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Trace Na2CO3 Addition to Limestone Inducing High-Capacity SO2 Capture
Rui Han1, Fei Sun1, Jihui Gao1
1School of Energy Science and Engineering, Harbin Institute of Technology , Harbin 150001, China.
Environmental Science & Technology
|October 10, 2017
Summary
Trace amounts of sodium carbonate (Na2CO3) significantly boost limestone sulfation, unlike previous high-dose methods. This novel approach optimizes sorbent pore structure for enhanced reactivity and offers economic benefits in combustion systems.
Area of Science:
- Chemical Engineering
- Materials Science
- Environmental Science
Background:
- Indirect sulfation of limestone is crucial for capturing sulfur dioxide (SO2) in fluidized-bed combustion.
- Traditional methods using sodium carbonate (Na2CO3) require high additive concentrations (∼4.0 mol %), leading to adverse effects and increased costs.
Purpose of the Study:
- To investigate the effect of trace Na2CO3 on limestone sulfation.
- To elucidate the mechanism by which trace Na2CO3 enhances sulfation.
- To explore the potential of other metal salts as additives.
Main Methods:
- Experimental analysis of limestone sulfation with varying concentrations of Na2CO3.
- Characterization of sorbent surface area and pore size distribution.
- Investigation of the role of pore structure and product layer diffusion.
Main Results:
- Trace Na2CO3 (0.1 mol %) significantly enhances limestone sulfation.
- Optimized pore structure (peaks at ∼4 nm and ∼140 nm) increases surface area and reactivity.
- Na2CO3 influences reactivity by tuning pore structure (<0.5 mol %) and promoting diffusion (>0.5 mol %).
- Other metal salts like CaCl2 and NaCl also enhance sulfation.
Conclusions:
- Trace metal salt addition is an effective strategy to enhance limestone sulfation.
- This approach offers significant engineering and economic advantages for industrial applications.
- The findings pave the way for more efficient and cost-effective SO2 capture technologies.