CaO-based sorbent is considered to be a promising candidate for capturing CO_2 at high temperature. However,the adsorption capacity of CaO decreases sharply with the increase of the carbonation/calcination cycles. In ...CaO-based sorbent is considered to be a promising candidate for capturing CO_2 at high temperature. However,the adsorption capacity of CaO decreases sharply with the increase of the carbonation/calcination cycles. In this study, CaO was derived from calcium acetate(CaAc_2), which was doped with different elements(Mg, Al,Ce, Zr and La) to improve the cyclic stability. The carbonation conversion and cyclic stability of sorbents were tested by thermogravimetric analyzer(TGA). The sorbents were characterized by N_2 isothermal adsorption measurements, scanning electron microscopy(SEM) and X-ray diffraction(XRD). The results showed that the cyclic stabilities of all modified sorbents were improved by doping elements, while the carbonation conversions of sorbents in the 1st cycle were not increased by doping different elements. After 22 cycles, the cyclic stabilities of CaO–Al, CaO–Ce and CaO–La were above 96.2%. After 110 cycles, the cyclic stability of CaO–Al was still as high as 87.1%. Furthermore, the carbonation conversion was closely related to the critical time and specific surface area.展开更多
The presence of SO_(2) display significant effect on the mercury(Hg) adsorption ability of carbon-based sorbent. Yet the adsorption and oxidation of SO_(2) on carbon with oxygen group, as well as the roles of differen...The presence of SO_(2) display significant effect on the mercury(Hg) adsorption ability of carbon-based sorbent. Yet the adsorption and oxidation of SO_(2) on carbon with oxygen group, as well as the roles of different sulfur oxide groups in Hg adsorption have heretofore been unclear. The formation of sulfur oxide groups by SO_(2) and their effects on Hg adsorption on carbon was detailed examined by the density functional theory. The results show that SO_(2) can be oxidized into SO_(2) by oxygen group on carbon surface. Both C-SO_(2) and C-SO_(2)can improve Hg adsorption on carbon site, while the promotive effect of C-SO_(2) is stronger than C-SO_(2). Electron density difference analyses reveal that sulfur oxide groups enhance the charge transfer ability of surface unsaturated carbon atom, thereby improving Hg adsorption. The experimental results confirm that surface active groups formed by SO_(2) adsorption is more active for Hg adsorption than the groups generated by SO_(2).展开更多
基金Supported by Capture CO_2 and Storage Technology Jointly Studied by USA and China(2013DFB60140-04)Northwest University Graduate Innovative Talent Training Project(YZZ12036)
文摘CaO-based sorbent is considered to be a promising candidate for capturing CO_2 at high temperature. However,the adsorption capacity of CaO decreases sharply with the increase of the carbonation/calcination cycles. In this study, CaO was derived from calcium acetate(CaAc_2), which was doped with different elements(Mg, Al,Ce, Zr and La) to improve the cyclic stability. The carbonation conversion and cyclic stability of sorbents were tested by thermogravimetric analyzer(TGA). The sorbents were characterized by N_2 isothermal adsorption measurements, scanning electron microscopy(SEM) and X-ray diffraction(XRD). The results showed that the cyclic stabilities of all modified sorbents were improved by doping elements, while the carbonation conversions of sorbents in the 1st cycle were not increased by doping different elements. After 22 cycles, the cyclic stabilities of CaO–Al, CaO–Ce and CaO–La were above 96.2%. After 110 cycles, the cyclic stability of CaO–Al was still as high as 87.1%. Furthermore, the carbonation conversion was closely related to the critical time and specific surface area.
基金supported by the National Natural Science Foundation of China (No. 51722407 )the Science and Technology Project of Hunan Province (No. 2019RS3006)the Project of Innovation-driven Plan in Central South University (No. 20180018050001)。
文摘The presence of SO_(2) display significant effect on the mercury(Hg) adsorption ability of carbon-based sorbent. Yet the adsorption and oxidation of SO_(2) on carbon with oxygen group, as well as the roles of different sulfur oxide groups in Hg adsorption have heretofore been unclear. The formation of sulfur oxide groups by SO_(2) and their effects on Hg adsorption on carbon was detailed examined by the density functional theory. The results show that SO_(2) can be oxidized into SO_(2) by oxygen group on carbon surface. Both C-SO_(2) and C-SO_(2)can improve Hg adsorption on carbon site, while the promotive effect of C-SO_(2) is stronger than C-SO_(2). Electron density difference analyses reveal that sulfur oxide groups enhance the charge transfer ability of surface unsaturated carbon atom, thereby improving Hg adsorption. The experimental results confirm that surface active groups formed by SO_(2) adsorption is more active for Hg adsorption than the groups generated by SO_(2).
