A method of heating ethylene tar

Abstract

The application discloses a method for heating ethylene tar, which is characterized in that a mixture containing ethylene tar and nano-molybdenum disulfide is mixed with hydrogen, and then the ethylene tar is heated to a temperature T; the temperature T is less than or equal to 420 DEG C. The method can heat the ethylene tar to 420 DEG C, and the ethylene tar does not decompose and cokes obviously, and can meet the heating requirements of further distillation separation or hydrofining, hydrotreating and other reaction processes. The heating mode overcomes the limitations of the existing heating mode of the ethylene tar by adding trace nano-molybdenum disulfide and hydrogen, has strong practicability, and has a positive effect on the comprehensive utilization and deep processing of the ethylene tar by using the technology.

Description

Technical Field

[0001] This application relates to a method for heating ethylene tar to increase its temperature for further separation or reaction, belonging to the fields of petrochemicals and fine chemicals. Background Technology

[0002] Ethylene tar, also known as ethylene cracking tar, is a byproduct obtained from the high-temperature condensation of feedstock and products during the steam cracking process of ethylene. It typically has a boiling range above 210℃, a low initial boiling point, a high final boiling point, and relatively high density and viscosity. The main components of ethylene tar are aromatics, primarily a mixture of bicyclic or polycyclic aromatic hydrocarbons, making it a good raw material for extracting high-value-added aromatic fine chemical products. However, currently in China, ethylene tar is mainly used for primary applications such as fuel oil and carbon black production, failing to fully realize its resource value.

[0003] The main reason for this is that ethylene tar has a high content of unsaturated components, high polymerizability, and poor thermal stability. When heated, it undergoes a condensation reaction, which intensifies with further increases in temperature, eventually leading to decomposition and coking. Separating ethylene tar, such as through distillation, or processing it through reactions, such as hydrogenation, requires heating to reach the necessary temperatures. Due to its thermal decomposition and coking characteristics, excessively high heating temperatures or prolonged heating times will cause coking, leading to blockages in equipment such as furnaces, distillation columns, and reactors, making continuous separation or reaction processing impossible.

[0004] The easily decomposed and coking properties of ethylene tar are also reflected in its property determination procedures. For example, the national standard GB / T 9581-2011 "Carbon Black Raw Material Ethylene Tar" stipulates that the distillation yield of carbon black raw material ethylene tar before 210℃ (dry basis, volume fraction) should be ≤10%, and the total oil yield should be ≥70%. The reason for the limited total oil yield is that when using the atmospheric distillation range determination method specified in GB / T 9581-2011, "National Standard GB / T 18255-2022 "Determination of Distillation Range of Coking Slurry Products," the residual ethylene tar in the distillation flask always decomposes near the distillation temperature of 350℃, generating a large amount of coke residue at the bottom of the flask, making it impossible to continue the distillation experiment.

[0005] Basic research results also confirm this instability of ethylene tar. For example, the study "Structural Analysis and Pyrolysis Behavior of Ethylene Residue Oil" (Acta Petrolei Sinica (Petroleum Processing). 2014, 30(06)) found that when the temperature is 320 and 350℃, the thermal conversion of ethylene residue oil is mainly cracking reaction, with a low conversion rate of condensation reaction, and the products are mainly light oil and gas; while at the temperature of 420℃, the condensation reaction intensifies and solid coke is generated; the paper proposed that it is necessary to introduce N2 protection when thermally processing ethylene residue oil.

[0006] Numerous technological developments have recently addressed the challenges of heating ethylene tar. These efforts include distillation to separate aromatic chemicals, delayed coking to convert into light oils and coke, and hydrorefining to produce cleaner oils and chemicals.

[0007] The study "Distillation Separation and Gas Chromatography-Mass Spectrometry Analysis of Fushun Ethylene Tar" (Applied Chemistry, 2018, 35(06)) found that when the distillation temperature is >280℃, the liquid phase temperature reaches above 350℃, and ethylene tar undergoes a chemical reaction, increasing the tendency to coke and produce carbon. Therefore, this study only separated 12 fractions of Fushun ethylene tar at atmospheric pressure by cutting the fraction below 280℃, and did not separate higher fractions. The study "Research on Pre-enrichment Technology of Naphthalene-based Aromatic Hydrocarbons in Ethylene Tar" (Petroleum and Natural Gas Chemical Industry, 2021, 50(05)) points out that using distillation technology to pre-enrich naphthalene-based aromatic hydrocarbons in ethylene tar is problematic because ethylene tar contains components that are prone to polymerization and coking, causing scaling and blockage in the distillation column. This leads to reduced throughput and separation efficiency, resulting in short process cycles or even shutdowns. Therefore, this study developed a highly selective composite extractant to extract and separate ethylene tar feedstock under mild conditions of 30-70℃, removing easily polymerizable and scaling active components, thereby achieving efficient pre-enrichment of high-value-added bicyclic naphthalene-based aromatic hydrocarbon components. The study "Research on Comprehensive Utilization of Ethylene Cracking Tar" (Ethylene Industry, 2012, 24(04)) proposes using conventional distillation methods to separate ethylene tar, with atmospheric distillation controlling the liquid phase temperature to no higher than 300℃ and vacuum distillation controlling the liquid phase temperature to 280℃. Analysis of these results shows that even in conventional distillation operations, the heating temperature of ethylene tar cannot exceed 300°C, and extraction operations must also be performed under low temperature and mild conditions. The coking of ethylene tar due to heat limits its deep separation and affects the full utilization of resources.

[0008] Delayed coking itself generates coke within the reactor, and the feedstock can be heavy oil or residual oil. Although delayed coking has relatively low requirements for the quality of the feedstock, ethylene tar, when used directly as a coking feedstock, will coke in the heat exchanger and furnace. Therefore, current efforts are focused on blending a portion of ethylene tar into delayed coking. The study "The Influence of Blending Ethylene Tar on the Coking Performance of Vacuum Residue" (Modern Chemical Industry, 2023, 52(03)) found that compared with vacuum residue, ethylene tar has a tendency to coke easily at low temperatures and in a short time. After blending ethylene tar into vacuum residue, the coking time is significantly earlier than that of the pure vacuum residue system. In industrial plants, this may manifest as coking during the heat exchange process of the feedstock and coking in the furnace tubes of the furnace, affecting the operating cycle of the coking plant. The study "Feasibility of Delayed Coking Processing of Ethylene Crack Tar" (Refining and Chemical Engineering, 2023, 34(03)) found that ethylene tar begins to lose weight after reaching 200℃, and its stability before 300℃ is significantly worse than that of catalytic slurry oil and vacuum residue. When ethylene crack tar is used as feedstock in delayed coking units, due to its high content of unsaturated components and the presence of some asphaltenes, it undergoes partial dehydrogenation and condensation at high temperatures to produce coke or macromolecular polymers, which causes the coking temperature of the unit to be advanced, resulting in an accelerated coking rate in heat exchangers and furnace tubes. The study proposed that in order for the coking unit to successfully blend crack tar, it is necessary to solve the coking problem before 300℃, for example, by adding stabilizers and solvents before heating to keep the feedstock stable when entering the feedstock heat exchange system of the coking unit. However, the study did not specify which stabilizers and solvents to use. At the same time, the study also reported that the highest blending ratio of ethylene tar in delayed coking at Lanzhou Petrochemical can currently only reach 10%. Patent CN106609145A, "Pretreatment Process of Ethylene Cracking Tar as Delayed Coking Feedstock," provides a pretreatment process for ethylene cracking tar as delayed coking feedstock, along with a complete set of process conditions. This method mixes ethylene cracking tar, ethylene cracking tar stabilizer, vacuum residue, and heavy oil pitch sol-gel additive in a specific ratio and procedure to obtain "sol-gel heavy oil," which serves as the delayed coking feedstock. This addresses the problems in existing coking processes, such as accelerated and aggravated scaling and coking in heat exchange systems, pipelines, and heating furnace tubes, severely impacting the normal operation and operating cycle of delayed coking units. However, this patent does not disclose the composition or components of the "ethylene cracking tar stabilizer" and the "heavy oil pitch sol-gel additive." The paper "Experiment and Evaluation of Processing Benefits of Delayed Coking Processing of Ethylene Cracking Tar" (Petrochemical Technology and Economy, 2020, 36(06)) conducted a coking test on the furnace tubes of the heating furnace. When the temperature of the heating furnace tubes fed with ethylene tar reached 380-407℃, coking completely blocked the thermocouples at the bottom of the heating furnace tubes and the bend of the oil transfer line connecting the coke tower, forcing the test to stop. The evaluation results showed that the stable blending of ethylene cracking heavy oil in the delayed coking unit requires the addition of supporting stabilizers, solvent injection facilities, mixing equipment and corresponding processes, resulting in negative benefits from the delayed coking process of ethylene tar.The above techno-economic analysis shows that, due to the difficulty in heating ethylene tar, even partial blending is not feasible.

[0009] The development of ethylene tar hydrorefining processes also encountered difficulties in heating the raw materials. The paper "Development and Economic Analysis of Ethylene Tar Hydrogenation to Aromatics Technology" (Liaoning Chemical Industry, 2021, 50(12)) reported a three-stage hydrogenation technology for ethylene tar to aromatics, addressing the issue that ethylene tar, due to its high polymerizability, cannot be directly used in chemical processes. The process involves first selectively hydrogenating the polymeric components from ethylene tar at low temperatures, followed by high-temperature hydrogenation refining. The inlet temperatures for the three stages of hydrogenation were 100, 250, and 350°C, with hydrogen-to-oil ratios (volume ratios) around 500 for each stage. The economic analysis of this study indicates that the process flow is slightly long, requiring three hydrogenation reactions and a relatively large number of equipment. The hydrogenation process developed in "Research on Hydrogenation Process of Ethylene Tar Full Fraction" (Guangzhou Chemical Industry, 2017, 45(21)) employs a two-stage hydrogenation process, with the first and second reaction temperatures at 150 and 250°C, respectively, and a hydrogen-to-oil volume ratio of 800. The study "Exploratory Research on Ethylene Tar Fluidized Bed Hydrogenation" (Refining Technology and Engineering, 2020, 50(12)) found that ethylene tar can enter the reactor under cold feed conditions. The ethylene tar entering the reactor will be rapidly diluted, dispersed and heated by hot hydrogen and catalyst, and then undergo hydrogenation reaction, thus avoiding coking of ethylene tar before entering the reactor. Although this cold feed method can solve the problem of coking of ethylene tar feed to a certain extent, heat exchange between product and feedstock is a commonly used energy optimization method in chemical processes. Therefore, cold feed is not conducive to energy management and energy-saving operation of the unit. The paper "Operational Analysis of Ethylene Tar Blending in Slurry Bed Residue Hydrotreating Unit" (Petroleum Refining and Chemical Engineering, 2023, 54(09)) conducted an experiment on blending ethylene tar in a slurry bed residue hydrotreating unit using an imported industrial slurry bed residue hydrotreating unit. The maximum blending ratio of ethylene tar was 4%. The conclusion was that "a high blending ratio will affect the properties of the mixed feed, thereby affecting the operation of the mixed feed pump, and at the same time causing a deterioration in the backmixing effect in the reactor. If the blending ratio is further increased, it may have an adverse effect on the operation of the equipment." In summary, existing ethylene tar hydrorefining processes, in order to avoid the problem of feed coking, either use a low reaction temperature, which will lead to insufficient hydrorefining depth; or use low-temperature feed, which will reduce the energy utilization rate of the system; or use multi-stage hydrotreating, which will increase the process cost; or use small-scale blending, which cannot be used on a large scale.

[0010] Therefore, developing a method for heating ethylene tar to increase its temperature and facilitate further separation or reaction processing is a pressing technical problem that needs to be solved in the utilization of ethylene tar. Solving this problem is of great significance for the full and rational utilization of ethylene tar resources and for improving the economic efficiency of the petrochemical industry. Summary of the Invention

[0011] According to one aspect of this application, a method for heating ethylene tar is provided to facilitate subsequent distillation, hydrorefining, or hydrogenation processing of the ethylene tar. This method involves adding 50-200 ppm of nano-molybdenum disulfide to the ethylene tar and mixing it with 1-10 times the volume of hydrogen (under standard conditions). This heats the ethylene tar to 420°C without significant decomposition or coking, meeting the heating requirements for further distillation, hydrorefining, or hydrogenation processing. This heating method, by adding trace amounts of nano-molybdenum disulfide and hydrogen, overcomes the limitations of existing ethylene tar heating methods, is highly practical, and its application has positive effects on the comprehensive utilization and deep processing of ethylene tar.

[0012] The method for heating ethylene tar is characterized in that a mixture containing ethylene tar and nano-molybdenum disulfide is mixed with hydrogen gas, and then the ethylene tar is heated to a temperature T.

[0013] The temperature T ≤ 420℃.

[0014] Optionally, in the mixture containing ethylene tar and nano-molybdenum disulfide, the concentration of nano-molybdenum disulfide is 50 to 200 ppm.

[0015] Preferably, in the mixture containing ethylene tar and nano-molybdenum disulfide, the concentration of nano-molybdenum disulfide is 50-120 ppm.

[0016] Preferably, the morphology of the nano-molybdenum disulfide is a nanosheet stack: the sheet size is 5-10 nm, the number of stacked layers is <4, and the interlayer spacing is 0.93 nm.

[0017] Preferably, the X-ray diffraction peaks of the nano-molybdenum disulfide include at least four diffraction peaks: 9.5°, 18.2°, 33.2°, and 58.5°.

[0018] The method for preparing the mixture containing ethylene tar and nano-molybdenum disulfide is as follows: heating ethylene tar to a fluid state and mixing it with nano-molybdenum disulfide to obtain a mixture containing ethylene tar and nano-molybdenum disulfide.

[0019] Optionally, the ethylene tar is heated to 40–120°C until it reaches a fluid state.

[0020] Optionally, the volume ratio of the standard state hydrogen gas to the volume of the mixture containing ethylene tar and nano-molybdenum disulfide is 1 to 10:1.

[0021] Preferably, the volume ratio of the standard state hydrogen gas to the volume of the mixture containing ethylene tar and nano-molybdenum disulfide is 4 to 10:1.

[0022] Optionally, the temperature T ranges from 200℃ to 420℃.

[0023] Optionally, the temperature T ranges from 350℃ to 420℃.

[0024] As one specific implementation method, the method for heating ethylene tar described in this application includes the following steps:

[0025] a) Heat ethylene tar to a fluid state and mix it with 50–200 ppm of nano-molybdenum disulfide;

[0026] b) The above liquid mixture of ethylene tar and nano-molybdenum disulfide is kept at the mixing temperature and then mixed with hydrogen gas in a volume ratio of 1 to 10 times.

[0027] c) Heat the ethylene tar to a specified temperature below 420°C as required.

[0028] The method for heating ethylene tar according to the present invention is described in detail below:

[0029] First, heat the ethylene tar to a fluid state. There are no special requirements for the heating temperature, but it should be higher than the freezing point of the ethylene tar to ensure its fluidity; it should not exceed its initial boiling point to avoid component volatilization, and it should not exceed its decomposition temperature. For economic feasibility, a heating temperature of 40–120°C can be chosen. Then, add nano-molybdenum disulfide at a mass ratio of 50–200 ppm to the fluid ethylene tar and mix thoroughly until homogeneous. Mixing methods commonly used in chemical engineering, such as mechanical stirring, static mixers, or mechanical pump circulation, are acceptable and have no special requirements, but attention should be paid to fire prevention, explosion prevention, and other safety requirements, using appropriate compliant equipment and operations. Mixing can be carried out in conventional and safe chemical mixing containers such as reaction tanks or reactors. Conventional chemical analysis methods can be used to sample and analyze the molybdenum content in the ethylene tar to confirm the homogeneity of the ethylene tar and nano-molybdenum disulfide. If the mixing procedure is fixed, the first mixing should use chemical analysis to confirm the homogeneity of the ethylene tar and nano-molybdenum disulfide, and subsequent mixing should use the same mixing time as the first mixing to ensure homogeneity.

[0030] Requirements for nano-molybdenum disulfide. The X-ray diffraction pattern of the mixed nano-molybdenum disulfide is as follows: Figure 1 a. The characteristic diffraction peaks include four peaks at 9.5°, 18.2°, 33.2°, and 58.5°, which are significantly different from the characteristic diffraction peaks of conventional 2H-MoS2. Figure 1 b. Compliant with JCPDS No. 37-1492). Commercial molybdenum sulfide, i.e., 2H-MoS2, is used as raw material, and the material is crushed using conventional mechanical methods such as rolling and ball milling (X-ray diffraction peaks are as follows). Figure 1c) The above-mentioned nano-molybdenum disulfide cannot be prepared. Nano-molybdenum disulfide can be prepared by the method disclosed in Chinese Patent ZL 2016110068033 "A method for preparing a highly active site exposed nano-molybdenum disulfide hydrogenation catalyst", or by the method reported in "Highly Efficient MoS2 Nanocatalysts for Slurry-Phase Hydrogenation of Unconventional Feedstocks into Fuels" (Energy & Fuels 2021, 35(3), 2590-2601). Due to the ultrafine and highly dispersed characteristics of the above-mentioned nano-molybdenum disulfide, and the very small amount of admixture, the mixture of ethylene tar and nano-molybdenum disulfide still maintains the original liquid state of ethylene tar, and its physical properties such as appearance, color, viscosity, density, and freezing point remain unchanged. Even if conventional commercial molybdenum disulfide powder is fully crushed by mechanical crushing methods such as rolling and ball milling, it still maintains a crystal particle size of hundreds of nanometers, and cannot be uniformly dispersed in ethylene tar.

[0031] The liquid mixture of ethylene tar and nano-molybdenum disulfide is maintained at a mixing temperature and then mixed with hydrogen gas at a volume ratio of 1 to 10 times the mixture under standard conditions during transportation. There are no special requirements for the mixing method; appropriate conventional chemical mixing methods can be adopted depending on the specific application scenario, taking into account fire prevention, explosion prevention, and other safety requirements. For example, when the mixture of ethylene tar and nano-molybdenum disulfide is pressurized and transported by pumps such as plunger pumps, gear pumps, centrifugal pumps, or screw pumps, it is mixed online in the pump outlet pipe with hydrogen gas (at standard conditions) at a volume ratio of 1 to 10 times the mixture introduced from another pipe. The gas-liquid mixing effect can be achieved by ensuring a certain length-to-diameter ratio in the pipeline mixing zone or by installing a static mixer in the pipeline. When the mixture of ethylene tar and nano-molybdenum disulfide is placed in a sealed reaction vessel or reactor, the air can be replaced with an inert gas, and then the reaction vessel or reactor can be filled with hydrogen gas (at standard conditions) at a volume ratio of 1 to 10 times the mixture, and gas-liquid mixing can be achieved by mechanical stirring or mechanical pump liquid circulation.

[0032] The aforementioned gas-liquid mixture can be heated to 420℃ without decomposition or coking. There are no special requirements for the heating method; compliant industrial heating equipment can be selected based on the application scenario.

[0033] Using the above heating method, ethylene tar can be heated to a specified temperature below 420°C as needed to meet the heating requirements for further distillation or hydrogenation processes. With this heating method, the amount of nano-molybdenum disulfide added to the ethylene tar is very small and will not affect the physical properties of the ethylene tar feedstock. After further distillation at the specified temperature, the nano-molybdenum disulfide remains only in the heaviest bottom fraction and will not affect the low-boiling-point evaporation components. Similarly, after further hydrogenation or hydrogenation refining at the specified temperature, the low-boiling-point evaporation components can be distilled off, leaving trace amounts of nano-molybdenum disulfide in the bottom residue. Therefore, the nano-molybdenum disulfide added to the ethylene tar will not affect the properties of the light products obtained from further distillation or hydrogenation processes. Of course, if specific requirements are needed, nano-molybdenum disulfide can also be separated from the products obtained from ethylene tar distillation or hydrogenation processes using methods such as packed column adsorption or high-speed centrifugation. In summary, the above heating method for adding trace amounts of nano-molybdenum disulfide to ethylene tar will not significantly affect the properties of the ethylene tar raw material and the processed product, and can meet the needs of most ethylene tar processing.

[0034] Using the heating method described above, the hydrogen gas mixed into the ethylene tar is, under standard conditions, 1 to 10 times the volume of the ethylene tar. The density of ethylene tar is generally approximately 1000 kg / m³. 3 Therefore, the mass of the mixed hydrogen is only about one ten-thousandth to one thousandth of the mass of ethylene tar. The amount of hydrogen mixed is very small and will not affect subsequent distillation separation or hydrogenation reactions.

[0035] Using the heating method described above, the amount of hydrogen mixed into the ethylene tar is only 1 to 10 times the volume of the ethylene tar under standard conditions. In contrast, typical oil refining hydrotreating processes, such as gasoline and diesel hydrorefining, lubricating oil hydrorefining, and wax oil hydrocracking, require a hydrogen-to-feed oil volume ratio of several hundred to several thousand to ensure a significant hydrotreating reaction. Furthermore, the hydrogen consumption in these processes often exceeds one percent of the oil's weight. However, the heating method proposed in this invention uses only about one ten-thousandth to one thousandth of the ethylene tar's weight in hydrogen. Therefore, the heating process does not constitute a hydrotreating or hydrorefining reaction, and it has virtually no impact on the physicochemical properties of the ethylene tar feedstock.

[0036] Studies have found that heavy oil undergoes pyrolysis under high-temperature conditions, with oil decomposition and coke formation occurring simultaneously, both generally considered to follow a free radical reaction mechanism. Direct heating of ethylene tar typically results in pyrolysis above 300°C, producing a small amount of coke, which hinders further processing. Heating to 350°C leads to violent decomposition and complete coking. Using this heating method, the addition of nano-molybdenum disulfide to the ethylene tar exhibits very high catalytic hydrogenation efficiency. Although the mass of the mixed hydrogen is only about one ten-thousandth to one thousandth of the ethylene tar mass, insufficient for significant hydrogenation or hydrogenation refining reactions, trace amounts of hydrogen, under the action of trace catalysts, can rapidly hydrogenate and quench free radicals formed in ethylene tar heated below 420°C, effectively inhibiting free radical-induced cracking and free radical fragment condensation into coke. Experiments have shown that the above heating method is not suitable for heating ethylene tar to above 420°C. The possible reason is that above 420°C, especially reaching 450°C, the rate at which ethylene tar pyrolyzes to generate free radicals is much greater than the rate at which trace amounts of nano-molybdenum disulfide catalyze hydrogen donation, causing ethylene tar to coke.

[0037] The beneficial effects of this application include, but are not limited to:

[0038] By adding 50-200 ppm of nano-molybdenum disulfide to ethylene tar and mixing it with 1-10 times the volume of hydrogen (under standard conditions), ethylene tar can be heated to 420°C without significant decomposition or coking. This meets the heating requirements for further distillation, hydrorefining, or other reactive processing. This heating method, through the addition of trace amounts of nano-molybdenum disulfide and hydrogen, overcomes the limitations of existing ethylene tar heating methods, is highly practical, and its application has positive effects on the comprehensive utilization and deep processing of ethylene tar. Attached Figure Description

[0039] Figure 1 This is a comparison of X-ray diffraction patterns of the nano-MoS2 used in this application and the commercial 2H-MoS2.

[0040] Figure 2 These are simulated distillation curves for three typical ethylene cracked tars. Detailed Implementation

[0041] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0042] Unless otherwise specified, all raw materials and reagents used in this application are commercially purchased and used directly without processing. The instruments and equipment used adopt the manufacturer's recommended scheme and parameters.

[0043] In the embodiments, the crystal structure and interlayer spacing of the samples were characterized using an X'Pert PRO X-ray diffractometer from PANalytical, Netherlands.

[0044] In the examples, the commercial molybdenum disulfide powder was purchased from Sigma-Aldrich 234842 MoS2.

[0045] Three typical ethylene cracking tars were obtained from naphtha steam cracking units in domestic petrochemical enterprises, and their simulated distillation curves are as follows: Figure 2 Ethylene tar A has the heaviest boiling range, being a black solid at room temperature. Its mass percentage is 39.3% in the 180℃-350℃ range, 16.2% in the 350℃-500℃ range, and 44.6% in the >500℃ range. Ethylene tar B is a viscous liquid at room temperature, with a mass percentage of 52.5% in the 180℃-350℃ range, 15.1% in the 350℃-500℃ range, and 32.4% in the >500℃ range. Ethylene tar C has the lightest boiling range, being a flowing liquid at room temperature. Its mass percentage is 4% in the <180℃ range, 62.9% in the 180℃-350℃ range, 14.5% in the 350℃-500℃ range, and 18.6% in the >500℃ range.

[0046] Preparation of nano MoS2 sample A:

[0047] The method disclosed in Chinese Patent ZL 2016110068033, "A method for preparing a highly active site exposed nano-molybdenum disulfide hydrogenation catalyst", was used to prepare nano-molybdenum disulfide, which is denoted as sample A.

[0048] Preparation of nano MoS2 sample B:

[0049] Molybdenum disulfide nanoparticles were prepared using the preparation method reported in "Highly Efficient MoS2 Nanocatalysts for Slurry-Phase Hydrogenation of Unconventional Feedstocks into Fuels" (Energy & Fuels 2021, 35(3), 2590-2601), and were denoted as sample B.

[0050] Preparation of sample C obtained from commercial MoS2:

[0051] Purchased molybdenum disulfide powder was ball-milled in a planetary ball mill for 16 hours to obtain a sample, denoted as sample C.

[0052] Characterization of nano MoS2 samples

[0053] X-ray diffraction analysis was used to characterize samples A, B, commercially available molybdenum disulfide powder, and C. The results showed that the X-ray diffraction patterns of samples A and B were consistent with... Figure 1 In section a), the X-ray diffraction pattern of the commercial molybdenum disulfide powder conforms to... Figure 1 In section b), the X-ray diffraction pattern of sample C conforms to... Figure 1 (c)

[0054] Depend on Figure 1 The X-ray diffraction results showed that the interlayer spacing of sample A was 0.93 nm, which is significantly increased compared to the interlayer spacing of standard MoS2 (0.62 nm).

[0055] Example 1

[0056] Take 1000 kg of ethylene tar A and place it in a 2.5 m... 3 In the raw material tank, the jacket of the tank is heated with steam to heat the ethylene tar to 100°C, liquefying it. Maintaining this temperature, the tank is mechanically stirred at 60 rpm. Then, 0.1 kg of the prepared nano-molybdenum sulfide A is added, and the mixture is stirred for 4 hours. A plunger pump is then used to pump the ethylene tar containing 100 ppm of nano-molybdenum sulfide into a 4 kW tubular furnace at a flow rate of 100 kg / h. The inner diameter of the oil delivery pipe is 20 mm. Hydrogen is injected via the plunger pump outlet bypass at a flow rate of 0.5 m³ (STP) / h, resulting in a hydrogen-to-ethylene tar volume ratio of approximately 5:1. The length of the pipeline from the hydrogen injection port to the tubular furnace inlet is no less than 10 m to ensure good mixing of the ethylene tar with hydrogen before entering the furnace. The ethylene tar remains in the furnace for at least 0.5 hours. The tubular furnace is then turned on, and the outlet temperature of the ethylene tar is controlled at 360°C. The plunger pump ran continuously for more than 4 hours, and samples of ethylene tar heated to 360°C were taken. No decomposition or coking was found.

[0057] Example 2

[0058] 50g of ethylene tar B was placed in a 100ml stainless steel autoclave equipped with a mechanical stirrer. 2.5mg of nano-molybdenum sulfide A was added. The autoclave was sealed, and stirring was started at a speed of 200 rpm. The autoclave was purged with nitrogen three times, followed by hydrogen three times. Then, the autoclave was purged with hydrogen until the gauge pressure reached 0.1MPa. At this point, the ethylene tar contained 50ppm of nano-molybdenum sulfide, and the hydrogen-to-ethylene tar volume ratio was 2:1. The electric heating mantle of the stainless steel autoclave was turned on, and the ethylene tar was heated to 350℃ and maintained for at least 4 hours. The autoclave was then cooled. Upon opening the autoclave, no decomposition or coking was observed in the ethylene tar heated to 350℃.

[0059] Example 3

[0060] 50g of ethylene tar B was placed in a 100ml stainless steel autoclave equipped with a mechanical stirrer, and 10mg of nano-molybdenum sulfide B was added. The autoclave was sealed, and the stirrer was started, with a stirring speed of 300 rpm. The autoclave was purged with nitrogen three times, followed by purging with hydrogen three times. Then, the autoclave was purged with hydrogen until the gauge pressure reached 0.9MPa. At this point, the ethylene tar contained 200ppm of nano-molybdenum sulfide, and the volume ratio of hydrogen to ethylene tar was 10:1. The electric heating mantle of the stainless steel autoclave was turned on, and the ethylene tar was heated to 420℃ and maintained for at least 4 hours. The autoclave was then cooled. Upon opening the autoclave, no decomposition or coking was observed in the ethylene tar heated to 420℃.

[0061] Example 4

[0062] 100g of ethylene tar C was placed in a 200ml stainless steel autoclave equipped with a mechanical stirrer. 8mg of nano-molybdenum sulfide B was added. The autoclave was sealed, and stirring was started at a speed of 100 rpm. The autoclave was purged with nitrogen three times, followed by hydrogen three times. Then, the autoclave was purged with hydrogen until the gauge pressure reached 0.4MPa. At this point, the ethylene tar contained 80ppm of nano-molybdenum sulfide, and the hydrogen-to-ethylene tar volume ratio was 5:1. The electric heating mantle of the stainless steel autoclave was turned on, and the ethylene tar was heated to 380℃ and maintained for at least 4 hours. The autoclave was then cooled. Upon opening the autoclave, no decomposition or coking was observed in the ethylene tar heated to 380℃.

[0063] Comparative Example 1

[0064] 50g of ethylene tar B was placed in a 100ml stainless steel autoclave equipped with a mechanical stirrer. 10mg of molybdenum disulfide C was added, the autoclave was sealed, and the stirrer was started at a speed of 300 rpm. The autoclave was purged with nitrogen three times, followed by hydrogen three times. Then, the autoclave was purged with hydrogen until the gauge pressure reached 0.9MPa. At this point, the ethylene tar contained 200ppm of commercial molybdenum disulfide, and the hydrogen-to-ethylene tar volume ratio was 10:1. The electric heating mantle of the stainless steel autoclave was turned on, and the ethylene tar was heated to 350℃ and maintained for 4 hours. The autoclave was then cooled. Upon opening the autoclave, a gelatinous black solid was observed adhering to the stirrer, indicating that coking occurred in the ethylene tar heated to 350℃. This comparative experiment demonstrates that adding ordinary commercial molybdenum disulfide to heat hydrogen-containing ethylene tar does not prevent coking.

[0065] Comparative Example 2

[0066] 60g of ethylene tar A was placed in a 100ml distillation flask and heated with a heating mantle for simple atmospheric distillation. Distillation products appeared at 210℃. The distillation rate was controlled at 1-2 drops per second, and the temperature was continuously increased. The distillation thermometer showed 335℃, indicating vigorous vaporization of the ethylene tar in the flask. The experiment was immediately stopped, and the heating mantle was removed. After cooling, the flask was observed to contain a large amount of black coking material. This comparative experiment demonstrates that directly heating ethylene tar at around 330-350℃ causes it to decompose and coke.

[0067] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for heating ethylene tar, characterized in that, The mixture containing ethylene tar and nano-molybdenum disulfide is mixed with hydrogen, and then the ethylene tar is heated to temperature T. The temperature T ≤ 420℃.

2. The method according to claim 1, characterized in that, The concentration of the nano-molybdenum disulfide in the mixture containing ethylene tar and nano-molybdenum disulfide is 50–200 ppm.

3. The method according to claim 1, characterized in that, The mixture containing ethylene tar and nano-molybdenum disulfide has a concentration of 50–120 ppm for the nano-molybdenum disulfide.

4. The method according to claim 1, characterized in that, The X-ray diffraction peaks of the nano-molybdenum disulfide include at least four diffraction peaks: 9.5°, 18.2°, 33.2°, and 58.5°.

5. The method according to claim 1, characterized in that, The method for preparing the mixture containing ethylene tar and nano-molybdenum disulfide is as follows: heating ethylene tar to a fluid state and mixing it with nano-molybdenum disulfide to obtain a mixture containing ethylene tar and nano-molybdenum disulfide.

6. The method according to claim 5, characterized in that, Ethylene tar is heated to 40–120°C until it becomes fluid.

7. The method according to claim 1, characterized in that, The volume ratio of the standard state hydrogen gas to the volume of the mixture containing ethylene tar and nano-molybdenum disulfide is 1 to 10:

1.

8. The method according to claim 1, characterized in that, The volume ratio of the standard state hydrogen gas to the volume of the mixture containing ethylene tar and nano-molybdenum disulfide is 4 to 10:

1.

9. The method according to claim 1, characterized in that, The temperature T ranges from 200℃ to 420℃.

10. The method according to claim 1, characterized in that, The temperature T ranges from 350℃ to 420℃.

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