(74d) Chemical Reaction with Extraction - Investigation of Catalysts for Synthesis of Methyl Acetate

Processes which combine reaction and product separation in one step are of rising interest in the chemical industry as well as petrochemical and pharmaceutical industry. These reactive systems are well known as hybrid processes. Main application of hybrid processes is reactive distillation, a combination of equilibrium reactions and product separation by distillation.

The hybrid process of reactive distillation can be applied for separating products with different boiling point from equilibrium mixtures. Conversion increases by removing the product. The same effect can be achieved by combining chemical reaction with extraction. Provided that an appropriate solvent can be found which dissolves the product with sufficient selectivity the result of extractive separation of products from reaction mixtures is comparable with distillative product separation except that chemical reaction with extraction can be operated at ambient temperature. As a consequence lower cost of operation and less complexity of control systems is expected.

In this project the synthesis and isolation of methyl acetate by chemical reaction with liquid/liquid extraction has been investigated. Methyl acetate synthesis has been chosen because of the difficult to separate multi component product mixture of methyl acetate?methanol?water?acetic acid. On the other hand industrial production of methyl acetate is based on a well established hybrid process (Eastman Kodak process), a well reported basis for technical and economical process comparison.

Esterification of acetic acid with methanol is accelerated with several homogenous and heterogeneous catalysts. For extractive separation of methyl acetate from the reaction mixture with hydrocarbons (C8 to C10) the solvent and the catalyst must not undergo any disadvantageous mutual interaction.

Main focus of this work was to test heterogeneous catalysts like Lewatit (ion-exchangers) and homogenous catalysts like sulphuric acid. Experimental series included variation of temperature, concentration and separation of products by liquid/liquid extraction.