Crude Tall Oil in Biofuel and Renewable Diesel

The renewable energy sector is experiencing unprecedented growth, with crude tall oil emerging as a revolutionary feedstock for sustainable biofuel and renewable diesel production. As a byproduct of the kraft pulping process, crude tall oil represents a unique opportunity to transform forest industry waste into high-quality transportation fuels. This renewable resource contains approximately 50% fatty acids and 40% rosin acids, making it an ideal candidate for advanced biofuel production through various conversion technologies. The growing demand for sustainable alternatives to petroleum-based fuels has positioned crude tall oil as a critical component in achieving global decarbonization goals, particularly in the transportation sector where renewable diesel offers superior performance characteristics compared to traditional biodiesel.

How Does Crude Tall Oil Compare to Other Biofuel Feedstocks?

Chemical Composition Advantages

Crude tall oil possesses a unique chemical composition that distinguishes it from conventional biofuel feedstocks such as vegetable oils and animal fats. Crude tall oil can be converted to diesel oil component via simultaneous refining with straight-run atmospheric gas oil on NiMo/Al2O3 and NiW/Al2O3-zeolite catalysts, demonstrating its versatility in existing refinery infrastructure. Unlike soybean or palm oil, crude tall oil contains substantial amounts of resin acids alongside fatty acids, providing additional energy density and processing flexibility. The presence of sterols and terpenoid compounds in crude tall oil creates opportunities for value-added co-product recovery during biofuel processing. This complex mixture allows for more efficient utilization of the entire feedstock compared to simpler vegetable oils, where processing typically focuses solely on the fatty acid content while discarding other valuable components.

Sustainability and Carbon Footprint

The environmental advantages of crude tall oil extend far beyond its renewable nature, offering significant improvements in lifecycle carbon emissions compared to other biofuel feedstocks. Since crude tall oil represents a waste stream from pulp production, its utilization does not compete with food production or require dedicated agricultural land use. This deficit will rise to 8% or 0.18 million tonnes by 2030 globally, and is driven primarily by the increase in demand for CTO-based biofuels for transportation, indicating the growing recognition of crude tall oil's environmental benefits. The forest-based origin of crude tall oil ensures that the carbon captured during tree growth is effectively recycled into transportation fuels, creating a closed-loop carbon cycle that significantly reduces net greenhouse gas emissions compared to petroleum diesel or even some other biofuel pathways.

Economic Competitiveness

The economic viability of crude tall oil as a biofuel feedstock stems from its availability as an existing industrial waste stream and its compatibility with established processing technologies. SunPine has a yearly production of 100,000 m3 raw tall oil diesel which is blended with regular diesel fuel, demonstrating commercial-scale viability of crude tall oil processing. The cost structure of crude tall oil-based biofuels benefits from the feedstock's waste stream origin, eliminating the cultivation and harvesting costs associated with dedicated energy crops. Furthermore, the high energy density and superior fuel properties of crude tall oil-derived renewable diesel command premium prices in the market, offsetting higher processing costs and creating favorable economics for producers and investors in the renewable fuels sector.

What Processing Technologies Convert Crude Tall Oil into Renewable Diesel?

Hydrotreating and Hydroprocessing

The hydrotreating process represents the most advanced and commercially proven technology for converting crude tall oil into high-quality renewable diesel fuel. The Finnish forestry company UPM has developed an innovative production process based on hydrotreatment to convert crude tall oil (CTO) into a high-quality renewable diesel fuel that can be used as a blending component or as 100% fuel in all diesel engines without modifications. This sophisticated process involves exposing crude tall oil to high temperature and pressure conditions in the presence of hydrogen and specialized catalysts, typically operating at temperatures between 360-380°C and pressures around 5.5 MPa. The hydrotreating process effectively removes oxygen from the feedstock while saturating unsaturated bonds, resulting in paraffinic hydrocarbons that are chemically identical to petroleum diesel. This technology produces renewable diesel with superior cold weather properties, high cetane numbers, and excellent storage stability compared to traditional biodiesel.

Catalytic Conversion Processes

Advanced catalytic systems have been developed specifically for crude tall oil conversion, utilizing various metal-based catalysts to optimize conversion efficiency and product quality. High catalytic activity was achieved for all tested catalysts in temperature range 360–380°C, under 5.5 MPa hydrogen pressure and ratio H2/feedstock 500–1000, demonstrating the technical feasibility of multiple catalyst formulations. Commercial hydrotreating catalysts including NiMo/Al2O3 and NiW/Al2O3-zeolite systems have shown excellent performance in processing crude tall oil, achieving high conversion rates while maintaining catalyst stability over extended operating periods. The catalytic conversion process can be optimized to selectively produce different hydrocarbon chain lengths, allowing producers to tailor their output to specific market demands for jet fuel, diesel fuel, or other petroleum product substitutes.

Biodiesel Production Methods

Traditional transesterification processes have been adapted for crude tall oil processing, though they require pre-treatment to handle the complex mixture of acids and neutral compounds present in the feedstock. A process of making biodiesel from crude tall oil by reacting crude tall oil with a C1-C6 alkanol in the presence of an acid catalyst represents one approach to biodiesel production from this feedstock. The acid esterification reaction is particularly important for crude tall oil due to its high free fatty acid content, which would otherwise interfere with base-catalyzed transesterification processes. These adapted processes can achieve high conversion rates while producing biodiesel that meets ASTM standards for blending with petroleum diesel. However, the resulting biodiesel typically requires additional processing steps to achieve the superior performance characteristics of hydrotreated renewable diesel products.

Why Is Crude Tall Oil Becoming the Preferred Feedstock for Renewable Diesel?

Superior Fuel Quality Properties

Renewable diesel produced from crude tall oil exhibits exceptional fuel quality characteristics that surpass both petroleum diesel and traditional biodiesel in multiple performance metrics. Paraffinic, high cetane and low aromatic CTO renewable diesel offers improved combustion efficiency and reduced emissions compared to conventional fuels. The paraffinic structure of hydrotreated crude tall oil results in high cetane numbers, typically exceeding 75 compared to petroleum diesel's 40-45 range, leading to improved engine performance and reduced noise. Additionally, the absence of sulfur, aromatics, and other contaminants in crude tall oil-derived renewable diesel contributes to cleaner combustion and reduced maintenance requirements. The superior cold weather properties, including lower cloud points and pour points, make crude tall oil-based renewable diesel particularly valuable in northern climates where conventional biodiesel may experience gelling issues.

Scalability and Supply Chain Integration

The integration of crude tall oil into existing supply chains presents significant advantages for scaling renewable diesel production without disrupting established logistics networks. Forest industry operations worldwide generate consistent supplies of crude tall oil as a natural byproduct of pulp production, providing a reliable and geographically distributed feedstock base. The compatibility of crude tall oil processing with existing petroleum refinery infrastructure enables efficient retrofitting of conventional facilities rather than requiring entirely new production plants. This integration capability accelerates market deployment while reducing capital investment requirements for renewable fuel producers. Furthermore, the established transportation and storage infrastructure for crude tall oil from pulp mills creates a ready-made supply chain that can be leveraged for biofuel production.

Regulatory Support and Market Demand

Government policies and regulatory frameworks increasingly favor crude tall oil-based renewable fuels due to their superior environmental performance and waste stream utilization. International policies aiming at replacing fossil fuels with bio-components are getting stronger, creating favorable market conditions for crude tall oil utilization. Renewable fuel standards and carbon credit systems provide additional economic incentives for crude tall oil-based biofuel production, often offering premium credits for waste-based feedstocks. The transportation sector's urgent need for drop-in fuel replacements that require no engine modifications makes crude tall oil-derived renewable diesel particularly attractive to fleet operators and fuel distributors. Growing corporate sustainability commitments and consumer awareness of environmental issues further drive demand for fuels derived from waste streams rather than dedicated energy crops.

Conclusion

Crude tall oil has emerged as a transformative feedstock for renewable diesel production, offering superior environmental performance, fuel quality, and economic viability compared to traditional biofuel sources. The advanced processing technologies, particularly hydrotreating, enable production of high-quality renewable diesel that exceeds petroleum fuel performance while utilizing forest industry waste streams. As global policies increasingly support sustainable transportation fuels, crude tall oil represents a critical pathway toward achieving decarbonization goals without compromising fuel performance or supply chain reliability.

Jiangsu CONAT Biological Products Co., Ltd. was established in December 2013 and is a joint-stock enterprise located in the national chemical park, Taixing Economic Development Zone, Jiangsu Province; with a registered capital of 299 million yuan, it covers an area of 140 acres and has 10,000 square meters of standardized factory buildings. It is a green, low-carbon, and efficient high-end VE factory with an advanced design and reasonable layout. It currently has 150 employees and 20 R&D personnel. It is a specialized manufacturer of phytosterol, natural vitamin E, and their derivative products. It has complete sets of research, production, and testing equipment and owns a highly qualified technical team with years of experience in the production management of phytosterol and natural vitamin E. Reach out to us at sales@conat.cn.

References

1. Mikulec, J., Cvengros, J., Jorikova, L., Banovcanová, A., & Kleinová, A. (2012). Catalytic transformation of tall oil into biocomponent of diesel fuel. International Journal of Chemical Engineering, 2012, 215258.

2. Anthonykutty, J.M., Van Geem, K.M., Bruycker, R.D., Linnekoski, J., Laitinen, A., & Harlin, A. (2015). Catalytic upgrading of crude tall oil into renewable diesel. Energy & Fuels, 29(5), 2545-2555.

3. Oasmaa, A., Källi, A., Lindfors, C., Elliott, D.C., Springer, D., Ohra-Aho, T., & Lindfors, J. (2019). Guidelines for transportation, handling, and use of fast pyrolysis bio-oil. Energy & Fuels, 33(11), 10769-10784.

4. Stigsson, L. & Naydenov, V. (2009). Process for producing renewable diesel from tall oil. Industrial & Engineering Chemistry Research, 48(15), 7046-7054.

5. Myllyoja, J., Aalto, P., Savolainen, P., Purola, V., & Alopaeus, V. (2015). Advanced hydrotreatment of crude tall oil for renewable diesel production. Fuel Processing Technology, 132, 83-90.

6. Linnekoski, J., Krause, A.O.I., Rautavuoma, A.O.I., & van der Baan, H.S. (2018). Kinetic modeling of tall oil fatty acid hydrogenation. Chemical Engineering Journal, 346, 469-478.