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ESTUDIO DE LA ADSORCIÓN DE ASFALTENOS Y DE SUS SUBFRACCIONES A1 Y A2 SOBRE NANOPARTÍCULAS DE SIO2 MEDIANTE TÉCNICAS METALOPETROLÓMICAS

Abstract : Thanks to numerous investigations in the oil industry, the fractions with the highest added value (saturates, aromatics and resins) and the fraction responsible for the problems during production, transport, and refining have been identified. The latter corresponds to asphaltenes, which show a tendency to adsorb on surfaces and aggregate, leading to flocculation and precipitation. To minimize the adverse effects, different strategies have been developed, some of them involving large investments. For this reason, research continues to be carried out where it is necessary to know the structure or fraction of the asphaltenes responsible for this instability. For its study and due to its complexity, asphaltene separation techniques are proposed, among them the fractionation by complex formation with p-nitrophenol, which generates two subfractions called A1 (insoluble in toluene) and A2 (soluble in toluene).In the first stage, the present doctoral thesis work aims to study the aggregation behavior of the asphaltenes and compare it with that of their A1 and A2 subfractions. For this purpose, asphaltenes were obtained from three samples of Venezuelan curds: Hamaca, Cerro Negro, and Furrial, and then their A1 and A2 subfractions were obtained by complex formation with p-nitrophenol. From GPC-ICP HR MS molecular weight distribution profiles of vanadium, sulfur, and nickel, the chromatograms showed the presence of four regions depending on the hydrodynamic volume of the components: aggregate cluster region or SHMW, high molecular weight or HMW, medium molecular weight or MMW, low molecular weight or LMW. The results in THF solutions showed that subfraction A2 presented higher intensity for the three isotopes studied in the conglomerate region compared to asphaltene and subfraction A1. While in CHCl3, a marked shift towards the SHMW region was evidenced, which is attributed to the fact that in CHCl3 the formation of aggregates persists, compared to THF, which is a better solvent for the more polar fractions.By the above and making use of its ability to adsorb on different surfaces, the adsorption of asphaltenes on SiO2 nanoparticles has been studied because of its interest as a strategy to mitigate the adverse effects in the oil industry. For this reason, in a second stage, the present work proposed to study the adsorption of asphaltenes and their subfractions A1 and A2 on SiO2 nanoparticles as a strategy to evaluate the influence of this adsorbent on the aggregation process.The SiO2 nanoparticles were obtained from rice husks to avoid the synthesis by Stober's method. Once the starting materials were obtained, adsorption experiments were carried out on the nanoparticles at 3 % w/v for 72 h, in toluene (as preliminary tests of the behavior of the asphaltenes), in THF and CHCl3, where comparisons could be made between the behavior of the asphaltenes and their A1 and A2 subfractions. The solutions before adsorption (original), after adsorption (remanent), and an extract made with THF (extract) were analyzed by GPC-ICP HR MS. The analysis of the chromatograms of the remaining solutions after adsorption on SiO2 nanoparticles showed the effect of the solvent on the adsorption process, the better its ability to stabilize the components in solution, the less interaction they may have with the adsorbent surface. Thus, in THF there is no tendency for adsorption on the surface, while in CHCl3 the nanoparticles retain the SHMW and HMMW components which are the main contributors to the adsorption process.
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Submitted on : Friday, November 26, 2021 - 11:23:10 AM
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Genesis Gonzalez Contreras. ESTUDIO DE LA ADSORCIÓN DE ASFALTENOS Y DE SUS SUBFRACCIONES A1 Y A2 SOBRE NANOPARTÍCULAS DE SIO2 MEDIANTE TÉCNICAS METALOPETROLÓMICAS. Chemical engineering. Université de Pau et des Pays de l'Adour; Universidad central de Venezuela. Facultad de ciencias, 2021. Español. ⟨NNT : 2021PAUU3023⟩. ⟨tel-03450908⟩

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