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л Д UNIVERSUM:
№ 12 (129)_¿Л ТЕХНИЧЕСКИЕ НАУКИ_декабрь. 2024 г.
DOI - 10.32743/UniTech.2024.129.12.18799
CATALYTIC SYNTHESIS OF ETHYLENE SERIES HYDROCARBONS
FROM DIMETHYLPHYR
Nazarbek Egamberdiev
Assistant
of the Uzbek-Finnish Pedagogical Institute, Uzbekistan, Samarkand E-mail: [email protected]
Normurot Fayzullaev
Doctor of Chemical Sciences, Professor Samarkand State University named after Sh. Rashidov,
Uzbekistan, Samarkand E-mail: _ [email protected]
Eldor Ismoilov
Doktorant
of the Samarkand State University named after Sh. Rashidov,
Uzbekistan, Samarkand
КАТАЛИТИЧЕСКИЙ СИНТЕЗ УГЛЕВОДОРОДОВ ЭТИЛЕНОВОГО РЯДА
ИЗ ДИМЕТИЛФИРА
Эгамбердиев Назарбек Шавкатович
ассистент
Узбекско-Финнского педагогического института, Республика Узбекистан, г. Самарканд
Файзуллаев Нормурот Ибодуллаевич
д-р хим. наук, профессор,
Самаркандский государственный университет имени Ш. Рашидова,
Республика Узбекистан, г. Самарканд
Исмаилов Эльдор Халилович
докторант
Самаркандского государственного университета имени Ш. Рашидова,
Республика Узбекистан, г. Самарканд
ABSTRACT
The work studied the kinetics of the process of obtaining unsaturated ethylenic hydrocarbons - ethylene, propylene and butylenes - from dimethyl ether, as well as the characteristics of the catalyst. The catalysts were obtained by mixing the suspension and further shaping the resulting products. To increase the catalytic activity of the catalyst, it was modified with zinc, copper and zirconium compounds.
In this work, highly efficient catalysts with a completely new composition were developed for the catalytic conversion of dimethyl ether to unsaturated ethylenic hydrocarbons (ethylene, propylene, and butylenes), and the effect of the nature of the modifying element, as well as high-temperature treatment of the catalyst with water vapor, on the textural, acidic characteristics, and catalytic properties of the catalyst was studied.
АННОТАЦИЯ
В работе изучены кинетические закономерности процесса получения ненасыщенных этиленовых углеводородов - этилена, пропилена и бутилена из диметилового эфира, а также характеристики катализатора. Катализаторы получали путем перемешивания суспензии и дальнейшего формирования полученных продуктов. Для повышения каталитической активности катализатора его модифицировали соединениями цинка, меди и циркония.
Библиографическое описание: Egamberdieyv N.Sh., Fayzullaev N., Ismoilov E.X. CATALYTIC SYNTHESIS OF ETHYLENE SERIES HYDROCARBONS FROM DIMETHYLPHYR // Universum: технические науки : электрон. научн. журн. 2024. 12(129). URL: https://7universum.com/ru/tech/archive/item/18799
A UNIVERSUM:
№ 12 (129)_¿Л ТЕХНИЧЕСКИЕ НАУКИ_декабрь. 2024 г.
В данной работе при каталитической конверсии диметилового эфира в непредельные углеводороды этиленового ряда (этилен, пропилен и бутилен) разработаны высокоэффективные катализаторы с совершенно новым составом и природой модифицирующего элемента, а также высокотемпературной обработки. катализатора водяным паром, изучены текстура и кислотные характеристики катализатора, а также их влияние на каталитические свойства.
Keywords: methanol, ethylene, propylene, conversion, catalyst, zeolite. Ключевые слова: метанол, этилен, пропилен, конверсия, катализатор, цеолит.
Inroduction
The production of lower molecular weight ethylene series hydrocarbons is extensive and constantly growing [1]. The most popular and studied method of obtaining chemical products from natural gas is the production by pre-conversion of natural gas into synthesis gas (CO/N2).
Currently, there is great interest in the option of obtaining C2-C3 ethylene hydrocarbons from synthesis gas via dimethyl ether, which allows the production of low-molecular ethylene hydrocarbons with high productivity and high selectivity [2, 3].
Dimethyl ether can be considered as one of the main possible means for converting non-oil raw materials into valuable chemical products such as ethylene series hydrocarbons [4]. A new catalyst for the synthesis of low molecular weight ethylene series hydrocarbons from dimethyl ether is a high-silica zeolite of the ZSM-5 type. The targeted effect on the properties of zeolite catalysts is modification with metal compounds [5-9], which can lead to a change in their textural and acidic properties [10-12]. In the literature, there are many works that have extensively studied the effect of the nature of the modifying element on the properties of zeolite catalysts [13-17].
The change in the acidic properties can also be achieved by pre-treating the catalysts at high temperatures or by changing the water content in the feedstock. In this regard, it is very relevant to obtain information on the effect of acidic properties on the catalytic properties of zeolite catalysts for the conversion of dimethyl ether to hydrocarbons such as ethylene.
In this case, it is important to conduct studies that allow us to assess the influence of the nature of the modifying element not only on the activity, but also on the stability of the catalytic properties. This is especially important when carrying out the reaction in a water vapor environment, which is used in a number of industrial process technologies [18-21].
Experience part:
The ASAP 2020 analyzer program allows you to calculate the textural properties of mesoporous high-silica zeolite sorbents with high adsorption properties using various methods.
The specific surface area of the pores was calculated using the Brown-Emmett-Taylor (BET), Langmuir and density functional theory (DFT) methods. The specific surface area of the micropores was estimated using the comparative t-plot and MR methods, as well as the
Dubinin-Radushkevich and Dubinin-Astakhov methods. The micropore volume was determined using the comparative t-plot and MR method, DFT, as well as the Dubinin-Astakhov and Horvat-Kawazoe methods. The mesopore volume was determined using the Barrett-Joyner-Halenda (BJH) and Horvat-Kawazoe methods. The average pore diameter was estimated using the BET, BJH, Dollimore-Heal and MR methods using the formula Average=4Vads/S.
During desorption, the gas phase substance passes through the katharometer cell, the resulting signal is recorded and processed on a computer using software. High-resolution transmission electron microscopy (TEM) images were obtained on JEM-2010 and JEM-2200FS electron microscopes with a structure resolution of 0.14 and 0.1 nm, respectively. Energy dispersive X-ray (EDX) spectra and elemental maps were obtained on a JED-2300T spectrometer in dark field mode in scanning mode on the JEM-2200FS device. RFES spectra were recorded on an ES300 photoelectron spectrometer in the constant transmission energy mode of the photoelectron energy analyzer.
Zr-YKS crystals with a size of 1-3 ^m are mixed with cloud-like particle aggregates with a size of 50-100 nm. The spongy particles have mesopores with a diameter of 10-20 nm.
Discussion of results:
Further increase in the selectivity of ethylene and propylene, the first representatives of unsaturated ethylene series hydrocarbons, is achieved mainly through technological solutions. The aim of this research is to create a highly efficient modified catalyst with properties such as high catalytic activity, selectivity and productivity, and to develop technological methods for regulating the yields and ratios of ethylene, propylene and butylenes in connection with the different needs for these valuable products at different enterprises.
The effect of zirconium concentration on the catalytic properties of a mesoporous high-silica zeolite catalyst selected for the production of ethylene and propylene from methyl alcohol and dimethyl ether formed by the intermolecular dehydration of methyl alcohol was studied (Table 1).
The highest selectivity (50.0-75.2%) for the primary representatives of the unsaturated ethylenic hydrocarbon series, ethylene, propylene, and butylenes, is achieved in the sample modified with a zirconium macrocomplex.
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Table 1.
The effect of the mass fraction of zirconium in the Mg-Zn-Zr/YKS catalyst on its catalytic properties in the conversion of dimethyl ether into ethylene and propylene, the primary representatives of unsaturated ethylenic hydrocarbons
(T = 340 °C, P=0,1 MPa)
Mass fraction of [Zr] in the selected catalyst for the production of ethylene and propylene from dimethyl ether, in % Kdme, % Selective sensitivity,%
CH4 C2= C3= C4= C5= EC2+
0.05 98.7 0.82 20.9 18.9 8.2 3.7 50.8
0.1 99.4 0.22 25.3 19.8 6.8 2,9 47.4
0.2 99.4 0.93 22.4 20.8 7.6 3.2 48.6
In order to study the primary intermediates of the conversion of dimethyl ether, formed by the intermolecular dehydration of methyl alcohol, into ethylene and propylene, the primary representatives of unsaturated ethylenic hydrocarbons, the formation of the main carbon-
carbon bond, i.e., the catalyst selected for the production of ethylene and propylene from methyl alcohol containing zirconium and dimethyl ether formed by the intermolecular dehydration of methyl alcohol, was tested at a temperature of 240 °C and atmospheric pressure.
Table 2.
Dimethyl ether conversion on a Mg-Zn-Zr/YKS catalyst
(P=0.1 MPa; starting mixture: dimethyl ether formed by intermolecular dehydration of 10% methyl alcohol + He, Vo=2000 h'1)
T, °C Kdimethyl ether, % Selective sensitivity,%
CH4 C2= C3= C4= C5= EC2+ MeOH EtOH
240 8.8 1.2 5.9 17.9 0.12 - 24.4 44.2 8.4
270 21.4 1.6 22.2 30.2 0.13 2.4 7.4 36.4 2.9
Figure 1. Dependence of the methyl alcohol/ethyl alcohol ratio on the volume velocity of the initial gas mixture in Mg-Zn-Zr/YKS
(T=270°C; initial mixture: 10% DME+He)
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Table 3.
Methyl alcohol conversion on a Mg-Zn-Zr/YKS catalyst
(P=0.1 MPa; initial mixture: 10% methyl alcohol+30%CO+60%N2; Vq=2000 h-1)
T,°C KMeOH,% Selective sensitivity,%
CH4 C2= C3= C4= C5= EC2+ DME EtOH
240 9.8 1.4 2.9 2.9 - - 2.8 91.6 0.7
270 78.8 12.4 8.6 16.6 - 0.5 38.4 21.8 4.5
The significantly lower ethanol production in the Mg-Zn-Zr/YKS catalyst selected for the production of ethylene and propylene from methyl alcohol and dimethyl ether can be explained by the high activity of the Mg-Zn-Zr/YKS catalyst. With an increase in temperature to 340 °C, the selectivity of the formation of the first representatives of the unsaturated ethylenic series hydrocarbons from dimethyl ether formed by the intermolecular dehydration of methyl alcohol in zirconium-modified samples increased sharply.
The Mg-Zn-Zr/YKS conversion of the dimethyl ether formed by the intermolecular dehydration of methyl alcohol was only 73%, and the selectivity for the first representatives of the unsaturated ethylenic series hydrocarbons EC2=- C4= increased from 39.7 to 87%. In the case of methyl alcohol, the selectivity of the first representatives of the unsaturated ethylenic series hydrocarbons ethylene and propylene with 100% conversion was 57.3%.
Table 4.
Mg-Zn-Zr/YuKS and dimethyl ether conversion
(P=0,1 MPa; Vq=2000 h-1)
Initial mixture T, °C Kdme, % Selective sensitivity,%
CH4 C2= C3= C4-5= EC2+ MeOH EtOH
Dimethyl ether+He 240 1.8 1.1 4.8 14.8 0.8 0.82 79.3 -
270 3.4 0.6 7.4 31.0 1.9 1.34 57.5 1.8
Dimethyl ether+ CO+N 240 0.9 1.2 9.2 29.2 - 8.36 57.2 1.9
270 2.8 0.9 14.3 40.2 - 3.47 42.2 1.9
Table 5.
Conversion of methyl alcohol in Mg-Zn-Zr/YKS
(P=0,1 MPa; Vq=2000 h-1)
Initial mixture T, °C Kdme, % Selective sensitivity,%
CH4 C2= C3= C4-5= EC2+ MeOH EtOH
Methyl alcohols + CO + H2 240 46.4 1.4 - - - traces - 96.9
270 56.2 1.5 traces - - traces - 99.2
The effect of the volume velocity of the initial gas mixture on the catalytic properties of a Mg-Zn-Zr/YKS catalyst with high catalytic activity, selectivity, and productivity in the conversion of dimethyl ether into ethylene and propylene, the primary representatives of unsaturated ethylenic hydrocarbons, was studied. With an increase in the volume velocity from 1000 to 5000 h-1, the dimethyl ether conversion decreased from 96.5 to 40.7%, and the overall selectivity for the primary representatives of unsaturated ethylenic hydrocarbons, ethylene, propylene, and butylenes, increased from 59.0 to 75.5% (shown in Table 6). The amount of alkanes in the reaction products decreases sharply. At the same time, with an increase in the conversion of dimethyl ether formed by the intermolecular dehydration of methyl alcohol (with a decrease in the volumetric consumption rate of the raw material), the ratio of ethylene to propylene increases,
the selectivity for ethylene decreases, and the selectivity for propylene increases. With an increase in the conversion of dimethyl ether formed by the intermolecular dehydration of methyl alcohol, the total yield of ethylene and propylene, the initial representatives of the unsaturated ethylenic hydrocarbon series, also increases, and with an increase in the conversion of dimethyl ether formed by the intermolecular dehydration of methyl alcohol at a conversion of -50% of propylene, the amount of byproducts of the reaction - paraffins with a C2+ content -also increases..
In the conversion of dimethyl ether from the intermolecular dehydration of methyl alcohol, the optimum temperature for the Mg-Zn-Zr/YKS catalyst, which has properties such as high catalytic activity, selectivity, and productivity, is 320-340 °C.
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Table 6.
Effect of reaction temperature on the distribution of dimethyl ether conversion products on a Mg-Zn-Zr/YKS catalyst
(T=340°C, P=0,1 MPa; sampling time 4 hours)
T, °C V0, h-1 Kdme, % Selective sensitivity,%
CH4 C2= C3= C4= C5= EC2+ EC2-C4=
320 500 60 2.3 29.3 35.7 8.4 3.7 20.6 73.4
340 2000 60 2.5 21.0 36.0 11.0 6.0 23.5 68.0
360 10000 60 13.8 14.0 27.8 9.9 6.3 28.2 51.8
Conclusion
Thus, the synthesis of the primary representatives of unsaturated ethylenic hydrocarbons, ethylene and propylene, from dimethyl ether, formed by the intermolecular dehydration of methyl alcohol, over
zirconium-containing mesoporous high-silica zeolite catalysts with high catalytic activity, selectivity, and productivity, increases the high conversion of the raw material and the selectivity (up to 90%) for the formation of the primary representatives of unsaturated ethylenic hydrocarbons, ethylene and propylene.
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