Chemical Modification of Beef Tallow for Lubricant Application

Abstract

The possible application of beef tallow as a biolubricant by improving its physicochemical properties through chemical modification has been explored. The unsaturated fatty acid chain of the regular beef tallow (RBT) was alkylated with isopropyl groups in the presence of ethylaluminum sesquichloride. The alkyl-branched beef tallow (BBT) was characterized using a combination of various analytical techniques, including gas chromatography–mass spectroscopy (GC–MS), nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy, and gel permeation chromatography (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 physicochemical and tribological properties of the RBT and BBT as well as their blends with polyalphaolefin (PAO-6) or high-oleic sunflower oil (HOSuO) were evaluated. BBT has better oxidative stability than RBT, due to the elimination of the unsaturation. The introduction of alkyl groups into beef tallow led to improved low-temperature properties compared to RBT, both as neat materials and as blends in HOSuO or PAO-6. The BBT also displayed higher density (0.9030 vs 0.8969 g/mL) and kinematic viscosity (112.7 vs 44.2 mm2/s) than the RBT, possibly due to the presence of oligomers. The introduction of branching was also accompanied by higher solubility in HOSuO and POA-6, but a lower viscosity index (186 vs 149). Both RBT and BBT displayed good lubricity as HOSuO and were effective at improving PAO-6 lubricity at low concentrations (5 wt %). This study indicates that introducing branching into RBT produces new biobased materials, which can be blended into lubricants with improved properties.

Green Synthesis and Property Analysis of Biolubricants Based on Structural Variations

“…To analyze the FA composition of the synthesized triesters, T-IS, T-IO, T-OA, G-IO, and G-OA, an Agilent gas chromatograph (GC, model 8890N) equipped with an Agilent mass-selective (MS) detector (model 5977N) and an SP-2380 column (30 m × 0.25 mm × 0.2 μm) from Supelco was used. FA methyl esters (FAMEs) of T-IS, T-IO, T-OA, G-IO, and G-OA were produced via transesterification reaction following the published procedures ,,, to be analyzed by the gas chromatography-mass spectroscopy (GC-MS). The following parameters were set on GC-MS for the sample analysis: The column was heated to 70 °C for 1 min, ramped up to 250 °C at a rate of 30 °C/min, and then maintained at 250 °C for 10 min.…”

“…Several methods have been studied previously to improve the lubricant properties of the natural lipids. For example, selective hydrogenation reduces the percentage of unsaturation on FA chains in TGs and thus makes them oxidatively more stable. , Introduction of branching on FA chains in TGs either by alkylation ,, or epoxidation ,,, has been found to improve their viscosity index, oxidative stability, flash points, lubricity, and anti-corrosion properties. The replacement of the glycerol back bone in TG with a polyol group has become a popular technique in developing biolubricants.…”

Isopropyl‐branched lard and its potential application as a bio‐based lubricant

“…Isopropyl branched lard (BL) was synthesised using reaction conditions as described in previous work. 43,44 The synthetic scheme for the hydro-alkylation of RL and transesterification of the alkyl branched lard is shown in (Scheme 1). In short, regular lard (RL) (60 g, $0.07 mole) was placed in a 500-mL reaction flask and dichloromethane was added to dissolve it.…”

“…However, when performing hydro-alkylation using Et 3 Al 2 Cl 3 , the reagent needs to be operated with care since it is pyrophoric and can react violently with water. [42][43][44] Alkyl-branched fatty acids and triglycerides have displayed better oxidative stability, solubility, and viscosity which are desired properties for lubricant or biofuel applications. 20,45,46 Our earlier work on alkyl branching of beef tallow and chicken fat resulted in products with advanced oxidative stability, viscosity, and cold flow properties.…”

“…20,45,46 Our earlier work on alkyl branching of beef tallow and chicken fat resulted in products with advanced oxidative stability, viscosity, and cold flow properties. 43,44 Here, we describe the synthesis of isopropyl branched lard (BL) and the impacts of the alkyl group on its physico-chemical and tribological properties. It is expected that the results of this study will stimulate further research on the chemical modification of lard using safer and sustainable chemical reagents.…”