Catalytic processes for esterification of carboxylic acids

Abstract

An improved process for the esterification of carboxylic acid and alcohols into carboxylic ester is disclosed. It comprises the steps of: (a) charging the esterification reactants into a fixed bed reactor under a predetermined reaction condition; and (b) reacting the esterification reactants in the fixed bed reactor. The fixed bed reactor contains acidic catalysts that are present in a solid phase, and the reaction condition is controlled such that (i) the reactants and the products co-exist in a gas-liquid two-phase equilibrium in the fixed bed reactor and that (ii) at least one component of the reactants is present in one phase and at least one component of the products is present in another phase. Because a phase change is always taking place concurrently with the esterification reaction; the reaction stream is maintained at a relatively uniform temperature. This greatly reduces the chances of catalyst poisoning and minimizes the formation of undesired by-products such as polymers/oligmers and ethers, which are often produced at high temperatures. The concurrent phase change also contributes to the extremely high reaction yield and selectivity, typically better than 90%, observed in the present invention.