Formation of sulfite-like species on Cr2O3 after SO2 chemisorption

V. A. RANEA; S. N. HERNÁNDEZ; S. MEDINA; I. M. IRURZUN; I. D. CORIA ; E. E. MOLA

SURFACE SCIENCE

ELSEVIER SCIENCE BV

Año: 2011 p. 489 - 493

0039-6028

The adsorption of sulfur dioxide (SO2) on polycrystalline Cr2O3 was experimentally investigated using temperature-programmed desorption (TPD). The chemisorption of SO2 on the (0001) surface was also studied using theoretical methods. Different adsorption geometries were explored for SO2 adsorption on the α-Cr2O3 (0001) surface. Two similar adsorption configurations were found to be the most stable with chemisorption energies of−3.09 and−2.79 eV/molecule. In both calculated stable adsorption configurations the appearance of sulfite-like species is predicted on the (0001) surface after adsorption. It is important to emphasize that these results are predicted only within the DFT+U framework. Under these conditions and despite great efforts, no stable sulfate-like geometry was found on this surface. The TPD spectrum exhibit a desorption peak at Tp≈870 °C with a heating rate of β≈0.12 °C/s. The desorption energy calculated by the analysis given by Redhead and Adams, assuming the rate of desorption is given by a Polanyi–Wigner equation, is ≈ −3.12 eV. This value is in good agreement with the predicted one using DFT+U calculations. To our knowledge, this is the first theoretical study of SO2 adsorption on the Cr2O3 (0001) surface.