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Mathematical modeling and optimization of N2O decomposition catalyst

L. Obalová

VSB-Technical University of Ostrava, Institute of Environmental Technology and Faculty of Metallurgy and Materials Engineering, 17. listopadu 15, 708 33 Ostrava, Czech Republic, Tel.: +420 597 321 532, E-mail: lucie.obalova@vsb.cz


Multicomponent mixed oxides prepared by thermal treatment of layered double hydroxide (LDH) precursors seem to be promising catalysts for this reaction. Layered double hydroxides with general chemical composition of [MII1-xMIIIx(OH)2]x+[An-x/n.yH2O]x- where MII and MIII are divalent and trivalent metal cations and An- is an n-valent anion (often carbonate) consist of positively charged hydroxide layers separated by interlayers containing anions and water molecules. Thermal treatment of LDH precursors gives finely dispersed mixed oxides of MII and MIII with large surface area, good thermal stability and high activity for N2O catalytic decomposition.
Intrinsic kinetic data were obtained in laboratory experiments of N2O decomposition over grained LDH-related mixed oxides; these data were used for modeling of catalytic performance of catalyst particles suitable for industrial use and compared with experiment. Pseudo-homogeneous one-dimensional model of an ideal plug flow reactor in isothermal regime was applied; the effect of internal and external mass transport was described by effectiveness factor. The N2O abatement by using a catalytic reactor situated downstream the DeNOx technology in nitric acid production unit was estimated, based on laboratory data of N2O decomposition in simulated off gas from nitric acid production.