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Keywords:

  • dehydrogenation;
  • phosphorus;
  • cerium;
  • alkanes;
  • surface analysis

Abstract

Surface- and bulk-phosphated ceria catalysts were prepared and studied in propane oxidative dehydrogenation (ODH) at 823 and 873 K. The catalysts were characterized by N2 adsorption at 77 K, XRD, TEM, and diffuse reflectance IR Fourier transform (DRIFT), Raman, X-ray photoelectron (XPS), and energy dispersive X-ray (EDX) spectroscopies. Both series of catalysts presented an increase in the ODH selectivity with respect to pure ceria mainly at the expense of total oxidation selectivity. Thus, the selectivity to propene was approximately 74 % with surface-phosphated catalysts and 62 % with bulk-phosphated catalysts. For the surface-phosphated samples, P is confined to the surface and subsurface regions of the ceria particles, whereas P is also dispersed in the bulk of the oxide in the bulk-phosphated samples. Finally, all the characterization techniques led us to the conclusion that Ce4+ cations that interact with P are responsible for the observed increase in the ODH.