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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