Driving the Future of Biofuel Refineries: Innovative Pretreatment Technologies

As the world races to meet ambitious emission targets, the demand for clean fuels from renewable sources is surging. Renewable diesel also known as hydrotreated vegetable oil (HVO)—has emerged as a leading alternative for road transportation, while sustainable aviation fuel (SAF) production increasingly relies on hydrotreated esters and fatty acids (HEFA). Both pathways utilize hydroprocessing technologies to convert fats, oils, and greases (FOG) into high-quality, drop-in fuels.

However, the real key to unlocking the full potential of these processes lies upstream, in the critical step of pretreatment.

The Critical Role of Pretreatment

Pretreatment is the first line of defense against impurities in renewable feedstocks. Contaminants such as chlorides, phosphorus, and metals can wreak havoc on hydrotreating catalysts, leading to premature deactivation, corrosion, and process instability. As the industry shifts toward lower-quality feedstocks like used cooking oil (UCO) and low-grade tallow, the need for robust pretreatment technologies has never been greater.

Historically, physical refining a multi-step process involving acid or enzymatic degumming, adsorption, and mechanical separation has been the standard.

While effective for edible oils and biodiesel, physical refining struggles to achieve the ultra-low contaminant levels required for HEFA and HVO production without significant additional investment.

The Rise of Thermal Cracking Pretreatment

Newer pretreatment technologies, such as thermal cracking, are transforming the landscape. Inspired by refinery visbreaking, thermal cracking uses heat to break down fats and oils into lighter hydrocarbons. This process reduces metals, phosphorus, and chlorides to levels that protect downstream hydrotreaters without the need for catalysts, chemicals, or mechanical separation.

Thermal cracking also generates a stream of light hydrocarbons (C1–C4) and removes oxygen via decarboxylation, resulting in a partially converted product that requires less hydrogen in the hydrotreater. This not only reduces hydrogen consumption by up to 60% but also allows for a smaller, more cost-effective hydrotreater. In some cases, deoxygenation and isomerization can be combined into a single reactor, slashing capital expenditures by as much as 50%.

Commercial Performance and Feedstock Flexibility

Commercial operations have demonstrated the effectiveness of thermal cracking pretreatment across a range of feedstocks, including distillers corn oil, soybean oil, UCO, and waste chicken fats. Impurity levels consistently fall below 1 wppm for phosphorus and chlorides and below 10 wppm for metals well within the specifications for hydrotreating.

This flexibility enables producers to utilize lower-quality feedstocks that would otherwise be discarded, increasing the yield of saleable product and reducing waste.

Moreover, the ability to process a wider variety of feedstocks enhances the economic resilience of biofuel refineries.

Unlocking Co-Processing Potential

Thermal cracking also overcomes barriers to co-processing renewable feedstocks with petroleum-derived diesel and jet fuel. Traditional limitations such as higher reaction exotherms and oxygen content restrict co-processing to 10–15% of the total feed rate.

With pretreated, partially converted feedstocks, the allowable percentage of renewable material can be significantly increased, enabling greater integration with existing refinery operations.

Lowering Carbon Intensity

The adoption of renewable feedstocks is a major driver of sustainability in the transportation sector.

The choice of pretreatment, hydrotreating, and hydrogen generation technologies directly impacts a facility’s carbon footprint. Thermal cracking pretreatment reduces carbon intensity (CI) by up to one-third compared to conventional processes, thanks to lower hydrogen consumption and the elimination of imported natural gas for hydrogen generation.

For a 10,000 barrel-per-day HVO complex, this translates to a reduction in CO₂ emissions of up to 30,000 tons per year. The overall CI of the final fuel can be up to 90% lower than that of petroleum-derived fuels.

Key Takeaways

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

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

• Commercial performance has proven the technology’s effectiveness across a wide range of feedstocks.

• Co-processing potential is significantly enhanced, allowing for greater integration with existing refinery infrastructure.

• Carbon intensity is dramatically reduced, supporting compliance with stringent emission targets and driving the transition to a more sustainable energy future.

  
  

With innovative pretreatment technologies like thermal cracking, biofuel refineries can overcome the contaminant challenge, boost efficiency, and lead the way toward a cleaner, more flexible, and sustainable energy landscape, if you want more information please feel free to contact us.