A New Production Technology Of Nitric Acid
A NEW PRODUCTION TECHNOLOGY OF NITRIC ACID
IN NON-PLATINUM CATALYST AEROSOULE
A.I. Volga, M.A. Glikin, D.A. Kutакоvа, E.M. Prin, L.S. Lahmanchuk
State Research and Design Institute of Chemical Technology "Khimtekhnology",
Vilesov st. 1, 93400 Severodonetsk, Lugansk region, Ukraine
fax: (06452) 25367, e-mail: vera@ixt.lg.ua
The increasing attention has recently been given to mechanoactivation in catalyst production. The influence of mechanical treatment on catalytic system activity is caused both by growth of active center concentration on a catalyst surface, due to structure defect formation, and by dispersion. Catalytic system nanoparticles being formed have the large amount of surface atoms, which determine unique properties of powders, besides with own size of nanoparticles comparable with sizes of molecules. All this determines kinetic distinction of chemical processes on a surface of ultradispersion catalytic system.
Under these conditions we investigated the process of ammonia oxidation by atmospheric oxygen for nitric acid production. The choice of process was dictated by urgency of the problem of nitrogen compounds production and search of technologies that exclude platinum usage. At the given stage the researches were carried out on the catalytic system α-Fe2O3. The choice of this oxide was not occasional. Analysis of the literature carried out has shown that most promising oxides in this process are Co3O4, Cr2O3 and Fe2O3, which have served as objects for many researches Tab. 1. [1]. However, the most available and cheap among them is iron oxide (ІІІ) Fe2O3.
Table 1. The optimum temperature conditions of ammonia oxidation
Oxide
Т, оС
Yield, %
Oxide
Т, оС
Yield, %
Co3O4
650
97,5
NiO
825
64,5
Cr2O3
850
92,0
CuO
700
49,0
Fe2O3
750
89,0
V2O5
300
15,0
Mn2O3
730
78,0
ZnO
750
11,0
(Ammonia concentration - 10 % vol., linear rate of gas - 0,2-0,8 м/с, contact time -2 × 10-3- 6 × 10-2 sec.)
The obtained experimental data have shown an abrupt growth of catalytic system activity and selectivity during transition from the classic catalyst to aerosol of active substance without the carrier. The selectivity of ammonia conversion to nitrogen oxides (NO and NO2) was at range 98-99 %.
The researches of the α-Fe2O3 aerosol particle range were carried out by transmission electronic microscopy (TEM), electron diffraction (EDI) and electronic spectroscopy with energy absorption (EELS). Typical radius of the investigated aerosol particles is 100nm. Also we found out the accompanying particles that have the range 10nm and less; and they are adsorbed by larger particles fig. 1. The investigated samples cannot characterize distribution of particle ranges inside reactor. However, they have confirmed our assumption on the presence of particle with ranges about the nanometer in reaction zone. These researches were carried out by Dr. Тhomas Каuffeldt, Institute of Burning and Gasodynamic, University of Duysburg, Germany.
Fig. 1. The ТEМ measurement of particle size
Thus we have proved the principal possibility of mechanoactivation in situ.
References
1. Kleshev N.Ph., Atroshenko V.I. K. Catalysis and catalysts., 1976, p.3-5.
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