A method for producing a low pour point base oil

Abstract

The application discloses a production method of low pour point base oil, which comprises the following steps: carrying out a hydrogen isomerization reaction on the hydrogenated wax oil under the action of at least one metal phosphide catalyst to obtain the low pour point base oil, and the metal phosphide catalyst comprises a metal component and a carrier, and the metal phosphide catalyst is subjected to twice modification treatment, wherein the first modification is to introduce a modification aid into the carrier, and the second modification is to introduce the modification aid into the metal component. The production method of the low pour point base oil can produce the lubricating oil base oil with low pour point and low aromatic hydrocarbon, and has high total base oil yield and low viscosity index loss, and overcomes the weakness that the base oil produced in the process of producing the lubricating oil base oil from the hydrogenated wax oil by using the traditional metal phosphide catalyst has high pour point and freezing point temperature and cannot meet the use requirement.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of base oil production, and particularly relates to a production method of low pour point base oil. BACKGROUND

[0002] Lubricating oil is one of the four major products of the petroleum industry, and plays an important role in the development of modern industry. The main production processes of high-end lubricating oil production at present include catalytic dewaxing and isomerization dewaxing (hydroisomerization) processes. The isomerization dewaxing (hydroisomerization) technology is an advanced lubricating oil processing technology newly appeared in the world, which can process raw materials with relatively high wax content. Through the hydroisomerization reaction of wax components with high viscosity index and high freezing point, the lubricating oil components with high viscosity index and low freezing point are converted, instead of cracking into low-boiling components, thereby improving the yield of base oil and retaining the viscosity index. The isomerization dewaxing technology not only has a high product yield, but also can obtain high-quality lubricating oil base oil, and has high industrial value.

[0003] The technical core of hydroisomerization is the isomerization dewaxing catalyst. The catalyst mainly uses molecular sieve with shape-selective function as the carrier, and uses noble metal with high hydrogenation activity as the metal active center. In the shape-selective catalytic process, the metal active center of the catalyst and the carrier function need to be reasonably matched. In order to improve the catalytic activity of the catalyst, researchers have improved the hydrogenation isomerization catalyst. From the perspective of catalyst cost, non-noble metal catalysts have been developed and researched. Metal phosphides, as a new type of active phase structure, have the characteristics of "noble metal", and show good hydrogenation and dehydrogenation activity. Research has been attempted in the field of hydroisomerization. The catalyst carrier has been researched. The molecular sieve is modified by alkali metal or alkaline earth metal to adjust the acid amount of the molecular sieve and improve the activity of the catalyst. Organic complexes such as organic amines are used to modify the carrier.

[0004] Chinese patent CN1492025A discloses a preparation method of a supported transition metal phosphide fraction oil deep hydrodesulfurization catalyst, the steps are: dissolving the salt of transition metal and phosphate in water, adjusting the pH value to 2-4, under vacuum conditions, dropping the prepared solution into the carrier, impregnating for 1-10 hours, then quickly evaporating water, drying at 80-180°C for 10-14 hours, calcining in air at 300-600°C for 1-10 hours, to obtain a supported transition metal phosphide oxidation state deep hydrodesulfurization catalyst, the carrier is a composite of mesoporous molecular sieve and / or porous oxide, wherein the mass percentage content of mesoporous molecular sieve is 0-100%, the mass percentage content of porous oxide is 0-100%, the mesoporous molecular sieve is MCM-41 or SBA-15 / 16, the porous oxide is Y zeolite molecular sieve, ZSM-5 zeolite molecular sieve, mordenite molecular sieve, beta zeolite molecular sieve, A type zeolite molecular sieve, X type zeolite molecular sieve, MCM-22 molecular sieve, AlPO4 type molecular sieve, alumina, silica, titanium oxide, zirconium oxide or binary, multi-component composite thereof. The transition metal is Ni, Mo, Co, Mo, W, Fe, Mn, Pt, Pd, Ru or binary, multi-component composite thereof.

[0005] US patents US7141529B2, 5246566 disclose a method for improving the selectivity of the catalyst by modifying the molecular sieve with alkali metal or alkaline earth metal, adjusting the acid amount of the molecular sieve.

[0006] Chinese patent CN02109409.8 discloses a preparation method of a hydroisomerization catalyst, taking SAPO-11 as the main carrier, and pre-treating the catalyst carrier with organic amine to retain the acidity of the molecular sieve to improve the activity of the catalyst.

[0007] Chinese patent 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 and cesium, the alkaline earth metal is selected from strontium and 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, the ion exchange method is adopted to make the cation distribution of the Y molecular sieve present that the internal is NH4 +The external part is alkali metal (or alkaline earth metal) ion, and the internal part is Y zeolite, and the external part is characterized by alkali metal (or alkaline earth metal) ion, and the skeleton is stabilized by the alkali metal (or alkaline earth metal) ion, so that the external part of the molecular sieve is protected to some extent in the dealumination, and the internal part of the molecular sieve is preferentially dealuminated. By changing the type, exchange condition and other factors of the alkali metal (or alkaline earth metal) ion, the exchange position and exchange amount of the alkali metal (or alkaline earth metal) ion can be changed, and then the internal and external aluminum atom distribution and acid site distribution of the dealuminated Y molecular sieve can be adjusted.

[0008] Chinese patent 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.

[0009] The metal phosphide catalyst has made good progress in the research of hydroisomerization, but it has weak catalytic activity in producing low pour point lubricating oil base oil from wax oil, and the effect of reducing the pour point is poor. It is expected to improve the existing production process to improve the hydroisomerization performance of wax oil and produce low pour point lubricating oil base oil. SUMMARY

[0010] The main purpose of the present application is to provide a production method of low pour point base oil, which is used to better reduce the low temperature performance of base oil products, and for lubricating oil base oil, it is to reduce the pour point and freezing point performance of base oil, so as to overcome the problem of insufficient ability of non-noble metal catalyst in reducing the pour point and freezing point of lubricating oil base oil in the prior art.

[0011] In order to achieve the above purpose, the present application provides a production method of low pour point base oil, which comprises: hydroisomerization reaction of hydroprocessed wax oil under the action of at least one metal phosphide catalyst to obtain low pour point base oil, wherein the metal phosphide catalyst comprises metal components and carriers, and the metal phosphide catalyst is subjected to two modification treatments, the first modification is to introduce a modification aid into the carrier, and the second modification is to introduce a modification aid into the metal component.

[0012] The production method of low pour point base oil of the present application, the modification aid is alkali metal and / or acid.

[0013] The production method of low pour point base oil of the present application, the carrier comprises modified molecular sieve and alumina and / or amorphous silicon aluminum.

[0014] The production method of the low pour point base oil of the present application, the first modification is to modify the molecular sieve with a modification aid to obtain a modified molecular sieve; the second modification is to prepare a homogeneous solution of the modification aid and a metal component salt, and then impregnate the carrier.

[0015] The production method of the low pour point base oil of the present application, the modified molecular sieve is characterized by a pyridine infrared (Py-IR) method, the B acid content at 150℃ is 0.1-0.6 mmol / g, and the molar content ratio of B acid to L acid is 1:2-5:1; the B acid content at 350℃ is 0.05-0.4 mmol / g, and the molar content ratio of B acid to L acid is 1:2-5:1; wherein the total acid amount of B acid and L acid at 150℃ is greater than that at 350℃.

[0016] The production method of the low pour point base oil of the present application, the molecular sieve has a ten-membered ring or a twelve-membered ring topology and has a straight-through pore structure; the molar ratio of Si / Al2O3 in the molecular sieve is 0.1-100, and the average crystal grain size is 30-200 nm.

[0017] The production method of the low pour point base oil of the present application, the molecular sieve is at least one of SAPO-31, SAPO-11, ZSM-22, MCM-22, SAPO-41, ZSM-23, ZSM-35 and ZSM-48.

[0018] The production method of the low pour point base oil of the present application, the alkali metal is a group IA or IIA metal, which can be lithium, sodium, potassium, rubidium, cesium, francium, beryllium, magnesium, calcium, strontium, barium, radium; the acid is at least one of nitric acid, phosphoric acid, acetic acid, tartaric acid, hydrochloric acid, hydrofluoric acid and citric acid.

[0019] The production method of the low pour point base oil of the present application, the metal component is selected from at least one of nickel, molybdenum and tungsten, which exists in the form of a chemical bond in the metal phosphide catalyst; in the metal phosphide catalyst, the phosphorus component is selected from at least one of a phosphate, phosphoric acid, monohydrogen phosphate, dihydrogen phosphate and hypophosphite; in the metal phosphide catalyst, the total content of the metal component and phosphorus accounts for 10-40wt% of the mass of the metal phosphide catalyst, preferably 10-30wt%; in the metal phosphide catalyst, the molar ratio of phosphorus to the metal component is 1:7-7:1, preferably 1:5-5:1.

[0020] The production method of the low pour point base oil of the present application, in the metal phosphide catalyst, the mass ratio of the metal component to the carrier is 1:10-1:1, preferably 1:9-3:7; in the carrier, the mass ratio of the modified molecular sieve to alumina is 2:3-9:1, and the modified aid accounts for 1wt%-10wt% of the mass of the metal phosphide catalyst, preferably 1wt%-5wt%.

[0021] The production method of the low pour point base oil of the present application, the hydroprocessed wax oil is selected from at least one of hydrocracking tail oil, second line cut wax oil, third line cut wax oil, fourth line cut wax oil.

[0022] The production method of the low pour point base oil of the present application, the sulfur content of the hydroprocessed wax oil is not more than 200 μg / g, the nitrogen content is not more than 100 μg / g; preferably the sulfur content is not more than 100 μg / g, the nitrogen content is not more than 50 μg / g; most preferably the sulfur content is not more than 50 μg / g, the nitrogen content is not more than 30 μg / g.

[0023] The production method of the low pour point base oil of the present application, the distillation range of the hydroprocessed wax oil is 300-600℃, preferably 350-580℃.

[0024] The production method of the low pour point base oil of the present application, the hydroisomerization reaction pressure is 10-15 MPa, the reaction temperature is 320-400℃, the volume space velocity is 0.8-2.0 h -1 In the hydroisomerization reaction, the base oil has less viscosity index loss and high viscosity, and the base oil with pour point not more than -12℃ can be produced.

[0025] The production method of the low pour point base oil of the present application, the metal phosphide is used as the catalyst, the catalyst is modified twice, the acidity of the carrier and the electronic structure of the carrier are adjusted by carrier modification, the synergistic catalysis of the additive and the metal component is produced by metal component modification, the metal component is highly dispersed on the carrier after being loaded on the carrier, and the catalyst with high hydroisomerization activity is obtained. The low pour point lubricating base oil is produced in the reactor by hydroisomerization reaction using the hydroprocessed wax oil as the raw material. By the production method of the low pour point base oil of the present application, the lubricating base oil with low pour point and low aromatic hydrocarbon can be produced, the total base oil yield is high, the viscosity index loss is less, and the weakness that the base oil produced in the process of producing the lubricating base oil using the hydroprocessed wax oil as the raw material by the traditional metal phosphide catalyst has high pour point and freezing point temperature and cannot meet the use requirement is overcome. DETAILED DESCRIPTION

[0026] The examples of the present application are described in detail as follows: The examples are implemented on the premise of the technical scheme of the present application, and detailed implementation modes and processes are given, but the protection scope of the present application is not limited to the following examples. The experimental methods not specified in the following examples are usually performed according to the conventional conditions.

[0027] The application provides a production method of low pour point base oil, characterized by using hydroprocessed wax oil as raw material, using metal phosphide catalyst as catalytic medium, mixing the hydroprocessed wax oil with hydrogen, and then performing hydroisomerization reaction on the mixture through the metal phosphide catalyst to produce the low pour point base oil.

[0028] The modified molecular sieve is obtained by modifying a molecular sieve with an alkali metal and / or an acid modification agent, and the molecular sieve has a ten-membered ring or a twelve-membered ring structure and a straight-through channel structure.

[0029] In an embodiment, the molecular sieve is one or more of SAPO-31, SAPO-11, ZSM-22, MCM-22, SAPO-41, ZSM-23, ZSM-35 and ZSM-48, i.e., is selected from molecular sieves having a ten-membered ring or a twelve-membered ring structure. Through experiments, it is found that the molecular sieves having a ten-membered ring or a twelve-membered ring structure have good catalytic performance in the field of hydroisomerization, and the molecular sieves have a straight-through channel structure. In another embodiment, the Si / Al2O3 molar ratio of the molecular sieve is 0.1-100, and the average crystal grain size is 30-200 nm.

[0030] In an embodiment, the above-mentioned molecular sieve is modified with an alkali metal and / or an acid modification agent to obtain a modified molecular sieve. The modification method can be an impregnation method. Specifically, an alkali metal compound can be dissolved in deionized water to form a uniform modification impregnation solution, and the above-mentioned molecular sieve is impregnated in the modification impregnation solution to obtain a modified molecular sieve. The acid compound modification method specifically includes dissolving an acid compound in deionized water to form a uniform modification impregnation solution, and impregnating the above-mentioned molecular sieve in the modification impregnation solution to obtain a modified molecular sieve. The molecular sieve can also be impregnated in an impregnation solution formed by an alkali metal compound and an impregnation solution formed by an acid compound. The application does not limit the order of impregnating the alkali metal compound and the acid compound. For example, the alkali metal compound impregnation solution can be impregnated first, and then the acid compound impregnation solution can be impregnated. Alternatively, the acid compound impregnation solution can be impregnated first, and then the alkali metal compound impregnation solution can be impregnated.

[0031] In one embodiment, the alkali metal is selected from one or more of the group IA and IIA metals, such as lithium, sodium, potassium, rubidium, cesium, francium, beryllium, magnesium, calcium, strontium, barium, radium, and the like. The alkali metal compound is a soluble alkali metal salt, such as an alkali metal salt containing nitrate, an alkali metal salt containing sulfate, an alkali metal salt containing chloride. The acidic compound can be one or more of nitric acid, phosphoric acid, acetic acid, tartaric acid, hydrochloric acid, citric acid, tartaric acid, or malic acid. In another embodiment, the concentration of the alkali metal in the impregnation solution formed by the alkali metal compound is 0.2-0.6 mol / L, and the concentration of the acidic compound in the impregnation solution formed by the acidic compound is 0.2-0.6 mol / L. In the impregnation process, the volume of the acidic 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 with the acidic 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.

[0032] The above-mentioned molecular sieve is modified with alkali metal and / or acid to obtain a modified molecular sieve. The modified molecular sieve is characterized by pyridine infrared. At 150°C, the B acid content is 0.1-0.6 mmol / g, and the molar content ratio of B acid to L acid is 1:2-5:1. At 350°C, the B acid content is 0.05-0.4 mmol / g, and the molar content ratio of B acid to L acid is 1:2-5:1. The total acid amount at 150°C (i.e., the acid amount of B acid+L acid) is greater than the total acid amount at 350°C (i.e., the acid amount of B acid+L acid). 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. The produced base oil has the advantages of low freezing point and pour point, high liquid yield, and strong aromatic saturation performance, and does not need to increase a supplemental refining reactor to reduce the aromatic content.

[0033] In one embodiment, the catalyst carrier of the present application further comprises alumina or alumina and amorphous silica-alumina. Thus, the above-mentioned modified molecular sieve and the alumina and / or amorphous silica-alumina form a composite carrier. The metal active component of the catalyst of the present application can be one or more of nickel, molybdenum, tungsten, cobalt, iron, and zirconium, and the phosphorus element is selected from one or more of phosphate, phosphoric acid, monohydrogen phosphate, dihydrogen phosphate, and hypophosphite. In another embodiment, the content of the carrier in the catalyst is 65-90 wt% based on the total mass of the catalyst, and the total content of the metal active component and the phosphorus element is 10-40 wt%. Further, the content of the molecular sieve in the carrier is, for example, 40-90 wt%, and the content of the alumina and / or amorphous silica-alumina in the carrier is, for example, 10-60 wt%.

[0034] The above-mentioned molecular sieve type and modification method have been described in detail, and will not be repeated here.

[0035] The technical solutions of the present application are further described below through specific examples.

[0036] Examples 1-8

[0037] (1) Preparation of modified molecular sieve

[0038] In Examples 1-8, SAPO-31, ZSM-22, SAPO-11, MCM-22, SAPO-41, ZSM-23, ZSM-35 and ZSM-48 are commercially available or prepared by any existing method, preferably with a Si / Al203molar ratio of 0.1-100 and an average crystal size of 30-200 nm. The molecular sieve is modified by an alkali metal solution or an acidic solution, wherein the alkali metal is selected from Group IA or IIA metals, and the acid is selected from one or more of nitric acid, phosphoric acid, acetic acid, tartaric acid, hydrochloric acid, citric acid, tartaric acid or malic acid, and the modification process is to impregnate the molecular sieve with a solution of the modification aid, i.e. Group IA or IIA metal salt or the above-mentioned acid, at a concentration of 0.2-0.6 mol / L, with a ratio of the mass of the molecular sieve (unit: g) to the volume of the impregnation liquid (unit: mL) being 100:60-100. Taking 100 g of the original molecular sieve powder as an example, A1, B1, C1, D1, E1, F1 and G1 samples are the original molecular sieve powder without modification treatment, and the SiO2 / Al203molar ratio, average crystal size, modification reagent used and amount are shown in Table 1.

[0039] Table 1 Molecular sieve properties and modification reagents

[0040]

[0041] (2) Characterization of modified molecular sieve and preparation of metal phosphide catalyst

[0042] The modified molecular sieve in Table 1 is treated by drying at 120°C for 2 hours and calcining at 500°C for 4 hours, and used for pyridine infrared (Py-IR) characterization and preparation of metal phosphide catalyst.

[0043] The sample is pretreated by vacuum pumping in a pyridine sample cell, then adsorbed in a pyridine sample cell in an ice bath at 0°C, and then characterized by pyridine desorption at 150°C and 350°C. The amounts of B acid and L acid at the two desorption temperatures of 150°C and 350°C are calculated, and the characterization results are shown in Table 2.

[0044] Table 2 Py-IR characterization results of molecular sieve

[0045]

[0046] Example 9

[0047] Take the sample A2 in the above examples, i.e. 45 g of modified SAPO-31 molecular sieve (dry base weight), mix with 25 g of alumina powder (dry base weight) and 25 g of amorphous silica-alumina powder (dry base weight, silica content of 50 wt%), pass through an extruder to form a wet strip, dry the wet strip at 150°C for 2 hours and calcine at 500°C for 6 hours to prepare the carrier.

[0048] The molar ratio of molybdenum (Mo) to phosphorus (P) in the catalyst is 1:1, and the total loading of molybdenum and phosphorus elements is 10%. Take 13.93 g of ammonium molybdate ((NH4)6Mo7O 24 ·4H2O), 10.47 g of diaminium hydrogen phosphate ((NH4)2HPO4) and 3.45 g of KCl powder, dissolve them in 100 mL of 5 mol / L ammonia water, heat and dilute to 60 mL, and prepare for use.

[0049] Impregnate the solution into the catalyst carrier, immerse at 25°C (room temperature) for 2 hours, then dry at 80°C for 3 hours to obtain catalyst precursor A.

[0050] Example 10

[0051] Take the samples B2 and C2 in the above examples, i.e. 20 g of modified ZSM-22 molecular sieve (dry base weight) and 16 g of modified SAPO-11 molecular sieve (dry base weight), mix with 35 g of alumina powder (dry base weight) and 19 g of amorphous silica-alumina powder (dry base weight, silica content of 30%), pass through an extruder to form a wet strip, dry the wet strip at 120°C for 3 hours and calcine at 550°C for 4 hours to prepare the carrier.

[0052] The molar ratio of tungsten (W) to phosphorus (P) in the catalyst is 1:1, and the total loading of tungsten and phosphorus elements is 10%. Take 11.54 g of ammonium metatungstate ((NH4)6W 12 O 39 ·2H2O), 5.37 g of ammonium dihydrogen phosphate (NH4H2PO4) and 6 g of 67% HNO3 solution, dissolve them in 100 mL of deionized water, heat and dilute to 80 mL, and prepare for use.

[0053] Impregnate the solution into the catalyst carrier, immerse at 25°C (room temperature) for 2 hours, then dry at 60°C for 5 hours to obtain catalyst precursor B.

[0054] Example 11

[0055] Take the samples D2, E2 and F2 in the above examples, i.e. 20 g of modified MCM-22 molecular sieve (dry base weight), 21 g of modified SAPO-41 molecular sieve (dry base weight) and 21 g of modified ZSM-35 molecular sieve (dry base weight), mix with 8 g of alumina powder (dry base weight), pass through an extruder to form a wet strip, dry the wet strip at 120°C for 3 hours and calcine at 550°C for 4 hours to prepare the carrier.

[0056] The total loading of nickel and phosphorus elements in the catalyst is 30% according to the molar ratio of 2:1 of nickel (Ni) to phosphorus (P). Take 118 g of nickel nitrate (Ni(NO3)2·6H2O), 23.6 g of ammonium hypophosphite ((NH4)2HPO3) and 7 g of citric acid together and dissolve them in 250 mL of deionized water. Heat and dilute to 200 mL, and prepare for use.

[0057] The solution is impregnated onto the catalyst carrier twice, 100 mL each time. After each impregnation, impregnate at 25°C (room temperature) for 4 h, then dry at 80°C for 4 h. Finally, catalyst precursor C is obtained.

[0058] Comparative Example 1

[0059] The difference from Example 11 is that no citric acid is added in the preparation of the impregnation solution, and the remaining steps are the same as Example 11. The catalyst precursor obtained is DC.

[0060] Example 12

[0061] Take the G2 and H2 samples in the above examples, i.e. 35 g of modified ZSM-23 molecular sieve (dry base weight), 25 g of modified ZSM-48 molecular sieve (dry base weight), 15 g of alumina powder (dry base weight) and 10 g of amorphous silica-alumina powder (dry base weight, silica content 40%) are kneaded, and then formed into strips by an extruder. After drying at 120°C for 3 hours and calcining at 550°C for 4 hours, the carrier is prepared.

[0062] The total loading of nickel and phosphorus elements in the catalyst is 15% according to the molar ratio of 1:5 of nickel (Ni) to phosphorus (P). Take 20.4 g of nickel nitrate (Ni(NO3)2·6H2O), 40.8 g of ammonium hypophosphite ((NH4)2HPO3) and 7 g of ZnCl2 together and dissolve them in 150 mL of deionized water. Heat and dilute to 80 mL, and prepare for use.

[0063] The solution is impregnated onto the catalyst carrier. After each impregnation, impregnate at 25°C (room temperature) for 3 h, then dry at 80°C for 3 h. Finally, catalyst precursor D is obtained.

[0064] Example 13

[0065] The difference from Example 12 is that the total loading of nickel and phosphorus elements in the catalyst is 15% according to the molar ratio of 5:1 of nickel (Ni) to phosphorus (P). Take 67.7 g of nickel nitrate (Ni(NO3)2·6H2O), 5.4 g of ammonium hypophosphite ((NH4)2HPO3) and 8 g of magnesium nitrate together and dissolve them in 150 mL of deionized water. Heat and dilute to 80 mL, and prepare for use. The remaining steps are the same, and finally catalyst precursor E is obtained.

[0066] Comparative Example 2

[0067] The difference between Example 13 and Example 14 is that the sample G1 and H1 are not modified, and the rest of the steps are the same as Example 13, and the catalyst precursor is DE.

[0068] Example 14

[0069] The difference between Example 13 and Example 14 is that the sample G1 and H1 are not modified, and the rest of the steps are the same as Example 13, and the catalyst precursor is DE.

[0070] Example 15

[0071] The sample G2 in the above examples, i.e. ZSM-23 molecular sieve 75g (dry basis), is mixed with 6g of alumina powder (dry basis) and 4g of amorphous silica-alumina powder (dry basis, silica content 40%), and then extruded into a strip through an extruder. After drying at 120°C for 3 hours and calcining at 550°C for 4 hours, the carrier is prepared.

[0072] The difference between Example 13 and Example 14 is that the sample G1 and H1 are not modified, and the rest of the steps are the same as Example 13, and the catalyst precursor is DE.

[0073] The solution is impregnated onto the catalyst carrier, and after each impregnation, it is immersed at 25°C (room temperature) for 3h, and then dried at 80°C for 3h. Finally, the catalyst precursor G is obtained.

[0074] Comparative Example 3

[0075] The difference between Example 15 and Comparative Example 3 is that the sample G1 is not modified, and no barium nitrate is added in the preparation of the impregnation solution, and the rest of the steps are the same as Example 15, and the catalyst precursor is DG.

[0076] Example 16

[0077] The catalyst precursors obtained in Example 9 to Example 15, Comparative Example 1 to Comparative Example 3 were respectively taken 100 mL into a fixed bed reactor, under hydrogen atmosphere, hydrogen pressure 2 MPa, hydrogen flow rate 30 L / h, 450℃ constant temperature for 6 h, then reduced to 60℃ to switch to nitrogen purge, under the same pressure and gas flow rate, purging for 4 h, to obtain catalyst A-cat, B-cat, C-cat, D-cat, E-cat, F-cat, G-cat, DC-cat, DE-cat and DG-cat.

[0078] Example 17

[0079] The catalyst prepared in Example 16 was selected for hydrogenation evaluation. Six catalysts were selected, namely C-cat, E-cat, G-cat, DC-cat, DE-cat and DG-cat for hydrogenation performance evaluation. A fixed bed reactor was used, and the catalyst loading volume was 100 mL.

[0080] Example 18

[0081] The loading scheme of Example 17 was used, and metal phosphide catalyst was used for hydrogenation isomerization reaction to produce lubricating oil base oil. The dewaxed vacuum gas oil was mixed with hydrogen in a heating furnace, and the mixed oil and gas were introduced into a fixed bed reactor for hydrogenation isomerization reaction. The hydrogenation evaluation process conditions are shown in Table 3, and the properties of the raw oil are shown in Table 4.

[0082] Table 3 Hydrogenation evaluation process conditions

[0083] Reaction temperature, °C 335 Hydrogen partial pressure, MPa 13 Liquid hourly space velocity, h -1 ]] 1.5 Hydrogen to oil volume ratio 400

[0084] Table 4 Properties of raw oil

[0085]

[0086] The hydrogenation evaluation products were cut by a fractionation system, and the properties of the products greater than 350℃ are shown in Table 5.

[0087] Table 5 Hydrogenation evaluation results

[0088]

[0089]

[0090] Example 19

[0091] The loading scheme of Example 17 was adopted to produce lubricating base oil by using metal phosphide catalyst to perform hydroisomerization reaction on hydrocracking tail oil as raw material. The vacuum gas oil was mixed with hydrogen in a mixer, and the mixed oil and gas were introduced into a fixed bed reactor through a pipeline to perform hydroisomerization reaction. The hydroisomerization process conditions are shown in Table 6, and the properties of the raw oil are shown in Table 7.

[0092] Table 6 Hydroisomerization process conditions

[0093] Reaction temperature, °C 350 Hydrogen partial pressure, MPa 8 Liquid hourly space velocity, h -1 ]] 1.8 Hydrogen to oil volume ratio 300

[0094] Table 7 Properties of raw oil

[0095]

[0096]

[0097] The hydroisomerization product was cut by a fractionation system, and the properties of the product greater than 310℃ are shown in Table 8.

[0098] Table 8 Hydroisomerization results

[0099]

[0100] From the results of the above examples and comparative examples, it can be seen that the production method of the present application can produce lubricating base oil with low pour point and low aromatic hydrocarbon, and has high total base oil yield and low viscosity index loss, which overcomes the weakness of the traditional metal phosphide catalyst that the base oil produced by hydroprocessing wax oil has high pour point and freezing point, which cannot meet the use requirements.

[0101] The above examples are typical examples listed for detailed description of the technical solutions of the present application, and the protection scope of the present application is subject to the protection scope of the claims and the invention content, and is not limited by the described examples. Simple replacement or change of the present application is still within the protection scope of the present application.

Claims

1. A method for producing a low pour point base oil, comprising: The oil after hydroprocessing is subjected to hydroisomerization reaction under the action of at least one metal phosphide catalyst to obtain low pour point base oil, characterized in that the metal phosphide catalyst comprises a metal component and a carrier, the metal phosphide catalyst is subjected to two modification treatments, the first modification is to introduce a modification aid into the carrier by impregnation to obtain a modified molecular sieve, and the second modification is to prepare a homogeneous solution of the modification aid and a metal component salt, and then impregnate the carrier; The modification aid is a compound of a modification aid metal and / or an acid; the modification aid metal is at least one of Group IA or Group IIA metal; and the acid is at least one of nitric acid, phosphoric acid, acetic acid, tartaric acid, hydrochloric acid, hydrofluoric acid and citric acid; The carrier comprises a molecular sieve, alumina and / or amorphous silica-alumina; The modified molecular sieve is characterized by a pyridine infrared method, the B acid content is 0.1-0.6 mmol / g at 150 DEG C, the molar content ratio of B acid to L acid is 1:2-5:1, the B acid content is 0.05-0.4 mmol / g at 350 DEG C, and the molar content ratio of B acid to L acid is 1:2-5:1; wherein the total acid amount of B acid and L acid at 150 DEG C is greater than the total acid amount of B acid and L acid at 350 DEG C.

2. The method for producing a low pour point base oil according to claim 1, characterized by, The molecular sieve has a ten-membered ring or a twelve-membered ring topological structure and a straight-through pore structure; the molar ratio of Si / Al2O3 in the molecular sieve is 0.1-100, and the average crystal grain size is 30-200 nm.

3. The method for producing a low pour point base oil according to claim 1, characterized by, The molecular sieve is at least one of SAPO-31, SAPO-11, ZSM-22, MCM-22, SAPO-41, ZSM-23, ZSM-35 and ZSM-48.

4. The method for producing a low pour point base oil according to claim 1, characterized by, The modification aid metal is at least one of lithium, sodium, potassium, rubidium, cesium, francium, beryllium, magnesium, calcium, strontium, barium and radium.

5. The method for producing a low pour point base oil according to claim 1, characterized by, The metal component is at least one of nickel, molybdenum and tungsten, and the metal component exists in the metal phosphide catalyst in a combined state; In the metal phosphide catalyst, the phosphorus is at least one of phosphate, phosphoric acid, monohydrogen phosphate, dihydrogen phosphate and hypophosphite; the total content of the metal component and the phosphorus in the metal phosphide catalyst accounts for 10-40 wt% of the mass of the metal phosphide catalyst; and the molar ratio of the phosphorus to the metal component in the metal phosphide catalyst is 1:7-7:

1.

6. The method for producing a low pour point base oil according to claim 5, characterized by, In the metal phosphide catalyst, the total content of the metal component and the phosphorus accounts for 10-30 wt% of the mass of the metal phosphide catalyst; and the molar ratio of the phosphorus to the metal component in the metal phosphide catalyst is 1:5-5:

1.

7. The method for producing a low pour point base oil according to claim 1, characterized by, In the metal phosphide catalyst, the mass ratio of the metal component to the carrier is 1:10-1:1; in the carrier, the mass ratio of the modified molecular sieve to alumina is 2:3-9:1, and the modification aid accounts for 1 wt%-10 wt% of the mass of the metal phosphide catalyst.

8. The method for producing a low pour point base oil according to claim 7, characterized by, In the metal phosphide catalyst, the mass ratio of the metal component to the carrier is 1:9-3:7; and in the carrier, the modification aid accounts for 1 wt%-5 wt% of the mass of the metal phosphide catalyst.

9. The method for producing a low pour point base oil according to claim 1, characterized by, The oil after the hydroprocessing is selected from at least one of hydrocracking tail oil, vacuum second line wax oil, vacuum third line wax oil, and vacuum fourth line wax oil.

10. The method for producing a low pour point base oil according to claim 1, characterized by, The oil after the hydroprocessing has a sulfur content of no more than 200 μg / g and a nitrogen content of no more than 100 μg / g; and a distillation range of 300-600℃.

11. The method for producing a low pour point base oil according to claim 10, characterized by, The oil after the hydroprocessing has a sulfur content of no more than 100 μg / g and a nitrogen content of no more than 50 μg / g.

12. The method for producing a low pour point base oil according to claim 10, characterized by, The oil after the hydroprocessing has a sulfur content of no more than 50 μg / g and a nitrogen content of no more than 30 μg / g.

13. The method for producing a low pour point base oil according to claim 10, characterized by, The oil after the hydroprocessing has a distillation range of 350-580℃.

14. The method of producing a low pour point base oil according to claim 1, characterized by, The temperature of the hydroisomerization reaction is 320-400℃, the volume space velocity is 0.8-2.0h -1 .

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