Waste hydrogenation catalyst treatment methods and plastic liquefaction catalysts and their applications

Abstract

This invention provides a method for treating waste hydrogenation catalysts and a plastic liquefaction catalyst, as well as their applications. The method for treating waste hydrogenation catalysts includes: S1, subjecting a first mixed system containing waste hydrogenation catalyst, water, and a silicon source to a first reaction at 150–200°C; S2, then cooling to 80–100°C, adding glucose and an iron source, and maintaining the temperature at 80–100°C to conduct a second reaction; S3, then performing a first solid-liquid separation, calcining the obtained first solid product to obtain a catalyst precursor; S4, subjecting the catalyst precursor to sulfidation treatment to obtain a plastic liquefaction catalyst. This invention utilizes waste hydrogenation catalysts to prepare highly active plastic liquefaction catalysts, achieving efficient utilization of waste hydrogenation catalysts.

Description

Technical Field

[0001] This invention relates to the field of waste resource recycling, specifically to a method for treating waste hydrogenation catalysts and a plastic liquefaction catalyst and its application. Background Technology

[0002] Currently, plastic products are widely used, leading to increasingly serious pollution, making the recycling of plastic waste essential. Methods for treating plastic waste mainly include mechanical processing, biological treatment, pyrolysis, and chemical conversion using chemical additives. Among these, pyrolysis of plastic waste, processing it at high temperatures into liquid hydrocarbons that can be used as fuels or industrial raw materials, is an important pathway to achieving high-value conversion of plastic waste and has gradually attracted widespread attention. The pyrolysis temperature of plastic waste is typically as high as 500–900℃. Using a plastic liquefaction catalyst for thermal liquefaction is crucial for reducing its pyrolysis temperature, shortening pyrolysis time, and improving pyrolysis efficiency. Therefore, there is an urgent need to develop highly active plastic liquefaction catalysts.

[0003] In addition, hydrotreating is a common treatment method for oil products. It mainly involves hydrotreating oil products under the action of a hydrotreating catalyst. After hydrotreating, the hydrotreating catalyst is deactivated and forms waste hydrotreating catalyst. How to achieve efficient utilization of waste hydrotreating catalyst is also an important issue currently being addressed. Summary of the Invention

[0004] This invention provides a method for treating waste hydrogenation catalysts and a plastic liquefaction catalyst and its application. It utilizes waste hydrogenation catalysts to prepare highly active plastic liquefaction catalysts, thus achieving efficient utilization of waste hydrogenation catalysts.

[0005] In one aspect, the present invention provides a method for treating waste hydrogenation catalyst, comprising: S1, subjecting a first mixed system containing waste hydrogenation catalyst, water, and silicon source to a first reaction at 150-200°C; S2, then cooling to 80-100°C, adding glucose and iron source thereto, and maintaining the temperature at 80-100°C to carry out a second reaction; S3, then performing a first solid-liquid separation, calcining the obtained first solid product to obtain a catalyst precursor; S4, subjecting the catalyst precursor to sulfidation treatment to obtain a plastic liquefaction catalyst.

[0006] According to one embodiment of the present invention, in the first mixed system, the mass of the water is 2 to 5 times the mass of the waste hydrogenation catalyst; and / or, the mass ratio of the silicon source to the waste hydrogenation catalyst is 1:(10 to 20); and / or, the silicon source includes silica sol.

[0007] According to one embodiment of the present invention, the first reaction process includes: mixing waste hydrogenation catalyst, water, and silicon source to form the first mixed system, starting stirring, heating to 150-200°C under stirring conditions at a stirring rate of 100-300 r / min, and holding at the temperature for 10-20 h.

[0008] According to one embodiment of the present invention, the mass ratio of glucose to the waste hydrogenation catalyst is 1:(10-20); and / or, the mass ratio of iron source to the waste hydrogenation catalyst is 1:(10-20); and / or, the iron source comprises a soluble iron salt, wherein the soluble iron salt comprises ferric nitrate.

[0009] According to one embodiment of the present invention, the second reaction process includes: maintaining a constant temperature of 80-100°C for 4-6 hours under a stirring state with a stirring rate of 50-100 r / min.

[0010] According to one embodiment of the present invention, the first solid-liquid separation process includes: allowing the system after the second reaction to stand at 50-60°C for 5-10 hours to separate the first solid product therein.

[0011] According to one embodiment of the present invention, the first solid product is dried at 100-180°C for 4-6 hours before being calcined.

[0012] According to one embodiment of the present invention, the calcination conditions are: calcination temperature of 450-550°C and calcination time of 3-5 hours.

[0013] According to one embodiment of the present invention, the catalyst precursor is pulverized to 50-150 mesh and then subjected to the sulfidation treatment.

[0014] According to one embodiment of the present invention, the vulcanization process includes: mixing the catalyst precursor with sulfur, dimethyl disulfide, ethanolamine, and distillate oil with a distillation range of 180-290°C, and reacting the mixture at 0.1-0.3 MPa and 200-250°C for 3-5 hours under stirring conditions at a stirring rate of 100-300 r / min to obtain the plastic liquefaction catalyst.

[0015] According to one embodiment of the present invention, the mass ratio of sulfur to catalyst precursor is 1:(10-50), the mass ratio of dimethyl disulfide to catalyst precursor is 1:(5-25), the mass ratio of ethanolamine to catalyst precursor is (1-3):100, and the mass ratio of distillate oil to catalyst precursor is (2-4):1.

[0016] According to one embodiment of the present invention, after the vulcanization treatment is completed, a product of 50-150 mesh is formed by spray drying to obtain the plastic liquefaction catalyst; or, after the vulcanization treatment is completed, solid-liquid separation is performed, the obtained second solid product is dried and then pulverized to 50-150 mesh to obtain the plastic liquefaction catalyst.

[0017] According to one embodiment of the present invention, the waste hydrogenation catalyst includes an alumina support, and a metal component, a carbon component, and a sulfur component supported on the alumina support.

[0018] In another aspect, the present invention provides a plastic liquefaction catalyst, which is prepared according to the above method.

[0019] In another aspect, the present invention provides a method for pyrolyzing plastics, comprising pyrolyzing the plastics under the action of the aforementioned plastic liquefaction catalyst.

[0020] In this invention, through the above preparation process, a plastic liquefaction catalyst suitable for plastic pyrolysis is obtained using waste hydrogenation catalyst, which reduces the preparation cost of plastic liquefaction catalyst, realizes the efficient utilization of waste hydrogenation catalyst, avoids the loss of heavy metals such as Mo, W, Co, and Ni contained in waste hydrogenation catalyst, and can avoid environmental pollution caused by these heavy metals.

[0021] Meanwhile, the plastic liquefaction catalyst obtained by the present invention through the above process has high activity, good stability, good dispersibility in the plastic liquefaction process, and good bond cleavage selectivity. Using this plastic liquefaction catalyst to catalyze the cleavage of plastics can improve the plastic cleavage efficiency, reduce the cleavage temperature and reaction severity, reduce energy consumption, and shorten the cleavage time, which is of great significance for practical industrial applications. At the same time, it can improve the liquid yield (the liquid yield can reach more than 80%), especially the yield of low-range liquid products (i.e., low-range fractions) (the mass proportion of fractions with a distillation range of less than 350°C in the liquid products produced by cleavage can be as high as 70% or more), and can reduce the residue rate, that is, reduce the solid product yield (less than 5%).

[0022] Furthermore, the waste hydrogenation catalyst treatment method of this invention has advantages such as low energy consumption, simple process, and readily available operation.

[0023] Furthermore, this invention simultaneously achieves the efficient utilization and treatment of two types of waste: waste hydrogenation catalysts and plastic waste, and effectively solves the environmental pollution problems caused by these wastes. Attached Figure Description

[0024] Figure 1 The image shows a SEM image of Cat-1 obtained in Example 1.

[0025] Figure 2The image shows the XRD pattern of Cat-1 obtained in Example 1. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] In the description of this invention, terms such as "first" and "second" are used for descriptive purposes only, such as to distinguish between components to more clearly illustrate / explain the technical solution, and should not be construed as indicating or implying the number of technical features indicated or the order of features with substantial significance.

[0028] This invention provides a method for treating waste hydrogenation catalyst, comprising the following steps:

[0029] S1. The first mixed system containing waste hydrogenation catalyst, water and silicon source is subjected to the first reaction at 150-200℃ (i.e. the first reaction temperature is 150-200℃).

[0030] For example, the first reaction temperature can be a range of 150°C, 160°C, 170°C, 180°C, 190°C, 200°C or any combination thereof.

[0031] The first reaction can be carried out under stirring, with a stirring rate of 100–300 r / min, for example, 100 r / min, 120 r / min, 150 r / min, 180 r / min, 200 r / min, 220 r / min, 250 r / min, 280 r / min, 300 r / min, or any combination thereof. The first reaction time can be 10–20 h, for example, 10 h, 12 h, 15 h, 18 h, 20 h, or any combination thereof.

[0032] In some embodiments, the first reaction process may include: mixing the waste hydrogenation catalyst, water, and silicon source to form a first mixed system, starting stirring, heating to the first reaction temperature (i.e., 150-200°C) under stirring conditions at a stirring rate of 100-300 r / min, and holding the temperature for 10-20 h (i.e., the first reaction time is 10-20 h).

[0033] Furthermore, the first reaction can be carried out under air atmosphere and atmospheric pressure conditions, such as in an atmospheric pressure reactor. In specific implementation, waste hydrogenation catalyst can be added to an atmospheric pressure reactor, along with water and a silicon source (forming a first mixed system). Then, stirring is started (stirring rate of 100–300 r / min), and the temperature is increased while stirring until the first reaction temperature is reached. The temperature is then maintained at the first reaction temperature for a preset time (i.e., the first reaction time) to complete the first reaction.

[0034] Specifically, in the first mixing system, the mass of water can be 2 to 5 times the mass of the spent hydrogenation catalyst (i.e., the mass ratio of water to spent hydrogenation catalyst is (2 to 5): 1), for example, a range of 2, 2.5, 3, 3.5, 4, 4.5, 5, or any combination thereof. The water used includes, for example, deionized water.

[0035] In addition, the mass ratio of silicon source to spent hydrogenation catalyst can be 1:(10-20), for example, 1:10, 1:12, 1:15, 1:18, 1:20 or any combination thereof.

[0036] The silicon source may include silica sol, such as silica sol with a silica content (by mass) of 40 wt%, but is not limited thereto.

[0037] The first reaction process involves hydrothermal treatment of the waste hydrogenation catalyst, which can make the active components more uniformly dispersed. At the same time, silicon is added to further regulate the structure and other characteristics of the catalyst, which is beneficial for its cooperation with subsequent steps to produce a highly active plastic liquefaction catalyst.

[0038] S2. Then cool down to 80-100℃, add glucose and iron source, and maintain 80-100℃ for the second reaction (i.e., the temperature of the second reaction is 80-100℃).

[0039] For example, the temperature of the second reaction can be a range of 80°C, 85°C, 90°C, 95°C, 100°C or any combination thereof.

[0040] The second reaction can be carried out under stirring, and the reaction time can be 4 to 6 hours, for example, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours or any combination thereof.

[0041] In some embodiments, the second reaction process includes: maintaining a constant temperature (i.e., 80-100°C) for 4-6 hours (i.e., reaction time is 4-6 hours) under a stirring state of 50-100 r / min.

[0042] The stirring rate is, for example, a range of 50 r / min, 55 r / min, 60 r / min, 65 r / min, 70 r / min, 75 r / min, 80 r / min, 85 r / min, 90 r / min, 95 r / min, 100 r / min or any two of these.

[0043] In practice, after the first reaction is completed, the temperature is lowered to the second reaction temperature. Glucose and iron source are added sequentially to the reactor where the first reaction is carried out, and the stirring speed is adjusted to 50-100 r / min. Then, the reactor is kept at the second reaction temperature for a preset time (i.e., the second reaction time) to complete the second reaction.

[0044] Specifically, the amount of glucose added satisfies the following condition: the mass ratio of glucose to waste hydrogenation catalyst is 1:(10-20), for example, 1:10, 1:12, 1:15, 1:18, 1:20 or any combination thereof.

[0045] In addition, the amount of iron source added satisfies the following: the mass ratio of iron source to waste hydrogenation catalyst is 1:(10-20), for example, 1:10, 1:12.5, 1:15, 1:18, 1:20 or any combination thereof.

[0046] The iron source can include soluble iron salts, specifically ferric salts, such as ferric nitrate.

[0047] The second reaction process can supplement iron to the hydrogenation catalyst and further regulate the structure and other characteristics of the catalyst, which is beneficial for its cooperation with subsequent steps to obtain a highly active plastic liquefaction catalyst.

[0048] S3. Then, the first solid-liquid separation is performed, and the first solid product is calcined to obtain the catalyst precursor.

[0049] Specifically, the first solid-liquid separation can be carried out at 50-60°C, which is beneficial to further optimize the performance of the prepared plastic liquefaction catalyst. For example, in some preferred embodiments, the first solid-liquid separation process includes: letting the system after the second reaction stand at 50-60°C for 5-10 hours (i.e., standing temperature is 50-60°C and standing time is 5-10 hours) to separate the first solid product therein.

[0050] In practice, after the second reaction is completed, the system is cooled to the above-mentioned settling temperature and stirring is stopped. Then, it is allowed to stand for 5 to 10 hours, and the solid and liquid are separated. The resulting solid is the first solid product.

[0051] For example, the settling temperature is a range of 50°C, 52°C, 55°C, 58°C, 60°C or any two of these, and the settling time is a range of 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, 10h or any two of these.

[0052] Generally, the first solid product can be dried first before the above-mentioned calcination. The drying temperature can be 100-180℃, for example, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃ or any combination thereof. The drying time can be 4-6h, for example, 4h, 4.5h, 5h, 5.5h, 6h or any combination thereof.

[0053] In addition, the above-mentioned roasting conditions can be: a roasting temperature of 450 to 550°C, for example, 450°C, 480°C, 500°C, 520°C, 550°C or any combination thereof, and a roasting time of 3 to 5 hours, for example, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours or any combination thereof.

[0054] S4. The catalyst precursor is subjected to sulfurization treatment to obtain a plastic liquefaction catalyst.

[0055] By sulfiding the catalyst precursor, at least some of the active metals in the catalyst can be transformed from the oxidized state to the sulfidated state, generating an active phase with better catalytic activity for plastic liquefaction (such as MoS2, WS2, NiS3, Co9S8, iron sulfide, etc.). This process also enables more uniform dispersion of the active components and increases the number of stacked layers (i.e., the number of stacked layers of the active phase), thereby improving the catalytic activity of the prepared plastic liquefaction catalyst and enhancing its stability and other properties.

[0056] In practice, the catalyst precursor can be pulverized to 50-150 mesh, such as 50 mesh, 70 mesh, 90 mesh, 100 mesh, 120 mesh, 150 mesh or any combination thereof, and then subjected to sulfidation treatment, which helps to convert more of the metal components into the sulfidated state, thereby further improving the catalytic activity of the plastic liquefaction catalyst for plastic cracking.

[0057] Specifically, the catalyst precursor is brought into contact with a sulfur source for sulfidation treatment. The sulfur source includes, for example, sulfur and / or dimethyl disulfide, and the mass ratio of the sulfur source to the catalyst precursor can be 1:(15-75).

[0058] The mass ratio of sulfur to catalyst precursor can be 1:(10-50), for example, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50 or any combination thereof; the mass ratio of dimethyl disulfide to catalyst precursor can be 1:(5-25), for example, 1:5, 1:8, 1:10, 1:12.5, 1:15, 1:18, 1:20, 1:22, 1:25 or any combination thereof.

[0059] Furthermore, the sulfidation treatment can be carried out in the presence of ethanolamine and distillate oil with a distillation range of 180–290 °C. The mass ratio of ethanolamine to catalyst precursor can be (1–3):100, for example, 1:100, 1.5:100, 2:100, 2.5:100, 3:100 or any combination thereof. The mass ratio of distillate oil to catalyst precursor can be (2–4):1, for example, 2:1, 2.5:1, 3:1, 3.5:1, 4:1 or any combination thereof.

[0060] Generally, the vulcanization process is carried out in an inert atmosphere, which is an inert gas atmosphere, such as nitrogen.

[0061] Furthermore, the reaction pressure of the vulcanization process can be 0.1 to 0.3 MPa, for example, the range of 0.1, 0.15, 0.2, 0.25, 0.3, or any two of them; the vulcanization temperature can be 200 to 250°C, for example, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, or any two of them; and the vulcanization time can be 3 to 5 hours, for example, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, or any two of them.

[0062] Furthermore, the vulcanization treatment can be carried out under stirring conditions, with a stirring rate of 100–300 r / min, for example, 100 r / min, 120 r / min, 150 r / min, 180 r / min, 200 r / min, 230 r / min, 250 r / min, 280 r / min, 300 r / min, or any combination thereof.

[0063] In some embodiments, the vulcanization process includes: mixing the catalyst precursor with sulfur, dimethyl disulfide, ethanolamine, and distillate oil with a distillation range of 180–290°C, and reacting the mixture under stirring conditions of 100–300 r / min at 0.1–0.3 MPa (reaction pressure) and 200–250°C (vulcanization temperature) for 3–5 h (vulcanization time) to obtain a plastic liquefaction catalyst.

[0064] In practice, sulfur, dimethyl disulfide, ethanolamine, and distillate oil with a distillation range of 180-290°C can be added to a reaction vessel containing catalyst precursors. The mixture is then stirred and heated until it reaches the sulfidation treatment temperature. The temperature is then kept constant for a preset time (i.e., the sulfidation treatment time) to complete the sulfidation treatment.

[0065] Generally, after the vulcanization treatment, a product of 50-150 mesh can be produced, which is the plastic liquefaction catalyst. The mesh size is, for example, 50 mesh, 70 mesh, 90 mesh, 100 mesh, 120 mesh, 150 mesh or any combination thereof. The obtained plastic liquefaction catalyst has characteristics such as high specific surface area, which is beneficial to the contact between the plastic liquefaction catalyst and the plastic during the plastic pyrolysis process, increases the degree of interaction between the two, and further improves the plastic pyrolysis efficiency.

[0066] Specifically, a product of 50-150 mesh can be formed by spray drying, or, after the vulcanization treatment, a second solid-liquid separation is performed, and the obtained second solid product is dried and pulverized to 50-150 mesh to obtain a plastic liquefaction catalyst.

[0067] Specifically, the second solid-liquid separation can be carried out at 50–60°C. For example, in some specific embodiments, the second solid-liquid separation process may include: after the sulfidation treatment, the system is allowed to stand at 50–60°C for 8–15 hours, and then the second solid product is separated. The standing temperature is, for example, a range of 50°C, 52°C, 55°C, 58°C, 60°C, or any combination thereof, and the standing time is, for example, a range of 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, or any combination thereof.

[0068] In addition, the second solid-liquid separation can be carried out under normal pressure. In some specific embodiments, after the vulcanization treatment is completed, the temperature is lowered to 50-60°C and the pressure is released to normal pressure. After standing for 8-15 hours, the second solid product is separated.

[0069] Furthermore, the drying conditions for the second solid product can be: a drying temperature of 100–180°C, for example, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C or any combination thereof, and a drying time of 4–6 h, for example, 4 h, 4.5 h, 5 h, 5.5 h, 6 h or any combination thereof.

[0070] The present invention can be performed using conventional methods in the art, such as mechanical crushing; the heating can be performed at a heating rate of 15 to 25°C / h, for example, a range of 15°C / h, 18°C / h, 20°C / h, 22°C / h, 25°C / h or any combination thereof.

[0071] Specifically, the aforementioned spent hydrotreating catalyst is a deactivated hydrotreating catalyst produced from the oil hydrotreating process. In the oil hydrotreating process, the oil is hydrotreated under the action of a hydrotreating catalyst. The hydrotreating catalyst generally includes an alumina support and a metal active component supported on the alumina support. The metal active component can include one or more metals from Group VIB and Group VIII of the periodic table, such as Fe, Mo, W, Co, and Ni. After hydrotreating, the aforementioned hydrotreating catalyst becomes deactivated due to carbon deposits, impurities (such as calcium and magnesium), etc., thus forming spent hydrotreating catalyst.

[0072] For example, the hydrotreating catalyst used in the above-mentioned oil hydrotreating process includes, for instance, a hydrodesulfurization catalyst, and correspondingly, the resulting waste hydrotreating catalyst is a waste hydrodesulfurization catalyst. The above-mentioned oil products include, for instance, diesel oil, but are not limited thereto.

[0073] In some embodiments, the aforementioned waste hydrogenation catalyst may include a first alumina support, and a first metal component, a first carbon component, and a first sulfur component supported on the first alumina support. The first metal component may include one or more metals from Group VIB and Group VIII of the periodic table, such as Fe, Mo, W, Co, Ni, etc.

[0074] The plastic liquefaction catalyst provided in this embodiment of the invention is prepared according to the above-described waste hydrogenation catalyst treatment method. It generally includes a second alumina support, and a second metal component, a second carbon component, a second sulfur component, and a silicon component supported on the second alumina support. The second metal component may include one or more metals from Group VIB and Group VIII of the periodic table, such as Fe, Mo, W, Co, Ni, etc. The sulfur mass content in the plastic liquefaction catalyst may be greater than 8%.

[0075] Specifically, the aforementioned plastic liquefaction catalyst includes an active phase, such as one or more of MoS2, WS2, NiS3, Co9S8, iron sulfide, and iron carbide, which can be used to catalyze the thermal liquefaction (pyrolysis or cracking) of plastics.

[0076] The aforementioned plastic liquefaction catalyst can be in the range of 50 to 150 mesh, for example, 50 mesh, 70 mesh, 90 mesh, 100 mesh, 120 mesh, 150 mesh, or any combination thereof.

[0077] The plastic pyrolysis method provided in this invention includes: pyrolyzing the plastic under the action of the aforementioned plastic liquefaction catalyst, which can improve the plastic pyrolysis efficiency, reduce the pyrolysis temperature, reduce energy consumption, shorten the pyrolysis time, and increase the liquid yield (the liquid yield can reach more than 80%), especially increasing the yield of low-range liquid products (i.e., low-range fractions) (the mass proportion of fractions with a distillation range of less than 350°C in the liquid products generated by pyrolysis can be as high as more than 80%), and can reduce the residue rate, i.e., reduce the solid product yield (less than 5%).

[0078] For example, the above-mentioned pyrolysis process may include: subjecting the plastic to hydrothermal treatment under sub-supercritical conditions in the presence of a plastic liquefaction catalyst, that is, the above-mentioned plastic liquefaction catalyst can be applied to the hydrothermal treatment (hydrothermal liquefaction) process of plastic under sub-supercritical conditions.

[0079] Specifically, plastic, plastic liquefaction catalyst and water can be mixed to form a mixture, and then the above-mentioned pyrolysis can be carried out; wherein, the mass ratio of water to plastic can be (8 to 15):1, such as 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1 or any combination thereof.

[0080] In some specific embodiments, the above-mentioned pyrolysis conditions can be: a reaction pressure of 3 to 6 MPa, for example, a range of 3 MPa, 3.5 MPa, 4 MPa, 4.5 MPa, 5 MPa, 5.5 MPa, 6 MPa or any two thereof; a reaction temperature of 250 to 350°C, for example, a range of 250°C, 280°C, 300°C, 320°C, 350°C or any two thereof; and a reaction time of 80 to 120 min, for example, a range of 80 min, 85 min, 90 min, 95 min, 100 min, 120 min or any two thereof.

[0081] In addition, during the above-mentioned pyrolysis process, the mass ratio of plastic liquefaction catalyst to plastic can be 0.1:(0.8 to 1.2), for example, 0.1:0.8, 0.1:0.9, 0.1:1, 0.1:1.1, 0.1:1.2 or any combination thereof.

[0082] Furthermore, the above-mentioned pyrolysis process can be carried out under stirring conditions, with a stirring rate of, for example, 150 to 250 rpm, such as 150 rpm, 180 rpm, 200 rpm, 220 rpm, 250 rpm, or any combination thereof.

[0083] Specifically, the aforementioned plastics can be waste plastics (plastics in solid waste), such as mixed waste plastics from waste (such as household waste, rotten waste) or other mixed waste plastics that cannot be sorted and reused. In practice, these wastes can be screened to remove impurities such as bricks, mud, and metals, and then the waste plastics can be screened out. The waste plastics can then undergo the aforementioned pyrolysis process. Through the aforementioned pyrolysis process, the waste plastics can be converted into liquid hydrocarbons, which can be used as fuels or industrial raw materials and other high-value products, thus realizing the high-value conversion of waste plastics.

[0084] In some embodiments, the plastics described above may include hydrocarbon plastics, such as one or more of polyethylene, polyvinyl chloride, polypropylene, ethylene-propylene copolymer, ethylene-octene copolymer, ethylene-butene copolymer, ethylene-cycloolefin copolymer, polydicyclopentadiene, cyclopentadiene copolymer, and polystyrene.

[0085] The present invention will be further described below through specific embodiments and comparative examples. In the following embodiments, waste hydrogenation catalyst A is industrial waste diesel hydrogenation catalyst (i.e., waste hydrogenation catalyst generated during the diesel hydrogenation process), and its main components are as follows: the sum of the mass contents of nickel and tungsten is 21.5%, the mass content of carbon is 12.2%, the mass content of sulfur is 8.6%, the mass content of alumina is 45.3%, and the balance is other substances; waste hydrogenation catalyst A is mechanically pulverized to 50-150 mesh and is recorded as sample A-1; the main components of waste hydrogenation catalyst B are as follows: the sum of the mass contents of cobalt, nickel, and molybdenum is 15.8%, the mass content of carbon is 9.5%, the mass content of sulfur is 6.4%, the mass content of alumina is 55.3%, and the balance is other substances; waste hydrogenation catalyst B is mechanically pulverized to 50-150 mesh and is recorded as sample B-1. In the following embodiments, the silica sol used is silica sol with a mass content of 40% silica.

[0086] Example 1

[0087] Mix 100g of sample A-1, 300g of deionized water, and 5.0g of silica sol. Start stirring at a rate of 150r / min and heat to 180℃ at a rate of 20℃ / h. Hold the temperature for 15h. After the temperature is held, cool down to 90℃, add 10.0g of glucose and 8.0g of ferric nitrate, stir at a rate of 80r / min, and hold the temperature for 5h. After the temperature is held, cool down to 50℃, stop stirring, and let stand for 8h. Separate the solid and liquid components. Dry the first solid product at 150℃ for 5.0h, then calcine at 500℃ for 4h. Mechanically pulverize the obtained catalyst precursor to 50-150 mesh to obtain the pulverized catalyst precursor.

[0088] 100g of pulverized catalyst precursor, 4.0g of sulfur, 8.0g of dimethyl disulfide, 2.0g of ethanolamine, and 300g of distillate oil with a distillation range of 180-290℃ were added to a reactor. The air in the reactor was replaced with nitrogen to create an inert atmosphere. The reaction pressure was 0.2MPa. Stirring was started and the temperature was increased at a stirring rate of 150r / min and a heating rate of 20℃ / h to 230℃. The temperature was held for 4h. After the temperature was held, the temperature was lowered to 50℃, stirring was stopped, the pressure was released to atmospheric pressure, and the mixture was allowed to stand for 12h. The solid and liquid were then separated. The resulting second solid product was dried at 150℃ for 5h and then pulverized to 50-150 mesh to obtain the plastic liquefaction catalyst, denoted as Cat-1.

[0089] Example 2

[0090] Mix 100g of sample A-1, 200g of deionized water, and 6.0g of silica sol. Start stirring at 100r / min and heat to 180℃ at a rate of 20℃ / h. Hold the temperature for 10h. After holding the temperature, cool down to 80℃, add 5.0g of glucose and 5.0g of ferric nitrate, stir at 50r / min, and hold the temperature for 4h. After holding the temperature, cool down to 60℃, stop stirring, and let stand for 5h. Separate the solid and liquid phases. Dry the first solid product at 150℃ for 5h, then calcine at 450℃ for 3h. Mechanically pulverize the obtained catalyst precursor to 50-150 mesh to obtain the pulverized catalyst precursor.

[0091] 100g of pulverized catalyst precursor, 2.0g of sulfur, 4.0g of dimethyl disulfide, 1.0g of ethanolamine, and 200g of distillate oil with a distillation range of 180-290℃ were added to a reactor. The reactor was purged with nitrogen to create an inert atmosphere. The reaction pressure was 0.1MPa. Stirring was started and the temperature was increased at a stirring rate of 150r / min and a heating rate of 20℃ / h until the temperature reached 200℃. The temperature was then maintained for 3h. After the temperature was maintained, the temperature was lowered to 60℃, stirring was stopped, and the pressure was released to atmospheric pressure. After standing for 12h, the solid and liquid were separated. The resulting second solid product was dried at 150℃ for 4h and then pulverized to 50-150 mesh to obtain the plastic liquefaction catalyst, denoted as Cat-2.

[0092] Example 3

[0093] Mix 100g of sample A-1, 500g of deionized water, and 10.0g of silica sol. Start stirring at a rate of 300r / min and a heating rate of 20℃ / h. Heat to 180℃ and hold at that temperature for 20h. After holding at that temperature, cool down to 100℃, add 8.0g of glucose and 10.0g of ferric nitrate, stir at 100r / min, and hold at that temperature for 6h. After holding at that temperature, cool down to 60℃, stop stirring, and let stand for 10.0h. Separate the solid and liquid phases. Dry the first solid product at 150℃ for 5h, then calcine at 550℃ for 5h. Mechanically pulverize the obtained catalyst precursor to 50-150 mesh to obtain the pulverized catalyst precursor.

[0094] 100g of pulverized catalyst precursor, 10.0g of sulfur, 20.0g of dimethyl disulfide, 3.0g of ethanolamine, and 400g of distillate oil with a distillation range of 180-290℃ were added to a reactor. The air in the reactor was replaced with nitrogen to create an inert atmosphere. The reaction pressure was 0.3MPa. Stirring was started and the temperature was increased at a stirring rate of 150r / min and a heating rate of 20℃ / h until the temperature reached 250℃. The temperature was then maintained for 5h. After the temperature was maintained, the temperature was lowered to 60℃, stirring was stopped, and the pressure was released to atmospheric pressure. After standing for 12h, solid-liquid separation was performed. The obtained second solid product was dried at 150℃ for 6h and then pulverized to 50-150 mesh to obtain the plastic liquefaction catalyst, denoted as Cat-3.

[0095] Example 4 (the obtained plastic liquefaction catalyst is designated as Cat-4): The difference from Example 1 is that sample B-1 is used instead of sample A-1, and the other conditions are the same as in Example 1.

[0096] Example 5 (the obtained plastic liquefaction catalyst is designated Cat-5): The difference from Example 2 is that sample B-1 is used instead of sample A-1, and the other conditions are the same as in Example 2.

[0097] Example 6 (the prepared plastic liquefaction catalyst is designated Cat-6): The difference from Example 3 is that sample B-1 is used instead of sample A-1, and the other conditions are the same as in Example 3.

[0098] Testing revealed that the active components in Cat-1 through Cat-6 were uniformly dispersed, with a high number of active phase layers. Taking Cat-1 as an example, its scanning electron microscope (SEM) image is shown below. Figure 1Cat-1 contains various types of active phases, each with different sizes and stacking numbers, characteristics that facilitate the hydrothermal liquefaction reaction of plastics. Furthermore, high-frequency infrared carbon-sulfur analysis of Cat-1 to Cat-6 showed that the sulfur content in these plastic liquefaction catalysts was greater than 8 wt%, with most of the active metals converted to sulfide states. Taking Cat-1 as an example, X-ray diffraction (XRD) analysis was performed on Cat-1 and A-1 samples, and the results are shown below. Figure 2 As can be seen from the XRD pattern, Cat-1 exhibits characteristic peaks of the sulfurized state and silicon, making it suitable for hydrothermal liquefaction reactions of plastics. The relevant test results for Cat-2 to Cat-6 are similar to those for Cat-1, and will not be repeated here.

[0099] The following plastic pyrolysis experiments were conducted using Cat-1 to Cat-2, as well as samples A-1 and B-1, as catalysts to verify the catalyst performance.

[0100] Waste such as household waste and stale waste is screened to remove large bricks, mud, metal and other impurities in order to screen out plastics, and then the plastics are crushed and granulated to 2-3mm.

[0101] Water, plastic, and catalyst were mixed and subjected to a pyrolysis reaction at 4.5 MPa, 300 °C, and 200 rpm for 100 min. The mass ratio of water to plastic was 10:1, and the mass ratio of catalyst to plastic was 0.1:1.

[0102] After the pyrolysis reaction is completed, the resulting solid-liquid mixture is condensed after venting and degassing, and then the solid and liquid products are separated to obtain solid products and liquid products.

[0103] The liquid yield (liquid yield) and residue rate were calculated using the following formulas, and the results are shown in Table 1:

[0104] Liquid product yield = (mass of liquid product ÷ mass of plastic) × 100%

[0105] Residue rate = ((mass of solid product - mass of catalyst) ÷ mass of plastic) × 100%

[0106] Table 1

[0107] catalyst Liquid substance yield, % Residue rate, % Cat-1 89.5 2.3 Cat-2 83.2 4.8 Cat-3 84.8 3.9 Cat-4 91.4 0.8 Cat-5 85.7 2.4 Cat-6 86.4 3.1 A-1 72.3 15.1 A-2 70.8 17.9

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for treating waste hydrogenation catalyst, characterized in that, include: S1. A first mixed system containing waste hydrogenation catalyst, water, and silicon source is subjected to a first reaction at 150~200°C; the waste hydrogenation catalyst includes an alumina support, and metal components, carbon components, and sulfur components supported on the alumina support. S2. Then cool down to 80~100℃, add glucose and iron source, and maintain 80~100℃ to carry out the second reaction; S3. Then, the first solid-liquid separation is performed, and the obtained first solid product is calcined to obtain the catalyst precursor. S4. The catalyst precursor is subjected to sulfidation treatment to obtain a plastic liquefaction catalyst.

2. The method for treating spent hydrogenation catalyst according to claim 1, characterized in that, In the first mixed system, the mass of the water is 2 to 5 times the mass of the spent hydrogenation catalyst; and / or, the mass ratio of the silicon source to the spent hydrogenation catalyst is 1:(10 to 20); and / or, the silicon source includes silica sol. And / or, the process of the first reaction includes: mixing the waste hydrogenation catalyst, water, and silicon source to form the first mixed system, starting the stirring, heating to 150-200℃ under the stirring state of 100-300r / min, and holding the temperature for 10-20h.

3. The method for treating spent hydrogenation catalyst according to claim 1, characterized in that, The mass ratio of glucose to the spent hydrogenation catalyst is 1:(10~20); and / or, the mass ratio of iron source to the spent hydrogenation catalyst is 1:(10~20); and / or, the iron source includes a soluble iron salt, which includes ferric nitrate. And / or, the second reaction process includes: maintaining a constant temperature of 80-100℃ for 4-6 hours under stirring conditions at a stirring rate of 50-100 r / min.

4. The method for treating spent hydrogenation catalyst according to claim 1, characterized in that, The first solid-liquid separation process includes: allowing the system after the second reaction to stand at 50-60°C for 5-10 hours to separate the first solid product therein; And / or, the first solid product is dried at 100~180℃ for 4~6h before being calcined; And / or, the calcination conditions are: calcination temperature of 450~550℃ and calcination time of 3~5h.

5. The method for treating spent hydrogenation catalyst according to claim 1, characterized in that, The catalyst precursor is pulverized to 50-150 mesh and then subjected to the sulfidation treatment. And / or, the vulcanization process includes: mixing the catalyst precursor with sulfur, dimethyl disulfide, ethanolamine, and distillate oil with a distillation range of 180~290℃, and reacting it at 0.1~0.3MPa and 200~250℃ for 3~5 hours under stirring at a stirring rate of 100~300r / min to obtain the plastic liquefaction catalyst.

6. The method for treating spent hydrogenation catalyst according to claim 5, characterized in that, The mass ratio of sulfur to catalyst precursor is 1:(10~50), the mass ratio of dimethyl disulfide to catalyst precursor is 1:(5~25), the mass ratio of ethanolamine to catalyst precursor is (1~3):100, and the mass ratio of distillate oil to catalyst precursor is (2~4):

1.

7. The method for treating spent hydrogenation catalyst according to claim 1, characterized in that, After the vulcanization treatment is completed, a 50-150 mesh product is formed by spray drying to obtain the plastic liquefaction catalyst. Alternatively, after the vulcanization treatment is completed, solid-liquid separation is performed, and the resulting second solid product is dried and pulverized to 50-150 mesh to obtain the plastic liquefaction catalyst.

8. A plastic liquefaction catalyst, characterized in that, It is prepared according to the waste hydrogenation catalyst treatment method according to any one of claims 1-7.

9. A method for pyrolyzing plastics, characterized in that, This includes causing the plastic to crack under the action of the plastic liquefaction catalyst as described in claim 8.

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