Oscillatory chemical reaction as model system for the catalysts characterization

Abstract

The main kinetic characteristics of a catalyst could be obtained by examination of its behavior in some known reaction system, so-called model reaction system. The model reaction system is usually chosen to be as simple as possible. Therefore, for this purpose, the first or second order reaction with relatively simple mechanism and with only one reaction pathway is often selected. However, for the model reaction system one oscillatory chemical reaction, having the complex mechanism with the alternating reaction pathways, could be chosen. It can be expressed over the state far from equilibrium and the variety of kinetic characteristics, resulting from the properties of examined catalyst, can be found. The special attention is paid on Bray-Liebhafsky oscillatory chemical reaction, as well as on the comparative analysis of the iron based catalysts, whereby iron could be used either as peroxydazirene or supported on acidic polyvinylpyridine. .

Glavne kinetičke karakteristike katalizatora dobijaju se ispitivanjem njegovog ponašanja u nekom poznatom reakcionom sistemu, takozvanom modelnom reakcionom sistemu. Za modelni reakcioni sistem obično se bira što je moguće jednostavniji. Zbog toga se, u tu svrhu, najčešće koristi neka reakcija prvog ili drugog reda sa definisanim i jednostavnim mehanizmom i jasnom stehiometrijom ukupne reakcije, kao i samo jednim reakcionim putem. Međutim, za modelnu reakciju može se izabrati i neka složena hemijska reakcija, na primer, neka od oscilatornih hemijskih reakcija sa nizom alternativnih reakcionih puteva, a koji se ispoljavaju u nekim od njenih stanja daleko od ravnoteže. Kao takva, veoma je osetljiva na uvođenje katalizatora čija svojstva želimo ispitati. Ovom prilikom pažnja je posvećena modelnoj Bray-Liebhafsky (BL) oscilatornoj reakciji i uporednoj analizi katalizatora na bazi gvožda bilo da je u pitanju gvožđe u peroksidazi rena ili ono naneto na kiseli polivinilpiridin. .