Use of mild reaction conditions to improve quality parameters and sustainability during biolubricant production

The use of alternative sources to produce less pollutant biofuels and biomaterials, replacing petroleum-derived products, is becoming an important issue for international organizations, governments, and society. Thus, biodiesel and biolubricant production has been increasingly researched, offering promising results. These products present some advantages such as sustainability or biodegradability, among others. However, some of their quality parameters can be altered during storage, mainly due to their low oxidative stability. Consequently, auto-oxidation processes can take place, increasing viscosity or acid number, which can compromise their marketability. To avoid these inconveniences, some alternatives have been presented, such as the use of antioxidants, vegetable oil selection or the promotion of mild chemical conditions during production. The aim of this work was to assess the use of vacuum during biolubricant production from high-oleic safflower oil through double transesterification with methanol and 2-ethyl-2-(hydroxymethyl)-1,3-propanediol to obtain mild chemical conditions. Under these circumstances (working pressure at 210 mmHg) and compared to previous studies, temperature and catalyst addition could be reduced from 140 to 100 °C and from 0.5 to 0.3%, respectively, increasing the reaction yield from 92.9 to 94.69% and improving the quality of the biolubricant, with 30% increase in viscosity index. [Display omitted] •The effect of vacuum on biolubricant production and its properties is covered.•Lower temperature and catalyst addition were used thanks to vacuum.•Higher yields were obtained compared to previous studies.•Better properties (including oxidative stability) were found.