Roll-up effect of sulfur dioxide adsorption on zeolites FAU 13X and LTA 5A
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The roll-up effect occurs as a result of the displacement of SO2 with H2O(g) when sulfur dioxide from humid flue gas is adsorbed by zeolites. It is mainly affected by SiO2/Al2O3 ratio (S/A) of zeolites, despite lack of detailed studies on use of hydrophilic zeolite. In this study, two zeolites of FAU 13X (S/A of 1.77) and LTA 5A (S/A of 1.51) were used to explore their roll-up effects using the breakthrough curve method. It is shown that the zeolite structure significantly influences the roll-up effect. The roll-up effect of FAU 13X is more significant than that of LTA 5A at the same water vapor content. The maximum roll-up ratio (η) for LTA 5A and FAU 13X are, respectively, 1.23 and 2.55 within the water vapor content range of 0.9–2.4%. Moreover, η of FAU 13X tends to decrease more rapidly than that of LTA 5A with increasing temperature or decreasing adsorption gas pressure. The presence of oxygen inhibits the roll-up effect and increases the breakthrough time of SO2. For the acid-modified zeolite, there is a positive correlation between η and concentration of Ca2+ or Na+ on zeolite surface, indicating obvious impact of cations on the roll-up effect.
KeywordsZeolite SO2 Roll-up effect Adsorption
The authors wish to express their thanks to the National Natural Science Foundation of China (Nos. 51234008 and 51174230) for financial support. This work was also financially supported by the Co-Innovation Center for Clean and Efficient Utilization of Strategic Metal Mineral Resources.