Physical and Theoretical Chemistry, Catalysis, Process Chemistry and Technology, Modeling and Simulation
12
Scopus Publications
Scopus Publications
The Role Metals of Second and 12th Group in the Oxidation of Ethylbenzene Nikolai V. Ulitin, Ildar N. Zalyaliev, Nikolai A. Novikov, Yana L. Lyulinskaya, Konstantin A. Tereshchenko, et al. International Journal of Chemical Kinetics, 2026 A kinetic model of ethylbenzene oxidation by air oxygen in the presence of 2‐ethylhexanoates of metals of the second and 12th groups (Mg, Ca, Sr, Ba, Zn, and Cd) as catalysts was constructed and parameterized using experimental data. Using the model, it is shown that: (1) in the range of 1–100 mmol/L, there exist initial concentrations of catalysts below which an increase in the initial catalyst concentration leads to an increase in the rate of ethylbenzene hydroperoxide formation in the oxidation of ethylbenzene (428 K, 1 atm, volume flow rate of air supply to the reactor of 0.018 m 3 /h, initial ethylbenzene concentration of 8.17 mol/L, initial concentrations of other species are 0), and above which it leads to a decrease (2‐ethylhexanoates of Mg, Ca, and Zn) or a plateau (2‐ethylhexanoates of Sr, Ba, and Cd); this is because the catalysts simultaneously accelerate the reactions of both formation and decomposition of ethylbenzene hydroperoxide, and starting from a certain initial catalyst concentration, the decomposition of ethylbenzene hydroperoxide begins to prevail over its formation; (2) the key reaction for the formation of ethylbenzene hydroperoxide and for ethylbenzene conversion in catalytic ethylbenzene oxidation, as in the non‐catalytic process, is the reaction between ethylbenzene and the peroxyl radical of ethylbenzene; the key reactions governing selectivity are the formation of methylphenylcarbinol and acetophenone from oxyl and peroxyl radicals of ethylbenzene; the role of the catalyst is to increase the concentrations of these radicals through the decomposition reactions of the intermediate adduct “ethylbenzene hydroperoxide + catalyst”; (3) Mg, Ca, Sr, Cd 2‐ethylhexanoates deactivate within 1 h of the ethylbenzene oxidation process, while Ba and Zn 2‐ethylhexanoates deactivate within 4 h (428 K, 1 atm, volume flow rate of air supply to the reactor of 0.018 m 3 /h, initial ethylbenzene, ethylbenzene hydroperoxide, and catalyst concentrations of 8.163, 0.022, and 5 mmol/L, respectively, initial concentrations of other species are 0); therefore, these catalysts should not affect the subsequent transformations of ethylbenzene hydroperoxide during propylene epoxidation in the Halcon process.
Catalytic Effect of Dibenzo-18-Crown-6 Ether Complexes With Group 2 Metal Chlorides on the Kinetics of Ethylbenzene Oxidation Ildar N. Zalyaliev, Nikolai V. Ulitin, Yana L. Lyulinskaya, Konstantin A. Tereshchenko, Natalia M. Nurullina, et al. International Journal of Chemical Kinetics, 2026 A kinetic model of ethylbenzene oxidation catalyzed by dibenzo‐18‐crown‐6 ether complexes with group 2 metal chlorides (Ca, Sr, Ba) was developed and parameterized using experimental data. Kinetic modeling demonstrated that: 1) an increase in the initial catalyst concentration from 1 to 100 mmol/L leads to a monotonic increase in the rate of ethylbenzene hydroperoxide formation (428 K, 1 atm, volume flow rate of air supply to the reactor of 0.018 m3/h, initial ethylbenzene concentration of 8.17 mol/L, initial concentrations of other species are 0), indicating that the formation of ethylbenzene hydroperoxide prevails over its decomposition; 2) catalysts deactivate within 1 h of the ethylbenzene oxidation process; thus, they are not affect subsequent transformations of ethylbenzene hydroperoxide during propylene epoxidation via the Halcon process; 3) among the dibenzo‐18‐crown‐6 ether complexes with group 2 metal chlorides, the complex with Ca chloride at an initial concentration of 5 mmol/L should be recognized as the best catalyst for industrial use (428 K, 1 atm, volume flow rate of air supply to the reactor of 0.018 m3/h, initial ethylbenzene concentration of 8.17 mol/L, initial concentrations of other species are 0), because it provides the same selectivity as that achieved in non‐catalytic ethylbenzene oxidation (about 80%) and reduces the time to reach 10% ethylbenzene conversion by a factor of three (from 1.5 h in the non‐catalytic process to 0.5 h in the catalytic process).
Effect of Monomer Mixture Composition on TiCl4-Al(i-C4H9)3 Catalytic System Activity in Butadiene–Isoprene Copolymerization: A Theoretical Study Konstantin A. Tereshchenko, Rustem T. Ismagilov, Nikolai V. Ulitin, Yana L. Lyulinskaya, Alexander S. Novikov Computation, 2025 Divinylisoprene rubber, a copolymer of butadiene and isoprene, is used as raw material for rubber technical products, combining isoprene rubber’s elasticity and butadiene rubber’s wear resistance. These properties depend quantitatively on the copolymer composition, which depends on the kinetics of its synthesis. This work aims to theoretically describe how the monomer mixture composition in the butadiene–isoprene copolymerization affects the activity of the TiCl4-Al(i-C4H9)3 catalytic system (expressed by active sites concentration) via kinetic modeling. This enables development of a reliable kinetic model for divinylisoprene rubber synthesis, predicting reaction rate, molecular weight, and composition, applicable to reactor design and process intensification. Active sites concentrations were calculated from experimental copolymerization rates and known chain propagation constants for various monomer compositions. Kinetic equations for active sites formation were based on mass-action law and Langmuir monomolecular adsorption theory. An analytical equation relating active sites concentration to monomer composition was derived, analyzed, and optimized with experimental data. The results show that monomer composition’s influence on active sites concentration is well described by a two-step kinetic model (physical adsorption followed by Ti–C bond formation), accounting for competitive adsorption: isoprene adsorbs more readily, while butadiene forms more stable active sites.
The Effect of Ca, Sr, and Ba Chloride Complexes with Dibenzo-18-Crown-6 Ether as Catalysts on the Process Criteria for the Efficiency of Cumene Oxidation (the First Stage in the Chain of Polymer Composite Production) Nikolai V. Ulitin, Nikolay A. Novikov, Yana L. Lyulinskaya, Daria A. Shiyan, Konstantin A. Tereshchenko, et al. Journal of Composites Science, 2023 A study was made on the effect of Ca, Sr, and Ba chloride complexes with dibenzo-18-crown-6 ether as catalysts on the process criteria of the efficiency of industrial cumene oxidation using kinetic modeling. It is the first stage in the process chain of polymer composite production. The kinetic scheme of the process is made of classical reactions of the radical chain mechanism (reactions of initiation, chain propagation, and chain termination), molecular reactions, reactions of formation of intermediate adducts “component of the reaction mixture—catalyst” and their decomposition, as well as reactions that take into account the specifics of the catalyst used: (1) formation of planar catalyst complexes with various substances; (2) formation of acetophenone along the catalytic path; (3) hydration of the intermediate adduct “α-methylstyrene—catalyst” to the required alcohol. It is shown that the kinetic model fully reproduces the experimental time dependencies of the cumene hydroperoxide concentration in the cumene oxidation and cumene hydroperoxide decomposition. Using the kinetic model, computational experiments were carried out, as a result of which the following conclusions were made: (1) among the considered catalysts, the complex of Sr chloride with dibenzo-18-crown-6 ether should be recognized as the best, provided that it is used at temperatures of 393–413 K and an initial concentration < 2 mmol/L; (2) to ensure selectivity comparable to the selectivity of a non-catalytic process, it is necessary to conduct the catalytic process at a lowest possible initial concentration of any of the considered catalysts.
