Catalytic reduction of nitrogen oxides

TABLE 25-25 Advantages and Disadvantages of Selective Catalytic Reduction of Nitrogen Oxides... 

Selective Catalytic Reduction of Nitrogen Oxides The traditional approach to reducing ambient ozone concentrations has been to reduce VOC emissions, an ozone precurssor. In many areas, it has now been recognized that ehmination of persistent exceedances of the National Ambient Air Qnality Standard for ozone may reqnire more attention to reductions in the other ingredients in ozone formation, nitrogen oxides (NOJ. In such areas, ozone concentrations are controlled by NO rather than VOC emissions. 

Reactions involving the catalytic reduction of nitrogen oxides are of major environmental importance for the removal of toxic emissions from both stationary and automotive sources. As shown in this section electrochemical promotion can affect dramatically the performance of Rh, Pd and Pt catalysts (commonly used as exhaust catalysts) interfaced with YSZ, an O2 ion conductor. The main feature is strong electrophilic behaviour, i.e. enhanced rate and N2 selectivity behaviour with decreasing Uwr and , due to enhanced NO dissociation. 

It has been reported that titanium supported vanadium catalyst is active for ammonia oxidation at temperatures above 523 K [2,3]. Also, supported vanadium oxides are known to be efficient catalyst for the catalytic reduction of nitrogen oxides (NO ) in the presence of ammonia [4]. This work investigates the nanostructured vanadia/Ti02 for low temperature catalytic remediation of ammonia in air. 

Less, but still significant, information is available on the surface chemistry of other nitrogen oxides. In terms of N20, that molecule has been shown to be quite reactive on most metals on Rh(110), for instance, it decomposes between 60 and 190 K, and results in N2 desorption [18]. N02 is also fairly reactive, but tends to convert into a mixed layer of adsorbed NO and atomic oxygen [19] on Pd(lll), this happens at 180 K, and is partially inhibited at high coverages. Ultimately, though the chemistry of the catalytic reduction of nitrogen oxide emissions is in most cases controlled by the conversion of NO. 

Armor, J.N. (1995) Catalytic reduction of nitrogen oxides with methane in the presence of excess oxygen A review, Catal. Today, 26, 147. 

Matsumoto, S. (2000) Catalytic Reduction of Nitrogen Oxides in Automotive Exhaust Containing Excess Oxygen by NOx Storage-Reduction Catalyst, Cat. Tech., 4, 102. 

Wichterlova, B., Sazama, P., Breen, J.P. et al. (2005) An in situ UV-vis and FTIR spectroscopy study of the effect of H2 and CO during the selective catalytic reduction of nitrogen oxides over a silver alumina catalyst, J. Catal. 235, 195. 

Martin, J.A., Yates, M., Avila, P. et al. (2007) Nitrous oxide formation in low temperature selective catalytic reduction of nitrogen oxides with V205/Ti02 catalysts, Appl. Catal. B... 

Broer, S. and Hammer, T. (2000) Selective catalytic reduction of nitrogen oxides by combining a non-thermal plasma and a V205-W03/Ti02 catalyst, Appl. Catal. B Env. 28, 101-11. 

Demidouk, V., Ravi, V., Chae, J.-O. et al. (2005) Pt-Al203 catalyst and discharge plasma pre-treatment techniques for enhancing selective catalytic reduction of nitrogen oxides A comparative study, React. Kinet. Catal. Lett. 85, 239-44. 

Yokoyama, C. and Misono, M. Catalytic reduction of nitrogen oxides by propene in the presence of oxygen over cerium ion-exchanged zeolites II. Mechanistic study of roles of oxygen and doped metals. J. Catal, 1994, Volume 150,9-17. 

Misono M. Catalytic reduction of nitrogen oxides by bifunctional catalysts. Cattech 1998 2 53-69. 

The operability and reliability of processes using ammonia must also be studied. With the potential for increased ammonia use in these systems (in the selective catalytic reduction of nitrogen oxides and as an absorbent), research documenting ammonia emissions and the effects of ammonia on process equipment should be conducted. Furthermore, additional investigations should be performed to determine whether ammonium salts are formed and to document their effects on both the environment and the flue gas treatment system. 

S. Y. Chung, MS Thesis, Selective Catalytic Reduction of Nitrogen Oxides by Hydrocarbons over Dealuminated Zeolite Catalysts, Pohang University of Science and Technology, 1997. 

H. Bosch and F. Janssen, Catalytic reduction of nitrogen oxides. A review of the fundamentals and technology, Catal. Today 2 369 (1988). 

S. Matsuda, T. Kamo, A. Kato, F. Nakajima, Deposition of ammonium bisulfate in the selective catalytic reduction of nitrogen oxides with ammonia, Ind, Eng, Chem. Prod, Res, Develop, 2I A% (1982). 

M Kotter, H G Lintz, T. Turek, Selective catalytic reduction of nitrogen oxide by use of the Lijungstroem air-heater as reactor A case study, Chem. Eng. Sci. 47 2763 (1992). 

Kotter M., Lintz H.-G. and Turek T., Selective catalytic reduction of nitrogen oxide by use of the Ljungstroe air heater as reactor A case study, Chem. Eng. Sci. 47 (9/11) 2763 (1992). Lintz H.-G. and Turek T, The selective catalytic reduction of nitrogen oxides with ammonia in a catalytically active LJungstroem heat exchanger, in New Frontiers in Catalysis, Guezi et al., eds, Elsevier. Amsterdam (1993). 

Zirconium dioxide and zeolites of pentasil structure are widely used as catalysts and efficient carriers in many heterogeneous reactions, and particularly in the process of selective catalytic reduction of nitrogen oxides by hydrocarbons (SCR-process) [1,2]. Synthesis of new catalytic systems for NOx SCR-process by CnHm is therefore related with searching for their optimum composition and preparation methods to attain maximum activity in this reaction. 

Preparation of vanadium-based catalysts for selective catalytic reduction of nitrogen oxides using titania supports chemically modified with organosilanes... 

Preparation of vanadium-based catalysts for selective catalytic reduction of nitrogen oxides using titania supports chemically modified with organosilanes H. Kominami, M. Itonaga, A. Shinonaga, K. Kagawa, S. Konishi and Y. Kera 1089... 

S. C. Tseng, W. Jozewicz, and C.B. Sedman, "Pilot Plant Investigation of the Technology of Selective Catalytic Reduction of Nitrogen Oxides", presented at EPA/EPRI 1991 Joint Symposium oh Stationary Combustion NOx Control, Washington, DC, March, 1991. 

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