Evaluation of Brønsted and Lewis acid sites in H-ZSM-5 and H-USY with or without metal modification using probe molecule-synchrotron X-ray powder diffraction

Abstract

The adsorbate interactions of furans as probe molecules in H-ZSM-5 and H-USY with and without metal ion modification have been revealed by synchrotron X-ray powder diffraction (SXRD). The Rietveld refinements give both qualitatively and quantitatively the spatial arrangements and adsorption geometries of furan and 2,5-dimethylfuran (DMF) on the Brønsted acid sites (BAS) and metal Lewis acid sites (LAS). The bonding information between the adsorbate-framework can also be correlated with thermogravimetric findings. The use of probe molecule-SXRD can be used as a new characterisation tool which can spatially interrogate the acidity of crystalline porous catalysts, leading to molecular engineering of new catalytic systems.