The production of Dimethyl Ether by catalytic distillation: a combined modeling and experimental approach
Special Symposium - EPIC-1: European Process Intensification Conference - 1
EPIC-1: Poster Session (EPIC - Poster) - P2
Keywords: DME, process intensification, reactive distillation, rate-based approach, Katapak-SP
This paper regards the field of the chemical engineering that is commonly identified as Process Intensification (PI). The main objective of PI is to improve processes and products to obtain technologies more safe and more economic.
The European Project entitled “INtegrating SEparation and Reactive Technologies” (INSERT) involves Eni SpA and the University of Pisa, together with others European Universities and Research Groups, with the aim of providing a general methodology for a systematic development of multifunctional reactors. It has been chosen to apply Catalytic Distillation, the most promising application of the intensification principles to the production of dimethyl ether (DME) from methanol. In recent years, DME is gaining attention as a promising alternative clean fuel, thanks to its low toxic index and the versatility of its use. Its production starting from methanol represents one of the routes for technological innovation in natural gas valorisation. Besides the industrial production advantages, the catalytic distillation synthesis of DME has some peculiarities particularly useful for the validation of the INSERT methodology. In fact, the conventional process is well known in literature and a direct comparison between the industrial configuration and the innovative reactive distillation approach can be directly done. Moreover, at the selected operative conditions, no side reactions is expected and the only side product is water.
The study covers both the theoretical aspects to develop mechanistic models and an extensive experimental programme. The latter is useful to provide the necessary parameters and scale up knowledge and to validate the models developed and the INSERT methodology.
A pilot plant consisting of a pre-reactor and a distillation column has been built up to investigate experimentally the rate of integration between the separation and the reaction in a continuous process behaviour. The pilot plant can work in two different configurations. In the first one the reaction takes place inside the pre-reactor while the column works as a common distillation column. In the second configuration, the reactor is bypassed while the column works as a reactive distillation column. The pre-reactor is a fixed bed of 50 mm internal diameter and 2 m height. The column has an internal diameter of 50 mm, is equipped with an internal reboiler and has an effective packing height of 4 m comprising four sections of 1 m each. The rectifying zone at the top and the stripping zone at the bottom are filled with Sulzer BX packing while the two middle sections can be equipped with either the BX packing or the Sulzer Katapak-SP11 reactive packing, according to the working configuration. The catalyst used for the pre-reactor and the reactive packing is the commercial sulfonic resin Amberlyst 35 wet (by Rohm and Haas). The catalytic distillation column has been simulated using a rate-based approach, while for the pre-reactor a simpler model has been used, limited to a “single-phase” reactor (liquid phase). The developed models have been implemented into the simulation environment Aspen Custom Modeler.
A first experimental campaign has been carried out, and despite to the fact that no parameters have been adjusted the model results have shown a good agreement with experimetal data. The experimentation is running nowadays and the complete set of results will be soon available for the final model validation and scale up criteria implementation.
Acknowledgement
We acknowledge the financial support provided by the European Commission within the 6th Framework Programme, Project “INSERT – Integrating Separation and Reaction Technologies”; Contract-No: NMP2-CT-2003-505862
Presented Thursday 20, 13:30 to 14:40, in session EPIC-1: Poster Session (EPIC - Poster) - P2.
