Resource utilization of high-concentration SO2 for sulfur production over La-Ce-Ox composite oxide catalyst

Abstract

Sulfur dioxide is one of the main causes of air pollution such as acid rain and photochemical smog, and its pollution control and resource utilization have become important research directions. La2O3 was incorporated into CeO2 to enhance the surface basicity of La-Ce-Ox catalyst and increase the concentration of chemisorbed oxygen, thereby promoting the improvement of catalytic performance of SO2 reduction by CO. Results have showed that the incorporation of La2O3 would not only increase the concentration of chemisorbed oxygen and hydroxyl on the catalyst surface, but also increase the basicity of the catalyst, thereby facilitating the adsorption of SO2 on the catalyst surface. The 12%La-Ce-Ox was the optimal catalyst, and its SO2 conversion at 350–400 ℃ reached close to 100%, and the sulfur yield at this temperature range was higher than 93%. Finally, according to the in situ infrared diffuse reflectance spectrum, it was found that the main reaction intermediates of 12%La-Ce-Ox in the catalytic reduction of SO2 were weakly adsorbed sulfate, SO32−, non-coordinating CO32−, monodentate carbonate, and CO, so the catalytic reaction followed the L–H and E-R mechanisms simultaneously.