MODIFICATION OF INORGANIC CATALYSTS USED IN THE THERMOCATALYTIC TREATMENT OF AUTOMOBILE TIRES

АBSTRACT

During the thermal catalytic processing of worn-out transport tires using modified catalysts, the formation of substances that improve its quality in the resulting fuel is achieved. The article discusses the increase in resistance to coking and poisoning due to the use of ACM catalyst in the modification process by adding active substances such as SiO₂, P₂O₅ used in the processing of petroleum products. In addition, the maximum purification of liquid fuels from harmful compounds and their saturation with hydrogen, an increase in the amount of substances that improve the quality of the fuel.

АННОТАЦИЯ

При термокаталитической переработке пришедших в негодность транспортных шин с использованием модифицированных катализаторов позволяет достигается образование веществ, улучшающих его качество в полученном топливе. В статье рассматривается повышение стойкости к закоксовыванию и отравлению за счет применения в процессе модификации катализатора АCМ, путем добавления активных веществ, таких как SiO₂, P₂O₅, используемого при переработке нефтепродуктов. Кроме того, максимальная очистка жидких топлив от вредных соединений и насыщение их водородом, увеличение количества веществ, улучшающих качество топлива.

Ключевые слова: модификация, термокаталитический пиролиз, неорганический катализатор, качественное топливо.

Keywords: modification, thermal catalytic pyrolysis, inorganic catalyst, high-quality fuel.

It is known that oil refineries, in particular Feghana Oil refinery  L 35-11/300, LCH 35-11/600, use Al-Co-Mo (ACM) catalysts, such as Hydrodesulphization devices, to purify petroleum products from harmful compounds (heterocyclic compounds S, N₂, O₂). When using this type, the catalysts are removed after 5-7 years as process waste. Usually, catalysts do not give the expected result if the active surface decreases and the reaction rate decreases during the process. After reducing the active surface, the catalysts are replaced with new ones. Since Al-Co-Mo catalysts are used in refineries to purify light fractions, their active surface must always be active. Since oil refineries do not have new technologies based on the processing of spent catalysts, they are not recycled and concentrated in the form of solid industrial waste. It is possible to recycle catalysts that consist of unique elements of this type. The main reasons that render catalysts unusable are the deposition of coke on their active surface, poisoning of S, N₂, O₂ under the action of heterocyclic compounds[3].

Al-Co-Mo catalysts formed as waste are burned in the reactor at a temperature of 400-500 °C, and heated water vapor is supplied under pressure. In this case, coke and other compounds trapped in the pores of the catalyst are removed. When using this process, the efficiency of the catalyst is not exceeded. Since such regeneration methods are used continuously in the Feghana Oil refinery   and are used to reuse the catalyst. After repeated regenerations, the activity of the catalysts decreases, and the purification process decreases compared to normal parameters.

To restore the activity, the catalyst is processed. The procedure is performed in the following order.

The exhaust gas catalyst is crushed in a mill. The coking part is separated from the crushed mixture. To bring the amount of active ingredients in the mixture to normal, pure СоО, МоО₃  oxides are added,. SiO₂ is added to the crushed catalyst to improve its viscosity and solidification. After that, the mixture is prepared and pressed using a press without high catalyst pressure and re-poured into a spherical shape. Since it does not compress under high pressure, its density is normal (0.83-0.84 g/sm³). The finished catalyst, which is brought to a spherical state, is modified with a solution of phosphonic acid. After drying, the composition of P₂O₅ 1.6-1.8% remains on the surface of the catalyst.

This method increases the resistance of ACMS catalysts modified with active ingredients to coking and poisoning. In addition, the maximum purification of liquid fuel from harmful compounds is achieved, as well as hydrogen saturation, an increase in the content of substances that improve fuel quality.

Picture 1. Scheme of waste catalyst utilization

The efficiency of the process is also influenced by the particle size of the catalyst and the methods of its preparation. Trivalent catalysts are mainly used.

- in the form of tablets;

- spherical;

- in the form of an extrudate (cylindrical)[1].

According to the study, the best of the forms in which the active surface of the ACMS catalyst is most active and resistant to heating and external influences (exposure to toxic compounds) is spherical.

Table

Indicators of catalysts by structure

As can be seen from the table, the form in which the active surface is most active in the production of the ACMS catalyst is spherical catalysts. These catalysts are deposited in the highly excitable reactor layer. Due to the addition of SiO₂ to its composition, the catalyst has a high stagnation of water vapor and toxic coking compounds.

The following technological indicators were studied using a recycled ACMS catalyst:

- the nature and composition of the catalyst;

- quantitative composition of the catalyst;

- the time of the process;

- tire dispersion;

- temperature and pressure of the process.

The nature and selectivity of the ACMS catalyst have been studied by adding various amounts of SiO2 to the catalyst composition to improve its compatibility. The following experimental test was conducted in order to determine whether the recycled catalyst is resistant to coking and poisoning.

During the test study, SiO₂ was added to the total mass in various amounts to increase the resistance of the ACM catalyst to coking and poisoning. In this case, the catalyst in relation to its total mass is 4 %, 5 %, 6 %, 7 %, 8 %, 9 %, 10 %, 11 % they were added in such an amount that, under homogeneous conditions, the type of fuel was taken in equal quantities[2, 4].

Picture 2.The ratio of SiO₂ addition to ACM and the amount of accumulated compounds harmful to the catalyst  

The fuels were tested in 8 samples. After completion of each process, the catalysts contained in the sample were weighed on analytical scales. The results obtained are shown in Picture 2. The results of the analysis showed that in the selected samples there was a slight accumulation of coke and harmful compounds in SiO₂ - up to 9%.

Table 2

The number of active ingredients and distribution carriers in some catalysts

As a result of the study, it was proved that when the amounts of active substances contained in catalysts differ in relation to mass, many reactions can be observed that proceed in different ways, depending on the mass ratio of active substances, the nature of the catalyst, viscosity, selectivity, and influence on parameters.

References:

1. И.А. Баканев «Разработка каталитической системы гидрооблагораживания вакуумного газойля», Министерство образования и науки Российской Федерации Федеральное государственное бюджетное образовательное учреждение высшего образования «Российский государственный университет нефти и газа (национальный исследовательский университет) имени И.М. Губкина» Диссертация, Москва 2021 г.
2. G.R. Mirzakulov, F.M. Yusupov International Journal Of Advanced Research in Science, Engineering and Technology VOLUME 7, ISSUE 8, August 2020 ISSN: 2350 0328 (- P 14583-14587 )
3. G.R. Mirzakulov, F.M.Yusupov Scientific –technical journal of FerPI 2020 . Том 24 . спец. вып. № 1. Часть 1 ISSN 2181-7200 (80-85 бетлар)
4. G.R. Mirzakulov, F.M. Yusupov, G.M. Mirzakulova Scientific  – technical journal of FerPI  2020 Том 24 . спец. вып. № 1. ISSN 2181-7200 (P 71-76)