Characterization of natural phillipsite modified with orthophosphoric acid

Natural phillipsite from Tenerife (Canary Islands) has been treated with orthophosphoric acid at several concentrations. Structural modifications arising from the treatment were studied by several techniques, including XRD, FTIR, XPS, SEM and porosimetry. Phillipsite undergoes partial dealumination as a consequence of the treatment. Aluminium accumulates on the zeolite surface as aluminium phosphate, but also inside the zeolite pores, as shown by XPS analysis. Both the surface area and the pore volume of the material increase with increasing concentrations of ortophosphoric acid, and this behavior is more marked at the microporosity level (below 20 إ). A careful examination of XRD data evidences that the zeolite crystals have been split along the a-axis as a result of the treatment. These assumptions were confirmed by SEM.