Abstract
Using X-ray photoelectron spectroscopy (XPS), the chemisorption of SO 2 on CaO(100) has been studied in the temperature range from 25 to 400° C. The chemical state of sulfur has been identified as that of sulfate. The kinetics of SO 2 chemisorption on CaO are discussed. The binding states of Fe and Na on CaO were determined to be Fe 2+ and Na + respectively. The effect of the metal adsorbates (Fe, Na) on the chemisorption of SO 2 was also studied. In the presence of Fe (coverage ⩾ 0.5 monolayer), both sulfate and sulfide were observed; in the presence of Na, however, only sulfate was observed. The saturated amount of sulfate formed depends on the Fe coverage, but it is independent of the Na coverage. At low Fe coverages (< 0.5 monolayer), there is a large increase in the rate of sulfate formation at low SO 2 exposures (< 3 L). This increase is explained by the “activation” of SO 2 chemisorption sites by Fe adatoms. At increased Fe coverage, the rate of sulfate formation decreases due to the blocking effect of the Fe islands formed on the surface. Similarly, the effect of Na adatoms on SO 2 uptake can also be explained by the same mechanism. However, the inability of the Na islands to block the SO 2 chemisorptive sites and the lack of chemisorptive bond formation between SO 2 and Na are explained by the diffusion of SO 2 through the Na adlayer.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
