Unravelling the influence of catalyst properties on light olefin production via Fischer-Tropsch synthesis: A descriptor space investigation using Single-Event MicroKinetics

Kinetic models constitute a useful tool to provide fundamental insights for catalyst development. Single-Event MicroKinetic modelling (SEMK) is a versatile strategy to assess complex reactions with a limited number of parameters. Particularly for Fischer-Tropsch synthesis SEMK modelling has focused on explaining the performances of individual catalysts within a wide range of operating conditions. In this work, we extend the capabilities of the SEMK modelling approach to investigate the influence of variation in catalyst properties i.e. catalyst descriptors, on the yield of desired component, light olefins (C-2 -C-4 =). We explore the catalyst descriptor space around three literature-reported iron-based catalysts. The three catalyst descriptors, i.e. atomic chemisorption enthalpies of hydrogen (Q(H)), carbon (Q(C)), and oxygen (Q(O)) in the SEMK modelling approach have a combined effect on the conversion, whereas the selectivity to light olefins is found to be less sensitive to Q(O). These effects can be rationalized in terms of relative surface coverages of different species, leading to different dominant reaction pathways, and thus resulting in product yield variations. Using this approach, a promising catalyst with catalyst descriptors, Q(H) approximate to 234 kJ/mol, Q(C) approximate to 622 kJ/mol and Q(O) approximate to 575 kJ/mol resulting in 55% light olefins yield with lower methanation and long-chain hydrocarbon formation, is identified.

Automated summary

In this research, the SEMK modelling approach was used to investigate the impact of catalyst descriptors on the yield of light olefins, identifying a promising catalyst with specific Q(H), Q(C), and Q(O) values that resulted in a high yield of light olefins. The combined effect of the three catalyst descriptors on conversion was observed, while the selectivity to light olefins was found to be less sensitive to Q(O). These effects were rationalized in terms of relative surface coverages of different species, leading to variations in dominant reaction pathways and product yield.