Insights into the Phosphate Species on Niobia Treated with H.sub.3PO.sub.4

Solid acid catalysts are largely used in several industrial processes, and the development of materials with high activity, selectivity and reusability is a subject of study of research groups around the world. The improvement of oxide acidity could be performed by phosphation with phosphoric acid b...

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Published inCatalysis letters Vol. 150; no. 5; pp. 1496 - 1504
Main Authors Rocha, Angela S, Costa, Gustavo C, de Araujo, Lúcia R. Raddi, Misael, Wilken A, Oliveira, Ricardo R, Rocha, Alexandre B
Format Journal Article
LanguageEnglish
Published Springer 01.05.2020
Subjects
Acetic acid
Adsorption
Catalysts
Organic acids
Phosphates
Phosphoric acid
Pyridine
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Summary:Solid acid catalysts are largely used in several industrial processes, and the development of materials with high activity, selectivity and reusability is a subject of study of research groups around the world. The improvement of oxide acidity could be performed by phosphation with phosphoric acid but the investigation of phosphated niobia is still incipient. In this work, niobia was treated with phosphoric acid solutions to generate catalysts with higher esterification activity at mild condition. The phosphated catalysts were obtained and characterized by XRD, N.sub.2 adsorption, NH.sub.3 and pyridine chemisorption and FTIR, and were tested in the esterification of acetic acid with ethanol at 60 °C and RT. DFPT calculations indicated that H.sub.2PO.sub.4 group was the predominant phosphate species on the hydroxylated surface. Theoretical results also show that ethanol adsorbs preferentially at H.sub.2PO.sub.4 acidic sites on the phosphated catalyst as compared to acetic acid.
ISSN:1011-372X
DOI:10.1007/s10562-019-03056-3