Efficient Dry Impregnation of Zirconium into H-ZSM-5 Zeolites

Author(s)

de Macedo, Vinicius ; de Lima, Rafael O. P. ; Piva, Diogenes H.

• Document type: Journal article
• Source: European Journal of Inorganic Chemistry; v. 2022, n. 24, p. 10-pg., 2022-07-04.

Abstract

There is considerable interest in adjusting the acidity and pore architecture of zeolites. Herein, we present solventless incorporation of zirconium (similar to 2-10 wt.%) in a precursor and desilicated (0.2 and 0.4 mol L-1 NaOH) H-ZSM-5 zeolite. Infrared and UV-visDR spectroscopy confirmed the grafting of highly dispersed Zr in all the zeolites. XRD indicated the presence of ZrO2 in zeolites with higher Zr contents. The micropore volume of the precursor zeolite decreased by similar to 10%, suggesting the presence of Zr mainly on the external surface, while it decreased more than 20% for the desilicated sample, suggesting Zr had access to the micropores at higher Zr contents. Infrared spectroscopy after pyridine adsorption provided evidence for the Bronsted and Lewis acid sites in all zeolites, but the Bronsted acid-to-Lewis acid site ratio decreased by >50% depending on the Zr and NaOH concentrations. The presence of Zr critically changed the predominant nature of the acid sites of the desilicated zeolites. (AU)

• FAPESP's process: 18/25649-3 - Nucleation and growth of zeolite MFI-Type structure on the surface of Fe3O4 nanoparticles for the preparation of magnetically separable nanocatalysts
• Grantee: Diógenes Honorato Piva
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 14/50249-8 - Green chemistry: sustainable synthetic methods employing benign solvents, safer reagents, and bio-renewable feedstock
• Grantee: Arlene Gonçalves Corrêa
• Support Opportunities: Research Grants - Research Centers in Engineering Program