Investigating trimethylphosphine oxide interactions with Brønsted and Lewis acid sites in zeolites: a comparative solid-state NMR study of wet-phase and gas-phase adsorption techniques

• Autor(a) principal: Bornes, Carlos
• Data de Publicação: 2023
• Outros Autores: Geraldes, Carlos F.G.C., Rocha, João, Mafra, Luís
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/38046
• topic: Zeolite; Brønsted acid; Probe molecule; Adsorption; Host-guest interaction

This study examines the differences in using two primary methods for adsorbing TMPO onto acid catalysts and their influence on the NMR spectra of TMPO-loaded zeolites. The findings show that TMPO molecules interact with both Brønsted and Lewis acid sites, and that the amount of (TMPO)2H+ dimers formed increases with the amount of TMPO added. The use of dichloromethane as a solvent inhibits the formation of dimers and crystalline TMPO but may lead to inaccurate estimations of acid site strength and quantification due to interactions with residual solvent molecules. The gas-phase method is preferred for adsorbing TMPO onto zeolites, but caution is needed to avoid forming a high number of dimers that make interpretation of the NMR spectra challenging.