Elizabeth M. Moreira

Ultrasound-assisted oxidative process for sulfur removal from petroleum product feedstock

A procedure using ultrasonic irradiation is proposed for sulfur removal of a petroleum product feedstock. The procedure involves the combination of a peroxyacid and ultrasound-assisted treatment in order to comply with the required sulfur content recommended by the current regulations for fuels. The ultrasound-assisted oxidative desulfurization (UAOD) process was applied to a petroleum product feedstock using dibenzothiophene as a model sulfur compound. The influence of ultrasonic irradiation time, oxidizing reagents amount, kind of solvent for the extraction step and kind of organic acid were investigated. The use of ultrasonic irradiation allowed higher efficiency for sulfur removal in comparison to experiments performed without its application, under the same reactional conditions. Using the optimized conditions for UAOD, the sulfur removal was about 95% after 9min of ultrasonic irradiation (20kHz, 750W, run at 40%), using hydrogen peroxide and acetic acid, followed by extraction with methanol.

Determination of Sulfur in Petroleum Coke Combining Closed Vessel Microwave-Induced Combustion and Inductively Coupled Plasma-Optical Emission Spectrometry

Abstract A new procedure based on closed vessel Microwave-Induced Combustion (MIC) technique is proposed for the decomposition of petroleum coke and further determination of sulfur by Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). The procedure is based on sample ignition by microwave radiation using closed quartz vessels pressurized with oxygen and use of NH4NO3 as an ignition aid. The nature and concentration of absorbing/refluxing solution were studied, as well as the operational parameters related to MIC technique. Results were compared with those obtained by conventional wet digestion in closed vessels, certified reference materials (agreement was better than 98%), and also using ion chromatography for S determination.

Fuel desulfurization/denitrification via adsorption or extraction: A complementary approach to oxidative treatments

ABSTRACT Strict rules and environmental concerns make the production of clean fuels that display very low sulfur (S) content mandatory for the petroleum refining industry. In parallel, nitrogenated compounds present in feedstock are deleterious for the various processes in a refinery. Herein, diesel oil desulfurization and denitrification via adsorption or extraction have been investigated as sequential and complementary treatments to oxidative protocols. Diesel fuel (S = 231 ppm and N = 115 ppm) has been treated with a number of adsorbents (including commercial silica gel and Fuller’s Earth powder) at room temperature in fixed-bed cartridges. Comparisons with typical extraction procedures showed that processes with suitable adsorption agents were more efficient in terms of both residual S/N content and fuel mass balance. These simple adsorption methods can be applied to any refining process as pre- or post-treatment. The application of these methods in oxidative diesel desulfurization/denitrification has been found to be particularly beneficial.