Catalytic conversion of glycerol. A review of process kinetics and catalytic reactors

Glycerol, the by-product of the Biodiesel manufacturing from vegetal and animal fats, is an important bio-resource, which can be transformed into a significant number of valuable products, by catalytic, enzymatic, or biological technologies. This paper presents a review of published studies on the kinetics of the main catalytic transformations of glycerol into valuable products, along with information regarding the catalytic reactors experienced or proposed for these transformations. In the kinetic description of the glycerol catalytic transformations, the most used are the rate expressions based on the Langmuir-Hinshelwood-Hougen-Watson (LHHW) theory and the empirical ones, of the power law type. The published results are evidencing that, in addition to the general technical and economic advantages, the liquid phase continuous processes of glycerol transformation are more efficient, ensuring, in many cases, a higher selectivity of the transformation and a slower deactivation of the catalyst.