Antioxidants for biodiesel: Additives prepared from extracted fractions of bio-oil

Abstract

Unlike petroleum diesel, the chemical structure of biodiesel makes it prone to oxidation during long-term storage, thus involving fuel quality deterioration. Therefore, the addition of antioxidants is usually required to meet the quality standards for biodiesel commercialization. Synthetic sterically-hindered phenols have been usually employed for this purpose as free radical scavenging antioxidants. However, naturally occurring phenolics are also available, for example, in the bio-oil produced in the pyrolysis of lignocellulosic biomass. In this work, the antioxidant potential of extracted fractions of lignocellulosic bio-oil has been evaluated. Different organic solvents were tested as extraction agents, acetate esters being the best ones for incorporating bio-oil antioxidant compounds into biodiesel. In the best case, the incorporation of a small concentration of bio-oil compounds (< 4 wt. %) led to an improvement of the biodiesel oxidation stability of 475 % which, in our case, was enough to meet the European standard requirement.

Performance and emissions of a diesel engine using sunflower biodiesel with a renewable antioxidant additive from bio-oil

“…The mixture was heated up to 60 °C for 3 h at atmospheric pressure and continuously stirred in a batch reactor under reflux. More details about the preparation method can be found elsewhere [23]. Several batches of biodiesel were prepared to get the amount needed for this work, around 25 L. After preparation, all the biodiesel batches were mixed and kept at −18 °C until its utilization.…”

“…The final additive was mainly composed of biodiesel, with a concentration higher than 80%. More details about the preparation method can be found in the work by García et al [23].…”

“…Prior to the engine tests, the six fuels were characterized using several analytical methods that are listed in Table 1. Sample preparation procedure and parameters for the analysis method are described elsewhere [23]. Two or three replicates of each property analysis were conducted.…”

“…For instance, García-Pérez et al [8] added bio-oil to biodiesel and observed an increase in the oxidation induction temperature from 155 to 225 °C, attributed to the presence of antioxidant compounds in the bio-oil. In a previous work of our research group [23], an antioxidant additive was produced by two-stage liquid-liquid extraction of bio-oil coming from pinewood pyrolysis with different organic solvents and biodiesel itself. Sunflower oil biodiesel was treated with the obtained additives.…”

Using Canola Oil Biodiesel as an Alternative Fuel in Diesel Engines: A Review

“…The effect of auto-oxidation was greater than that of photo-oxidation. The use of antioxidants [76], or the combination of biodiesel and diesel fuel, is an important way to improve the oxidation stability of biodiesel. Focke et al [77] have found that phenolic (DTBHQ) and phosphite (Naugard P) antioxidants can improve the antioxidant properties of COB fuel.…”