Mechanical and hydrothermal stability of mesoporous materials at extreme conditions

• Nanoscale architecture affects stability of mesoporous silica under high pressure.
• Hydrolysis is not the cause of collapse of pore structure at high pressure.
• SBA-15 type mesoporous carbon is highly hydrothermally stable.
• FDU-12 silica is irreversibly disordered in extreme hydrothermal conditions.

In situ SAXS measurements were made on periodic mesoporous carbon and silica-based materials as a function of pressure and temperature and in water to supercritical conditions. Our data show that periodic mesoporous silica-based materials exhibit substantial mechanical strength. The pore structure, size and related mesoscale properties appear to directly impact the mechanical response of silica-based materials to high pressures and temperatures. Our results indicate that hydrolysis does not seem to be responsible for the mechanical collapse of the pore structure of silica-based mesoporous materials under high pressure conditions. SBA-15 type mesoporous carbon exhibits excellent hydrothermal stability under extreme conditions. The mesostructure of FDU-12 silica is irreversibly disordered after extreme hydrothermal exposure in a manner consistent with H2O dissociation reactions causing topological alteration of the silicate network.

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