Fourier Transform Infrared Photoacoustic Spectroscopy Characterization of Sulfur-Oxygen Species Resulting from the Reaction of SO 2 with CaO and CaCO 3

Abstract

Fourier transform infrared photoacoustic spectroscopy (FT-IR/PAS) has been used to investigate the reaction of SO₂, in He with CaO and CaCO₃ particles at temperatures between 25 and 900°C. The reaction of SO₂ with CaO occurs at 25°C, while the reaction of CaCO₃ with SO₂ is first evident at 550°C. The initial product of both of these reactions is CaSO₃. The CaSO₃ then further reacts with SO₂ to form CaSO₄, CaS₂O₃, and CaS at higher temperatures. At 900°C and above, the net production of SO₄⁼ and S₂O₃⁼ is decreased because of the decomposition of SO₃⁼. FT-IR/PAS depth-profiling experiments indicate the formation of a reaction-limiting product layer of SO₃⁼ and SO₄⁼ from the above reactions on the surface of the CaO and CaCO₃ particles.