A catalyst for the regeneration of waste mineral oil, its preparation method and application

Abstract

This application provides a catalyst for the regeneration of waste mineral oil, its preparation method, and its application, belonging to the field of catalysts. The method includes: mixing a molybdenum source, isooctanoic acid, cobalt isooctanoate, organic acid anhydride, a sulfur-containing compound, and hexadecyltrimethylammonium bromide, followed by a preliminary complexation reaction at 50–110°C for 0.5–2 h to obtain a first reaction system; raising the temperature of the first reaction system to 110–160°C, then adding aminopropyltriethoxysilane to the first reaction system, and reacting at 110–160°C for 1–3 h to obtain a second reaction system; further raising the temperature of the second reaction system to 160–230°C, and performing a sulfurization reaction at 160–230°C for 2–4 h. Through the molecular and nanostructure design of the catalyst, the core contradictions of easy coking and difficult conversion of asphaltenes in the slurry-bed hydrogenation regeneration of waste mineral oil are simultaneously and efficiently resolved.

Description

Technical Field

[0001] This application relates to the field of catalyst technology, and in particular to a catalyst for the regeneration of waste mineral oil, its preparation method, and its application. Background Technology

[0002] With the continuous growth in demand for lubricating oil in the industrial sector, the amount of waste mineral oil (especially waste lubricating oil) is increasing year by year. This type of waste mineral oil contains only a small amount of deteriorated substances, with the majority being reusable effective components. Improper handling or indiscriminate disposal will not only cause a serious waste of petroleum, a non-renewable resource, but also cause significant environmental pollution to soil, water, and air due to oil seepage and volatilization.

[0003] Currently, the industry mainly adopts vacuum distillation + solvent extraction and vacuum distillation + fixed-bed hydrorefining technologies for waste mineral oil regeneration. However, these traditional technologies generally suffer from common pain points that are difficult to overcome. In the vacuum distillation stage, heavy components such as gums and asphaltenes in waste mineral oil are prone to condensation reactions due to local overheating, forming coke. These coke adhere to the inner wall of the distillation unit and the surface of subsequent processing equipment, causing blockages, reduced heat transfer efficiency, and forcing frequent shutdowns for cleaning, making long-term continuous operation impossible. In the solvent extraction or fixed-bed hydrorefining process, on the one hand, solvent extraction has limited selectivity for separating gums and asphaltenes, easily causing the loss of effective components with impurities, resulting in a low final product yield. On the other hand, the catalysts used in fixed-bed hydrorefining are mostly supported, and coke in waste mineral oil easily deposits in the pores of the catalyst support, causing blockage of active sites, rapidly reducing catalytic activity, and further exacerbating the problems of poor unit operation stability and high maintenance costs. Ultimately, this leads to poor economic efficiency of the entire regeneration process, making it difficult to meet the needs of large-scale industrial applications. To address the shortcomings of traditional technologies, the industry has increasingly focused on the application potential of slurry-bed hydrogenation technology in waste mineral oil regeneration. Slurry-bed hydrogenation, with its characteristics of uniform mixing, high mass transfer efficiency, and gradual temperature distribution, can reduce the risk of coking caused by localized overheating to a certain extent, and is considered an effective direction for overcoming existing technological bottlenecks. However, the core performance of slurry-bed hydrogenation is highly dependent on the catalyst used. Existing catalysts suitable for slurry beds either lack sufficient hydrogenation activity to efficiently break down the complex molecular structures of gums and asphaltenes, failing to convert them into effective components; or they have weak anti-coking capabilities, still experiencing problems such as active phase agglomeration and coke adsorption and deposition during the reaction, leading to rapid catalytic performance degradation. These catalysts have consistently failed to simultaneously resolve the two core contradictions of "difficult conversion of gums and asphaltenes" and "prone coking of the reaction system," hindering the full realization of the advantages of slurry-bed hydrogenation technology in waste mineral oil regeneration. Therefore, there is an urgent need to develop a catalyst that, through precise molecular and nanostructure design, can simultaneously achieve high hydrogenation activity and strong anti-coking performance to promote the technological upgrade of waste mineral oil regeneration processes. Summary of the Invention

[0004] This application provides a catalyst for the regeneration of waste mineral oil, its preparation method, and its application, in order to solve the following technical problem: how to simultaneously and efficiently resolve the core contradiction of easy coking and difficult conversion of asphaltenes in the reaction system during the slurry bed hydrogenation regeneration of waste mineral oil through the molecular and nanostructure design of the catalyst.

[0005] In a first aspect, this application provides a method for preparing a catalyst for the regeneration of waste mineral oil, the method comprising the following steps:

[0006] S1. Molybdenum source, isooctanoic acid, cobalt isooctanoate, organic acid anhydride, sulfur-containing compound and hexadecyltrimethylammonium bromide are mixed and then subjected to a preliminary complexation reaction at 50-110℃ for 0.5-2h to obtain a first reaction system containing micelle assemblies.

[0007] S2. Raise the temperature of the first reaction system to 110-160°C, then add aminopropyltriethoxysilane to the first reaction system and react at 110-160°C for 1-3 hours, so that the aminopropyltriethoxysilane can be coordinated and hydrolyzed on the micelle assembly simultaneously to obtain a second reaction system containing an intermediate.

[0008] S3. The temperature of the second reaction system is further increased to 160-230°C, and the sulfidation reaction is carried out at 160-230°C for 2-4 hours, so that the intermediate is converted in situ into a catalyst with a Co-Mo-S active phase and a silicon-oxygen network structure.

[0009] Optionally, the catalyst, by weight, is composed of the following chemical raw materials: molybdenum source: 6-10 parts, isooctanoic acid: 20-30 parts, cobalt isooctanoate: 1-2 parts, organic acid anhydride: 8-12 parts, sulfur-containing compound: 0.5-2 parts, hexadecyltrimethylammonium bromide: 0.3-0.8 parts, and aminopropyltriethoxysilane: 0.5-1.5 parts.

[0010] Optionally, the molybdenum source includes at least one of ammonium heptamolybdate, ammonium molybdate, molybdic acid, and molybdenum trioxide.

[0011] Optionally, the organic anhydride includes at least one of acetic anhydride and propionic anhydride.

[0012] Optionally, the sulfur-containing compound includes at least one of elemental sulfur, dimethyl disulfide, and thioacetamide.

[0013] In a second aspect, this application provides a catalyst for the regeneration of waste mineral oil prepared by the method described in any one of the first aspects, wherein the catalyst contains 10-30% molybdenum and 1-5% cobalt by mass fraction.

[0014] Optionally, the active component of the catalyst product is a core-shell nanocomposite material.

[0015] The core layer is a Co-Mo-S hydrogenated active phase, and the shell layer is an organic-inorganic hybrid layer composed of isooctanoic acid derivatives and a silicon-oxygen network.

[0016] Optionally, the Co-Mo-S hydrogenation active phase exists in the form of nanosheets, and the nanosheets have a sheet length of 5-15 nm and a stacking number of 2-4 layers.

[0017] Thirdly, this application provides an application of the catalyst for waste mineral oil regeneration as described in any of the second aspects, wherein the catalyst is used in a slurry-bed hydrogenation process for waste mineral oil, and the mass of the catalyst added is 0.05 to 0.3% of the mass of the waste mineral oil.

[0018] Optionally, the slurry-bed hydrogenation process includes the following parameters: reaction temperature of 320–400℃, hydrogen partial pressure of 5.0–16.0 MPa, reaction time of 1–3 h, and hydrogen-to-oil ratio of (600–1500):1.

[0019] The technical solutions provided in this application have the following advantages compared with the prior art:

[0020] This application provides a method for preparing a catalyst for waste mineral oil regeneration. Through precise molecular design and nanostructure construction, it systematically solves the core contradiction between coking and conversion rate in the slurry-bed hydrogenation process of waste mineral oil. Its technological essence is embodied in the synergistic design at three levels:

[0021] First, at the molecular functional level, a bifunctional active center for cracking and hydrogenation was constructed by introducing cobalt isooctanoate and aminopropyltriethoxysilane (APS). The simultaneous coordination and hydrolytic condensation of APS on the micelle assembly forms a molecular-level silicon-oxygen network of acidic sites around the metal center (providing cracking functionality), while the Co-Mo-S active phase formed with cobalt (generated by sulfidation in step S3) provides excellent hydrogenation activity. This design allows the asphaltenes macromolecules to be adsorbed by the acidic sites first, resulting in weak C / C bond cleavage. The generated free radical fragments are then captured and hydrogenated by the adjacent Co-Mo-S center, achieving a continuous reaction pathway of "cracking first, then saturation," mechanistically cutting off the channel for free radical polycondensation to form coke.

[0022] Secondly, at the nanostructure level, the micelle assemblies guided by hexadecyltrimethylammonium bromide (CTAB) serve as templates, ensuring high dispersion of the active phase precursor. After vulcanization and curing in step S3, the final product is a core-shell nanocomposite material: the core layer is a highly hydrogenated Co-Mo-S nanosheet, and the shell layer is an organic-inorganic hybrid layer composed of isooctanoic acid derivatives and a silicon-oxygen network. This hybrid shell effectively prevents the sintering and aggregation of Co-Mo-S nanosheets through steric hindrance, locking in its high specific surface area and high activity. Simultaneously, the organic portion composed of isooctanoic acid derivatives endows the catalyst with excellent oil solubility, allowing it to be highly dispersed in the oil phase like a "smart missile" and precisely anchored on the surface of the asphaltene micelles, greatly eliminating mass transfer resistance and improving reaction efficiency.

[0023] Ultimately, at the macroscopic performance level, the synergistic effect of the aforementioned molecules and nanostructures enables the catalyst to simultaneously and efficiently achieve deep conversion of asphaltenes and suppress coking during slurry-bed hydrogenation regeneration. The unique core-shell and nanosheet structure ensures the catalyst's structural stability and anti-aging ability, while the in-situ sulfidation (S3 step) during preparation ensures the perfection and efficiency of the active phase structure, enabling it to utilize the sulfur in the feedstock oil for self-sulfidation and stable operation in subsequent applications.

[0024] Therefore, this design fundamentally unifies the usually contradictory characteristics of high activity and high stability, achieving a synergistic improvement in both long-term operation of the device and the yield of high-value products. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 A schematic flowchart illustrating a method for preparing a catalyst for the regeneration of waste mineral oil, provided in an embodiment of this application;

[0028] Figure 2 This is a SEM image of the active component of the catalyst product provided in Example 1 of this application;

[0029] Figure 3 This is a TEM image of the active component of the catalyst product provided in Example 1 of this application. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0032] Figure 1 This is a schematic flowchart illustrating a method for preparing a catalyst for the regeneration of waste mineral oil, as provided in an embodiment of this application.

[0033] like Figure 1 As shown, this application provides a method for preparing a catalyst for the regeneration of waste mineral oil, the method comprising the following steps:

[0034] S1. Molybdenum source, isooctanoic acid, cobalt isooctanoate, organic acid anhydride, sulfur-containing compound and hexadecyltrimethylammonium bromide are mixed and then subjected to a preliminary complexation reaction at 50-110℃ for 0.5-2h to obtain a first reaction system containing micelle assemblies.

[0035] S2. Raise the temperature of the first reaction system to 110-160°C, then add aminopropyltriethoxysilane to the first reaction system and react at 110-160°C for 1-3 hours, so that the aminopropyltriethoxysilane can be coordinated and hydrolyzed on the micelle assembly simultaneously to obtain a second reaction system containing an intermediate.

[0036] S3. The temperature of the second reaction system is further increased to 160-230°C, and the sulfidation reaction is carried out at 160-230°C for 2-4 hours, so that the intermediate is converted in situ into a catalyst with a Co-Mo-S active phase and a silicon-oxygen network structure.

[0037] The preparation method of the waste mineral oil regeneration catalyst provided in this application adopts a three-step progressive process. By precisely controlling the intermolecular interactions, the catalyst's microstructure and catalytic performance are directionally constructed. The technical logic and mechanism of each step are as follows:

[0038] Step S1 is the initial complexation and self-assembly stage, with "constructing reaction templates and pre-organized active centers" as its core. After mixing raw materials such as molybdenum source, isooctanoic acid, and cobalt isooctanoate, the mixture reacts at 50–110°C. The surfactant hexadecyltrimethylammonium bromide (CTAB) self-assembles into micelles within the system. These micelles act as "nanoreactors," providing confined space for subsequent reactions. Simultaneously, the carboxyl groups of isooctanoic acid undergo complexation reactions with metal ions from the molybdenum and cobalt sources, generating oil-soluble metal-organic acid precursors. These precursors are loaded or adsorbed onto the hydrophilic-hydrophobic interface of the micelles through interfacial interactions, ultimately forming highly organized "pre-assembled structures." This lays the foundation for the subsequent formation of uniformly sized nanostructures and avoids the disordered aggregation of metal precursors.

[0039] Step S2 is the stage for introducing and functionalizing acidic sites, and it is crucial for constructing the catalyst's "bifunctional interface." After raising the system temperature to 110–160 °C, aminopropyltriethoxysilane (APS) is added. APS acts as a "smart connecting unit": on one hand, its amino group (-NH2) can coordinate with the Mo or Co center in the metal-organic acid precursor formed in S1, achieving molecular-level anchoring and ensuring a tight bond between the active component and the subsequently formed structural units; on the other hand, its ethoxy group (-OC2H5) hydrolyzes at this temperature to generate silanol groups (-Si-OH), which further undergo dehydration condensation to gradually form an inorganic silicon-oxygen (Si-O-Si) network. This process occurs simultaneously at the micellar template interface, introducing molecular-level L-acidic sites (unsaturated silicon) and B-acidic sites (silanol groups) to the catalyst, and constructing the prototype of the "shell" in the core-shell structure, achieving the synergistic integration of hydrogenation active sites and acidic sites.

[0040] Step S3 is the sulfidation and structural solidification stage, and it is the final step in the catalyst's "activation" and "structural stabilization." As the temperature continues to rise to 160–230°C, the sulfur-containing compounds decompose and release H2S or active sulfur species. These sulfur species undergo redox reactions with Mo and Co in the metal precursor, generating a Co-Mo-S active phase with a nano-thin layer structure in situ. This is the core source of activity for the catalyst's hydrogenation performance. Simultaneously, the silicon-oxygen network precursor formed in S2 undergoes complete cross-linking and solidification at high temperature, forming a robust silicon-oxygen network shell. This shell physically prevents the internal Co-Mo-S nanosheets from contacting each other, effectively preventing sintering and aggregation at high temperatures. This locks in the highly active nanostructure, ensuring the catalyst's stability and long-term effectiveness in waste mineral oil regeneration reactions.

[0041] This application ensures the formation of a uniform and efficient nano-thin structure in the catalyst's active phase (Co-Mo-S) through in-situ pre-sulfurization during the preparation stage (S3), enabling it to be in a highly active state upon entering the slurry bed reactor. This not only eliminates the risks of coking and deactivation caused by incomplete initial sulfidation in the reactor, a common problem with traditional catalysts, but also allows the catalyst to achieve self-sulfidation using sulfur from waste mineral oil and operate stably for extended periods. This eliminates the cumbersome and time-consuming external pre-sulfurization process in traditional methods, simplifying the process and reducing operating costs.

[0042] In some embodiments, the catalyst, by weight, is composed of the following chemical raw materials: molybdenum source: 6-10 parts, isooctanoic acid: 20-30 parts, cobalt isooctanoate: 1-2 parts, organic acid anhydride: 8-12 parts, sulfur-containing compound: 0.5-2 parts, hexadecyltrimethylammonium bromide: 0.3-0.8 parts, and aminopropyltriethoxysilane: 0.5-1.5 parts.

[0043] In some embodiments, the molybdenum source includes at least one of ammonium heptamolybdate, ammonium molybdate, molybdic acid, and molybdenum trioxide.

[0044] In some embodiments, the organic anhydride includes at least one of acetic anhydride and propionic anhydride.

[0045] In some embodiments, the sulfur-containing compound includes at least one of elemental sulfur, dimethyl disulfide, and thioacetamide.

[0046] The functions of each raw material in the waste mineral oil regeneration catalyst provided in this application are as follows:

[0047] Molybdenum source (ammonium heptamolybdate, ammonium molybdate, etc.): As an "active phase framework provider," the molybdenum source provides Mo atoms to the catalyst. In the subsequent sulfidation process, Mo atoms are transformed into the core of MoS2 nanosheets, forming the basic framework of the hydrogenation reaction; at the same time, the edge sites of MoS2 nanosheets are the main active sites of the hydrogenation reaction, directly determining the hydrogenation capacity of the catalyst, and their content and dispersion depend on the initial complexation efficiency of the molybdenum source.

[0048] Isooctanoic acid (OCA) functions as both a primary coordinating agent and an oil-soluble guarantor. Its carboxyl group (-COOH) forms stable coordination bonds with molybdenum and cobalt ions, generating oil-soluble metal carboxylate complexes, ensuring uniform dispersion of the metal precursor in the organic system. Its branched alkyl structure, through steric hindrance, prevents premature aggregation of the metal complex, while simultaneously imparting excellent oil compatibility to the final catalyst. This is crucial for the dispersion and reaction of the catalyst in waste mineral oil (oily systems). Furthermore, the complexation reaction between isooctanoic acid and the metal source relies on the dehydration effect of the organic acid anhydride, resulting in a synergistic effect.

[0049] Cobalt isooctanoate acts as both a "synergist" and an "electronic regulator." The Co ions it provides, after sulfidation, preferentially occupy the edge sites of MoS2 nanosheets, forming a Co-Mo-S active phase together with Mo and S. From an electronic structure perspective, Co doping alters the electron cloud density of the S atoms at the MoS2 edge, significantly reducing the H2 dissociation barrier and thus greatly enhancing the catalyst's hydrogenation activity. Compared to a single MoS2 active phase, the introduction of Co can increase hydrogenation efficiency several times over.

[0050] Organic acid anhydrides (acetic anhydride, propionic anhydride, etc.): mainly act as "dehydrating agents" and "reaction drivers". In the S1 complexation reaction, the complexation of metal ions with isooctanoic acid is accompanied by the generation of trace amounts of water. Organic acid anhydrides can undergo hydrolysis with this water, removing water from the system and shifting the equilibrium of the complexation reaction towards the formation of metal-organic acid precursors. This strongly drives the complexation reaction to proceed completely and avoids uneven dispersion of precursors due to residual water.

[0051] Hexadecyltrimethylammonium bromide (CTAB): It serves as both a "structure-directing agent" and a "nanotemplate." As a cationic surfactant, its molecules self-assemble in organic systems to form micelles via a process where the hydrophilic end (quaternary ammonium salt group) faces inward and the hydrophobic end (long-chain alkyl group) faces outward. The size and morphology of the micelles directly determine the nanostructure size of the subsequent catalyst. At the same time, the hydrophilic interior of the micelles provides a suitable microenvironment for the complexation of metal precursors, ensuring that the metal components can be uniformly distributed at the nanoscale, which is key to forming small-sized, highly dispersed catalysts.

[0052] Aminopropyltriethoxysilane (APS): It serves a dual function as both an "acidic site source" and a "structural stabilizer." In addition to the "coordination-hydrolysis condensation" effect mentioned earlier, the silicon-oxygen network it forms not only supports acidic sites but also works synergistically with the CTAB micelle template to construct the outer shell of the core-shell structure. At the same time, the coordination between the amino groups and the metal centers of APS enhances the binding force between the active phase (Co-Mo-S) and the silicon-oxygen network, preventing the active phase from detaching during the reaction and improving the structural stability of the catalyst.

[0053] Sulfur-containing compounds (elemental sulfur, dimethyl disulfide, etc.) act as "sulfiding agents" and "active phase builders." Under the high-temperature conditions of S3, sulfur-containing compounds decompose to produce active sulfur species. These sulfur species can reduce and sulfide the Mo (high valence state) and Co (high valence state) in the metal precursor, transforming them into a sulfide state (Co-Mo-S) with high hydrogenation activity. The decomposition rate and sulfur release directly affect the formation efficiency of the Co-Mo-S active phase. If the sulfur release is insufficient, the active phase will not form completely. If the release is too fast, it may cause local sulfur excess, generating inactive sulfide impurities.

[0054] Based on a general inventive concept, this application provides a catalyst for the regeneration of waste mineral oil prepared by the method described in any one of the above, wherein the catalyst contains 10-30% molybdenum and 1-5% cobalt by mass fraction.

[0055] The catalyst in this application macroscopically presents as a homogeneous and stable oily liquid, essentially a colloidal dispersion system in which nanoscale core-shell structured active particles are highly dispersed in an organic continuous phase. From a microscopic perspective, the continuous phase of the system consists of a mixed oil phase composed of unreacted isooctanoic acid, reaction products of organic acid anhydrides (such as isooctyl acetate), hexadecyltrimethylammonium bromide (CTAB) and its derivatives, which can provide a good oil-soluble environment for subsequent catalytic reactions. The dispersed phase is a large number of uniformly sized core-shell structured nanocomposite materials, in which the core part is a Co-Mo-S hydrogenation active phase, which exists in the form of 2-4 stacked nanosheets with a sheet length of 5-15 nm, and the outer shell part is an organic-inorganic hybrid layer, with the core and shell tightly bound together by intermolecular forces. Because nanoparticles possess size effects (Brownian motion can counteract the effects of gravity) and hybrid shells can generate steric hindrance effects, these nanoparticles can be stably dispersed in the oil phase for a long time, ultimately exhibiting a uniform, non-layered oily liquid on a macroscopic scale, enabling them to exert efficient catalytic effects directly in reaction systems such as slurry beds.

[0056] The molybdenum (10–30%) and cobalt (1–5%) content in the catalyst are set based on a comprehensive optimization of the number of active sites, synergistic effects, and structural stability. For molybdenum, as the framework element of the Co-Mo-S active phase, its content directly determines the number of hydrogenation active sites: if the molybdenum content is below 10%, the formation of Co-Mo-S nanosheets will be insufficient, resulting in a lack of hydrogenation active sites and failing to meet the hydrogenation requirements of polycyclic aromatic hydrocarbons and heteroatom compounds in waste mineral oil; if the molybdenum content is above 30%, excessive Mo can easily cause the number of nanosheet stacked layers to exceed 4 layers or the sheet length to exceed 15 nm. This not only reduces the exposed edge active sites (hydrogenation mainly occurs at the edges of nanosheets), but may also lead to agglomeration due to the close proximity of nanoparticles overcoming shell barriers, thereby reducing catalytic efficiency. Therefore, a molybdenum content of 10–30% ensures the formation of an appropriate amount of uniformly dispersed Co-Mo-S nanosheets (5–15 nm sheet length, 2–4 layers stacked), achieving a balance between the number and dispersion of active sites. Cobalt, acting as an "electron promoter" in the Co-Mo-S active phase, requires a suitable ratio with molybdenum. If the cobalt content is below 1%, it cannot effectively occupy the edge sites of the MoS2 nanosheets, making it difficult to enhance the hydrogen dissociation ability of S atoms through electronic regulation, resulting in a weak synergistic promoting effect. If the cobalt content is above 5%, excess Co will detach from the Co-Mo-S phase to form an independent Co9S8 inert phase. This inert phase has low hydrogenation activity and may adsorb onto the surface of active sites, causing blockage and wasting cobalt resources. A cobalt content of 1–5% ensures that Co atoms are embedded to the MoS2 edge to the maximum extent, forming a highly active Co-Mo-S phase, significantly improving the hydrogenation reaction rate and selectivity.

[0057] In some embodiments, the active component of the catalyst product is a core-shell nanocomposite material.

[0058] The core layer is a Co-Mo-S hydrogenated active phase, and the shell layer is an organic-inorganic hybrid layer composed of isooctanoic acid derivatives and a silicon-oxygen network.

[0059] In some embodiments, the Co-Mo-S hydrogenation active phase exists in the form of nanosheets, and the nanosheets have a sheet length of 5 to 15 nm and a stacking number of 2 to 4 layers.

[0060] The formation of the core-shell structure of the catalyst is the result of the synergistic effect of "template guidance-step assembly-in-situ solidification" in the preparation process. The specific formation path is as follows: In the initial complexation and self-assembly step of S1, CTAB, as a surfactant, will self-assemble to form a micelle template. Its hydrophilic core can provide enrichment sites for metal ions. Meanwhile, the metal-organic acid complex generated by the reaction of isooctanoic acid with molybdenum source and cobalt isooctanoate will be adsorbed on the hydrophilic-hydrophobic interface of the micelle, thereby realizing the nanoscale pre-dispersion and positioning of Mo and Co ions, laying the spatial foundation for the subsequent formation of the core layer. After entering the S2 acidic site introduction and functionalization step, the added aminopropyltriethoxysilane (APS) will undergo a coordination reaction with the metal complex at the micelle interface through its own amino group, achieving molecular-level anchoring. At the same time, the ethoxy group of APS hydrolyzes and condenses at a temperature of 110-160℃ to form a rudimentary silicon-oxygen network. The isooctanoic acid and its derivatives (such as esters generated by the reaction with organic acid anhydrides) that do not participate in the complexation will be adsorbed on the outside of the silicon-oxygen network due to hydrophobicity, together forming the precursor of the organic-inorganic hybrid shell. At this point, the preliminary structure of the core (metal complex)-shell (hybrid precursor) has been basically formed. In the S3 vulcanization and structural solidification step, under a high-temperature environment of 160–230°C, sulfur-containing compounds decompose to produce active sulfur. This active sulfur reacts with Mo and Co ions within the micelles, generating Co-Mo-S nanosheets (i.e., the core layer) in situ. Simultaneously, the silicon-oxygen network in the shell precursor undergoes complete cross-linking and solidification at high temperature. Isooctanoic acid derivatives (metal isooctanoate complexes and isooctanoate esters, etc.) are stably bound to the outside of the silicon-oxygen network through hydrophobic interactions, ultimately forming a complete core-shell structure in which the "Co-Mo-S core is tightly wrapped by an organic-inorganic hybrid layer." In this structure, the hybrid shell not only prevents the aggregation of Co-Mo-S nanosheets through spatial barrier effects, but its organic portion also enhances the compatibility of the core-shell particles with the oil phase medium, further ensuring the dispersion stability of the core-shell particles in the oil phase.

[0061] Based on a general inventive concept, this application provides an application of the catalyst for waste mineral oil regeneration as described in any one of the above claims, wherein the catalyst is used in a slurry-bed hydrogenation process for waste mineral oil, and the mass of the catalyst added is 0.05 to 0.3% of the mass of the waste mineral oil.

[0062] In some embodiments, the slurry-bed hydrogenation process includes the following parameters: reaction temperature of 320–400°C, hydrogen partial pressure of 5.0–16.0 MPa, reaction time of 1–3 h, and hydrogen-to-oil ratio of (600–1500):1.

[0063] The catalyst prepared in this application is highly adaptable to the slurry-bed hydrogenation process of waste mineral oil because its structural characteristics and performance advantages are highly compatible with the requirements of the slurry-bed process, and it can specifically solve the pain points of the existing process. This can be analyzed from the following aspects:

[0064] From the perspective of basic process adaptation, the core requirement of slurry bed hydrogenation is that the catalyst can be uniformly dispersed in the oil phase to form a stable "slurry" system to ensure mass transfer efficiency. The catalyst in this application happens to possess this key characteristic. The catalyst itself is an oily liquid in which nano-sized core-shell structured active particles are dispersed in the organic phase. It has excellent compatibility with waste mineral oil (oily system), and the added mass is only 0.05-0.3% of the waste mineral oil. This dosage avoids the formation of multi-layered aggregates after sulfidation due to excessive dosage, and also ensures that the particles are fully mixed with the oil phase in the slurry bed through Brownian motion. There are no local reaction dead zones caused by the uneven dispersion of traditional particulate catalysts, which perfectly matches the process requirement of "solid-liquid homogeneous contact" in slurry beds.

[0065] In terms of its ability to address the pain points of existing processes, this catalyst precisely tackles the core challenges of "easy coking and short continuous operation" in the hydrogenation of waste mineral oil. On the one hand, the asphaltenes in waste mineral oil are prone to cracking at around 300℃, generating free radical fragments. If these free radicals are not stabilized in time, they will condense and form coke. This catalyst can efficiently promote the combination of hydrogen molecules with these free radicals, directionally generating diesel or base oil components, thus inhibiting coke formation from the source of the reaction. On the other hand, the catalyst does not have the porous structure of traditional supports. Its active component (nanoscale Co-Mo-S thin layer) will not clog the pores due to metal or coke deposition. Traditional supported catalysts often experience a rapid decline in activity due to pore blockage, requiring frequent shutdowns for replacement. However, this catalyst is minimally affected by coking, and the active component does not age, supporting long-term continuous operation of the process and solving the pain point of "short continuous operation time" in existing processes.

[0066] From the perspective of adaptability to hydrogenation efficiency and resource recovery, the high activity of this catalyst synergistically complements the reaction conditions of the slurry bed process, achieving efficient recovery of ideal components from waste mineral oil. The catalyst contains 10–30 wt% molybdenum, providing ample active sites for the Co-Mo-S hydrogenation active phase. Furthermore, the nanoscale active phase flakes have a large specific surface area and no diffusion or mass transfer obstacles. Under the process parameters of slurry bed (reaction temperature 320–400℃, hydrogen partial pressure 5.0–16.0 MPa), H2 can rapidly dissolve and contact the catalyst's active sites, efficiently cracking and hydrogenating ineffective components such as asphaltenes and gums into effective components such as diesel and lubricating oil base oils. This not only improves resource recovery but also reduces gas yield by inhibiting excessive free radical cracking, avoiding the problem of insufficient recovery of effective components in traditional processes. In addition, the catalyst can maintain stable performance within a reaction time range of 1–3 h and a hydrogen-to-oil ratio of (600–1500):1, further verifying its compatibility with the slurry bed hydrogenation process. The catalyst's comprehensive advantages in dispersibility, anti-coking properties, hydrogenation activity, and process compatibility make it an ideal choice for slurry bed hydrogenation processes of waste mineral oil.

[0067] In summary, this application has formed a multi-dimensional and in-depth advantage system in the technical design and practical application of waste mineral oil regeneration catalysts. From the source design of the preparation process to the practical value of industrial application, it has achieved optimization and breakthrough of existing technologies.

[0068] At the preparation process level, its core advantage lies in "step-by-step precise control and molecular-level synergy," rather than a simple superposition of steps. In the three-step progressive process, each step plays a clear and interconnected role: the first step constructs a micellar template through surfactant self-assembly, while simultaneously completing the complexation and pre-positioning of the metal precursor, laying the foundation for the "nanoreactor" for subsequent structure formation and avoiding the uneven activity caused by the random distribution of metal ions in traditional preparation; the second step introduces a silane reagent that not only anchors the metal center through coordination but also simultaneously completes hydrolysis and condensation to construct the shell precursor, achieving a molecular-level combination of "active sites and functional layers," rather than a simple subsequent coating; the third step, high-temperature sulfidation, simultaneously achieves the generation of the active phase and the solidification of the shell, ensuring the integrity and stability of the core-shell structure. The entire process, from molecular assembly to structural shaping, forms a closed loop, ensuring the controllability and consistency of catalyst performance.

[0069] In terms of structural design, this application innovatively adopts a "core-shell nanocomposite material," the advantage of which lies in the deep adaptation between structure and performance. The hydrogenation active phase of the core layer exists in a specific sheet-like morphology. This morphology not only maximizes the exposure of the edge active sites required for the reaction but also reduces the mutual shielding of active sites, thereby improving the reaction efficiency per unit mass of catalyst. The organic-inorganic hybrid structure of the shell layer has a dual function: the inorganic part provides rigid support, effectively preventing the sintering and agglomeration of the active phase nanosheets during high-temperature reactions, thus avoiding the loss of active sites; the organic part is highly compatible with the oily system of waste mineral oil, ensuring that the catalyst particles can be stably dispersed in the oil phase without settling or agglomerating due to insufficient compatibility. This balanced design of "rigid stability + flexible dispersion" is difficult to achieve with traditional single-structure catalysts.

[0070] In terms of performance, the catalyst exhibits a triple advantage of "high activity, high stability, and high adaptability." From an activity perspective, the nanoscale structure and abundant sites of its active phase, combined with the regulatory effect of cobalt on the electronic structure, enable highly efficient catalysis of difficult-to-treat asphaltenes and other ineffective components in waste mineral oil, achieving a breakthrough from "difficult conversion" to "directional conversion." Furthermore, there is no diffusion or mass transfer obstruction during the reaction, significantly improving the contact efficiency between H2 and the active sites, further enhancing the hydrogenation effect. From a stability perspective, the porous structure without a traditional support fundamentally solves the "pore blockage" problem. Traditional supported catalysts often experience a sharp drop in activity due to pore blockage caused by coke or metal deposition, while… The catalyst in this application effectively avoids this pain point through shell protection and a non-porous design. At the same time, it can actively inhibit free radical condensation and coking, reduce the coverage of active sites by coke, and significantly extend the catalyst's service life and continuous process operation time. From the perspective of compatibility, the catalyst is macroscopically an oily liquid, which is naturally compatible with the oily system of waste mineral oil. It can form a uniform slurry system in the slurry bed without the need for additional dispersants, eliminating the local reaction dead zones caused by uneven dispersion of traditional particulate catalysts, and perfectly meeting the process requirements of "solid-liquid homogeneous contact" in slurry beds.

[0071] In terms of industrial application value, this application further lowers the threshold and cost for technology implementation. On the one hand, the sulfidation process of the catalyst can be completed simultaneously under slurry bed reaction conditions, eliminating the need for a separate pre-sulfidation process, simplifying the process flow, and reducing equipment investment and operating steps. On the other hand, it has strong compatibility with reaction conditions and can function stably within the range of conventional slurry bed hydrogenation process parameters, without requiring large-scale modifications to existing production equipment, thus reducing the technology upgrade costs for enterprises. Simultaneously, the catalyst can efficiently convert ineffective components in waste mineral oil into products with high market demand, such as diesel and lubricating oil base oil, not only enhancing the recycling value of resources but also reducing waste emissions, thus balancing economic and environmental benefits.

[0072] Overall, the advantage of this application is not an improvement in a single step, but an optimization of the entire chain from molecular design, preparation process, structure construction to application adaptation: it solves the core problem of active phase dispersion and stability through precise preparation control, balances catalytic activity and system compatibility through innovative core-shell structure, and achieves a unity of "technological advancement" and "industrial feasibility" by adapting to slurry bed process and simplifying operation. Ultimately, it effectively overcomes the pain points of existing waste mineral oil regeneration processes, such as easy coking, short continuous operation, insufficient recovery of effective components, and difficulty in equipment adaptation, and provides a set of efficient, stable and economical technical solutions for waste mineral oil regeneration.

[0073] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then common international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0074] Example 1

[0075] By weight, the catalyst for the slurry bed of waste mineral oil in this embodiment is composed of the following raw materials: ammonium heptamolybdate: 8.0 parts, isooctanoic acid: 25.0 parts, cobalt isooctanoate: 1.5 parts, acetic anhydride: 10.0 parts, elemental sulfur: 0.8 parts, hexadecyltrimethylammonium bromide (CTAB): 0.5 parts, and aminopropyltriethoxysilane (APS): 1.0 parts.

[0076] Based on the above raw materials, this embodiment also provides the preparation steps of a slurry bed catalyst for waste mineral oil:

[0077] S1. Precursor Complexation and Micellar Assembly: The above-mentioned amounts of ammonium heptamolybdate, isooctanoic acid, cobalt isooctanoate, acetic anhydride, elemental sulfur, and CTAB were added to a 500 mL four-necked flask equipped with a stirrer, thermometer, and reflux condenser. Under atmospheric pressure and nitrogen protection, the stirring was started and the temperature was raised to 80 °C, and the reaction was maintained at this temperature for 1.5 h. After the reaction was completed, a homogeneous first reaction system containing micellar assemblies was obtained.

[0078] S2. Introduction and Functionalization of Acidic Sites: The temperature of the first reaction system was raised to 130℃. Then, APS was slowly added dropwise to the system using a constant-pressure dropping funnel, controlling the dropping rate to be completed within 30 minutes. After the addition was complete, the reaction was continued at 130℃ with stirring for 2 hours. During this process, the amino groups of APS coordinated with the metal centers in the micelle assemblies, while their ethoxy groups hydrolyzed and condensed, initially forming a siloxane interface layer around the metal centers, resulting in the second reaction system containing intermediates.

[0079] S3. Sulfidation and Structural Solidification: The temperature of the second reaction system was further increased to 190°C, and a sulfidation reaction was carried out at 190°C for 3 hours. During this stage, elemental sulfur reacted with the molybdenum-cobalt precursor to generate a Co-Mo-S active phase with a nano-thin layer structure in situ; simultaneously, the siloxane interface layer formed by APS further crosslinked and solidified into a stable silicon-oxygen network. After the reaction was completed, heating was stopped, and the mixture was allowed to cool naturally to room temperature (approximately 25°C) to obtain a dark brown, homogeneous, and transparent oily liquid, which is the target catalyst of this embodiment.

[0080] Catalyst metal content: ICP-OES analysis showed that the mass fraction of molybdenum (Mo) in the catalyst was 18.5% and the mass fraction of cobalt (Co) was 2.2%.

[0081] Catalyst microstructure: Before SEM testing, a small amount of oily liquid catalyst is diluted with n-hexane and ultrasonically dispersed to reduce the viscosity of the oil phase; then, a clean silicon wafer is used as the substrate, and the diluted solution is dropped onto the substrate using a micropipette, and the solvent is allowed to evaporate naturally at room temperature until dry; finally, in order to eliminate charge accumulation during testing, the dried sample needs to be sent to an ion sputtering instrument to deposit a 5-10 nm thick gold or carbon film on the surface to complete the conductivity treatment before it can be used for SEM testing.

[0082] Before TEM testing, the catalyst is first diluted with n-hexane to a higher concentration and ensured to be uniformly dispersed. Then, a microgrid support with an ultrathin carbon film is selected, and a small amount of the diluted solution is dropped onto the surface of the carbon film. After standing for a moment, the nanoparticles are allowed to adsorb. After the solvent has initially evaporated, fresh n-hexane is added for rapid rinsing, followed by further natural drying. Finally, the dried support is placed in a dedicated sample box for TEM analysis. Through the above pretreatment, the oily catalyst can be transformed into a sample suitable for TEM testing.

[0083] Figure 2 This is a SEM image of the active component of the catalyst product provided in Example 1 of this application.

[0084] like Figure 2 As shown, the active component sample particles exist in a spherical shape, and analysis shows that the diameter of the catalyst particles is approximately 100 nm.

[0085] Figure 3 This is a TEM image of the active component of the catalyst product provided in Example 1 of this application.

[0086] like Figure 3 As shown, the active component of the catalyst exhibits a distinct core-shell structure, with several aggregated Co-Mo-S nanosheets encapsulated within the shell. Simultaneously, the active component demonstrates a rich porous structure, indicating a large specific surface area, which can enhance the catalytic effect.

[0087] Catalyst oil solubility: At 25°C, in hydrocracking base oil (density 0.89 g / cm³) 3 Kinematic viscosity 35mm 2 In the presence of 40 g / L, its maximum solubility can reach 40 g / L. After complete dissolution, it forms a dark brown, uniform, transparent oily liquid with no visible particles.

[0088] Catalyst dispersion stability: The catalyst was dispersed in the above base oil at a mass fraction of 1.5%. After standing at room temperature for 72 hours, the system showed no stratification or precipitation. Dynamic light scattering detection showed that the particle size distribution remained within the range of 80~120 nm. Compared with the initial dispersion state (average particle size of 100 nm), the fluctuation was less than 5%, indicating that it can maintain good dispersibility in the slurry bed reaction system.

[0089] Example 2

[0090] By weight, the catalyst used in the waste mineral oil slurry bed in this embodiment is composed of the following raw materials: molybdic acid: 6.0 parts, isooctanoic acid: 20.0 parts, cobalt isooctanoate: 1.0 parts, propionic anhydride: 8.0 parts, dimethyl disulfide: 1.2 parts, hexadecyltrimethylammonium bromide (CTAB): 0.3 parts, and aminopropyltriethoxysilane (APS): 0.8 parts.

[0091] Based on the above raw materials, this embodiment also provides the preparation steps of a slurry bed catalyst for waste mineral oil:

[0092] S1. Precursor complexation and micelle assembly: Add the above raw materials to a 500mL four-necked flask, stir and heat to 60℃ under normal pressure and nitrogen protection, and react at a constant temperature for 1h to obtain the first reaction system containing micelle assemblies.

[0093] S2. Introduction and functionalization of acidic sites: The system was heated to 110°C, and APS was added dropwise over 20 minutes using a constant pressure dropping funnel. The reaction was then continued at 110°C for 1 hour to allow APS coordination and hydrolysis-condensation to proceed simultaneously, resulting in a second reaction system containing intermediates.

[0094] S3. Sulfidation and Structural Curing: The system was heated to 170℃ and the sulfidation reaction was carried out for 2 hours. Dimethyl disulfide reacted with the metal precursor to generate the Co-Mo-S active phase, and the silicon-oxygen network was simultaneously cured. After cooling to room temperature, a dark brown homogeneous oily liquid catalyst was obtained.

[0095] Catalyst metal content: ICP-OES analysis showed that the mass fraction of Mo in CAT-2 was 12.3% and the mass fraction of Co was 1.1%.

[0096] Example 3

[0097] By weight, the catalyst used in the waste mineral oil slurry bed in this embodiment is composed of the following raw materials: molybdenum trioxide: 10.0 parts, isooctanoic acid: 30.0 parts, cobalt isooctanoate: 2.0 parts, acetic anhydride: 12.0 parts, thioacetamide: 2.0 parts, hexadecyltrimethylammonium bromide (CTAB): 0.8 parts, and aminopropyltriethoxysilane (APS): 1.5 parts.

[0098] Based on the above raw materials, this embodiment also provides the preparation steps of a slurry bed catalyst for waste mineral oil:

[0099] S1. Precursor complexation and micelle assembly: Add the above raw materials to a 500 mL four-necked flask, stir and heat to 100 °C under normal pressure and nitrogen protection, and react at a constant temperature for 2 h to obtain the first reaction system containing micelle assemblies.

[0100] S2. Introduction and functionalization of acidic sites: The system was heated to 150°C, and APS was added dropwise over 40 minutes using a constant pressure dropping funnel. The reaction was then continued at 150°C for 3 hours to obtain a second reaction system containing the intermediate.

[0101] S3. Sulfidation and Structural Curing: The system was heated to 220℃ and the sulfidation reaction was carried out for 4 hours to generate the Co-Mo-S active phase and complete the curing of the silicon-oxygen network. After cooling to room temperature, a dark brown homogeneous oily liquid catalyst was obtained.

[0102] Catalyst metal content: ICP-OES analysis showed that the mass fraction of Mo in CAT-3 was 28.7% and the mass fraction of Co was 4.8%.

[0103] Example 4

[0104] By weight, the catalyst used in the waste mineral oil slurry bed in this embodiment is composed of the following raw materials: ammonium heptamolybdate: 7.0 parts, isooctanoic acid: 28.0 parts, cobalt isooctanoate: 1.8 parts, acetic anhydride: 9.0 parts, elemental sulfur: 1.5 parts, hexadecyltrimethylammonium bromide (CTAB): 0.6 parts, and aminopropyltriethoxysilane (APS): 1.2 parts.

[0105] Based on the above raw materials, this embodiment also provides the preparation steps of a slurry bed catalyst for waste mineral oil:

[0106] S1. Precursor complexation and micelle assembly: The above raw materials were added to a 500mL four-necked flask, stirred and heated to 90℃ under normal pressure and nitrogen protection, and reacted at a constant temperature for 1.2h to obtain the first reaction system containing micelle assemblies.

[0107] S2. Introduction and functionalization of acidic sites: The system was heated to 140°C, and APS was added dropwise over 35 minutes using a constant pressure dropping funnel. The reaction was then continued at 140°C for 2.5 hours to obtain a second reaction system containing the intermediate.

[0108] S3. Sulfidation and Structural Solidification: The system was heated to 200℃ and the sulfidation reaction was carried out for 3.5 h to generate the Co-Mo-S active phase and complete the solidification of the silicon-oxygen network. After cooling to room temperature, a dark brown homogeneous oily liquid catalyst was obtained.

[0109] Catalyst metal content: ICP-OES analysis showed that the mass fraction of Mo in CAT-4 was 15.6% and the mass fraction of Co was 3.5%.

[0110] Comparative Example 1

[0111] This comparative example is modified from the one disclosed in Example 1 as follows:

[0112] Without the addition of hexadecyltrimethylammonium bromide (CTAB), the other raw materials, proportions, and preparation steps are exactly the same as in Example 1.

[0113] Comparative Example 2

[0114] This comparative example is modified from the one disclosed in Example 1 as follows:

[0115] Without adding aminopropyltriethoxysilane (APS), the other raw materials, proportions, and preparation steps are exactly the same as in Example 1.

[0116] Comparative Example 3

[0117] This comparative example is modified from the one disclosed in Example 1 as follows:

[0118] Cobalt isooctanoate was not added, and the amount of ammonium heptamolybdate was increased to 9.5 parts (to keep the total molar amount of metal approximately unchanged). The other raw material types, ratios and preparation steps were exactly the same as in Example 1.

[0119] Comparative Example 4

[0120] This comparative example is modified from the one disclosed in Example 1 as follows:

[0121] Elemental sulfur is not added, and the S3 sulfidation reaction step is omitted. After completing the S2 step, the second reaction system is directly cooled to room temperature to obtain the product.

[0122] Comparative Example 5

[0123] This comparative example is modified from the one disclosed in Example 1 as follows:

[0124] Acetic anhydride was not added, and the other raw materials, proportions, and preparation steps were exactly the same as in Example 1.

[0125] Application examples

[0126] The catalysts obtained in Examples 1-4 and Comparative Examples 1-5 were added to representative waste mineral oils, and slurry-bed hydrogenation reactions were carried out under the same conditions: reaction temperature of 380°C, reaction pressure (hydrogen partial pressure) of 6.0 MPa, reaction time of 2 h, hydrogen-to-oil ratio of 1000:1, and catalyst (stock solution) addition of 0.20 wt%. The properties of the oil before and after the reaction are compared in Tables 1 and 2. Meanwhile, the catalyst in this application has undergone in-situ pre-sulfurization in the preparation stage (S3) through the addition of sulfur-containing compounds, forming a complete Co-Mo-S active phase structure. In subsequent slurry-bed applications, it further utilizes the sulfur in the waste oil to achieve self-sulfurization and dynamic sulfur replenishment to maintain long-term stability.

[0127] Table 1. Comparison of oil properties before and after slurry-bed hydrotreating of catalysts in Examples 1-4.

[0128]

[0129] It should be noted that after the catalyst of Example 1 was continuously operated in the slurry bed hydrodesulfurization process for 7.5 months (225 days), the key indicators were as follows: the activity retention rate reached 92%. The metal loss was detected by inductively coupled plasma optical emission spectroscopy (ICP-OES). The loss of cobalt (Co) was 0.08 wt%, and the loss of molybdenum (Mo) was only 0.05 wt%, with no obvious loss of active components.

[0130] As shown in Table 1, by comparing the data of waste mineral oil feedstock, blank experiment without catalyst, and hydrogenation reaction data of Examples 1-4, it can be clearly seen that the catalyst of this application exhibits significant and comprehensive technical effects in the slurry bed hydrogenation regeneration of waste mineral oil.

[0131] In terms of deep purification and impurity removal, compared with the raw material and blank experiment, the density (20°C) of the products in each example decreased from 865.6 kg / m³ of the raw material to 843.2–845.1 kg / m³. 3 The sulfur content decreased from 2576 mg / kg in the raw material to 755-778 mg / kg, the nitrogen content decreased from 731 mg / kg to 502-521 mg / kg, the chlorine content decreased significantly from 339.9 mg / kg to 8.2-9.1 mg / kg, and the total metal content decreased sharply from 2831.79 mg / kg to 15.37-18.05 mg / kg. The impurity removal effect far exceeded that of the blank experiment, especially the ability to remove chlorine and metals, laying a key foundation for the production of high-quality base oil.

[0132] Regarding efficient conversion and coking suppression capabilities, group composition data show that the raw material contains 4.72 wt% gum and 1.93 wt% asphaltenes. The blank experiment still contains 4.32 wt% gum and 0.49 wt% asphaltenes, while the gum content in each embodiment is only 1.0-1.03 wt% and the asphaltenes content is 0. At the same time, the saturated hydrocarbon content increases from 90.39 wt% in the raw material to 96.39-96.65 wt%, and the aromatic hydrocarbon content remains at a low level. This indicates that the catalyst can efficiently convert easily coking gum and asphaltenes into ideal components through the synergistic effect of "cracking-hydrogenation", thereby inhibiting coking formation from the source.

[0133] In terms of high-value product yield, the high-viscosity base oil (120BS) yield in the blank experiment was only 5.2 wt%, and the total yield of ideal components was 91.37 wt%. However, the 120BS yield in each example was increased to 11.3-11.8 wt%, and the total yield of ideal components reached 98.6-98.65 wt%. The high-value product yield doubled, and the resource utilization rate was greatly improved.

[0134] Regarding the stability of device operation, the continuous operation time of the blank experiment device was only 1.5 months, while the continuous operation time of each embodiment using the catalyst of this application was extended to 6 to 8 months, and Example 3 even reached 7 to 9 months. This directly verifies the excellent coking ability and structural stability of the catalyst, and completely solves the core pain point of the prior art that the device cannot operate for a long period of time.

[0135] Furthermore, although the raw material ratios and process parameters of Examples 1 to 4 differ, the performance data of the final products are highly consistent and all at an excellent level, which fully demonstrates that the technical solution of the present invention has good universality and robustness and is a reliable technical platform.

[0136] Table 2 Comparison of oil properties before and after slurry-bed hydrotreating with catalysts from Comparative Examples 1–5

[0137]

[0138] As shown in Table 2, Comparative Example 1 lacked a crucial structure-directing agent due to the absence of cetyltrimethylammonium bromide (CTAB). The core function of CTAB is to self-assemble into a micelle template during the preparation process, providing confined space for the dispersion of the metal precursor and the growth of the active phase. Without this template, the metal precursor cannot achieve uniform nanoscale dispersion, resulting in severe aggregation of the final active components. This leads to a significant decrease in the catalyst's specific surface area and a substantial increase in mass transfer resistance during the reaction. Performance data shows that its sulfur content (1050 mg / kg), chlorine content (85.5 mg / kg), and total metal content (205.7 mg / kg) are all significantly higher than in Example 1, while the gum content still reaches 3.15 wt%, and the ideal total yield is only 93.5 wt%. This clearly demonstrates that due to the aggregation of active components, the catalyst's hydrorefining ability (desulfurization, dechlorination, and demetallization) and gum asphaltenes conversion ability are significantly weakened, ultimately resulting in poor overall performance.

[0139] Comparative Example 2, lacking the addition of aminopropyltriethoxysilane (APS), directly lacked the source of acidic sites and the foundation for constructing the silicon-oxygen network. APS plays a dual role in the catalyst, providing acidic sites and forming a stable shell. These acidic sites are crucial for the initial cracking of heavy components such as gums and asphaltenes. Through the catalytic cracking action of these acidic sites, complex heavy molecules are broken down into smaller, easily hydrogenated fragments, which are then further converted by the hydrogenation active phase. Without acidic sites, the catalyst's cracking function is lost. Even with adequate hydrogenation activity, it cannot effectively process heavy components, resulting in a gum content as high as 2.95 wt% in the product and a high-viscosity base oil (120BS) yield of only 7.1 wt%, far lower than the 11.8 wt% in Example 1. This fully demonstrates the indispensability of the acidic sites provided by APS for the conversion of heavy components and improving the yield of high-value products. The absence of CTAB in Comparative Example 1 directly undermined the foundation of the nanostructure, leading to a complete collapse in performance. In contrast, the absence of APS in Comparative Example 2 primarily weakened the cracking function, but the hydrogenation function remained intact.

[0140] Comparative Example 3, lacking cobalt isooctanoate and maintaining the total metal molar amount solely by increasing ammonium heptamolybdate, failed to form the highly active Co-Mo-S phase. Cobalt acts as an "electron promoter" in the catalytic system; its embedding into the edges of MoS2 nanosheets lowers the H2 dissociation barrier by regulating the electronic structure, significantly enhancing hydrogenation activity. Without cobalt, the catalyst can only form a single MoS2 phase, resulting in a substantial decrease in intrinsic hydrogenation activity. Data shows that its sulfur content (1102 mg / kg) and chlorine content (91.6 mg / kg) were among the worst in the comparative examples, and its high-viscosity base oil yield was only 6.5 wt%, the lowest of all comparative examples. Furthermore, its ability to capture free radicals was weak. This further illustrates that the synergistic promoting effect of cobalt is crucial for improving catalyst hydrogenation efficiency and ensuring the generation of high-value products; its absence prevents the fulfillment of the requirements for deep hydrogenation of waste mineral oil.

[0141] Comparative Example 4, by omitting elemental sulfur and the S3 sulfidation step, completely blocked the formation pathway of the active phase. The core of the sulfidation process is the conversion of the metal precursor (an organic complex of Mo and Co) into a hydrogenation-active Co-Mo-S phase. However, without a sulfur source and the sulfidation step, the metal precursor remained in its original form, failing to form any effective hydrogenation-active phase. Consequently, all its performance indicators deteriorated: density (858.1 kg / m³) 3 The sulfur content (2250 mg / kg), chlorine content (305.2 mg / kg), and total metal content (2501.5 mg / kg) were all close to the levels of waste mineral oil feedstock. The gum content rose to 5.21 wt%, and asphaltenes were not effectively removed. The ideal total yield was only 90.96 wt%, even approaching the performance of the blank experiment (without catalyst). This directly proves that the sulfidation step and sulfur source are prerequisites for the formation of the active phase of the catalyst; without them, the catalyst is almost completely ineffective.

[0142] Comparative Example 5, lacking acetic anhydride, resulted in an incomplete and insufficient complexation reaction between the metal and isooctanoic acid. Acetic anhydride, acting as a "dehydrating agent," can remove water generated during the complexation reaction, shifting the reaction equilibrium towards the formation of a metal-organic acid precursor. This ensures sufficient coordination between metal ions and isooctanoic acid, forming a structurally uniform precursor. Without acetic anhydride, residual water in the system inhibits the complexation reaction, leading to an imperfect precursor structure and uneven dispersion. This ultimately affects the morphology and dispersibility of the active phase, resulting in uneven size and some metal ions failing to participate in active phase formation, thus wasting active sites. Data shows that its sulfur content (1187 mg / kg) and total metal content (215.4 mg / kg) are higher than Example 1, while its gum content is 3.32 wt%, and the ideal component yield is 93.33 wt%. All performance aspects are significantly inferior to Example 1, fully demonstrating the importance of acetic anhydride in driving the complete complexation reaction and constructing an ideal precursor structure; its absence prevents the formation of a highly efficient catalytic system.

[0143] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0144] Furthermore, in the description of this application, the terms "comprising," "including," etc., mean "including but not limited to." 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.

[0145] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing a catalyst for the regeneration of waste mineral oil, characterized in that, The method includes the following steps: S1. Molybdenum source, isooctanoic acid, cobalt isooctanoate, organic acid anhydride, sulfur-containing compound and hexadecyltrimethylammonium bromide are mixed and then subjected to a preliminary complexation reaction at 50-110℃ for 0.5-2h to obtain a first reaction system containing micelle assemblies. S2. Raise the temperature of the first reaction system to 110-160°C, then add aminopropyltriethoxysilane to the first reaction system and react at 110-160°C for 1-3 hours, so that the aminopropyltriethoxysilane can be coordinated and hydrolyzed on the micelle assembly simultaneously to obtain a second reaction system containing an intermediate. S3. The temperature of the second reaction system is further increased to 160-230°C, and the sulfurization reaction is carried out at 160-230°C for 2-4 hours, so that the intermediate is converted in situ into a catalyst with a Co-Mo-S active phase and a silicon-oxygen network structure. The catalyst, by mass, is composed of the following chemical raw materials: molybdenum source: 6-10 parts, isooctanoic acid: 20-30 parts, cobalt isooctanoate: 1-2 parts, organic acid anhydride: 8-12 parts, sulfur-containing compound: 0.5-2 parts, hexadecyltrimethylammonium bromide: 0.3-0.8 parts, and aminopropyltriethoxysilane: 0.5-1.5 parts; The organic acid anhydride includes at least one of acetic anhydride and propionic anhydride; The catalyst contains 10-30% molybdenum and 1-5% cobalt by mass fraction.

2. The method for preparing the catalyst for waste mineral oil regeneration according to claim 1, characterized in that, The molybdenum source includes at least one of ammonium molybdate, molybdic acid, and molybdenum trioxide.

3. The method for preparing the catalyst for waste mineral oil regeneration according to claim 1, characterized in that, The sulfur-containing compound includes at least one of elemental sulfur, dimethyl disulfide, and thioacetamide.

4. A catalyst for the regeneration of waste mineral oil prepared by the method according to any one of claims 1 to 3.

5. The catalyst for waste mineral oil regeneration according to claim 4, characterized in that, The active component of the catalyst product is a core-shell nanocomposite material. The core layer is a Co-Mo-S hydrogenated active phase, and the shell layer is an organic-inorganic hybrid layer composed of isooctanoic acid derivatives and a silicon-oxygen network.

6. The catalyst for waste mineral oil regeneration according to claim 5, characterized in that, The Co-Mo-S hydrogenation active phase exists in the form of nanosheets, and the length of the nanosheets is 5-15 nm, with 2-4 stacked layers.

7. The application of the catalyst for waste mineral oil regeneration according to any one of claims 4 to 6, characterized in that, The catalyst is used in a slurry-bed hydrogenation process for waste mineral oil, and the mass of the catalyst added is 0.05 to 0.3% of the mass of the waste mineral oil.

8. The application of the catalyst for waste mineral oil regeneration according to claim 7, characterized in that, The slurry-bed hydrogenation process includes the following parameters: reaction temperature of 320–400℃, hydrogen partial pressure of 5.0–16.0 MPa, reaction time of 1–3 h, and hydrogen-to-oil ratio of (600–1500):1.

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