Kampen, Jasper van (PhD)

Sorption-Enhanced Dimethyl Ether Synthesis

J. van Kampen, J. Boon, M. van Sint Annaland
Room: STW 0.56, E-mail: j.v.kampen@tue.nl; vankampen@ecn.nl

Introduction

In the development of future fuels the focus is on non-petroleum based alternative fuels and more advanced technologies to increase energy efficiency. Dimethyl ether (DME) is one of the most promising alternative fuel solutions among the various ultra clean, renewable, and low-carbon fuels under consideration worldwide. In the DME production from synthesis gas (syngas), the following equilibrium reactions are involved:

Conventional, indirect DME production (Figure 1a) is a two-step process. Intermediate methanol (1) is synthesized from syngas, subsequently followed by the dehydration of methanol to DME (3) in a separate reactor. Both steps are thermodynamically limited, resulting in limited yield, extensive separations and large recycles. In recent years a lot of attention is going to the direct production of DME in a single-step process (Figure 1b). Direct synthesis reduces the extent of necessary process steps and allows for an increased overall DME yield. In terms of efficiency, the direct DME synthesis process outperforms the indirect synthesis, yet separation and recycling remain necessary. Since the reaction is equilibrium limited, downstream separation produces recycle streams of syngas (CO and H2), CO2, and methanol. Syngas and methanol are recycled back to the DME synthesis reactor, while the CO2 is recycled in synthesis gas generation via dry or tri-reforming.

Sorption-enhanced DME synthesis (SEDMES, Figure 1c) is a novel process for the production of DME from syngas, in which water is removed in situ by the use of a solid adsorbent. The concept is based on Le Chatelier’s principle stating that reactant conversion to products in an equilibrium limited reaction is increased by selectively removing reaction products. The process has been analysed theoretically, indicating that in situ water adsorption leads to an increased DME yield and selectivity.

Objective

In this project the aim is to develop and validate a flexible direct production process for (bio-based) DME from syngas utilizing sorption enhancement by in situ removal of water. SEDMES technology will mature from fundamental research to validation in a relevant environment, where the objective is an experimental validation of a full cyclic SEDMES process for 3 kg/h DME production at ECN testing facilities. To achieve this challenging target catalysts for DME synthesis, steam adsorbents and their interactions in a sorption-enhanced process will be investigated under industrially relevant conditions. Isotherm and reaction models are developed and a cyclic design is made for the  SEDMES process. This will result in performance analysis and predictions of large scale DME reactors. The overall DME production process is studied, optimized and an efficiency comparison will be made.

This ECN project in collaboration with TU/e has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 727600.