Hydroisomerization catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of hydroisomerization catalysts, in particular to a hydroisomerization catalyst and a preparation method and application thereof. The method comprises the following steps: (1) mixing a hydrogen type molecular sieve, an aluminum oxide precursor and an acid solution, and performing extrusion molding and roasting to obtain a carrier precursor; (2) putting the carrier precursor into a first impregnation liquid containing a cationic Pt salt, and carrying out first impregnation to obtain a catalyst precursor I; (3) putting the catalyst precursor I into a second impregnation liquid containing alkaline earth metal salt for second impregnation to obtain a catalyst precursor II; and (4) calcining the catalyst precursor II to obtain the hydroisomerization catalyst. The hydroisomerization catalyst prepared by the method provided by the invention has high hydroisomerization activity, and can significantly reduce the cloud point and pour point of the lubricant base oil and greatly improve the low-temperature fluidity of the lubricant base oil while improving the yield of the lubricant base oil.

Description

Technical Field

[0001] The present invention relates to the technical field of hydroisomerization catalysts, and particularly relates to a hydroisomerization catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] A hydroisomerization catalyst is a bifunctional catalyst that can effectively convert n-alkanes into isoalkanes. It has a wide range of applications in reducing low-temperature fluidity indexes such as the pour point, cloud point, and freezing point of lubricating oil base oils.

[0003] A hydroisomerization catalyst generally includes two parts: an acidic active center and a noble metal active center. Among them, the acidic center is usually a one-dimensional mesoporous 10-membered ring zeolite, mainly structures such as ZSM-22, ZSM-23, ZSM-48, SAPO-11, SAPO-31, SAPO-41, etc. These zeolite molecular sieve materials can not only provide acidic active centers to drive the reaction, but also effectively reduce the generation of benzene, naphthenes, and polycyclic aromatic hydrocarbons due to the confinement of the pore mouths and pore channels of these molecular sieves. Thus, the conversion of n-alkanes into isoalkanes can be maximized. Therefore, the low-temperature flow condition of the target product can be improved without significantly reducing the viscosity of the oil product, and the loss of yield can be reduced.

[0004] The noble metal active center mainly provides a medium for the dehydrogenation of n-alkanes to form n-alkenes. After the n-alkenes are subjected to the acidic center and pore mouth confinement of the molecular sieve, unstable isomerized alkenes can be obtained. If the noble metal activity is insufficient, the unstable isomerized alkenes will break, causing cracking and reducing the yield of the target product. Only when the noble metal active center has better hydrogenation activity can the unstable isomerized alkenes form stable isomerized alkanes after hydrogenation, completing the conversion of n-alkanes into isoalkanes.

[0005] The industrial development has higher and higher requirements for the quality of lubricating oil base oils, and the cloud point index of lubricating oil base oils has become a major focus of attention. The cloud point temperature refers to the temperature at which the lubricating oil base oil begins to become turbid.

[0006] When using a hydroisomerization catalyst to catalyze the production of lubricating oil base oils from high-wax crude oil or FT wax raw materials, due to the low reaction temperature and insufficient raw material conversion depth, the content of residual wax in the product is relatively high, the cloud point of the lubricating oil base oil increases, and the product quality does not meet the standards. Although increasing the reaction temperature can increase the conversion depth, increasing the reaction temperature will inevitably lead to an intensification of side reactions. For example, the generation amount of light components increases, and the yield of the lubricating oil base oil decreases, seriously affecting economic benefits.

[0007] To further improve the selectivity of the catalyst for the conversion of n-alkanes to iso-alkanes, people usually adopt the methods of reducing the catalyst activity and improving the hydrogenation performance of noble metals, so as to make the acid centers match the noble metal hydrogenation active centers. Modifying the acid active centers of molecular sieves by means of alkali metals, alkaline earth metals, silanization treatment, etc. is a commonly used method, such as US7141529B2, CN103031144A, CN102049287B, CN105214718B, etc.

[0008] In US7141529B2, a molecular sieve with MTT or TON zeolite structure is formed with substances such as alumina, and after calcination to form a shaped carrier, the shaped carrier is impregnated and modified with a modified metal composed of one or several combinations of Ca, Cr, Mg, La, Ba, Na, Pr, Sr, K, Nd. Then the carrier after the first impregnation is dried. Subsequently, noble metal salts such as Pt or Pd are loaded on the carrier after the first impregnation. After the second impregnation, the carrier is dried and calcined at a temperature not exceeding 593 °C to finally form a catalyst. This technology improves the selectivity of the catalyst by modifying the acidic active centers in the catalyst, and does not involve the description of how to improve the dispersion of noble metals. In actual operation, since the catalyst preparation process first modifies the molecular sieve and alumina carrier with alkaline earth metals and then impregnates with noble metals, it causes the loss of catalyst activity, resulting in a higher reaction temperature of the catalyst, accompanied by more cracking of n-alkanes, reducing the yield of the target product and causing a large amount of energy waste.

[0009] CN103031144A uses small crystal MTT molecular sieves with a size of 20 - 40 nm to form a shape with a refractory inorganic oxide carrier, and after drying and calcination to form carrier particles, the carrier particles are impregnated with at least one of Ca, Cr, Mg, La, Ba, Na, Pr, Sr, K, Nd, and after drying again, metal-modified carrier particles are obtained. Then the metal-modified carrier particles are further impregnated with Group VIII metals, and after drying and calcination, a catalyst is obtained. This catalyst has a good effect on the hydroisomerization of n-alkanes and plays a positive role in obtaining the yield of the target product, which is mainly attributed to the special role of small crystal molecular sieves. In addition, in its patent report, the impregnation process using a solution containing both platinum and magnesium is mentioned, but the patent does not limit the step-by-step impregnation of the impregnation solution process or method, nor does it describe the dispersion of Pt metal.

[0010] A preparation method of a hydroisomerization catalyst with the characteristic of highly dispersed single-atom form is proposed in CN114958423A. Its characteristic is to mix MTT or TON molecular sieve with alumina and acid, extrude and form, and then obtain the catalyst support through drying and calcination. The catalyst support containing noble metal is obtained by impregnating the catalyst support with a solution containing noble metal. After soaking the catalyst support containing noble metal in a solution containing nitrides (mainly ammonia and organic amines), a hydroisomerization catalyst with single-atom dispersion is obtained through high-temperature calcination, which can reduce the noble metal consumption by more than about 50%. However, this method requires a special nitrogen-containing compound as the solution environment during the preparation of the catalyst, and the preparation process is complex. Summary of the Invention

[0011] The object of the present invention is to solve the problem that it is difficult to both reduce the cloud point of lubricating oil base oil and improve the yield of lubricating oil base oil when using a hydroisomerization catalyst to produce lubricating oil base oil, and to provide a hydroisomerization catalyst, its preparation method and application.

[0012] To achieve the above object, the first aspect of the present invention provides a preparation method of a hydroisomerization catalyst, wherein the method comprises the following steps:

[0013] (1) Mix a hydrogen-type molecular sieve, an alumina precursor and an acid solution, then extrude and form and calcine to obtain a support precursor;

[0014] (2) Immerse the support precursor in a first impregnation solution containing a cationic Pt salt for the first impregnation to obtain a catalyst precursor I;

[0015] (3) Immerse the catalyst precursor I in a second impregnation solution containing an alkaline earth metal salt for the second impregnation to obtain a catalyst precursor II;

[0016] (4) Calcine the catalyst precursor II to obtain a hydroisomerization catalyst.

[0017] The second aspect of the present invention provides a hydroisomerization catalyst, wherein, based on the mass of the catalyst, the catalyst comprises 0.3-0.8 wt% of a noble metal active component Pt, 0.5-5 wt% of an alkaline earth metal active component and 94.2-99.4 wt% of a support; wherein, the noble metal active component Pt is dispersed in the support in a single-atom state.

[0018] The third aspect of the present invention provides an application of the hydroisomerization catalyst prepared by using the preparation method described in the first aspect of the present invention or the hydroisomerization catalyst described in the second aspect of the present invention in the production of lubricating oil base oil.

[0019] Through the above technical solutions, the beneficial technical effects achieved by the present invention are as follows:

[0020] 1) In the preparation method of the hydroisomerization catalyst provided by the present invention, a carrier precursor is prepared by using a hydrogen-type molecular sieve with acidity and alumina. First, a cationic Pt salt is impregnated on the carrier precursor, and then an alkaline earth metal salt is impregnated. On the one hand, the alkaline earth metal salt can fill and block the vacancies between Pt atoms dispersed on the carrier in a single-atom state, preventing the agglomeration of the single-atom noble metal Pt during the activation process of calcining to form the catalyst, so that the noble metal Pt in the catalyst remains dispersed in an atomic state. On the other hand, it will not cause a large loss of acidity in the carrier, which is beneficial to improving the activity of the catalyst and maintaining good hydroisomerization selectivity;

[0021] 2) The hydroisomerization catalyst provided by the present invention has high hydroisomerization activity and good selectivity for isomerization products. It can reduce the cloud point and pour point of the lubricating oil base oil, greatly improve the low-temperature fluidity of the lubricating oil base oil, and at the same time significantly increase the yield of the lubricating oil base oil;

[0022] 3) When the hydroisomerization catalyst provided by the present invention is used to prepare the lubricating oil base oil, it can increase the yield of the lubricating oil base oil while reducing the cloud point of the lubricating oil base oil, reduce the production probability and production energy consumption of non-selective target products, and significantly improve the economic benefits. Description of the Drawings

[0023] Figure 1 is the aberration-corrected electron microscopy image of catalyst 1 prepared in Example 1;

[0024] Figure 2 is the aberration-corrected electron microscopy image of catalyst D1 prepared in Comparative Example 1;

[0025] Figure 3 is the aberration-corrected electron microscopy image of catalyst D2 prepared in Comparative Example 2;

[0026] Figure 4 is the aberration-corrected electron microscopy image of catalyst D3 prepared in Comparative Example 3;

[0027] Figure 5 is the H 2 -TPR characterization diagram of the hydroisomerization catalysts prepared in Example 1 and Comparative Example 1. Detailed Embodiments

[0028] The endpoints and any values within the ranges disclosed herein are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range, between the endpoint values and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0029] The first aspect of the present invention provides a method for preparing a hydroisomerization catalyst, wherein the method comprises the following steps:

[0030] (1) Mix a hydrogen-type molecular sieve, an alumina precursor, and an acid solution, then extrude and calcine to obtain a carrier precursor;

[0031] (2) Immerse the carrier precursor in a first impregnation solution containing a cationic Pt salt for the first impregnation to obtain a catalyst precursor I;

[0032] (3) Immerse the catalyst precursor I in a second impregnation solution containing an alkaline earth metal salt for the second impregnation to obtain a catalyst precursor II;

[0033] (4) Calcine the catalyst precursor II to obtain a hydroisomerization catalyst.

[0034] Among them, in the present invention, the inventors have found through research that by using a hydrogen-type molecular sieve with acidity and an alumina precursor to prepare a carrier precursor, first impregnating a cationic Pt salt on the carrier precursor, and then impregnating an alkaline earth metal salt. On the one hand, the alkaline earth metal salt can fill and block the vacancies between Pt atoms dispersed in the form of single atoms on the carrier, avoiding the aggregation of the noble metal Pt in the form of single atoms during the activation process of forming the catalyst by calcination, so that the noble metal Pt in the catalyst can still be dispersed in the form of atoms. On the other hand, it will not cause a large loss of acidity in the carrier, which is beneficial to improving the activity of the catalyst and maintaining good hydroisomerization selectivity.

[0035] In step (1):

[0036] In an embodiment of the present invention, the content of metal cations in the hydrogen-type molecular sieve is ≤100 ppm, preferably ≤50 ppm. Among them, the metal cations in the molecular sieve include but are not limited to Na + and / or K + .

[0037] In an embodiment of the present invention, the silica-alumina ratio of the hydrogen-type molecular sieve is 50-100, preferably 70-80.

[0038] In one embodiment of the present invention, the hydrogen-form molecular sieve is selected from hydrogen-form MTT molecular sieve and / or hydrogen-form TON molecular sieve, preferably selected from one or more of hydrogen-form ZSM-22, hydrogen-form ZSM-23, hydrogen-form SSZ-32, and hydrogen-form Theta-1, and preferably is hydrogen-form ZSM-22 and / or hydrogen-form ZSM-23.

[0039] In one embodiment of the present invention, the preparation method of the hydrogen-form molecular sieve includes: treating the molecular sieve at 450 - 650 °C for 1 - 5 h and then performing ion exchange with an inorganic ammonium salt to obtain the hydrogen-form molecular sieve; wherein, the molecular sieve is selected from MTT molecular sieve and / or TON molecular sieve, and further selected from one or more of ZSM-22, ZSM-23, SSZ-32, and Theta-1; the inorganic ammonium salt is selected from one or more of ammonium nitrate, ammonium sulfate, and ammonium chloride.

[0040] Among them, in the present invention, the hydrogen-form molecular sieve has acidity and can be a commercially available product, or can be prepared according to the method of ion-exchanging MTT molecular sieve and / or TON molecular sieve with common inorganic ammonium salt substances such as ammonium nitrate, ammonium sulfate, and ammonium chloride well-known in the art. MTT molecular sieve and TON molecular sieve can be commercially available products, or can be prepared according to the methods well-known in the art. For example, MTT molecular sieve can be synthesized with reference to "A method for synthesizing MTT zeolite molecular sieve with a short-axis morphology" disclosed in CN110683558B. TON molecular sieve can be synthesized with reference to "A stable synthesis method of TON zeolite" in CN106853972B.

[0041] In one embodiment of the present invention, the alumina precursor is selected from one or more of pseudoboehmite, activated alumina, and aluminum sol, and preferably is pseudoboehmite.

[0042] In one embodiment of the present invention, the acid solution is dilute nitric acid. Among them, the concentration of the dilute nitric acid can be 1 - 10 wt%, and preferably is 3 - 5 wt%.

[0043] Among them, in the present invention, the amount of the acid solution used in the present invention is not specifically limited, and it can be added according to the conventional addition amount in the art. For example, based on 90 g of the hydrogen-form molecular sieve, the addition amount of the dilute nitric acid can be 45 - 65 g.

[0044] In one embodiment of the present invention, the feeding amounts of the hydrogen-form molecular sieve and the alumina precursor are such that in the catalyst prepared, based on the mass of the carrier, it includes 50 - 80 wt%, preferably 60 - 75 wt% of the molecular sieve and 20 - 50 wt%, preferably 25 - 40 wt% of the alumina.

[0045] Among them, in the present invention, the contents of molecular sieve and alumina in the carrier can be calculated according to the feeding amount during the preparation process. Among them, the hydrogen-type molecular sieve added during the preparation process is recorded as molecular sieve after being prepared into a catalyst, and the mass of the molecular sieve in the catalyst is equal to the feeding amount of the hydrogen-type molecular sieve.

[0046] In one embodiment of the present invention, the operating conditions of the calcination include: the calcination temperature is 250 - 450 °C, preferably 300 - 400 °C; the calcination time is 2 - 10 h, preferably 3 - 6 h.

[0047] In step (2):

[0048] In one embodiment of the present invention, the cationic Pt salt is selected from one or more of tetraammineplatinum(II) acetate, tetraammineplatinum(II) nitrate, tetraammineplatinum(II) nitrite, tetraammineplatinum(II) sulfate, and tetraammineplatinum(II) chloride, and preferably tetraammineplatinum(II) nitrate.

[0049] In one embodiment of the present invention, the feeding amount of the cationic Pt salt is such that the prepared catalyst contains 0.3 - 0.8 wt%, preferably 0.35 - 0.45 wt% of the noble metal active component Pt based on the mass of the catalyst.

[0050] In one embodiment of the present invention, the feeding amount of the carrier precursor is such that the prepared catalyst contains 94.2 - 99.4 wt%, preferably 95 - 98 wt% of the carrier based on the mass of the catalyst.

[0051] In one embodiment of the present invention, the first impregnation is isovolumetric impregnation, carried out under vacuum, and the impregnation temperature is 20 - 100 °C, preferably 60 - 80 °C.

[0052] In one embodiment of the present invention, after the first impregnation, drying is carried out to obtain catalyst precursor I. Among them, in the present invention, the drying temperature can be 100 - 150 °C.

[0053] In step (3):

[0054] In one embodiment of the present invention, the alkaline earth metal salt is selected from one or more of calcium nitrate, calcium sulfate, calcium chloride, magnesium nitrate, magnesium sulfate, and magnesium chloride, and preferably calcium nitrate and / or magnesium nitrate.

[0055] In one embodiment of the present invention, the feeding amount of the alkaline earth metal salt is such that the prepared catalyst contains 0.5 - 5 wt%, preferably 2 - 4 wt% of the alkaline earth metal active component based on the mass of the catalyst.

[0056] In one embodiment of the present invention, the second impregnation is equal-volume impregnation, carried out under vacuum, and the impregnation temperature is 20 - 100 °C, preferably 60 - 80 °C.

[0057] In one embodiment of the present invention, after the second impregnation, drying is carried out to obtain the catalyst precursor II.

[0058] In step (4):

[0059] In one embodiment of the present invention, the operating conditions of the calcination include: the calcination temperature is 250 - 450 °C, preferably 300 - 400 °C; the calcination time is 2 - 10 h, preferably 3 - 6 h.

[0060] Among them, in the present invention, if the calcination temperature is too high, agglomeration of Pt metal is likely to occur; if the calcination temperature is too low, the metal salt cannot be effectively decomposed, and it is difficult to form effective active substances during subsequent treatment. When the calcination temperature is within the above-defined range, the active component Pt can be dispersed on the carrier in a single-atom state, and the activity of the catalyst is better.

[0061] The second aspect of the present invention provides a hydroisomerization catalyst, wherein, based on the mass of the catalyst, the catalyst comprises 0.3 - 0.8 wt% of the noble metal active component Pt, 0.5 - 5 wt% of the alkaline earth metal active component, and 94.2 - 99.4 wt% of the carrier; wherein, the noble metal active component Pt is dispersed on the carrier in a single-atom state.

[0062] Among them, in the present invention, the contents of the noble metal active component and the alkaline earth metal active component are calculated based on the corresponding metal oxides, and the contents of the noble metal active component, the alkaline earth metal active component, and the carrier in the hydroisomerization catalyst are calculated according to the feeding amounts.

[0063] In one embodiment of the present invention, the content of the noble metal active component Pt can be 0.3 wt%, 0.35 wt%, 0.4 wt%, 0.45 wt%, 0.5 wt%, 0.55 wt%, 0.6 wt%, 0.65 wt%, 0.7 wt%, 0.75 wt%, 0.8 wt%, and any value among these values, preferably 0.35 - 0.45 wt%.

[0064] In one embodiment of the present invention, the content of the alkaline earth metal active component can be 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, and any value among these values, preferably 2 - 4 wt%.

[0065] In one embodiment of the present invention, the content of the carrier may be 94.2 wt%, 94.6 wt%, 95 wt%, 95.3 wt%, 95.5 wt%, 95.8 wt%, 96 wt%, 96.3 wt%, 96.5 wt%, 96.8 wt%, 97 wt%, 97.3 wt%, 97.5 wt%, 97.7 wt%, 98 wt%, 98.3 wt%, 98.5 wt%, 99 wt%, 99.4 wt%, and any value among these values, preferably 95 - 98 wt%.

[0066] In one embodiment of the present invention, the alkaline earth metal active component is Mg and / or Ca. Among them, in the present invention, when the alkaline earth metal active component is Mg and / or Ca, the hydroisomerization activity of the hydroisomerization catalyst is better.

[0067] In one embodiment of the present invention, based on the mass of the carrier, the carrier comprises 50 - 80 wt%, preferably 60 - 75 wt% of molecular sieve and 20 - 50 wt%, preferably 25 - 40 wt% of alumina.

[0068] In one embodiment of the present invention, the silica-alumina ratio of the molecular sieve is 50 - 100, preferably 70 - 80.

[0069] In one embodiment of the present invention, the molecular sieve is selected from MTT molecular sieve and / or TON molecular sieve, preferably selected from one or more of ZSM-22, ZSM-23, SSZ-32, Theta-1.

[0070] The third aspect of the present invention provides an application of the hydroisomerization catalyst prepared by the preparation method described in the first aspect of the present invention or the hydroisomerization catalyst described in the second aspect of the present invention in the production of lubricating base oil.

[0071] Among them, for the hydroisomerization catalyst provided in the present invention, the noble metal active component Pt is dispersed on the carrier in a single-atom state, which can effectively improve the dispersion degree of the noble metal in the hydroisomerization catalyst and the activity of the hydroisomerization catalyst, can effectively improve the low-temperature fluidity of the isomerization product, and can improve the pour point and cloud point of the lubricating base oil while increasing the yield of the lubricating base oil.

[0072] The present invention will be described in detail below through examples.

[0073] Example 1

[0074] (1) Refer to the method described in Example 2 of CN110683558B to prepare ZSM-23 molecular sieve with a silica-alumina ratio of 70; calcine the ZSM-23 molecular sieve at 550 °C for 3 h and then perform two exchanges with ammonium nitrate to obtain acidic hydrogen-type ZSM-23 molecular sieve; wherein, Na + content < 100 ppm;

[0075] Mix 90 g of the above hydrogen-type ZSM-23 molecular sieve, 40 g of SB powder (Al 2 O 3 content is 75 wt%) with 57 g of a dilute nitric acid solution with a mass content of 4.5%, then roll and extrude into shape, dry at 120 °C, and calcine at 350 °C for 6 h to obtain a carrier precursor;

[0076] (2) Under vacuum conditions, use an aqueous solution of tetraammineplatinum nitrate as the first impregnation solution, put the above carrier precursor into the first impregnation solution, perform the first equal-volume impregnation at 70 °C, and dry at 120 °C to obtain catalyst precursor I;

[0077] (3) Under vacuum conditions, use an aqueous solution of magnesium nitrate as the second impregnation solution, put the above catalyst precursor I into the second impregnation solution, perform the second equal-volume impregnation at 70 °C, and dry at 120 °C to obtain catalyst precursor II;

[0078] (4) Calcinate the above catalyst precursor II at 350 °C for 6 h to obtain a hydroisomerization catalyst 1.

[0079] Among them, calculated according to the feed amount, in the hydroisomerization catalyst 1, it includes 0.45 wt% of the noble metal active component Pt, 2.2 wt% of the alkaline earth metal active component Mg, and 97.35 wt% of the carrier; among them, the carrier contains 75 wt% of ZSM-23 molecular sieve and 25 wt% of alumina.

[0080] Example 2

[0081] (1) Refer to the method described in Example 2 of CN110683558B to prepare ZSM-23 molecular sieve with a silica-alumina ratio of 70; treat the ZSM-23 molecular sieve at 550 °C for 3 h and then perform two exchanges with ammonium nitrate to obtain acidic hydrogen-type ZSM-23 molecular sieve; wherein, Na + content < 100 ppm;

[0082] Mix 90 g of the above hydrogen-type ZSM-23 molecular sieve, 80 g of SB powder (Al 2 O 3Mix 75 wt% of it with 50 g of dilute nitric acid solution with a mass content of 4%, then carry out rolling and extrusion molding, dry at 120 °C, and calcine at 400 °C for 6 h to obtain a carrier precursor;

[0083] (2) Under vacuum conditions, use an aqueous solution of tetraammineplatinum nitrate as the first impregnation solution. Put the above carrier precursor into the first impregnation solution, carry out the first equal-volume impregnation at 70 °C, and dry at 120 °C to obtain catalyst precursor I;

[0084] (3) Under vacuum conditions, use an aqueous solution of magnesium nitrate as the second impregnation solution. Put the above catalyst precursor I into the second impregnation solution, carry out the second equal-volume impregnation at 70 °C, and dry at 120 °C to obtain catalyst precursor II;

[0085] (4) Calcinate the above catalyst precursor II at 400 °C for 6 h to obtain a hydroisomerization catalyst 2.

[0086] Among them, calculated according to the feeding amount, in the hydroisomerization catalyst 2, it includes 0.4 wt% of noble metal active component Pt, 3.0 wt% of alkaline earth metal active component Mg, and 96.6 wt% of the carrier; among them, the carrier contains 60 wt% of ZSM-23 molecular sieve and 40 wt% of alumina.

[0087] Example 3

[0088] (1) Refer to the method described in Example 2 of CN110683558B to prepare a ZSM-23 molecular sieve with a silica-alumina ratio of 70; treat the ZSM-23 molecular sieve at 550 °C for 3 h and then carry out two exchanges with ammonium nitrate to obtain a hydrogen-type ZSM-23 molecular sieve with acidity; among them, Na + content < 100 ppm;

[0089] Mix 90 g of the above hydrogen-type ZSM-23 molecular sieve, 80 g of SB powder (Al 2 O 3 content is 75 wt%) with 50 g of dilute nitric acid solution with a mass content of 4%, then carry out rolling and extrusion molding, dry at 120 °C, and calcine at 300 °C for 4 h to obtain a carrier precursor;

[0090] (2) Under vacuum conditions, use an aqueous solution of tetraammineplatinum nitrate as the first impregnation solution. Put the above carrier precursor into the first impregnation solution, carry out the first equal-volume impregnation at 60 °C, and dry at 120 °C to obtain catalyst precursor I;

[0091] (3) Under vacuum conditions, using an aqueous solution of magnesium nitrate as the second impregnation solution, put the above catalyst precursor I into the second impregnation solution, conduct the second equal-volume impregnation at 60 °C, and dry at 120 °C to obtain catalyst precursor II;

[0092] (4) Calcinate the above catalyst precursor II at 300 °C for 4 h to obtain the hydroisomerization catalyst 3.

[0093] Among them, calculated according to the feed amount, in the hydroisomerization catalyst 3, it includes 0.35 wt% of the noble metal active component Pt, 4.0 wt% of the alkaline earth metal active component Mg, and 95.65 wt% of the carrier; among them, the carrier contains 60 wt% of ZSM-23 molecular sieve and 40 wt% of alumina.

[0094] Example 4

[0095] (1) Refer to the method described in Example 2 of CN106853972B to prepare a ZSM-22 molecular sieve with a silica-alumina ratio of 80; treat the ZSM-22 molecular sieve at 550 °C for 3 h and then conduct two exchanges with ammonium nitrate to obtain a hydrogen-type ZSM-22 molecular sieve with acidity; among them, the K + content < 100 ppm;

[0096] Mix 90 g of the above hydrogen-type ZSM-22 molecular sieve, 80 g of SB powder (Al 2 O 3 content is 75 wt%) and 57 g of a dilute nitric acid solution with a mass content of 4.5%, then conduct rolling and extrusion molding, dry at 120 °C, and calcine at 300 °C for 6 h to obtain a carrier precursor;

[0097] (2) Under vacuum conditions, using an aqueous solution of tetraammineplatinum nitrate as the first impregnation solution, put the above carrier precursor into the first impregnation solution, conduct the first equal-volume impregnation at 80 °C, and dry at 120 °C to obtain catalyst precursor I;

[0098] (3) Under vacuum conditions, using an aqueous solution of calcium nitrate as the second impregnation solution, put the above catalyst precursor I into the second impregnation solution, conduct the second equal-volume impregnation at 80 °C, and dry at 120 °C to obtain catalyst precursor II;

[0099] (4) Calcinate the above catalyst precursor II at 300 °C for 6 h to obtain the hydroisomerization catalyst 4.

[0100] Among them, calculated according to the feeding amount, in the hydroisomerization catalyst 4, it includes 0.35 wt% of the noble metal active component Pt, 4.0 wt% of the alkaline earth metal active component Ca, and 95.65 wt% of the carrier; among them, the carrier contains 60 wt% of ZSM-22 molecular sieve and 40 wt% of alumina.

[0101] Comparative Example 1:

[0102] Same as Example 1, the difference is that magnesium nitrate is impregnated first and then tetraammineplatinum nitrate is impregnated, specifically as follows:

[0103] (1) Referring to the method described in Example 2 of CN110683558B, prepare ZSM-23 molecular sieve with a silica-alumina ratio of 70; treat the ZSM-23 molecular sieve at 550 °C for 3 h and then perform two exchanges with ammonium nitrate to obtain acidic hydrogen-type ZSM-23 molecular sieve; among them, Na + content < 100 ppm;

[0104] Mix 90 g of the above-mentioned hydrogen-type ZSM-23 molecular sieve, 40 g of SB powder (Al 2 O 3 content is 75 wt%) with 57 g of a dilute nitric acid solution with a mass content of 4.5%, then roll and extrude into shape, dry at 120 °C, and calcine at 350 °C for 6 h to obtain a carrier precursor;

[0105] (2) Under vacuum conditions, use an aqueous solution of magnesium nitrate as the first impregnation solution, put the above-mentioned carrier precursor into the first impregnation solution, perform the first equal-volume impregnation at 70 °C, and dry at 120 °C to obtain catalyst precursor I;

[0106] (3) Under vacuum conditions, use an aqueous solution of tetraammineplatinum nitrate as the second impregnation solution, put the above-mentioned catalyst precursor I into the second impregnation solution, perform the second equal-volume impregnation at 70 °C, and dry at 120 °C to obtain catalyst precursor II;

[0107] (4) Calcinate the above-mentioned catalyst precursor II at 350 °C for 6 h to obtain the hydroisomerization catalyst D1.

[0108] Among them, calculated according to the feeding amount, in the hydroisomerization catalyst D1, it includes 0.45 wt% of the noble metal active component Pt, 2.2 wt% of the alkaline earth metal active component Mg, and 97.35 wt% of the carrier; among them, the carrier contains 75 wt% of ZSM-23 molecular sieve and 25 wt% of alumina.

[0109] Comparative Example 2:

[0110] Same as Example 1, the difference is that tetraammineplatinum nitrate and magnesium nitrate are impregnated together, specifically as follows:

[0111] (1) Refer to the method described in Example 2 of CN110683558B to prepare ZSM-23 molecular sieve with a silica-alumina ratio of 70; treat the ZSM-23 molecular sieve at 550 °C for 3 h and then perform two exchanges with ammonium nitrate to obtain acidic hydrogen-type ZSM-23 molecular sieve; wherein, the Na + content < 100 ppm;

[0112] Mix 90 g of the above hydrogen-type ZSM-23 molecular sieve, 40 g of SB powder (Al 2 O 3 content is 75 wt%) with 57 g of dilute nitric acid solution with a mass content of 4.5%, then perform rolling and extrusion molding, dry at 120 °C, and calcine at 350 °C for 6 h to obtain a carrier precursor;

[0113] (2) Under vacuum conditions, use an aqueous solution of tetraammineplatinum nitrate and magnesium nitrate as the impregnation solution, put the above carrier precursor into the impregnation solution, perform equal-volume impregnation at 70 °C, and dry at 120 °C to obtain a catalyst precursor;

[0114] (3) Calcinate the above catalyst precursor at 350 °C for 6 h to obtain the hydroisomerization catalyst D2.

[0115] Among them, calculated according to the feeding amount, in the hydroisomerization catalyst D2, it includes 0.45 wt% of the noble metal active component Pt, 2.2 wt% of the alkaline earth metal active component Mg, and 97.35 wt% of the carrier; among them, the carrier contains 75 wt% of ZSM-23 molecular sieve and 25 wt% of alumina.

[0116] Comparative Example 3:

[0117] Same as Example 1, the difference is that the impregnation of magnesium nitrate is omitted, specifically as follows:

[0118] (1) Refer to the method described in Example 2 of CN110683558B to prepare ZSM-23 molecular sieve with a silica-alumina ratio of 70; treat the ZSM-23 molecular sieve at 550 °C for 3 h and then perform two exchanges with ammonium nitrate to obtain acidic hydrogen-type ZSM-23 molecular sieve; wherein, the Na + content < 100 ppm;

[0119] Mix 90 g of the above hydrogen-type ZSM-23 molecular sieve, 40 g of SB powder (Al 2 O 3 content is 75 wt%) with 57 g of dilute nitric acid solution with a mass content of 4.5%, then perform rolling and extrusion molding, dry at 120 °C, and calcine at 350 °C for 6 h to obtain a carrier precursor;

[0120] (2) Under vacuum conditions, using an aqueous solution of tetraammineplatinum nitrate as the first impregnation solution, the above-mentioned carrier precursor is placed in the first impregnation solution, and the first equal-volume impregnation is carried out at 70 °C and dried at 120 °C to obtain catalyst precursor I;

[0121] (4) The above-mentioned catalyst precursor I is calcined at 350 °C for 6 h to obtain the hydroisomerization catalyst D3.

[0122] Among them, calculated according to the feeding amount, in the hydroisomerization catalyst D3, it includes 0.45 wt% of the noble metal active component Pt and 99.55 wt% of the carrier; among them, the carrier contains 75 wt% of ZSM-23 molecular sieve and 25 wt% of alumina.

[0123] Test Example 1

[0124] The hydroisomerization catalysts prepared in Example 1 and Comparative Examples 1-3 were characterized by aberration-corrected electron microscopy, and the results are as Figures 1-4 shown. Among them, Figure 1 is the aberration-corrected electron microscopy image of catalyst 1 prepared in Example 1. It can be seen from Figure 1 that the platinum metal (bright spots in the picture) in catalyst 1 is basically distributed in a single-atom state.

[0125] Figure 2 is the aberration-corrected electron microscopy image of catalyst D1 prepared in Comparative Example 1. It can be seen from Figure 2 that catalyst D1 contains a large number of 2-4 nm platinum metal clusters. Figure 3 is the aberration-corrected electron microscopy image of catalyst D2 prepared in Comparative Example 2. It can be seen from Figure 3 that catalyst D2 contains a certain amount of 2-4 nm platinum metal clusters. Figure 4 is the aberration-corrected electron microscopy image of catalyst D3 prepared in Comparative Example 3. It can be seen from Figure 4 that in catalyst D3, the Pt metal is basically all 2-4 nm platinum metal clusters, and there is basically no Pt metal in single-atom dispersion.

[0126] Test Example 2

[0127] The hydroisomerization catalysts prepared in Example 1 and Comparative Example 1 were characterized by H 2 -TPR, and the results are as Figure 5 shown. It can be seen from Figure 5 that the temperature at which the reduction peak of the hydroisomerization catalyst 1 with a single-atom dispersion state appears is about 20 °C higher than the temperature at which the reduction peak in the hydroisomerization catalyst D1 appears, indicating that the reduction of Pt atoms in the hydroisomerization catalyst 1 is more difficult and the interaction with the carrier is stronger, thus proving that Pt in the hydroisomerization catalyst 1 has better stability and dispersion state.

[0128] Test Example 3

[0129] Using the product after high-wax hydrofining of the fourth fraction of Daqing crude oil as the raw material, the catalytic activity of the hydroisomerization catalysts prepared in Examples 1-4 and Comparative Examples 1-3 was evaluated using an isothermal fixed-bed reactor. By adjusting the reaction temperature, the cloud points of the lubricating base oils were made substantially similar. Among them, the properties of the raw material products are shown in Table 1, and the evaluation conditions and evaluation results are shown in Table 2.

[0130] Table 1

[0131] Pour point, °C 59 Total sulfur content, μg / g ＜2 Total nitrogen content, μg / g ＜1 <![CDATA[Kinematic viscosity (100 °C), mm 2 / s]]> 9.820 Viscosity index 143 Distillation range, °C 5％ 443 10％ 477 30％ 518 50％ 532 70％ 543 90％ 566 Final boiling point 596

[0132] Table 2

[0133]

[0134]

[0135] As can be seen from Table 2, the catalysts prepared in Examples 1-4 of the present invention have excellent hydroisomerization dewaxing ability, can significantly increase the C5+ liquid yield and the yield of lubricating base oil while reducing the cloud point of the lubricating base oil, and can also significantly reduce the pour point of the lubricating base oil, increase the kinematic viscosity of the lubricating base oil, and greatly improve the low-temperature fluidity of the lubricating base oil.

[0136] From the test results of Comparative Example 1, it can be seen that the catalyst D1 prepared by the method of impregnating Pt first and then Mg in Comparative Example 1 can obtain a lubricating base oil with a lower cloud point when reacting at 390°C. However, compared with Example 1, the C5+ liquid yield and the yield of lubricating base oil in Comparative Example 1 decreased significantly, and the kinematic viscosity of the lubricating base oil was also relatively low.

[0137] From the test results of Comparative Example 2, it can be seen that the catalyst D2 prepared by the method of co-impregnating Pt and Mg in Comparative Example 2 can obtain a lubricating base oil with a lower cloud point when reacting at 383°C. However, compared with Example 1, the C5+ liquid yield and the yield of lubricating base oil in Comparative Example 2 decreased significantly, and the loss of heavy base oil fraction in the feedstock oil was large, resulting in poor economic efficiency.

[0138] From the test results of Comparative Example 3, it can be seen that the catalyst D3 prepared by omitting Mg in Comparative Example 3 can obtain a lubricating base oil with a cloud point of -4°C. However, compared with Example 1, the C5+ liquid yield and the yield of lubricating base oil in Comparative Example 3 decreased significantly, and the loss of heavy base oil fraction in the feedstock oil was large, resulting in poor economic efficiency. Moreover, the pour point and viscosity index of the lubricating base oil in Comparative Example 3 were high, the kinematic viscosity was small, and the low-temperature fluidity was poor.

[0139] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A preparation method of a hydroisomerization catalyst, characterized in that, the method comprises the following steps: (1) Mix a hydrogen-type molecular sieve, an alumina precursor and an acid solution, then carry out extrusion molding and calcination to obtain a carrier precursor; (2) Immerse the carrier precursor in a first impregnation solution containing a cationic Pt salt for the first impregnation to obtain a catalyst precursor I; (3) Immerse the catalyst precursor I in a second impregnation solution containing an alkaline earth metal salt for the second impregnation to obtain a catalyst precursor II; (4) Calcinate the catalyst precursor II to obtain a hydroisomerization catalyst.

2. The preparation method according to claim 1, wherein, The content of metal cations in the hydrogen form molecular sieve ≤ 100 ppm; wherein, the metal cations include Na + and / or K + ; and / or, the silica-alumina ratio of the hydrogen-type molecular sieve is 50 - 100; and / or, the hydrogen-type molecular sieve is selected from a hydrogen-type MTT molecular sieve and / or a hydrogen-type TON molecular sieve.

3. The preparation method according to claim 2, wherein, the hydrogen-type molecular sieve is selected from one or more of a hydrogen-type ZSM-22, a hydrogen-type ZSM-23, a hydrogen-type SSZ-32, and a hydrogen-type Theta-1.

4. The preparation method according to claim 1, wherein, the alumina precursor is selected from one or more of pseudoboehmite, activated alumina, and aluminum sol; and / or, the feeding amounts of the hydrogen-type molecular sieve and the alumina precursor are such that in the catalyst prepared, based on the mass of the carrier, it includes 50 - 80 wt%, preferably 60 - 75 wt% of the molecular sieve and 20 - 50 wt%, preferably 25 - 40 wt% of the alumina.

5. The preparation method according to claim 1, wherein, the operating conditions of the calcination include: the calcination temperature is 250 - 450 °C, preferably 300 - 400 °C; the calcination time is 2 - 10 h, preferably 3 - 6 h.

6. The preparation method according to claim 1, wherein, the cationic Pt salt is selected from one or more of tetraammineplatinum(II) acetate, tetraammineplatinum(II) nitrate, tetraammineplatinum(II) nitrite, tetraammineplatinum(II) sulfate, and tetraammineplatinum(II) chloride; and / or, the feeding amount of the cationic Pt salt is such that in the catalyst prepared, based on the mass of the catalyst, it contains 0.3 - 0.8 wt%, preferably 0.35 - 0.45 wt% of the noble metal active component Pt; and / or, the feeding amount of the carrier precursor is such that in the catalyst prepared, based on the mass of the catalyst, it contains 94.2 - 99.4 wt%, preferably 95 - 98 wt% of the carrier; and / or, the first impregnation is an equal-volume impregnation, carried out under vacuum, and the impregnation temperature is 20 - 100 °C.

7. The preparation method according to claim 1, wherein, the alkaline earth metal salt is selected from one or more of calcium nitrate, calcium sulfate, calcium chloride, magnesium nitrate, magnesium sulfate, and magnesium chloride; and / or, the feeding amount of the alkaline earth metal salt is such that in the catalyst prepared, based on the mass of the catalyst, it contains 0.5 - 5 wt%, preferably 2 - 4 wt% of the alkaline earth metal active component; and / or, the second impregnation is an equal-volume impregnation, carried out under vacuum, and the impregnation temperature is 20 - 100 °C.

8. The preparation method according to claim 1, wherein, the operating conditions of the calcination include: the calcination temperature is 250 - 450 °C, preferably 300 - 400 °C; the calcination time is 2 - 10 h, preferably 3 - 6 h.

9. A hydroisomerization catalyst, characterized in that, based on the mass of the catalyst, the catalyst comprises 0.3 - 0.8 wt% of the noble metal active component Pt, 0.5 - 5 wt% of the alkaline earth metal active component, and 94.2 - 99.4 wt% of the carrier; wherein, the noble metal active component Pt is dispersed on the carrier in a single - atom state.

10. The catalyst according to claim 9, wherein, the alkaline earth metal active component is Mg and / or Ca; and / or, based on the mass of the carrier, the carrier comprises 50 - 80 wt%, preferably 60 - 75 wt% of molecular sieve and 20 - 50 wt%, preferably 25 - 40 wt% of alumina.

11. The catalyst according to claim 10, wherein, the molecular sieve is selected from MTT molecular sieve and / or TON molecular sieve.

12. The catalyst according to claim 11, wherein, the molecular sieve is selected from one or more of ZSM - 22, ZSM - 23, SSZ - 32, Theta - 1.

13. The application of the catalyst prepared by the method according to any one of claims 1 - 8 or the catalyst according to claims 9 - 12 in the production of lubricating base oil.

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