Effect of various pillaring oxides on adsorption behaviour of novel MCM-36 derivatives

Abstract

For MCM-36 derivatives pillared with various mixed oxides, adsorption isotherms of nitrogen, argon, benzene, ethanol, and water have been measured and discussed. The dimensions, specific surface area, and volume of the mesopores depend on the reagents used for intercalation. Pure SiO 2 pillars mechanically support the expanded layers while other metal oxides also create new adsorption centres in the materials. Two factors influence the adsorption properties in a synergy: the mesopore dimensions and interactions between specific adsorption sites and adsorbates. All the isotherms and pore size distributions show a clear division of the materials into two groups without and with silica in the pillars. The former group shows a higher stability. The latter one exhibits distinctly higher sorption capacities at smaller mesopore sizes and broader distributions of sizes due to more complex pillaring species. The measurements revealed a tendency for an increase in sorption capacities (with some exceptions and excluding ethanol): no pillars (MCM-22) < single < two < three metal oxide composite pillars, although the reasons for this effect remain unclear.