Abstract
The conversion of energy sources such as coal, biomass and natural gas to hydrocarbons is crucial in the energy industry. The Fischer-Tropsch (FT) process has gained importance throughout decades as an environmentally friendly and cost-effective method of converting energy sources to product streams of fuel and chemicals. However, even after its longstanding application, there remains a lack of understanding in the intrinsic proceedings of the wide-ranging set of reactions associated with the process. From a technical and commercial point of view, the main challenge in FT Synthesis is maximizing the selectivity to desired products and improving carbon utilization efficiency. Revisiting fundamental FT theory is a crucial step towards a comprehensive understanding of the FT process and the optimisation of selectivity and carbon efficiency thereof. The purpose of this study was to gain insight on the fundamental aspects involved in experimental FT synthesis. The effect of operating conditions, temperature and pressure, on the FT selectivity and activity were studied in a laboratory scale fixed bed reactor system. The second objective was to better understand the kinetic behaviour of iron-based FT processes by conducting a kinetic model discrimination using the acquired experimental data. To achieve this, a Fe/Al2O3 catalyst containing 10 wt.% Fe was prepared by the incipient impregnation of Fe(NO3)3.9H2O on an Al2O3 support. The characterisation of the catalyst was carried out through using X-ray Diffraction (XRD), Temperature Programmed Reduction (TPR) and Brunauer-Emmet-Teller (BET) techniques. 0.5g of the prepared catalyst was loaded in a fixed bed reactor (L = 400 mm; ID = 6 mm) and reduced for 6 hours at 300°C and an additional 2 hours at 330 °C at atmospheric pressure using a flow of pure H2. The FT reactions were carried out at temperatures and pressures that were varied from 250 – 300 °C and 1-20 bar, respectively. A constant inlet flow of syngas was kept at 10 ml/min during the reaction. An online GC connected to the reactor was used to analyse the products...
M.Tech. (Chemical Engineering)