SO2 rapid adsorption and desorption over activated semi coke in a rotary reactor

Abstract

Herein, activated semi coke (ASC) adsorbents were prepared and tested for SO2 adsorption-desorption process in a rotary reactor. The experiment results showed that the nitric acid activated semi coke (ASC-1) had a higher SO2 adsorption capacity and a better SO2 removal ability in the SO2 adsorption-desorption dynamic process. And the SO2 adsorption efficiency of ASC-1 in the dynamic SO2 removal process was increased from 57.5% to 88.3% at 200 °C with the extension of desorption time from 60 s to 180 s. Increasing the desorption temperature was an effective method to improve SO2 removal efficiency in the rotary reactor. The SO2 adsorption efficiency of ASC could be improved from 52.5% to 80.7% with the desorption temperature increasing from 100 °C to 300 °C. Moreover, the mechanisms of SO2 adsorption-desorption dynamic process over ASC in rotary reactor at different temperatures were also summarized. There were two desorption paths for SO2 species adsorbed on the ASC surface under the purge of desorption gas CO. One of the paths was that the weakly adsorbed SO2 and some –SO3- species were directly desorbed from ASC surface under the purge of CO, which was the dominant SO2 desorption path. And the other path, which was not activated at low temperature (<200 °C), was that sulfate and part of sulfite species were combined with CO first, then decomposed and desorbed from ASC in the form of SO2 under not too high temperature, while the CO involved in the combination was released in the form of CO2.