Introduction

The ion exchange polymers most often used in catalysis are insoluble materials that can be constructed from inorganic or organic monomer units. This article will present only catalysis performed by the organic ion exchangers that are insoluble solids. There are commercial ion exchangers that are liquids, but to date they have been used very little in catalysis and, therefore, will not be included in this discussion.

Insoluble ion exchangers carry out their catalytic work in a heterogeneous rather than a homogeneous fashion and are, therefore, part of the group called heterogeneous catalysts. Heterogeneous catalysts have three very significant advantages over homogeneous catalysts: first, they are not corrosive; second, they are very readily separated from the reaction mixture by a simple filtration; and third, they are most often recyclable from one run to the next without any added treatment. Potentially, they suffer one major disadvantage over homogeneous catalysts. Intimate contact between reactants and the catalytic site is not achieved simply by mixing the heterogeneous catalyst with the reactants. In a stirred reactor, intimate contact between reactants and the homogeneous catalyst is very easily achieved and mass transport of reactants to catalyst is very rapid and almost never rate-limiting. With heterogeneous catalysis, mass transport of reactants to the catalytic site may often be the rate-limiting element, especially if the activation energy for the reaction is small and the chemical reaction is rapid. There are excellent texts and monographs on the issues surrounding heterogeneous catalysis, and the reader is referred to these for the development of a fuller understanding (see Further Reading).

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

Get My Free Ebook


Post a comment