响.研究表明,在水合LiLSX经脱附后,当残留的水分子数目为0～32(个分子/晶胞)时,N2或O2的吸附量下降显著.原因是N2和O2的吸附主要依赖于处在SIII位置的32个锂离子.当水分子与SIII位置的Li+结合时,就会阻碍N2或O2的吸附.而从外部引入的水分子与脱附残留的水分子相比,在相同水含量时对吸附量的影响较小,这是由于吸附位置的不均匀性以及水分子在沸石中的扩散行为所引起.在水扩散进入LiLSX内部的过程中,一部分水分子可以吸附在能量较低的位置上而不是吸附到最强的SIII位置上.