Characteristics of SBA-15 synthesized by one-step method.

The synthesis of SBA-15 with or without ethanol using a one-step method and its porosity were investigated. Well-ordered SBA-15 with a rod like morphology could be obtained from starting mixtures by aging at a low (60 degrees C) or high (80 degrees C) temperature in the presence of an appropriate amount of ethanol. By contrast, mesoporous materials containing aggregates of particles obtained in the absence of ethanol at high aging temperatures (70 or 80 degrees C) had complex poorly ordered structures, indicating that ethanol can affect the structure of mesoporous materials.

Evaluation of thermoporometry for characterization of mesoporous materials.

The accuracy of thermoporometry (TPM) in terms of the characterization of SBA-15 is examined based on a model that classifies the water in the mesopores into two different types: freezable pore water, which can form cylindrical ice crystals, and nonfreezable pore water, which cannot undergo a phase transition during a differential scanning calorimetry (DSC) measurement. Applying the empirical relationship between the sizes of the ice crystals formed in the mesopores and the solidification temperature of the freezable pore water to a thermogram (a recording of the heat flux during the solidification of the freezable pore water) yielded a size distribution of the ice crystals. The size of the ice crystals increased slightly with repetitive freezing, indicating that the mesopores were enlarged by formation of the ice crystals.