Alternative Uses for Biodiesel Byproduct: Glycerol as Source of Energy and High Valuable Chemicals

Abstract

Glycerol was firstly faced as a residue, since it is massively produced from the transesterification of vegetable oils and animal fat, corresponding to roughly 10% of the total amount of biodiesel. The recent high availability of glycerol has decreased its price and increased the risks of environmentally inadequate disposal. Now, this small chain alcohol is faced as a powerful alternative for energy conversion and production of chemicals with commercial interest. Its three hydrated carbons make this organic a noticeable substrate to produce other carbonyl compounds and to be used to produce energy in electrochemical devices collectively known as direct alcohol fuel cells. The development in the electrocatalysis field opened up new strategies to convert glycerol into power and chemicals, by using fuel cells and electrolyzer reactors. In both systems, the efficiency of the process depends on several aspects, as the medium, applied potential, and mainly on the surface reaction taking place at the interface between solution and electrode. In this chapter, we discuss the use of glycerol in these electrochemical systems and illustrate some experimental results regarding fundamental and applied science. Namely, we describe some advances in the understanding of the glycerol electro-oxidation reaction interpreted by spectroscopy and chromatographic techniques. Novel nanomaterials currently applied to improve the catalysis of the reaction are also shown. Moreover, we comment some results regarding fuel cells, microfluidic fuel cells, and electrolyzers fed by glycerol and the perspectives and challenges of its use.