The Development of Triglyceride-Based Additives and Their Lubricity Properties for Low Sulfur Fossil Diesel: A Review

Reducing the sulfur content in fossil diesel is recognized to create cleaner air. One of the efforts that can be made to reduce sulfur is involving the hydrodesulfurization process in the oil refinery. However, that process is responsible for decreasing the natural lubricating compounds in fossil diesel. Then, it results in the low lubricity of fossil diesel which increases friction and wears scars on the metal surface of machinery components. Therefore, it is necessary to use additives to improve the lubricity properties of fossil diesel. Additives can be derived from vegetable oil-based triglyceride compounds (bio-additives). The primary bio-additives class studied in lubricity improver is the ester group. Many challenges need to be addressed by researchers to obtain such a bio-additive to perform better. This paper focuses on bio-additives and their lubricity properties between 1995 and 2020. We review the bio-additives class and its effect on fossil diesel lubricity, the relationship between structure and lubricity, the bio-additives synthesis route, and the lubricity testing method. Finally, the challenges and future research direction in developing lubricity bio-additives for low sulfur diesel fossil are also highlighted (including the strengths, weaknesses, opportunities, and threats analysis and its strategies briefly), which will be an essential consideration in synthesizing new lubricity improver bio-additives for low sulfur diesel.