Markus Klöker

Investigation of different column configurations for the ethyl acetate synthesis via reactive distillation

Abstract The ethyl acetate synthesis via reactive distillation is studied theoretically and experimentally using different catalytic packings. Experiments are carried out at laboratory scale in a 50 mm diameter column with a packing height of 3 m, and at semi-industrial scale in a 162 mm diameter column with a packing height of 12 m. The experimental set-up is similar for both cases. The commercially available packings studied are KATAPAK®-S and two different variants of MULTIPAK®. Modelling is performed with a rate-based stage model. The simulation environment ASPEN Custom Modeler™ is used for the implementation and solution of the model equations. The results of the rate-based simulations agree well with the corresponding experimental results. In addition, suitable operating conditions and the influence of the selected catalytic internal on conversion and product purity are investigated. The developed model enables the scale-up from laboratory to industrial size columns, based on the respective packing characteristics.

On the development of new column internals for reactive separations via integration of CFD and process simulation

Reactive separations combining mass transfer with simultaneous chemical reactions impose additional requirements on the applied column internals. Traditionally, reactive separation processes have been optimised via operational parameter adjustment. By this way, a direct influence of the internals geometry and structure cannot be taken into consideration. Therefore, the application of process-specific column internals, rather than of the internals currently available on the market, is desirable. Development of new internals is a major focus of interest in an European project entitled Intelligent Column Internals for Reactive Separations. In particular, such development is achieved by the application of modern CFD facilities combined with the rigorous, rate-based process simulation. An important challenge is to provide an opportunity of obtaining hydrodynamic and mass-transfer correlations, necessary for the process description, not only from the experimental measurements, but also directly from the CFD simulations. In this paper, a way to generate virtual correlations is demonstrated for a single-phase flow through structured packings. The rate-based simulation is illustrated with the heterogeneously catalysed synthesis of n-hexyl acetate via reactive distillation.

Catalytic Distillation for TAME Synthesis with Structured Catalytic Packings

The paper describes reactive distillation modelling and parameter determination and it presents a model validation with pilot plant experiments. TAME, one of the main ether fuel additives is chosen as a test system. Pilot plant tests were carried out in a 200 mm inside diameter (I.D.) column equipped with a pre-reactor, a reactive section (Multipak ® , type 1 and 2), and stripping and rectifying sections (Bialecki rings). Experimentally determined characteristics of Multipak ® include hold-up, pressure drop, gas and liquid mass transfer coefficients (air–water, 250 mm I.D. column). A rate-based model of the reactive distillation column was developed. Validation based on pilot plant tests proved that the model accuracy is satisfactory. Simulations performed with the validated software revealed the influence of reflux ratio (RR), distillate-to-feed (D/F) ratio, feed composition and packing height on the process conversion and selectivity. Two Multipak ® types were compared with two KATAPAK-S ® packing versions for different RR and D/F ratios. The significance of the pre-reactor was examined.

Experimental and theoretical studies of the TAME synthesis by reactive distillation

The heterogeneously catalysed synthesis of TAME (tert-amyl-methyl ether) via reactive distillation is investigated experimentally and theoretically. The structured catalytic packing Montz MULTIPAK®-2 is used in the catalytic section of a 200 mm diameter pilot scale column with a total packing height of 4 meters. Simulations with a developed rate-based model covering 11 components and 4 chemical reactions are in good agreement with experimental data. The simulations studies show the influence of the reflux ratio on conversion and selectivity.