Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

PP-III-23Ammonia oxidation process was carried out in a bench scale quartz tubular reactor withinner diameter of 26 mm at temperature 700-900 °C and atmospheric pressure. Samples ofhoneycomb catalysts in the form of fragments with diameter of 21-22 mm and length of 50mm were tested with and without one Pt sheet. Before the reaction starts up, catalysts werepreheated at 700 °C in air for 30 minutes. Then reaction gazes (5% ammonia in the airpreheated at 450 °C in a quartz mixer) were flowed through the catalyst with 7.6 l/min flowrate (standard gas velocity 0.33 m/s). The ignition of the catalyst was determined bytemperature increase. Ammonia, NO and NO 2 concentrations were analyzed by the on-linespectrophotometer analysis [6, 7].ChannelsformTable 1. Honeycombs geometryd,mmδ,mmD,mmS,m 2 /m 3Ncpsi1 triangular 2.5 0.4 1.53 1520 180 0.632 triangular 4.0 1.2 2.27 890 56 0.41εAll as prepared catalysts provide 100 % ammonia conversion degree even without Ptgauzes at temperature higher 850 °C that is in agreement with our calculations for lab reactor.NO yield for monoliths and in the two-stage system (with one Pt gauze) was shown to dependon the temperature and chemical composition of monoliths (with the same geometry) as wellas on the channel density [3]. Monoliths with 56 cpsi have revealed the NO yield not higherthan 86% at 900 °C most probably due to the influence the homogeneous reactions. NO yieldincreases with increase of channel density only for Fe 2 O 3 -based catalysts and for BIC-42-1honeycombs with 180 cpi nearly 90% NO yield was revealed. The best data (NO yield higher95%) at 830-900 °C were obtained for modified BIC-42-1 iron oxide-based monolith with180 cpsi.References1. M.M. Karavaev, A.P. Zasorin, N.F. Klesev. Catalytic oxidation of ammonia. Moskow, Khimiya, 1983.232 c.(In Russian).2. V.A. Sadykov, E.A. Brushtein, L.A. Isupova, et al. Chemical Industry, No 12 (1997) 33 (In Russian).3. V.A. Sadykov, L.A. Isupova, I.A. Zolotarskii et al. Applied Catalysis A: General 204 (2000) 59.4. V.I. Chernyshev, E.A. Brushtein, Catalysis in Industry, 3 (2001) 30 (in Russian).5. L.A. Isupova, I.A. Zolotarskii, N.A. Kulikovskaya, et al. In: Chem. Reactor-17, Athens, 2006.6. L.A. Isupova, E.F. Sutormina, N.A. Kulikovskaya, et al. Catalysis.Today105(2005) 436.7. Е.F. Sutormina, J. Analytic Chem.59/4 (2004) 1 (In Russian).347