Characterization of ordered mesoporous carbons synthesized using MCM-48 silicas as templates

Abstract

CMK-1 ordered mesoporous carbons were synthesized using MCM-48 silica templates with a wide range of unit-cell parameters and pore sizes. Sucrose and furfuryl alcohol were employed as carbon precursors. It was confirmed that the isolation of the CMK-1 carbon via dissolution of the MCM-48 template is accompanied by a structural transformation, which manifests itself in the change of the X-ray diffraction pattern. It is suggested that the transformation is related to the disconnected nature of the two interwoven parts of the CMK-1 framework (which are formed in two enantiomeric MCM-48 channel systems separated by the silica wall) and may involve a mutual displacement of these two parts to create some contact between them and fix their mutual position. It was shown that the application of different MCM-48 templates allowed for tailoring of the CMK-1 unit-cell size. However, the primary mesopore size of CMK-1 was found to be relatively constant. This was explained as a consequence of the formation of primary mesopores of CMK-1 in the space previously occupied by the MCM-48 pore walls, and attributed to the similarity in the pore wall thickness for the MCM-48 templates used. Our study confirmed that the uniform mesopores of CMK-1 are accompanied by micropores and that the carbon prepared using MCM-41 as a template collapses upon the template removal to yield high-surface-area disordered microporous structure. It was also shown that thermogravimetric weight loss behavior under air atmosphere provides important insights to the structural integrity and quality of the CMK-1 samples.