Biolubricants Based on Vegetable Oils

For a better understanding of the subject of this book, it is important to introduce some interesting concepts, as well as the main events taking place in history for the development of lubricants and biolubricants. At the end of this chapter, the main reasons to use biolubricants will be discussed.

In this chapter, the main advantages and disadvantages related to the production and use of biolubricants are discussed, having to do with environmental aspects as well as the good lubricating performance of these products.

In this book chapter, the main raw materials for biolubricant production are covered, focusing on vegetable oils and the most representative waste obtained from them: waste cooking oil. Their origin, composition and characteristics will be discussed, which is essential to understand the properties of the subsequent biolubricants and the right selection of the corresponding synthesis method.

This chapter is devoted to answering one of the main questions about biolubricants: how are they produced? Surprisingly enough, there is not one single way to produce biolubricants, as there are plenty of chemical routes for this purpose. As you can imagine, each chemical route has its pros and cons, but on the whole, they offer a wide range of products with different properties (with viscosity as the main property for specific lubricating processes).

This chapter will deal about the assessment of the main properties of a biolubricant. There are plenty of characteristics that a certain biolubricant should comply with to compete with petroleum-based lubricants. In that sense, the role of viscosity or oxidation stability, among others, will be important for their suitability of use. Once the main chemical routes to produce and purify biolubricants have been explained in previous chapters, it is necessary to assess their main physical and chemical properties, which will determine their final usage. As you can imagine, every product that you purchase as a consumer (from potato chips to a van, for instance) has to comply with strict standards to be commercialized, so that these products can be safe or have minimum quality standards. Regarding biolubricants, they are no exception and some properties such as viscosity or oxidative stability (which should be familiar to you at this point) are perfectly analyzed to check if they are suitable for lubricating purposes. Thus, every aspect of these products should be covered, from ecotoxicity to skin irritability or viscosity index. Even though we found these standards strict or confusing sometimes, there is always a good reason to establish a lower or upper limit. For instance, viscosity is essential to carry out a good lubricating effect depending on the kind of surfaces in contact, temperature, etc. Also, viscosity in biodiesel (one of the intermediate products during double transesterification to produce biolubricants) is important in diesel engines, as it is essential to inject the fuel properly in the combustion chamber.

This chapter will cover the main uses of biolubricants according to different standards, as well as new research lines devoted to the improvement of their characteristics, production or final performance. Thus, some aspects such as the improvement of oxidative stability, the development of new heterogeneous catalysts or the real implementation of biolubricant production at industrial scale will be trending topics in future research.

As inferred from previous chapters, many conclusions can be drawn when it comes to biolubricant production and characterization. After reviewing a considerable amount of the abundant research carried out in the last two decades, a wide variety of specific conclusions about biolubricant production, characterization or optimization could be drawn. However, from our point of view, there are some patterns or points in common on the whole, which could clarify many questions or concerns about this subject.