title: Feasibility of CO₂/SO₂ uptake enhancement of calcined limestone modified with rice husk ash during pressurized carbonation.
abstract: The calcination/carbonation cycle using calcium-based sorbents appears to be a viable method for carbon dioxide (CO₂) capture from combustion gases. Recent attempts to improve the CO₂/SO₂ uptake of a calcium-based sorbent modified by using rice husk ash (RHA) in the hydration process have succeeded in enhancing its effectiveness. The optimal mole ratio of RHA to calcined limestone (M(Si/Ca)) was adjusted to 0.2. The cyclic CO₂ capture characteristics and the SO₂ uptake activity of the modified sorbent were evaluated in a calcination/pressurized carbonation reactor system. Scanning electron microscope (SEM) images and X-ray diffraction (XRD) spectrum of the sorbent were also taken to supplement the study. The results showed that the carbonation conversion was greatly increased for the sorbent with M(Si/Ca) ratio of 0.2. For this sorbent formulation the optimal operating conditions were 700-750 °C and 0.5-0.7 MPa. CO₂ absorption was not proportional to CO₂ concentration in the carbonation atmosphere, but was directly related to reaction time. The CO₂ uptake decreased in the presence of SO₂. SO₂ uptake increased, and the total calcium utilization was maintained over multiple cycles. Analysis has shown that the silicate component is evenly or well distributed, and this serves as a framework to prevent sintering, thus preserving the available microstructure for reaction. The sorbent also displayed high activity to SO₂ absorption and could be used to capture CO₂ and SO₂ simultaneously.
authors: School of Energy and Environment, Southeast University, Nanjing 210096, PR China.
authors: Huichao
authors: H
authors: Chen
authors: Changsui
authors: C
authors: Zhao
authors: Qiangqiang
authors: Q
authors: Ren
mesh_terms: D000042:Absorption; D000393:Air Pollutants / Q000737:chemistry*; D002119:Calcium Carbonate / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry*; D052918:Environmental Restoration and Remediation / Q000379:methods*; D005240:Feasibility Studies; D005579:Fossil Fuels; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D012275:Oryza / Q000737:chemistry*; D011312:Pressure; D013458:Sulfur Dioxide / Q000737:chemistry*; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D000393:Air Pollutants; D005579:Fossil Fuels; D013458:Sulfur Dioxide; D002245:Carbon Dioxide; D002119:Calcium Carbonate