Structural Studies of Bulk to Nanosize Niobium Oxides with Correlation to Their Acidity

Hannah T. Kreissl, Molly M.J. Li, Yung Kang Peng, Keizo Nakagawa, Thomas J.N. Hooper, John V. Hanna, Ashley Shepherd, Tai Sing Wu, Yun Liang Soo, S. C.Edman Tsang

Research output: Journal article publicationJournal articleAcademic researchpeer-review

67 Citations (Scopus)

Abstract

Hydrated niobium oxides are used as strong solid acids with a wide variety of catalytic applications, yet the correlations between structure and acidity remain unclear. New insights into the structural features giving rise to Lewis and Brønsted acid sites are presently achieved. It appears that Lewis acid sites can arise from lower coordinate NbO5 and in some cases NbO4 sites, which are due to the formation of oxygen vacancies in thin and flexible NbO6 systems. Such structural flexibility of Nb-O systems is particularly pronounced in high surface area nanostructured materials, including few-layer to monolayer or mesoporous Nb2O5·nH2O synthesized in the presence of stabilizers. Bulk materials on the other hand only possess a few acid sites due to lower surface areas and structural rigidity: small numbers of Brønsted acid sites on HNb3O8 arise from a protonic structure due to the water content, whereas no acid sites are detected for anhydrous crystalline H-Nb2O5.

Original languageEnglish
Pages (from-to)12670-12680
Number of pages11
JournalJournal of the American Chemical Society
Volume139
Issue number36
DOIs
Publication statusPublished - 13 Sep 2017
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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