Análise da adsorção de piridina em aluminosilicatos mediante espectroscopia IV in situ e cálculos teóricos

GLAUCIO J. GOMES; JANINE C. PADILHA; MARÍA F. ZALAZAR; MARTA V. BOSCO; SEBASTIÁN E. COLLINS; PEDRO A. ARROYO

Bento Gonçalves

Congreso; 22° Congresso Brasileiro de Catálise; 2023

Sociedade Brasileira de Catálise

The application of acidic zeolites as catalysts plays a significant role in the chemical industry, due to their robustness in reactions involving a wide range of molecules and unit operations. However, the characterization and quantification of the acid sites of these catalysts have become a matter of debate in organic synthesis. In this work, the acidic sites were characterized by in situ infrared spectroscopy and the adsorption complexes (H-zeolite-probe molecule) were analyzed at fundamental level using density functional theory. The pyridine adsorption at low temperatures can overestimate the presence of Lewis acid sites. Bands referring to pyridine physiosorption were observed up to 190 ℃ in the region of 1453 and 1444 cm-1. At high temperatures, the confinement effect was observed for the zeolites H-ZSM-5 and H-Beta, and this information is justified by calculations of electronic structures that show that the confinement caused by the morphology of the pores and cavities implies a conformation that favors the optimization of H bonds in confined void environments.