Mechanism of complete n-hexane oxidation on silica supported cobalt and manganese catalysts | Health & Environmental Research Online (HERO)

Health & Environmental Research Online (HERO)

Print Feedback Export to File

This record has one attached file:

Citation
Tags

HERO ID

1570264

Reference Type

Journal Article

Title

Mechanism of complete n-hexane oxidation on silica supported cobalt and manganese catalysts

Author(s)

Todorova, S; Naydenov, A; Kolev, H; Holgado, JP; Ivanov, G; Kadinov, G; Caballero, A

Year

2012

Is Peer Reviewed?

Journal

Applied Catalysis A: General
ISSN: 0926-860X
EISSN: 1873-3875

Publisher

ELSEVIER

Location

AMSTERDAM

Volume

413

Page Numbers

43-51

Language

English

DOI

10.1016/j.apcata.2011.10.041

Web of Science Id

WOS:000299981500006

Abstract

Mono- and bi-component cobalt and manganese samples were prepared by impregnation of silica with aqueous solutions of Co(NO3)(2)center dot 6H(2)O and/or Mn(NO3)(2)center dot 6H(2)O. The bi-component samples were obtained by a common solution of Co- and Mn nitrates (CoMn-MS) or by deposition of cobalt on calcined Mn sample (Co + Mn). The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), temperature programmed reduction (TPR). Fourier transformed infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), elemental analysis and tested in reaction of complete n-hexane oxidation. It was observed that the well crystalline cobalt oxide partially covers poorly crystalline manganese oxide in the Co + Mn catalysts, while finely divided oxides (MnO2 and Mn2O3, Co3O4) are present on the surface of the (CoMn-MS) sample. Four Langmuir-Hinshelwood and two Mars-van Krevelen models were fitted with the experimental data from the catalytic tests. According to the model calculations and results from instrumental methods, the reaction pathway over single component manganese and bi-component Co-Mn catalysts proceeds through Mars-van Krevelen mechanism (the oxidation of the catalyst surface being the rate determining step), while Langmuir-Hinshelwood mechanism is more probable for the Co sample. A considerable increase in activity for the sample obtained from a mixed solution is explained by low crystallinity, simultaneous presence of Mn4+-Mn3+ and enrichment of the surface in oxygen species. (C) 2011 Elsevier B.V. All rights reserved.

Keywords

n-Hexane complete oxidation; Kinetics models; Supported Co-Mn oxide catalysts