Characterization of Ordered Mesoporous Silicas using Adsorption of N2, Ar, O2, CH4 and H2 at 77 K

JHONNY VILLARROEL ROCHA; DEICY BARRERA; KARIM SAPAG

Delray Beach

Workshop; CPM-7: The 7th international workshop characterization of porous materials: from angstroms to millimeters; 2015

Quantachrome Instruments and Rutger University

The experimental technique commonly used for textural characterization of ordered mesoporous silicas (OMS) such as MCM-41, MCM-48, SBA-15 and SBA-16 is the gas adsorption [1], in particular N2 adsorption ? desorption at 77 K. This technique is considered as the standard experimental technique to evaluate the textural properties of porous materials [2, 3]. However, several authors [4-7] consider that the permanent quadrupole moment of N2 molecule has specific interactions with the silanol surface groups on silica materials, thereby causing an effect of preferred orientation of the N2 molecule adsorbed [5]. In this sense, several authors have characterized some of these OMS by Ar adsorption (at 77 and 87 K), where the MCM-41 has been widely studied. However, the use as gas characterization of other adsorptives with null permanent quadrupole moment as O2, CH4 and H2 is scarcely considered.In this work, the adsorption of gases as N2, Ar, O2, CH4 and H2 at 77 K were analized on MCM-41, MCM-48, SBA-15 and SBA-16 materials, in order to obtain a more complete information about their texture and pore structure