Characterization of commercial ceramic adsorbents and its application on naphthenic acids removal of petroleum distillates

Abstract

The mixture of carboxylic acids present in petroleum oil and directly responsible for its acidity and corrosiveness in liquid phase during the refine process is denominated "naphthenic acids". These acids are also present in distilled fraction of petroleum, causing several problems in final products quality. A possible way to remove the carboxilic acids from petroleum distilled fractions is the adsorption in porous materials. However, the results obtained until now indicate that ion exchange resins would be the best adsorbents for this process, which would probably increase its cost. In this work, two commercial adsorbents (clay and activated alumina) were characterized by a set of physical-chemistry techniques and evaluated concerning their capacity of removing naphthenic acids from a light petroleum fraction. It was verified the influence of a thermal treatment previous to the adsorption in its physical-chemistry characteristics and its properties. A high reduction of the TAN values was verified in the residual oils from both adsorbent, although there was a competition among all the compounds present in the light oil fraction for the adsorption sites, which can be probably related to the thermal pre-treatment. These results were related to corrosion yield experiments, and it was observed that the adsorbent pretreatment also affected the reduction in corrosion yields for both alumina and clay

Study of Naphthenic Acidity and Corrosivity of Brazilian Crude Oils by ESI(-) FT-ICR MS

“…Para cada espectro, processamentos automatizados foram realizados para designar fórmulas moleculares aos picos com sinal/ruído maior que três (> 3). Os elementos permitidos foram o 12 C, 13 7 (a) Cupom de aço inoxidável 316L; (b) Aquecimento a 180 °C da amostra de óleo com o cupom imerso, por vinte horas; (c) Retirada do cupom; (d) lavagem do cupom, inicialmente com querosene por quatro min, seguido por limpeza com solução de Clark para retirada do produto de corrosão A taxa de corrosão foi calculada pela Equação 4 (Eq. 4), onde mi e mf são as massas iniciais e finais do cupom de aço, respectivamente, t é o tempo de experi e to, ρ é a de sidade da liga etálica (7,86 g cm -3 ) e A é a área exposta do cupom.…”

“…6 Esse número é denominado erroneamente por alguns autores como "acidez naftênica", no entanto outros tipos de compostos ácidos além dos ácidos naftênicos contribuem em seu valor, tais como compostos sulfurados, nitrogenados e aromáticos. 6,7 A determinação do TAN tem sido rotineiramente empregada para avaliar a corrosividade do petróleo, considerando-se óleos com número de acidez total maior que 0,5 mg de KOH/g de óleo como sendo potencialmente corrosivos. No entanto, sabese atualmente que este não é um indicador totalmente confiável, já que diferenças significativas na corrosividade de óleos com o mesmo TAN têm sido observadas.…”

Clay Adsorption Perspective on Petroleum Refining Industry

“…Acid activation can be affect the physicochemical properties of bentonites and galuconite [37,48]. It was concluded that acid bentonite clays are usually used as oil bleaches, which can favor the adsorption of aromatic color compounds and decrease the adsorption of others compound, mainly naphthenic acids and sulfur compounds [48].…”

“…Additionally, the higher concentrations of NA in crude oils reduce the quality and market at a lower price [53]. Silva et al [48] studied the reducing of corrosion by removing NA from a light petroleum fraction using two commercial adsorbents (clay and activated alumina). Both adsorbents proved a high reduction of the total acid number (TAN) in the residual oils.…”

“…It was observed that the adsorption of acid composites of the oil significantly influenced by the thermal pre-treatment of clay. Additionally, the pre-treatment by adsorption affected the reduction in corrosion yields and the corrosion rate of the mild steel cupons decreased in the residual oils originated from the adsorption processes for both adsorbents [48]. Xiaohui et al, [13] studied the adsorption of NA from dewaxed vacuum gas oil during lube base oil refining using a commercial grade activated clay.…”