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 salt modification, alkali earth metal salt modification, acid modification to the molecular sieve used as carrier raw material is modified, and modified molecular sieve is obtained, the second modification is at least one of alkali metal salt, alkali earth metal salt and acid is added in active metal impregnation solution and is modified.The catalyst obtained by the preparation method can be used as raw material of vacuum gas oil, and low condensation point, low pour point lubricating oil base oil can be produced.The base oil produced has low aromatic content, the catalyst has strong isomerization performance, outstanding aromatic saturation performance, and less viscosity index loss.The qualified lubricating oil base oil can be produced without adding additional refining catalyst and process.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of transition metal phosphides, and particularly relates to a transition metal phosphide catalyst. BACKGROUND

[0002] Metal phosphides are binary or multi-component compounds formed by transition metals and phosphorus, wherein the transition metals include nickel, molybdenum, tungsten, cobalt, iron, manganese, zirconium, vanadium, niobium, uranium, thorium, plutonium and yttrium. Phosphorus and transition metals can form both metallic bonds and covalent bonds, so that transition metal phosphides (hereinafter referred to as metal phosphides) can be both ionic, covalent or metallic, and covalent compounds, which have the characteristics of covalent solids, ionic crystals and transition metals, thus showing special physical and chemical properties and good application prospects in the fields of photoelectricity, magnetism, catalysis and the like. Transition metal phosphides are a new type of catalytic material after carbides and nitrides, and have become a hot spot in the field of new catalytic material research due to their similar physical properties to nitrides and carbides and more excellent catalytic hydrogenation activity and sulfur resistance.

[0003] At present, the applications of transition metal phosphide catalysts mainly include important reaction processes such as hydrogenation desulfurization (HDS), hydrogenation denitrification (HDN) of gasoline and diesel oil, hydrogenation deoxygenation (HDO) of biomass fuel, hydrogenation isomerization, hydrazine decomposition, and hydrocarbon reforming to synthetic gas.

[0004] CN1492025A discloses a preparation method of a supported transition metal phosphide distillate deep hydrogenation desulfurization catalyst. The steps are as follows: dissolving a salt of a transition metal and a phosphate in water, adjusting the pH value to 2-4, under vacuum conditions, dropping the prepared solution into a carrier, impregnating for 1-10 hours, then quickly evaporating water, drying at 80-180°C for 10-14 hours, and calcining in air at 300-600°C for 1-10 hours, to obtain a supported transition metal phosphide oxidation state deep hydrogenation desulfurization catalyst. The carrier is a composite of a mesoporous molecular sieve and / or a porous oxide, wherein the mass percentage content of the mesoporous molecular sieve is 0-100%, and the mass percentage content of the porous oxide is 0-100%. The mesoporous molecular sieve is MCM-41 or SBA-15 / 16, and the porous oxide is Y zeolite molecular sieve, ZSM-5 zeolite molecular sieve, mordenite molecular sieve, β zeolite molecular sieve, A type zeolite molecular sieve, X type zeolite molecular sieve, MCM-22 molecular sieve, AlPO4 type molecular sieve, alumina, silica, titania, zirconia or a binary or multi-component composite thereof. The transition metal is Ni, Mo, Co, Mo, W, Fe, Mn, Pt, Pd, Ru or a binary or multi-component composite thereof. The present technical disclosure is different from the comparative document 1 in that it does not mention modification of the molecular sieve and modification of the active metal.

[0005] CN110498424A discloses a Y molecular sieve modification method, the obtained NH4Y molecular sieve is contacted with a salt solution containing alkali metal ions and / or a salt solution containing alkaline earth metal ions, after filtration, washing and drying, the obtained product is contacted with an acid solution, and the product is recovered to obtain a modified Y molecular sieve; wherein the alkali metal is selected from rubidium, cesium, the alkaline earth metal is selected from strontium, barium, and 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, ion exchange method is adopted, so that the cation distribution of Y molecular sieve presents the characteristics that the inside is NH4 + , the outside is alkali metal (or alkaline earth metal) ion, the effect of stabilizing the framework by alkali metal (or alkaline earth metal) ion is utilized to protect the outer molecular sieve in dealuminization, so that the inner molecular sieve is preferentially dealuminated. By changing the type, exchange condition and other factors of alkali metal (or alkaline earth metal) ion, the exchange position and exchange amount of alkali metal (or alkaline earth metal) ion can be changed, and then the distribution of internal and external aluminum atoms and the distribution of acid sites of dealuminated Y molecular sieve can be adjusted.

[0006] CN113578674A discloses an automatic dispensing system and dispensing method, ZSM-5 molecular sieve is contacted with alkali and alkaline earth metal compounds; then acid solution is used for acid treatment, which can improve the pore structure and acidity of ZSM-5 molecular sieve.

[0007] CN102427880A discloses a catalyst for preparing biodiesel, which comprises a metal phosphide as an active ingredient for hydroprocessing or isomerization, and the metal phosphide as the active ingredient is obtained by combining a group VIB metal, a group VIII metal, a group VIIB metal, or a mixture thereof with P, wherein the catalyst only comprises the metal phosphide, or further comprises carbon, an alkaline earth metal oxide, an alkali metal oxide, alumina, silica, silica-alumina, zirconia, titania, silicon carbide, niobium oxide, aluminum phosphate, or a mixture thereof as a carrier or a binder.

[0008] In the metal phosphide catalyst in the prior art, the transition metal phosphide is modified by metal salt, the molecular sieve is modified by alkali metal salt or acid, and the catalyst prepared by the two modification methods is used in the production of lubricating oil base oil by wax oil hydroisomerization reaction, which cannot effectively reduce the condensation point and pour point of the lubricating oil base oil. SUMMARY

[0009] Based on the above, the present application aims to provide a transition metal phosphide catalyst for better reducing the low-temperature performance of oil products, i.e. reducing the pour point performance of base oil of lubricating oil, to overcome the problem of insufficient ability of the transition metal phosphide catalyst in the prior art to reduce the freezing point and pour point.

[0010] To this end, the present application provides a preparation method of a transition metal phosphide catalyst, comprising a carrier preparation process and an active metal solution impregnation process, including two modifications, the first modification is to modify the molecular sieve used as a carrier raw material by at least one of alkali metal modification, alkaline earth metal modification, acid modification to obtain a modified molecular sieve, and the second modification is to add at least one of an alkali metal compound, an alkaline earth metal compound and an acid in the active metal impregnation solution for modification.

[0011] Specifically, the modification method can be an impregnation method, specifically, the alkali metal compound and / or the alkaline earth metal compound can be dissolved in deionized water to form a uniform modified impregnation solution, and the above-mentioned molecular sieve is impregnated in the modified impregnation solution to obtain a modified molecular sieve; the acid modification, specifically, the modification method is specifically to dissolve the acid in deionized water to form a uniform modified impregnation solution, and the above-mentioned molecular sieve is impregnated in the modified impregnation solution to obtain a modified molecular sieve. It can also be that the molecular sieve is impregnated in the impregnation solution formed by the alkali metal / alkaline earth metal compound and the impregnation solution formed by the acid. The present application does not limit the order of impregnating the alkali metal compound, the alkaline earth metal compound and the acidic compound, for example, the alkali metal compound and / or the alkaline earth metal compound can be impregnated first, and then the acid impregnation solution is impregnated; or the acid impregnation solution can be impregnated first, and then the alkali metal compound impregnation solution and / or the alkaline earth metal compound is impregnated.

[0012] Further, the alkali / alkaline earth metal compound is a soluble alkali / alkaline earth metal salt, such as an alkali metal salt containing nitrate, an alkali metal salt containing sulfate, and an alkali metal salt containing chloride. Specifically, the concentration of the alkali / alkaline earth metal in the impregnation solution formed by the alkali / alkaline earth metal compound is 0.2-0.6 mol / L; and the concentration of the acid in the impregnation solution formed by the acid is 0.2-0.6 mol / L. During the impregnation process, the volume of the acid compound impregnation solution or the alkali metal compound impregnation solution used per 100 g of the molecular sieve is 60-100 ml. The modification of the molecular sieve by the acid compound or the alkali metal compound can effectively improve the pore structure properties, the specific surface area and the acid distribution of the carrier, and further improve the catalytic performance of the catalyst.

[0013] The preparation method of the transition metal phosphide catalyst described in the present application, wherein preferably, the modified molecular sieve has a ten-membered ring or a twelve-membered ring structure, and simultaneously has a straight-through pore channel structure.

[0014] Specifically, the molecular sieve with the above structure exhibits good catalytic performance in the field of hydrogen isomerization.

[0015] The preparation method of the transition metal phosphide catalyst, wherein preferably, the carrier further comprises alumina and / or amorphous silica-alumina. The modified molecular sieve and the alumina and / or amorphous silica-alumina are thus formed into a composite carrier. Further preferably, the content of the modified molecular sieve in the carrier is 40-90wt%, and the content of the alumina and / or amorphous silica-alumina is 10-60wt%.

[0016] The preparation method of the transition metal phosphide catalyst, wherein preferably, the modified molecular sieve has a B acid content of 0.1-0.6mmol / g at 150°C, and a B acid to L acid content ratio of 1:2-5:1; has a B acid content of 0.05-0.4mmol / g at 350°C, and a B acid to L acid content ratio of 1:2-5:1; and wherein the total acid amount of the B acid and the L acid at 150°C is greater than the total acid amount of the B acid and the L acid at 350°C. Thus, the transition metal phosphide catalyst prepared from the molecular sieve is used for producing a lubricating oil base oil with a low pour point, and the produced base oil has the advantages of low freezing point and pour point, high liquid yield, and strong aromatic saturation performance, without the need for adding a supplemental refining reactor to reduce the aromatic content.

[0017] The preparation method of the transition metal phosphide catalyst, wherein 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; and further preferably, the Si / Al2O3 molar ratio of the molecular sieve is 0.1-100, and the average crystal grain size is 30-200nm.

[0018] The preparation method of the transition metal phosphide catalyst, wherein preferably, 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, acetic acid, tartaric acid, hydrochloric acid, hydrofluoric acid, citric acid, and malic acid.

[0019] The preparation method of the transition metal phosphide catalyst, wherein preferably, the metal active component in the active metal solution is a transition metal, preferably selected from at least one of nickel, molybdenum, tungsten, cobalt, iron, and zirconium, and the metal active component in the catalyst accounts for 10-40% of the mass of the catalyst, further preferably 10-30% in terms of oxides.

[0020] The preparation method of the transition metal phosphide catalyst, wherein preferably, the molar ratio of the phosphorus content to the metal active component content in the catalyst is 1:7-7:1, and more preferably 1:5-5:1. The phosphorus in the catalyst is prepared into a solution by at least one of phosphates, phosphoric acid, monohydrogen phosphate, dihydrogen phosphate, hypophosphite, and is loaded onto the carrier by impregnation.

[0021] The preparation method of the transition metal phosphide catalyst, wherein preferably, the mass ratio of the metal active component to the carrier in the catalyst is 1:10-1:1, the mass ratio of the modified molecular sieve to alumina in the carrier is 2:3-9:1, and the auxiliary agent used in the two modifications accounts for 1%-10% of the mass of the catalyst.

[0022] The preparation method of the transition metal phosphide catalyst, wherein preferably, the mass ratio of the metal active component to the carrier in the catalyst is 1:9-3:7.

[0023] The beneficial effects of the present application are as follows:

[0024] The preparation method of the transition metal phosphide catalyst provided by the present application adopts double modification treatment of the catalyst carrier and the metal active component by alkali metal salt, alkaline earth metal salt and / or acid. For the carrier, the internal electronic structure of the carrier can be changed by alkali metal salt modification, and the internal acid amount and acid distribution state of the carrier can be changed by acid modification. For the metal component, the alkali metal salt as an auxiliary agent can improve the interaction force between the metal component and the carrier, and complex with the metal component to produce a synergistic catalytic effect, and the acid component can improve the internal distribution of the metal component and provide part of the acid center. Through the double modification of the carrier and the metal component, the hydrogen isomerization performance of the metal phosphide catalyst is significantly improved. The catalyst uses vacuum gas oil as the raw material, and can produce lubricating oil base oil with low condensation point and low pour point. The produced base oil also has low aromatic content, and the catalyst has the advantages of strong isomerization performance, outstanding aromatic saturation performance, and less viscosity index loss. At the same time, without adding a supplemental refining catalyst and process, the lubricating oil base oil can be produced. DETAILED DESCRIPTION

[0025] The following detailed description of the embodiments of the present application is given: The present embodiments are implemented on the premise of the technical solutions of the present application, and detailed implementation methods and processes are given, but the protection scope of the present application is not limited to the following embodiments. The experimental methods not specified in the following embodiments are usually performed under conventional conditions, and the % not specified is the weight %.

[0026] The application provides a preparation method of a transition metal phosphide catalyst, which comprises a carrier preparation process and an active metal solution impregnation process, and comprises two modifications, the first modification is to modify a molecular sieve used as a carrier raw material by at least one of alkali metal modification, alkali earth metal modification and acid modification to obtain a modified molecular sieve, and the second modification is to add at least one of an alkali metal compound, an alkali earth metal compound and an acid in an active metal impregnation solution.

[0027] Specifically, the modification method can be impregnation, specifically, the alkali metal compound and / or the alkali earth metal compound can be dissolved in deionized water to form a uniform modified impregnation solution, and the above-mentioned molecular sieve is impregnated in the modified impregnation solution to obtain the modified molecular sieve; the acid modification, specifically, the modification method is specifically that the acid is dissolved in deionized water to form a uniform modified impregnation solution, and the above-mentioned molecular sieve is impregnated in the modified impregnation solution to obtain the modified molecular sieve. The molecular sieve can also be impregnated in an impregnation solution formed by the alkali metal / alkali earth metal compound and an impregnation solution formed by the acid, and the application does not limit the order of impregnation of the alkali metal compound, the alkali earth metal compound and the acidic compound, for example, the alkali metal compound and / or the alkali earth metal compound can be impregnated first, and then the acid impregnation solution is impregnated; or the acid impregnation solution can be impregnated first, and then the alkali metal compound impregnation solution and / or the alkali earth metal compound is impregnated.

[0028] Further, the alkali / alkali earth metal compound is a soluble alkali / alkali earth metal salt, such as an alkali metal salt containing nitrate, an alkali metal salt containing sulfate, and an alkali metal salt containing chloride. Specifically, the concentration of the alkali / alkali earth metal in the impregnation solution formed by the alkali / alkali earth metal compound is 0.2-0.6 mol / L; and the concentration of the acid in the impregnation solution formed by the acid is 0.2-0.6 mol / L. In the impregnation process, the volume of the acid compound impregnation solution or the alkali metal compound impregnation solution used per 100 g of the molecular sieve is 60-100 ml. The modification of the molecular sieve by the acid compound or the alkali metal compound can effectively improve the pore structure properties, the specific surface area and the acid distribution of the carrier, and further improve the catalytic performance of the catalyst.

[0029] In some embodiments, preferably, the modified molecular sieve has a ten-membered ring or a twelve-membered ring structure, and simultaneously has a straight-through pore channel structure.

[0030] Specifically, the molecular sieve with the above-mentioned structure has good catalytic performance in the field of hydroisomerization.

[0031] In some embodiments, preferably, the carrier further comprises alumina and / or amorphous silica-alumina. In this way, the above-mentioned modified molecular sieve and the alumina and / or amorphous silica-alumina form a composite carrier. Further preferably, the content of the modified molecular sieve in the carrier is 40-90 wt%, and the content of the alumina and / or amorphous silica-alumina is 10-60 wt%.

[0032] In some embodiments, preferably, the modified molecular sieve has a B acid content of 0.1-0.6 mmol / g at 150°C, a ratio of B acid to L acid content of 1:2-5:1; a B acid content of 0.05-0.4 mmol / g at 350°C, a ratio of B acid to L acid content of 1:2-5:1; and a total acid amount of B acid and L acid at 150°C greater than a total acid amount of B acid and L acid at 350°C. Thus, the transition metal phosphide catalyst prepared using the molecular sieve is used to produce a lubricating oil base oil with a low pour point, and the produced base oil has the advantages of low freezing point and pour point, high liquid yield, and strong aromatic saturation performance, without the need for an additional finishing reactor to reduce the aromatic content.

[0033] In some embodiments, 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; and further preferably, the molecular sieve has a Si / Al203molar ratio of 0.1-100 and an average crystal grain size of 30-200 nm.

[0034] In some embodiments, preferably, 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, acetic acid, tartaric acid, hydrochloric acid, hydrofluoric acid, citric acid, and malic acid.

[0035] In some embodiments, preferably, the active metal solution has a transition metal as the active metal component, preferably selected from at least one of nickel, molybdenum, tungsten, cobalt, iron, and zirconium, and the active metal component in the catalyst is 10-40% by mass of the catalyst, further preferably 10-30% by mass of the catalyst.

[0036] In some embodiments, preferably, the catalyst has a molar ratio of phosphorus content to active metal component content of 1:7-7:1, further preferably 1:5-5:1. The phosphorus in the catalyst is prepared by impregnation of a solution of at least one of a phosphate, phosphoric acid, monohydrogen phosphate, dihydrogen phosphate, and hypophosphite onto the carrier.

[0037] In some embodiments, preferably, the catalyst has a mass ratio of active metal component to carrier of 1:10-1:1, a mass ratio of modified molecular sieve to alumina in the carrier of 2:3-9:1, and the two times of modification each use an additive of 1%-10% by mass of the catalyst.

[0038] In some embodiments, preferably, the catalyst has a mass ratio of active metal component to carrier of 1:9-3:7.

[0039] Example 1

[0040] Example 1-1

[0041] A SAPO-31 molecular sieve (A1) with a Si / Al203molar ratio of 0.2 and an average crystal grain size of 194 nm was selected, 40 ml of a 0.2 mol / L KCl solution was mixed with 40 ml of a 0.10 mol / L citric acid solution to obtain a mixed modification solution, and 100 g of the above molecular sieve was immersed in the mixed modification solution to obtain a modified molecular sieve (A2). The components and amounts are shown in Table 1.

[0042] The modified molecular sieve was treated by drying at 120°C for 2 hours and calcining at 500°C for 4 hours, and was used for pyridine infrared (Py-IR) characterization.

[0043] The pyridine infrared (Py-IR) characterization procedure was as follows:

[0044] After the sample was pretreated by vacuumizing in a pyridine sample cell, it was adsorbed in a pyridine sample cell in an ice bath at 0°C, and then was characterized by pyridine desorption at 150°C and 350°C. The amounts of B acid and L acid at the two desorption temperatures were calculated, and the characterization results are shown in Table 2.

[0045] Examples 1-2 to 1-8

[0046] The differences from Example 1-1 are shown in Table 1 and Table 2.

[0047] Table 1 Molecular sieve properties and modification reagents

[0048]

[0049] Table 2 Py-IR characterization results of the molecular sieve

[0050]

[0051] Example 2

[0052] The modified A2 sample in Example 1, i.e., 45 g of modified SAPO-31 molecular sieve (dry basis), was mixed with 25 g of alumina powder (dry basis) and 25 g of amorphous silica-alumina powder (dry basis, with a silica content of 50%), and was kneaded, and then was formed by an extruder. After drying at 150°C for 2 hours and calcining at 500°C for 6 hours, a carrier was prepared.

[0053] In the catalyst, the molar ratio of molybdenum (Mo) to phosphorus (P) was 1:1, and the total loading of molybdenum and phosphorus elements was 10%. Ammonium molybdate ((NH4)6Mo7O 24• 4H2O) 13.93 g, diammonium hydrogen phosphate ((NH4)2HPO4) 10.47 g and KCl powder 3.45 g were dissolved in 100 ml of 5 mol / l ammonia water, heated to constant volume to 60 ml, and used as prepared.

[0054] The solution was impregnated onto the catalyst carrier, impregnated at 25°C (room temperature) for 2 h, and then dried at 80°C for 3 h to obtain catalyst precursor A.

[0055] Example 3

[0056] The modified B2 and C2 samples in Example 1, i.e. 20 g (dry base weight) of ZSM-22 molecular sieve, 16 g (dry base weight) of SAPO-11 molecular sieve, were kneaded with 35 g of alumina powder (dry base weight) and 19 g of amorphous silica-alumina powder (dry base weight, silica content 30%), formed by an extruder, and after drying the wet strips at 120°C for 3 hours and calcining at 550°C for 4 hours, a carrier was prepared.

[0057] The tungsten (W) and phosphorus (P) in the catalyst were calculated according to a molar ratio of 1:1, and the total loading of tungsten and phosphorus elements was 10%. Ammonium metatungstate ((NH4)6W 12 O 39 • 4H2O) 13.93 g, diammonium hydrogen phosphate ((NH4)2HPO4) 10.47 g and KCl powder 3.45 g were dissolved in 100 ml of 5 mol / l ammonia water, heated to constant volume to 60 ml, and used as prepared.

[0058] The solution was impregnated onto the catalyst carrier, impregnated at 25°C (room temperature) for 2 h, and then dried at 60°C for 5 h to obtain catalyst precursor B.

[0059] Example 4

[0060] The modified D2, E2 and F2 samples in Example 1, i.e. 20 g (dry base weight) of MCM-22 molecular sieve, 21 g (dry base weight) of SAPO-41 molecular sieve, 21 g (dry base weight) of ZSM-35 molecular sieve, were kneaded with 8 g of alumina powder (dry base weight), formed by an extruder, and after drying the wet strips at 120°C for 3 hours and calcining at 550°C for 4 hours, a carrier was prepared.

[0061] The nickel (Ni) and phosphorus (P) in the catalyst were calculated according to a molar ratio of 2:1, and the total loading of nickel and phosphorus elements was 30%. Nickel nitrate (Ni(NO3)2·6H2O) 118 g, ammonium hypophosphite ((NH4)2HPO3) 23.6 g and 7 g of citric acid were dissolved in 250 ml of deionized water, heated to constant volume to 200 ml, and used as prepared.

[0062] The solution was impregnated onto the catalyst carrier twice, 100 ml each time, after each impregnation, impregnation was carried out at 25°C (room temperature) for 4 h, then drying at 80°C for 4 h, finally obtaining catalyst precursor C.

[0063] Comparative Example 1

[0064] The difference from Example 4 is that the unmodified D1, E1 and F1 samples were taken, and the remaining steps were the same as Example 4, and the catalyst precursor obtained was DC.

[0065] Example 5

[0066] The modified G2 and H2 samples in Example 1, i.e. 35 g of ZSM-23 molecular sieve (dry base weight), 25 g of ZSM-48 molecular sieve (dry base weight), were taken, mixed with 15 g of alumina powder (dry base weight) and 10 g of amorphous silica-alumina powder (dry base weight, silica content 40%), and extruded through an extruder, and the wet strips were dried at 120°C for 3 hours and calcined at 550°C for 4 hours to prepare the carrier.

[0067] In the catalyst, the molar ratio of nickel (Ni) to phosphorus (P) was 1:5, and the total loading of nickel and phosphorus elements was 15%. 20.4 g of nickel nitrate (Ni(NO3)2·6H2O), 40.8 g of ammonium hypophosphite ((NH4)2HPO3) and 7 g of ZnCl2 were dissolved in 150 ml of deionized water, heated and diluted to 80 ml, and used as prepared.

[0068] The solution was impregnated onto the catalyst carrier, after each impregnation, impregnation was carried out at 25°C (room temperature) for 3 h, then drying at 80°C for 3 h, finally obtaining catalyst precursor D.

[0069] Example 6

[0070] The difference from Example 5 is that: in the catalyst, the molar ratio of nickel (Ni) to phosphorus (P) was 5:1, and the total loading of nickel and phosphorus elements was 15%. 67.7 g of nickel nitrate (Ni(NO3)2·6H2O), 5.4 g of ammonium hypophosphite ((NH4)2HPO3) and 8 g of magnesium nitrate were dissolved in 150 ml of deionized water, heated and diluted to 80 ml, and used as prepared. The remaining steps were the same, and finally catalyst precursor E was obtained.

[0071] Comparative Example 2

[0072] The difference from Example 6 is that no magnesium nitrate is added in the preparation of the impregnation solution, and the remaining steps are the same as Example 6, and catalyst precursor DE is obtained.

[0073] Example 7

[0074] The difference between Example 6 is that: the molar ratio of nickel (Ni) to phosphorus (P) in the catalyst is 1:5, the total loading of nickel and phosphorus elements is 15%, take 20.4g of nickel nitrate (Ni(NO3)2·6H2O), 13.6g of ammonium hypophosphite ((NH4)2HPO3) and 7g of tartaric acid together into 150ml of deionized water, heat to constant volume to 80ml, and prepare for use. The rest is the same. Finally, catalyst precursor F is obtained.

[0075] Example 8

[0076] Take the modified G2 sample in Example 1, that is, ZSM-23 molecular sieve 75g (dry basis), mix with 6g of alumina powder (dry basis) and 4g of amorphous silica-alumina powder (dry basis, silica content is 40%), and then extrude through an extruder. After drying at 120℃ for 3 hours and calcining at 550℃ for 4 hours, the carrier is prepared.

[0077] The molar ratio of nickel (Ni) to phosphorus (P) in the catalyst is 3:1, and the total loading of nickel and phosphorus elements is 15%. Take 42.78g of nickel nitrate (Ni(NO3)2·6H2O), 8.5g of ammonium hypophosphite ((NH4)2HPO3) and 6g of barium nitrate together into 150ml of deionized water, heat to constant volume to 80ml, and prepare for use.

[0078] The solution is impregnated onto the catalyst carrier. After each impregnation, it is immersed at 25℃ (room temperature) for 3h, and then dried at 80℃ for 3h. Finally, catalyst precursor G is obtained.

[0079] Comparative Example 3

[0080] The same as Example 8 is that: take the unmodified G1 sample, and do not add barium nitrate in the preparation of the impregnation solution. The rest of the steps are the same as Example 8, and the catalyst precursor obtained is DG.

[0081] Example 9

[0082] The catalyst precursors obtained in Examples 2 to 8 and Comparative Examples 1 to 3 are respectively taken 100ml and loaded into a fixed bed reactor. Under a hydrogen atmosphere, the hydrogen pressure is 2MPa, the hydrogen flow is 30L / h, and the temperature is kept at 450℃ for 6h. Then, the temperature is lowered to 60℃ and nitrogen is blown. Under the same pressure and gas flow, the blowing is carried out for 4h. Catalysts A-cat, B-cat, C-cat, D-cat, E-cat, F-cat, G-cat, DC-cat, DE-cat and DG-cat are obtained.

[0083] Example 10

[0084] The catalysts prepared in Example 9 were selected for hydrogenation evaluation. Six catalysts, 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 a vacuum gas oil after hydrotreating, and the properties of the feedstock oil are shown in Table 4. The hydrogenation evaluation products were cut by true boiling point, and the properties of the products greater than 360℃ are shown in Table 5.

[0085] Table 3 Hydrogenation evaluation process conditions

[0086] Reaction temperature, °C 350 Hydrogen partial pressure, MPa 12 Liquid hourly space velocity, h -1 ]]> 1.0 Hydrogen to oil volume ratio 400

[0087] Table 4 Properties of the feedstock oil

[0088]

[0089]

[0090] Table 5 Hydrogenation evaluation results

[0091]

[0092] As shown in Tables 3 to 5, the preparation method of the transition metal phosphide catalyst provided by the present application uses alkali metal salts, alkaline earth metal salts and / or acids to perform double modification treatment on the catalyst carrier and the metal active component. For the carrier, modification by alkali metal salts can change the internal electronic structure of the carrier, and modification by acids can change the amount and distribution state of the acid in the carrier. For the metal component, the alkali metal salts as an additive can improve the force between the metal component and the carrier, and complex with the metal component to produce a synergistic catalytic effect, and the acid component can improve the distribution of the metal component in the carrier and provide some acid centers. Through double modification of the carrier and the metal component, the hydrogenation isomerization performance of the metal phosphide catalyst is significantly improved. The catalyst uses vacuum gas oil as the raw material, and can produce lubricating oil base oil with low freezing point and low pour point. The base oil produced has low aromatic content, and the catalyst has strong isomerization performance, outstanding aromatic saturation performance, and less viscosity index loss. At the same time, without adding a supplemental refining catalyst and process, the lubricating oil base oil produced is qualified.

[0093] Of course, the present application also has other various embodiments, and those skilled in the art can make various corresponding changes and modifications to the present application without departing from the spirit and essence of the present application. However, these corresponding changes and modifications should all belong to the protection scope of the present application.

Claims

1. A method for preparing a transition metal phosphide catalyst for producing low-pour-point, low-melt-point lubricating oil base oil, comprising a support preparation process and an active metal 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 modified molecular sieve and alumina and / or amorphous silica-alumina form a composite carrier. The second modification involves adding at least one of alkali metal compound, alkaline earth metal compound, and acid to an active metal impregnation solution and impregnating the resulting solution onto the composite carrier. The active metal impregnation solution is a mixed solution of an active metal source solution and a phosphorus source solution. The phosphorus source is at least one of phosphate, phosphoric acid, monohydrogen phosphate, dihydrogen phosphate, and hypophosphite. 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; the Si / Al2O3 molar ratio in the molecular sieve is 0.1 to 100. 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 modified molecular sieve has a ten-membered ring or a twelve-membered ring structure, and also has a straight-through channel structure.

3. The preparation method according to claim 1, characterized in that, The carrier contains 40–90 wt% modified molecular sieve and 10–60 wt% alumina and / or amorphous silica-alumina.

4. The preparation method according to claim 1, characterized in that, The average grain size of the molecular sieve is 30–200 nm.

5. 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, acetic acid, tartaric acid, hydrochloric acid, hydrofluoric acid, citric acid, and malic acid.

6. The preparation method according to claim 1, characterized in that, The active metal component in the active metal solution is selected from at least one of nickel, molybdenum, and tungsten, and the active metal component in the catalyst accounts for 10-40% of the catalyst mass as an oxide.

7. The preparation method according to claim 6, characterized in that, The active metal component in the catalyst accounts for 10-30% of the catalyst mass, calculated as oxides.

8. The preparation method according to claim 1, characterized in that, The molar ratio of phosphorus content to metal active component content in the catalyst is 1:7 to 7:

1.

9. The preparation method according to claim 8, characterized in that, The molar ratio of phosphorus content to metal active component content in the catalyst is 1:5 to 5:

1.

10. The preparation method according to claim 6, characterized in that, The mass ratio of the active metal component to the support in the catalyst is 1:10 to 1:1, and the mass ratio of the modified molecular sieve to alumina in the support is 2:3 to 9:

1.

11. The preparation method according to claim 10, characterized in that, The mass ratio of the active metal component to the support in the catalyst is 1:9 to 3:7.

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