Carbon black-2,2’-bipyridine-ruthenium composite catalyst for the oxidative cleavage of oleic acid

Details

Supervisors

Gaigneaux, Eric M. ; Gamez Rivera, Sebastian Antonio

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en chimie et bioindustries, à finalité spécialisée

Abstract

It is well-known that petrochemical molecules will one day run out. Not only they are finite and increasingly scarce, but also polluting. Nevertheless, petrochemicals are platform molecules, used in the synthesis of important products such as polymers, detergents, organic solvents, etc. Consequently, it is very important to find new renewable and eco-friendly molecules from which the same products can be synthesized. One alternative might be the transformation of vegetable oils and animal fats into value-added molecules. This process is called oleochemistry. Lipids have the advantage of being abundant, biodegradable and do not contain toxic elements as in petrochemicals, which makes them friendly with the environment. Triglycerides are well-known lipids produced by the esterification of glycerol which can be easily hydrolysed into fatty acids (FA), those one being either saturated (without C=C bond) or unsaturated (with C=C bond(s)). Oleic acid (OA) is the most abundant mono-unsaturated fatty acid (UFA) on Earth and is industrially used for the production of pelargonic and azelaic acids (PA & AA). PA and AA, which are mono- and dicarboxylic acids with an odd number of carbon atoms, are used in different applications. For instance, AA is industrially transformed for the production of polyamides (e.g. nylon 6:9), polyesters and polyurethane or is used as an anti-inflammatory and acne medicine. PA is used in the production of herbicides, fungicides and resins. The conventional process to obtain PA and AA involves the oxidative cleavage of the C=C bond with O3 (a hazardous and toxic compound) as oxidizing agent. The use of this oxygen allotrope limits the scope of substrates that can be used and constrained the scale-up of this process. As alternatives, heterogeneous catalysts were poorly studied, especially for the oxidative cleavage of UFAs. In this work, we focused on a Ru-based heterogeneous catalyst. Indeed, Ru under its tetroxide form is well known to perform the oxidative cleavage of OA into PA and AA with ease, at room temperature and atmospheric pressure. Thus, using the cheap carbon black (CB) as support, we tried to enhance the affinity of CB with Ru using an anchored 2,2’-bipyridine ligand at its priorly oxidized surface. The best catalyst stayed above 70% conversion during 5 recycle runs and had high selectivity towards PA and AA. However, leaching of Ru species was still observed, leading to the deactivation of the catalyst. Therefore, further research to enhance the affinity of RuO4 to CB without reducing its activity must be done.