Post-synthetic thermal and chemical treatments of H-BEA zeolite: effects on the catalytic activity

Abstract

A beta zeolite sample (SiO 2/Al 2O 3=25) was dealuminated by thermal treatment in the 773–1023 K temperature range. One sample, after the treatment at 923 K, was further washed with diluted HCl solution and rinsed with water, in order to remove the extraframework aluminum debris from its surface. Structural and morphological changes were monitored by powder X-ray diffraction, nitrogen adsorption–desorption and FT-IR spectroscopy, the surface acidity was evaluated by temperature programmed desorption of ammonia, FT-IR of adsorbed pyridine and potentiometric titration. The influence of the thermal treatments on the catalytic activity of the zeolite samples was tested in the anisole acylation and the Baeyer–Villiger oxidation of cyclohexanone. The catalytic performances were correlated with the physico-chemical and structural changes induced on the catalyst by the thermal and/or chemical pretreatments.