Controlling the oxidative stability of biodiesel using oils or biodiesel blending or antioxidants addition

Abstract

Among the 25 parameters established by the European Standard (EN14214:2012) to certify the quality of biodiesel, the oxidative stability is of concern, particularly when storing biodiesel for long periods. The products of biodiesel degradation are corrosive and lead to the formation of engine deposits that can block the filters and fuel injectors. Thus, EN14214:2012 establishes a period of 8 h for the oxidative stability of biodiesel. The main goal of this work is to study the effect of storage conditions in the oxidative stability of biodiesel and to understand how to control this property on the different stages of biodiesel production, namely through: (1) the use of different raw‐materials, blending, and production strategies; (2) the addition of antioxidants. NIR spectroscopy was used to follow the transesterification reaction and to analyze the different biodiesel samples. The storage conditions, such as sunlight exposure, temperature and presence of air, have a great impact on the oxidative degradation of biodiesel. Actually, for example, a decrease in 50% of the oxidative stability was obtained after less than 20 days of storage in an opaque plastic bottle. On the other hand, the addition of 20% (w/w) of palm oil to rapeseed or soybean oils allows to increase the oxidative stability by 1 h and the addition of palm biodiesel to rapeseed or soy biodiesel has a similar effect. Hydroquinone showed to be a very effective antioxidant. In fact, the addition of 114 mg/kg lead to an increase in the induction period of soybean biodiesel of more than 4 hours, whereas 65 mg/kg is sufficient to reach the 8h established in the European Norm. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 1031–1040, 2018

Safflower Biodiesel: Improvement of its Oxidative Stability by Using BHA and TBHQ

“…Consequently, the use of this pure biodiesel would not be possible, and a mixture with other biodiesel or the addition of antioxidants was required. Nonetheless, the abovementioned results are usual for biodiesel samples made by other authors, showing a similar behavior, that is, high flash and combustion points and short oxidative stabilities (from 2 to 6 h, depending on the raw material) [40,50]. Specifically, the results found for safflower biodiesel were similar to those found in the literature by other authors, although, there were some discrepancies (viscosity and density were slightly higher in some cases, for instance).…”

“…Consequently, the mixture with other more stable biodiesel [40], the use of antioxidants (both natural and artificial) [41][42][43][44][45], and other chemical reactions [34] have been attempted in order to increase the oxidative stability of biodiesel samples, to revalue this product. Although the raw material usually contains natural antioxidants, during biodiesel production and purification they are usually missed.…”

“…Moreover, the use of antioxidants could contribute to keep biodiesel from increasing NO x emissions during combustion in diesel engines [38]. Although in some cases the combined use of antioxidants in biodiesel has been studied, there are controversial results about their synergetic or additive effect, depending on factors such as the raw material used [37,40,43,50,51]. In the case of safflower biodiesel, no studies about the improvement of its oxidative stability were found, making the compliment of this requirement an important aspect for the valorization of this biofuel.…”

Optimización y caracterización física del biodiesel obtenido del aceite de residuos de Annona cherimola

“…Actualmente, las necesidades de combustibles se han incrementado considerablemente, así como la dependencia del uso de combustibles fósiles, que conlleva a problemas políticos y medio ambientales [6]. Por lo tanto, la conciencia general sobre las energías renovables, con un menor impacto ambiental, ha aumentado y el biodiesel de primera generación es la alternativa actualmente disponible al diésel fósil [7].…”

The technical and economic evaluation of biodiesel production processes from different vegetable oils

“…Biodiesel is a fuel consisting of mono‐alkyl fatty acid esters derived from natural sources 1‐5 . These sources are vegetable oils (soybean oil, rapeseed, cotton, castor oil, mustard, etc.)…”