Research on Liquid-phase Aerobic Oxidation

The paper presents the results of studies on the reaction of liquid-phase aerobic oxidation of a mixture of C₁₀-C₂₀ hydrocarbons in the catalytic presence of nickel salts of natural petroleum acids (NPA) isolated from oil by leaching. The catalyst was preliminarily subjected to ultrasonic treatment for 1 minute in order to activate the particles. It is assumed that ultrasound contributes to the dispersion of particles and their uniform distribution in a mixture of hydrocarbons. It has been determined that the proposed scheme helps to accelerate the process of liquid-phase aerobic oxidation of hydrocarbons in a short time and increase the yield of target reaction products, namely synthetic fatty acids. It has been established that ultrasound used in autocatalysis of the oxidation of a mixture of hydrocarbons does not affect the process of accelerated conversion of hydrocarbons into oxygen-containing compounds and the acid number (A.n.), which is an indicator of the process of hydrocarbon oxidation, is equal to 7.5 mgKOH/g, with a reaction duration of 4 hours, and using a catalyst treated with ultrasound, this the number equates to 49.5 mgKOH/g for 5 hours. As a result of the research, it was noticed that the catalytic efficiency of micro-sized catalytic systems is increased through the use of irritating agents, that is, ultrasound. It is assumed that a synergistic effect is created between heterogeneous catalyst particles and ultrasound. Briefly, ultrasonication of catalyst particles causes them to disperse effectively, resulting in a wide active surface area of the catalyst.

Liquid-phase oxidation of paraffin hydrocarbons with molecular oxygen was carried out in a bubble-type oxidation unit in a glass reactor [1]. The nickel salt of natural petroleum acid (RCOO)₂Ni, used in the oxidation reaction of hydrocarbons as a catalyst, was synthesized in laboratory conditions, according to the method given in [2]. Ultrasonic treatment of the catalyst in a mixture of hydrocarbons C₁₀-C₂₀ was carried out on a cavitation installation of the Hielscher brand ((Ultrasound Technology, made in Germany) UP200St. In the cavitation process, titanium santrode of the s26d7 brand (Hielscher) was used, with a diameter of 7 mm and an amplitude of 190 µm.

The research results on liquid-phase aerobic oxidation of paraffin hydrocarbons with molecular oxygen in the presence of nickel salt of PNA treated with ultrasound are shown below in Table down (Т = 135-140⁰С, amount of air – 100-120l/h) (SFA - synthetic fatty acids; SOFA - synthetic oxyfatty acids):

As a result of the research, it was noticed that the catalytic efficiency of micro-sized catalytic systems is increased through the use of irritating agents, that is, ultrasound. It is assumed that a synergistic effect is created between heterogeneous catalyst particles and ultrasound. Briefly, ultrasonication of catalyst particles causes them to disperse effectively, resulting in a wide active surface area.

1. E Zeynalov, J Friedrich, A Aliyeva et.al. Plasma-chemically brominated single-walled carbon nanotubes as novel catalysts for oil hydrocarbons aerobic oxidation // Applied Catalysis A: General, Elsevier, 2013, 454, p. 115-118

2. A. Z. Aliyeva, H. C. Ibrahimov, E. G. Ismayilov, F. A. Amirov, N. M. Aliyeva. Effect of ultrasonic treatment of nanostructured Mn-containing catalyst for the oxidation of petroleum hydrocarbons // Theoretical and Experimental Chemistry, 2019, Vol. 55, No. 4, p. 287-292 (Russian Original 2019, Vol. 55, No. 4)