Interactive mechanism of plasma-assisted CO2 capture for calcium looping cycle via in-situ DRIFTS

Abstract

Plasma-assisted calcium looping (CaL) process has been proposed for improvement of CO2 capture technique. The conventional CaL process has a critical drawback such as low energy efficiency associated with a high temperature required for both the capture and release of CO2. In the present study, the plasma-assisted CO2 capture was proposed to improve the reactivity of CaO carbonation. An in-situ DRIFTS reactor was designed to investigate the carbonation reactivity in the presence of plasma on the CaO. The mixture of CO2 and He was injected into the reactor and the plasma was generated on the CaO surface at the fixed input power of 20 W. The IR spectra were obtained according to the temperature ranging from 100 to 500℃. In general, the reaction of CO2 with CaO is thermodynamically more favorable than that with Ca(OH)2. When the plasma was applied, however, the reaction pathway was changed to enhance the reaction of CO2 with Ca(OH)2. The evidence on the change of reaction pathway was validated by detecting the H2O band at the temperate higher than 200℃ under the plasma, even though the H2O band was removed after the calcination at 900℃. Consequently, the CO2 intensity was notably decreased by 33.33 % at 500 °C, which implied that the reactivity of CaO carbonation was improved. Based on the in-situ DRIFTS analysis, a lab-scale plasma reactor was designed for the CaO carbonation with the plasma-excited CO2. The effect of CO2 concentration on the CO2 conversion and energy efficiency was presented in the plasma-assisted CaL process.