* 발표자 : 김강영
* 제목 : Effect of Alkaline&8211earth Metal Carbonate Salts on CO2 absorption on NaNO3&8211MgO Absorbent
* 내용 : MgO-based CO2 absorbents is operated in the intermediate temperature of 300~500℃. Typically, these absorbents are composed of MgO and a promoter. NaNO3 or other alkali nitrates have been explored as the promoter. Although the overall reaction mechanisms have been clarified by previous studies as that the promoter is the medium for the reaction between CO2 and MgO, many details are not yet clear. We believe that clear elucidation of the details reaction mechanism is the first step for the improvement of the performance of the MgO-based absorbents.
The absorption isotherms of NaNO3&8211promoted MgO absorbents in the literature and our own data shows sigmoidal curves. We interpret this as a signature of auto&8211catalyzed kinetics of CO2 absorption. We further conjectured that this behaviour may arise from the growth kinetics of MgCO3, which involves nucleation and growth steps. In order to verify this idea, we have prepared various NaNO3-MgO absorbent samples with different alkaline&8211earth metal carbonates added. The carbonate salts did not affect the CO2 absorption capacity of MgO, but they appeared to enhance the CO2 absorption kinetics. However, the facilitation effects of the added carbonate disappears from the second cycle of the absorption-desorption cycles. These observations are consistent with the proposed mechanism of nucleation and growth of MgCO3 crystals. Further, our observations indicate that the growth of MgCO3 is the rate-determining steps.
* 발표자 : 박현욱
* 제목 : Ultrasound-assisted Polyol Synthesis of Well-dispersed Pt Nanoparticles on Titanium Carbide and Their Electrochemical Performance
* 내용 : In this study, we report the Ultrasound-assisted Polyol Synthesis (UPS) of well-dispersed Pt Nanoparticles (NPs) on Titanium Carbide (TiC) and their electrochemical performance for Methanol Oxidation Reaction (MOR) and Oxygen Reduction Reaction (ORR). In order to prepare Pt/TiC samples, metal precursors and TiC were dispersed in ethylene glycol and irradiated by ultrasound for 3 h. Through the structural analyses of Pt/TiC, we found that samples have uniform particle size (4~5 nm) and well-dispersed Pt NPs on TiC. Electrochemical performance of samples was investigated by Rotating Disk Electrode (RDE) measurement. Compared with commercial Pt/C, Pt/TiC showed the enhanced ORR and MOR activity in acidic media. In conclusion, we demonstrated that the Strong Metal-Support Interaction (SMSI) effect between Pt and TiC leads the enhanced electrocatalytic performance and durability.