Formation of sulfite-like species on Cr2O3 after SO2 chemisorption

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

SURFACE SCIENCE

ELSEVIER SCIENCE BV

Año: 2010 vol. 605 p. 489 - 493

0039-6028

The adsorption of sulfur dioxide (SO2) on polycrystalline Cr2O3 was experimentally investigated usingtemperature-programmed desorption (TPD). The chemisorption of SO2 on the (0001) surface was alsostudied using theoretical methods. Different adsorption geometries were explored for SO2 adsorption on theα-Cr2O3 (0001) surface. Two similar adsorption configurations were found to be the most stable withchemisorption energies of−3.09 and−2.79 eV/molecule. In both calculated stable adsorption configurationsthe appearance of sulfite-like species is predicted on the (0001) surface after adsorption. It is important toemphasize that these results are predicted only within the DFT+U framework. Under these conditions anddespite great efforts, no stable sulfate-like geometry was found on this surface. The TPD spectrum exhibit adesorption peak at Tp≈870 °C with a heating rate of β≈0.12 °C/s. The desorption energy calculated by theanalysis 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 ourknowledge, this is the first theoretical study of SO2 adsorption on the Cr2O3 (0001) surface