Abstract
Two families of calcined highly ordered mesoporous silicas, designed as M41S (MCM-41 and MCM-48) and SBA-n (SBA-15 and SBA-16), are investigated in a wide range of pore sizes from 2.1 to 26.4 nm by high-temperature oxide melt solution calorimetry using lead borate solvent at 974 K. These data are consistent with and extend our earlier studies of zeolite microporous and of mesoporous silicas. The formation enthalpies observed are 19.0−31.4 kJ/mol less exothermic than that of quartz and correlate linearly with pore size for a given structure type. Small- and wide-angle X-ray scattering, nitrogen adsorption (BET), thermogravimetric analysis, and 29Si NMR are employed to give insight into structure and symmetry. The enthalpy differences among samples are discussed in terms of symmetry and structural (point and ring) defects in the materials.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
