A method for the preparation of a transition metal phosphide catalyst

Abstract

The present application relates to a kind of preparation method of transition metal phosphide catalyst, including carrier preparation process and active metal solution impregnation process, including two modifications, the first modification is at least one way of modification from alkali metal modification, alkali earth metal modification, acid modification to the molecular sieve used as carrier raw material is modified to obtain modified molecular sieve, the second modification is in active metal impregnation liquid and is modified by adding polyhydroxy compound, the mass ratio of the polyhydroxy compound and the carrier is 1-15:100, preferably 3-10:100.The preparation method of transition metal phosphide catalyst provided by the present application, the catalyst prepared has higher hydrogenation isomerization performance, can produce low freezing point and low pour point lubricating oil base oil, can overcome the problem of insufficient ability of reducing freezing point and pour point of transition metal phosphide catalyst in prior art.

Description

Technical Field

[0001] This invention belongs to the field of transition metal phosphides, and particularly relates to a method for preparing a metal phosphide catalyst. Background Technology

[0002] Transition metal phosphides possess both metallic and semiconductor properties, and due to their unique characteristics, they have wide applications in electrical, mechanical, and corrosion protection fields. Transition metal phosphides also exhibit "noble metal-like" properties, demonstrating good hydrogenation performance in the hydrogenation field. The preparation and research of metal phosphide catalysts has become one of the important directions in this field. Phosphorus can form metal phosphides with various metals, resulting in a variety of compositions. Different phosphorus-to-metal ratios are collectively referred to as binary or multi-component compounds formed by transition metals and phosphorus, ranging from M3P to MP3. Transition metals that have been extensively studied include nickel, molybdenum, tungsten, cobalt, iron, and manganese.

[0003] Currently, the main methods for preparing metal phosphide catalysts include elemental synthesis, solid-state metathesis, phosphine reaction, organometallic decomposition, electrolytic molten salt, and phosphate reduction.

[0004] CN102989492A discloses a supported composite sulfur-phosphorus hydrogenation catalyst, which is composed of active metals Ni, Co or Mo, W and modified porous support materials. The active metals exist in the form of MP, MPS or MS and are supported on the porous support materials. The total amount of active metals accounts for 10-40% of the catalyst weight. The porous support materials are molecular sieves or oxides and their binary or multi-component composites. The preparation steps are as follows: (1) Dissolve soluble transition metal salts and soluble bases in water respectively, mix them, stir, precipitate, filter the obtained precipitate, wash it with deionized water, place the obtained filter cake in deionized water, stir and add H3PO2 or H3PO2 solution dropwise until the precipitate is completely dissolved. The above solution is prepared by adding a complexing agent and a transition metal salt to form a clear solution; or by dissolving the transition metal salt, phosphorus source, and complexing agent in water to form a clear solution; or by dissolving the transition metal salt, ammonium phosphomolybdate or ammonium phosphotungstenate, and complexing agent in water to form a clear solution; or by dissolving a hypophosphite containing Ni or Co, a transition metal salt, and a complexing agent in water to form a clear solution; (2) The prepared clear solution is added to the carrier and impregnated for 2-8 hours. Then the carrier impregnated with the active component is dried at 80-150℃ for 2-8 hours to prepare a composite phosphide catalyst precursor; the complexing agent is citric acid, ethylenediaminetetraacetic acid or its ammonium salt, cyclohexanediaminetetraacetic acid or its ammonium salt, tartaric acid, malic acid, ethylenediamine or ethylene glycol. The phosphorus source is phosphoric acid, hypophosphite, diammonium hydrogen phosphate, dimethylphosphite or triphenylphosphine. The transition metal salt is ammonium molybdate, ammonium tungstate, ammonium phosphomolybdate, ammonium phosphotungstate, nickel nitrate, cobalt nitrate, basic nickel carbonate, basic cobalt carbonate, or their binary or multi-component mixtures. The support is SiO2, Al2O3, HZSM-5, HY, NaY zeolite, β-molecular sieve, MCM-41, SBA-15, or a silicon-aluminum composite support, or a binary or multi-component composite oxide support. The catalyst is used in the hydrotreating reactions of gasoline, diesel, lubricating oil, and residual oil.

[0005] CN110498424A discloses a method for modifying Y molecular sieves. The method involves contacting the obtained NH4Y molecular sieve with a salt solution containing alkali metal ions and / or a salt solution containing alkaline earth metal ions. After filtration, washing, and drying, the resulting product is contacted with an acid solution, and the product is recovered to obtain the modified Y molecular sieve. The alkali metal is selected from rubidium and cesium, and the alkaline earth metal is selected from strontium and barium. The acid solution is one or more of oxalic acid, citric acid, ethylenediaminetetraacetic acid, tartaric acid, hydrochloric acid, and sulfuric acid. By screening suitable alkali metal (or alkaline earth metal) ions and using an ion exchange method, the cation distribution of the Y molecular sieve is made to exhibit an internal NH4+ distribution. +The outer molecular sieve is characterized by alkali metal (or alkaline earth metal) ions. Utilizing the stabilizing effect of these ions on the framework, the outer molecular sieve is protected during dealumination, thus preferentially dealuminizing the inner molecular sieve. By altering the type and exchange conditions of the alkali metal (or alkaline earth metal) ions, their exchange positions and amounts can be changed, thereby regulating the internal and external aluminum atom distribution and acidic site distribution of the dealuminized Y molecular sieve.

[0006] CN113578674A describes a method of contacting ZSM-5 molecular sieves with compounds of alkali and alkaline earth metals, followed by acid treatment with an acid solution, which can improve the pore structure and acidity of the ZSM-5 molecular sieves.

[0007] CN105344368A discloses a method for preparing transition metal phosphides for hydrodechlorination reactions, comprising the following steps: Step 1, dissolving a soluble metal salt and diammonium hydrogen phosphate in water, and dissolving polyethylene glycol in the above solution; Step 2, stirring the aqueous solution obtained in Step 1 at 80°C for 3 hours, then heating to 100°C to evaporate to dryness, then drying at 120°C for 12 hours, and then calcining at 500°C for 5 hours to obtain an oxidation precursor; Step 3, grinding and pressing the oxidation precursor obtained in Step 2, sieving to obtain 20-40 mesh granular material, and reducing this granular material by a programmed temperature reduction method to obtain modified transition metal phosphides.

[0008] CN108246341A discloses a method for preparing a hydrodearomatization catalyst, comprising the following steps:

[0009] (1) Under stirring conditions at room temperature, ammonium dihydrogen phosphate was dissolved in deionized water. After dissolution, nickel nitrate was added, and stirring was continued for 30 minutes. Ethylene glycol was then added and stirring was continued for 1 hour. Subsequently, a nitric acid solution with a mass concentration of 65%–68% was added dropwise to adjust the pH of the solution to the range of 2–5. Stirring was continued for at least 30 minutes. The solution was then impregnated into the carrier using the initial wet impregnation method. The sample was then dried at 80°C for at least 5 hours, and then the temperature was raised to 120°C until it was completely dry. The sample was then placed in a muffle furnace and calcined at 500°C for 2 hours to obtain the precursor. The molar ratio of ammonium dihydrogen phosphate to nickel nitrate was 0.5–2. (2) (2) Place the precursor in a tube furnace and heat it to 650°C and hold it for at least 1 hour in a flowing hydrogen atmosphere; then cool it to room temperature and then switch to 1% O2 / N2 passivation gas to passivate it at room temperature for at least 2 hours to obtain sample A; wherein the volume hourly space velocity of hydrogen is 3000-5000 h-1; (3) Using trimethylaluminum as the aluminum source, aluminum hydroxide is deposited on the surface of sample A at 150-180°C using atomic layer deposition method, and then the obtained product is placed in a tube furnace and calcined at 600°C for at least 2 hours in an argon atmosphere to obtain the desired hydrodearomatization catalyst; wherein the number of aluminum hydroxide deposition layers is 3-10 atomic layers.

[0010] The above method was used to load metal phosphides onto shape-selective molecular sieves to prepare metal phosphide catalysts. When vacuum-pressed wax oil was used as a raw material to produce lubricating oil base oil, the pour point and cloud point properties of the base oil products did not meet the requirements for use. This indicates that the hydroisomerization performance of the metal phosphide catalysts prepared by the existing technology is low and cannot meet the requirements for producing lubricating oil base oil. Therefore, to improve the hydroisomerization performance of metal phosphide catalysts on real oil products, it is necessary to improve the existing preparation method to enhance the hydroisomerization performance of the metal catalysts. Summary of the Invention

[0011] Based on the above, the main objective of this invention is to provide a method for preparing a transition metal phosphide catalyst, which can further improve the hydroisomerization performance of the metal phosphide catalyst, so as to produce lubricating oil base oil with low pour point and low pour point, and overcome the problem that the transition metal phosphide catalyst in the prior art has insufficient ability to reduce pour point and pour point.

[0012] Therefore, the present invention provides a method for preparing a transition metal phosphide catalyst, comprising a support preparation process and an active solution impregnation process, including two modifications. The first modification involves modifying the molecular sieve used as the support raw material by at least one of alkali metal modification, alkaline earth metal modification, and acid modification to obtain a modified molecular sieve. The second modification involves adding a polyhydroxy compound to the active impregnation solution for modification. The mass ratio of the polyhydroxy compound to the support is 1 to 15:100, preferably 3 to 10:100.

[0013] The method for preparing the transition metal phosphide catalyst of the present invention preferably includes a polyhydroxy compound selected from one or more of glycerol, ethylenediaminetetraacetic acid, citric acid, tartaric acid, and OH-(CH2)n-CH2-OH, wherein n is greater than or equal to 1; more preferably, OH-(CH2)n-CH2-OH is ethylene glycol and / or polyethylene glycol.

[0014] The method for preparing the transition metal phosphide catalyst of the present invention preferably includes a molecular sieve having a ten-membered or twelve-membered ring structure and a straight-through channel structure; more preferably, the molecular sieve is selected from at least one of SAPO-31, SAPO-11, ZSM-22, MCM-22, SAPO-41, ZSM-23, ZSM-35 and ZSM-48; even more preferably, the Si / Al2O3 molar ratio in the molecular sieve is 5 to 100, and the average grain size is 40 to 200 nm.

[0015] The method for preparing the transition metal phosphide catalyst of the present invention preferably includes a support further comprising alumina and / or amorphous silica-alumina material; more preferably, the content of modified molecular sieve in the support is 40-90 wt%, and the content of alumina and / or amorphous silica-alumina is 10-60 wt%.

[0016] The method for preparing the transition metal phosphide catalyst of the present invention preferably includes a modified molecular sieve having a Brønsted acid content of 0.1–0.6 mmol / g at 150°C and a Brønsted acid to Lewis acid ratio of 1:2–5:1; and a Brønsted acid content of 0.05–0.4 mmol / g at 350°C and a Brønsted acid to Lewis acid ratio of 1:2–5:1; wherein the total acid content of Brønsted acid and Lewis acid at 150°C is greater than the total acid content of Brønsted acid and Lewis acid at 350°C.

[0017] The preferred method for preparing the transition metal phosphide catalyst of the present invention involves the following preparation process of the active impregnation solution:

[0018] (1) Dissolve the phosphorus-containing component in deionized water to obtain solution A; preferably, the phosphorus-containing component is a phosphorus-containing acid or a phosphorus-containing salt, selected from one or more of phosphates, phosphoric acid, monohydrogen phosphate, dihydrogen phosphate, and hypophosphite;

[0019] (2) Dissolve the salt containing the metal component in ammonia or deionized water to obtain solution B;

[0020] (3) Add solution B to solution A to obtain mixed solution C;

[0021] (4) Continue to add the solution containing polyhydroxy compounds, and heat to a constant volume to obtain the active impregnation solution.

[0022] The method for preparing the transition metal phosphide catalyst of the present invention preferably includes the following steps: impregnating an active impregnation solution onto a support, homogenizing at 20-40°C, drying at 60-120°C, and then reducing it at 300-500°C under a hydrogen atmosphere to obtain the metal phosphide catalyst.

[0023] In the preparation method of the transition metal phosphide catalyst of the present invention, it is preferred that, in the first modification process, the total mass ratio of alkali metal, alkaline earth metal and / or acid to molecular sieve is 0.2 to 100:1000, more preferably 0.3 to 50:1000.

[0024] The method for preparing the transition metal phosphide catalyst of the present invention preferably includes the following: the alkali metal is a Group IA metal, the alkaline earth metal is a Group IIA metal, and the acid is selected from at least one of nitric acid, phosphoric acid, phosphorous acid, hypophosphorous acid, acetic acid, tartaric acid, oxalic acid, citric acid, and malic acid.

[0025] The method for preparing the transition metal phosphide catalyst of the present invention preferably includes a method in which the active metal component in the active impregnation solution is selected from at least one of cobalt, nickel, molybdenum, and tungsten, and more preferably nickel; the active component in the catalyst accounts for 10-30% of the catalyst mass based on the sum of the weight of the metal component (based on the weight of the metal element) and the phosphorus element, and the metal component is based on the weight of the metal element.

[0026] In the method for preparing the transition metal phosphide catalyst of the present invention, preferably, the salt containing the metal active component in step (2) is selected from one or more of nitrates, carbonates, basic carbonates, and sulfates.

[0027] In the method for preparing the transition metal phosphide catalyst of the present invention, preferably, the molar ratio of phosphorus element (based on elemental composition) to metal component (based on elemental composition) in the catalyst is 1:5 to 5:1.

[0028] Specifically, the preparation method of the transition metal phosphide catalyst provided by this invention includes the following steps:

[0029] Step 1: The molecular sieve is modified for the first time by using alkali metal salts, alkaline earth metals and / or acids, followed by drying and calcination to obtain the modified molecular sieve.

[0030] Step 2: Mix the modified molecular sieve with alumina and / or amorphous silica-alumina, and extrude it to obtain a catalyst support;

[0031] Step 3: Dissolve the phosphorus-containing acid or phosphorus-containing salt in deionized water to obtain solution A;

[0032] Step 4: Dissolve the salt containing the metal component in ammonia or deionized water to obtain solution B;

[0033] Step 5: Slowly add solution B from step 4 to solution A from step 3 to obtain mixed solution C;

[0034] Step 6: Add the solution containing the polyhydroxy compound to the mixed solution C from step 5, and heat to a constant volume to obtain the active impregnation solution D;

[0035] Step 7: Slowly add the active impregnation solution D from step 6 to the support obtained in step 2, then homogenize at 20–40°C, dry at 60–120°C, and then reduce at 300–500°C under a hydrogen atmosphere to obtain the metal phosphide catalyst.

[0036] The beneficial effects of this invention are as follows:

[0037] The method for preparing transition metal phosphide catalysts provided by this invention produces catalysts with high hydroisomerization performance, capable of producing lubricating oil base oils with low pour point and low freezing point, thus overcoming the problem of insufficient ability of existing transition metal phosphide catalysts to lower pour point and freezing point. Detailed Implementation

[0038] 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, and percentages not specified are by weight.

[0039] The method for preparing transition metal phosphide catalysts provided by this invention involves three major steps: preparation of the support, preparation of the impregnation solution, and metal impregnation.

[0040] Catalyst support preparation: The molecular sieve used needs to be modified with alkali metal salts, alkaline earth metal salts and / or acids. The modified molecular sieve is then dried and calcined. In the preparation of the catalyst support, the modified molecular sieve is mixed with alumina and / or amorphous silica-alumina and extruded to obtain the catalyst support.

[0041] Preparation of impregnation solution: (1) In the preparation of impregnation solution, add phosphorus-containing acid or phosphorus-containing salt to deionized water to dissolve and obtain solution A; (2) Add one or more of the metal active components to ammonia or deionized water to dissolve and obtain solution B; (3) Slowly add solution B to solution A to obtain mixed solution C; then add the solution containing polyhydroxy organic matter to step 5, heat to a constant volume to obtain impregnation solution D;

[0042] Metal impregnation: Impregnation solution D is slowly added to the obtained catalyst support, then homogenized at 20-40°C, dried at 60-80°C, and then reduced at 300-500°C under a hydrogen atmosphere to obtain a metal phosphide catalyst.

[0043] The polyhydroxy compound is selected from one or more of glycerol, ethylenediaminetetraacetic acid, citric acid, tartaric acid, and OH-(CH2)n-CH2-OH, wherein n is greater than or equal to 1; preferably, OH-(CH2)n-CH2-OH is ethylene glycol and / or polyethylene glycol.

[0044] The active metal component is one or more of cobalt, nickel, molybdenum, and tungsten, and the phosphorus element is selected from one or more of phosphate, phosphoric acid, monohydrogen phosphate, dihydrogen phosphate, and hypophosphite.

[0045] The modified molecular sieve is obtained by modifying a molecular sieve with alkali metal, alkaline earth metal, and / or acid modifying agents. The molecular sieve has a ten-membered or twelve-membered ring structure. It should be noted that the molecular sieve is one or more of SAPO-11, ZSM-22, MCM-22, ZSM-23, ZSM-35, and ZSM-48, i.e., selected from molecular sieves with ten-membered or twelve-membered ring structures. Experiments show that molecular sieves with ten-membered or twelve-membered ring structures exhibit good catalytic performance in the field of hydroisomerization, and these molecular sieves have a through-pore structure. In another embodiment, the Si / Al2O3 molar ratio in the molecular sieve is 5–100, and the average grain size is 40–200 nm.

[0046] In this embodiment, the molecular sieve is modified by using alkali metal salts, alkaline earth metals, and / or acid modifying agents. The modification can be performed by impregnation; specifically, an alkali metal and / or alkaline earth metal compound can be dissolved in deionized water to form a uniform modified impregnation solution, and the molecular sieve can be impregnated in the modified impregnation solution to obtain the modified molecular sieve. For acid modification, specifically, an acid can be dissolved in deionized water to form a uniform modified impregnation solution, and the molecular sieve can be impregnated in the modified impregnation solution to obtain the modified molecular sieve. The molecular sieve can be impregnated by mixing the impregnation solutions, or the molecular sieve can be impregnated separately in impregnation solutions formed by alkali metal compounds, alkaline earth metals, and acids. This application does not limit the order of impregnation of alkali metals, alkaline earth metals, and acids. For example, it can be impregnated first in alkali metal impregnation solution and / or alkaline earth metal impregnation solution, and then in acid impregnation solution; it can also be impregnated first in acid impregnation solution, and then in alkali metal and / or alkaline earth metal impregnation solution; it can also be impregnated alone in alkali metal compound; it can also be impregnated alone in alkaline earth metal compound; it can also be impregnated alone in acid compound impregnation solution.

[0047] In one embodiment, the alkali metal salt and alkaline earth metal are selected from one or more Group IA and Group IIA metals, such as lithium, sodium, potassium, rubidium, cesium, francium, beryllium, magnesium, calcium, strontium, barium, radium, etc. The alkali / alkaline earth metal salt compound is a soluble alkali / alkaline earth metal salt, such as nitrate-containing alkali metal salts, sulfate-containing alkali metal salts, and chloride-containing alkali metal salts. The acidic compound can be one or more of nitric acid, phosphoric acid, acetic acid, tartaric acid, hydrochloric acid, and citric acid.

[0048] In another embodiment, the concentration of the alkali / alkaline earth metal salt compound in the impregnation solution is 0.1–0.3 mol / L; the concentration of the acid in the impregnation solution is 0.1–0.3 mol / L. During the impregnation process, the volume of acid impregnation solution or alkali metal salt compound impregnation solution used per 100 g of molecular sieve is 60–100 ml. Modifying the molecular sieve with acidic or alkali metal compounds can effectively improve the pore structure, specific surface area, and acidity distribution of the support, thereby improving the catalytic performance of the catalyst.

[0049] The aforementioned molecular sieve was modified with alkali / alkaline earth metal salts and / or acids to obtain modified molecular sieves. The modified molecular sieves were characterized using pyridine infrared spectroscopy. At 150℃, the Brønsted acid (B acid) content was 0.1–0.5 mmol / g, with a B acid:L acid ratio of 5:1–1:1; at 350℃, the B acid content was 0.1–0.3 mmol / g, with a B acid:L acid ratio of 5:1–1:1. The total acid content at 150℃ (i.e., the acid content of B acid + L acid) was greater than that at 350℃. Thus, the transition metal phosphide catalyst prepared using this molecular sieve can be used to produce low-pour-point lubricating oil base oils. The produced base oils possess the advantages of both low pour point and low cloud point, as well as high liquid yield and low aromatic content.

[0050] In one embodiment, the catalyst support of the present invention further includes alumina and / or amorphous silica-alumina, thus forming a composite support with the modified molecular sieve and alumina and / or amorphous silica-alumina. The metallic active component of the catalyst of the present invention can be a transition metal element, such as one or more of nickel, molybdenum, tungsten, cobalt, iron, and zirconium; phosphorus is selected from one or more of phosphates, phosphoric acid, monohydrogen phosphate, dihydrogen phosphate, and hypophosphite. In another embodiment, based on the total mass of the catalyst, the support content in the catalyst is 60-90%, and the combined content of the metallic active component and phosphorus is 10-40%. More specifically, the molecular sieve content in the support is, for example, 40-90%, and the alumina or alumina and amorphous silica-alumina content in the support is, for example, 10-60%.

[0051] The types of molecular sieves and modification methods have been described in detail above, and will not be repeated here.

[0052] The technical solution of the present invention will be further described below through specific embodiments.

[0053] Example 1

[0054] In this embodiment, ZSM-22, SAPO-11, MCM-22, ZSM-23, ZSM-35 and ZSM-48 are commercially available or prepared by any existing method, preferably with a Si / Al2O3 molar ratio of 5 to 100 and an average grain size of 30 to 150 nm. Molecular sieves are modified with alkali metal solutions or acidic solutions. The alkali metals are selected from Group IA or IIA metals, and the acids are selected from one or more of nitric acid, phosphoric acid, acetic acid, tartaric acid, hydrochloric acid, and citric acid. The modification process involves impregnating the molecular sieve with a modified auxiliary agent, a Group IA or IIA metal salt solution, or the above-mentioned acid solution at a concentration controlled at 0.1–0.3 mol / L. The ratio of molecular sieve mass (in g) to impregnation liquid volume (in ml) is 100:60–100. Taking 100 g of molecular sieve raw powder as an example, samples A1, B1, C1, D1, E1, and F1 are molecular sieve raw powders that have not undergone modification treatment. The SiO2 / Al2O3 molar ratio, average grain size, and modified reagents and their amounts for the molecular sieves are shown in Table 1.

[0055] Table 1. Properties of Molecular Sieves and Modifying Reagents

[0056]

[0057]

[0058] The modified molecular sieves in Table 1 were dried at 120℃ for 2 hours and calcined at 500℃ for 4 hours, and were used for pyridine infrared (Py-IR) characterization and preparation of metal phosphide catalysts.

[0059] After vacuum pretreatment in the pyridine sample cell, the sample was saturated with adsorption in the pyridine sample cell in a 0℃ ice bath. Then, pyridine desorption characterization was performed at 150℃ and 350℃. The amounts of Brønsted acid and Lewis acid in the sample at the two desorption temperatures of 150℃ and 350℃ were calculated. The characterization results are shown in Table 2.

[0060] Table 2. Py-IR characterization results of molecular sieves

[0061]

[0062] Example 2

[0063] Take 35g (dry basis weight) of the modified A2 sample from Example 1, namely SAPO-11 molecular sieve, mix it with 30g of alumina powder (dry basis weight) and 15g of amorphous silica-alumina powder (dry basis weight, silica content is 30%), form it by extrusion machine, and prepare the carrier by drying the wet strip at 120℃ for 3 hours and calcining at 550℃ for 4 hours.

[0064] The catalyst contains molybdenum (Mo) and phosphorus (P) in a molar ratio of 1:1, with a total elemental loading of 20% for both molybdenum and phosphorus. Ammonium molybdate ((NH4)6Mo7O) is used. 24 Dissolve 27.86g of diammonium hydrogen phosphate ((NH4)2HPO4) and 20.94g of diammonium hydrogen phosphate in 100ml of 3mol / L ammonia water to obtain solution A. Dissolve 8g of ethylene glycol in 20ml of deionized water to obtain solution B. Slowly add solution B dropwise to solution A to obtain mixed solution C. Heat mixed solution C to make up to 80ml to obtain solution D, which is ready for use.

[0065] Solution D was impregnated onto the catalyst support and impregnated at 30°C for 4 hours, and then dried at 60°C for 4 hours to obtain catalyst precursor A.

[0066] Example 3

[0067] Take 80g (dry basis weight) of the modified B2 sample from Example 1, namely ZSM-22 molecular sieve, mix it with 6g of alumina powder (dry basis weight) and 4g of amorphous silica-alumina powder (dry basis weight, silica content is 50%), form it by extrusion machine, and prepare the carrier by drying the wet strip at 150℃ for 2 hours and calcining at 500℃ for 6 hours.

[0068] In the catalyst, tungsten (W) and phosphorus (P) are in a molar ratio of 1:1, with a total elemental loading of 10% for both tungsten and phosphorus. Ammonium metatungstate ((NH4)6W) is used. 12 O 39 Dissolve 11.54g of 2H2O and 5.37g of ammonium dihydrogen phosphate (NH4H2PO4) in 100ml of deionized water to obtain solution A. Dissolve 3g of ethylenediaminetetraacetic acid in 20ml of deionized water to obtain solution B. Slowly add solution B dropwise to solution A to obtain solution C. Heat solution C to bring the volume to 70ml to obtain solution D, which is ready for use.

[0069] Solution D was impregnated onto the catalyst support and impregnated at 25°C (room temperature) for 4 hours, and then dried at 120°C for 6 hours to obtain catalyst precursor B.

[0070] Example 4

[0071] The modified C2 and D2 samples from Example 1, namely 15g of MCM-22 molecular sieve (dry basis weight) and 27g of ZSM-48 molecular sieve (dry basis weight), were mixed with 20g of alumina powder (dry basis weight) and 8g of amorphous silica-alumina powder (dry basis weight, silica content of 50%), formed by extrusion, and the wet strips were dried at 120℃ for 4 hours and calcined at 500℃ for 6 hours to prepare a carrier.

[0072] The catalyst contains nickel (Ni) and phosphorus (P) in a molar ratio of 2:1, with a total nickel and phosphorus loading of 30%. 118g of nickel nitrate (Ni(NO3)2·6H2O) and 23.6g of ammonium hypophosphite ((NH4)2HPO3) were dissolved in 250ml of deionized water to obtain solution A. 7g of polyethylene glycol was added to 30ml of deionized water to obtain solution B. Solution B was slowly added dropwise to solution A to obtain solution C. Solution C was heated to a final volume of 70ml to obtain solution D. Solution D was then heated to a final volume of 200ml for later use.

[0073] The solution was impregnated onto the catalyst support twice, 100 ml each time. After each impregnation, the solution was impregnated at 25°C for 4 h, and then dried at 120°C for 3 h to obtain the catalyst precursor C.

[0074] Comparative Example 1

[0075] The difference from Example 4 is that unmodified C1 and D1 samples were taken, and the remaining steps were the same as in Example 4, to obtain the catalyst precursor as DC.

[0076] Example 5

[0077] The modified E2 sample from Example 1, namely 35g of ZSM-35 molecular sieve (dry basis weight), 35g of alumina powder (dry basis weight), and 15g of amorphous silica-alumina powder (dry basis weight, silica content 50%), was mixed and kneaded, formed by an extruder, and the wet strip was dried at 120℃ for 4 hours and calcined at 500℃ for 6 hours to prepare a carrier.

[0078] The catalyst contains nickel (Ni) and phosphorus (P) in a molar ratio of 1:5, with a total nickel and phosphorus elemental loading of 15%. 20.4 g of nickel nitrate (Ni(NO3)2·6H2O) and 40.8 g of ammonium hypophosphite ((NH4)2HPO3) were dissolved in 150 ml of deionized water to obtain solution A. 8.5 g of citric acid was added to 40 ml of deionized water to obtain solution B. Solution B was slowly added dropwise to solution A to obtain solution C. Solution C was heated to a final volume of 80 ml to obtain solution D, which was then set aside.

[0079] Solution D was impregnated onto the catalyst support. After each impregnation, the solution was impregnated at 40°C for 4 hours and then dried at 100°C for 3 hours to obtain the catalyst precursor D.

[0080] Example 6

[0081] The difference from Example 5 is that the nickel (Ni) and phosphorus (P) in the catalyst are in a molar ratio of 5:1, the total loading of nickel and phosphorus elements is 15%, 67.7g of nickel nitrate (Ni(NO3)2·6H2O) and 5.4g of ammonium hypophosphite ((NH4)2HPO3) are used, and the rest of the steps are the same, finally obtaining catalyst precursor E.

[0082] Comparative Example 2

[0083] Similar to Example 6, the step of adding 8.5g of citric acid to 40ml of deionized water is omitted in the preparation of the impregnation solution. The remaining steps are the same as in Example 6, and the catalyst precursor obtained is DE.

[0084] Example 7

[0085] The difference from Example 6 is that the nickel (Ni) and phosphorus (P) in the catalyst are in a molar ratio of 1:5, and the total loading of nickel and phosphorus elements is 15%. 20.4g of nickel nitrate (Ni(NO3)2·6H2O) and 13.6g of ammonium hypophosphite ((NH4)2HPO3) are dissolved in 150ml of deionized water. 8.5g of citric acid is converted into 8.5g of tartaric acid. The remaining steps are the same, and finally the catalyst precursor F is obtained.

[0086] Example 8

[0087] Take 50g (dry basis weight) of the modified F2 sample from Example 1, namely ZSM-23 molecular sieve, mix it with 20g of alumina powder (dry basis weight) and 15g of amorphous silica-alumina powder (dry basis weight, silica content is 50%), form it by extrusion machine, and prepare the carrier by drying the wet strip at 150℃ for 2 hours and calcining at 500℃ for 6 hours.

[0088] The catalyst contains nickel (Ni) and phosphorus (P) in a molar ratio of 3:1, with a total nickel and phosphorus elemental loading of 15%. 42.78 g of nickel nitrate (Ni(NO3)2·6H2O) and 8.5 g of ammonium hypophosphite ((NH4)2HPO3) were dissolved in 150 ml of deionized water to obtain solution A. 8.5 g of ethylene glycol was added to 40 ml of deionized water to obtain solution B. Solution B was slowly added dropwise to solution A to obtain solution C. Solution C was heated to a final volume of 85 ml to obtain solution D, which was then set aside.

[0089] The solution D was impregnated onto the catalyst support. After each impregnation, the catalyst was impregnated at 25°C for 4 hours, and then dried at 100°C for 2 hours to obtain the catalyst precursor G.

[0090] Comparative Example 3

[0091] Similar to Example 8, the unmodified G1 sample was used, and the step of adding 8.5g of ethylene glycol to 40ml of deionized water was omitted in the preparation of the impregnation solution. The remaining steps were the same as in Example 8, and the catalyst precursor was DG.

[0092] Example 9

[0093] The catalyst precursors obtained in Examples 2 to 8 and Comparative Examples 1 to 3 were each 100 ml and loaded into a fixed-bed reactor. Under a hydrogen atmosphere, with a hydrogen pressure of 2 MPa and a hydrogen flow rate of 50 L / h, the reactor was kept at 450°C for 6 h. Then, the temperature was lowered to 60°C and nitrogen was switched to purge. The reactor was purged for 4 h at the same pressure and gas flow rate to obtain catalysts A-cat, B-cat, C-cat, D-cat, E-cat, F-cat, G-cat, DC-cat, DE-cat, and DG-cat.

[0094] Example 10

[0095] The catalysts prepared in Example 9 were selected for hydrogenation evaluation. Six catalysts, namely C-cat, E-cat, G-cat, DC-cat, DE-cat, and DG-cat, were selected for hydrogenation performance evaluation. A fixed-bed reactor was used, and the catalyst loading volume was 100 ml. The hydrogenation evaluation process conditions are shown in Table 3. The feedstock oil used for evaluation was hydrogenated vacuum wax oil, and its properties are shown in Table 4.

[0096] Table 3 Hydrogenation Evaluation Process Conditions

[0097] Reaction temperature, °C 375 Hydrogen partial pressure, MPa 13 <![CDATA[Liquid hourly space velocity, h -1 > 1.2 Hydrogen-to-oil volume ratio 500

[0098] Table 4 Properties of Crude Oil

[0099]

[0100]

[0101] The full-fraction lubricating oil base oil products generated after hydrotreating were cut by a vacuum distillation tower to obtain lubricating oil base oils of different viscosity grades. The total base oil yield and the properties of the lubricating oil base oil products above 370℃ are shown in Table 5.

[0102] Table 5. Evaluation Results of Hydrogenation

[0103]

[0104] The catalyst prepared by the method of this invention can produce lubricating oil base oil with low pour point, low freezing point, and low aromatics in the production of lubricating oil base oil using vacuum wax oil as raw material, compared with the catalyst not prepared by the method of this invention. At the same time, the lubricating oil base oil yield is high and the viscosity index loss is small.

[0105] In the catalyst preparation of this invention, the support material is selected from one or more of SAPO-11, ZSM-22, MCM-22, ZSM-23, ZSM-35, and ZSM-48. The molecular sieve material is modified with alkali metal salts and / or acids. The modified molecular sieve is characterized by pyridine infrared spectroscopy. At 150℃, the Brønsted acid content is 0.1–0.5 mmol / g, and the ratio of Brønsted acid to Lewis acid is 5:1–1:1; at 350℃, the Brønsted acid content is 0.1–0.3 mmol / g, and the ratio of Brønsted acid to Lewis acid is 5:1–1:1. The ratio of Brønsted acid to Lewis acid at 150℃ is... The total acid content is greater than the total acid content of Brønsted acid and Lewis acid at 350℃. Simultaneously, alumina and / or amorphous silica-alumina materials are introduced into the support preparation process. In the impregnation solution preparation, the salts of the metal components are dissolved with phosphorus-containing salts or acids to form a solution. A polyhydroxy organic compound is added to the solution to prepare a metal phosphide catalyst. This preparation method improves the catalyst's acid distribution, specific surface area, and pore structure, while weakening the interaction between the support and the metal, resulting in a more uniform distribution of the metal phosphide in the support. This promotes the enhancement of the catalyst's catalytic activity, leading to the preparation of base oils with low pour points and low freezing points.

[0106] 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 method for preparing a transition metal phosphide catalyst for producing low pour point and low freezing point lubricating oil base oils, comprising a support preparation process and an active solution impregnation process, characterized in that, The process includes two modifications. The first modification involves modifying the molecular sieve used as the carrier material by at least one of alkali metal modification, alkaline earth metal modification, and acid modification to obtain a modified molecular sieve. The second modification involves adding a polyhydroxy compound to a mixed solution containing metal components and phosphorus components to obtain an active impregnation solution. The active impregnation solution is impregnated onto the support, homogenized at 20–40°C, dried at 60–120°C, and then reduced at 300–500°C under a hydrogen atmosphere to obtain a transition metal phosphide catalyst. The active component in the transition metal phosphide catalyst, calculated as the sum of the weights of the metal component and phosphorus, accounts for 10-30% of the mass of the transition metal phosphide catalyst, wherein the metal component is calculated as the weight of the elemental metal, and the molar ratio of phosphorus to the metal component is 1:5-5:

1. The molecules are screened from at least one of SAPO-31, SAPO-11, ZSM-22, MCM-22, SAPO-41, ZSM-23, ZSM-35 and ZSM-48; In the first modification process, the ratio of the total mass of alkali metals, alkaline earth metals and / or acids to the mass of molecular sieve is 0.3~50:1000. The mass ratio of the polyhydroxy compound to the support is 1~15:100; The polyhydroxy compound is selected from one or more of glycerol, ethylenediaminetetraacetic acid, citric acid, tartaric acid, and OH-(CH2)n-CH2-OH, wherein n is greater than or equal to 1; The modified molecular sieve has the following characteristics: at 150℃, the Brønsted acid content is 0.1~0.6 mmol / g, and the ratio of Brønsted acid to Lewis acid is 1:2~5:1; at 350℃, the Brønsted acid content is 0.05~0.4 mmol / g, and the ratio of Brønsted acid to Lewis acid is 1:2~5:1; wherein the total acid content of Brønsted acid and Lewis acid at 150℃ is greater than the total acid content of Brønsted acid and Lewis acid at 350℃.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the polyhydroxy compound to the support is 3~10:

100.

3. The preparation method according to claim 1, characterized in that, The OH-(CH2)n-CH2-OH is ethylene glycol and / or polyethylene glycol.

4. The preparation method according to claim 1, characterized in that, The molecular sieve has a Si / Al2O3 molar ratio of 5 to 100 and an average grain size of 40 to 200 nm.

5. The preparation method according to claim 1, characterized in that, The carrier also includes alumina and / or amorphous aluminum silicate materials.

6. The preparation method according to claim 5, characterized in that, The modified molecular sieve content in the carrier is 40-90 wt%, and the content of alumina and / or amorphous silica-alumina material is 10-60 wt%.

7. The preparation method according to claim 1, characterized in that, The preparation process of the active impregnation solution is as follows: (1) Dissolve the phosphorus-containing component in deionized water to obtain solution A; (2) Dissolve the salt containing the metal component in ammonia or deionized water to obtain solution B; (3) Add solution B to solution A to obtain mixed solution C; (4) Continue to add the solution containing polyhydroxy compounds, and heat to a constant volume to obtain the active impregnation solution.

8. The preparation method according to claim 7, characterized in that, The phosphorus-containing component is selected from one or more of phosphates and phosphoric acid.

9. The preparation method according to claim 7, characterized in that, The phosphorus-containing component is selected from one or more of monohydrogen phosphate, dihydrogen phosphate, and hypophosphite.

10. The preparation method according to claim 1, characterized in that, The alkali metal is a Group IA metal, the alkaline earth metal is a Group IIA metal, and the acid is selected from at least one of nitric acid, phosphoric acid, phosphorous acid, hypophosphoric acid, acetic acid, tartaric acid, oxalic acid, citric acid, and malic acid.

11. The preparation method according to claim 1, characterized in that, The metal component in the active impregnation solution is selected from at least one of cobalt, nickel, molybdenum, and tungsten.

12. The preparation method according to claim 11, characterized in that, The metal component in the active impregnation solution is nickel.

13. The preparation method according to claim 7, characterized in that, In step (2), the salt containing the metal component is selected from one or more of the following: nitrates, carbonates, basic carbonates, and sulfates.

Images