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Characterization of the surface acidity in niobium phosphates by FTIR using probe molecules

Grant number: 18/10536-9
Support type:Scholarships abroad - Research Internship - Scientific Initiation
Effective date (Start): August 01, 2018
Effective date (End): October 29, 2018
Field of knowledge:Engineering - Chemical Engineering
Principal Investigator:José Maria Correa Bueno
Grantee:José Lucas Vieira
Supervisor abroad: Chiara Bisio
Home Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
Local de pesquisa : Università degli Studi del Piemonte Orientale Amedeo Avogadro, Alessandria, Italy  
Associated to the scholarship:17/17042-9 - Catalytic study of the direct conversion of glucose to 5-hydroxymethylfurfural using niobium-based catalysts, BP.IC

Abstract

During the present scientific initiation project, we have been studying the catalytic activity of selected niobium phosphates (obtained by the student in a previous scientific initiation project) for the conversion of glucose in HMF and xylose to furfural. The results have been also compared with the CBMM commercial niobium phosphate (NbP-CBMM). As described in the first report submitted to FAPESP, we observed that the catalyst activity and selectivity is strongly affected by the preparation method. The best catalytic results were obtained for the NbP-2-SDS-Ext550, reaching similar performances to the commercial NbP-CBMM. The catalytic properties of the catalyst are strongly related to their surface acidity, hence, in order to understand and explain the results obtained, it is imperative to understand the catalyst surface properties. Therefore, herein, it is proposed the study of the acid surface properties of the niobium phosphate using adsorption of probe molecules (ammonia, pyridine, carbon monoxide, and deuterated acetonitrile) monitored by Fourier Transform Infrared Spectroscopy (FTIR). Thus, it is sought to obtain the concentration of Brønsted and Lewis acid surface sites of these samples using the probe molecules ammonia and pyridine, respectively. The thermal stability of the adsorption of these molecules with the acid sites can also provide information related to their strength. A more direct determination of the strength of the Brønsted acid sites will be carry out using CO adsorption at -173 °C and for the determination of the Lewis acid strength, deuterated acetonitrile adsorption will be used. (AU)