Nano-CaCO3 particles were surface-coated with SiO2 by the sol-gel method and used as the high temperature CO2 adsorption material.CaCO3 samples prepared at 60—90℃ were characterized with TEM, EDS and XRD methods and...Nano-CaCO3 particles were surface-coated with SiO2 by the sol-gel method and used as the high temperature CO2 adsorption material.CaCO3 samples prepared at 60—90℃ were characterized with TEM, EDS and XRD methods and the initial and final decomposition temperature were determined with TGA.The CO2 adsorption ratio and carbonation-calcination characteristics were evaluated in a 12 mm fixed bed reactor.The analytical results showed that there was an amorphous SiO2 film formed on the surface of nano-CaCO3,and the atomic ratio of Si to Ca is 1∶39.The initial and final decomposition temperatures were 595—620℃ and 800—820℃ respectively.The maximum CO2 adsorption ratio of SiO2 coated with nano-CaCO3 was 92.1% at 600℃with a 10% increase as compared with the uncoated nano-CaCO3 particles.After 20 cyclic carbonation and calcination runs, CO2 adsorption ratio of the SiO2 coated samples was 63%.The XRD analysis illustrated that the crystal type of nano-CaCO3 had no change after 20 cyclic runs.展开更多
Oxidation treatment on the adsorption and the stability of Hg on activated carbon （AC） was inrestigated. Both MnO2-AC and FeCl3-AC were produced during oxidation treatment. The measurement of modified AC＇s mercury ...Oxidation treatment on the adsorption and the stability of Hg on activated carbon （AC） was inrestigated. Both MnO2-AC and FeCl3-AC were produced during oxidation treatment. The measurement of modified AC＇s mercury adsorption capacity was conducted in a simulated coal-fired flue gas by adsorbing test apparatus. TCLP and column leaching methods were used to test the stability of mercury adsorbed on ACs. The results indicate that the oxidation treatment changed the pore structure of the AC and modified the carbon surface by creating chemical components such as MnO4^-, Mn^4＋, O, NO^3-, Fe^3＋, Cl^-, etc. The Hg sorption capacity on MnO2-AC or FeCl3-AC was about three times higher than that of untreated carbon. In addition, the mercury control cost of each of the formers was about the half cost of the untreated carbon. The stability of Hg absorption was studied, it found that mercury adsorbed on the oxidation treated AC was not better than that of untreated carbon. It could concluded that the insoluble form of Hg is very important to the stability of mercury adsorbed on AC. This study suggests that the FeCl3-AC is the best absorbent for Hg with high adsorption capacity, better Hg adsorption stability in leaching environment, and lower cost among the three ACs tested.展开更多
文摘Nano-CaCO3 particles were surface-coated with SiO2 by the sol-gel method and used as the high temperature CO2 adsorption material.CaCO3 samples prepared at 60—90℃ were characterized with TEM, EDS and XRD methods and the initial and final decomposition temperature were determined with TGA.The CO2 adsorption ratio and carbonation-calcination characteristics were evaluated in a 12 mm fixed bed reactor.The analytical results showed that there was an amorphous SiO2 film formed on the surface of nano-CaCO3,and the atomic ratio of Si to Ca is 1∶39.The initial and final decomposition temperatures were 595—620℃ and 800—820℃ respectively.The maximum CO2 adsorption ratio of SiO2 coated with nano-CaCO3 was 92.1% at 600℃with a 10% increase as compared with the uncoated nano-CaCO3 particles.After 20 cyclic carbonation and calcination runs, CO2 adsorption ratio of the SiO2 coated samples was 63%.The XRD analysis illustrated that the crystal type of nano-CaCO3 had no change after 20 cyclic runs.
基金The National Natural Science Foundation of China (No. 50476056) the Hi-Tech Research and Development Program (863) ofChina (No. 2005AA520080)
文摘Oxidation treatment on the adsorption and the stability of Hg on activated carbon （AC） was inrestigated. Both MnO2-AC and FeCl3-AC were produced during oxidation treatment. The measurement of modified AC＇s mercury adsorption capacity was conducted in a simulated coal-fired flue gas by adsorbing test apparatus. TCLP and column leaching methods were used to test the stability of mercury adsorbed on ACs. The results indicate that the oxidation treatment changed the pore structure of the AC and modified the carbon surface by creating chemical components such as MnO4^-, Mn^4＋, O, NO^3-, Fe^3＋, Cl^-, etc. The Hg sorption capacity on MnO2-AC or FeCl3-AC was about three times higher than that of untreated carbon. In addition, the mercury control cost of each of the formers was about the half cost of the untreated carbon. The stability of Hg absorption was studied, it found that mercury adsorbed on the oxidation treated AC was not better than that of untreated carbon. It could concluded that the insoluble form of Hg is very important to the stability of mercury adsorbed on AC. This study suggests that the FeCl3-AC is the best absorbent for Hg with high adsorption capacity, better Hg adsorption stability in leaching environment, and lower cost among the three ACs tested.
