(192g) Decentralized Production of Renewable Hydrogen Based On Ethanol Using Co/CeO2 Catalysts

Rabenstein, G., Graz University of Technology
Hacker, V., Graz University of Technology
Siebenhofer, M., Graz University of Technology

Hydrogen represents a clean energy, which is efficient, economically attractive and non-polluting. It is produced mostly from fossil fuels and therefore CO2 emissions from the transformation process contribute to the greenhouse effect. Bio-ethanol can be obtained in large quantities as renewable fuel by fermentation of biomass and its high hydrogen content makes it to an ideal candidate for production of renewable hydrogen. The European Union Biofuels Directive increases the compulsory amount of ethanol added to petrol, so that ethanol will be available at the petrol-stations throughout Europe in the future. With this existing infrastructure the ethanol reforming process seem to be a promising way to produce hydrogen for the incipient hydrogen economy.

Different options of ethanol reforming (steam reforming, autothermal reforming and partial oxidation) have been investigated from thermodynamic perspective comparing coking probability, CO-content off reformate and energy requirement per H2 produced. Steam reforming seems to be the best option although more stringent coking boundaries are predicted.

The catalytic process of ethanol steam reforming is more complex than methanol reforming due to the necessity of the C-C bond breakage. Different catalyst systems based on transition metals (Ni, Cu, Co) and noble metals (Rh, Ru, Pt, Ir) supported over a wide range of oxides with different acid-base and redox properties have been proposed in the open literature. The main problem of the catalytic systems is to obtain a good hydrogen selectivity and deactivation due to the formation of carbonaceous deposits.

For this work Co/CeO2 and promoted Co/CeO2 catalysts systems are investigated. Co has been chosen from economical perspective compared to noble metals and CeO2 for its redox properties and known influence to reduce coking. Depending on the operation temperature different coking rates and coke deposits have been observed. At temperatures of 450-500°C strong coke deposits in form of carbon fibers without catalytic deactivation but reactor blocking have been observed.