Antioxidant properties of nitrogenous bases separated from petroleum

The article presents the results of a study of the composition, structure and the possibility of using nitrogenous bases isolated from the vacuum distillate of low-paraffinous oil from the Neft Dashlary oil field as an antioxidant additive. The physicochemical characteristics and structural features of concentrates K1 (dissolved in pentane) and K2 (dissolved in benzene) were determined. The proportion of K1, nitrogenous bases soluble in pentane was 85 % wt/; in benzene, K2 – 15 % wt. Based on the results of concentrate analysis using IR and PMR spectroscopy, the average molecules K1 contain 2.22; K2 – 2.42; aromatic rings, one of which in both is heteroaromatic K*a.het. = 0.97–0.72. In order to determine the inhibitory properties, the concentrates were tested as an additive to petroleum oil – T-46, both independently and in combination with other additives. A comparatively greater effect as an antioxidant was achieved in combination with other additives: 1) anti-corrosion – B 15/41 (acidic ester of alkenyl succinic acid), demulsifying – D-157 (block copolymer of ethylene and propylene oxides); anti-foam PMS-200A (polymethylsiloxane liquid); concentrate of nitrogenous bases instead of expensive ionol – 2,6-di-tret-butylphenol. Tests have shown that with a content of up to 0.05 % in the composition of the concentrate of nitrogenous bases instead of 0.5 % by weight of ionol, during oil oxidation under the conditions of the standard requirements, oils are obtained that differ from the existing ones in improved antioxidant properties, they are also cheaper. When the ratio of nitrogen base concentrate to the sum of additives is less than 0.3, and also when it increases to 0.55, a precipitate is formed, the stability after oxidation according to ASTM D-943 becomes insufficient. Thus, the isolated nitrogen base concentrates contain aromatic structures with heteroatoms and functional groups with a mobile hydrogen atom, as well as alkyl substituents, which significantly affect the antioxidant activity.