Abstract
The presence of acidic compounds as naphthenic acids in crude oil causes several problems for the petroleum industry, including corrosion in both upstream and downstream production processes. Based on this scenario, the main objective of this work was to investigate the removal of the acidic compound from two Brazilian heavy oils by adsorption processes using six potential adsorbents: powdered shale, activated carbon, bentonite, silica gel, powdered sandstone and powdered wood. These raw materials were previously characterized by conventional and surface analysis techniques, which show that they offer a good surface area and thermal stability. To evaluate the removal efficiency at the molecular level, the crude oil samples and the filtered oils were analyzed by negative electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry [ESI (-) FTICR MS]. The O2 class, which is related to the relatively high acidity of the samples, was the most abundant in both crude oil samples, moreover, this class was more retained by adsorbents. Silica gel, activated carbon and bentonite were the best adsorbents of acidic compounds from the tested oils, in agreement with their markedly higher surface area and porous volume. Additionally, a chromatographic analysis was performed and showed no changes in the oil profile.
Highlights
The mixture of many hydrocarbon compounds, nonhydrocarbon compounds containing heteroatoms, and metallic compounds makes the petroleum matrix quite complex
This study aims to evaluate the efficacy of six potential adsorbents (powder shale, activated carbon, bentonite, silica gel, sandstone and wood powder) to remove acidic polar compounds, especially naphthenic acids, from Brazilian heavy crude oils
The results show that relative abundance of filtered oils is lower than crude oil abundance, it is indicating which the naphthenic acids (NA) compounds were adsorbed along with all DBE range, for C13 and C20 samples, there is a highlight for some adsorbents
Summary
The mixture of many hydrocarbon compounds, nonhydrocarbon compounds containing heteroatoms, and metallic compounds (mainly nickel and vanadium) makes the petroleum matrix quite complex. Brazil has a diversified petroleum production from onshore and offshore fields and produces asphaltic oil, such as Hárpia (Sergipe e Alagoas Basin) and Fazenda Alegre (Espírito Santo Basin), with an API gravity of 13.3, to super-light oil, such as Condensado de Merluza (Santos Basin), with an API gravity of 57.7 (ANP 2019). These differences represent a heterogeneous quality in the produced oil. This diversification in petroleum composition directly impacts all refinery processes, and compositional information is vital for advances in effective petrochemical processing (Rodgers et al 2002)
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