Salt-induced formation of hollow and mesoporous CoOx/SiO2 spheres and their catalytic behavior in toluene oxidation

Liang-Yi Lin, Hsun-Ling Bai

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

Hollow and mesoporous CoOx/SiO2 spheres (denoted as CoOx/hSiO2 and CoOx/mSiO2) were synthesized via salt-assisted ultrasonic spray pyrolysis. Precursor solutions containing sodium silicate solution, a mineral acid (hydrochloric acid or nitric acid) and a cobalt salt were ultrasonically aerosolized and pyrolyzed. Results showed that CoOx/SiO2 spheres with hollow or mesoporous structure can be fabricated by using the NaCl and NaNO3 salts as in situ formed templates. Significantly, this approach avoids the need for post-calcination for template elimination, instead permitting aqueous removal with water. The influence of the sodium salts on the characteristics of CoOx/SiO2 spheres was investigated by means of XRD, nitrogen physisorption, SEM/TEM, ICP-MS, UV-Vis, XPS and H2-TPR. On the basis of the experimental results, a possible mechanism on the formation of hollow and mesoporous spheres was proposed. The CoOx/SiO2 spheres were tested as catalysts for toluene oxidation. The mesoporous CoOx/mSiO2 was found to exhibit superior activity to hollow CoOx/hSiO2, probably attributed to a combination of several factors, including the predominant existence of a Co3O4 active phase, high surface Co3+ content, and easy reducibility of Co3+ at low temperature.

Original languageEnglish
Pages (from-to)24304-24313
Number of pages10
JournalRSC Advances
Volume6
Issue number29
DOIs
StatePublished - 26 Feb 2016

Keywords

  • COBALT OXIDE
  • PREFERENTIAL OXIDATION
  • SILICA MATERIALS
  • CARBON-MONOXIDE
  • AEROSOL ROUTE
  • WASTE POWDER
  • TEMPERATURE
  • COMBUSTION
  • PERFORMANCE
  • CO

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