CO
Sugars
Fermentation
Dehydration
Ethanol
C sugars
Distiller’s grain
Starches
H O
C /C sugars
Hydrolysis
Green gasoline
Direct conversion
Bio-oil
Pyrolysis/thermal depolymerisation
Hydrotreating
H O
Light fraction
Syngas
Fischer - Tropsch
Green diesel
Gasi cation
Natural oils
H O
Alcohol synthesis
FCC
Co-feed
Optional petroleum
Hydrotreating
H O
FAME/FAEE
Transesteri cation
Glycerine
Figure 2 Integration of biomass conversion processes within a refinery
mixing the feedstock with hydrogen in a high- pressure reactor with a catalyst composed of nickel, cobalt, and molybdenum metals supported on alumina. This setup removes impurities such as sulphur, nitrogen, and metals while saturating olefins and aromatics to improve the stability and combustion properties of the final products. Vegetable oils and animal fats are particularly well-suited for hydrotreating, producing renewable diesel and jet fuel by hydrogenating triglycerides and free fatty acids, removing oxygen, and creating hydrocarbons similar to those from fossil fuels. This process reduces emissions to produce fuels compatible with existing infrastructure, and enhance fuel stability and performance. The main challenge is the variability in biofeedstock quality, which can affect catalyst efficiency and longevity. Refineries may need to adjust operating conditions or modify existing units to optimise biofeedstock processing. Some refineries opt to co-process fats and oils with fossil streams, while others have dedicated hydrotreaters for their biostreams.
Integration with fluid catalytic cracking unit Fluid catalytic cracking (FCC) units are crucial for converting heavy hydrocarbons into lighter, more valuable products. Integrating pyrolysis oils from biomass into FCC units allows refineries to produce renewable fuels and chemicals using existing infrastructure. After pretreatment to remove impurities that could poison the FCC catalyst, biofeedstocks can be blended with fossil-derived streams and fed to the FCC unit. The blend is heated to around 500°C, where the hydrocarbons vaporise, mix with the catalyst, are cracked, and then separated into various product streams, including gasoline, light olefins, light cycle oil (LCO), and heavy cycle oil (HCO). This integration offers benefits like producing renewable fuels and reducing carbon intensity. Again, introducing biocomponents brings challenges due to feedstock variability and potential catalyst poisons. As with any change in feedstock there is a need for process optimisation. The variable composition and quality of bio-based feedstocks affects the cracking process, while contaminants like metals
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