Application of sulfur impregnated activated carbons for the control of mercury emissions
- Univ. of Pittsburgh, PA (United States). Dept. of Civil and Environmental Engineering
- Dept. of Energy, Pittsburgh, PA (United States). Federal Energy Technology Center
The dynamics of granular activated carbon (GAC) adsorbers for the uptake of vapor-phase mercury was evaluated as a function of temperature, influent mercury concentration, and empty bed contact time. Sulfur-impregnated carbons exhibited enhanced mercury removal efficiency over virgin carbon due to formation of mercuric sulfide on the carbon surface. The effect of the sulfur impregnation method on mercury removal efficiency was examined through experiments conducted on commercially available sulfur-impregnated carbon (HGR) and carbon impregnated with sulfur in the laboratory (BPL-S). Although HGR and BPL-S possess similar sulfur contents, BPL-S is impregnated at a higher temperature which promotes a more uniform distribution of sulfur in the GAC pore structure. At low influent mercury concentrations and low temperatures, HGR and BPL-S performed similarly in the removal of mercury vapor. However, as the temperature was increased above the melting point of sulfur, the performance of HGR deteriorated significantly, while the performance of BPL-S slightly improved. For both HGR and BPL-S, the observed dynamic mercury adsorptive capacities were far below the capacities predicted by the stoichiometry of mercuric sulfide formation. In HGR carbon the sulfur is very accessible, but agglomeration which occurs at high temperatures causes the sulfur to become relatively unreactive. In BPL-S carbon, on the other hand, the sulfur remains in a highly reactive form, but its location deep in the internal pores makes it relatively inaccessible and susceptible to blockage by HgS formation. Impregnation temperature and the initial sulfur to carbon ratio (SCR) during the impregnation are the two key control parameters for the preparation of these new (BPL-S) sorbents. Higher impregnation temperatures can significantly enhance mercury removal capacity for adsorbents derived either from virgin or re-generated activated carbons. Large fraction of active sulfur atoms that are created at higher temperatures, together with high surface area, and predominance of meso-pores, are responsible for high efficiency of these sorbents. Because the SCR did not have nearly as pronounced impact on the performance as impregnation temperature, it can be concluded that the actual form of sulfur, rather than the total sulfur content, is a crucial parameter governing the mercury chemisorption process. In general, these new adsorbents show superior characteristics for mercury control when compared to virgin carbons and commercially available sulfur impregnated carbon.
- DOE Contract Number:
- FG22-96PC96212
- OSTI ID:
- 349158
- Report Number(s):
- CONF-980985-; ISBN 1-890977-15-2; TRN: IM9924%%158
- Resource Relation:
- Conference: 15. annual international Pittsburgh coal conference, Pittsburgh, PA (United States), 14-18 Sep 1998; Other Information: PBD: 1998; Related Information: Is Part Of Fifteenth annual international Pittsburgh coal conference: Proceedings; PB: [1500] p.
- Country of Publication:
- United States
- Language:
- English
Similar Records
Activated carbon based technology for the control of mercury emission from coal-fired power plants
Evaluation of carbon-based substrates for the production of economical mercury sorbents