Strategies for developing renewable high-performance carbon fibres
The demand for carbon fibres in aircraft development is expected to grow. However, state-of-the-art production of this innovative material via the key compound acrylonitrile is still based on fossil resources.
In this context, synthesis via acrylonitrile from renewable resources represents a promising perspective: It combines novel synthetic routes towards acrylonitrile with the established production of carbon fibres, thereby leaving the actual production of the final product unchanged. Assessment of this approach at Bauhaus Luftfahrt aims at the identification of environmentally and economically viable strategies for the renewable production of carbon fibres.
After identification of several technically feasible processes yielding renewable acrylonitrile, three most promising options were selected for detailed analysis:
Glycerol is a by-product of biodiesel production from vegetable oil and, hence, available in large quantities. It can be chemically converted into acrylonitrile.
Ethanol is a renewable mass commodity and convertible into propene in a few synthesis steps. Propene, in turn, represents the key educt in conventional synthesis of acrylonitrile. However, initial analyses indicated that propene production from ethanol is relatively energy-intensive.
An interesting variation of the ethanol pathway results from converting synthesis gas (a mixture of hydrogen and carbon monoxide) into propene. Synthesis gas can be produced from a broad variety of renewable sources, including many types of biomass. Therefore, this process path offers high feedstock flexibility.
Future work will focus on the in-depth assessment of the performance potentials of these pathways in terms of energy demand, associated emissions and costs.