ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Selective methane oxidation to formaldehyde using polymorphic T-, M-, and H-forms of niobium(V) oxide as catalysts

Beata Michalkiewicz, Joanna Sreńscek-Nazzal, Piotr Tabero, Barbara Grzmil, and Urszula Narkiewicz

Institute of Chemical and Environment Engineering, Szczecin University of Technology, PL 70-322 Szczecin, Poland

E-mail: beata.michalkiewicz@ps.pl

Received: 24 March 2007  Revised: 13 July 2007  Accepted: 17 July 2007

Abstract: The investigations of selective methane oxidation to formaldehyde over T-Nb₂O₅, the mixture of M-Nb₂O₅ and H-Nb₂O₅ as well as H-Nb₂O₅ were carried out. The tests were conducted under atmospheric pressure, in the temperature range 420–750°C, using oxygen as the oxidizing agent. T-Nb₂O₅ samples were examined at the contact time 0.7–1.8 s (GHSV 2000–5143 h⁻¹). Other polymorphic forms of niobium(V) oxide were examined at the contact time 0.9 s. Various polymorphic forms of Nb₂O₅ displayed various formaldehyde and carbon dioxide yield. Using H-Nb₂O₅ and M-Nb₂O₅ phases with a block type structure, made it possible to obtain higher formaldehyde selectivity (78 % at 0.9 s) as compared to T-Nb₂O₅ (47 % at 0.9 s), a polymorphic form which does not have a block type structure. However, the highest space time yield of formaldehyde (46 g per kg of catalyst per h) was obtained over T-Nb₂O₅ supported on SiO₂.

Keywords: methane - formaldehyde - niobium(V) oxide - selective methane oxidation

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-007-0086-4

Chemical Papers 62 (1) 106–113 (2008)