Emiliya Ivanchina

Thermodynamic stability of coke-generating compounds formed on the surface of platinum dehydrogenation catalysts in their oxidation with water

Results of thermodynamic analysis and mathematical simulation of the deactivation of a platinum dehydrogenation catalyst by coke-generating compounds are presented. An approach to increasing the catalyst on-stream time has been proposed, suggesting implementation of a procedure for calculating the optimal flow rate of water fed to the reactor to maintain the conditions of thermodynamic equilibrium of the coke formation reaction and oxidation of intermediate condensation products with water.

Effect of thermodynamic stability of higher aromatic hydrocarbons on the activity of the HF catalyst for benzene alkylation with C9-C14 olefins

Results of thermodynamic analysis of reactions occurring during the alkylation of benzene with C9-C14 olefins, including the reversible reactions of formation of high-molecular-mass aromatic hydrocarbons, are presented. The thermodynamic relationships revealed have formed the basis for deriving a mathematical model of the alkylation process with allowance for alteration in the activity of the HF catalyst. It has been shown that the buildup of higher aromatic hydrocarbons in the alkylation reactor has a detrimental effect on the properties of HF. Operating modes and controlling parameters of the main stages of the production f linear alkylbenzenes to ensure the maximal efficiency of the process and maintain the activity of the HF catalyst at the optimal level have been determined.

Computer Program for Optimizing Compounding of High-Octane Gasoline

A procedure for calculating octane numbers of commercial gasolines with due regard for the intensity of interaction between molecules of blend components, and the mechanism of interaction of interaction of anti-knock additives with hydrocarbons is elaborated. Based on the models developed, a computer program is created for optimization of the process producing high-octane gasoline. The program allows quick and precise determination of the optimum ratio of components, which ensures production of commercial gasolines that meet all the requirements of regulatory documents.

Determination of the Optimal Operation Mode of the Platinum Dehydrogenation Catalysts

The main results of thermodynamic analysis and mathematical simulation of the deactivation of a platinum dehydrogenation catalyst by coke-generating compounds are presented. Developed model allows calculating the optimal flow rate of water fed to the reactor to maintain the conditions of thermodynamic equilibrium of the coke formation reaction and oxidation of intermediate condensation products with water. A comparative evaluation of different raw cycles of platinum-dehydrogenation catalysts is presented and shown to cause reduced production of the desired product was the change the composition of the feedstock.

Intensification of the processes of dehydrogenation and dewaxing of middle distillate fractions by redistribution of hydrogen between the units

The dehydrogenation and dewaxing of hydrocarbons of middle-distillate fractions, which proceed in the hydrogen medium, are of great importance in the petrochemical and oil refining industries. They increase oil refining depth and allow producing gasoline, kerosene, and diesel fractions used in the production of hydrocarbon fuels, polymer materials, synthetic detergents, rubbers, etc. Herewith, in the process of dehydrogenation of hydrocarbons of middle distillate fractions (C9–C14) hydrogen is formed in the reactions between hydrocarbons, and the excess of hydrogen slows the target reaction of olefin formation and causes the shift of thermodynamic equilibrium to the initial substances. Meanwhile, in the process of hydrodewaxing of hydrocarbons of middle distillate fractions (C5–C27), conversely, hydrogen is a required reagent in the target reaction of hydrocracking of long-chain paraffins, which ensures required feedstock conversion for production of low-freezing diesel fuels. Therefore, in this study we suggest the approach of intensification of the processes of dehydrogenation and dewaxing of middle distillate fractions by means of redistribution of hydrogen between the two units on the base of the influence of hydrogen on the hydrocarbon transformations using mathematical models. In this study we found that with increasing the temperature from 470 °C to 490 °C and decreasing the hydrogen/feedstock molar ratio in the range of 8.5/1.0 to 6.0/1.0 in the dehydrogenation reactor, the production of olefins increased by 1.45–1.55%wt, which makes it possible to reduce hydrogen consumption by 25,000 Nm3/h. Involvement of this additionally available hydrogen in the amount from 10,000 to 50,000 Nm3/h in the dewaxing reactor allows increasing the depth of hydrocracking of long-chain paraffins of middle distillate fractions, and, consequently improving low-temperature properties of produced diesel fraction. In such a way cloud temperature and freezing temperature of produced diesel fraction decrease by 1–4 °C and 10–25 °C (at the temperature of 300 °C and 340 °C respectively). However, when the molar ratio hydrogen/hydrocarbons decreases from 8.5/1.0 to 6.0/1.0 the yield of side products in the dehydrogenation reactor increases: the yield of diolefins increases by 0.1–0.15%wt, the yield of coke increases by 0.07–0.18%wt depending on the feedstock composition, which is due to decrease in the content of hydrogen, which hydrogenates intermediate products of condensation (the coke of amorphous structure). This effect can be compensated by additional water supply in the dehydrogenation reactor, which oxidizes the intermediate products of condensation, preventing catalyst deactivation by coke. The calculations with the use of the model showed that at the supply of water by increasing portions simultaneously with temperature rise, the content of coke on the catalyst by the end of the production cycle comprises 1.25–1.56%wt depending on the feedstock composition, which is by 0.3–0.6%wt lower that in the regime without water supply.

Comparative analysis of catalyst operation in the process of higher paraffins dehydrogenation at different technological modes using mathematical model

Abstract This paper presents the results of comparative analysis of three run cycles of platinum catalyst for higher paraffins C9–C14 dehydrogenation process, performed using mathematical model. The results of model calculations were compared with the experimental data obtained at the industrial unit. It was established that deactivation of the platinum dehydrogenation catalyst is influenced by the technological modes of its operation, such as temperature, pressure, hydrogen/feedstock molar ratio and water supply. In the process of higher paraffins dehydrogenation, the phenomenon of platinum catalyst self-regeneration is observed. This occurs due to the action of feedstock components, in particular water and hydrogen involved in oxidation and hydrogenation of intermediate condensation products (coke structures). Model calculations showed that with a decrease in the hydrogen/feedstock molar ratio and simultaneous increase in water supply, depending on the temperature and composition of feedstock, it is possible to slow down deactivation process and increase the catalyst service life. This fact was experimentally confirmed at industrial unit.

Influence of Feedstock Group Composition on the Octane Number and Composition of the Gasoline Fraction of Catalytically Cracked Vacuum Distillate

Thermodynamic parameters for the reactions of vacuum distillate catalytic cracking in a riser reactor have been calculated using the density functional theory. The list of the reactions has been compiled on the basis of laboratory studies on determining the group and structural-group composition of the vacuum distillate and the results of thermodynamic analysis. A kinetic model of the catalytic cracking process has been developed on the basis of a formalized scheme of the hydrocarbon conversion mechanism. By using the kinetic model derived, the effect of the group composition of four vacuum distillate samples on the octane number and the composition of the gasoline fraction of the catalytic cracking process has been assessed.

Prediction of the light product yield from the catalytic cracking unit using the mathematical model

The research performed in this work are aimed at the optimization of technological mode to increase the yield of light fractions (gasoline and diesel) in the catalytic cracking of vacuum distillate taking into account feedstock composition. The calculations were performed using the mathematical model of a catalytic cracking, developed on the basis of a formalized scheme of hydrocarbons transformations in the catalytic cracking. To increase the yield of gasoline and diesel fraction the optimal technological modes were determined, taking into account the composition of the feedstock.

Testing of cracking zeolite catalysts using mathematical model

The testing results of the cracking zeolite catalysts using the mathematical model of catalytic cracking are given in this research. The mathematical model is based on the formalized scheme of hydrocarbon conversions according to the results of laboratory research using gas chromatography-mass spectrometry and thermodynamic analysis of the catalytic cracking reactions using quantum chemistry methods. The effect of the catalyst composition on the distribution of the catalytic cracking products, the content of propane-propylene and butane-butylene fraction in wet gas, group composition and octane number of gasoline, the content of coke on the catalyst are determined using the mathematical model of catalytic cracking.

Mathematical modeling of diesel fuel hydrotreating

Hydrotreating of the diesel fraction with the high initial sulfur content of 1,4 mass% is carried out in the flow-through laboratory setup with the industrial GKD-202 catalyst at various process temperature. On the basis of the experimental data the regularities of the hydrogenation reactions are revealed, and the formalized scheme of sulfur-containing components (sulfides, benzothiophenes, and dibenzothiophenes) transformations is made. The mathematical model of hydrotreating process is developed, the constant values for the reaction rate of hydrodesulfurization of the specified components are calculated.