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Show The efficiency of methanol in NO oxidation is slightly higher than that of H20 2• However, H20/CH30H mixtures are more efficient in NO oxidation than each component individually due to more easy fonnation of OH radicals from H20 2• The presence of H20 2 in mixtures with CH30H is capable of decreasing the amount of CO fonred from CH30H. Since methanol is less expensive than hydrogen peroxide, one can add as much CH30H as possible within CO limits, and then add enough H20 2 to obtain target NO conversion. The injection of H20 2 and H20/CH30H mixtures can substitute for methanol injection in the CombiNOx process or can be used for tail-end NO removal in combination with other upstream NO control rrethods. Assuming 65-75% NO-to-N02 conversion by H20/CH30H injection in coal flue gas and taking into account pilot-scale results in other CombiNOx steps, the total process will remove over 90% NOx• Modeling qualitatively explains the experimental data. In the homogeneous H20 2 decomposition the total amount of OH radicals increases due to dissociation: H20 2 + M -. 2 OH + M. The most important reactions responsible for NO removal in the temperature range of 700-1100 ACKNOWLEDGMENT This work was supported by the U.S. Department of Energy under a grant No. DE-FG05- 93ER81538. REFERENCES Azuhata, S, Akimoto, H. and Hishimura, Y. (1982) Effect of H20 2 on Homogeneous Gas Phase NO Reduction with NH3• AlChE Journal, 28, 7-11. Chang, S.G. and Lee, G.C. (1992) LBL PhoSNOX Process for Combined Removal of S02 and NOx from Flue Gas. Environ. Progress, 11, 66-73. 17 - |
