Catalytic behavior of NaV6O15 bronze for partial oxidation of hydrogen sulfide

Abstract

ElsevierSoriano Rodríguez, MD.; Rodriguez-Castellon, E.; Garcia-Gonzalez, E.; López Nieto, JM. (2014). Catalytic behavior of NaV6O15 bronze for partial oxidation of hydrogen sulfide. Catalysis AbstractNa-containing V2O5 materials have been prepared hydrothermally from gels with Na/V ratios of 0.02 to 0.34, and calcined at 500ºC. The calcined samples have been characterized and tested as catalysts in the partial oxidation of H2S to elemental sulfur.At low Na-contents, V2O5 and NaV6O15 bronze are formed, with the NaV6O15/V2O5 ratio increasing with the Na-content. Pure NaV6O15 bronze is mainly formed from gels containing a Na/V ratio of 0.18. However, NaV6O15 and NaV3O8 bronzes are formed at from gels with Na/V ratio higher than 0.35. NaV6O15 based catalyst shows high conversion for the oxidation of H2S with a high selectivity into elemental sulfur. These catalysts are more active and stable than pure or Na-doped V2O5 catalysts. V4O9 is observed in used catalysts derived from pure and Na-doped V2O5 and materials containing NaV6O15/V2O5 mixtures. However, no changes in the NaV6O15 crystalline structure are observed in pure and NaV6O15/V2O5 mixtures catalysts. Accordingly, NaV6O15 crystalline phase is stable for several hours of catalysis at a difference with V2O5. The active sites in V-containing vanadium catalysts are probably V 5+ -O-V 4+ pairs as proposed for V4O9 crystalline phase. The best catalytic performances were achieved on V2O5-NaV6O15 mixtures which are transformed to V4O9-NaV6O15 mixtures during the catalytic tests. These catalytic results could be due to the intrinsic physical properties of both phases but also because of the optimal dispersion.Keywords: NaV 6 O 15 bronze, V 2 O 5 , V 4 O 9 , selective oxidation of hydrogen sulfide to sulfur, Na-doped vanadium oxide catalyst 3

Enhancement of Electrochemical Properties of SIBs by Generating a New Phase in Potassium-Doped NaV6O15 Film Electrodes

“…The band near 1004 cm −1 is assigned to the VO stretching vibrations. 21,38,39 Several bands near the 991−937 cm −1 region can be attributed to V−O stretching vibrations, 40 while the band near 750 cm −1 is ascribed to the stretching vibrations of the V−O−V bond. 41 The band at 1606 cm −1 is the bending pattern of O−H vibrations, 36 and this band only appears in the deposited film and NK-300, representing the films still with crystalline water.…”

H2S-Selective Catalytic Oxidation: Catalysts and Processes

“…Catalysts containing vanadium oxide are active for the reaction with both a stoichiometric and an excess amount of oxygen. Moreover, binary and ternary oxides are applied widely to modify vanadium-containing catalysts, among which molybdenum-, magnesium-, iron-, bismuth-, chromium-, titanium-, manganese-, zirconium-, and alkali metal , -modified catalysts have been researched intensively. A Fe-, Bi-, Cr-, Ti-, Mn-, and Zr-modified catalyst test was performed under conditions of H 2 S/O 2 = 5/2.5, GHSV = 94 000 h –1 at different temperatures in the presence of 30% water.…”

“…In the case of alkali metal (K, Na, Li, Cs)-modified catalysts, 67,68 Na was considered as the most efficient promoter to improve the catalytic activity. The existing form of vanadium species depended mainly on the Na/V ratio.…”

Vanadium Supported on Alumina and/or Zirconia Catalysts for the Selective Transformation of Ethane and Methanol

“…Figure 2 presents the Raman spectra of supported vanadium oxide catalysts. In the case of Al 2 O 3 -supported catalysts (Figure 2a), all spectra show the presence of characteristics bands related to V 2 O 5 , i.e., 994, 702, 697, 527, 404, 284, and 146 cm −1 [50,51]. However, a broad band is also observed at ca.…”

“…The first reduction peak can be tentatively assigned to isolated or polymeric V-species [15,56], in which the reducibility of V-species in ZrO 2 -supported catalysts are higher than those in Al 2 O 3 -supported catalysts [56]. The second peak can be related to V 2 O 5 crystallites on the surface of the support (mainly observed in catalysts with high V-loading), although probably with relatively low crystal size [51], and/or attributed to the formation of small ZrV 2 O 7 crystals [27]. In this way, the reduction of pure V 2 O 5 appears at temperatures higher than 600 • C ( Figure S1).…”