(58l) A Smart Computing-Based Protocol for Analysis of Certain Classes of Complex Chemical Reactions

Complex reactions - combinations of multiple consecutive-competitive reactions – are encountered in a variety of chemical transformation processes, some examples being halogenation, hydrogenation, and oxidation reactions, polymerization reactions, and degradation of polymers. A large number of these reactions are encountered in living systems (cell cultures) and are responsible for formation of classes of biopolymers, such as polysaccharides, polypeptides, informational biopolymers (DNA, RNA), lipids, and hybrids of these. The largest source of organic matter on this planet, cellulose and starch, are repetitive polymers of glucose. Formation of cellulose and starch (molecular weight running into few millions) from glucose (molecular weight – 180) involves a very large number of condensation reactions and conversely, formation of glucose from cellulose and starch involves a very large number of hydrolysis reactions. Many of the complex reaction schemes are competitive or parallel with respect to a primary reactant and consecutive or series with respect to intermediates. Dependence of the rates of the individual reactions on concentrations of two reactants for that reaction, the common primary reactant and another primary reactant or an intermediate, leads to a large number of nonlinear conservation equations for the species participating in the complex reaction schemes, requiring tedious numerical analysis for prediction of reactor performance and design of the reactors. A far more efficient protocol is presented here for analysis and design of reactors for conducting certain classes of complex reactions. The solution to the multi-reaction and multi-species problem is made easier by (i) identifying stoichiometric hyperplanes among attributes (concentrations, moles, fluxes) of species participating in a complex reaction scheme based on characteristics of the stoichiometric matrix associated with the reaction scheme, (ii) working with appropriate pairs of conservation equations, and (iii) obtaining binary relations among concentrations of some of the species participating in the complex reaction scheme. These binary relations among species concentrations are obtained analytically. While completely analytical solutions to reactor design problem are not possible, the required numerical effort is reduced drastically because of the analytical identification of binary relations among concentrations of some species. The advantages of this protocol are illustrated with suitable examples of complex reaction schemes considering the popular workhorses used in industry for conducting complex reactions, namely the batch reactor, the continuous flow well-mixed reactor, and the continuous flow unmixed reactor (plug flow reactor and packed bed reactor). Analysis and design of reactors for conducting complex reactions is made very precise by this largely analytical approach. The characteristics of the complex reaction schemes, such as maxima in concentrations of intermediates and conditions under which they are attained, can be evaluated and studied conveniently using the largely analytical protocol developed here.