Oil-Based Second Generation Biorefineries

S. PEREDA; N. COTABARREN; G. SOTO; P. HEGEL

York

Conferencia; 11th International Conference on Renewable Resources and Biorefineries; 2015

University of York

Second generation oil-based biorefineries are aimed not only to recycle used cooking oil, but also to enrich any residue with oil content. For example, the great increase of worldwide production of soybean and sunflower oil, impacted not only in the oil market but also in the oil refining by-products (phospholipids sludge and distillates of the deodorizer), which prices are rapidly changing. Even though these residues contain high-added value products, their cost are decreasing, becoming sometimes a waste with disposal-associated problems. Furthermore, sludge processing to recover oil or phospholipids is complex. Because of its high viscosity and poor flow properties (sticky behavior), its processing needs large volumes of solvent. Thus, in addition to being costly, it has a high environmental impact. An alternative sustainable technology is the direct alcoholysis of phospholipids and vegetable oil (triglycerides) occluded in the wet gum using supercritical ethanol to produce fatty acids ethyl esters (FAEE). On the other hand, acylglycerols are high added-value products derived from vegetable oil. They are common food emulsifiers and surface active agents in many industrial cleaning products. Commercial MG is obtained via an alcoholysis pathway in which either fatty acids or a fat are reacted with an excess of glycerol. The reaction products contain mainly mono-, di-, tri-glycerides (MG, DG, TG, respectively) and glycerol, but depending on the glycerol/fat ratio the MG composition fluctuates between 40 and 60% of MG. A further refined MG up to around 90 wt% purity, also called high mono, is conventionally obtained by short path distillation of the reaction products at ca. 473 K and 0.01 mbar or less. This process is expensive and recovers only part of the produced MGs, in addition high purity cannot be reached due to thermal degradation of products and raw materials. An alternative pathway of synthesis is needed to improve the atomic efficiency of the purification process. Acylglycerols can be economically produced in biodiesel processing plants, carrying out an incomplete transesterification of vegetable oil. Moreover, the purification of MG from a mixture of biodiesel can be carried out with pure CO2 as a green solvent. In this presentation, sustainable technologies for residues processing and vegetable oil recycling will be discussed. Moreover, also a high pressure technology for high purity monoglycerides recovery will be presented. Integration of the discussed technologies may contribute to pave the way towards oil-based second generation biorefinery development.