Colloquium Series SS 2018 by the Department of Chemical and Biological Engineering
Developing and realizing sustainable concepts for the future of mobility is presently one of the most urgent tasks. There will be no simple one-cap-fits-all solution for the challenges in this field. Different options will have to be explored and combined suitably. Synthetic fuels play an important role in this. In Germany, much of the current discussion in this field is focused on the NOx and soot emissions of diesel engines. Synthetic fuels can contribute to solving these problems. The most attractive synthetic fuel to replace fossil diesel is OME. Germany is presently the leader in the technology to produce OME. However, it is likely to lose that position to China, where, in contrast to Germany, large-scale plants for producing OME have recently become operative.
OME (oxymethylene dimethyl ethers) are oxygenates of the structure H3C-O-(CH2O)n-CH3. OME fuels strongly reduce the soot formation in diesel engines. As a consequence, also the NOx emissions can be strongly reduced [1,2]. All routes for the production of OME are based on synthesis gas and proceed via methanol. Hence, the raw material basis for producing OME is extremely flexible: either traditional (coal, gas) or renewable raw materials (biomass, CO2) can be used. While older routes for the production of OME involved expensive intermediates like methylal and trioxane , this work presents a novel OME process that uses aqueous solutions of formaldehyde and methanol as feedstock. The process design is extremely challen¬ging as OME of the desired chain lengths n = 3 − 5 have to be separated from reactive multicomponent mixtures which show several (reactive) azeotropes, liquid demixing and solid formation. The successful design requires combining advanced experimental techniques like NMR spectroscopy with advanced physico-chemical modeling and process simulation.
The presentation covers all sides of the topic: from the physico-chemical fundamentals, over the experimental studies and the modeling, simulation, and optimization, to the application of OME as synthetic fuel and its perspectives.