Advancements in solid acid catalysts for ecofriendly and economically viable synthesis of biodiesel

Abstract

Solid acid (heterogeneous) catalysts have a unique advantage in esterifi cation and transesterifi cation reactions which enhances the use of high acid value oil to be used as feedstock for synthesis of biodiesel. Various solid acid catalysts such as resins, tungstated and sulfated zirconia, polyaniline sulfate, heteropolyacid, metal complexes, sulfated tin oxide, zeolite, acidic ionic liquid, and others have been explored as potential heterogeneous catalysts.The activity of the catalyst differs slightly resulting in moderate to high conversion and yield. The reuse of the solid catalyst is governed by their deactivation, poisoning, and the extent of leaching in the reaction medium. The applicability of these catalysts for synthesis of biodiesel along with their reusability aspect is discussed in this review.

Conversion of by-products from the vegetable oil industry into biodiesel and its use in internal combustion engines: a review

“…The development of heterogeneous catalysts has been a relatively recent area of research in the synthesis of biodiesel (Sharma et al, 2011;Trakarnpruk, 2012). Their use has a great potential not only technologically but also economically (Marchetti, 2012;Joon et al, 2011).…”

“…Reuse of the catalyst is another advantage (Sharma et al, 2011;Oliveira et al, 2010;Bournay et al, 2005;Jiang et al, 2010). They are categorized as solid acid and solid base catalysts.…”

Non Edible Oils: Raw Materials for Sustainable Biodiesel

“…This method is particularly convenient as it is not only able to lower the acidity content of the oils but also provides methyl esters already at this stage, so increasing the final yield in biodiesel. A scheme of the FFA esterification reaction is given in Fig.2 The use of heterogeneous catalysts (Sharma & Singh, 2011) is usually preferred to the use of homogeneous ones (Alsalme et al, 2008) as it prevents neutralization and separation costs, besides being not corrosive, so avoiding the use of expensive construction materials. Another important advantage is that the recovered catalysts can be potentially used for a long time and/or multiple reaction cycles.…”

Transesterification of Waste Cooking Oil to Biodiesel over Calcined Hydroxy Sodalite (HS) Catalyst: A preliminary investigation

“…Consequently, Biodiesel from high FFA content feedstock is conventionally produced by a two-stage process: esterification, followed by transesterification [8]. The esterification step serves to reduce the amount of FFAs present in the oil in order to allow for the transesterification reaction to commence [9]. The implication of this additional process unit is inevitably the additional costs associated with the biodiesel production.…”