Determination of Microporous and Mesoporous Surface Areas and Volumes of Mesoporous Zeolites by Corrected t-Plot Analysis

Zeolites are well-known microporous catalysts involved in many industrial applications. Their microporosity yet impedes diffusion of bulky molecules. To overcome this drawback, zeolites with hierarchical bimodal porosity, e. g. micropores and mesopores, are developed. In this context, it is important to develop/use methods able to evaluate accurately the textural properties of mesoporous zeolites. t-Plot can be in theory used for determining the micro- and mesopore surface areas and pore volumes. However, classical t-plot analysis overestimates the mesopore surface areas and underestimates the micropore volumes for hierarchical micro-/mesoporous materials. Measurements performed with mechanical mixtures of FAU-Y and MCM-41 allows to provide corrections, which are up to date limited to mesoporous FAU-Y. The present work describes specific corrections of the t-plot for a broader series of zeolites including MFI, *BEA and MOR, based on a set of mechanical mixtures of zeolites and MCM-41. Minor correction factors are required for MOR, whilst for MFI and *BEA similar corrections as for the FAU-Y are inferred for the micropore volume. As far as the surface area is concerned higher correction factors are required for MFI compared to *BEA. This corrected t-plot analysis is applied to characterize a great variety of mesoporous zeolites prepared by micelle-templating.