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

Abstract

Abstract 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 modeling 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 (C2\n − C4=). We explore the catalyst descriptor space around three literature-reported iron-based catalysts. The three catalyst descriptors, i.e. atomic chemisorption enthalpies of hydrogen (QH),carbon (QC), and oxygen (QO) 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 QO. 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, QH\n ≈ 234 kJ/mol, QC\n ≈ 622 kJ/mol and QO\n ≈ 575 kJ/mol resulting in 55% light olefins yield with lower methanation and long-chain hydrocarbon formation, is identified.