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

PP-III-23EXPERIMENTAL INVESTIGATION OF NO YIELD VERSUSMONOLITHS GEOMETRY IN AMMONIA OXIDATION PROCESSL.A. Isupova, E.F. Sutormina, N.A. Kulikovskaya, A.A. Marchuk,V.P. Zakharov, I.A. ZolotarskiiBoreskov Institute of Catalysis SB RAS, pr. Lavrentieva, 5, Novosibirsk, Russia, 630090Ammonia oxidation process in nitric acid production (4NH 3 + 5O 2 4NO + 6H 2 O) isrealized on Pt gauzes in different plants under atmospheric, medium and high pressure. Due tohigh temperature operation conditions, Pt losses occur. At that, the last gauzes in the catalystlayer polish ammonia conversion while still lose a sound portion of noble metals. Therefore,an idea to replace them by less expensive oxide catalyst was evident. In 1960 th the two stagecatalytic system (1 gauze + layer of palletized oxide catalyst) was developed by GIAP fornormal pressure plants [1]. In 1990 th BIC-42-1 honeycomb catalysts was developed atBoreskov Institute of Catalysis for UKL-7 high pressure plant [2, 3]. It is shaped as a70x70x50 mm monolith with square cannels (5x5 mm) and wall thickness 1.8-2.2 mm. Itsapplication (9 gauzes and 1 layer) results in 25-30% saving in gauzes loading and 15-20%reduction of Pt losses at near the same product yield and longer gauzes life time [4].Honeycomb catalyst seems to be more attractive providing uniformity of gas flow, lowpressure drop and low dust formation.Mathematical modelling of a two-stage catalytic system for medium pressure plant AK-72 (operation pressure – 3.5 Bar) was performed as well [5]. This reactor is normally loadedby 7 woven Pt gauzes with an initial fibre diameter of 0.092 mm. The mathematical modelapplied presumes mass transfer limitation of the reaction both on Pt gauzes and a honeycombcatalyst. It was calculated that system consisting of 4 Pt gauzes and 1 layer of honeycombswith 50 mm height and not less than 50 cpsi should provided ammonia conversion as for 7woven Pt gauzes [5]. Strong requirement to catalyst for application in AK-72 is its highselectivity. It is also known that catalyst geometry may influence not only on the ammoniaconversion, but also on the NO yield due to possibility of different secondary reactions.The main goal of this investigation is experimental investigation of NO yield forhoneycomb monoliths of different chemical composition and geometry for application atmedium pressure plant. For such investigation the lab-size monoliths with 2 types ofgeometry (Table 1) were prepared using modified frame structured cordierite-like materials,perovskite-like oxides and iron oxide.346