Thermoporosimetry of n-alkanes for characterization of mesoporous SBA-15 silicas – Refinement of methodology

• General experimental protocol for n-alkane thermoporosimetry has been established.
• Significance of n-alkane probe liquid/porous solid mass ratio has been demonstrated.
• Suitability of n-hexane, n-heptane and n-octane as TPM probes has been evaluated.
• Empirical calibration equations for n-heptane and n-octane TPM have been derived.

This report focused on setting up general experimental protocols for n-alkanes thermoporosimetry (TPM) in application for the study of porosity in a series of mesoporous SBA-15 silicas. The results were referred to the porosity characteristics obtained from nitrogen adsorption/desorption at −196 °C and quasi-equilibrated temperature programmed desorption and adsorption (QE-TPDA) of nonane. n-Hexane, n-heptane and n-octane were used as liquid probes in TPM experiments. For the first time the role of heating and cooling rate and liquid to solid mass ratio in n-alkane-TPM measurements was evaluated. n-Heptane was found to be the most appropriate n-alkane probe, n-octane admissible one, and n-hexane unsuitable due to the strong dependence of the DSC effects on choice of experimental conditions. Empirical calibration equations for n-heptane and n-octane thermoporosimetry were established.

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