Abstract Biodiesel is a standout renewable fuel in the global energy matrix transition process, but it still faces persistent durability and stability issues. Hence, it is crucial to develop and apply additive-based chemical technologies that can maintain physicochemical properties, such as oxidative stability and low corrosivity, or mitigate issues, such as low fluidity and crystallization. Despite their established synthetic accessibility, few studies have specifically evaluated fatty acid amides (FAAs) as additives for fuel applications. In the present work, we synthesized a set of FAAs under solvent-free conditions via DBU-promoted aminolysis of fatty acid methyl esters (FAMEs), with cyclic and acyclic amines, and assessed their antioxidant activities, cold-filter-plugging-point (CFPP) properties, and corrosion-inhibition effects, aiming to evaluate their applicability as potential biodiesel additives. The FAAs ( 3a-h ) were obtained in good-to-excellent yields (65–92%) and characterized through GC-MS, FT-IR methods, and/or 1D NMR ( 1 H and 13 C) spectroscopy techniques. All FAAs revealed no pronounced antioxidant capacity against the Rancimat method. On the other hand, stearamides 3a , 3c , and 3e at 0.2% (w/w) in soybean biodiesel allowed a decrease in the CFPP of biodiesel between 4 and 6 °C. In addition, the immersion test of soybean biodiesel blended with FAAs 3b , 3c , and 3 h showed corrosion inhibition efficacy of over 50% and significantly reduced the corrosion rate of the zinc coating compared to pure biodiesel. Taken together, these findings indicate that FAAs derivatives represent a promising technological option for modulating the physicochemical properties of biodiesel fuel. Graphical Abstract Solvent-free synthesis of fatty acid amides as multifunctional biodiesel additives improving cold-flow and corrosion resistance.
Meira et al. (Tue,) studied this question.