A reforming hydrotreating catalyst for generating oil and a method for preparing the same

Abstract

The application discloses a reforming oil hydrogenation catalyst and a preparation method thereof. The catalyst comprises a carrier and an active component. The carrier is alumina, and the alumina has a leaf-shaped aggregate structure. The active component comprises palladium and platinum. The content of the active component palladium is 0.05-0.50 wt% in terms of metal, and the content of the active component platinum is 0.05-0.50% in terms of metal. The catalyst carrier has a leaf-shaped aggregate structure, high crystallinity, good thermal stability and concentrated pore size distribution, can provide a larger specific surface area for the dispersion of the active component, and has a larger pore size, so that the mass transfer and diffusion of reaction molecules and product molecules can be strengthened, and the hydrogenation activity, selectivity and stability of the catalyst are improved.

Description

Technical Field

[0001] This invention relates to a catalyst for hydrogenation of reforming oil and its preparation method, specifically to a catalyst for selective hydrogenation of reforming oil to remove olefins and its preparation method. Background Technology

[0002] Aromatics (benzene, toluene, xylene (BTX)) are important organic chemical raw materials, second only to ethylene and propylene in terms of production volume and scale. Aromatics extraction using reformate as feedstock is one of the main processes in BTX production. However, in addition to being rich in aromatics, reformate and cracked gasoline also contain impurities such as olefins. To produce qualified aromatics, the reformate must be deolefinized. Currently, most plants use the clay refining process for deolefin removal, which utilizes the acidic centers of clay to cause olefins to undergo reactions such as alkylation and polymerization. However, this process has a short service life, requires large quantities of small-particle clay, and easily causes large system pressure drops, necessitating premature replacement. Furthermore, once deactivated, the clay cannot be regenerated, requiring replacement every few months or even weeks. The increased replacement frequency exacerbates aromatics loss and workload, and large amounts of waste clay (hazardous waste) need to be landfilled or coked, causing not only environmental pollution but also incurring additional high landfill or coking costs, placing increasing environmental pressure on enterprises.

[0003] Chinese Patent 201310345116.4 provides a method for selective hydrogenation of reformed oil, using a catalyst containing 0.3% palladium by weight in Pd / γ-Al2O3. However, the hydrogenation stability of single-metal palladium catalysts is poor, and heat-sensitive substances such as heavy components in the oil are prone to polymerization and strong adsorption on the catalyst surface, causing the catalyst to deactivate quickly.

[0004] Chinese patent CN110961124A discloses a catalyst for the hydrodeolefins treatment of reformed oil, comprising a sulfate-containing alumina support and active components with the following contents calculated based on alumina: Pd 0.22–0.40 wt%, Pt 0.07–0.18 wt%, chlorine 0.4–3.0 wt%, wherein the sulfate content in the sulfate-containing alumina support is 0.3–3.0 wt% based on alumina. This catalyst can effectively remove olefins from reformed oil with a bromine index higher than 4000 mgBr / 100g oil. Pre-sulfurization of the catalyst is not required before use, and a deolefins-treated product with a bromine index less than 50 mgBr / 100g oil can be obtained, with aromatic hydrocarbon loss less than 0.5 wt%. The support used in this patent contains sulfate impurities. Although it can provide sulfur precursors, sulfate not only affects the crystallinity of alumina, but the sulfate in the support is also difficult to reduce. The high reduction temperature inevitably leads to the growth of palladium and platinum grains, reducing the dispersion and utilization rate of the active components.

[0005] Chinese patent ZL201610561694.5 discloses a catalyst for the liquid-phase hydrodeolefination of reformed oil and its application. The catalyst uses modified attapulgite clay acidified with inorganic acids as a support and contains 0.1–3.0 wt% of active components and 0.05–2.0 wt% of additives. This catalyst is used for the continuous liquid-phase hydrodeolefination of reformed oil at a reaction temperature of 120–180 °C, a reaction pressure of 1.0–2.0 MPa, and a space velocity of 1–12 h⁻¹. -1 Under hydrogen-to-oil ratios of 6:1 to 16:1, it can effectively remove trace amounts of olefins from reformed oil, with a bromine index of less than 100 mgBr / 100 g oil and aromatic loss of less than 0.5 wt%. This patent uses modified attapulgite clay acidified with inorganic acids as a carrier. The high acidity of the carrier can exacerbate coking reactions and affect long-term operational stability.

[0006] Alumina is a primary support for industrial hydrogenation catalysts and has wide applications in industry. The microstructure and surface properties of alumina significantly influence the performance of supported hydrogenation catalysts; therefore, the controllable synthesis of alumina morphology has attracted considerable research interest. Currently, researchers have prepared alumina morphologies including flakes, rods, and spherical shapes using various methods. Nanosheet alumina possesses a large specific surface area, high crystallinity, and concentrated pore size distribution, exhibiting high dispersibility of active metals in the catalyst. Furthermore, it demonstrates excellent mass transfer performance, offering superior advantages over traditional alumina in improving catalyst activity, selectivity, and resistance to coking.

[0007] Currently, the synthesis of sheet-like alumina mainly focuses on micron-sized sheet-like alumina, primarily used for preparing sheet-like alumina ceramics. The synthesis routes for nano-sheet-like alumina are mostly developed based on surfactants as templates, which are costly and prone to agglomeration during high-temperature calcination, thus limiting their industrialization.

[0008] Chinese patent CN201710944136.1 discloses a method for preparing a nano-alumina carrier with a surface rich in defect sites: the steps are as follows: (1) Inorganic aluminum salt and precipitant are dissolved in a water-ethylene glycol mixed solvent at a molar ratio of 1:5 to 1:9, and stirred to obtain a transparent solution. The solution is then transferred to a hydrothermal reactor. The hydrothermal reaction temperature is 100 to 200°C, and the reaction time is 12 to 48 hours. (2) After the reaction is completed, the reaction material is filtered, washed, dried, and calcined to obtain a nano-alumina carrier rich in surface defects with a specific surface area of ​​150 to 400 m². 2 / g, pore volume is 0.34~0.62cm³ 3 / g. However, ethylene glycol in the mixed solvent is easily oxidized by hydrothermal metabolism to produce toxic oxalic acid, thus it cannot be widely used as a solvent and is not conducive to promotion.

[0009] Chinese patent CN201210427889.2 discloses a method for preparing an alumina carrier, comprising the following steps: taking an appropriate amount of aluminum salt solution with a concentration of 0.5-2.5 mol / L, adding an appropriate amount of urea to the aluminum salt solution and stirring until completely dissolved, wherein the amount of urea added is equal to the ratio of urea to Al. 3+ The molar ratio is 2-10:1. The above solution is placed in a sealed reaction vessel and reacted at 140℃-200℃ for 2-12 hours, followed by direct calcination to prepare the alumina support. Although the support prepared by this method has a high specific surface area and large pore size, the method does not filter or wash the material after the reaction; instead, it directly dries and calcines it to obtain the alumina support. This results in a high content of amorphous alumina and a dispersed pore distribution in the obtained alumina support, limiting its further application.

[0010] Chinese patent CN201110351132.5 provides an improved hydrothermal method for preparing porous alumina ultrafine powder. The method uses aluminum inorganic salt as raw material and urea as co-precipitant to generate a precursor under hydrothermal conditions. The precursor is then centrifuged, washed, dried, and calcined to obtain porous alumina ultrafine powder with high purity, narrow particle size distribution, and high porosity.

[0011] Chinese patent CN107540007A discloses a method for preparing nanosheet mesoporous alumina: using inorganic aluminum salt as the aluminum source, triethanolamine as an additive, and ethylenediamine as a precipitant, nanosheet mesoporous alumina is obtained by hydrothermal aging treatment. The thickness of the nanosheet alumina sheets is 1-10 nm and the width is 0.1-0.5 μm.

[0012] Chinese patent CN107777713A discloses a γ-alumina hexagonal nanosheet material and its preparation method, with a size of 50-500 nm and a thickness of 5-10 nm. This invention uses aluminum alkoxides as raw materials, controls the two-dimensional growth of its intermediate alumina hydroxide through organic amines, and prepares γ-alumina hexagonal nanosheets using chemical precipitation and hydrothermal methods.

[0013] Chinese patent CN104961146A discloses a nanosheet aluminum hydroxide colloid and its preparation method, which involves directly hydrothermating anhydrous ethanol and anhydrous aluminum chloride at 220-300℃ to obtain a nanosheet gel with a thickness of 3-20 nm.

[0014] Chinese patent CN106276992A discloses a method for preparing leaf-shaped nano-γ-alumina. The method involves dissolving inorganic aluminum salts and urea in water to obtain a transparent solution, transferring the solution to a high-pressure reactor, and then introducing hydrogen gas into the reactor to maintain a certain pressure and temperature for the reaction to obtain leaf-shaped nano-γ-alumina. However, the leaf-shaped nano-γ-alumina is in a dispersed state and does not accumulate. It is prone to agglomeration during high-temperature calcination. When used as a catalyst support to load active metals, it reduces the dispersion of the active metals on the support surface. Furthermore, the use of hazardous hydrogen gas during the preparation process is detrimental to production safety.

[0015] The article by Li Jinlin et al., “Controllable Synthesis and Characterization of γ-Al2O3 Nanocrystals with Specific Morphology, Journal of South-Central University for Nationalities (Natural Science Edition), 2016, 35: 1-4,” prepared alumina nanosheets with a length of 60-100 nm using acetic acid and isopropanol as raw materials and hydrothermally at 200℃. The main exposed crystal plane was the (110) crystal plane. The article by Yuguo Xia et al., “Synthesis of AlOOH nanocrystals with different morphologies due to the effect of sulfate ions and the corresponding formation mechanism study, Phys. Chem. Chem. Phys., 2013, 15, 18290,” used nano-AlOOH as raw material, added sodium sulfate and sulfuric acid, and hydrothermally treated at 200℃ for 24 hours to obtain alumina nanosheets with a size of 60-100 nm. The alumina prepared by this method has a small specific surface area (<100 nm). 2 Moreover, the preparation process uses dilute acid, and the high-temperature hydrothermal process places high demands on the reactor material, which is not conducive to large-scale production.

[0016] Therefore, further research is needed in this field on hydrogenation catalysts for reformed oil and the supports used therein. Summary of the Invention

[0017] The main objective of this invention is to provide a reforming oil hydrogenation catalyst and its preparation method, so as to overcome the defects of existing reforming oil hydrogenation catalysts such as low hydrogenation activity, poor selectivity, and short service life.

[0018] To achieve the above objectives, the present invention provides a reforming oil hydrogenation catalyst, comprising a support and an active component, wherein the support is alumina having a leaf-like aggregate structure, and the active component comprises palladium and platinum; based on the total weight of the catalyst, the active palladium content (calculated as metal) is 0.05–0.50 wt%, and the platinum content (calculated as metal) is 0.05–0.50 wt%.

[0019] In one embodiment, the reforming product hydrotreating catalyst of the present invention further includes cerium and chlorine as additives. Based on the total weight of the catalyst, the content of cerium as a metal is greater than 0 and less than or equal to 2.0 wt%, and the content of chlorine as an element is 0.1 to 2.0 wt%. It also includes alkali metal and / or alkaline earth metal additives. Based on the total weight of the catalyst, the content of alkali metal and / or alkaline earth metal additives as a metal is greater than 0 and less than or equal to 2.0 wt%.

[0020] In one embodiment of the reforming product oil hydrotreating catalyst of the present invention, the catalyst has a specific surface area of ​​150–300 m². 2 / g, pore volume 0.30~0.70ml / g, most probable pore size 5~15nm.

[0021] To achieve the above objectives, the present invention also provides a method for preparing a reforming product oil hydrogenation catalyst, wherein the catalyst comprises a support and an active component, the support being alumina, and the method for preparing the alumina includes:

[0022] Step 1: Add a compound that can decompose into NH3 and CO2 to the inorganic aluminum salt aqueous solution, and stir until completely dissolved to form a mixed solution;

[0023] Step 2: Pass CO2 gas at a pressure of 0.1-2 MPa into a sealed container containing the mixed solution for hydrothermal treatment and calcination to obtain alumina.

[0024] In one embodiment of the method for preparing the reforming product oil hydrogenation catalyst of the present invention, the compound that can decompose into NH3 and CO2 is at least one of the group consisting of ammonium carbonate, ammonium bicarbonate, urea and ammonium oxalate.

[0025] In one embodiment of the method for preparing the reforming oil hydrogenation catalyst of the present invention, the inorganic aluminum salt in the aqueous solution is calculated as aluminum ions, and the molar ratio of the inorganic aluminum salt to the compound that can decompose into NH3 and CO2 is 0.1 to 4.0; the inorganic aluminum salt is at least one of the group consisting of aluminum sulfate, aluminum nitrate and aluminum chloride.

[0026] In one embodiment of the preparation method of the reforming product oil hydrogenation catalyst of the present invention, the hydrothermal treatment temperature is 120-200℃, the hydrothermal treatment time is 4-24h, the calcination temperature is 550-800℃, and the calcination time is 3-8h.

[0027] In one embodiment of the method for preparing the reforming product oil hydrogenation catalyst of the present invention, the method for preparing the catalyst includes: loading a precursor of an active component onto the alumina, wherein the precursor of the active component includes a palladium-soluble compound and a platinum-soluble compound.

[0028] In one embodiment of the method for preparing the reforming product hydrogenation catalyst of the present invention, the method further includes: loading a precursor of an auxiliary agent onto the alumina support, wherein the precursor of the auxiliary agent includes a soluble salt of cerium, a soluble acid or salt containing chlorine, a soluble salt of an alkali metal, or a soluble salt of an alkaline earth metal.

[0029] To achieve the above objectives, the present invention further provides the application of the catalyst obtained by the above preparation method in the hydrogenation of reforming product oil.

[0030] The beneficial effects of this invention are:

[0031] This invention introduces additional CO2 gas during the alumina preparation process, which effectively neutralizes the number of hydroxyl groups on the surface of the alumina flakes during crystallization. On one hand, this reduces flake curling caused by hydroxyl condensation during crystallization and effectively controls the flake width. On the other hand, it reduces the saturation of coordination between hydroxyl groups and aluminum ions, making the plate-like alumina more conducive to chelation coordination with active metals. Furthermore, this invention increases the molar ratio of aluminum ions to compounds that can decompose into NH3 and CO2. A higher molar ratio helps increase the yield per batch, effectively reducing production costs.

[0032] The alumina support used in the catalyst of this invention has a leaf-like aggregate structure, which has the characteristics of regular morphology, uniform particle size, concentrated pore size distribution, high crystallinity and thermal stability. Its leaf-like aggregate structure overcomes the disadvantages of general nano-sheet alumina products, which are difficult to separate and prone to agglomeration at high temperature. The leaf-like aggregate structure of this invention makes alumina separation simple and does not agglomerate during high-temperature calcination, and can continue to maintain the nano-sheet morphology. It is an excellent support for reforming product oil hydrodeolefination catalyst.

[0033] The catalyst support of this invention has a leaf-like aggregate structure with high crystallinity, good thermal stability, and concentrated pore size distribution. This provides a large specific surface area for the dispersion of the active component, and the larger pore size enhances mass transfer and diffusion of reactant and product molecules, thereby improving the catalyst's hydrogenation activity and selectivity. More importantly, a strong interaction occurs between the support and the active component, which not only alters the microscopic electronic structure of the active center but also reduces the acidic centers generated by the synergistic effect between the support and the active component. This effectively inhibits the strong adsorption and deposition of thermosensitive macromolecules on the catalyst surface, thus significantly improving the catalyst's hydrogenation stability. Attached Figure Description

[0034] Figure 1 This is a scanning electron microscope (SEM) image of the alumina support with a leaf-like aggregate structure prepared in Example 1 of the present invention.

[0035] Figure 2 This is a scanning electron microscope (SEM) image of the alumina support prepared in Comparative Example 1 of the present invention. Detailed Implementation

[0036] The following provides a detailed description of the embodiments of the present invention. These embodiments are implemented based on the technical solution of the present invention and provide detailed implementation methods and processes. However, the scope of protection of the present invention is not limited to the following embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions.

[0037] This invention provides a reforming oil hydrogenation catalyst, comprising a support and an active component. The support is alumina having a leaf-like aggregate structure. The active component comprises palladium and platinum. Based on the total weight of the catalyst, the active palladium content (based on metal content) is 0.05–0.50 wt%, and the platinum content (based on metal content) is 0.05–0.50 wt%.

[0038] The catalyst support alumina of this invention has a leaf-like aggregate structure, meaning that the alumina is mainly leaf-shaped, and the leaves aggregate to form clusters, resulting in a more regular microstructure, high crystallinity, and more concentrated pore size distribution. The prepared catalyst exhibits high dispersion of active components, high mass and heat transfer efficiency, and excellent hydrogenation activity and selectivity. Under mild operating conditions, only a small amount of hydrogen needs to be added to hydrogenate olefins in reformate into alkanes. It not only has a high olefin removal rate but also low aromatic loss, and can reduce the production of heavy aromatics from polymerization / condensation, thereby increasing the yield of value-added products. The catalyst can operate continuously and stably in industrial plants for more than 3 years, significantly reducing or even eliminating the use of bleaching clay, thus reducing the environmental burden on enterprises.

[0039] In one embodiment, based on the total weight of the catalyst (100%), the palladium content (metal content) is 0.1–0.3 wt%, the platinum content (metal content) is 0.05–0.2 wt%, the chlorine content is 0.5–1.2 wt%, the cerium content is 0.1–1.0 wt%, and the alkali metal and / or alkaline earth metal content is 0.3–1.0 wt%. The active components and additives of this invention are supported on a support and highly dispersed on the support. In one embodiment, the specific surface area of ​​the catalyst of this invention is 150–300 m². 2 / g, with a pore volume of 0.30–0.70 ml / g and a most probable pore size of 5–15 nm. In another embodiment, the catalyst of the present invention has a specific surface area of ​​170–250 m² / g. 2 / g, pore volume is 0.45~0.70ml / g, and most probable pore size is 5~10nm.

[0040] In one embodiment, the present invention also provides a method for preparing the above-mentioned alumina support, comprising:

[0041] Step 1: Add a compound that can decompose into NH3 and CO2 to the inorganic aluminum salt aqueous solution, and stir until completely dissolved to form a mixed solution;

[0042] Step 2: Pass CO2 gas at a pressure of 0.1-2 MPa into a sealed container containing the mixed solution for hydrothermal treatment and calcination to obtain alumina.

[0043] In this invention, CO2 gas is introduced additionally during the alumina preparation process, which can effectively neutralize the number of hydroxyl groups on the surface of alumina leaves during the crystallization process. On the one hand, it reduces the leaf curling phenomenon caused by hydroxyl condensation during the crystallization process and can effectively control the width of alumina leaves, thereby achieving the purpose of controlling the morphology of alumina. On the other hand, it can reduce the saturation of coordination between hydroxyl groups and aluminum ions, making the plate-like alumina more conducive to chelation coordination with active metals.

[0044] In one embodiment, the compound of the present invention that can decompose into NH3 and CO2 refers to the compound that can decompose into NH3 and CO2 under the hydrothermal treatment conditions in step 2; in another embodiment, the compound of the present invention that can decompose into NH3 and CO2 can be one or more of ammonium carbonate, ammonium bicarbonate, urea and ammonium oxalate.

[0045] The inorganic aluminum salt aqueous solution of the present invention refers to a solution formed by dissolving inorganic aluminum salt in water. In one embodiment, the inorganic aluminum salt is a soluble aluminum-containing inorganic salt, and further, it can be one or more of aluminum sulfate, aluminum nitrate and aluminum chloride.

[0046] In one embodiment, the inorganic aluminum salt, calculated as aluminum ions, has a molar ratio of 0.1 to 4.0, preferably 0.5 to 3, to the inorganic aluminum salt of the present invention and the compound capable of decomposing into NH3 and CO2.

[0047] In this invention, step 2, the hydrothermal treatment, is carried out in a closed container, such as a hydrothermal reactor or an autoclave. Step 1, the dissolution step, can be carried out directly in a closed container, or the mixed solution from step 1 can be obtained and then introduced into a closed container; this invention is not limited thereto.

[0048] After introducing CO2 gas at a pressure of 0.1–2 MPa into a sealed container containing the mixed solution, the CO2 gas supply is cut off, keeping the container sealed, and hydrothermal treatment begins. The pressure during the hydrothermal treatment process includes the pressure generated by the decomposition of compounds that can decompose into NH3 and CO2, the pressure generated during the reaction of inorganic aluminum salts with compounds that can decompose into NH3 and CO2, and the pressure of the additionally introduced CO2 gas. The hydrothermal treatment temperature is 120–200°C, and the hydrothermal treatment time is 4–24 hours. In one embodiment, introducing CO2 gas at a pressure of 0.1–2 MPa into the sealed container means introducing CO2 gas into the sealed container to raise the pressure inside the sealed container to 0.1–2 MPa.

[0049] The product obtained after hydrothermal treatment undergoes solid-liquid separation. The resulting solid is washed, dried, shaped, and calcined to obtain alumina with a leaf-like aggregate structure. This invention does not impose particular limitations on the solid-liquid separation method, such as filtration. The drying temperature is, for example, 80–120°C, and the drying time is 3–8 hours.

[0050] Before molding, one or two of the following can be added to the leaf-shaped aggregate structure alumina of the present invention: a binder and an extrusion aid. The specific substances used and the amounts added can be determined according to existing knowledge in the art. For example, the binder can be one or more of nitric acid, phosphoric acid, hydrochloric acid, and sulfuric acid, and the amount added is 3-5% of the total weight of the sample to be molded; the extrusion aid can be guar gum powder, etc., and its amount is generally 2-6% of the total weight of the sample to be molded.

[0051] The calcination method and conditions are commonly used for catalyst support calcination. Vertical furnaces, converters, and mesh belt kilns can be used. The calcination conditions for the support can be: calcination temperature of, for example, 550–800℃, and calcination time of 3–8 hours. Preferably, the calcination temperature is 620–750℃, and the calcination time is 4–6 hours.

[0052] This invention does not impose particular limitations on the preparation method of the above-mentioned reforming oil hydrogenation catalyst. For example, an impregnation method can be used to load the precursor of the active component onto the alumina. The precursor of the active component is, for example, a palladium-soluble compound and a platinum-soluble compound. Herein, a palladium-soluble compound refers to a compound containing palladium and soluble in water, and a platinum-soluble compound refers to a compound containing platinum and soluble in water.

[0053] In one embodiment, the palladium-soluble compound is, for example, palladium chloride, palladium nitrate, palladium acetate, sodium tetrachloropalladium, or dichlorotetraamminepalladium; the platinum-soluble compound is, for example, chloroplatinic acid, dichlorotetraammineplatinum, ammonium chloroplatinate, platinum trichloride, or platinum tetrachloride. Palladium is preferably added in the form of palladium chloride, and platinum is preferably added in the form of chloroplatinic acid. This invention does not specify a detailed method for loading the catalyst active component; for example, a supersaturated impregnation method can be used, in which an aqueous solution containing palladium and platinum-soluble compounds is impregnated onto a support, dried at 80–150°C for 3–8 hours, and then calcined at 300–500°C for 3–8 hours.

[0054] The catalyst of this invention contains chlorine as an auxiliary agent, with a content of 0.1–2.0 wt%, preferably 0.5–1.2 wt% (based on the total weight of the catalyst). Its function is to improve the dispersion of the active metals palladium and platinum, ensuring a uniform radial distribution of the active components on the support. In this invention, chlorine is preferably added simultaneously with the active components palladium and platinum in the form of hydrochloric acid or trichloroacetic acid.

[0055] The catalyst of this invention contains the rare earth element cerium (in oxide form), with a metal content greater than 0 and less than or equal to 2.0 wt%, preferably 0.1 to 1.0 wt%. The addition of cerium as an additive can inhibit the growth of active component grains during high-temperature calcination, improve the dispersion of the active component, and enhance the hydrogenation activity, selectivity, and stability of the catalyst. In this invention, cerium is preferably added in the form of a soluble nitrate. The catalyst of this invention also contains alkali metals and / or alkaline earth metals (in oxide form), with a metal content greater than 0 and less than or equal to 2.0 wt%, preferably 0.3 to 1.0 wt%. The alkali metals and / or alkaline earth metals are one or more of Li, Na, K, Ca, Mg, Sr, and Be, preferably one or two of Li and K. When a catalyst is used for the hydrogenation of reformed oil, the olefins in the oil are prone to polymerization and gum formation. Adding alkali metals and / or alkaline earth metals as promoters can inhibit the acidity of the catalyst support surface. Adjusting the surface acidity / alkalinity of the catalyst can improve hydrogenation activity and stability, which helps reduce gum formation during hydrogenation and thus extends the catalyst's lifespan. In this invention, the alkali metals and / or alkaline earth metals are preferably added in the form of soluble nitrates, acetates, or citrates.

[0056] Rare earth element cerium and alkali metals and / or alkaline earth metals can be added during the carrier molding process; they can also be added to the carrier after molding and before impregnation of the active component; or they can be added simultaneously with the impregnation solution of the active component during impregnation. This invention does not specify the loading method for the catalyst additives in detail. For example, an equal-volume impregnation method can be used, in which an aqueous solution containing cerium and soluble salts of alkali metals and / or alkaline earth metals is impregnated onto the carrier, dried at 80–150°C for 3–8 hours, and then calcined at 300–500°C for 3–8 hours.

[0057] The catalyst for the hydrogenation of reforming oil of this invention uses alumina with a leaf-like aggregate structure as the support. This leaf-like aggregate structure alumina uses inexpensive aluminum as a raw material and does not add a template agent. Hydrothermal treatment yields leaf-like aggregate alumina with a regular morphology. The preparation method of this invention has advantages such as low cost, simple operation, and simple synthesis conditions. Furthermore, the alumina prepared by this invention has a leaf-like aggregate structure, which is easy to separate and does not agglomerate during high-temperature calcination, maintaining its nanosheet morphology. Therefore, it can serve as an excellent catalyst support for the hydrogenation and deolefination reaction of reforming oil.

[0058] Before use, the catalyst of the present invention is preferably reduced with hydrogen at 150–300°C for 6–16 hours.

[0059] The technical solution of the present invention will be further described in detail below through specific embodiments.

[0060] Example 1

[0061] (1) Carrier preparation method: 56.9g aluminum sulfate, 16g aluminum nitrate, and 6.6g ammonium oxalate (molar ratio of aluminum ions to ammonium oxalate was 4) were added to 70ml of deionized water. After stirring and dissolving, the mixture was transferred to a hydrothermal reactor, and CO2 gas was introduced to 0.5MPa. The reaction was carried out at 160℃ for 10h in the hydrothermal reactor. After cooling to room temperature, the precipitate was filtered, washed, dried, shaped, and then calcined at 750℃ for 5h. The prepared alumina was analyzed by scanning electron microscopy, and the results are as follows: Figure 1 As shown, the morphology of alumina is a nano-leaf-like aggregate.

[0062] (2) Catalyst preparation method: The catalyst was prepared by a two-step impregnation method. In the first step, potassium nitrate and cerium nitrate were dissolved in water to prepare an impregnation solution, which was then impregnated onto the support prepared in step (1) by an equal volume impregnation method. The solution was dried at 120°C and calcined at 350°C for 4 hours to obtain a catalyst semi-finished product. In the second step, palladium chloride and chloroplatinic acid were dissolved in water to prepare an impregnation solution, which was then impregnated onto the catalyst semi-finished product by a supersaturated impregnation method. The solution was dried at 100°C and calcined at 450°C for 4 hours to obtain catalyst C1.

[0063] Based on the total weight of the catalyst (100%), the catalyst contains 0.25% palladium (C1), 0.10% platinum, 1.0% chlorine, 0.5% cerium, and 0.3% potassium, with the balance being the support. The catalyst has a specific surface area of ​​201 m². 2 / g, pore volume 0.58cm 3 / g, with a most probable pore size of 8.2nm.

[0064] Example 2

[0065] (1) Preparation method of carrier: Aluminum nitrate and ammonium bicarbonate (molar ratio of aluminum ions to ammonium bicarbonate is 0.2) are dissolved in deionized water. After stirring and dissolving, the mixture is transferred to a hydrothermal reactor. CO2 gas is introduced to 1.8 MPa and reacted in the hydrothermal reactor at 200°C for 24 h. After cooling to room temperature, the precipitate is filtered, washed, dried, shaped, and then calcined at 620°C for 4 h to obtain the leaf-shaped aggregate alumina carrier precursor.

[0066] (2) Catalyst preparation method: The catalyst was prepared by one-step impregnation method. Potassium nitrate, cerium nitrate, palladium chloride, chloroplatinic acid and hydrochloric acid were dissolved in water to prepare an impregnation solution, which was impregnated onto the support prepared in step (1) by equal volume impregnation method. The solution was dried at 120°C and calcined at 400°C for 4 hours to obtain catalyst C2.

[0067] Based on the total weight of the catalyst (100%), the catalyst contains 0.15% palladium (C2), 0.15% platinum, 0.8% chlorine, 0.1% cerium, and 0.8% potassium, with the balance being the support. The catalyst has a specific surface area of ​​220 m². 2 / g, pore volume 0.52cm 3 / g, with a most probable pore size of 7.0nm.

[0068] Example 3

[0069] (1) Carrier preparation

[0070] Aluminum sulfate and ammonium bicarbonate (molar ratio of aluminum ions to ammonium bicarbonate of 2.5) were dissolved in deionized water. After stirring and dissolving, the solution was transferred to a hydrothermal reactor, and CO2 gas was introduced to 0.15 MPa. The reaction was carried out at 120°C for 14 hours. After cooling to room temperature, the precipitate was filtered, washed, dried, and shaped. It was then dried at 120°C for 4 hours and calcined at 700°C for 4 hours to obtain a leaf-shaped aggregate alumina support precursor. An aqueous solution of lithium citrate and cerium nitrate was prepared and impregnated onto the support using an equal-volume impregnation method. The solution was dried at 100°C for 4 hours and calcined at 500°C for 5 hours to obtain a leaf-shaped aggregate alumina support containing lithium and cerium.

[0071] (2) Catalyst preparation

[0072] The catalyst was prepared by a one-step impregnation method. Palladium nitrate, platinum nitrate, and hydrochloric acid were dissolved in water to prepare an impregnation solution, which was then impregnated onto the support prepared in step (1) using an equal-volume impregnation method. The solution was dried at 120°C and calcined at 380°C for 6 hours to obtain catalyst C3.

[0073] Based on the total weight of the catalyst (100%), the catalyst contains 0.35% palladium (C3), 0.08% platinum, 1.3% chlorine, 1.1% cerium, and 1.8% lithium, with the balance being the support. The catalyst has a specific surface area of ​​185 m². 2 / g, pore volume 0.65cm 3 / g, with a most probable pore size of 11.1nm.

[0074] Example 4

[0075] (1) Carrier preparation

[0076] Aluminum sulfate, aluminum nitrate, and urea (molar ratio of aluminum ions to urea of ​​0.9) were added to deionized water and stirred until dissolved. The mixture was then transferred to a hydrothermal reactor, and CO2 gas was introduced to 1.2 MPa. The reaction was carried out at 150°C for 20 hours. After cooling to room temperature, the precipitate was filtered, washed, dried, and shaped. It was then dried at 120°C for 4 hours and calcined at 690°C for 4 hours to obtain a leaf-shaped aggregate alumina support precursor. A magnesium nitrate aqueous solution was prepared and impregnated onto the support using an equal-volume impregnation method. The solution was dried at 120°C for 4 hours and calcined at 450°C for 4 hours to obtain a magnesium-containing leaf-shaped aggregate alumina support.

[0077] (2) Catalyst preparation

[0078] The catalyst was prepared by a one-step impregnation method. Cerium nitrate, palladium chloride, chloroplatinic acid and trichloroacetic acid were dissolved in water to prepare an impregnation solution, which was then impregnated onto the support prepared in step (1) by an equal volume impregnation method. The solution was dried at 120°C and calcined at 500°C for 3 hours to obtain catalyst C4.

[0079] Based on the total weight of the catalyst (100%), the catalyst contains 0.20% C4 palladium, 0.28% platinum, 1.8% chlorine, 0.2% cerium, and 0.5% magnesium, with the balance being the support. The catalyst has a specific surface area of ​​216 m². 2 / g, pore volume 0.69cm 3 / g, with a most probable pore size of 9.1nm.

[0080] Example 5

[0081] (1) Carrier preparation

[0082] Aluminum nitrate, urea, and ammonium oxalate (molar ratio of aluminum ions to urea 3.0) were added to deionized water, stirred until dissolved, and then transferred to a hydrothermal reactor. CO2 gas was introduced to 0.8 MPa, and the reaction was carried out at 180°C for 4 hours. After cooling to room temperature, the precipitate was filtered, washed, dried, and shaped. It was then dried at 100°C for 4 hours and calcined at 750°C for 4 hours. An aqueous solution of lithium citrate and potassium nitrate was prepared and impregnated onto a support using an equal-volume impregnation method. The support was dried at 100°C for 4 hours and calcined at 350°C for 6 hours to obtain a lithium- and potassium-containing leaf-shaped aggregate structure alumina support.

[0083] (2) Catalyst preparation

[0084] The catalyst was prepared by a one-step impregnation method. Cerium nitrate, palladium nitrate and chloroplatinic acid were dissolved in water to prepare an impregnation solution, which was then impregnated onto the support prepared in step (1) by an equal volume impregnation method. The solution was dried at 120°C and calcined at 500°C for 3 hours to obtain catalyst C5.

[0085] Based on the total weight of the catalyst (100%), the catalyst contains 0.45% C4 palladium, 0.05% platinum, 0.10% chlorine, 1.6% cerium, 0.8% potassium, and 0.8% lithium, with the balance being the support. The catalyst has a specific surface area of ​​236 m². 2 / g, pore volume 0.55cm 3 / g, with a most probable pore size of 7.8nm.

[0086] Example 6

[0087] (1) Carrier preparation

[0088] Aluminum nitrate and ammonium carbonate (molar ratio of aluminum ions to ammonium carbonate of 1.0) were added to deionized water, stirred until dissolved, and then transferred to a hydrothermal reactor. CO2 gas was introduced to 0.9 MPa, and the reaction was carried out at 170°C for 8 hours. After cooling to room temperature, the precipitate was filtered, washed, dried, and shaped. It was then dried at 120°C for 4 hours and calcined at 700°C for 4 hours. An aqueous solution of lithium citrate and magnesium nitrate was prepared and impregnated onto a support using an equal-volume impregnation method. The support was dried at 120°C for 4 hours and calcined at 380°C for 4 hours to obtain a lithium- and magnesium-containing leaf-shaped aggregate structure alumina support.

[0089] (2) Catalyst preparation

[0090] The catalyst was prepared by a one-step impregnation method. Cerium nitrate, palladium chloride, and chloroplatinic acid were dissolved in water to prepare an impregnation solution, which was then impregnated onto the support prepared in step (1) using an equal-volume impregnation method. The solution was dried at 120°C and calcined at 450°C for 3 hours to obtain catalyst C6.

[0091] Based on the total weight of the catalyst (100%), the catalyst contains 0.30% C4 palladium, 0.10% platinum, 1.2% chlorine, 1.2% cerium, 0.5% lithium, and 0.5% magnesium, with the balance being the support. The catalyst has a specific surface area of ​​181 m². 2 / g, pore volume 0.65cm 3 / g, with a most probable pore size of 9.6nm.

[0092] Comparative Example 1

[0093] The substrate used was commercially available alumina. After calcination at 750℃ for 5 hours, the microstructure was irregular. The scanning electron microscope (SEM) image of the alumina substrate in Comparative Example 1 is shown below. Figure 2 As shown. Using the same preparation method as the catalyst in Example 1, the comparative catalyst D1 prepared had a specific surface area of ​​180 m². 2 / g, pore volume 0.55cm 3 / g, with a most probable pore size of 7.8nm, and the content of active component D1 in catalyst is the same as that in C1.

[0094] Comparative Example 2

[0095] Boehmite, prepared using a commercially available carbonization method, was extruded, dried at 120°C for 4 hours, and calcined at 620°C for 4 hours to obtain an alumina support. This alumina support does not possess a leaf-like aggregate structure. Using the same preparation method as the catalyst in Example 2, the comparative catalyst D2 obtained had a specific surface area of ​​210 m². 2 / g, pore volume 0.55cm 3 / g, with a most probable pore size of 7.2nm, and the content of active component D2 in catalyst is the same as that in C2.

[0096] Comparative Example 3

[0097] The preparation method of leaf-shaped nano-γ-alumina disclosed in Chinese Patent CN106276992B is as follows: 7.5g of aluminum nitrate and 6g of urea are added to 70ml of deionized water and magnetically stirred for 20 minutes to obtain a colorless and transparent solution. The solution is then transferred to a high-pressure reactor, and hydrogen gas is introduced to purge the air from the reactor. The hydrogen pressure in the reactor is then set to 0.5MPa, and the reactor is sealed. The reactor is heated to 140℃ and reacted for 12 hours. After the reaction, the reactor is allowed to cool naturally to room temperature, the gas inside the reactor is released, the reactor is opened, and the reaction slurry is collected. The slurry is filtered and dried to obtain boehmite monohydrate, which is mixed with nitric acid, phosphoric acid, guar gum powder, and water to form a plastic body. This body is then extruded into strips, dried at 120℃ for 4 hours, and calcined at 700℃ for 4 hours to obtain an amorphous alumina carrier. An aqueous solution of lithium citrate and cerium nitrate was prepared and impregnated onto a support using an equal-volume impregnation method. The mixture was then dried at 100°C for 4 hours and calcined at 500°C for 5 hours to obtain a lithium- and cerium-containing alumina support. Using the same preparation method as the catalyst in Example 3, the comparative catalyst D3 obtained had a specific surface area of ​​195 m². 2 / g, pore volume 0.60cm 3 / g, with a most probable pore size of 7.7nm, and the content of active component D3 in catalyst is the same as that in C3.

[0098] Catalyst evaluation

[0099] Catalyst pore size volume distribution:

[0100] The pore volume and pore distribution of the catalyst were determined using the BET method on an ASAP2400 static nitrogen adsorption analyzer manufactured by Micromeritics, USA. The proportion of pore volume with a diameter of 5–15 nm was statistically analyzed. A higher proportion indicates a higher degree of pore distribution concentration. A more concentrated pore distribution is more conducive to mass and heat transfer in the reaction, and will also result in higher hydrogenation activity, stability, and regeneration performance. The pore volume distribution results of the catalyst samples in the examples and comparative examples are shown in Table 1 below.

[0101] Table 1. Pore volume distribution of catalysts in the examples and comparative catalysts.

[0102] catalyst Percentage of pore volume in the 5–15 nm range / C1 88..6 C2 85.3 C3 90.6 D1 53.2 D2 61.0 D3 66.5

[0103] As can be seen from Table 1, the reforming oil hydrogenation catalyst prepared by the method of the present invention has a more concentrated pore size distribution, which is more conducive to the diffusion and mass transfer of olefin molecules during the hydrogenation reaction, and thus helps to improve the hydrogenation activity and stability.

[0104] Characterization of active metal dispersion in catalysts:

[0105] Metal dispersion was tested using CO pulses on a Micromeritics Autochem 2920 chemisorption analyzer. First, the sample was heated to 400℃ at a rate of 20℃ / min under an H2 / Ar (5:95, V / V) atmosphere and held at that temperature for 30 min. Then, the temperature was lowered to 50℃ at a rate of 30℃ / min, and pulsed 20 times under a CO / He (10:10, V / V) atmosphere. The specific results are shown in Table 2 below.

[0106] Table 2. Metal dispersion of catalysts in the examples and comparative catalysts.

[0107]

[0108]

[0109] As can be seen from the results in Table 2, the reforming oil hydrogenation catalyst prepared by the present invention has a better metal dispersion, indicating that the leaf-shaped alumina support has a better dispersion effect on the active metal loaded on it.

[0110] Catalyst performance evaluation:

[0111] The catalyst was loaded into a fixed-bed reactor and reduced at 200°C in a hydrogen atmosphere. The reaction was then carried out at a pressure of 1.8 MPa, an inlet temperature of 140°C, a hydrogen-to-oil volume ratio of 5:1, and a feed volume hourly space velocity of 8 h⁻¹. -1 Under the specified process conditions, hydrogenation activity and selectivity were evaluated, and the average hydrogenation results are shown in Table 3.

[0112] Olefin removal rate = [1-B p / B f ]*100%;

[0113] Aromatic hydrocarbon loss rate = [1-A] p / A f ]*100%;

[0114] In the formula: B p The bromine index of the reaction product is expressed in mgBr / 100g.

[0115] B f The bromine index of the raw material is expressed in mgBr / 100g.

[0116] A p The mass fraction of aromatic hydrocarbons in the reaction product, in %;

[0117] A f The aromatic hydrocarbon mass fraction of the raw material, in %;

[0118] Table 3. Hydrogenation performance results of catalysts in the examples and comparative examples.

[0119] serial number Olefin removal rate (%) Aromatic hydrocarbon loss rate (%) C1 99.1 0.08 C2 98.8 0.05 C3 99.6 0.10 C4 99.6 0.25 C5 99.8 0.12 C6 99.5 0.07 D1 95.6 0.10 D2 89.0 0.11 D3 94.4 0.79

[0120] Table 3 shows that, under the same process conditions, the reformate hydrotreating catalyst prepared according to this invention exhibits a higher olefin removal rate and a lower aromatic loss rate, indicating that the hydrogenation activity and selectivity of the reformate hydrotreating catalyst prepared according to this invention are superior. The better hydrogenation activity and selectivity of the catalyst in the examples stem from the alumina support, with its nano-leaf-like aggregates, which provides better dispersion of the active components, a pore structure more conducive to oil molecule diffusion, a greater number of active centers, and more favorable mass transfer and diffusion, while also preventing coke deposition.

[0121] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A reforming hydrotreated catalyst for generating oil, characterized by, The catalyst comprises a carrier, an active component and an auxiliary agent, the carrier is alumina, the alumina has a leaf-like aggregate structure, the active component comprises palladium and platinum; the auxiliary agent comprises cerium and chlorine, and further comprises an alkali metal and / or an alkaline earth metal; the content of the active component palladium is 0.05-0.50 wt% in terms of metal, the content of platinum is 0.05-0.50 wt% in terms of metal, the content of the auxiliary agent cerium is greater than 0 and less than or equal to 2.0 wt% in terms of metal, the content of chlorine is 0.1-2.0 wt% in terms of element, and the content of the auxiliary agent alkali metal and / or alkaline earth metal is greater than 0 and less than or equal to 2.0 wt% in terms of metal; The preparation method of the alumina comprises: Step 1, adding a compound capable of decomposing into NH3 and CO2 into an aqueous inorganic aluminum salt solution, stirring until completely dissolved to form a mixed solution; Step 2, introducing CO2 gas with a pressure of 0.1-2 MPa into a closed container containing the mixed solution, performing hydrothermal treatment, and calcining to obtain the alumina.

2. The reforming naphtha hydrogenation catalyst according to claim 1, characterized by, The catalyst has a specific surface area of 150 to 300 m 2 / g; a pore volume of 0.30 to 0.70 ml / g; and a most probable pore diameter of 5 to 15 nm.

3. The reforming gas oil hydrogenation catalyst according to claim 1, characterized by, The catalyst has a specific surface area of 170 to 250 m 2 / g; a pore volume of 0.45 to 0.70 ml / g; and a most probable pore diameter of 5 to 10 nm.

4. The reforming gas oil hydrogenation catalyst according to claim 1, characterized by, The content of palladium is 0.1-0.3 wt% in terms of metal, the content of platinum is 0.05-0.2 wt% in terms of metal, the content of chlorine is 0.5-1.2 wt% in terms of element, the content of cerium is 0.1-1.0 wt% in terms of metal, and the content of the alkali metal and / or alkaline earth metal is 0.3-1.0 wt% in terms of metal.

5. The reforming gas oil hydrogenation catalyst according to claim 1, wherein The compound capable of decomposing into NH3 and CO2 is at least one selected from the group consisting of ammonium carbonate, ammonium bicarbonate, urea and ammonium oxalate.

6. The reforming gas oil hydrogenation catalyst according to claim 1, characterized by, The molar ratio of the inorganic aluminum salt to the compound capable of decomposing into NH3 and CO2 is 0.1-4.0 in terms of aluminum ions in the aqueous inorganic aluminum salt solution; the inorganic aluminum salt is at least one selected from the group consisting of aluminum sulfate, aluminum nitrate and aluminum chloride.

7. The reforming gas oil hydrogenation catalyst according to claim 1, wherein The molar ratio of the inorganic aluminum salt to the compound capable of decomposing into NH3 and CO2 is 0.5-3 in terms of aluminum ions in the aqueous inorganic aluminum salt solution.

8. The reforming gas oil hydrogenation catalyst according to claim 1, wherein The temperature of the hydrothermal treatment is 120-200 DEG C, the time of the hydrothermal treatment is 4-24 h, the calcination temperature is 550-800 DEG C, and the calcination time is 3-8 h.

9. The reforming gas oil hydrogenation catalyst according to claim 1, wherein The preparation method of the catalyst comprises loading a precursor of an active component on the alumina, the precursor of the active component comprising a soluble compound of palladium and a soluble compound of platinum.

10. The reforming gas oil hydrogenation catalyst according to claim 9, characterized by, The preparation method of the catalyst further comprises loading a precursor of an auxiliary agent on the alumina carrier, the precursor of the auxiliary agent comprising a soluble salt of cerium, a soluble acid or salt containing chlorine, and a soluble salt of an alkali metal or a soluble salt of an alkaline earth metal.

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