III International Conference

PP-III-36pressure at 800-900 o C. The reaction gases (5-10 % ammonia in the air preheated at 450 o C ina quartz mixer) were flowed through the catalyst with 7.6 l/min flow rate (0.33 m/s at STP).An on-line UV spectroscopic method has been used for quantitative analysis of reaction gases(NH 3 , NO and NO 2 ).The structural and textural properties of frame structured cordierite-like catalysts werestudied by XRD, SEM, and adsorption measurements.According to X-ray data, cordierite phase was revealed in catalysts after their calcinationsat 1000-1200 o C for 4 h. However, catalysts with calcinations temperature below 1100 о С donot have fully formed frame structure and contain a portion of free 3d oxides. It was foundthat Bi adding facilitates cordierite structure formation.All prepared catalysts had high activity in ammonia oxidation reaction: the conversiondegree was about 95-100 % for all samples. NO yield strongly depended on catalystschemical composition and cell density. The highest NO yield was measured to be about 80 %and it was observed for the samples with high content of active component and 180 CPSI.It was shown that increase of calcination temperature did not significantly affect oncatalytic activity, whereas, it increased durability and thermoshock resistance of themonoliths.Catalysts testing in a two-stage catalytic system at normal pressure were carried out. Thetwo-stage system (one Pt gauze + monoliths with 180 CPSI) provides 100 % conversion ofammonia and NO yield about 94 %.The stability of Fe- and Mn-doped frame structured catalyst was checked by the 3-monthslife test in the UKL-7 high pressure nitric acid plant. The catalyst has retained its mechanicaland catalytic properties.References1. V.A. Sadykov, E.A. Brushtein, L.A. Isupova, et al. ‘Khimicheskaya promyshlennost’, 12 (1997)33 (In Russian).2. L. A. Isupova, I.A. Zolotarskii, N.A. Kulikovskaya, et.al. Chemreactor 17, Athens-Crete, Greece,2006, CD.3. E.G. Avakumov, A.A. Gusev. Kordierite- advanced ceramic material. Novosibirsk, SB RAS,1999 166c537