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Pore Size Effect on Methane Adsorption in Mesoporous Silica Materials Studied by Small-Angle Neutron Scattering

Published

Author(s)

Wei-Shan NMN Chiang, Emiliano Fratini, Piero Baglioni, Jin-hong Chen, Yun Liu

Abstract

Methane adsorption onto the model mesoporous silica materials in the size range characteristic of shale is studied by small-angle neutron scattering (SANS). Size effect on the temperature-dependent gas adsorption is investigated by SANS using MCM-41 and SBA-15 as adsorbents and methane pressure at about 100 kPa. Above the gas-liquid condensation temperature, the thickness of the adsorption properties, such as adsorbed layer thickness and the amount of adsorbed gas, have little dependence on the pore size being studied, i.e. pore radius of 16.5 A and 34.1 A, but seem to be mainly affected by the roughness of the pore surfaces. Hence, the surface properties of the pore wall are more dominant than the pore size, and shift to higher temperature when the pore size is smaller. Close to the gas-liquid condensation temperature, even though the majority of gas adsorption experiments/simulations have assumed the density of confined liquid to be the same as the bulk density, the measured methane mass density in our samples is found to be all appreciable smaller than the bulk methane density irrelevant to the pore sizes studied here. The change of the mass density of liquid/solid methane in pores with different sizes show different temperature dependence below the condensation temperature. While the density of the methane in the larger pore 9SBA-15) shows a more abrupt increase of density when the temperature is decreased below 60 K, the methane density in the smaller pore (MCM-41) shows a continuous increase as the temperature is decreased until the temperature is below about 30K.
Citation
Langmuir
Volume
32
Issue
35

Keywords

Methane, gas adsorption, pore size, mesoporous materials, MCM-41, SBA-15, Small-Angle Neutron Scattering

Citation

, W. , Fratini, E. , Baglioni, P. , Chen, J. and Liu, Y. (2016), Pore Size Effect on Methane Adsorption in Mesoporous Silica Materials Studied by Small-Angle Neutron Scattering, Langmuir, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=920974 (Accessed April 13, 2024)
Created August 11, 2016, Updated September 19, 2017