INFLUENCE OF ADDITIONAL SLOW STAGES ON KINETIC REGULARITIES OF CHEMICAL REACTIONS

Abstract

It is known that mechanisms with a different set of elementary stages are alternatively used to describethe kinetic patterns of chemical reactions involving the same reagents. In this regard, the article introduces two concepts–the "initial" reaction mechanism, which is obtained as a result N.I. Kol’tsovChemChemTech. 2022. V. 65. N 833of experimental studies, and alternative reaction mechanisms thatcan demonstrate dynamic be-havior close to the original mechanism. Alternative mechanisms include all stages of the original mechanism and additional slow stages satisfying certain stoichiometric constraints. The influence of additional dependent and independent slow stages on the patterns of chemical reactions in closed and open reactors of ideal mixing is investigated. It is established that the introduction of slow linearly dependent stages into the reaction mechanism does not significantly affect its kinetic pat-terns. The addition of the reaction mechanism by slow linearly independent stages leads to a change in its dynamics, which does not allow them to be used as part of alternative mechanisms. The article describes an approach that allows us to detectdependent stages, check the possibility of their im-plementation by comparing stationary and non-stationary characteristics (coordinates of stationary states, linear and nonlinear relaxation times, etc.), analyzing the properties of the matrix of stoi-chiometric coefficients (the number of rows and columns) and its rank (the maximum number of independent rows or columns). In this case, the main role is played by stoichiometric conservation laws (stationary and non-stationary), taking into account the peculiarities of their implementation in closed, quasi-open and fully open reactors of ideal mixing. Examples are given demonstrating the influence of additional dependent and independent slow stages on the dynamics of reactions. The results obtained can be useful in practice when solving inverse problems of chemical kinetics to clarify the mechanisms of specific complex reactions.