This bachelor's thesis investigates the direct thermochemical catalytic conversion of CO₂ with hydrogen into intermediate products that could subsequently be used in the production of sustainable or renewable aviation fuels. The aim was to investigate the effect of temperature on CO₂ conversion and product distribution. A sodium-promoted copper–iron (Na–CuFe) catalyst was synthesised and used together with a commercial 5 wt.% Cu/H-ZSM-5 catalyst in a continuous packed-bed flow reactor. Reactions were carried out at 270, 300, 330 and 360 °C at a constant pressure of 20 bar. The gas phase was analysed by micro-GC and the liquid phase by GC–MS. CO₂ conversion increased with increasing temperature, reaching 36.04% at 330 °C, and decreased slightly at 360 °C. The highest CO mole fraction was measured at 330 °C, indicating a pronounced reverse water–gas shift (RWGS) contribution, while methane mole fraction and selectivity increased markedly at the higher temperatures. Several oxygenated compounds were detected in the liquid samples, including methanol, while ethanol and methyl acetate were tentatively identified in the sample collected during the later stage of the sequential experiment. Because the temperature stages at 330 and 360 °C were performed sequentially, the effect of temperature at these two conditions cannot be fully separated from time-on-stream effects. Based mainly on the gas-phase results, 330 °C was the most promising among the investigated conditions. Further optimisation of process parameters, such as higher pressure, gas velocity, and the CO₂/H₂ ratio, could increase CO₂ conversion and the yield of liquid products in the hydrocarbon fraction relevant to SAF production. Tuning the Cu/Fe ratio in the catalyst could influence Fischer–Tropsch activity and improve selectivity towards the desired products. No products that could be directly classified as SAF were detected.
|
