Esterification of free fatty acids in waste cooking oils (WCO): Role of ion-exchange resins

Synthesis of bio-additives: transesterification of ethyl acetate with glycerol using homogeneous or heterogeneous acid catalysts

“…Usually, academic studies on its catalytic activity do not employ the resin in its wet form and water removal before using is performed. 16,38,39 Amberlyst-15…”

Comparison of Novozyme 435 and Purolite D5081 as heterogeneous catalysts for the pretreatment of used cooking oil for biodiesel production

“…UCO is a waste material and this means that it is possible to reduce the amount of waste going to landfill and use a relatively cheap material. UCO contains free fatty acids (FFAs), which form due to hydrolysis of triglycerides during cooking [12] and this results in a saponification side reaction during transesterification, when a base catalyst is used [13]. The saponification reaction consumes the catalyst and can form an emulsion which makes separating the products difficult and reduces biodiesel yield [5].…”

“…Currently most esterification processes use homogeneous catalysts such as sulfuric or sulfonic acid [5,14], however, homogenous catalysts are difficult to separate from the products, generate large amounts of waste water, and require expensive materials to prevent associated corrosion [15]. As a result solid acid catalysts such as ionexchange resins have been investigated as heterogeneous esterification catalysts with high FFA conversions reported [12,16,17]. Acid catalysts can also be used for transesterification, however, the reaction rate is much slower [10].…”

Pretreatment of Used Cooking Oil for the Preparation of Biodiesel Using Heterogeneous Catalysis

“…The most common process for making biodiesel is the transesterification of vegetable oils with methanol, in the presence of alkaline catalysts to form fatty acid methyl esters (FAME) which is the biodiesel product, a schematic representation of the reaction is shown in Figure 1. Vegetable oil is an expensive raw material and as a result alternatives have been investigated and these include non-edible oils such as Jatropha Curacas, by-products from oil refining such as palm fatty acid distillate, animal fats, algal oil and used cooking oil (UCO) [1][2][3] Figure 1: Schematic representation of the transesterification reaction UCO contains free fatty acids (FFAs), which form during cooking [4] and these need to be removed prior to transesterification. Esterification can be used to convert the FFAs to biodiesel [1] and a schematic of this reaction is shown in Figure 2.…”