Processos de oxidação e extração líquido-líquido utilizando tensoativos para remoção de enxofre do diesel

Abstract

Sulfur is one of the main contaminants of petroleum-based fuels and is present mainly in oils from mature fields, situation of most Brazilian onshore fields. The emission of sulfur in the form of SOx is generated from the burning of these fuels, such as diesel, and affects the air quality and human health. Sulfur, when present in large quantities, also promotes corrosion of engines, reducing its lifespan. In 2013, the resolution 50/2013 from ANP has adopted new specifications for diesel, becoming mandatory nationwide the commercialization of diesel (without addition of biodiesel) and B (with addition of biodiesel) containing a maximum sulfur content of 500 ppm. Therefore, the removal of sulfur has a great attention of the petrochemical industry. Solvent extraction combined with oxidative desulfurization (ECODS) is one of the most promissing techniques for sulfur heretocycles removal such as dibenzothiphene (DBT) and dimethyldibenzothiophene (DMDBT). In this context the present work studied the application of oxidative desulfurization of diesel (1200 ppm of sulfur), followed by liquidliquid extraction using non-ionic surfactants. Were obtained the parameters related to liquidliquid extraction and to the oxidation reaction using hydrogen peroxide (H2O2) and acetic acid (CH3COOH) as a catalyst. The reactional parameters of temperature, time, peroxide and acid concentrations and use of a catalyst on the reaction were evaluated using a 26-2 fractional factorial design. The sulfur concentration were reduced from 1200 ppm to 220 ppm after one oxidative desulfurization step (80 °C; 2.5 h; 700 rpm; H2O2/CH3COOH mass ratio = 0.5; H2O2/diesel mass ratio = 0.75; without solid catalyst) and one liquid-liquid extraction step using Ultranex NP110 (surfactant/diesel mass ratio = 0.5; 10 min; 25 °C). Althought for a model fuel containing 1200 ppm of DBT in n-dodecane the concentration, under the same conditions, were reduced to below 3 ppm. Therefore, the oxidation and subsequent extraction with surfactant have proven to be effective in desulfurization of diesel.