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Keywords:

  • Hydrotalcite;
  • Vanadium;
  • Mixed oxides;
  • Layered compounds;
  • Cracking;
  • IR spectroscopy;
  • Raman spectroscopy

Abstract

The interaction of VO2+ species with Mg6Al2(OH)16(CO3)·n(H2O) hydrotalcite (HTC) and the corresponding HTC-derived mixed oxide (MO, obtained by calcination of HTC at 800 °C) is reported. Vanadium was loaded (2–20 wt.-%) onto HTC and onto MO using an aqueous solution of VOSO4. After the spontaneous reaction, solids were filtered, treated at 120 °C and then characterised. The characterisation techniques used include spectroscopic, structural, textural and thermal analyses, such as FTIR, Raman, UV/Vis DRS, XRD, BET, EPR, TG/DTA and TPO/TPR. In this work, the nature of the vanadium species on HTC and MO as a function of vanadium loading was studied. The presence of VIII species in the layers of HTC and anionic VV species in the interlayers have been proposed, whereas on MO VIV species are easily oxidised by air producing oligomerised VV supported species.