Critical appraisal of classical methods for determination of mesopore size distributions of MCM-41 materials

Classical methods for evaluation of the pore size distributions (PSD) from low temperature (77 K) nitrogen adsorption isotherms were compared by using a series of hexagonally ordered mesoporous silicas (MCM-41) of different pore sizes. This comparison involved the methods proposed by Barrett, Joyner and Halenda (BJH), Dollimore and Heal (DH) as well as Broekhoff and de Boer (BdB) simplified recently by Lukens et al. These methods were examined by using the statistical film thickness (t-curve) reported by Halsey (H), and Kruk, Jaroniec and Sayari (KJS). A detailed comparison of aforementioned methods shows that the BJH method with Kelvin-type equation and t-curve determined on the basis of MCM-41 materials as suggested by KJS provides the most reliable PSD. In contrast to other methods, the BJH–KJS method gives an accurate estimate of the pore width and reproduces the pore volume.