Chemical modification of beef tallow for lubricant application

Authors: Yosief, Hailemichael; Sarker, Majher; Bantchev, Grigor; Dunn, Robert - Bob; Cermak, Steven - Steve

Submitted to: Industrial and Engineering Chemistry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2022
Publication Date: 6/29/2022
Citation: Yosief, H.O., Sarker, M.I., Bantchev, G.B., Dunn, R.O., Cermak, S.C. 2022. Chemical modification of beef tallow for lubricant application. Industrial and Engineering Chemistry Research. 61(27):9889-9900. https://doi.org/10.1021/acs.iecr.2c01207.
DOI: https://doi.org/10.1021/acs.iecr.2c01207

Interpretive Summary: In this study a low-value bio-based material, inedible beef tallow collected from a local rendering house was chemically modified at the molecular level to use in lubrication applications. The modified beef tallow was analyzed using a combination of different analytical techniques to determine its application-based properties. The modified beef tallow offers better oxidation stability, improved properties to be used in cold conditions, and higher density and kinetic viscosity than regular beef tallow. This study demonstrated that inedible animal fats like beef tallow can be considered as an alternative renewable source for generating value-added products such as ingredients for the bio-lubricant industry.

Technical Abstract: The possible application of using beef tallow as a bio-lubricant by changing its physical and tribological properties through chemical modification has been explored. Regular beef tallow (RBT) was chemically modified by introducing an isopropyl group into the unsaturated fatty acid chains of the triglyceride using the industrially produced reagent, ethylaluminum sesquichloride. The resulting branched beef tallow (BBT) was characterized using a combination of different analytical techniques including GC-MS, NMR, FTIR, and GPC. GC-MS and NMR results indicate complete saturation (>95%) of the RBT double bonds with the attachment of isopropyl groups. GPC indicates the presence of oligomers in BBT. The physico-chemical and tribological properties of the RBT and BBT as well as their blends with high oleic sunflower oil (HOSuO) or polyalphaolefin (PAO-6) were evaluated. BBT has better oxidative stability than RBT, due to the elimination of the unsaturation. The introduced branching in BBT led to improved cold-flow properties (cloud point and pour point) compared to RBT, both as neat materials and as blends in HOSuO or PAO-6. The BBT also displayed higher density and kinematic viscosity than the RBT, possibly due to the presence of oligomers. The introduction of branching was also accompanied with higher solubility in HOSuO and POA-6, but a lower viscosity index. Both RBT and BBT displayed good lubricity as HOSuO and were effective lubricity improvers when added to PAO-6, even at low (5 wt. %) concentrations. This study indicates that by introducing branching in RBT we can prepare biobased materials, which can be blended into lubricants with improved properties.