POLYMER RESIN PRODUCTION FROM PYROLYSIS PRODUCTS: PROCESS PARAMETERS AND SOLUBILITY ANALYSIS

ABSTRACT

This study investigates the physico-chemical properties and the potential for producing petroleum polymer resins from secondary oil pyrolysis products - distillates, condensates, and heavy fractions obtained at the Ustyurt gas-chemical complex. Pyrolysis was carried out at temperatures ranging from 120 to 230 °C for 1 to 4 hours. The products were separated into gas, liquid, and resin fractions, and their density, viscosity, thermal stability, and elemental composition were analyzed. The optimal conditions for resin extraction from the heavy fraction were found to be a temperature of 180–200 °C and duration of 3 hours.

АННОТАЦИЯ

В данном исследовании изучены физико-химические свойства и возможность получения нефтяных полимерных смол из вторичных продуктов пиролиза нефти – дистиллятов, конденсатов и тяжелых фракций, полученных на газохимическом комплексе Устюрт. Пиролиз проводился при температуре 120–230 °C в течение 1–4 часов. Продукты разделялись на газовую, жидкую и смолянистую фракции, изучались их плотность, вязкость, термическая устойчивость и элементный состав. По результатам исследования оптимальными условиями выделения смолы из тяжелой фракции признаны температура 180–200 °C и время 3 часа.

Keywords: secondary oil pyrolysis, heavy product, petroleum polymer resins, pyrolysis process, temperature and time parameters, solubility.

Ключевые слова: вторичный пиролиз нефти, тяжелый продукт, нефтяные полимерные смолы, процесс пиролиза, температурный и временной режимы, растворимость.

Introduction. Worldwide, extensive scientific research is being conducted on the pyrolysis process to obtain energy and valuable chemical products through the recycling of plastic and biomass waste. The main focus is on studying the influence of process parameters such as temperature, pressure, time, and heating rate on the pyrolysis products. Most studies emphasize that the efficiency of the pyrolysis process increases with rising temperature and pressure. It has been shown that maintaining the temperature in the range of 500–600°C can ensure a high yield of liquid products [1-5]. At the same time, at higher temperatures, the amount of resin decreases while gas production increases. When analyzing the effects of temperature and reaction time in biomass pyrolysis, an increase in reaction time positively affects the amount of liquid substances, whereas an increase in temperature leads to a decrease in resin yield [6]. Similar trends have been observed in the pyrolysis of plastic waste: increasing temperature and pressure results in higher gas yields, while the yield of liquid oils is higher at elevated temperatures [7]. Moreover, the processing of pyrolysis resins produced at the Ustyurt gas-chemical complex holds particular importance. The heavy fractions formed during oil pyrolysis - resins consist of aromatic, olefinic, dienes, and oxygen-containing compounds, whose organic purification is complex and hinders the production of valuable products [8]. Therefore, reprocessing these resins to obtain energy and high-value substances is a relevant direction [9]. Pyrolysis distillates, condensates, and heavy products are rich in benzene, toluene, styrene, and other aromatic/aliphatic hydrocarbons, offering the potential to produce highly active petroleum polymer resins. Modern research aims to improve the physical and mechanical properties of resins obtained from these fractions [10].

Research methods. Secondary pyrolysis products - distillate, condensate, and resin fractions – were separated and collected. Experiments were conducted in reactors with volumes ranging from 250 to 1000 ml, at temperatures between 120 and 230 °C, under atmospheric pressure, and for durations of 1 to 4 hours. The density of the petroleum pyrolysis resin ranged from 1.05 to 1.15 g/cm³, viscosity from 150 to 300 mm²/s, boiling point from 300 to 380 °C, and thermal stability from 250 to 280 °C. The physico-chemical and compositional properties of the products were determined according to GOST and ISO international standards. Density was measured using GOST 2177-99 and ISO 2811-1 standards with a hydrometer; viscosity was determined by a viscometer in accordance with GOST 5906-79 and ISO 3104; boiling point was established using the distillation method according to GOST 2177-99 and ISO 3405.

Discussion of results. Petroleum pyrolysis resins are important from both energy and chemical perspectives, and their efficient processing allows for the production of high value-added products. The heavy fraction obtained from the Ustyurt gas-chemical complex has a high molecular weight structurally and mainly contains aromatic, aliphatic, heteroatomic, and oxygen-containing compounds. To improve the efficiency of its processing and to scientifically substantiate technological solutions, a detailed study of its physico-chemical properties is required (Figure 1).

Figure 1. Physico-chemical properties of the heavy fraction from the Ustyurt gas-chemical complex

The resin has a density of 1.05-1.15 g/cm³ and a viscosity of 150-300 mm²/s. It contains heavy and high molecular weight hydrocarbons, with a thermal stability range of 250-280 °C, boiling point of 300-380 °C, liquefaction temperature of 120-150 °C, and an energy value of 35-40 MJ/kg.

The composition of organic substances formed as a result of pyrolysis of the secondary heavy fraction (tar) at different temperatures changes significantly depending on the temperature. In general, as the temperature increases, the proportion of lighter, more volatile compounds decreases, while the formation of polycyclic aromatic hydrocarbons and coke increases (Figure 2):

Figure 2. Organic substances released during pyrolysis at different temperatures

Based on the table results, in the temperature range of 250-300 °C, mainly lighter compounds such as phenols, cresols, and monocyclic aromatic hydrocarbons were formed, most of the resin remaining in a liquid state.

Pyrolysis was carried out at temperatures of 250-300 °C, 350-400 °C, and 450-500 °C, and at reaction durations of 2, 4, and 6 hours. The total amount of resin separated was analyzed (Figure 3).

Figure 3. Dependence of the amount and yield of resin separated during pyrolysis on reaction duration at different temperatures

During the process of extracting resin from the secondary TAR product, it was found that the total amount of resin decreases with increasing pyrolysis temperature and reaction duration. The relationship between reaction time and temperature was identified as a critical factor in the pyrolysis process. Specifically, a temperature of 250–300 °C and a reaction time of 2 hours were determined to be the optimal conditions, facilitating the production of high-quality resin products while reducing energy consumption (Figure 4). The process was carried out under both air and inert (oxygen-free) conditions.

Figure 4. Dependence of product yield and purity on reaction duration

From the graph, at a reaction duration of 2 hours, the product yield was 60% in an inert atmosphere and 70% under air conditions.

Additionally, the pyrolysis process was carried out at different times and temperatures, and the results were analyzed. Changes in reaction time and temperature during pyrolysis were found to have a significant impact on the composition of the products, including the yields of gas, liquid, and resin fractions (Figure 5).

The obtained results show that when the process was carried out at temperatures of 120–140 °C, the yield was 21–22%; at 150–170 °C it increased to 30–34%; and at 180–200 °C, the highest yield was observed. However, a decrease in yield was noted at 210–230 °C, where it dropped to 26–28%. These findings confirm that the optimal yield of resin is achieved at a temperature range of 180–200 °C.

Table 1. Yield of pyrolysis products depending on temperature and time (Atmospheric pressure, reaction times: 1 and 2 hours)

Based on the chemical composition and physico-chemical properties of the pyrolysis fractions obtained from the Ustyurt chemical complex, it was determined that the pyrolysis distillate contains benzene, alcohols, and acidic compounds. The pyrolysis condensate consists of aromatic and condensed components and possesses high thermal stability, which offers significant advantages for its modification. The study of the composition of these fractions confirmed the possibility of their chemical modification to produce high-quality petroleum polymer resins.

Experimental results show that the solubility of petroleum polymer resin increases with both temperature and time. In the 70–75 °C range, benzene stands out as an effective solvent, while in the 80–120 °C range, toluene and xylene demonstrate higher efficiency. Over time, solubility increases across all solvents; however, certain solvents like n-heptane maintain a relatively low solubility level.

Therefore, when selecting a solvent, it is essential to strike a balance between solubility, temperature, reaction time, and safety considerations.

The solubility of petroleum polymer resin depends not only on the type of solvent and temperature but also on how it changes over time. In the study, solubility levels were also analyzed at two temperature ranges (70–75°C and 80–120°C) (Table 5).

Table 5. Dependence of solubility on reaction duration

In general, benzene, toluene, and xylenes are considered the most effective solvents for dissolving petroleum polymer resins, provided that proper safety precautions are followed. Although solvents with lower solubility-such as ethyl acetate, butyl acetate, and butanol-1 offer advantages in terms of safety, their effectiveness is limited.

Conclusion. The research results indicate that the physico-chemical properties of the fractions- including thermal stability, molecular weight, and the presence of aromatic and heteroatomic compounds - make them suitable for resin synthesis and modification. Additionally, pyrolysis experiments conducted under both air and inert conditions demonstrated that higher yields were achieved in the presence of air, highlighting the importance of accurately and carefully selecting process parameters.

Solubility analysis of the resins showed the effectiveness of solvents such as benzene, toluene, and xylene. Overall, these findings confirm the potential for obtaining high-quality resins from secondary pyrolysis fractions and support their application in relevant industrial sectors.

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