The iron and steel industry is responsible for 30% of all industrial CO2 emissions, largely emitted via hot Basic Oxygen Furnace (BOF) gas (CO, H2, CO2). Gas fermentation can convert the BOF gas into valuable chemicals such as the disinfectant and platform chemical isopropyl alcohol (IPA), which is currently only produced with petrochemical cracking. The goal of this research was to model the state-of-the-art industrial-scale BOF gas fermentation to IPA and identify the key process parameters affecting technical performance. The designed and modelled industrial-scale process was based on the published LanzaTech technology with Clostridium autoethanogenum. In the process model, the IPA is purified through extractive distillation with pure glycerol as an entrainer. During sensitivity analysis, eleven process parameters were investigated for their effect on the eighteen chosen technical Key Performance Indicators (KPIs). These process parameters are (product selectivity (YIPA/CO), CO volumetric mass transfer rate (VMTCO), CO conversion, reactor dilution rate (D), temperature off-gas condenser, biomass separation liquid loss, extractive distillation glycerol mole fraction, extractive distillation molar reflux ratio, glycerol recycle purge, broth recycle purge and anaerobic digestion waste conversion). The sensitivity analysis identified that the key technical parameters affecting the KPIs are the gas fermentation parameters (CO conversion, VMTCO, YIPA/CO, and D) as well as the biomass filtration liquid loss. Moreover, increasing CO conversion, VMTCO, YIPA/CO as well as decreasing D and the biomass filtration liquid loss all individually had the greatest positive impact on the KPIs. Thus, this study has successfully synthesised and modelled a state-of-the-art industrial-scale BOF gas fermentation to IPA process and identified the key process parameters to improve its technical process performance. These findings can be used both to optimise the BOF gas fermentation to IPA process, and perform further economic evaluations and environmental impact assessment.@en