Estudo da evolução de ácidos orgânicos no processo de destilação de petróleos

• Autor(a) principal: Machado, Flora Gomes
• Data de Publicação: 2014
• 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/10/4704
• topic: naphthenic acidity; thermal degradation; distillation; short-chain acids; ion chromatography; Acidez naftênica; degradação térmica; ácidos de cadeia curta; Petróleo; Análise cromatográfica; Destilação; Química; 54

The presence of naphtenic acids in petroleum and its effects are well described in the literature, especially the term "naphthenic corrosion". Traditionally, the structure of naphthenic acids include the presence of at least one ring having five or six saturated carbon atoms. Currently this term also includes linear acids. The content of naphthenic acids is usually represented by the total acid number (TAN), which is reported in mg KOH.g-1 sample. Studies suggest that the corrosion rate is not directly related to the values of TAN, but are dependent on the structure of the acidic species present in the oil, the operating temperature, sulfur content, among others. These acids are presents at the oils in relatively low concentrations. Depending on the boiling point of these compounds, they may concentrate on certain sections during the distillation process and cause non-aqueous corrosion at elevated temperatures. The short-chain acids, especially one to four carbon atoms, concentrates on top of the refinery towers exacerbating corrosion of the aqueous solutions present in these systems. Thus, the objective of this study is to perform the measurement and speciation of acids from one to four carbon atoms which during the distillation process of crude Brazilian reaches the top of the distillation column, and study the possible thermal degradation during the distillation process of the acidic species of higher molecular mass. The methodology of this work covers the distillation of oils from different sources in laboratory manual distillation unit adapted to capture acids at the top of the column. We carried out a quantitative study of the acidity of crude oils, cuts and waste generated after submission to ASTM D2892. Through the acids capture system was generated an aqueous extract which were quantitatively analyzed formic, acetic, propionic and butyric acids by ion chromatography. By mass balance of acidity, in general, the initial acidity of the oil was greater than the acidity of cuts and residue after distillation, suggesting a loss of acidity by thermal degradation of naphthenic acids. The analyses of extracts obtained from the top of column showed significant levels of short chain organic acids.