A preparation method and application of a complementary refining catalyst for coal tar hydrocracking to naphthenic base oil

Abstract

The present application relates to coal tar high value utilization and catalyst manufacturing technical field, solve the existing coal tar hydrogenation make up finishing catalyst exists noble metal load higher, active component uneven dispersion and the problem of insufficient deep hydrogenation dearomatic performance, provide a kind of for coal tar hydrogenation preparation method and application of supplementary finishing catalyst for naphthenic base oil, the method includes: macroporous alumina, mordenite, amorphous silica-alumina and auxiliary extruding agent are blended extrusion, dry and calcine and obtain clover shape composite carrier;Platinum precursor is mixed with dispersant and is prepared into homogeneous impregnation solution, and impregnation is carried out on the composite carrier under vacuum condition;The catalyst precursor obtained after impregnation is carried out dry, calcination and hydrogen reduction, and the reduced catalyst finished product is obtained.The present application can effectively improve the atomic utilization rate of platinum component, and utilize the synergistic effect between it and composite carrier, reduce the amount of noble metal while realizing the deep conversion of aromatic hydrocarbon.

Description

Technical Field

[0001] This invention relates to the field of high-value utilization of coal tar and catalyst manufacturing technology, and in particular to a method for preparing and applying a supplementary refining catalyst for the hydrogenation of coal tar to cycloalkyl oil. Background Technology

[0002] Coal tar is a byproduct of coal pyrolysis. It has a complex composition, typically containing polycyclic aromatic hydrocarbons, phenols, and sulfur- and nitrogen-containing heteroatom compounds. Through pretreatment, hydrorefining, hydroisomerization, and supplementary refining processes, coal tar can be converted into naphthenic specialty oils with excellent low-temperature performance, solubility, and insulation properties. Supplementary refining primarily removes residual aromatic hydrocarbons and other unstable components from the oil to improve its color, oxidation stability, and thermal stability.

[0003] Existing catalysts for supplemental refining of coal tar hydrogenation typically use alumina, silica-alumina materials, or molecular sieves as supports, and load active metal components such as nickel, molybdenum, tungsten, platinum, or palladium. Non-precious metal catalysts exhibit relatively low hydrogenation activity, usually requiring high temperatures and pressures to achieve deep dearomatization, resulting in high energy consumption and a tendency to initiate cracking side reactions. While precious metal catalysts offer higher hydrogenation activity, ensuring effective dispersion of the active components on the support and achieving deep dearomatization often necessitates increasing the precious metal loading or constructing a platinum-palladium bimetallic system, leading to increased catalyst costs. Furthermore, when using conventional impregnation methods, the active components tend to accumulate locally on the support surface, limiting the number and accessibility of precious metal active sites and hindering their full hydrogenation potential.

[0004] Chinese patent CN114749194A discloses a coal tar hydrogenation catalyst and its preparation method. This catalyst uses a silicon-aluminum material as a support, loading Group VIB and / or Group VIII metal active components. The active metals used specifically include at least one of Mo, W, Ni, and Co. In its preparation process, an active metal precursor solution and a carbon precursor solution are mixed to form an active metal-containing solution. The active metal is then loaded onto the support via impregnation, followed by drying and calcination to obtain the coal tar hydrogenation catalyst. This patent, through the introduction of carbon precursors and corresponding calcination treatment, inhibits the aggregation of active metals, improves the utilization rate of active metals and the hydrogenation performance of the catalyst, and simultaneously improves the catalyst's water resistance, impurity removal ability, and cracking performance by combining specific silicon-aluminum materials. It is mainly suitable for the coal tar hydrogenation treatment stage. However, for naphthenic oils that have undergone pre-hydrorefining and hydroisomerization treatment, the supplementary refining stage focuses more on the deep removal of residual aromatics and unstable components, placing higher demands on the catalyst's hydrogenation activity and the effective utilization of active components. Especially when using precious metal active components, the amount of precious metal and its distribution on the support directly determine the number of effective active sites, thus affecting the catalyst's supplemental purification effect. Therefore, it is still necessary to further optimize the loading and utilization performance of the catalyst's active components.

[0005] Therefore, how to improve the dispersion of active components on the support and enhance the deep hydrogenation and dearomatization performance of the catalyst while reducing the amount of precious metals used is an urgent technical problem to be solved. Summary of the Invention

[0006] In view of this, the present invention provides a method for preparing a supplementary refining catalyst for the hydrogenation of coal tar to produce cycloalkyl oil and its application, in order to solve the problems of existing supplementary refining catalysts for the hydrogenation of coal tar having high noble metal loading, uneven dispersion of active components and insufficient deep hydrogenation and dearomatization performance.

[0007] In a first aspect, the present invention provides a method for preparing a supplementary refining catalyst for the hydrogenation of coal tar to cycloalkyl oil, the method comprising: Macroporous alumina, mordenite, amorphous silica-alumina and extrusion aid are co-extruded to obtain a clover-shaped carrier. The clover-shaped carrier is dried and calcined to obtain a composite carrier; A homogeneous impregnation solution was prepared by mixing the platinum precursor and a pre-defined dispersant. Under vacuum conditions, the homogeneous impregnation solution is impregnated onto the composite carrier; The catalyst precursor obtained after impregnation is dried, calcined, and reduced with hydrogen to obtain the reduced catalyst product.

[0008] Preferably, the mass percentage of macroporous alumina, mordenite and amorphous silica is (40-70):(10-30):(10-30).

[0009] Preferably, the extrusion aid comprises one or more of guar gum powder, starch, and methylcellulose, and the extrusion aid accounts for 1.0 to 5.0% of the total mass of macroporous alumina, mordenite, and amorphous silica-alumina.

[0010] Preferably, the drying and calcination of the clover-shaped carrier to obtain the composite carrier comprises: The clover-shaped carrier was dried at 80–120°C for 4–12 hours to obtain the dried carrier. The dried carrier is calcined at 500–650°C for 2–6 hours to obtain the composite carrier.

[0011] Preferably, the platinum precursor includes one or more of chloroplatinic acid, chloroplatinic acid, platinum nitrate, platinum acetylacetonate, and platinum acetate.

[0012] Preferably, the dispersant includes one or more of citric acid, tartaric acid, trichloroacetic acid, and ethylenediaminetetraacetic acid, and the dispersant accounts for 0.5 to 3.0% of the total mass of the composite carrier.

[0013] Preferably, the pressure under the vacuum condition is -0.06MPa to -0.01MPa.

[0014] Preferably, the process of drying, calcining, and reducing the impregnated catalyst precursor to obtain the reduced catalyst product includes: The catalyst precursor obtained after impregnation was dried at 80–120°C for 4–12 h to obtain the dried catalyst precursor. The dried catalyst precursor was calcined at 450–550°C in air for 2–6 hours to obtain the calcined catalyst precursor. The calcined catalyst precursor is reduced for 2-4 hours at 350-500℃ under a hydrogen atmosphere to obtain the reduced catalyst product, wherein the hydrogen flow rate is 100-300 mL / min.

[0015] Preferably, the loading of platinum in the catalyst accounts for 0.1 to 0.6% of the total mass of the catalyst.

[0016] In a second aspect, the present invention provides the application of a catalyst prepared by a supplementary refining catalyst for the hydrogenation of coal tar to cycloalkyl oils as described in the first aspect in the production of cycloalkyl oils.

[0017] In summary, the beneficial effects of the present invention are as follows: This invention provides a method for preparing a supplementary refining catalyst for the hydrogenation of coal tar to cycloalkyl oil and its application. The method involves co-extruding macroporous alumina, mordenite, amorphous silica-alumina, and an extrusion aid, followed by drying and calcination to construct a clover-shaped composite support with high pore volume, suitable acidic sites, and a stable structure. Macroporous alumina has a high specific surface area and abundant pore structure, which is beneficial for reactant diffusion and active component loading. Amorphous silica-alumina is used to adjust the acidity and texture properties of the composite support. Mordenite utilizes its twelve-membered ring main pore structure and some acidic sites to preferentially adsorb aromatic molecules from the raw materials, activating relatively stable aromatics that are difficult to directly hydrogenate. Simultaneously, the bridging hydroxyl groups on the surface of mordenite can receive active hydrogen species overflowing from adjacent metal surfaces and react with the aromatic molecules adsorbed thereon, thus synergistically promoting the deep hydrogenation saturation of residual aromatics.

[0018] Furthermore, by utilizing the stabilizing and dispersing effects of dispersants on the platinum precursor, agglomeration and localized enrichment of the platinum precursor on the surface of the composite support can be reduced. During vacuum impregnation, after removing the gas from the pores of the composite support through negative pressure, the platinum precursor can achieve high dispersion within the support, significantly increasing the number of effective active sites. Under the synergistic effect of the high-pore-volume composite support with suitable acidic sites and the uniformly dispersed active components, aromatic molecules can be effectively adsorbed and undergo efficient hydrogenation saturation. At the same time, while inhibiting platinum agglomeration and improving platinum atom utilization, the amount of noble metal loading required to achieve the target hydrogenation performance is reduced. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, and these are all within the protection scope of the present invention.

[0020] Figure 1 This is a schematic diagram of the overall process for preparing a supplementary refining catalyst for the hydrogenation of coal tar to cycloalkyl oil in Example 1 of the present invention; Figure 2 This is a schematic diagram of the process in Example 1 of the present invention, which involves drying, calcining and reducing the impregnated catalyst precursor with hydrogen to obtain the reduced catalyst product. Detailed Implementation

[0021] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present invention and are not configured to limit the present invention. For those skilled in the art, the present invention can be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the invention.

[0022] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0023] It should be noted that all actions involving the acquisition of signals, information, or data in this invention are carried out in compliance with the relevant data protection laws and regulations of the locality and with authorization from the owner of the relevant device.

[0024] Example 1 Please see Figure 1 This invention provides a method for preparing a supplementary refining catalyst for the hydrogenation of coal tar to cycloalkyl oil, the method comprising: Macroporous alumina, mordenite, amorphous silica-alumina and extrusion aid are co-extruded to obtain a clover-shaped carrier. Specifically, macroporous alumina is used to provide high pore volume, specific surface area, and mechanical strength, which is beneficial for diffusion mass transfer and loading of active components; mordenite, with its regular twelve-membered ring channels and suitable acidic sites, is used to adsorb and activate aromatic molecules, promoting their hydrogenation saturation; amorphous silica-alumina is used to adjust the acidity and texture properties of the composite support. In preparation, macroporous alumina, mordenite, and amorphous silica-alumina are weighed according to a predetermined mass ratio, and one or more of guar gum powder, starch, or methylcellulose are added as extrusion aids. After uniform mixing, an appropriate amount of diluted nitric acid aqueous solution is added and kneaded to form a plastic wet material. The kneaded wet material is fed into an extruder, extruded through a clover-shaped perforated plate, and cut to obtain a clover-shaped support. The clover-shaped structure can increase the catalyst's external surface area and bed porosity while ensuring the mechanical strength of the support, which is beneficial for improving mass transfer efficiency and maintaining long-term industrial operation.

[0025] The clover-shaped carrier is dried and calcined to obtain a composite carrier; Specifically, the extruded clover-shaped carrier is dried at 80℃~120℃ for 4 to 12 hours to remove moisture from the carrier; then the dried clover-shaped carrier is calcined at 500℃~650℃ for 2 to 6 hours to decompose the extrusion aid, binder, etc., and the sintering and bonding between the components are used to form a structurally stable composite carrier, while controlling its surface acidity and pore distribution.

[0026] A homogeneous impregnation solution was prepared by mixing the platinum precursor and a pre-defined dispersant. Specifically, the platinum precursor can be one or more of chloroplatinic acid, chloroplatinous acid, platinum nitrate, platinum acetylacetonate, or platinum acetate; the dispersant can be one or more of citric acid, tartaric acid, trichloroacetic acid, or ethylenediaminetetraacetic acid, used to stabilize the platinum precursor in the impregnation solution and improve its dispersion. During preparation, the platinum precursor is dissolved in deionized water according to the predetermined platinum loading, and a dispersant is added at 0.5% to 3.0% of the composite carrier mass. The mixture is then thoroughly mixed to obtain a homogeneous impregnation solution without obvious stratification or precipitation.

[0027] Under vacuum conditions, the homogeneous impregnation solution is impregnated onto the composite carrier; Specifically, the composite carrier is placed in a vacuum impregnation device and evacuated to a gauge pressure of -0.06MPa to -0.01MPa to remove residual gas in the carrier pores; then the homogeneous impregnation solution is drawn into the impregnation device and impregnated into the pores of the composite carrier using an equal-volume impregnation method.

[0028] The catalyst precursor obtained after impregnation is dried, calcined, and reduced with hydrogen to obtain the reduced catalyst product.

[0029] Specifically, the impregnated catalyst precursor is dried at 80℃~120℃ for 4 hours~12 hours to obtain a dried catalyst precursor; the dried catalyst precursor is calcined at 450℃~550℃ in air atmosphere for 2 hours~6 hours to remove anionic ligands and dispersants, and to convert the platinum precursor into a reducible oxidized platinum species, to obtain a calcined catalyst precursor; subsequently, the calcined catalyst precursor is reduced at 350℃~500℃ in hydrogen atmosphere for 2 hours~4 hours, with the hydrogen flow rate controlled at 100mL / min~300mL / min, to convert the oxidized platinum species into a zero-valent platinum active component with hydrogenation activity, to obtain the reduced catalyst product.

[0030] Preferably, the mass percentage of macroporous alumina, mordenite and amorphous silica is (40-70):(10-30):(10-30).

[0031] Specifically, macroporous alumina, mordenite, and amorphous silica-alumina are weighed in a mass ratio of (40–70):(10–30):(10–30) and mixed until the dry powders are uniformly mixed. By adjusting the relative content of the three carrier components, the resulting composite carrier has suitable pore structure, mechanical strength, and acidity distribution, which is conducive to the diffusion of aromatic molecules and the loading of active components.

[0032] Preferably, the extrusion aid comprises one or more of guar gum powder, starch, and methylcellulose, and the extrusion aid accounts for 1.0 to 5.0% of the total mass of macroporous alumina, mordenite, and amorphous silica-alumina.

[0033] Specifically, the extrusion aid improves the extrusion performance of the wet material through lubrication and plasticization, enhancing its molding ability and indirectly regulating the pore structure and mechanical strength of the carrier. During preparation, one or more of the following are weighed at 1.0%–5.0% of the total mass of macroporous alumina, mordenite, and amorphous silica-alumina: guar gum powder, starch, and methylcellulose. These are mixed evenly with the dry carrier powder, and a suitable amount of diluted nitric acid solution is added for kneading to obtain a wet material with suitable plasticity and binding properties, facilitating continuous extrusion molding. The extrusion aid can be decomposed and removed during subsequent calcination, helping to form secondary pores in the composite carrier, improving its pore connectivity and mass transfer of reactants within the carrier.

[0034] Preferably, the drying and calcination of the clover-shaped carrier to obtain the composite carrier comprises: The clover-shaped carrier was dried at 80–120°C for 4–12 hours to obtain the dried carrier. The dried carrier is calcined at 500–650°C for 2–6 hours to obtain the composite carrier.

[0035] Specifically, the extruded clover-shaped carrier is dried at 80℃~120℃ for 4 hours~12 hours to remove moisture, resulting in a dried carrier. Subsequently, the dried carrier is calcined at 500℃~650℃ for 2 hours~6 hours to decompose extrusion aids such as guar gum powder, starch or methylcellulose and binder nitric acid, forming certain pores in the carrier to improve pore connectivity. At the same time, a stable composite structure is formed through the sintering effect between macroporous alumina, mordenite zeolite and amorphous silica-alumina, providing a carrier basis for the subsequent loading of active components.

[0036] Preferably, the platinum precursor includes one or more of chloroplatinic acid, chloroplatinic acid, platinum nitrate, platinum acetylacetonate, and platinum acetate.

[0037] Specifically, the platinum precursor is a platinum-containing compound that can be converted into a zero-valent platinum active component through calcination and hydrogen reduction. One or more of chloroplatinic acid, chloroplatinic acid, platinum nitrate, platinum acetylacetonate, and platinum acetate can be selected. When preparing the impregnation solution, the amount of the platinum precursor added is determined according to the predetermined platinum loading, and it is dissolved in deionized water or a suitable solvent and mixed with a dispersant to form a homogeneous platinum-containing impregnation solution. After impregnation, the platinum precursor is dispersed on the surface and inside the pores of the composite support, and can be converted into a zero-valent platinum active component with hydrogenation activity through subsequent calcination and hydrogen reduction.

[0038] Preferably, the dispersant includes one or more of citric acid, tartaric acid, trichloroacetic acid, and ethylenediaminetetraacetic acid, and the dispersant accounts for 0.5 to 3.0% of the total mass of the composite carrier.

[0039] Specifically, the dispersant is used to stabilize the platinum precursor in the impregnation solution and improve its dispersion. During preparation, one or more of citric acid, tartaric acid, trichloroacetic acid, and ethylenediaminetetraacetic acid are weighed at 0.5% to 3.0% of the total mass of the composite carrier and added to the impregnation solution containing the platinum precursor, then mixed thoroughly. The dispersant can reduce the aggregation of the platinum precursor in the impregnation solution and its localized enrichment on the surface of the composite carrier.

[0040] Preferably, the pressure under the vacuum condition is -0.06MPa to -0.01MPa.

[0041] Specifically, the pressure is relative to the external atmospheric pressure. During impregnation, the composite carrier is placed in a sealed vacuum impregnation device, and a vacuum is drawn until the gauge pressure is maintained at -0.06 MPa to -0.01 MPa to expel residual gas in the carrier pores; then, a homogeneous impregnation solution is drawn in, allowing it to enter the interior of the composite carrier pores under pressure difference and capillary action. Utilizing the negative pressure environment, the permeation resistance caused by liquid surface tension can be overcome, achieving high dispersion and controllable loading of the platinum precursor.

[0042] Preferably, please refer to Figure 2 The process of drying, calcining, and reducing the impregnated catalyst precursor to obtain the reduced catalyst product includes: The catalyst precursor obtained after impregnation was dried at 80–120°C for 4–12 h to obtain the dried catalyst precursor. The dried catalyst precursor was calcined at 450–550°C in air for 2–6 hours to obtain the calcined catalyst precursor. The calcined catalyst precursor is reduced for 2-4 hours at 350-500℃ under a hydrogen atmosphere to obtain the reduced catalyst product, wherein the hydrogen flow rate is 100-300 mL / min.

[0043] Specifically, the impregnated catalyst precursor is dried at 80℃~120℃ for 4 to 12 hours, allowing the solvent to gradually evaporate and platinum-containing species to deposit within the pores and on the surface of the composite support. During drying, the heating rate and layer thickness should be controlled to prevent excessive solvent evaporation, which could cause platinum species to migrate to the outer layer of the particles, thus maintaining a uniform distribution formed by vacuum impregnation. After drying, the dried catalyst precursor is calcined at 450℃~550℃ in air for 2 to 6 hours to remove dispersants and other components, converting the platinum precursor into oxidized platinum species. The oxidized platinum species can also form a stronger interaction with the support, inhibiting severe sintering during subsequent high-temperature reduction. The calcined catalyst precursor is placed in the constant temperature zone of a reaction tube or activation furnace and reduced at 350℃~500℃ in a hydrogen atmosphere for 2 to 4 hours. The hydrogen flow rate is controlled at 100mL / min~300mL / min to allow the flowing hydrogen to continuously pass through the catalyst bed, reducing the high-valence oxide platinum species to zero-valence platinum active components with high hydrogenation activity. At the same time, the water vapor generated during the reduction process is carried away, breaking the thermodynamic equilibrium limit and inhibiting the sintering of noble metal particles. Specific Implementation Example 1 Step 1: Catalyst support forming In a kneading apparatus, 214.3 g of macroporous alumina, 52.6 g of mordenite zeolite, and 68.5 g of amorphous aluminosilicate powder were weighed out, and 5.0 g of guar gum powder was added as an extrusion aid. The mixture was then thoroughly mixed. 11.5 g of nitric acid was diluted with 168.0 g of deionized water and added to the above-mentioned dry powder mixture. Kneading continued until a wet material with suitable plasticity and binding properties was formed. The thoroughly kneaded wet material was transferred to an extruder and extruded through a clover-shaped perforated plate to obtain a clover-shaped carrier.

[0045] Step 2: Drying and calcining the catalyst support The obtained clover-shaped carrier was placed in a drying oven and dried at 110℃ for 4 hours to remove internal moisture. After drying, the shaped carrier was transferred to a muffle furnace and calcined at 550℃ for 4 hours to allow the organic components such as guar gum powder to decompose thermally and form a structurally stable composite carrier. After cooling, the supplementary refined catalyst carrier was obtained.

[0046] Step 3: Impregnation of active components Add 21.61 mL of a pre-prepared 0.05 g / mL chloroplatinic acid solution to 48.5 g of deionized water, then add 1.0 g of citric acid as a dispersant. Shake and mix until the liquid is clear to obtain a homogeneous impregnation solution containing the platinum precursor. Weigh 100 g of the supplemented refined catalyst support and place it in a glass vacuum impregnation apparatus. Connect the vacuum pump, impregnation device, and impregnation liquid bottle in sequence. After evacuating to a preset vacuum level, draw the homogeneous impregnation solution into the glass vacuum impregnation apparatus, allowing it to uniformly impregnate the support pores under vacuum conditions to obtain the impregnated catalyst precursor.

[0047] Step 4: Catalyst drying and calcination The impregnated catalyst precursor was dried at 110℃ for 4 hours to remove residual moisture from its surface and pores. Then, the dried catalyst precursor was transferred to a muffle furnace for calcination: first, the temperature was raised to 200℃ and held for 4 hours, then raised to 500℃ and held for 4 hours, allowing the chloroplatinic acid precursor and the dispersant citric acid to decompose, and the oxidized platinum species to be stably loaded onto the support. After calcination, the oxidized supplementary refined catalyst was obtained.

[0048] Step 5: Reduction of the finished catalyst The obtained oxidized supplementary refining catalyst was loaded into the isothermal section of the reaction tube of a vertical activation furnace. Flowing hydrogen gas was introduced, and the temperature was raised to 480°C under a hydrogen atmosphere. The catalyst was then reduced at this temperature for 3 hours, converting the supported oxidized platinum species into zero-valent platinum active components with hydrogenation activity. After reduction, the catalyst was cooled and removed under a nitrogen protective atmosphere to prevent the metallic platinum from oxidizing upon contact with air. The removed catalyst was sieved to obtain the finished supplementary refining catalyst for the hydrogenation of coal tar to naphthenic oils.

[0049] Table 1 Physicochemical properties of the dedicated supplemental refining catalyst The properties of the finished catalyst are shown in Table 1, which illustrates the main physicochemical properties of the prepared supplementary refining catalyst. Among them, the specific surface area is 276 m². 2The catalyst exhibits a high specific surface area and abundant pore structure, which is beneficial for the dispersion and loading of active components and the diffusion and mass transfer of reactant molecules. Its lateral compressive strength is 200.3 N / cm, demonstrating good mechanical strength and preventing breakage or pulverization during loading, transportation, and high-pressure hydrogenation reactions. The bulk density is 0.607 g / mL, allowing for suitable catalyst loading within a given reactor volume. The catalyst has a clover-shaped morphology with a length of 3–8 mm and a cross-sectional diameter of 1.6–2.2 mm, effectively increasing the catalyst's external surface area and bed porosity, improving reactant mass transfer efficiency, and balancing bed pressure drop and long-term operational stability. These results indicate that the obtained catalyst possesses excellent comprehensive performance in terms of texture, mechanical strength, and particle morphology, meeting the requirements for active component dispersion, reactant mass transfer, and industrial loading in the supplementary refining process of coal tar hydrogenation to naphthenic oil.

[0050] Table 2 Hydrodearomatization performance of catalysts at different reaction temperatures The catalyst evaluation used feedstock from a naphthenic oil production unit under a specific operating condition, with an aromatic content of 33.0%. During the evaluation process, the reaction pressure was controlled at 15.0 MPa and the volumetric hourly space velocity (VHSV) at 0.5 h⁻¹. -1 The hydrogen-to-oil ratio was set to 600, and the effect of the reaction temperature on the catalyst's hydrodearomatization performance was investigated. Here, volume hourly space velocity (VHSV) is the volume of feedstock oil passing through a unit volume of catalyst bed per unit time; a lower VHSV value indicates a longer contact time between the feedstock oil and the catalyst. The hydrogen-to-oil ratio is the volume ratio of hydrogen to feedstock oil, used to characterize the hydrogen supply capacity of the reaction system. Table 2 shows that at 180℃, the aromatic content in the reaction products decreased from 33.0% of the feedstock oil to 0.0121%, indicating that the catalyst has significant aromatic hydrogenation saturation capacity even at lower reaction temperatures. As the reaction temperature increased sequentially from 180℃ to 200℃, 220℃, 240℃, and 260℃, the aromatic content in the products further decreased to 0.0067%, 0.0044%, 0.0023%, and 0.0019%, respectively, indicating that appropriately increasing the reaction temperature within this temperature range is beneficial for further reducing the residual aromatic content. The above results indicate that the catalyst can achieve deep removal of residual aromatics from coal tar hydrogenation products within the investigated temperature range, and exhibits high hydrogenation activity at a lower reaction temperature, demonstrating a good synergistic effect between the composite support and the single metal platinum active component.

[0051] Example 2 This invention provides an application of a catalyst prepared by the above-described method for supplementary refining catalysts for the hydrogenation of coal tar to cycloalkyl oils in the production of cycloalkyl oils.

[0052] In summary, the present invention provides a method for preparing and applying a supplementary refining catalyst for the hydrogenation of coal tar to cycloalkyl oil. This involves co-extruding macroporous alumina, mordenite, amorphous silica-alumina, and an extrusion aid, followed by drying and calcination, to construct a clover-shaped composite support with high pore volume, suitable acidic sites, and a stable structure. Macroporous alumina possesses a high specific surface area and abundant pore structure, which is beneficial for reactant diffusion and active component loading. Mordenite utilizes its pore structure and acidic sites to adsorb and activate aromatic molecules. Amorphous silica-alumina is used to adjust the acidity and texture properties of the composite support. The clover-shaped structure helps increase the catalyst's external surface area and bed porosity, improving mass transfer efficiency. Furthermore, the dispersant's stabilizing and dispersing effect on the platinum precursor reduces its agglomeration and local enrichment on the composite support surface. During vacuum impregnation, after removing the gas from the pores of the composite support under negative pressure, the platinum precursor can achieve high dispersion within the support, significantly increasing the number of effective active sites. After impregnation, the catalyst precursor is dried and calcined to convert the platinum precursor into a reducible oxidized platinum species, which is then reduced with hydrogen to form a zero-valent platinum active component with hydrogenation activity. Under the synergistic effect of a composite support with high pore volume and suitable acidic sites and a uniformly dispersed active component, aromatic molecules can be effectively adsorbed and undergo efficient hydrogenation saturation. At the same time, while inhibiting platinum agglomeration and improving platinum atom utilization, the amount of noble metal loading required to achieve the target hydrogenation performance is reduced.

[0053] It should be clarified that the present invention is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present invention is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of the present invention.

[0054] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0055] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0056] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0057] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0058] It should also be noted that the exemplary embodiments mentioned in this invention describe methods or systems based on a series of steps or apparatus. However, this invention is not limited to the order of the steps described above; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0059] The above description is merely a specific embodiment of the present invention. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the protection scope of the present invention.

Claims

1. A method for preparing a supplementary refining catalyst for the hydrogenation of coal tar to cycloalkyl oil, characterized in that, The method includes: Macroporous alumina, mordenite, amorphous silica-alumina and extrusion aid are co-extruded to obtain a clover-shaped carrier. The clover-shaped carrier is dried and calcined to obtain a composite carrier; A homogeneous impregnation solution was prepared by mixing the platinum precursor and a pre-defined dispersant. Under vacuum conditions, the homogeneous impregnation solution is impregnated onto the composite carrier; The catalyst precursor obtained after impregnation is dried, calcined, and reduced with hydrogen to obtain the reduced catalyst product.

2. The method for preparing a supplementary refining catalyst for the hydrogenation of coal tar to cycloalkyl oil according to claim 1, characterized in that, The mass percentage of macroporous alumina, mordenite and amorphous silica is (40-70): (10-30): (10-30).

3. The method for preparing a supplementary refining catalyst for the hydrogenation of coal tar to cycloalkyl oil according to claim 1, characterized in that, The extrusion aid includes one or more of guar gum powder, starch, and methylcellulose, and the extrusion aid accounts for 1.0 to 5.0% of the total mass of macroporous alumina, mordenite, and amorphous silica-alumina.

4. The method for preparing a supplementary refining catalyst for the hydrogenation of coal tar to cycloalkyl oil according to claim 1, characterized in that, The clover-shaped carrier is dried and calcined to obtain a composite carrier comprising: The clover-shaped carrier was dried at 80–120°C for 4–12 hours to obtain the dried carrier. The dried carrier is calcined at 500–650°C for 2–6 hours to obtain the composite carrier.

5. The method for preparing a supplementary refining catalyst for the hydrogenation of coal tar to cycloalkyl oil according to claim 1, characterized in that, The platinum precursor includes one or more of chloroplatinic acid, chloroplatinic acid, platinum nitrate, platinum acetylacetonate, and platinum acetate.

6. The method for preparing a supplementary refining catalyst for the hydrogenation of coal tar to cycloalkyl oil according to claim 1, characterized in that, The dispersant includes one or more of citric acid, tartaric acid, trichloroacetic acid, and ethylenediaminetetraacetic acid, and the dispersant accounts for 0.5 to 3.0% of the total mass of the composite carrier.

7. The method for preparing a supplementary refining catalyst for the hydrogenation of coal tar to cycloalkyl oil according to claim 1, characterized in that, The pressure under the vacuum conditions is -0.06MPa to -0.01MPa.

8. The method for preparing a supplementary refining catalyst for the hydrogenation of coal tar to cycloalkyl oil according to claim 1, characterized in that, The process of drying, calcining, and reducing the impregnated catalyst precursor with hydrogen to obtain the reduced catalyst product includes: The catalyst precursor obtained after impregnation was dried at 80–120°C for 4–12 h to obtain the dried catalyst precursor. The dried catalyst precursor was calcined at 450–550°C in air for 2–6 hours to obtain the calcined catalyst precursor. The calcined catalyst precursor is reduced for 2-4 hours at 350-500℃ under a hydrogen atmosphere to obtain the reduced catalyst product, wherein the hydrogen flow rate is 100-300 mL / min.

9. The method for preparing a supplementary refining catalyst for the hydrogenation of coal tar to cycloalkyl oil according to claim 1, characterized in that, The loading of platinum in the catalyst accounts for 0.1 to 0.6% of the total mass of the catalyst.

10. The application of a catalyst prepared by any one of the supplementary refining catalysts for the hydrogenation of coal tar to naphthenic oils as described in any one of claims 1-9 in the production of naphthenic oils.

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