(408e) Comparative Evaluation of Low- and High-Temperature Friedel–Crafts Acylation Routes for Advanced Biolubricant Production

The development of sustainable and high-performance lubricants from renewable resources is critical for reducing reliance on petroleum-based products. This study presents a comparative evaluation of two advanced Friedel–Crafts (FC) acylation-based biolubricant synthesis routes using vegetable oil: a previously developed high-temperature process (FC-HT) and a novel low-temperature pathway (FC-LT).

The FC-HT route involves hydrolysis, dehydration, FC acylation, and hydrodeoxygenation (HDO) steps conducted at elevated temperatures (up to 280–350°C). In contrast, the newly developed FC-LT process significantly reduces energy requirements by integrating fatty acid chlorination, anhydride formation, and FC acylation at ≤100°C. Both processes yield biolubricants featuring unique structures composed of long-chains attached to naphthenic rings, contributing to excellent physicochemical properties.

FC-LT exhibited a kinematic viscosity of 41.6 mm²/s at 40°C, viscosity index (VI) of 151.9, Noack volatility of 5%, and a total acid number (TAN) of 11 mg KOH/g. Both biolubricants demonstrated excellent oxidative stability, as confirmed by Rotating Pressure Vessel Oxidation Test (RPVOT). Tribological testing using a Stribeck curve revealed that FC-LT exhibited a relatively lower friction coefficient trend and the lowest wear volume among all tested lubricants, including transesterified and epoxidized benchmarks.

These findings highlight the FC-LT process as a promising low-energy alternative for producing biolubricants with enhanced performance, offering a path toward scalable, sustainable lubrication technologies that meet demanding industrial specifications.