Abstract
Fourier transform photoacoustic and diffuse reflectance spectroscopies (FT-IR-PAS and -DRS) have been used in <i>situ</i> to monitor the reaction of SO<sub>2</sub> (1.5% in N<sub>2</sub>) with particulate CaCO<sub>3</sub> at temperatures up to 400°C (PAS) and 690°C (DRS). The PA spectra indicate that at 360°C SO<sub>2</sub> is physisorbed on the CaCO<sub>3</sub> surface. This species is readily desorbed by N<sub>2</sub> purging. Under continuous SO<sub>2</sub>/N<sub>2</sub> exposure at 400°C and above, the physisorbed species is shown by the DR data to be converted first to oxygen-bound and then to nonspecifically bound pyramidal SO<sub>3</sub><sup>−</sup> Reaction of the SO<sub>3</sub><sup>−</sup> with SO<sub>2</sub> to form SO<sub>4</sub><sup>−</sup> begins at 400°C and is essentially complete at 690°C. The DR data further indicate that for the SO<sub>4</sub><sup>−</sup>: (1) at temperatures between 400 and 640°C a monodentate C<sub>3ν</sub> species forms; (2) above 640°C the SO<sub>4</sub><sup>−</sup> ion has nearly <i>T<sub>d</sub></i> symmetry; and (3) upon subsequent cooling, the SO<sub>4</sub><sup>−</sup> exhibits the characteristics of a chelating <i>C</i><sub>2ν</sub> species.
PDF Article
More Like This
Cited By
You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.
Contact your librarian or system administrator
or
Login to access Optica Member Subscription