Excellent Properties of Dimer Fatty Acid Esters as Biolubricant Produced by Catalyst‐ and Solvent‐Free Esterification

• Published in: European journal of lipid science and technology 2019-11, Vol.121 (11), p.n/a
• Main Authors: Armylisas, Abu Hassan N., Fauzi, Siti H. M., Mohd, Noor K., Yeong, Shoot K., Zainab, Idris, Azwadi, Che Sidik N.
• Format: Article
• Language: English
• Subjects: Alcohol; biodegradable; biolubricant base stock; Biomedical materials; C36 dimer acids; Catalysts; Chain branching; Cold flow; dimer fatty acid esters; Dimers; Esterification; Esters; Fatty acids; Flow stability; Kinematic viscosity; Low temperature; Lubricants; Molecular sieves; Properties (attributes); self‐catalyzed esterification; Solvents; Transesterification; Viscosity
• ISSN: 1438-7697; 1438-9312
• DOI: 10.1002/ejlt.201900228

Currently most technologies available to produce esters require acid or base catalysts for esterification or transesterification reactions. Production of dimerate esters (DE) exhibiting potential as a biolubricant for low temperature applications using catalyst‐ and solvent‐free approaches is presented in this article. Hydrogenated C36 dimer acid and alcohol are reacted under the following conditions: dimer acid/alcohol (1:4.5 molar ratio), 150–200 °C, 24 h, 3Å molecular sieve (15% w/w). The performances of four DE species—dibutyl, dihexyl, di‐(2‐ethylhexyl), and dioctyl dimerate—as lubricant base stocks are evaluated by kinematic viscosity, viscosity index, cloud and pour point (cold flow properties) as well as oxidative stability, and compared with commercial synthetic lubricant base stock and DE, Radialube 7121. High viscosity indexes ranging between 129 and 138 are observed for the synthesized DEs, which are comparable with two commercial base stock, polyalpha olefin (PAO), and polyolester (POE). Significantly low pour point, less than −42 °C, is observed for di‐(2‐ethylhexyl) dimerate attributed to the branching of the side chain. The DEs are categorized as ISO VG 68 based on their viscosity according to ISO 3448 classification and show potential as biolubricant with high viscosity index and excellent cold flow properties. Practical Applications: DFAE obtained have high potential to be used as lubricant base stock for equipment and machinery operating at extremely low temperature. A green technology is developed to produce a biolubricant, dimer fatty acid ester (DFAE) derived from C36 dimer acid without the need for catalyst and organic solvent. The synthesized DFAE exhibits excellent cold flow properties (pour point and cloud point) and high viscosity index suitable for operation at extremely low temperature conditions.