Síntese e estudo de estrutura/atividade de novos ésteres naftoquinônicos com atividade inibidora de deposição de parafina e depressora de fluidez em petróleos

• Autor(a) principal: Lemos, Bárbara Costa
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/10775
• topic: Paraffin deposition; Non-polymeric inhibitors; Pour point; Inibidores não poliméricos; Deposição de parafina; Ponto de fluídez; Química; Viscosidade; Petróleo; 54

The formation of paraffin crystals in petroleum tends to occur in any situation in which the oil suffers a decrease in temperature. This is one of the main and biggest problems of flux for transportation and production. In the cases which no intervention is performed, the crystals tend to agglomerate, increasing their sizes and leading to precipitation onthe walls of the pipe, decreasing its caliber. This hampers the oil flow and consequently causes various problems in the operation of transference. Aimingto minimize or overcome the setbacks numerous remediation techniques were developed such as the use of pigging, solvents, and chemical additives.The use of chemical additives, however, is becoming increasingly popular due to its easy application and lowercost. In this context, for the present work eight long-chainednon-polymericesters were synthesized mostly with good yields (84 to 97%). This new class of additives was rationalized with the purpose of determining the correlation structure/activity, described below, and to prospectthe maximum efficiency in the cited activities: the length and linearity of the alkylic chain, the sizeof the spacer that separates the polar nucleus and the ester group, the heteroatom bonded to the naphtoquinonic ring, and the effect of the ring polarity, with the exchange of the polar ringof naphtoquinonefor the nonpolar cyclohexyl. These esterswere tested in two Brazilian oils by pour pointassays and calorimetric experiments to determine the Wax Appearance Temperature (WAT) by Differential Scanning Calorimetry (DSC).Chromatographic assays were also performed to characterize the paraffinic portion of both oils, analyses by X-ray diffraction to determine WAT of additivated oil A and studies of thermal stability of the additives. For comparison the WAT and pour point depression tests were also performed to the crude and additivated oils with the commercial control NuFlo-151. From this comparison it was observed that the additives 1cand 1d, composed ofpalmitic and stearic acids, respectively, with the naphtoquinonic nucleus, and the spacer containing two carbon atoms and nitrogen as heteroatom, were the most effective inhibitors for the tested oils.The pour point values improved in up to 10 °C for oil A and18 °C for B. Furthermore, computational calculations proved thatthe presence of nitrogen heteroatom has as consequence a higher polarization of the naphtoquinonic nucleus, which in turn was shown to be essential to the higher efficiency of the inhibitor. This new class of additives based on quinones presented better results than the commercial tested, even when applied in concentrations lower than those related in the literature. Stands out the benefit of the non-polymeric structure of the unpublished additives synthesized, since it is known that polymers do not have mechanical resistance. This fact mitigates, at least partially, the need of continuous replacement of additive