Caracterização química e avaliação da atividade interfacial de frações isoladas de petróleos brasileiros pelo método da sílica molhada

Abstract

This work presents a study of the fraction of petroleum molecules of greater affinity with a water / oil interface, isolated from the wet silica method, based on the adsorption capacity of the molecules onto silica water surface. Isolation was carried out from cyclohexane / toluene dispersions of two samples of Brazilian oils (named in this Thesis P5 and P6) and of maltenic and asphaltenic fractions (extracted from P6 oil), obtaining, for each sample, a fraction of molecules interfacially active (IA) and a fraction of non-interfacially active molecules (NIA). In addition, for P6 oil, the procedure was also performed using octane / toluene as solvent. All samples were characterized by FTIR, 1H-NMR and ESI (±) FT-ICR MS and analyzed for interfacial activity, using brine as the aqueous phase and dispersions in n-heptane / toluene mixtures as the organic phase. It was possible to conclude that the fractions IA-P5 and IA-P6 differ, mainly, in the classes of acidic compounds, which adsorb primarily onto aqueous surface. For the IA’s fractions isolated from the same oil (P6) with different solvents, the influence of the solvent system was observed only on the basic species that adsorb onto outermost layers of the interfacial film. The comparison of the IA-P6 fraction with the IA-M and IA-A fractions, obtained from maltenes and asphaltenes, indicates the presence of classes of compounds from both maltenes and asphaltenes at the water / oil interface, as opposed to the idea that asphaltenes are responsible for stabilizing oil emulsions.