Thin asphalt, pre-thin asphalt

1. Both pre-asphaltene and asphaltene are by-products of the direct coal liquefaction process; their physicochemical properties are characterized by a composition of hydrocarbons with high molecular weights, containing substantial amounts of both aromatic and non-aromatic hydrocarbons. The two are usually distinguished by their boiling point and molecular weight: the former has a lower boiling point and a relatively smaller molecular weight ； Thin asphalt has a higher boiling point and a larger molecular weight. 2. The heavy oils produced by coal liquefaction can indeed be used for asphalt production; they mainly consist of two types of components: pre-asphaltene and asphaltene. The technology for producing asphalt is typically a physical separation method, in which components suitable for making asphalt are separated from heavy oils through steps such as fractionation and distillation. 3. The hydrogenation conversion principle of pre-asphaltene and asphaltene essentially involves using hydrogenation reactions to transform these heavier, more complex hydrocarbon molecular structures into lighter, simpler ones, thereby producing light oils. During this process, the carbon chains of the macromolecules are broken, and hydrogen atoms are added, which lowers the boiling point of the product and results in lighter oil products that are easier to handle and use. .

1. First question: The pre-asphaltene and asphaltene produced in the coal liquefaction process are both substances separated from the products of direct coal liquefaction. They possess some similar physicochemical properties, but there are also some differences between them. The following is a detailed explanation of their physical and chemical properties as well as the methods for distinguishing them: Physical and Chemical Properties – Appearance and Form: Both pre-asphaltene and asphaltene are viscous, but their specific form may vary depending on the type of coal, the liquefaction conditions, and the subsequent processing methods. Solubility: Both have a certain degree of solubility, but their solubility levels differ. Asphaltite is slightly soluble in benzene, but insoluble in n-hexane or cyclohexane ； The solubility characteristics of the former pitch dilute solutions may vary depending on the specific preparation conditions and separation methods, but they generally exhibit similar differences in solubility. Molecular weight: The average molecular weight of pre-asphaltenes is approximately 500, while the molecular weight of proto-asphaltenes may vary depending on the conditions during their preparation; however, it generally falls within a similar range. Density and viscosity: Both pre-asphaltene-rich and asphaltene-rich materials have high density and viscosity, but the specific values can vary depending on factors such as the type of coal and the liquefaction conditions. Stability: Both are relatively stable at room temperature, but prolonged exposure to air may cause changes in their properties due to oxidation and other factors. Distinguishing method: Solubility test: Differentiation is achieved by utilizing the difference in their solubility in solvents. As mentioned earlier, asphaltene is slightly soluble in benzene but insoluble in n-hexane or cyclohexane ； The solubility of the former asphaltene may need to be determined based on specific preparation conditions and separation methods in order to understand its solubility characteristics. Therefore, the two can be initially distinguished through solubility tests. Molecular weight determination: Differentiation is achieved by measuring the molecular weights of the two. Although their molecular weights may fall within a similar range, their specific molecular weight distributions can differ. Therefore, the two can be further distinguished using molecular weight determination methods such as gel permeation chromatography (GPC). Other chemical property tests: The two can also be distinguished based on their differences in other chemical properties, such as chemical analysis methods like infrared spectroscopy and nuclear magnetic resonance. These methods can provide more detailed structural information, which helps to further distinguish between pre-asphaltenes and asphaltenes.

2. The second question: Generally speaking, heavy oil is a product of the coal liquefaction process, and its composition and properties are related to the type of raw coal used, the liquefaction conditions, as well as the subsequent treatment processes. Regarding the technology for producing asphalt, the process of converting heavy oil into asphalt involves a combination of physical separation and chemical reactions. The following is a detailed explanation of this process: Physical separation of heavy oil – First, the heavy oil is separated from the coal liquefaction products. This step is typically carried out through processes such as distillation and cracking to separate heavy oils from other components (such as light oils and gases). Preparation of base materials for asphalt: After obtaining heavy oil, it is necessary to further separate it into products with different boiling point ranges through physical methods (such as distillation and extraction), in order to obtain the base materials for asphalt. Chemical reactions: The role of chemical reactions: Although physical separation plays an important role in the asphalt production process, chemical reactions are also essential. For example, in the process of converting heavy oil into asphalt, chemical reactions such as hydrogenation, cracking, and polymerization may occur to improve the properties and quality of the asphalt. Refining and blending: Impurities are removed through the refining process to improve quality, ensuring that asphalt products meet relevant standards. Finally, adjustments are made in accordance with market demands to modify the performance parameters of asphalt, so as to meet the requirements of various applications. In summary, the heavy oil produced by coal liquefaction can be used to manufacture asphalt, a process that involves the combined use of physical separation and chemical reactions. To determine whether this heavy oil belongs to the category of former asphaltenes or asphaltenic components, it is necessary to analyze its chemical composition and properties in detail. At the same time, the technology for producing asphalt also needs to be selected and optimized based on the specific requirements of the raw materials and the final product.

Third question: The hydrogenation conversion of pre-asphaltene and asphaltene is one of the important reactions in the coal liquefaction process. The following is an overview of the principles behind the hydrodesulfurization of asphaltene and the hydrogenation conversion of asphaltene: I. Principles of hydrogenation conversion: Stepwise hydrogenation reaction: Stepwise hydrogenation conversion primarily occurs during the isothermal stage and is a type of radical reaction. During this process, chemical bonds are weakened and broken primarily due to the combined effects of active hydrogen, solvents, catalysts, etc., and then combine with hydrogen radicals. The reaction rate is related not only to the distribution of bond dissociation energies of the unconverted coal, but also to the concentration of unconverted coal, the concentration of active hydrogen, the type of catalyst, and its concentration. Intermediate products: Arenes and proto-arenes are intermediate products of the sequential reactions that occur after coal pyrolysis. In the early stage of coal liquefaction reactions, relatively high-molecular-weight proto-arenes and arenes appear due to pyrolytic bond breaking. As progressive hydrogenation proceeds, the relatively strong bridge bonds in coal macromolecules are further broken, leading to an increase in pre-arenes and arenes. Subsequently, the former arenes continue to be hydrogenated to form more arenes, while the arenes are also hydrogenated to produce oils and gases with lower molecular weights. Sources of active hydrogen: There are mainly two sources of active hydrogen. One is the release of hydrogen radicals from hydrogenated aromatics in the solvent, which converts the dissolved hydrogen gas into hydrogen radicals through the solvent ； Another source is dissolved hydrogen, which becomes active hydrogen under the action of a catalyst. II. Hydrogenation conversion process
Heating-up stage: Primarily involves the rapid pyrolytic conversion of hydrogenatable components. At this stage, hydrogen consumption is very low, so the hydrogen partial pressure has little effect on the reaction. The reaction kinetic model of hydrodeoxygenation components in fast pyrolysis can be described by a pseudo-first-order kinetic model. Constant temperature stage: The gradual hydrogenation conversion mainly occurs during this stage. Unconverted coal is mostly high-degree-condensed macromolecular compounds, making it difficult to re-form proto-arenes and arenes. Therefore, both protoarenes and arenes exhibit a maximum yield as the hydrogenation reaction proceeds; the maximum for protoarenes occurs earlier, while that for arenes occurs later. Cooling stage: Reactions still occur at higher temperatures, and their kinetic equations can be derived based on specific conditions. III. Hydrogenation conversion products: Main products: The main products resulting from hydrogenation conversion include oil, gas, as well as unconverted aromatics and protoaromatics. Product properties: The product after hydrogenation has a lower molecular weight and higher stability, meeting the **standards for petroleum products.

Thank you both. Judging from the IP address, those two people are likely designers in coal-to-oil conversion. Question: To what extent has the technology for direct coal-to-oil conversion progressed currently? Apart from Shenhua’s 108 direct liquefaction plant and the Yanchang 50 co-processing plant, which other plants have been built and put into operation? In which regions have direct liquefaction projects been approved for development and construction?

Upgrading Demonstration Project for Direct Coal Liquefaction, Ordos Coal-to-Oil Branch of China Shenhua Coal-to-Oil Chemical Co., Ltd. Location of construction: Wulamulun Town, Yijinhuoluo Banner, Ordos City. Plant capacity: A new direct coal liquefaction production line with an annual capacity of 2.16 million tons is planned to be built. Technical features: It relies on a new generation of technologies for direct coal liquefaction with fully independent intellectual property rights. Construction progress: Construction is scheduled to begin at the end of 2024, with production set to start by the end of 2027. **Energy Group’s Hami Energy Integration and Innovation Base project: Location of construction – Chahaiquan Industrial Park, Hami City, Xinjiang. Scale of the facilities: Once the entire production chain of this project is in operation, the coal direct liquefaction production capacity will reach 3.2 million tons per year. Technical features: It utilizes the second-generation coal direct liquefaction technology owned by the Energy Group and covered by independent intellectual property rights. Construction progress: The project officially commenced at the end of March 2024, and is expected to be completed and put into operation by the end of 2027. **Energy Group’s Project for the Engineering Development of Second-Generation Coal Direct Liquefaction Technology. Location: Ordos City, Inner Mongolia (Coal-to-Oil Company). Technical features: This project aims to increase the processing capacity of the coal slurry used as raw material, extend the operational cycle of the facility, improve energy efficiency, and enhance the overall effectiveness of the preliminary projects related to coal direct liquefaction. Construction progress: The project officially commenced on November 29, 2024, marking another significant step forward for China in the field of direct coal liquefaction technology.