Síntese e caracterização de catalisador heterogêneo a base de carbono sulfonado aplicado na reação de esterificação

Abstract

The consumption of fossil fuels derived from petroleum has a significant impact on the environment, as a consequence, the demand for fuels that have a lower environmental impact, such as biodiesel, has increased. In the industry it is very common to use homogeneous catalysis to obtain bioproducts, but even with a high yield, this process offers disadvantages due to subsequent separation and neutralization steps. Because of this, the heterogeneous catalysts appear as solution to the problem, allowing the reuse of the catalyst too. Therefore, the objective of the work was to synthesize heterogeneous catalysts using commercial activated carbon (CA), Norit GAC 1240 PLUS, as raw material. The carbons were chemically modified to obtain materials with sulphonic groups (-SO3H) on their surface, and thus to produce catalysts with excellent catalytic stability and activity. These materials were sulfonated with sulfuric acid (98%) at different temperatures (150°C and 200°C), being produced by a reaction system in reflux. After the synthesis of these catalysts, analyzes were carried out in order to verify the modification of the surface area of the material, as well as the presence of the sulphonic groups in the activated carbon. Finally, the synthesized catalysts were applied in esterification reactions, and the products obtained were physicochemically characterized by: acidity index, specific mass at 20°C and kinematic viscosity at 40°C and 100°C. After the analysis, it was possible to observe by the FTIR method and by the nitrogen adsorption measurements at 77 K that the sulfonic groups were present in the activated carbon. In addition, it was obtained bioproducts with high conversion (97.04 - 98.98%) and physical-chemical characteristics similar to bioproducts from the esterification reaction of oleic acid and alcohol (octanol and 2- ethylhexanol) in the presence of Amberlyst-15. In view of this, it can be concluded that the application of sulfonated activated carbon in esterification reactions is quite promising.