沸石的孔口改性与气体吸附分离

沸石由干具有独特的微孔结构和表面性质，对物质的吸附表现出高度的选择性，已被广泛用于许多工业吸附分离过程．在气体分离方面，最常见的是利用沸石制造纯净的稀有气体和富氧空气．Niwa等［‘－‘］和本实验室［‘’］已成功地采用出（OCH小化学气相沉积方法对HM和Hi8M七沸石进行孔径精细调变，改善了沸石的择形吸附分离和催化性能．本文试图进一步研究沸石孔口改性在气体吸附分离方面的应用潜力．我们选择的H元气体混合物体系是NZ／OZ和CH。川。，因为O。，NZ和CH。三种分子的动力学直径分别为0．346O．364和0．380urn，相差甚…

Fine Control of Zeolite Pore-opening Size and Gas Separation

The performance of various types of zeolites for N2/O2 and CH4/N2 separation has been studied. The separation factors αN2/O2 and αCH4/N2 for all the Na-form zeolites are < 1. Compared with Na-form zeolites, H-form zeolites adsorb larger quantities of O2 and smaller quantities of N2, so αN2/O2 is increased, but αCH4/N2 is reduced. On the contrast, Ca-form zeolites adsorb larger quantities of N2, so αN2/O2 is reduced but αCH4/N2 is increased. However the αN2/O2 and αCH4/N2 for both H- and Ca- form zeolites are ＜1.The changes in adsorption behavior can be explained in the light of energetics of sorption in zeolites. Chemical vapor deposition with silicon methoxide has been used to control the pore-opening size of the zeolites. As the amount of SiO2 deposition on NaA is increased, the adsorption of the bulkier component in the binary gas mixture is suppressed, so the values of αN2/O2 and αCH4/N2 for SiNaA zeolites are increased quickly to >1. Experimental results show that if the right type of zeolite is chosen fine control of zeolites pore-opening size through chemical vapor deposition has a potential as a good method for preparing high selective adsorbent in gas separation.