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

Autor(es)

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

• Tipo de documento: Artigo Científico
• Fonte: European Journal of Inorganic Chemistry; v. 2022, n. 24, p. 10-pg., 2022-07-04.

Resumo

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)

• Processo FAPESP: 18/25649-3 - Nucleação e crescimento de zeólitas com estrutura MFI sobre superfícies de nanopartículas de Fe3O4 para a preparação de nanocatalisadores separáveis magneticamente
• Beneficiário: Diógenes Honorato Piva
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 14/50249-8 - Green chemistry: sustainable synthetic methods employing benign solvents, safer reagents, and bio-renewable feedstock
• Beneficiário: Arlene Gonçalves Corrêa
• Modalidade de apoio: Auxílio à Pesquisa - Programa Centros de Pesquisa em Engenharia