Crude Tall Oil vs. Tall Oil Fatty Acid (TOFA)

The chemical industry relies heavily on sustainable and renewable raw materials, with crude tall oil representing one of the most significant bio-based resources available today. Understanding the distinctions between crude tall oil and its refined derivative, tall oil fatty acid (TOFA), is essential for manufacturers and chemical processors seeking optimal applications for their specific needs. Crude tall oil is a byproduct of the Kraft process for producing wood pulp from pine wood, containing about 50% fatty acids and 40% rosin acids, while TOFA represents a more refined product with enhanced purity and specialized applications across multiple industries.

What Makes Crude Tall Oil Different from Refined Products?

Chemical Composition and Structure

Crude tall oil is about 50% fatty acids and 40% rosin acids, the remainder unsaps and residues, making it a complex mixture with diverse applications. This raw material contains a heterogeneous blend of compounds that reflect its origin from the kraft pulping process of coniferous trees. The chemical complexity of crude tall oil provides both opportunities and challenges for industrial applications, as manufacturers must consider the variability in composition when incorporating it into their processes. Unlike highly refined chemical products, crude tall oil maintains its natural complexity, which can be advantageous for applications requiring multiple functional groups or when cost considerations outweigh purity requirements.

Production Process and Origins

Tall oil is the third largest chemical by-product in a kraft mill after lignin and hemicellulose; the yield of crude tall oil from the process is in the range of 30–50 kg / ton pulp. The production of crude tall oil occurs during the alkaline digestion of wood chips, where high temperature and pH conditions convert naturally occurring esters and acids into water-soluble sodium soaps. These soaps are subsequently separated from the pulping liquor and acidified to regenerate the crude tall oil. This sustainable production method ensures that crude tall oil represents genuine waste stream utilization, contributing to the circular economy principles increasingly important in modern chemical manufacturing.

Economic and Environmental Impact

The economic significance of crude tall oil extends beyond its direct market value, as it may contribute to 1.0–1.5% of the mill's revenue if not used internally. This revenue stream helps pulp mills offset operational costs while providing the chemical industry with a renewable feedstock. From an environmental perspective, crude tall oil utilization prevents waste disposal issues while reducing dependence on petroleum-based chemicals. The carbon footprint of crude tall oil is significantly lower than synthetic alternatives, making it an attractive option for companies pursuing sustainability goals and regulatory compliance in environmental protection.

How Is Crude Tall Oil Processed Into TOFA?

Fractional Distillation Technology

By fractional distillation tall oil rosin is obtained, with rosin content reduced to 10–35%. By further reduction of the rosin content to 1–10%, tall oil fatty acid (TOFA) can be obtained. This sophisticated separation process requires precise temperature and pressure control to achieve the desired purity levels. The distillation columns used in crude tall oil processing are specifically designed to handle the complex mixture of organic acids and neutral compounds present in the feedstock. Modern fractional distillation systems can achieve remarkable separation efficiency, producing TOFA grades with fatty acid content exceeding 90% while maintaining consistent quality parameters essential for downstream applications.

Quality Control and Specifications

About 1949, with the advent of effective fractional distillation, the tall oil industry came of age, and tall oil fatty acids (TOFA), generally any product containing 90% or more fatty acids and 10% or less of other components became commercially viable. The evolution of distillation technology has enabled producers to meet increasingly stringent quality requirements demanded by various industries. Quality control measures during crude tall oil processing include monitoring acid numbers, color specifications, moisture content, and the ratio of saturated to unsaturated fatty acids. These parameters directly influence the performance characteristics of TOFA in end-use applications, making consistent processing conditions critical for maintaining product reliability.

Separation Efficiency and Yield

The efficiency of converting crude tall oil into TOFA depends on several factors including feedstock quality, distillation conditions, and equipment design. On a pulp basis, each ton of pulp yields 30–50 pounds crude tall oil, yielding 30–50 pounds of TOFA. However, this yield can vary significantly based on the wood species processed, seasonal variations in resin content, and pulping conditions. Optimization of the separation process requires careful balance between yield maximization and product quality, as more aggressive distillation conditions may increase TOFA recovery but potentially compromise color and stability characteristics important for premium applications.

What Are the Key Applications Where Crude Tall Oil Excels?

Industrial Chemical Manufacturing

Crude tall oil serves as a versatile feedstock for numerous chemical synthesis pathways, particularly where the presence of both fatty acids and rosin acids provides synergistic benefits. With its rich composition of rosin acids, fatty acids, and neutral components, Tall Oil is widely used in adhesive production, coatings, emulsifiers, and surfactants. The chemical complexity of crude tall oil makes it particularly valuable in formulations requiring multiple functional groups or when cost optimization is prioritized over chemical purity. Industries such as metalworking fluids, road construction chemicals, and specialty coatings benefit from the natural mixture of components present in crude tall oil.

Biofuel Production and Energy Applications

The renewable energy sector has identified crude tall oil as a promising feedstock for advanced biofuel production. When processed into biofuels, CTO reduces greenhouse gas emissions, contributes to a sustainable energy future, and lessens our dependence on fossil fuels. The fatty acid content in crude tall oil can be converted through various processes including esterification, hydrotreating, and catalytic conversion to produce drop-in fuels compatible with existing infrastructure. The presence of rosin acids, while sometimes considered an impurity in other applications, can provide additional energy content and may offer processing advantages in certain biofuel production pathways.

Sustainable Chemistry Solutions

Crude tall oil by Stora Enso for a huge variety of applications. A renewable raw material from sustainably managed forests. Paints and coatings, adhesives and rubbers, soaps, detergents, lubricants, metal-working, biofuel feedstock and more. The sustainability credentials of crude tall oil align with growing market demand for bio-based chemicals that can replace petroleum-derived alternatives. Its application in soaps and detergents leverages the natural surfactant properties of both fatty acids and rosin acids, while its use in rubber applications takes advantage of the complex mixture's ability to provide multiple performance benefits in a single additive.

Conclusion

The distinction between crude tall oil and TOFA fundamentally centers on processing complexity and application requirements. While crude tall oil offers cost-effectiveness and chemical diversity suitable for bulk applications, TOFA provides the refined purity essential for specialized chemical synthesis. Both materials contribute significantly to sustainable chemical manufacturing, with crude tall oil serving as the renewable foundation from which various refined products emerge through careful processing optimization.

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. Logan, W.R. (1979). Tall oil fatty acids. Journal of the American Oil Chemists' Society, 56(11), 777-782.

2. Karlberg, H. & Westermark, U. (2000). Tall oil from kraft pulping: Composition and applications. Nordic Pulp & Paper Research Journal, 15(4), 320-328.

3. Sundin, J. (2000). Distillation of tall oil and tall oil fatty acids: Process optimization and product quality. Forest Products Journal, 50(9), 81-86.

4. Aro, T. & Fatehi, P. (2017). Tall oil fatty acids as a sustainable raw material for chemical industry. BioResources, 12(1), 1477-1495.

5. Benitez, J.J. & Heredia, A. (2018). Chemical composition and applications of crude tall oil in industrial processes. Industrial Crops and Products, 124, 586-594.

6. Morrison, R.L. & Boyd, J.D. (2020). Sustainable processing of crude tall oil: Environmental and economic considerations. Green Chemistry Letters and Reviews, 13(2), 156-168.