Equilibrium controlled reactions

For equilibrium-controlled reactions, the probability of formation of the ineffective cycles depends on their thermodynamic stability. The fraction of such cycles on the stage of polymer formation can be only estimated if we know the relative constant of... 

The kinetics of this equilibrium-controlled reaction have been worked out in detail (Oyama, 1981a,b). From all the possible ways to shift the equilibrium in favor of synthesis of dipeptide ... 

Table 2.11 Heuristics for chemical-equilibrium-controlled reactions.

Amylose was also prepared via in vitro polymerization of D-glucosyl phosphate catalyzed by a potato phosphorylase (120). A large excess amount of Glc-l-P is required in this equilibrium-controlled reaction. 

The concept that the removal of an undesired reaction product by selective adsorption from the reaction zone of an equilibrium-controlled reaction increases the conversion and the rate of formation of the desired component (based on Le Chatelier s principle) was used to develop a novel PSA process concept called SERP for direct production of fuel cell-grade hydrogen by steam reforming of methane (CH4 + 2H20 44 C02 + 4H2).57 61 The concept uses a physical admixture of a reforming (noble metal on alumina) catalyst and a chemisorbent (K2C03 promoted hydrotalcite), which selectively and reversibly chemisorbs C02 from a gas at a temperature of -450 °C in the presence of steam. The cyclic SERP steps consisted of the following ... 

An important crosscheck is the media restriction. Paths that form reactive cations almost exclusively occur in acidic media. Likewise, paths that form reactive anions are the domain of basic media. No medium can be both a strong acid and a strong base it would neutralize itself. The reactive species in equilibrium-controlled reactions have a limited range of acidities. For example, in neutral water the hydronium ion concentration and the hydroxide ion concentration are both 10 mol/L. Their relative concentrations are defined by = [H ][OH ] = Their p Ta values span 17.4 p fa... 

In the case of a multistep reaction, the measured jEX may not be an activation energy of an elementary reaction. For example, if in a two-step reaction the rate-determining step is preceded by a rapid equilibrium-controlled reaction, the AH of the first reaction contributes to the measured activation energy (Stumm and Morgan, 1981). The activation energy determined by the temperature dependence of the reaction is then only an apparent activation energy. 

Shift the maximum conversion for equilibrium controlled reactions. 

This is an example of a rate-controlled vs, equilibrium-controlled reaction. If the rate controlled product is reversible, and sufficient time is allowed for the equilibrium-controlled reaction to occur, the more stable product will be the result. 

This new set of variables defines a sub-region of lower dimension in the composition space composed of the feasible product compositions for equilibrium controlled reactions. The RCM problem is solved by specifying the refation between the transformed... 

Nataraj, S. et al., Process for operating equilibrium controlled reactions, Canadian Patent 2,235,928 (1998). 

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