Preparation methods of unsupported metal active phases, unsupported hydrocracking catalysts and their applications

Abstract

This invention provides a method for preparing an unsupported metal active phase, comprising the following steps: 1) mixing a compound of a Group VIII element, a compound of a Group VIB element, and a protic liquid with a pH of 6-11 to form a slurry, then placing the mixture in a sealed container and reacting it at a temperature not lower than 80°C. After the reaction is complete, the mixture is cooled to obtain a post-reaction solution; 2) mixing the solution containing the compounds of the Group VIII element and the Group VIB element with the post-reaction solution obtained in step 1), adjusting the pH to 7-10, and then placing the mixture in a sealed container and reacting it at a temperature of 50-200°C. After the reaction is complete, the mixture is filtered and dried to obtain the unsupported metal active phase. This invention, by adjusting each step, achieves morphological control of the unsupported metal active phase, improves the selectivity of hydrogenation saturation and hydrogenation ring-opening reactions in the hydrocracking process, thereby obtaining high-quality ethylene feedstock.

Description

Technical Field

[0001] This invention belongs to the field of hydrocracking catalyst preparation, specifically relating to a method for preparing an unsupported metal active phase, an unsupported hydrocracking catalyst, and its application. Background Technology

[0002] Unsupported catalysts refer to catalysts obtained by mixing and molding active components (including metal components, acidic components, etc.) with molding components. Traditional supported catalysts require the metal active component to be prepared into a solution and then impregnated onto a catalyst support. This process is limited by both the solution preparation and the support's capacity to hold the metal active component. Therefore, the metal oxide mass (based on the total catalyst weight) of conventional supported catalysts is no more than 40%. In contrast, the metal active component content in unsupported catalysts can be adjusted according to their molding method. Because unsupported catalysts are synthesized using molding methods, changes in the active phase content do not significantly affect the catalyst's pore properties, and there is no pore blockage caused by co-precipitation processes in porous materials such as amorphous silica, molecular sieves, and alumina. Typically, the metal oxide active component content (based on the total catalyst weight) in unsupported catalysts (bulk catalysts) is 60%–90%. Therefore, compared to supported catalysts, unsupported catalysts can exhibit higher catalytic activity per unit volume.

[0003] Chinese patent document CN110975908A discloses a method for preparing a bulk catalyst. The method involves first treating the catalyst at a low temperature, followed by hydrothermal treatment at a higher temperature. This allows the multiple metal component solutions to react initially at a lower temperature, providing a buffering process for crystal formation. Then, conventional hydrothermal treatment is performed at a higher temperature. This approach improves the desulfurization and denitrification catalytic activity of the resulting bulk catalyst. Furthermore, by recycling the filtrate obtained after the reaction, the liquid product can be used as a solvent for the Group VIB metal component compounds in the next reaction, resulting in no waste liquid generated during the preparation process.

[0004] Chinese patent document CN110975910A discloses a method for recycling filtrate and synthesizing a bulk catalyst without producing filtrate. By controlling the amount of solvent added during the preparation of the bulk catalyst to be 1-2 times the saturated water absorption volume of the added powder compound containing Group VIII elements, the bulk catalyst product obtained after the reaction is a moist solid, eliminating the need for a filtration step and thus preventing the generation of reaction waste liquid, avoiding environmental pollution, and eliminating the cumbersome treatment steps for reaction waste liquid.

[0005] Chinese patent document CN112774722A discloses a selective ring-opening catalyst for cycloalkanes and aromatics and its preparation method. Using ZSM-5 as the acidic component in the support, and employing a supported catalyst with tetrahydronaphthalene as the model compound, the selectivity for ring-opening of cycloalkanes and aromatics was investigated. The main problems addressed are the poor conversion rate and inconsistent hydrothermal stability of the selective ring-opening catalyst for cycloalkanes and aromatics.

[0006] Chinese patent document CN112742457A discloses a hydrocracking catalyst, specifically utilizing two different Y-type molecular sieves and an MFI-structured molecular sieve as acidic components in the support. Through a supported catalyst configuration, using catalytic diesel as feedstock, the selective ring-opening ability of cycloalkanes and aromatics was investigated. The catalyst exhibits high ring-opening activity for polycyclic aromatic hydrocarbons, high side-chain breaking performance for alkyl aromatic hydrocarbons, and high retention of monocyclic aromatic hydrocarbons. The hydrocracking reaction of polycyclic aromatic hydrocarbons can improve the yield of C6-C10 and C6-C8 light aromatic hydrocarbons.

[0007] Chinese patent document CN112742459A discloses a hydrocracking catalyst, specifically utilizing two different Y-type molecular sieves as acidic components in the support. Through a supported catalyst configuration, using catalytic diesel as feedstock, the selective ring-opening ability of cycloalkanes and aromatics was investigated. The catalyst exhibits high selective hydrogenation saturation performance for polycyclic aromatic hydrocarbons, excellent ring-opening reaction performance, and high retention rate of monocyclic aromatic hydrocarbons.

[0008] Chinese patent document CN111822040A discloses a bulk hydrocracking catalyst and its preparation method. The method involves forming a slurry containing metal components, amorphous silica-alumina, molecular sieves, and alumina through a co-precipitation method, followed by gelation and aging, and finally obtaining the bulk hydrocracking catalyst through a molding process. The bulk catalyst synthesized using this method allows for the control of the active phase morphology, improving the catalyst's activity and stability in treating high-nitrogen feedstocks.

[0009] Chinese patent document CN112570037A discloses a partially sulfided bulk catalyst after reduction. This bulk catalyst is used in the hydrotreating process of hydrocarbon feedstocks and exhibits excellent activity in the hydrotreating of hydrocarbon feedstocks, especially in hydrodearomatization. However, the product obtained from hydrodearomatization using this catalyst is mainly used for removing polycyclic aromatic hydrocarbons from diesel fractions to meet the requirements of China VI diesel blending components.

[0010] The unsupported catalysts (bulk catalysts) disclosed in the aforementioned literature are mainly for diesel hydrorefining, while supported catalysts are primarily used to improve the yield of aromatics. Neither can be used for diesel hydrocracking to produce feedstock for ethylene production. Therefore, designing a novel unsupported metallic active phase for the diesel hydrocracking reaction process to improve the ethylene yield from the steam cracking feedstock produced by diesel hydrocracking is of great significance for addressing the current dual problems of diesel overproduction and ethylene feedstock shortage. Summary of the Invention

[0011] The main objective of this invention is to provide a method for preparing a non-supported metal active phase, thereby overcoming the deficiency in the prior art where the catalyst does not have the ability to be used as a feedstock for the hydrocracking of ethylene.

[0012] To achieve the above objectives, the present invention provides a method for preparing a non-supported metal active phase, comprising the following steps:

[0013] 1) After mixing compounds of Group VIII elements and Group VIB elements with a protic liquid with pH 6 to 11 to form a slurry, the mixture is placed in a sealed container and reacted at a temperature not lower than 80°C. After the reaction is completed, the mixture is cooled to obtain the reaction solution.

[0014] 2) The solution containing Group VIII and Group VIB elements is mixed with the post-reaction solution obtained in step 1), the pH is adjusted to 7-10, and then placed in a sealed container for reaction at 50-200°C. After the reaction is completed, the solution is filtered and dried to obtain the unsupported metal active phase.

[0015] In step (1), the ratio of the protonated liquid with pH 6–11 to the compounds of Group VIII and Group VIB elements is not specifically limited, as long as the slurry formed after mixing the protonated liquid with pH 6–11 with the compounds of Group VIII and Group VIB elements is fluid. In step (2), the ratio of the solution containing the compounds of Group VIII and Group VIB elements to the reaction solution obtained in step (1) is not limited, as long as all Group VIII and Group VIB elements in the mixed system exist in ionic form.

[0016] Optionally, in step 1), the cooling is to lower the temperature to a temperature at which compounds of Group VIB elements do not decompose.

[0017] Preferably, in step 1), the cooling process involves reducing the temperature to 25–40°C.

[0018] Optionally, in step 1), the components of the protic liquid may be selected from at least one of the filtrate obtained by filtration in step 2), an acidic substance, an alkaline substance, and water.

[0019] Optionally, in step 2), an acidic or alkaline substance is used to adjust the pH value.

[0020] Optionally, the acidic substance is selected from nitric acid, acetic acid, or ammonium nitrate, and the alkaline substance is selected from ammonia, urea, or ammonium carbonate.

[0021] Optionally, the compounds of the group VIII elements are calculated as group VIII elements, and the compounds of the group VIB elements are calculated as group VIB elements. In steps 1) and 2), the molar ratio of the compounds of the group VIII elements to the compounds of the group VIB elements is 20:1 to 1:20.

[0022] Optionally, the group VIII element in the compound is cobalt and / or nickel; the group VIB element in the compound is molybdenum and / or tungsten; and the molar ratio of the group VIII element compound to the group VIB element compound is 4:1 to 1:4.

[0023] Optionally, in step 1), the compound of the group VIII element is an inorganic substance with a group VIII element valence state of +2 or +3 and is not water-soluble (an inorganic substance that is insoluble in the protic liquid at room temperature); the compound of the group VIB element is an inorganic substance with a group VIB element valence state of +4 or +6 and is soluble in the protic liquid; preferably, the compound of the group VIII element is at least one of basic nickel carbonate, basic cobalt carbonate and nickel carbonate, and the compound of the group VIB element is ammonium heptamolybdate and / or ammonium metatungstate.

[0024] Optionally, in step 2), the compound containing a group VIII element is an inorganic compound in which the group VIII element has a valence state of +2 or +3; the compound containing a group VIB element is an inorganic compound in which the group VIB element has a valence state of +4 or +6; preferably, the compound containing a group VIII element is at least one of nickel nitrate, cobalt nitrate, and nickel acetate; the compound containing a group VIB element is ammonium heptamolybdate and / or ammonium metatungstate.

[0025] Optionally, in step 1), the reaction temperature is 80–120°C and the time is 1–3 hours.

[0026] Optionally, in step 2), the reaction temperature is 50–150°C and the time is 2–12 hours.

[0027] The present invention also provides a non-supported hydrocracking catalyst, wherein the active component is the non-supported metal active phase prepared by the above-described method.

[0028] The unsupported metal active phase can be prepared into an unsupported hydrocracking catalyst by molding. The specific preparation method is not limited; conventional methods are acceptable. For example, the unsupported metal active phase obtained by the above-described method, molecular sieve, and binder can be mixed, molded, dried, and calcined to obtain the unsupported hydrocracking catalyst. Furthermore, the content of the unsupported metal active phase, molecular sieve, and binder during molding is not particularly limited, nor are the types of molecular sieve and binder particularly limited; they can be selected and adjusted according to actual needs. For example, 70g of unsupported metal active phase, 10g of Y-type molecular sieve, and 20g of pseudoboehmite can be used.

[0029] The present invention also provides the application of the unsupported metal active phase prepared by the above-mentioned method or the above-mentioned unsupported hydrocracking catalyst in the hydrocracking of petroleum products (such as diesel) to produce ethylene feedstock.

[0030] Before hydrocracking, the unsupported hydrocracking catalyst needs to be pre-sulfurized. The reaction conditions and feedstock for the pre-sulfurization process are not particularly limited and can be selected and adjusted according to actual needs. For example, using straight-run diesel containing 2wt% CS2, the reaction conditions are: reaction temperature: 360℃; liquid hourly space velocity: 2.0 h⁻¹. -1 Sulfurization was carried out under the condition that the volume ratio of hydrogen to sulfurized oil was 300:1.

[0031] In the hydrocracking process, unsupported hydrocracking catalysts need to be used in a graded manner with hydrorefining catalysts. There are no special restrictions on the catalyst gradation scheme. However, it is necessary to control the nitrogen content in the reactants to be below 10 ppm when the reactants enter the hydrocracking catalyst.

[0032] The reaction conditions for using unsupported hydrocracking catalysts in the hydrocracking of petroleum products are not particularly limited and can be adjusted according to actual needs. For example, when using straight-run diesel hydrocracking, the reaction temperature can be 350℃, the reaction pressure 7.0 MPa, and the liquid hourly space velocity 1.5 h⁻¹. -1 The reaction was carried out under the condition that the volume ratio of hydrogen to straight-run diesel was 300:1.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] 1. This invention aims to design a novel unsupported metal active phase for the diesel hydrocracking reaction process, thereby increasing the ethylene yield of the diesel hydrocracking feedstock for steam cracking. By controlling the preparation method of the unsupported metal active phase, the morphology of the unsupported metal active phase can be controlled, thus optimizing the bonding state between the metal active phase and the molecular sieve. Through the optimization of the bonding state, the hydrogen overflow from the metal active centers in the hydrocracking catalyst's metal active phase to the acidic centers in the molecular sieve can be regulated, improving the selectivity of hydrogenation saturation and hydrogenation ring-opening reactions in the hydrocracking process, thereby obtaining high-quality ethylene feedstock.

[0035] 2. For feedstocks used in ethylene production via cracking, generally, the higher the alkane content and the lower the BMCI value (less than 20) in the steam cracking feedstock, the higher the ethylene yield. However, existing bulk catalysts and supported catalysts cannot meet these requirements. Although existing catalysts can achieve hydrodearomatization and reduce the BMCI value of the product, the resulting product cannot be used as a feedstock for ethylene production (low alkane content, low BMCI value). Therefore, to improve the yield of feedstocks for ethylene production from diesel hydrocracking, it is necessary to improve the selectivity of hydrogenation saturation and hydrogenation ring-opening in the diesel hydrocracking process. Through in-depth research, the inventors discovered that adding Group VIII and Group VIB element compounds in two batches—the first batch forming a slurry and generating crystal nuclei, and the second batch, combined with adjusting the pH to 7-10 to prevent precipitation—provides a richer supply of Group VIII elements around the crystal nuclei, thus aiding crystal growth. The resulting unsupported metal active phase is more conducive to contact with molecular sieves, exhibiting excellent selectivity for hydrogenation saturation and ring-opening. Catalysts using this unsupported metal active phase as the active component produce products with higher alkane content and lower BMCI values ​​(less than 20), resulting in higher yields of ethylene as a steam cracking feedstock.

[0036] 3. Under normal conditions, the synthesis of unsupported metal active phases involves simultaneously treating compounds containing Group VIII elements and compounds containing Group VIB elements during a hydrothermal process. In this reaction, there is no interference with the crystal growth direction of the compounds containing Group VIII and Group VIB elements. The method for preparing unsupported metal active phases provided by this invention involves synthesis under normal conditions, followed by cooling treatment. The pH value of the system is strictly controlled, and soluble compounds containing Group VIII and Group VIB elements are added, providing a suitable environment for the directional crystal growth of the unsupported metal active phase. By strictly controlling the preparation process, the morphology of the unsupported metal active phase can be controlled, thereby optimizing the bonding state between the metal active phase and the molecular sieve. If the step of adjusting the pH value in step 2) is omitted, and / or the step of adding water-soluble Group VIII and Group VIB element compounds in step 2) is omitted, or even if the water-soluble Group VIII and Group VIB element compounds are added in step 1), the resulting unsupported metal active phase is very compact. When used for diesel hydrocracking, the product has a lower alkane content and a higher BMCI value, and cannot be used as feedstock for ethylene cracking. Attached Figure Description

[0037] Figure 1 This is a SEM image of the unsupported metal active phase obtained in Example 1 of the present invention;

[0038] Figure 2 This is a SEM image of the unsupported metal active phase prepared in Comparative Example 1 of this invention. Detailed Implementation

[0039] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0040] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0041] Example 1

[0042] 1) Weigh 160 mL of water, adjust the pH of the system to 8 using ammonia, and then mix 37.62 g of basic nickel carbonate and 22.24 g of ammonium metatungstate with the above liquid to form a slurry. Place the slurry in a sealed reactor and hydrothermally react at 100°C for 2 hours, then cool it to 30°C. This is recorded as system A-1.

[0043] 2) Weigh 40 mL of water, mix 10.28 g of nickel nitrate and 5.56 g of ammonium metatungstate to form a solution, then transfer the solution to system A-1 and mix thoroughly. Adjust the pH of the system to 7 using nitric acid, and then seal the reactor. Perform a hydrothermal reaction at 120 °C for 4 hours, followed by cooling and filtration. Dry the filtered solid at 120 °C for 6 hours to obtain the unsupported metal active phase B-1.

[0044] Example 2

[0045] 1) Weigh 80 mL of water, adjust the pH of the system to 6 using acetic acid, and then mix 16.98 g of basic nickel carbonate, 0.28 g of basic cobalt carbonate, 4.04 g of ammonium metatungstate, and 1.28 g of ammonium heptamolybdate with the above liquid to form a slurry. Place the slurry in a sealed reactor and hydrothermally react at 80°C for 4 hours, then cool it to 20°C. This is recorded as system A-2.

[0046] 2) Weigh 120 mL of water, mix 20.56 g of nickel nitrate and 2.88 g of ammonium metatungstate to form a solution, then transfer the solution to system A-2 and mix thoroughly. Adjust the pH of the system to 8 using ammonium carbonate, and then seal the reactor. Perform a hydrothermal reaction at 180 °C for 2 hours, followed by cooling and filtration. Dry the filtered solid at 120 °C for 6 hours to obtain the unsupported metal active phase B-2.

[0047] Example 3

[0048] 1) Weigh 100 mL of water, adjust the pH of the system to 11 using ammonia, then mix 23.54 g of basic nickel carbonate, 4.21 g of ammonium metatungstate, and 0.34 g of ammonium heptamolybdate with the above liquid to form a slurry. Place the slurry in a sealed reactor and hydrothermally react at 110°C for 2 hours, then cool to 35°C. This is designated as system A-3.

[0049] 2) Weigh 100 mL of water and mix 20.56 g of nickel nitrate and 2.88 g of ammonium metatungstate to form a solution. Transfer the solution to system A-3 and mix thoroughly. Adjust the pH of the system to 10 using ammonia water, and then seal the reactor. Perform a hydrothermal reaction at 60 °C for 10 hours, followed by cooling and filtration. Dry the filtered solid at 120 °C for 6 hours to obtain the unsupported metal active phase B-3.

[0050] Example 4

[0051] 1) Weigh 100 mL of water, adjust the pH of the system to 11 using ammonia, then mix 23.54 g of basic nickel carbonate, 4.21 g of ammonium metatungstate, and 0.34 g of ammonium heptamolybdate with the above liquid to form a slurry. Place the slurry in a sealed reactor and hydrothermally react at 110°C for 2 hours, then cool to 35°C. This is designated as system A-4.

[0052] 2) Weigh 100 mL of water and mix 20.56 g of nickel nitrate and 2.88 g of ammonium metatungstate to form a solution. Transfer the solution to system A-4 and mix thoroughly. Adjust the pH of the system to 10 using ammonia water, and then seal the reactor. Perform a hydrothermal reaction at 140℃ for 5 hours, followed by cooling and filtration. Dry the filtered solid at 120℃ for 6 hours to obtain the unsupported metal active phase B-4.

[0053] Example 5

[0054] 1) Weigh 160 mL of water, adjust the pH of the system to 6 using nitric acid, and then mix 35.61 g of nickel carbonate and 4.04 g of ammonium metatungstate with the above liquid to form a slurry. Place the slurry in a sealed reactor and hydrothermally react at 90°C for 3 hours, then cool to 35°C. This is recorded as system A-5.

[0055] 2) Weigh 40 mL of water, mix 5.14 g of nickel nitrate and 8.09 g of ammonium metatungstate to form a solution, then transfer the solution to system A-5 and mix thoroughly. Adjust the pH of the system to 7 using nitric acid, and then seal the reactor. Perform a hydrothermal reaction at 180 °C for 6 hours, followed by cooling and filtration. Dry the filtered solid at 120 °C for 6 hours to obtain the unsupported metal active phase B-5.

[0056] Example 6

[0057] 1) Weigh 140 mL of water, adjust the pH of the system to 7 using ammonium bicarbonate, and then mix 38.15 g of nickel carbonate, 0.54 g of basic cobalt carbonate, 5.36 g of ammonium heptamolybdate, and 22.24 g of ammonium metatungstate with the above liquid to form a slurry. Place the slurry in a sealed reactor and hydrothermally react at 100°C for 5 hours, then cool it to 30°C. This system is designated as system A-6.

[0058] 2) Weigh 60 mL of water, mix 6.28 g of nickel acetate and 6.80 g of ammonium metatungstate to form a solution, then transfer the solution to system A-6 and mix thoroughly. Adjust the pH of the system to 9 using ammonium carbonate, and then seal the reactor. Perform a hydrothermal reaction at 160 °C for 5 hours, then cool and filter. Dry the filtered solid at 120 °C for 6 hours to obtain the unsupported metal active phase B-6.

[0059] Example 7

[0060] 1) Weigh 120 mL of water, adjust the pH of the system to 8 using ammonium carbonate, and then mix 30.10 g of basic nickel carbonate, 1.76 g of ammonium heptamolybdate, and 2.72 g of ammonium metatungstate with the above liquid to form a slurry. Place the slurry in a sealed reactor and hydrothermally react at 110 °C for 4 hours, then cool it to 25 °C. This is recorded as system A-7.

[0061] 2) Weigh 80 mL of water, mix 11.60 g of nickel nitrate and 43.02 g of ammonium metatungstate to form a solution, then transfer the solution to system A-7 and mix thoroughly. Adjust the pH of the system to 8 using citric acid, and then seal the reactor. Perform a hydrothermal reaction at 200℃ for 7 hours, followed by cooling and filtration. Dry the filtered solid at 120℃ for 6 hours to obtain the unsupported metal active phase B-7.

[0062] Example 8

[0063] 1) Weigh 180 mL of water, adjust the pH of the system to 9 using ammonia, and then mix 21.21 g of basic nickel carbonate, 0.14 g of basic cobalt carbonate, 3.40 g of ammonium heptamolybdate, and 8.82 g of ammonium metatungstate with the above liquid to form a slurry. Place the slurry in a sealed reactor and hydrothermally react at 120°C for 3 hours, then cool it to 20°C. This is designated as system A-8.

[0064] 2) Weigh 20 mL of water, mix 0.20 g of nickel acetate and 4.30 g of ammonium metatungstate to form a solution, then transfer the solution to system A-8 and mix thoroughly. Adjust the pH of the system to 10 using ammonia water, and then seal the reactor. Perform a hydrothermal reaction at 100 °C for 4 hours, then cool and filter. Dry the filtered solid at 120 °C for 6 hours to obtain the unsupported metal active phase B-8.

[0065] Comparative Example 1

[0066] The unsupported metal active phase prepared in this comparative example was prepared according to the method described in Chinese patent document CN110975908A, which describes its application in the field of diesel hydrorefining: 8.83 g of ammonium heptamolybdate and 13.48 g of ammonium metatungstate were weighed and added to 30 g of water to prepare a homogeneous mixture. Ammonia solution with a mass concentration of 25% was added dropwise to the system until the pH of the solution reached 9, and then 12.54 g of basic nickel carbonate was stirred until homogeneous. The system was placed in a sealed reactor and reacted at 35°C for 2 h, then the temperature was raised to 150°C and reacted for 2 h. After cooling, filtration, and washing with water, the filter cake was dried at 120°C for 4 h to obtain the unsupported metal active phase D-1.

[0067] The unsupported metal active phases prepared in Example 1 and Comparative Example 1 were subjected to electro-optic scanning under the same conditions, as detailed in [link to details]. Figure 1 and Figure 2As shown. By Figure 1 and Figure 2 The comparison shows that the preparation method provided by this invention can better control the growth of the unsupported active phase. The obtained unsupported active phase has a relatively uniform size and a relatively loose composition. In the synthesis of unsupported hydrocracking catalysts, this is beneficial for the contact between the active phase and the molecular sieve surface, thereby helping to improve the activity and selectivity of the hydrocracking catalyst. In contrast, the unsupported metal active phase obtained in Comparative Example 1 has a relatively dense composition, which is not conducive to the dispersion of the metal active phase during the forming process.

[0068] Comparative Example 2

[0069] The unsupported metal active phase prepared in this comparative example was prepared according to the method described in Chinese patent document CN111822040A: Nickel chloride and ammonium metatungstate solutions were dissolved in deionized water, and 106 g of polyacrylic acid (molecular weight 3000) and 58 g of hydroxyethylidene diphosphonic acid were added to prepare solution A. In solution A, the mass concentration of Ni (calculated as NiO) was 22 g / L, and the mass concentration of W (calculated as WO3) was 16 g / L. Ammonium metatungstate and aluminum chloride solutions were dissolved in deionized water, and a dilute water glass solution was added to prepare solution B. In solution B, the mass concentration of W (calculated as WO3) was 24 g / L, the mass concentration of Al (calculated as Al2O3) was 25 g / L, and the mass concentration of Si (calculated as SiO2) was 21 g / L. Deionized water was added to the reaction vessel. A sodium aluminate solution with a mass concentration of 18 g / L (calculated as Al2O3) and solution A were added to the reaction vessel in parallel flow. The gelation temperature was maintained at 58℃. During the parallel flow gelation reaction, the pH value was controlled at 7.6 and the gelation time was controlled at 30 minutes to generate slurry I. The resulting slurry I was aged at 75°C, with the pH controlled at 6.7, for 0.5 hours under stirring. After aging, the slurry was filtered. The filter cake, Y-type molecular sieve suspension, and solution B were mixed, with the Y-type molecular sieve added at 10 wt% of the total catalyst weight. The mixture was stirred until homogeneous. Ammonia solution with a mass percentage concentration of 10 wt% was added dropwise to the mixture of slurry I, filter cake, molecular sieve, and solution B. The gelation temperature was maintained at 62°C, and the pH was controlled at 7.6 during the gelation reaction, with the gelation time controlled at 2 hours. After the reaction, slurry II was obtained and aged under stirring at 75°C, with the pH controlled at 8.2, for 3 hours. The aged slurry was filtered, and the filter cake was dried at 100°C for 12 hours, rolled, and extruded into strips. The strips were washed 6 times with deionized water at room temperature. The wet strips were then dried at 80°C for 10 hours and calcined at 530°C for 4 hours to obtain hydrocracking catalyst A. Of these, the nickel and tungsten introduced through solution A account for 70% of the total weight of nickel and tungsten in hydrocracking catalyst A.

[0070] The unsupported metal active phases obtained in each embodiment and Comparative Example 1 were molded into unsupported hydrocracking catalysts, which were then used together with the catalyst obtained in Comparative Example 2 to evaluate their activity in straight-run diesel hydrocracking. The molding method for the unsupported metal active phases included the following steps:

[0071] 70g of unsupported metal active phase, 10g of Y-type molecular sieve and 20g of binder pseudoboehmite were mixed (dry mixing followed by wet mixing); then shaped, dried at 100℃ until the weight no longer decreased, and calcined at 450℃ until the weight no longer changed, thus obtaining the unsupported hydrocracking catalyst.

[0072] The activity of the obtained unsupported hydrocracking catalyst in the hydrocracking of straight-run diesel was evaluated, and the specific results are shown in Table 1. The reaction conditions for the hydrocracking of straight-run diesel were: reaction temperature 350℃; reaction pressure 7.0 MPa; liquid hourly space velocity 1.5 h⁻¹. -1 The volume ratio of hydrogen to straight-run diesel was 300:1. All evaluated catalyst gradations were identical.

[0073] Table 1. Activity evaluation data of unsupported hydrocracking catalysts prepared with different metal active phases

[0074]

[0075] The data in the table above show that the unsupported catalysts with B-1 to B-8 metal active phases prepared using the technical solution of this invention have comparable yields of the >180℃ fraction compared to the comparative example. Regarding alkane content and BMCI value, the catalysts with B-1 to B-8 metal active phases have higher alkane content and lower BMCI values. Both higher alkane content and lower BMCI values ​​contribute to improving the ethylene yield of the steam cracking feedstock. The evaluation results indicate that the unsupported metal active phases prepared using the technical solution of this invention are more conducive to producing higher yields of ethylene from diesel hydrocracking steam cracking feedstocks.

[0076] 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. The application of a non-supported metal active phase in the feedstock for ethylene production via hydrocracking of petroleum products, characterized in that, The preparation method of unsupported metal active phase includes the following steps: 1) After mixing compounds of Group VIII elements and Group VIB elements with a protic liquid with pH 6 to 11 to form a slurry, the mixture is placed in a sealed container and reacted at a temperature not lower than 80°C. After the reaction is completed, the mixture is cooled to obtain the reaction solution. 2) The solution containing Group VIII and Group VIB elements is mixed with the post-reaction solution obtained in step 1), the pH is adjusted to 7-10, and then placed in a sealed container for reaction at 50-200°C. After the reaction is completed, the solution is filtered and dried to obtain the unsupported metal active phase.

2. The application as described in claim 1, characterized in that, In step 1), the cooling is to lower the temperature to a temperature at which compounds of Group VIB elements do not decompose.

3. The application as described in claim 1, characterized in that, The compounds of the group VIII elements are calculated as group VIII elements, and the compounds of the group VIB elements are calculated as group VIB elements. In steps 1) and 2), the molar ratio of the compounds of the group VIII elements to the compounds of the group VIB elements is 20:1 to 1:

20.

4. The application as described in claim 3, characterized in that, The group VIII element in the compound is cobalt and / or nickel; the group VIB element in the compound is molybdenum and / or tungsten; the molar ratio of the group VIII element compound to the group VIB element compound is 4:1 to 1:

4.

5. The application as described in claim 1, characterized in that, In step 1), the compounds of group VIII elements are inorganic substances in which the group VIII element has a valence state of +2 or +3 and is not water-soluble; the compounds of group VIB elements are inorganic substances in which the group VIB element has a valence state of +4 or +6 and is soluble in the protic liquid.

6. The application as described in claim 1, characterized in that, In step 2), the compounds containing group VIII elements are water-soluble inorganic compounds in which the group VIII elements have a valence state of +2 or +3; the compounds containing group VIB elements are inorganic compounds in which the group VIB elements have a valence state of +4 or +6.

7. The application as described in claim 1, characterized in that, In step 1), the reaction temperature is 80–120°C and the time is 1–3 hours.

8. The application as described in claim 1, characterized in that, In step 2), the reaction temperature is 50–150°C and the time is 2–12 hours.

9. The application as described in claim 5, characterized in that, The compound of the group VIII element is at least one of basic nickel carbonate, basic cobalt carbonate, and nickel carbonate, and the compound of the group VIB element is ammonium heptamolybdate and / or ammonium metatungstate.

10. The application as described in claim 6, characterized in that, The compound of the Group VIII element is at least one of nickel nitrate, cobalt nitrate, and nickel acetate; the compound of the Group VIB element is ammonium heptamolybdate and / or ammonium metatungstate.

11. The application of a non-supported hydrocracking catalyst in the feedstock for the hydrocracking of petroleum products to produce ethylene, characterized in that, The active component is the non-supported metal active phase prepared by the method described in any one of claims 1-10 for the application of the non-supported metal active phase in the hydrocracking of petroleum products to produce ethylene feedstock.

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