1. A laboratory study of Hg oxidation catalyzed by SCR catalysts Karin Madsen on 05.10.2010 at CHEC Annual Day Anker Degn Jensen Joakim Reimer Thøgersen Flemming Frandsen

2. DTU Chemical Engineering Technical University of Denmark Outline •Background •Laboratory Study •Conclusions

3. DTU Chemical Engineering Technical University of Denmark Background •1930 tons of mercury was emitted in 2005 (Pacyna, 2010) –45% comes from combustion of fossil fuels •Existing air pollution control devices offers an economically feasible option for mercury control •Mercury species in flue gases from power plants –Hg 0 : Volatile, difficult to capture –Hg 2+ : Water soluble, can be captured in a wet scrubber –Hg p : Can be captured in particulate control devices •Mercury speciation is highly dependent on coal type/rank and operating conditions

4. DTU Chemical Engineering Technical University of Denmark Mercury oxidation and the SCR •Mercury is oxidized by halogens in the flue gas •(Potential) net reaction Hg 0 + 2 HCl + 1/2 O 2 = HgCl 2 + H 2 O •SCR catalysts for NOx-control also have catalytic activity on the mercury oxidation –The combination SCR + wet FGD can offer >90% mercury capture

5. DTU Chemical Engineering Technical University of Denmark Laboratory Setup at Topsoe A/S

6. DTU Chemical Engineering Technical University of Denmark Mercury oxidation and Chlorine

7. DTU Chemical Engineering Technical University of Denmark Mercury Oxidation and Ammonia

8. DTU Chemical Engineering Technical University of Denmark Mercury Oxidation: Laboratory versus Pilot-scale data

9. DTU Chemical Engineering Technical University of Denmark Conclusion: Close Gap between Laboratory and Pilot- Scale Data •Difference in gas matrix –Laboratory Simulated flue gas containing Hg 0, O 2, H 2 O, NH 3, HCl and N 2 –Pilot Real flue gas from subbituminous coal combustion including NO, SO 2, and fly ash •Factor 10-20 difference in catalyst activity must be due to difference in gas matrix •Future work involves testing of more complex gas matrices including NO and SO 2