CC BY
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ISSN 2522-1841 (Online) ISSN 0005-2531 (Print)
AZERBAIJAN CHEMICAL JOURNAL № 4 2022
83
UDC 665.6/7:502.171;665.6/7:658.567
RESEARCH OF CATALYTIC PROCESSING OF LIGHT PYROLYSIS RESIN -BY-PRODUCT OF ETHYLENE PRODUCTION
F.M.Sadigov, G.N.Haciyev, Sh.D.Aliyeva, I.Q.Mamedova, G.H.Hasan-zadeh,
E.T.Melikova, N.S.Sadigova
M.Nagiyev Institute of Catalysis and Inorganic Chemistry, NAS of Azerbaijan
E_colifefutur_e@mail.ru
Received 18.05.2022 Accepted 29.06.2022
The quantitative and qualitative composition of the light pyrolysis resin was preliminarily studied on an Agilent Technologies 7820A gas chromatograph, and the amount of benzene and its mono-, di-, and trial-kyl derivatives was determined. By catalytic and thermal treatment, the mass fraction of benzene in light pyrolysis resin was increased from 37.94 to 47.38%. The benzene-toluene fraction was separated by rectification and the presence of petroleum-polymer resin in the residue was investigated. Unlike traditional methods, the catalyst is not ready for the process, it is synthesized directly based on the system's components- alkyl benzene derivatives during the process. At normal atmospheric pressure, at low temperatures and for a short period, a light pyrolysis resin was processed with a cheaper catalyst. Thus, less capital, less energy consumption, and less metal content in the process reduce the cost of benzene and toluene. At the same time, Al complex catalyst stimulated oligomerization and polymerization processes in the system, causing the formation of petroleum-polymer resin in the residue. In this way, the mass percentage of valuable components (benzene and toluene) was increased and the residue was enriched with petroleumpolymer resin.
Keywords: light pyrolysis resin, benzene, toluene, polymer resin.
doi.org/10.32 73 7/0005-2531-2022-4-83-88 Introduction
The main products in the pyrolysis process in ethylene production facilities are ethylene and propylene. By-products are light and heavy resins and makeup 30-40% of the total product. Depending on the type of raw materials and pyrolysis regime in ethylene-propylene plants, the quantitative and qualitative composition of light resin varies. Most of the composition of light resin is aromatic hydrocarbons [1, 2].
Pyrolysis distillate contains mainly arenes and olefins with a carbon content of 6-12. Olefins account for 23.7% and arenes for 67.18%. In addition, there are alkanes, dienes, and cycloal-kanes [3, 4].
Petrochemical plants consist of several interconnected technological blocks. Although oil refining is the backbone of the industry, it is the most energy-intensive. In the Russian Federation, Nizhny Novgorod, Sibur Kstovo LLC benzene production is carried out in 4 interrelated stages (benzene-toluene-xylene fractionation, hydrogenation, hydrodesulfurization, hydrothermal process) [5].
trimethylbenzene, Al-complex catalyst, petroleum-
In general, the deepening of refining processes and expanding the range of products is a leading force in the modern petrochemical industry. Pyrolysis of hydrocarbon feedstocks, especially primary gasoline fractions and large fractions of light hydrocarbons, is a key process that allows the production of much-needed monomers such as ethylene and propylene. The total capacity of pyrolysis plants in the world is more than 130 million tons. Despite ongoing work to improve the design of pyrolysis furnaces and optimize regimes, the process of obtaining low olefins is accompanied by the formation of significant amounts of by-products, the use of which poses a serious technical and economic problem and reduces production profitability. The development of technologically efficient and cost-effective methods for the use of liquid pyrolysis products is still an unfinished task.
The growing demand for most aromatic hydrocarbons is directly related to the development of the petrochemical industry. Ways of using liquid pyrolysis products formed during the production of low olefins are being investigated [6, 7].
In this regard, the efficient processing of light resin is important today. Exploring ways to address this issue is relevant for oil-rich countries (including Azerbaijan). Benzene from the processing of light pyrolysis resin accounts for 4550% of benzene produced worldwide. All over the world, thermal and catalytic hydrodealky-lation of benzene-toluene-xylene fraction in lightly hydrostabilized and hydrotreated pyro-lysis resins, which require large energy, material and capital expenditures, are used as a solution to this problem, and valuable catalysts such as Pt, Pd are used [ 8-12].
Hydrogenation of alkadienes in light py-rolysis resin fractions and purification of light resin is carried out in active palladium-centred catalytic systems [13].
The processing of light pyrolysis resin with toluene-based Al-complex catalyst was studied and the mass fraction of benzene was increased from 35 to 41%, benzene was obtained at 99.1% purity using the freezing method and the optimal catalyst amount for a maximum increase of benzene was studied. Thus, the maximum efficiency of the catalyst was 3.5%. The richness of the residue with petroleum-polymer resin was determined. In general, aluminum chloride catalyst is used in many studies in the processes of alkylation and dealkylation of aromatic hydrocarbons [14, 15].
In addition, research is being conducted to obtain paints and varnishes from pyrolysis resins.
Studies show that catalytic systems synthesized with aluminium are also highly active in the oligomerization of unsaturated hydrocarbons in light resins [16]. This makes it important to study ways to produce lightweight resin to petroleum-polymer resins.
Fractions of light pyrolysis resin which is rich with unsaturated hydrocarbons (styrene, vinyl toluene, etc.) are mainly used in the production of petroleum-polymer resins. One of the various processing methods of light pyrolysis resin is the production of petroleum-polymer resins, which are an indispensable product to reduce the consumption of rare, valuable, and
natural resins such as vegetable oils, rosin, wood pyrogen, and inden-camaron [17-19].
The main raw material base of petroleum-polymer resins is the liquid by-product (light resin) formed during pyrolysis in the production of ethylene-propylene. The boiling temperature of light pyrolysis resin is 30-2000C and contains C6-C9 aromatic hydrocarbons. Production of petroleum-polymer resin is carried out by applying thermal, catalytic and radical oligomerization processes. Petroleum-polymer resins are used in the manufacture of paints, printing inks, adhesives, sealants, plastics, and rubbers [20].
The main purpose is to complexly process light pyrolysis resin - to increase the mass fraction of aromatic hydrocarbons by the action of Al-complex catalyst, to separate the target products (benzene, toluene) by rectification, and to study the methods of converting the residue into petroleum resin.
Experimental part
A series of analyzes on gas chromatograph Agilent technologies 7820A (column HP5, length 30 m, diameter 3.210-4, active phase density 2.5 10-7) show that the light resin contains 34-37% benzene, 14-17% toluene and other aromatic hydrocarbons - styrene, ethyl-benzene, xylenes, trimethylbenzene. In general, 70-80% of light pyrolysis resin is aromatic hydrocarbons, and the rest is alkanes, cyclo-alkanes, alkenes and other saturated and unsa-turated hydrocarbons. The composition of the light resin is shown in Table 1.
Table 1. Hydrocarbon content of light resin
Hydrocarbons Mass fraction of substance in light resin,%
Hexan 0.42
Benzene 37.94
Toluene 17.73
Ethylbenzene 1.00
Xylene 3.19
Styrol 7.18
1,3,5 trimethylbenzene 2.02
1,2,4 trimethylbenzene 6.89
1,2,3 trimethylbenzene 2.24
Hydrocarbons above C9 21.39
Total 100
RESEARCH OF CATALYTIC PROCESSING OF LIGHT PYROLYSIS.
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In the current research, the light resin was catalytically and thermally processed and rectified. The increase in benzene in the light resin and the presence of petroleum-polymer resin in the residue were investigated. Thus, in previous experiments, the Al complex catalyst was synthesized and delivered to the system, while in these experiments, the catalyst was synthesized directly in the system. A schematic description of the processing unit with block diagrams is shown in Figure 1.
4
CD 2.
Fig. 1. Block diagram description of the device for catalytic processing of light pyrolysis resin: 1 - heater, 2 - reactor, 3 - mixer, 4 - refrigerator, 5 - aluminum scrap, 6 -NaCl, 7 - sulfuric acid (solid), 8 - gas pipe (HCl).
For the experiment, 240 g (300 ml) of light resin was taken and placed in a 3-necked flask with a thermometer, a condenser, a mixer and a heater, and the experiment began. Thus,
the system includes HCl gas and Al scrap (length 5 mm, width 1 mm, thickness 1 mm). The process is carried out by directly synthesizing an Al complex catalyst in light resin. HCl gas is obtained from the interaction of NaCl and solid H2SO4 acid and is introduced into the system during the process, and reacts with Al to form a complex catalyst.
2NaCl + H2SO4 = Na2SO4+2HCl
First, the optimal time and temperature for the maximum increase of benzene were determined by conducting experiments at a constant amount of aluminum at different times and different temperatures. It was studied that the contact time of 4 hours and the temperature of 800C is the optimal indicators of this experiment. Then, experiments were performed for different amounts of aluminum, and the dependence of the maximum increase in the amount of benzene in the process on the amount of aluminum was studied. Thus, in practice, the dynamics of benzene growth in the amount of more than 1.5 grams of aluminum began to stabilize. In experiments, the contact time and temperature were kept stable. T=4 hours, t=800C. Light resin samples were analyzed on Agilent technologies 7820A gas chromatography and are shown in Table 2. As can be seen from the table, there is an increase in the amount of benzene, toluene, xylene, and a decrease in the amount of styrene and trimethylbenzene. Stage IV is the stage of maximum increase of benzene. Consumption of aluminum at this stage was calculated as 1.5 grams.
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1
Table 2. Composition of samples
Hydrocarbons Light resin LR+0.26 gr Al LR+1 gr Al LR+1.26 gr Al LR+1.5 gr Al LR+2 gr Al LR+2.5 gr Al
Hexan 0.42 0.41 0.39 0.29 0.21 0.18 0.16
Benzene 37.94 41.03 46.13 46.32 47.38 47.22 47.07
Toluene 17.73 19.23 21.71 22.42 23.02 23.88 24.10
Ethylbenzene 1.00 1.31 1.54 1.54 1.54 1.58 1.60
Xylene 3.19 3.45 3.84 3.99 4.00 4.00 4.06
Styrol 7.18 7.01 5.08 4.72 3.22 2.06 2.39
1,3,5 trimethylbenzene 2.02 0.78 0.99 0.76 0.73 0.49 0.25
1,2,4 trimethylbenzene 6.89 5.95 0.33 0.28 0.25 0.00 0.00
1,2,3 trimethylbenzene 2.24 0.36 0.20 0.14 0.08 0.03 0.02
Unidentified 21.39 20.47 19.79 19.52 19.57 20.56 20.35
Total 100 100 100 100 100 100 100
A maximum increase of benzene in the amount of 1.5 g of aluminum is observed and continues to decrease, while toluene continues to increase. The dependence of the change in the number of aromatic hydrocarbons on the amount of aluminum is given in Figure 2.
Fig. 2. Dependence of increase and decrease dynamics of aromatic hydrocarbons on the amount of aluminum.
Thus, the optimal ratio of aluminum and light resin is 1:167. This corresponds to 0.6%. In general, the increase in benzene content was 24.8%. As can be seen from Table 1, up to 1.5 g of aluminum is dealkylated, trimethyl benzenes are dealkylated and converted to benzene, but more than 1.5 g of aluminum benzene decreases and toluene increases, excess alkylation occurs and benzene is converted to toluene. The toluene-based Al complex catalyst formed in the system undergoes both alkylation and dealkyla-tion processes, but in this experiment, it was determined that a 0.6% mixture of aluminum in light pyrolysis resin is the upper limit of the dealkylation process. The equation of mass dependence of toluene on the amount of catalyst for the process is
y=25.92-7.53e-078*x;
and degree of reliability is 0.997.
The equation of mass dependence of benzene on the amount of catalyst for the process is
y=47.54-9.77e178*x; and degree of reliability is 0.992.
In the next stage, the catalyst was rectified and the benzene-toluene fraction was separated. The condensate was separated by expelling to 1150C. The presence of oil-polymer resin in the residue was determined. Thus, the obtained residue was thermally processed and a solid, bright, dark brown viscous substance was obtained, and research is underway in this direction. In the future, ways to use the residue more efficiently can be explored and researched.
Results and discussion
In this experiment, the catalyst is not readily supplied to the system and is directly synthesized and obtained during the process. The process is carried out at normal atmospheric pressure, for a short time (4 hours) and at a low temperature (800C). This is efficient in terms of both energy and capital consumption. Cheaper catalysts are used instead of expensive catalysts. This catalyst also provides an opportunity to increase the mass fraction of several components and to conduct research that will allow more efficient use of the residue. It was studied that Al complex catalyst in light pyrolysis resin stimulates both alkylation and dealkylation processes, and the optimal amount of aluminum (0.6%) was determined for the dealkylation process. It is assumed that the catalyst in this experiment leads to the conversion of alkyl benzene derivatives (trimethyl benzene) to benzene in light pyrolysis resin, which increases the mass fraction of benzene. At the same time, it can be assumed that this catalyst stimulates oligomerization and polymerization processes in the system and the residue is enriched with oil-polymer resin when it is thermally processed.
Conclusions
The aluminum complex catalyst increases the mass fraction of benzene from 37.94% to 47.38% in a 0.6% concentration of aluminum in a light resin.
Due to low energy, low metal content, and low capital consumption, the proposed technology is more efficient compared to research in this area.
The fact that the residue is rich in petroleum-polymer resin shows that it is possible to
RESEARCH OF CATALYTIC PROCESSING OF LIGHT PYROLYSIS
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process light resin into paints and varnishes by deepening and expanding research in this area.
Unlike traditional methods, the catalyst is not readily supplied to the system. It is synthesized during the process and enters the reaction. This makes the processing more efficient.
The catalyst affects the process in two ways. Increases benzene, stimulates oligomeri-zation and polymerization processes, and synthesizes petro-polymer resin in the system.
References
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ETÍLEN iSTEHSALININ YAN MOHSULU - PÍROLÍZÍN YÜNGÜL QOTRANININ KATALÍTÍK
EMALI PROSESLORlNÍN TODQÍQÍ
F.M.Sadiqov, Q. N.Haciyev, §.D.0liyeva, LQ.Mammadova, G.H.Hasan-zad3, E.T.Malikova, N.S.Sadiqova
Pirolizin yüngül qatraninin kamiyyat va keyfiyyat tarkibi Agilent Technologies 7820 A qaz xromatoqrafi ib tadqiq olunmuç va tarkibinda benzolun va onun mono-, di- va trialkil töramalarinin miqdari müayyan edilmiçdir. Katalitik va termik emal edilarak, pirolizin yüngül qatraninda benzolun kütla faizi 37.94%-dan 47.38%-a qadar toluolun kütla faizi 17.73%-dan 24.10%-a yûksaldilmiçdir. Rektifikasiya olunaraq benzol-toluol fraksiyasi aynlmiç va qaliqda neft-polimer qatraninin mövcudlugu tadqiq olunmuçdur. ônanavi üsullardan farqli olaraq, katalizator prosesa hazir çakilda verilmamiç, sistemin öz komponentlari- alkil benzol töramalari asasinda birbaça sintez olunmuç va proses zamani sarf olunmuçdur. Adi atmosfer tazyiqinda, yüksak olmayan temperaturda va qisa zaman kasiyinda, daha ucuz katalizatorla pirolizin yüngül qatrani emal edilmiçdir. Bela ki, daha az kapital, daha az enerji sarfi, prosesin az metaltutumlu olmasi benzolun va toluolun maya dayarini açagi salir. Eyni zamanda Al kompleks katalizatoru sistemda oliqomerlaçma va polimerlaçma proseslarina takan verarak qaliqda neft-polimer qatraninin amala galmasina sabab olmuçdur. Bu üsulla ham qiymatli komponentlarin (benzol va toluol) kütla faizi yûksaldilmiç va ham da qaliq neft-polimer qatraniyla zanginlaçdirilmiçdir.
Açar sözlzr: pirolizin yüngül q3tram, benzol, toluol, trimetilbenzollar, Al kompleks katalizatoru, neft-polimer q3tram.
ИССЛЕДОВАНИЕ КАТАЛИТИЧЕСКОЙ ПЕРЕРАБОТКИ ЛЕГКОЙ ПИРОЛИЗНОЙ СМОЛЫ -ПОБОЧНЫЙ ПРОДУКТ ПРОИЗВОДСТВА ЭТИЛЕНА
Ф.М.Садыгов, Г.Н.Гаджиев, Ш.Д.Алиева, И.Г.Мамедова, Г.Г.Гасан-заде, Э.Т.Меликова, Н.С.Садыгова
Количественный и качественный состав легкой пиролизной смолы был исследован на газовом хроматографе Agilent Technologies 7820 A и было определено содержание бензола и его моно-, ди- и триалкилпроизводных. Путем каталитической и термической обработки в легкой пиролизной смоле массовая доля бензола увеличена с 37.94 до 47.38%, толуола с 17.763 до 24.10%. Ректифицирован и отделена бензол-толуольная фракция и исследовано наличие нефтеполимерной смолы в остатке. В отличие от традиционных методов, катализатор не подается в систему, он синтезируется непосредственно на основе собственного компонента системы -производные алкил бензола, и используется в процессе. При нормальном атмосферном давлении, низкой температуре и короткое время легкая пиролизная смола перерабатывалась с катализатором низкой себестоимости. Таким образом, меньший капитал, меньшее потребление энергии, меньшее содержание металла в процессе снижает стоимость бензола и толуола. В то же время комплексный Al-катализатор стимулировал процессы олигомеризации и полимеризации в системе, а в остатке образовывалась нефте-полимерная смола. Таким образом, увеличилась массовая доля ценных компонентов (бензола и толуола), а также увеличилось количество нефте-полимерной смолы в остатке.
Ключевые слова: легкая пиролизная смола, бензол, толуол, триметилбензолы, алюминиевый комплексный катализатор на основе толуола, нефтеполимерная смола.
