Improving the low‐temperature properties of alternative diesel fuels: Vegetable oil‐derived methyl esters

Abstract

This work explores near-term approaches for improving the low-temperature properties of triglyceride oil-derived fuels for direct-injection compression-ignition (diesel) engines. Methyl esters from transesterified soybean oil were evaluated as a neat fuel and in blends with petroleum middle distil~ates. Winterization showed that the cloud point (CP) of methyl soyate may be reduced to -I 6~ Twelve cold-flow additives marketed for distillates were tested by standard petroleum methodologies, including CP, pour point (PP), kinematic viscosity, cold filter plugging point (CFPP), and low-temperature flow test (LTFT). Results showed that additive treatment significantly improves the PP of distillate/methyl ester blends; however, additives do not greatly affect CP or viscosity. Both CFPP and LTFT were nearly linear functions of CP, a result that compares well with earlier studies with untreated distillate/methyl ester blends. In particular, additives proved capable of reducing LTFT of neat methyl esters by 5-6~ This work supports earlier research on the low-temperature properties; that is, approaches for improving the cold flow of methyl ester-based diesel fuels should continue to focus on reducing CP. JAOCS 73, 1719-1728 (]996).

Adsorption in Biodiesel Refining - A Review

“…(ii) Winterization for removing the waxy saturated fraction also removes the fraction with higher cetane and oxidizing stability. (iii) Commercial pour point depressants are reported to reduce the pour point of biodiesel but usually do not reduce its cloud point nor improve its filterability at low temperatures (Dunn et al, 1996). Fortunately, biodiesel-petrodiesel blends have cloud and pour points closer to those of petrodiesel.…”

Effects of different chemical additives on biodiesel fuel properties and engine performance. A comparison review

“…Blending with petroleum diesel is only effective at low biodiesel proportions (up to 30% by vol.) with cloud points to around -10 o C [23]. Clearly, blends with petroleum diesel do not change the chemical nature and therefore the properties of biodiesel will not facilitate their use at higher concentrations.…”

“…These solid crystals may cause start up problems such as filter clogging when ambient temperatures drop to around -10 to -15 o C [21]. While the cloud point of petroleum diesel is reported as -16 o C, biodiesel typically has a cloud point of around 0 o C, thereby limiting its use to ambient temperatures above freezing [22,23].…”

Síntesis de Aditivos para Biodiesel a partir de Modificaciones Químicas de la Glicerina

“…El biodiesel en general comparado con el diesel de petróleo cumple con la mayoría de propiedades fisicoquímicas de este combustible, sin embargo, en lo que se refiere a las propiedades de flujo a baja temperatura (PFBT), presenta valores inferiores, lo que constituye el principal problema para su uso en regiones y en épocas donde la temperatura del ambiente es baja (Knothe et al, 2005;Schumacher et al, 1999). Esto se debe principalmente al tipo de materia prima que se emplee, así, el biodiesel derivado de aceites vegetales compuesto por ácidos grasos saturados presentan los más altos puntos de nube y fluidez (Dunn et al, 1996). El biodiesel de aceite de palma contiene 51.51% de metilésteres de ácidos grasos saturados mostrando las más deficientes PFBT en comparación con el biodiesel derivado de otros aceites (Fangrui y Milford, 1999;Mihara et al, 2006;Ali et al, 1995).…”

“…Tabla 1: PBFT de varios alquilésteres de aceites vegetales (Knothe et al, 2005) Aceite/Alcohol Viscosidad (cP) Se han reportado diferentes estrategias para mejorar las PFBT dentro de las que se destacan: (i) mezcla en bajas proporciones con diesel (Knothe et al, 2005;Rushang y Michael, 2007;Dunn y Bagby, 1995); (ii) empleo de aditivos derivados de alcoholes ramificados o de mayor longitud de cadena (Lee et al, 1995;Rodríguez et al, 2006;Moser y Erhan, 2008); (iii) empleo de la winterización (Dunn et al, 1996;Lee et al, 1996;González et al, 2002); (iv) empleo de aditivos formulados para mejorar las PFBT de combustibles (Schumacher et al, 1999;Bashkatova, 2001); (v) mezcla de biodiesel de diferentes aceites vegetales (Park et al, 2007) y (vi) empleo de aditivos del tipo acetales, cetales y acetatos (Delgado, 2004;Filley, 2004;Delgado, 2008;Bradin, 2007). Los acetales y cetales son compuestos útiles para los combustibles, en tanto que mejoran sus propiedades de combustión ya que son compuestos oxigenados, lo que disminuye las emisiones y mejora las PFBT (Filley, 2004;Noureddini, 2000).…”