The Contaminant Challenge: Boosting Efficiency and Flexibility with Advanced Pretreatment

Introduction

As the renewable fuels industry grows, the shift from traditional fossil-based feedstocks to fats, oils, and greases (FOG) brings new challenges—chief among them, managing contaminants. The choice of pretreatment technology is critical, as it directly impacts downstream processing, product quality, and operational efficiency.

The Role of Pretreatment in Renewable Fuel Production

The hydroprocessed esters and fatty acids (HEFA) route to sustainable aviation fuel (SAF) and hydrotreated vegetable oil (HVO) for renewable diesel are leading the transition to cleaner fuels. While the core conversion processes are well established, the real opportunity for improvement lies in pretreatment the crucial first step that prepares raw materials for efficient and reliable conversion.

Feedstocks for SAF and HVO often contain high levels of impurities such as chlorides, phosphorus, and metals. These contaminants can cause premature catalyst deactivation, mechanical corrosion, and process instability. As producers increasingly turn to waste oils and lower-quality feedstocks, the need for robust pretreatment becomes even more urgent.

Traditional vs. Advanced Pretreatment Methods

Historically, physical refining using water or acid degumming, mechanical separation, and bleaching earth has been the standard for edible oils and oleochemicals. While effective for mild impurities, achieving ultra-low contaminant levels requires additional steps and investment.

Sulzer’s advanced pretreatment technology takes a different approach. Instead of relying on mechanical or chemical separation, it uses thermal cracking to break down fats and oils into lighter hydrocarbons. This process reduces metals, phosphorus, and chlorides to levels that protect downstream hydrotreaters. Importantly, it does not require catalysts or chemicals, and mechanical separation is eliminated.

Benefits of Thermal Cracking Pretreatment

• Ultra-Low Contaminant Levels: Commercial operations have achieved phosphorus and chlorides below 1 wppm and metals below 10 wppm—well within safe limits for hydrotreating.

• Feedstock Flexibility: The process can handle a wide range of feedstocks, including distillers corn oil, soybean oil, used cooking oil, and waste chicken fats.

• Reduced Hydrogen Consumption: By partially converting feedstocks and removing oxygen via decarboxylation, hydrogen requirements downstream are slashed by up to 60%. This allows for a smaller hydrotreater and significant capital savings.

• Simplified Process: Deoxygenation and isomerization, which typically require two stages, can often be accomplished in a single reactor.

• Economic and Environmental Gains: Lower utility requirements, reduced hydrogen generation, and smaller equipment translate to a lower carbon footprint—up to 13% reduction in carbon intensity for a 10,000 barrel-per-day HVO complex, equating to 125,000 metric tons of CO₂ saved annually.

  
  

Optimizing Product Quality and Economics

Adjusting the internal recycle rate in the pretreatment unit allows operators to fine-tune product properties. For example, with a once-through design, thermal cracking followed by hydrotreating can produce diesel with a cloud point of 28°F (-2°C) and hydrogen consumption of 1,230 scf/bbl (200 Nm³/m³). Increasing internal recycling further reduces cloud point and hydrogen consumption.

Key Takeaways

• Pretreatment is a critical step that determines the efficiency, flexibility, and economics of renewable fuel production.

• Thermal cracking pretreatment enables the use of lower-quality feedstocks, reduces hydrogen consumption, and lowers both capital and operating costs.

• The technology delivers ultra-low contaminant levels, protects downstream equipment, and supports compliance with increasingly stringent carbon intensity targets.

  
  

By investing in advanced pretreatment, producers can unlock new levels of efficiency, flexibility, and sustainability paving the way for a cleaner, more resilient energy future for more information, please feel free to contact us.