Valorização sustentável dos resíduos do óleo de candeia por hidrogenação catalítica

Abstract

This study aims to transform a residue from the candeia (Eremanthus erythropappus (DC) MacLeish), applying circular economy concepts in the production chain through the use of heterogeneous catalysis in hydrogenation processes. The residue provided by the company Citróleo, was characterized using chromatography, infrared, and nuclear magnetic resonance techniques, identifying non-oxygenated sesquiterpenes, α-bisabolol, and methyl eugenol in its composition. An attempt was made to fractionate this residue through column chromatography and liquid-liquid extraction, generating a polar and an apolar fraction for each extraction method, and the effectiveness of each was evaluated. The mixture of compounds was subjected to hydrogenation processes using a commercial palladium catalyst supported on activated carbon, where parameters such as temperature, catalyst mass, reaction time, and hydrogen pressure were evaluated. In a typical reaction were used 2 mL of the residue 100 °C, 25 mg of catalyst, 20 hours of reaction, and 10 atm of hydrogen, without the need for solvent. Under these conditions, high conversions (98%) and selectivity for alkanes, aromatic hydrocarbons, and oxygenated compounds were obtained, at 49, 12, and 19%, respectively. The hydrogenation product was fractionated in the same way as the initial substrate, and cytotoxicity tests were performed. It is noted that after the hydrogenation process, the candeia terpene loses the cytotoxicity observed at a concentration of 51,9 mg mL-1 and no longer exhibits toxicity at the tested concentrations.