Novel plasma catalytic systems for Fischer-Tropsch reactions : intensified gas-to-liquid fuel production

• Main Author: Al-Harrasi, Wail Saif Salim
• Published: University of Newcastle Upon Tyne 2011
• Subjects: 662.88
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.578549

One of the impacts of climate change is the emergence of food, energy and water shortages which can be circumvented through intensified technologies in agriculture, energy and chemical/biological processes. Furthermore, depleting fossil fuel reserves requires the establishment of alternative sustainable energy resources. Biomass based energy and chemicals technology is an important component of sustainable development which can be integrated with food and water generation. However, due to distributed nature of biomass, biomass based energy technology needs to be distributed generation which would benefit from low temperature and pressure operation. Syngas produced from gasification of waste/biomass can be. converted to power or liquid fuel after cleaning. Although process intensification (PI) is still in its infancy, potentially, it is highly suitable for the distributed production of power and liquid fuels. The objective of this study is to develop a syngas-to-liquid fuel conversion process suitable for distributed production using principles of PI through the intensification of Fischer Tropsch Synthesis (FTS). The first approach was by using structured catalysts in monolithic forms for FTS. The second approach was to couple the structured catalyst with non thermal plasma by using dielectric barrier discharge (DBD) in hybrid FTS reactors. A hybrid reactor was designed and fabricated to test this novel catalytic system. Co and Co/Cu catalysts were prepared and characterised using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and transmission electron microscopy. The reactor was used in the FTS using H, and CO under various processing conditions (temperature, pressure, Hz/CO molar ratio, gas flowrate and plasma power) and the products were analysed using gas chromatography. It is shown that Co/Cu catalyst in plasma assisted FTS was feasible, converting up to 38% of CO at 90W, 1 bar, Hz/CO= 2, 25ml/min and 25°C. This conversion was obtained at 230°C and 6 bar in conventional FTS. This research showed that DBD in FTS enables running the reaction at room temperature and atmospheric pressure avoiding the risks and costs associated with high pressure processes. It was also shown that plasma affected the activity of the catalysts, preventing it from agglomeration.