Chemical Kinetics and Microheterogeneous Catalysis

Chapter 1

Juan C. Mejuto

Abstract

1. Introduction

3

2. The pseudophase model

occur simultaneously (see Figure 1).

Pseudophase Model in

the literature in a large variety of chemical reactions.

Antonio Cid, Aangel Acuña, Manuel Alonso-Ferrer,

Gonzalo Astray, Luis García-Río, Jesus Simal-Gándara and

The kinetic behaviours in microemulsions can be easily modelled using an extension of the pseudophase model previously developed for micellar catalysis. This model considers that the microheterogeneous media can be considered as the sum of different conventional reaction media, where the reagents are distributed and in which the reaction can occur simultaneously. The reaction rate observed in the microheterogeneous system will be the sum of the velocities in each one of the pseudophases. This use can be considered as an extension of the pseudophase model, which has been developed for the quantitative analysis of nitrosation reactions in AOT/isooctane/water microemulsions and has been applied successfully in

Keywords: microemulsions, reverse micelles, kinetic model, pseudophase model

The use of microemulsions, in particular, colloidal self-aggregates, and in general, as reaction media [1] makes the application of kinetic models necessary for the quantitative interpretation of the observed results. In this sense, a simple thermodynamic model was developed for its application in micelles [2] and it was called the pseudophase model [3]. This model was successfully applied through extensions

This model considers that the micellar system can be considered as the sum of two conventional reaction media, the continuous pseudophase and the micellar pseudophase, where the reagents are distributed and in which the reaction can

In this figure, A and B are the reagents, k is the kinetic constant and the subscripts w and m denotes the reaction loci (w corresponds to the continuous pseudophase and m is the micellar pseudophase). Finally, KA and KB are the distribution coefficients of both reactants between different pseudophases.

to different microheterogeneous systems over the last 50 years [4–10].

Microemulsions
