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UNIVERSUM:
ТЕХНИЧЕСКИЕ НАУКИ
ноябрь, 2023 г.
DOI -10.32743/UniTech.2023.116.11.16286
STUDYING THE ACTIVITY OF THE CATALYST DURING THE PRODUCTION PROCESS
OF SYNTHETIC LIQUID HYDROCARBONS
Oybek Kuyboqarov
Candidate of Technical Sciences, Karshi Engineering and Economic Institute, Republic of Uzbekistan, Karshi E-mail: [email protected]
Fazilat Egamnazarova
Senior Lecturer, Karshi Engineering and Economic Institute, Republic of Uzbekistan, Karshi E-mail: _ [email protected]
Bobojon Jumaboyev
Senior Lecturer, Karshi Engineering and Economic Institute, Republic of Uzbekistan, Karshi
ИЗУЧЕНИЕ АКТИВНОСТИ КАТАЛИЗАТОРА В ПРОЦЕССЕ ПРОИЗВОДСТВА СИНТЕТИЧЕСКИХ ЖИДКИХ УГЛЕВОДОРОДОВ
Куйбогаров Ойбек Эргашович
канд. техн. наук,
Каршинский инженерно-экономический институт, Республика Узбекистан, г. Карши
Эгамназарова Фазилат Дустцобиловна
ст. преподаватель, Каршинский инженерно-экономический институт, Республика Узбекистан, г. Карши
Жумабоев Бобожон Олимжонович
ст. преподаватель, Каршинский инженерно-экономический институт, Республика Узбекистан, г. Карши
ABSTRACT
It was studied depending on the performance of promotion of 15% Co-15% Fe/HZS with group VIII and IV metals (Ni, Zr) in the synthesis of CO and H2 hydrocarbons. The addition of Ni and Zr metals to the So and Fe storage catalyst resulted in an increase in the yield of liquid hydrocarbons from 118 to 124-139 g/m3. As a result of research, a 15%Co-15%Fe-5%Ni-1%ZrO2/HZS dispersed catalyst was selected. The catalytic activity of the selected catalyst is controlled by the time and method of initial treatment and the study of the catalytic action of diluting the catalytic system with quartz. it was found that the selectivity of production increases from 72 to 85%. A noticeable decrease in the total productivity of gaseous participants was observed (from 96 to 52 g/m3). Increasing the dilution of the catalyst with quartz also led to a decrease in the proportion of ethylene hydrocarbons and an increase in the content of saturated hydrocarbons from the liquid surfaces of the synthesis.
АННОТАЦИЯ
Изучена зависимость эффективности промотирования 15% Со-15% Fe/ЮКЦ металлами VIII и IV групп (Ni, Zr) в синтезе СO и H2 углеводородов. Добавление в катализатор хранения Co и Fe металлов Ni и Zr привело к увеличению выхода жидких углеводородов со 118 до 124-139 г/м3. В результате исследований был выбран дисперсный катализатор 15%Co-15%Fe-5%Ni-1%ZrO2/ЮКЦ. Каталитическая активность выбранного катализатора контролируется временем и способом первичной обработки, а также исследованием каталитического действия разбавления каталитической системы кварцем установлено, что селективность производства увеличивается с 72 до 85%.
Библиографическое описание: Kuyboqarov O.E., Egamnazarova F.D., Jumaboyev B.O. STUDYING THE ACTIVITY OF THE CATALYST DURING THE PRODUCTION PROCESS OF SYNTHETIC LIQUID HYDROCARBONS // Universum: технические науки: электрон. научн. журн. 2023. 11(116). URL: https://7universum.com/ru/tech/archive/item/16286
A UNiVERSUM:
№11(116)_ДД ТЕХНИЧЕСКИЕ НАУКИ_ноябрь. 2023 г.
Наблюдалось заметное снижение общей продуктивности газообразных участников (с 96 до 52 г/м3). Увеличение разбавления катализатора кварцем также привело к уменьшению доли этиленовых углеводородов и увеличению содержания предельных углеводородов с жидких поверхностей синтеза.
Keywords: catalyst, regeneration, carbon monoxide, hydrogen, liquid hydrocarbons, conversion, reaction yield, dilution. Ключевые слова: катализатор, регенерация, оксид углерода, водород, жидкие углеводороды, конверсия, выход реакции, разбавление.
1. Introduction
GTL (Gas-to-Liquid) technologies are technologies for processing natural gas into motor fuel and other heavier hydrocarbon products. The synthesis of hydrocarbons from CO and H2 is an exothermic reaction. The thermal effect reaches 600 kcal/Nm3 of synthesis gas or 41 kcal/mol. The activation energy of the process is about 24 kcal/mol. From carbon monoxide and hydrogen, the formation of hydrocarbons of any molecular weight, type and structure, except acetylene, is thermo-dynamically possible [1].Mixtures with a wide fractional composition (from C1 to C30 and even up to C100 and higher), including paraffin and olefinic hydrocarbons, have been synthesized. Thermodynamic calculations show that at a pressure of 1-100 atm and a temperature of 20-700 ° C, paraffinic hydrocarbons, especially methane, are most likely to be formed. The upper temperature limit for the formation of hydrocarbons at a pressure of 1atm is 400-500 ° C. With an increase in pressure to 100 atm, this temperature increases to about 150-200 ° C. A decrease in temperature contributes to an increase in the equilibrium level of carbon monoxide conversion. The lower the temperature, the more favorable the thermodynamic properties for the synthesis of all homologous series compounds from CO and H2.In practice, the lower temperature limit is determined by the temperature at which the catalyst is active. In addition, secondary processes are possible in the entire temperature range used for the synthesis of hydrocarbons from CO and H2: hydrogenation of alkenes, hydrocracking
of the resulting alkanes, dehydrogenation of alkanols, isomerization processes, oligomerization, double bond migration, polymerization, cis -trans isomerization.me-thane - alkanes - alkenes - products containing oxygen. The probability of formation of normal alkanes decreases with increasing chain length; for simple alkenes, the order is reversed [2]. An increase in synthesis temperature favors the formation of alkenes and aldehydes. An increase in the total pressure in the system favors the formation of high molecular weight products, and an increase in the partial pressure of hydrogen in the synthesis gas leads to the predominant formation of alkanes [3]. Thus, hydrogen-rich syngas is preferred for alkanes production, while carbon monoxide-enriched syngas helps to increase the yield of alkenes and aldehydes, if coke formation is not considered. For paraffins with the same number of carbon atoms in the molecule, the n-al-kane/iso-alkane equilibrium ratio increases with product chain length and is, for example, 1.1 for butanes and 19.2 for nonanes [4]. However, the composition of the products of the catalytic synthesis of hydrocarbons from CO and H2 is significantly different from the equilibrium. Fischer-Tropsch synthesis is a kinetically controlled process, and the nature of the catalyst and the synthesis conditions affect the distribution of products [5]. The synthesis of hydrocarbons from CO and H2 can legitimately be considered a polycondensation process, since the molecular weight distribution of the synthesis products, as a rule, obeys the formal kinetics of polymerization:
where M is a metal, C1, Cn-1, Cn, Cn+1 is a carbon fragment containing 1, 1-n, n, n+1 carbon atoms, respectively, k1 and k2 are chain growth rate constants and corresponding to finish
The simplest, but at the same time adequate model is based on the following assumptions [6]:
• after each introduction of C1 monomer molecule, the next step of chain elongation with rate constant k1 or chain termination with rate constant k2 can occur, which leads to the formation of the next observed product;
• chain growth and termination rate constants k1 and k2 are independent of chain length.
A large amount of products of secondary changes (cracking, isomerization) - isoparaffins and olefins -was found in all fractions of synthesized hydrocarbons. The most amount of isoparaffinswas recorded for the composite catalyst - the iso/n parameter is equal to 0.6, which indicates that it has increased activity compared to the catalysts absorbed in the hydroimprovement reactions. High concentrations of olefins were found for catalysts with low cobalt content, which is due to their low hydrogenation capacity compared to unsaturated hydrocarbons [7].
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Figure 1. Molecular-mass distribution of C5+ hydrocarbons obtained in the presence of catalysts: a-Co-Fe-Ni-ZrO2/HZS+ Fe3O4+d-FeOOH; 0-absorbent, containing 6.5% iron
The use of zeolite in the composition of hybrid catalysts allows obtaining C5+ hydrocarbons whose molecular-mass distribution does not obey the AShF equation. Maximum MMD corresponds to C5-C10 hydrocarbons. The products consist mainly of liquid hydrocarbons. The selectivity in the formation of C5-C18 hydrocarbons for absorbing catalysts is 46-49%, for the composition it is 62.6% (Fig. 1).Thus, it was found that the use of cobalt mixing and cobalt precipitation methods by impregnation into the formed carrier has a significant effect on the physicochemical and catalytic properties of hybrid catalysts.
The use of the absorption method for the preparation of hybrid catalysts creates a system that exhibits lower catalytic properties in the process of hydrocarbon synthesis than the composite catalyst. This is likely due to both diffusion factors, pore blocking by precipitated cobalt, and the formation of compounds of cobalt and aluminum oxides that are difficult to recover from oxideoxide interactions.
2. Methods of research
Hydrocarbon synthesis centers and zeolitic acid sites in absorbent catalysts are in close contact with each other, which should contribute to the enhancement of secondary processes. At the same time, the amount of liquid hydrocarbons (C5-C18) in the composition of C5+ hydrocarbons is about 83%, which is 12% less than that of the composite catalyst.For the composite catalyst prepared by mixing the components, no oxide-oxide interaction was found, the pores of the zeolite are not blocked by cobalt, which allows efficient delivery of reactants to the active part of hydrocarbon synthesis.
Such a catalyst has a high activity in the synthesis of hydrocarbons - the conversion rate of CO is 76.2%, the productivity and selectivity for C5+ hydrocarbons is 93.8 kg/m3 cat h and 68.6%.
In the composite catalyst salted in silicon oxide, the acid center is not blocked by the cobalt located on the silicon oxide in the Co-Fe-Ni-ZrO2/HZS+Fe3O4+d-FeOH catalyst. There are both external and internal centers for hydrocarbons, as a result of which the composite catalyst increases the activity in hydrolysis reactions -the amount of liquid hydrocarbons reaches 95%. In this context, the preferred method for the preparation of hybrid catalysts is to mix the active components using a binder [8].
3. Results
The effect of CO pressure during the activation stage on the main parameters of the synthesis. In order to obtain more information about the effect of CO pressure on the activity of 15%Co-15%Fe-5%Ni-1%ZrO2/HZS FeOH nano-sized catalyst during the activation stage, we conducted detailed studies. .The main parameters of the synthesis of catalysts obtained by activation at different pressures of CO are presented in Table 1. It can be seen that the pressure of CO, as in the case of hydrogen, does not significantly affect the main parameters of the synthesis of hydrocarbons from CO and H2 in the nanohet-erogeneous catalyst. In all studied ranges of pressures, CO conversion was ~78%, yield of liquid products of synthesis was ~120 g/m3, selectivity for C5+ was 62%, productivity was 478.8 g/kgcath [9].
Table 1.
Effect of regeneration conditions of 15%Co-15%Fe-5%Ni-1%ZrO2/HZS
№ P, атм Kco % Fruit,, C5+ g / m3 S, C5+ , % Selektivity, g/kg^cat^hour.
1 1 82 132 47 517
2 2 68 109 63 441
3 5 76 118 65 454
4 7 80 107 75 465
5 10 74 124 60 484
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Figure 2.2 shows the dependence of the output of the target products of synthesis - liquid hydrocarbons on CO conversion. As can be seen from the table, it can be concluded that the obtained dependences are almost
independent of the CO pressure during the regeneration stage. All of them are almost linear, which indicates good heat dissipation [10].
20 4(» 60
Figure 2. Effect of CO pressure on the activation stage
The gas pressure during the regeneration stage has it is observed that by-products oxygenates, especially
almost no effect on the fractional and group composition ethanol, are formed more [11-12].
of the target products of the synthesis - liquid hydrocarbons (Table 2). However, when the pressure increases,
Table 2.
Effect of CO pressure on the liquid hydrocarbon composition during the 15%Co-15%Fe-5%Ni-1%ZrO2/HZS FeOH catalyst activation
№ Pressure, atm Liquid hydrocarbons Oxygenates, %
C - C C5 C10 C — C C11 C18 C Olefins [Oxy] (CH3)2 O Cl C2 C3+
1 1 79 12 9 47 20 1 2 14 3
2 2 82 15 3 52 20 1 2 13 3
3 5 80 17 3 51 23 1 3 16 3
4 7 83 13 4 46 32 1 3 23 5
5 10 82 13 5 48 26 1 2 20 3
4. Conclusions
Thus, nano-sized samples of the nanocatalyst with 15%Co-15%Fe-5%Ni-1%ZrO2/HZS FeOH composition were prepared by the method of thermolysis of appropriate salts of precursors or their solutions in a dispersion medium boiling at high temperature in a wide temperature range,
and in the presence of this catalyst, the effect of catalyst concentration in the reaction zone, the effect of zirconium concentration in the reaction space, the effect of regenerator properties, the effect of regeneration conditions, the effect of CO pressure in the activation stage, and the effect of synthesis conditions studied.
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