CORDIERITE-LIKE MIXED OXIDE MONOLITH FOR AMMONIA OXIDATION
PROCESS
L. A. Isupova, E.F. Sutormina,
Boreskov Institute of Catalysis SB RAS, pr. Lavrentieva, 5, Novosibirsk, Russia, 630090
isupova@catalysis.ru
Ammonia oxidation process in nitric acid production (4NH3 + 5O2 4NO + 6H2O) is
realized on Pt gauzes at high temperatures in different plants under atmospheric, medium and
high pressure. To decrease Pt loses the two stages catalytic system (1 gauze + layer of
palletized oxide catalyst) was developed by GIAP (in 1960th) for normal pressure plants [1].
For high pressure plant honeycomb catalyst seems to be more attractive providing uniformity
of gas flow, low pressure drop and low dust formation. In 1990th BIC-42-1 honeycomb
catalysts was developed at Boreskov Institute of Catalysis for UKL-7 high pressure plant [2].
It is shaped as a 70x70x50 mm monolith with square cannels (5x5 mm) and wall thickness
1.8-2.2 mm. Its application (9 gauzes and 1 layer) results in 15-20% reduction of Pt losses at
near the same product yield and longer gauzes life time [3].
For future decrease of Pt loading and losses the monolith with higher cannel density
are required. Mathematical modelling of a two-stage catalytic systems for UKL-7 plant
(mathematical model applied presumes mass transfer limitation of the reaction both on Pt
gauzes and a honeycomb catalyst) revealed that system consisting of 8 Pt gauzes and 1 layer
of honeycombs with 50 mm height and ~150 cpsi should provided ammonia conversion as for
12 woven Pt gauzes [4]. Strong requirement to catalyst is its high selectivity (~90%) to NO.
The cordierite-like materials is characterized by a low thermal expansion coefficient
that is very important for catalyst stability. Good rheological properties of raw materials give
the possibility to prepare monolith with high channel density. Modification of material with
the most active in ammonia oxidation oxides (Mn, Co, Fe, V, Bi)Ox looks very promising for
preparation of honeycomb monoliths for ammonia oxidation process. This paper deals with
preparation and characterization of modified cordierite-like monolith as catalysts for ammonia
oxidation.
As a result NO yield for monoliths with ~150 cpsi was shown to depend on the testing
temperature, nature and content of active oxides, and crystalline degree of cordierite. The best
data (NO yield ~ 90%) at 880-900 oC were obtained for iron and cobalt based modified
monolith.
1. M.M. Karavaev, A.P. Zasorin, N.F. Klesev. Catalytic oxidation of ammonia. Moskow, Khimiya, 1983.232
c.(In Russian); 2. V.A. Sadykov, L.A. Isupova, I.A. Zolotarskii et al. Applied Catalysis A: General 204 (2000)
59.; 3. V.I. Chernyshev, E.A. Brushtein, Catalysis in Industry, 3 (2001) 30 (in Russian); 4. L. A. Isupova, I.A.
Zolotarskii, N.A. Kulikovskaya, et al. In: Chem. Reactor-17, Athens, 2006.
The main goal of this investigation is experimental investigation of NO yield for
honeycomb monoliths of different chemical composition for application at medium pressure
plant. For such investigation the lab-size monoliths with 2 types of geometry (Table 1) were
prepared using modified frame structured cordierite-like materials, perovskite-like oxides and
iron oxide.
Ammonia oxidation process was carried out in a bench scale quartz tubular reactor
with inner diameter of 26 mm at temperature 700-900 oC and atmospheric pressure. Samples
of honeycomb catalysts in the form of fragments with diameter of 21-22 mm and length of 50
mm were tested with and without one Pt sheet. Before the reaction starts up, catalysts were
preheated at 700 oC in air for 30 minutes. Then reaction gazes (5% ammonia in the air
preheated at 450oC in a quartz mixer) were flowed through the catalyst with 7.6 l/min flow
rate (standard gas velocity 0.33 m/s). The ignition of the catalyst was determined by
temperature increase. Ammonia, NO and NO2 concentrations were analyzed by the on-line
spectrophotometer analysis [6, 7].
Table 1. Honeycombs geometry
Channels
d,
form
mm
1 triangular 2.5
2 triangular 4.0
D,
S,
N
,

mm mm m2/m3 cpsi
0.4 1.53 1520 180 0.63
1.2 2.27 890
56 0.41
All as prepared catalysts provide 100 % ammonia conversion degree even without Pt
gauzes at temperature higher 850 oC 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 depend
on the temperature and chemical composition of monoliths (with the same geometry) as well
as on the channel density [3]. Monoliths with 56 cpsi have revealed the NO yield not higher
than 86% at 900 oC most probably due to the influence the homogeneous reactions. NO yield
increases with increase of channel density only for Fe2O3-based catalysts and for BIC-42-1
honeycombs with 180 cpi nearly 90% NO yield was revealed. The best data (NO yield higher
95%) at 830-900 oC were obtained for modified BIC-42-1 iron oxide-based monolith with 180
cpsi.
REFERENCES
1. 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. Malta
7.
8.
L. A. Isupova, E.F. Sutormina, N.A. Kulikovskaya, et al. Catalysis.Today105(2005) 436.
Е. F. Sutormina, J. Analytic Chem.59/4 (2004) 1 (In Russian).