Hydroisomerization catalyst, and preparation method therefor and use thereof

Abstract

A hydroisomerization catalyst, and a preparation method therefor and the use thereof. The preparation method comprises the following steps: (1) mixing a hydrogen-type molecular sieve, an aluminum oxide precursor and an acid solution, and subjecting the resulting mixture to extrusion molding and roasting, so as to obtain a carrier precursor; (2) putting the carrier precursor into a first impregnation liquid containing a cationic Pt salt for first impregnation, so as to obtain a catalyst precursor I; (3) putting the catalyst precursor I into a second impregnation liquid containing an alkaline earth metal salt for secondary impregnation, so as to obtain a catalyst precursor II; and (4) calcining the catalyst precursor II, so as to obtain a hydroisomerization catalyst. The hydroisomerization catalyst obtained by using the preparation method has a high hydroisomerization activity, and can substantially reduce the cloud point and the pour point of a lubricant base oil while increasing the yield of the lubricant base oil, thereby greatly improving the low-temperature fluidity of the lubricant base oil.

Description

Hydroisomerization catalyst and its preparation method and application

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application 202311626936.0 filed on November 30, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to the technical field of hydroisomerization catalysts, and in particular to a hydroisomerization catalyst and a preparation method and application thereof. Background Art

[0004] Hydroisomerization catalysts are bifunctional catalysts that can effectively convert normal paraffins to isoparaffins. They are widely used to improve the low-temperature fluidity properties of lubricating base oils, such as the pour point, cloud point, and other low-temperature fluidity properties.

[0005] Hydroisomerization catalysts generally consist of two components: an acidic active center and a precious metal active center. The acidic center is typically a one-dimensional, mesoporous, 10-membered ring zeolite, primarily in structures such as ZSM-22, ZSM-23, ZSM-48, SAPO-11, SAPO-31, and SAPO-41. These zeolite molecular sieve materials not only provide the acidic active center to drive the reaction, but also, due to the constrained nature of their pores and channels, effectively reduce the production of benzene, cycloalkanes, and polycyclic aromatic hydrocarbons, thereby maximizing the conversion of normal paraffins to isoalkanes. This improves the low-temperature flow properties of the target product and minimizes yield loss, while maintaining minimal reduction in oil viscosity.

[0006] Noble metal active centers primarily serve as a catalyst for the dehydrogenation of n-alkanes to n-olefins. After being constrained by the acidic centers and pore openings of the molecular sieve, n-olefins can yield unstable isomerized olefins. If the noble metal activity is insufficient, the unstable isomerized olefins will break down, causing cracking and reducing the yield of the target product. Only when the noble metal active centers possess enhanced hydrogenation activity can unstable isomerized olefins be hydrogenated to form stable isomerized alkanes, completing the conversion of n-alkanes to isoalkanes.

[0007] Industrial development is placing increasingly stringent demands on the quality of lubricant base oils, and the cloud point of lubricant base oils has become a major focus. The cloud point temperature refers to the highest temperature at which a lubricant base oil begins to become turbid under normal pressure.

[0008] When using hydroisomerization catalysts to produce lubricant base oils from high-wax crude oils or FT wax feedstocks, low reaction temperatures and insufficient feedstock conversion depth result in high residual wax content, elevated cloud points, and substandard product quality. While increasing reaction temperature can increase conversion depth, this inevitably leads to more severe side reactions, such as an increase in light components (e.g., gas and naphtha), a decrease in lubricant base oil yield, and a significant impact on economic efficiency.

[0009] To further improve the catalyst's selectivity for the conversion of normal paraffins to isoparaffins, researchers typically reduce the catalyst's cracking activity and enhance the precious metal's hydrogenation performance, thereby aligning the acid sites with the precious metal's hydrogenation activity. Modifying the acid sites of molecular sieves with alkali metals, alkaline earth metals, or silanization is a common method, as described in US7141529B2, CN103031144A, CN102049287B, and CN105214718B.

[0010] US7141529B2 uses MTT or TON zeolite-structured molecular sieves and alumina to form a shaped support. After calcination to form a shaped support, the shaped support is then impregnated with one or a combination of modifying metals selected from the group consisting of Ca, Cr, Mg, La, Ba, Na, Pr, Sr, K, and Nd. The impregnated support is then dried. The impregnated support is then loaded with a precious metal salt such as Pt or Pd. After a second impregnation, the support is dried and calcined at no more than 593°C to form the catalyst. This technology improves catalyst selectivity by modifying the acidic active centers in the catalyst and does not describe how to improve precious metal dispersion. In practice, since the catalyst preparation process first modifies the molecular sieve and alumina support with alkaline earth metals and then impregnates the support with precious metals, this results in a loss of catalyst activity and a decrease in precious metal dispersion, leading to higher catalyst reaction temperatures and the cracking of more normal alkanes, reducing the yield of the target product and wasting significant energy.

[0011] CN103031144A uses a 20-40 nm small-grain MTT molecular sieve and a refractory inorganic oxide support to form a mold. After drying and calcination, the support particles are formed. At least one of Ca, Cr, Mg, La, Ba, Na, Pr, Sr, K, and Nd is impregnated, and the metal-modified support particles are obtained after drying. The metal-modified support particles are further impregnated with a Group VIII metal, and after drying and calcination, a catalyst is obtained. The catalyst has a good effect on the hydroisomerization of normal alkanes and plays a positive role in obtaining the target product yield, which is mainly attributed to the special effect of the small-grain molecular sieve. In addition, the patent report mentions the impregnation process using a mixed solution containing both platinum and magnesium, but the patent does not define the impregnation solution process or method as a step-by-step impregnation, nor does it describe the dispersion of Pt metal.

[0012] CN114958423A proposes a method for preparing a hydroisomerization catalyst with highly dispersed monatomic forms. This method involves mixing an MTT or TON molecular sieve with alumina and an acid, extruding it into a mold, and then drying and calcining it to obtain a catalyst support. This catalyst support is then impregnated with a solution containing a precious metal to obtain a catalyst support containing the precious metal. This catalyst support containing the precious metal is then immersed in a solution containing a nitride (primarily ammonia and organic amines) and calcined at high temperature to obtain a hydroisomerization catalyst with highly dispersed monatomic forms, which can reduce the amount of precious metal used by approximately 50%. However, this method requires the use of a special nitrogen-containing compound as the solution environment for the catalyst preparation, making the preparation process complex.

[0013] Summary of the Invention

[0014] The purpose of the present invention is to solve the problem of difficulty in simultaneously lowering the cloud point of lubricating base oil and improving the yield of lubricating base oil when lubricating base oil is produced using a hydroisomerization catalyst, and to provide a hydroisomerization catalyst and its preparation method and application.

[0015] In order to achieve the above object, the first aspect of the present invention provides a method for preparing a hydroisomerization catalyst, wherein the method comprises the following steps:

[0016] (1) mixing a hydrogen molecular sieve, an alumina precursor, and an acid solution, extruding and calcining the mixture to obtain a carrier precursor;

[0017] (2) placing the support precursor into a first impregnation solution containing a cationic Pt salt for a first impregnation to obtain a catalyst precursor I;

[0018] (3) placing the catalyst precursor I into a second impregnation solution containing an alkaline earth metal salt for a second impregnation to obtain a catalyst precursor II;

[0019] (4) calcining the catalyst precursor II to obtain a hydroisomerization catalyst.

[0020] 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 precious metal active component Pt, 0.5-5 wt% of an alkaline earth metal active component and 94.2-99.4 wt% of a carrier; wherein the precious metal active component Pt is dispersed on the carrier in a single-atom state.

[0021] The third aspect of the present invention provides a use 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 oil base oil.

[0022] Through the above technical solution, the beneficial technical effects achieved by the present invention are as follows:

[0023] 1) The preparation method of the hydroisomerization catalyst provided in the present invention uses an acidic hydrogen-type molecular sieve and alumina to prepare a support precursor. A cationic Pt salt is first impregnated on the support precursor, and then an alkaline earth metal salt is impregnated. The alkaline earth metal salt can fill and block the vacancies between the Pt atoms dispersed on the support in a single atomic state, thereby preventing the agglomeration of the single-atomized noble metal Pt during the activation process of calcination to form the catalyst, so that the noble metal Pt in the catalyst remains dispersed in an atomic state. On the other hand, it does not cause a large loss of acidic active sites near the noble metal Pt in the support, which is beneficial to improving the activity of the catalyst and maintaining good hydroisomerization selectivity.

[0024] 2) The hydroisomerization catalyst provided by the present invention has high hydroisomerization activity and good selectivity for isomerized products. It can reduce the cloud point and pour point of lubricating oil base oil, significantly improve the low-temperature fluidity of lubricating oil base oil, and significantly increase the yield of lubricating oil base oil.

[0025] 3) When preparing lubricating base oil, the hydroisomerization catalyst provided in the present invention can reduce the cloud point of the lubricating base oil while increasing the yield of the lubricating base oil, reducing the production ratio of non-selective target products such as gas and naphtha, and reducing production energy consumption, thereby significantly improving economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG1 is a spherical aberration electron microscope image of catalyst 1 prepared in Example 1;

[0027] Figure 2 is a spherical aberration electron microscope image of catalyst D1 prepared in Comparative Example 1;

[0028] Figure 3 is a spherical aberration electron microscope image of catalyst D2 prepared in Comparative Example 2;

[0029] FIG4 is a spherical aberration electron microscope image of catalyst D3 prepared in Comparative Example 3;

[0030] FIG5 is an H2-TPR characterization diagram of the hydroisomerization catalysts prepared in Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0031] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0032] A first aspect of the present invention provides a method for preparing a hydroisomerization catalyst, wherein the method comprises the following steps:

[0033] (1) mixing a hydrogen molecular sieve, an alumina precursor, and an acid solution, extruding and calcining the mixture to obtain a carrier precursor;

[0034] (2) placing the support precursor into a first impregnation solution containing a cationic Pt salt for a first impregnation to obtain a catalyst precursor I;

[0035] (3) placing the catalyst precursor I into a second impregnation solution containing an alkaline earth metal salt for a second impregnation to obtain a catalyst precursor II;

[0036] (4) calcining the catalyst precursor II to obtain a hydroisomerization catalyst.

[0037] Among them, in the present invention, the inventors discovered through research that a carrier precursor is prepared by using an acidic hydrogen-type molecular sieve and an alumina precursor, and a cationic Pt salt is first 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 the Pt dispersed in a single-atom state on the carrier, and can prevent the single-atomized precious metal Pt from agglomerating during the activation process of calcining to form a catalyst, so that the precious metal Pt in the catalyst can still be dispersed in an atomic state. On the other hand, it will not cause a large loss of acidic active sites near the precious metal Pt in the carrier, which is beneficial to improving the activity of the catalyst and maintaining good hydrogenation isomerization selectivity.

[0038] In step (1):

[0039] In one embodiment of the present invention, the content of metal cations in the hydrogen molecular sieve is ≤100ppm, preferably ≤50ppm. The metal cations in the molecular sieve include but are not limited to Na + and / or K + .

[0040] In one embodiment of the present invention, the silicon-aluminum ratio of the hydrogen-type molecular sieve is 50-100, preferably 70-80.

[0041] In one embodiment of the present invention, the hydrogen-type molecular sieve is selected from hydrogen-type MTT molecular sieve and / or hydrogen-type TON molecular sieve, preferably selected from one or more of hydrogen-type ZSM-22, hydrogen-type ZSM-23, hydrogen-type SSZ-32, and hydrogen-type Theta-1, preferably hydrogen-type ZSM-22 and / or hydrogen-type ZSM-23.

[0042] In one embodiment of the present invention, the preparation method of the hydrogen-type molecular sieve comprises: treating the molecular sieve at 450-650°C for 1-5h and then exchanging it with an inorganic ammonium salt to obtain a hydrogen-type molecular sieve; wherein the molecular sieve is selected from MTT molecular sieve and / or TON molecular sieve, and is further selected from one or more of ZSM-22, ZSM-23, SSZ-32, and Theta-1; and the inorganic ammonium salt is selected from one or more of ammonium nitrate, ammonium sulfate, and ammonium chloride.

[0043] Wherein, in the present invention, hydrogen type molecular sieve, with acidity, can be a commercially available product, or can be prepared according to the method for ion exchange of MTT molecular sieve and / or TON molecular sieve using commonly used inorganic ammonium salts such as ammonium nitrate, ammonium sulfate, ammonium chloride, etc. as known in the art. MTT molecular sieve and TON molecular sieve can be commercially available products, or can be prepared according to methods known in the art. For example, MTT molecular sieve can be synthesized with reference to "A method for synthesizing MTT zeolite molecular sieve with short axis morphology" disclosed in CN110683558B. TON molecular sieve can be synthesized with reference to CN106853972B "A stable synthesis method for TON zeolite".

[0044] In one embodiment of the present invention, the alumina precursor is selected from one or more of pseudo-boehmite, activated alumina, and aluminum sol, preferably pseudo-boehmite.

[0045] In one embodiment of the present invention, the acid solution is dilute nitric acid, wherein the concentration of the dilute nitric acid may be 1-10 wt%, preferably 3-5 wt%.

[0046] In the present invention, the amount of acid solution is not particularly limited, and can be added according to conventional addition amounts in the art. For example, based on 90g of hydrogen molecular sieve, the amount of dilute nitric acid added can be 45-65g.

[0047] In one embodiment of the present invention, the feeding amounts of the hydrogen-type molecular sieve and the alumina precursor are such that the prepared catalyst comprises 50-80wt%, preferably 60-75wt% of the molecular sieve and 20-50wt%, preferably 25-40wt% of the alumina, based on the mass of the carrier.

[0048] In the present invention, the content of molecular sieve and alumina in the carrier can be calculated based on the feed amount during the preparation process. The hydrogen-type molecular sieve added during the preparation process is recorded as molecular sieve after the catalyst is prepared, and the mass of the molecular sieve in the catalyst is equal to the feed amount of the hydrogen-type molecular sieve.

[0049] In one embodiment of the present invention, the calcination operating conditions include: a calcination temperature of 250-450° C., preferably 300-400° C.; and a calcination time of 2-10 h, preferably 3-6 h.

[0050] In step (2):

[0051] In one embodiment of the present invention, the cationic Pt salt is selected from one or more of tetraammineplatinum acetate, tetraammineplatinum nitrate, tetraammineplatinum nitrite, tetraammineplatinum sulfate, and tetraammineplatinum chloride, preferably tetraammineplatinum nitrate.

[0052] In one embodiment of the present invention, the amount of the cationic Pt salt added is such that the prepared catalyst contains 0.3-0.8 wt%, preferably 0.35-0.45 wt%, of the precious metal active component Pt based on the mass of the catalyst.

[0053] In one embodiment of the present invention, the feed 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.

[0054] In one embodiment of the present invention, the first impregnation is equal volume impregnation, which is carried out under vacuum, and the impregnation temperature is 20-100°C, preferably 60-80°C.

[0055] In one embodiment of the present invention, the first impregnation is followed by drying to obtain a catalyst precursor I. In the present invention, the drying temperature may be 100-150°C.

[0056] In step (3):

[0057] 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, preferably calcium nitrate and / or magnesium nitrate.

[0058] In one embodiment of the present invention, the alkaline earth metal salt is added in an amount such that the prepared catalyst contains 0.5-5 wt%, preferably 2-4 wt% of alkaline earth metal active components based on the mass of the catalyst.

[0059] In one embodiment of the present invention, the second impregnation is an equal volume impregnation performed under vacuum at a temperature of 20-100°C, preferably 60-80°C.

[0060] In one embodiment of the present invention, drying is performed after the second impregnation to obtain catalyst precursor II.

[0061] In step (4):

[0062] In one embodiment of the present invention, the calcination operating conditions include: a calcination temperature of 250-450° C., preferably 300-400° C.; and a calcination time of 2-10 h, preferably 3-6 h.

[0063] In the present invention, if the calcination temperature is too high, it will easily cause the Pt metal to agglomerate; if the calcination temperature is too low, the metal salt will not be effectively decomposed, making it difficult to form effective active materials during subsequent processing. When the calcination temperature is within the above-defined range, the active component Pt can be dispersed in a single atomic state on the support, resulting in better catalyst activity.

[0064] 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 precious metal active component Pt, 0.5-5 wt% of an alkaline earth metal active component and 94.2-99.4 wt% of a carrier; wherein the precious metal active component Pt is dispersed on the carrier in a single-atom state.

[0065] In the present invention, the contents of the noble metal active component and the alkaline earth metal active component are calculated based on the oxides corresponding to the metals, and the contents of the noble metal active component, the alkaline earth metal active component and the carrier in the hydroisomerization catalyst are calculated based on the feed amount.

[0066] In one embodiment of the present invention, the content of the precious metal active component Pt can be 0.3wt%, 0.35wt%, 0.4wt%, 0.45wt%, 0.5wt%, 0.55wt%, 0.6wt%, 0.65wt%, 0.7wt%, 0.75wt%, 0.8wt%, and any value among these values, preferably 0.35-0.45wt%.

[0067] In one embodiment of the present invention, the content of the alkaline earth metal active component can be 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, and any value among these values, preferably 2-4wt%.

[0068] In one embodiment of the present invention, the content of the carrier can be 94.2wt%, 94.6wt%, 95wt%, 95.3wt%, 95.5wt%, 95.8wt%, 96wt%, 96.3wt%, 96.5wt%, 96.8wt%, 97wt%, 97.3wt%, 97.5wt%, 97.7wt%, 98wt%, 98.3wt%, 98.5wt%, 99wt%, 99.4wt%, and any value among these values, preferably 95-98wt%.

[0069] In one embodiment of the present invention, the alkaline earth metal active component is Mg and / or Ca. 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.

[0070] In one embodiment of the present invention, the support comprises 50-80 wt%, preferably 60-75 wt% of molecular sieve and 20-50 wt%, preferably 25-40 wt% of alumina, based on the mass of the support.

[0071] In one embodiment of the present invention, the silicon to aluminum ratio of the molecular sieve is 50-100, preferably 70-80.

[0072] In one embodiment of the present invention, the molecular sieve is selected from MTT molecular sieve and / or TON molecular sieve, preferably one or more selected from ZSM-22, ZSM-23, SSZ-32, Theta-1.

[0073] The third aspect of the present invention provides a use 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 oil base oil.

[0074] Among them, the hydroisomerization catalyst provided by the present invention has the precious metal active component Pt dispersed in a single-atom state on the carrier, which can effectively improve the dispersion of the precious metal in the hydroisomerization catalyst and the activity of the hydroisomerization catalyst, effectively improve the low-temperature fluidity of the isomerization product, and improve the cloud point and pour point of the lubricating oil base oil while increasing the yield of the lubricating oil base oil.

[0075] The present invention will be described in detail below through examples.

[0076] Example 1

[0077] (1) Referring to the method described in Example 2 of CN110683558B, a ZSM-23 molecular sieve with a silicon-aluminum ratio of 70 was prepared; the ZSM-23 molecular sieve was calcined at 550°C for 3 hours and then exchanged with ammonium nitrate twice to obtain an acidic hydrogen-type ZSM-23 molecular sieve; wherein Na + Content <100ppm;

[0078] 90 g of the hydrogenated ZSM-23 molecular sieve, 40 g of SB powder (with an Al2O3 content of 75 wt%), and 57 g of a 4.5% dilute nitric acid solution were mixed, rolled, extruded, dried at 120° C., and calcined at 350° C. for 6 h to obtain a carrier precursor.

[0079] (2) Under vacuum conditions, using an aqueous solution of tetraammineplatinum nitrate as a first impregnation solution, placing the above-mentioned support precursor in the first impregnation solution, performing a first equal volume impregnation at 70° C., and drying at 120° C. to obtain catalyst precursor I;

[0080] (3) Under vacuum conditions, using an aqueous solution of magnesium nitrate as a second impregnation solution, placing the catalyst precursor I into the second impregnation solution, performing a second equal volume impregnation at 70° C., and drying at 120° C. to obtain a catalyst precursor II;

[0081] (4) The catalyst precursor II was calcined at 350° C. for 6 h to obtain a hydroisomerization catalyst 1.

[0082] Calculated based on the feed amount, the hydroisomerization catalyst 1 includes 0.45 wt% of the precious metal active component Pt, 2.2 wt% of the alkaline earth metal active component Mg and 97.35 wt% of the carrier; wherein the carrier contains 75 wt% of the ZSM-23 molecular sieve and 25 wt% of alumina.

[0083] Example 2

[0084] (1) Referring to the method described in Example 2 of CN110683558B, a ZSM-23 molecular sieve with a silicon-aluminum ratio of 70 was prepared; the ZSM-23 molecular sieve was treated at 550°C for 3 hours and then exchanged with ammonium nitrate twice to obtain an acidic hydrogen-type ZSM-23 molecular sieve; wherein Na + Content <100ppm;

[0085] 90 g of the hydrogenated ZSM-23 molecular sieve, 80 g of SB powder (with an Al2O3 content of 75 wt%), and 50 g of a 4% by mass dilute nitric acid solution were mixed, rolled, extruded, dried at 120° C., and calcined at 400° C. for 6 h to obtain a carrier precursor.

[0086] (2) Under vacuum conditions, using an aqueous solution of tetraammineplatinum nitrate as a first impregnation solution, placing the above-mentioned support precursor in the first impregnation solution, performing a first equal volume impregnation at 70° C., and drying at 120° C. to obtain catalyst precursor I;

[0087] (3) Under vacuum conditions, using an aqueous solution of magnesium nitrate as a second impregnation solution, placing the catalyst precursor I into the second impregnation solution, performing a second equal volume impregnation at 70° C., and drying at 120° C. to obtain a catalyst precursor II;

[0088] (4) The catalyst precursor II was calcined at 400°C for 6 hours to obtain the hydroisomerization catalyst 2.

[0089] According to the feed amount, the hydroisomerization catalyst 2 includes 0.4 wt% of the precious metal active component Pt, 3.0 wt% of the alkaline earth metal active component Mg and 96.6 wt% of the carrier; wherein the carrier contains 60 wt% of the ZSM-23 molecular sieve and 40 wt% of alumina.

[0090] Example 3

[0091] (1) Referring to the method described in Example 2 of CN110683558B, a ZSM-23 molecular sieve with a silicon-aluminum ratio of 70 was prepared; the ZSM-23 molecular sieve was treated at 550°C for 3 hours and then exchanged with ammonium nitrate twice to obtain an acidic hydrogen-type ZSM-23 molecular sieve; wherein Na + Content <100ppm;

[0092] 90 g of the hydrogenated ZSM-23 molecular sieve, 80 g of SB powder (with an Al2O3 content of 75 wt%), and 50 g of a 4% by mass dilute nitric acid solution were mixed, rolled, extruded, dried at 120° C., and calcined at 300° C. for 4 h to obtain a carrier precursor.

[0093] (2) Under vacuum conditions, using an aqueous solution of tetraammineplatinum nitrate as a first impregnation solution, placing the above-mentioned support precursor in the first impregnation solution, performing a first equal volume impregnation at 60° C., and drying at 120° C. to obtain catalyst precursor I;

[0094] (3) Under vacuum conditions, using an aqueous solution of magnesium nitrate as a second impregnation solution, placing the catalyst precursor I into the second impregnation solution, performing a second equal volume impregnation at 60° C., and drying at 120° C. to obtain a catalyst precursor II;

[0095] (4) The catalyst precursor II was calcined at 300°C for 4 hours to obtain the hydroisomerization catalyst 3.

[0096] According to the feed amount, the hydroisomerization catalyst 3 includes 0.35 wt% of the precious metal active component Pt, 4.0 wt% of the alkaline earth metal active component Mg and 95.65 wt% of the carrier; wherein the carrier contains 60 wt% of the ZSM-23 molecular sieve and 40 wt% of the alumina.

[0097] Example 4

[0098] (1) Referring to the method described in Example 2 of CN106853972B, a ZSM-22 molecular sieve with a silicon-aluminum ratio of 80 was prepared; the ZSM-22 molecular sieve was treated at 550°C for 3 hours and then exchanged with ammonium nitrate twice to obtain an acidic hydrogen-type ZSM-22 molecular sieve; wherein, K + Content <100ppm;

[0099] 90 g of the hydrogenated ZSM-22 molecular sieve, 80 g of SB powder (with an Al2O3 content of 75 wt%), and 57 g of a 4.5% dilute nitric acid solution were mixed, rolled, extruded, dried at 120° C., and calcined at 300° C. for 6 h to obtain a carrier precursor.

[0100] (2) Under vacuum conditions, using an aqueous solution of tetraammineplatinum nitrate as a first impregnation solution, placing the above-mentioned support precursor into the first impregnation solution, performing a first equal volume impregnation at 80° C., and drying at 120° C. to obtain catalyst precursor I;

[0101] (3) Under vacuum conditions, using an aqueous solution of calcium nitrate as a second impregnation solution, placing the catalyst precursor I into the second impregnation solution, performing a second equal volume impregnation at 80° C., and drying at 120° C. to obtain a catalyst precursor II;

[0102] (4) The catalyst precursor II was calcined at 300° C. for 6 h to obtain the hydroisomerization catalyst 4.

[0103] According to the feed amount, the hydroisomerization catalyst 4 includes 0.35 wt% of the precious metal active component Pt, 4.0 wt% of the alkaline earth metal active component Ca and 95.65 wt% of the carrier; wherein the carrier contains 60 wt% of the ZSM-22 molecular sieve and 40 wt% of the alumina.

[0104] Comparative Example 1:

[0105] The same as Example 1, except that magnesium nitrate is impregnated first and then tetraammine platinum nitrate is impregnated, specifically as follows:

[0106] (1) Referring to the method described in Example 2 of CN110683558B, a ZSM-23 molecular sieve with a silicon-aluminum ratio of 70 was prepared; the ZSM-23 molecular sieve was treated at 550°C for 3 hours and then exchanged with ammonium nitrate twice to obtain an acidic hydrogen-type ZSM-23 molecular sieve; wherein Na + Content <100ppm;

[0107] 90 g of the hydrogenated ZSM-23 molecular sieve, 40 g of SB powder (with an Al2O3 content of 75 wt%), and 57 g of a 4.5% dilute nitric acid solution were mixed, rolled, extruded, dried at 120° C., and calcined at 350° C. for 6 h to obtain a carrier precursor.

[0108] (2) Under vacuum conditions, using an aqueous solution of magnesium nitrate as a first impregnation liquid, placing the above-mentioned support precursor into the first impregnation liquid, performing a first equal volume impregnation at 70° C., and drying at 120° C. to obtain catalyst precursor I;

[0109] (3) Under vacuum conditions, using an aqueous solution of tetraammineplatinum nitrate as a second impregnation solution, placing the catalyst precursor I into the second impregnation solution, performing a second equal volume impregnation at 70° C., and drying at 120° C. to obtain a catalyst precursor II;

[0110] (4) The catalyst precursor II was calcined at 350°C for 6 hours to obtain the hydroisomerization catalyst D1.

[0111] Calculated based on the feed amount, the hydroisomerization catalyst D1 includes 0.45 wt% of the precious metal active component Pt, 2.2 wt% of the alkaline earth metal active component Mg and 97.35 wt% of the carrier; wherein the carrier contains 75 wt% of the ZSM-23 molecular sieve and 25 wt% of alumina.

[0112] Comparative Example 2:

[0113] The same as Example 1, except that tetraammine platinum nitrate and magnesium nitrate are impregnated together, specifically as follows:

[0114] (1) Referring to the method described in Example 2 of CN110683558B, a ZSM-23 molecular sieve with a silicon-aluminum ratio of 70 was prepared; the ZSM-23 molecular sieve was treated at 550°C for 3 hours and then exchanged with ammonium nitrate twice to obtain an acidic hydrogen-type ZSM-23 molecular sieve; wherein Na + Content <100ppm;

[0115] 90 g of the hydrogenated ZSM-23 molecular sieve, 40 g of SB powder (with an Al2O3 content of 75 wt%), and 57 g of a 4.5% dilute nitric acid solution were mixed, rolled, extruded, dried at 120° C., and calcined at 350° C. for 6 h to obtain a carrier precursor.

[0116] (2) Under vacuum conditions, using an aqueous solution of tetraammine platinum nitrate and magnesium nitrate as an impregnation solution, placing the support precursor into the impregnation solution, performing equal volume impregnation at 70° C., and drying at 120° C. to obtain a catalyst precursor;

[0117] (3) The catalyst precursor was calcined at 350°C for 6 hours to obtain a hydroisomerization catalyst D2.

[0118] Calculated based on the feed amount, the hydroisomerization catalyst D2 includes 0.45 wt% of the precious metal active component Pt, 2.2 wt% of the alkaline earth metal active component Mg and 97.35 wt% of the carrier; wherein the carrier contains 75 wt% of the ZSM-23 molecular sieve and 25 wt% of alumina.

[0119] Comparative Example 3:

[0120] The same as Example 1, except that the impregnation of magnesium nitrate is omitted, specifically as follows:

[0121] (1) Referring to the method described in Example 2 of CN110683558B, a ZSM-23 molecular sieve with a silicon-aluminum ratio of 70 was prepared; the ZSM-23 molecular sieve was treated at 550°C for 3 hours and then exchanged with ammonium nitrate twice to obtain an acidic hydrogen-type ZSM-23 molecular sieve; wherein Na + Content <100ppm;

[0122] 90 g of the hydrogenated ZSM-23 molecular sieve, 40 g of SB powder (with an Al2O3 content of 75 wt%), and 57 g of a 4.5% dilute nitric acid solution were mixed, rolled, extruded, dried at 120° C., and calcined at 350° C. for 6 h to obtain a carrier precursor.

[0123] (2) Under vacuum conditions, using an aqueous solution of tetraammineplatinum nitrate as a first impregnation solution, placing the above-mentioned support precursor in the first impregnation solution, performing a first equal volume impregnation at 70° C., and drying at 120° C. to obtain catalyst precursor I;

[0124] (4) The catalyst precursor I was calcined at 350°C for 6 h to obtain a hydroisomerization catalyst D3.

[0125] Calculated based on the feed amount, the hydroisomerization catalyst D3 includes 0.45 wt% of the precious metal active component Pt and 99.55 wt% of the carrier; wherein the carrier contains 75 wt% of the ZSM-23 molecular sieve and 25 wt% of alumina.

[0126] Test Example 1

[0127] The hydroisomerization catalysts prepared in Example 1 and Comparative Examples 1-3 were characterized using spherical aberration electron microscopy, with the results shown in Figures 1-4. Figure 1 is a spherical aberration electron microscopy image of Catalyst 1 prepared in Example 1. As shown in Figure 1, the platinum metal (bright spot in the image) in Catalyst 1 is essentially distributed in a single atomic state.

[0128] Figure 2 is an electron micrograph of catalyst D1 prepared in Comparative Example 1 with spherical aberration. As shown in Figure 2, catalyst D1 contains a large number of 2-4 nm platinum metal clusters. Figure 3 is an electron micrograph of catalyst D2 prepared in Comparative Example 2 with spherical aberration. As shown in Figure 3, catalyst D2 contains a certain amount of 2-4 nm platinum metal clusters. Figure 4 is an electron micrograph of catalyst D3 prepared in Comparative Example 3 with spherical aberration. As shown in Figure 4, the Pt metal in catalyst D3 is essentially entirely 2-4 nm platinum metal clusters, with essentially no single atomically dispersed Pt metal present.

[0129] Test Example 2

[0130] The hydroisomerization catalysts prepared in Example 1 and Comparative Example 1 were characterized by H2-TPR, and the results are shown in Figure 5. As shown in Figure 5, the reduction peak of Hydroisomerization Catalyst 1, which has a single-atom dispersion state, appears at a temperature approximately 20°C higher than that of Hydroisomerization Catalyst D1. This indicates that the Pt atoms in Hydroisomerization Catalyst 1 are more difficult to reduce and have a stronger interaction with the support, further demonstrating that the Pt in Hydroisomerization Catalyst 1 has better stability and dispersion.

[0131] Test Example 3

[0132] The catalytic activity of the hydroisomerization catalysts prepared in Examples 1-4 and Comparative Examples 1-3 was evaluated using the high-wax hydrorefining product from the Daqing No. 4 production line as feedstock in an isothermal fixed-bed reactor. The reaction temperature was adjusted to achieve similar cloud points for the lubricating base oils. The feedstock properties are shown in Table 1, and the evaluation conditions and results are shown in Table 2.

[0133] Table 1

[0134] Table 2

[0135] As shown in Table 2, the catalysts prepared in Examples 1-4 of the present invention have excellent hydroisomerization pour point depressing ability, and can significantly increase the C5+ liquid yield and the yield of the lubricant base oil while lowering the cloud point of the lubricant base oil. They can also significantly lower the pour point of the lubricant base oil, increase the kinematic viscosity of the lubricant base oil, and significantly improve the low-temperature fluidity of the lubricant base oil.

[0136] The test results of Comparative Example 1 show that Catalyst D1, prepared in Comparative Example 1 by first impregnating Pt and then Mg, can produce a lubricating base oil with a low cloud point only when reacted at 390°C. However, compared with Example 1, the yield of C5+ liquids and lubricating base oil in Comparative Example 1 is significantly reduced, and the kinematic viscosity of the lubricating base oil is also relatively low.

[0137] The test results of Comparative Example 2 show that Catalyst D2, prepared by the combined impregnation of Pt and Mg in Comparative Example 2, can only produce a lubricating base oil with a low cloud point when reacted at 383°C. However, compared with Example 1, Comparative Example 2 exhibits significantly lower C5+ liquid yields and lubricating base oil yields, resulting in significant losses of the heavy base oil fraction in the feedstock, and poor economic performance.

[0138] The test results of Comparative Example 3 show that while Catalyst D3, prepared in Comparative Example 3 by omitting Mg, can produce a lubricating base oil with a cloud point of -4°C, the yield of C5+ liquids and lubricating base oil in Comparative Example 3 is significantly reduced compared to Example 1, resulting in significant losses of heavy base oil fractions in the feedstock, and poor economic benefits. Furthermore, the lubricating base oil in Comparative Example 3 has a high pour point and viscosity index, low kinematic viscosity, and poor low-temperature fluidity.

[0139] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing a hydroisomerization catalyst, characterized in that: The method comprises the following steps: (1) mixing a hydrogen molecular sieve, an alumina precursor and an acid solution, extruding and calcining the mixture to obtain a carrier precursor; (2) placing the support precursor into a first impregnation solution containing a cationic Pt salt for a first impregnation to obtain a catalyst precursor I; (3) placing the catalyst precursor I into a second impregnation solution containing an alkaline earth metal salt for a second impregnation to obtain a catalyst precursor II; (4) calcining 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 molecular sieve is ≤100ppm; wherein the metal cations include Na + and / or K + ; And / or, the silicon-aluminum ratio of the hydrogen-type molecular sieve is 50-100; And / or, the hydrogen-type molecular sieve is selected from hydrogen-type MTT molecular sieve and / or 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 hydrogen-type ZSM-22, hydrogen-type ZSM-23, hydrogen-type SSZ-32, and hydrogen-type Theta-1.

4. The preparation method according to claim 1, wherein The alumina precursor is selected from one or more of pseudo-boehmite, activated alumina, and aluminum sol; And / or, the feeding amounts of the hydrogen-type molecular sieve and the alumina precursor are such that the prepared catalyst comprises 50-80 wt% of the molecular sieve and 20-50 wt% of the alumina based on the mass of the carrier.

5. The preparation method according to claim 4, wherein The feed amounts of the hydrogen-type molecular sieve and the alumina precursor are such that the prepared catalyst comprises 60-75 wt% of the molecular sieve and 25-40 wt% of the alumina based on the mass of the carrier.

6. The preparation method according to claim 1, wherein The operating conditions of the calcination include: a calcination temperature of 250-450° C. and a calcination time of 2-10 hours.

7. The preparation method according to claim 6, wherein: The calcination operating conditions include: calcination temperature of 300-400° C., calcination time of 3-6 hours.

8. The preparation method according to claim 1, wherein The cationic Pt salt is selected from one or more of tetraammineplatinum acetate, tetraammineplatinum nitrate, tetraammineplatinum nitrite, tetraammineplatinum sulfate, and tetraammineplatinum chloride; and / or, the amount of the cationic Pt salt added is such that the prepared catalyst contains 0.3-0.8 wt % of the precious metal active component Pt based on the mass of the catalyst; and / or, the feed amount of the carrier precursor is such that the prepared catalyst contains 94.2-99.4 wt % of the carrier based on the mass of the catalyst; And / or, the first impregnation is an equal volume impregnation performed under vacuum at an impregnation temperature of 20-100°C.

9. The preparation method according to claim 8, wherein: The amount of the cationic Pt salt added is such that the prepared catalyst contains 0.35-0.45 wt % of the precious metal active component Pt based on the mass of the catalyst; And / or, the feed amount of the carrier precursor is such that the prepared catalyst contains 95-98 wt % of the carrier based on the mass of the catalyst.

10. 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 alkaline earth metal salt is fed in such an amount that the prepared catalyst contains 0.5-5 wt % of alkaline earth metal active components based on the mass of the catalyst; And / or, the second impregnation is an equal volume impregnation performed under vacuum at a temperature of 20-100°C.

11. The preparation method according to claim 10, wherein: The amount of the alkaline earth metal salt added is such that the prepared catalyst contains 2-4 wt% of alkaline earth metal active components based on the mass of the catalyst.

12. The preparation method according to claim 1, wherein: The calcination operating conditions include: calcination temperature of 250-450° C., and calcination time of 2-10 hours.

13. The preparation method according to claim 12, wherein: The calcination operating conditions include: calcination temperature of 300-400° C., and calcination time of 3-6 hours.

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

15. The catalyst according to claim 14, 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 % of the molecular sieve and 20-50 wt % of alumina.

16. The catalyst according to claim 15, wherein Based on the mass of the carrier, the carrier comprises 60-75 wt% of molecular sieve and 25-40 wt% of alumina.

17. The catalyst according to claim 14, wherein The molecular sieve is selected from MTT molecular sieve and / or TON molecular sieve.

18. The catalyst according to claim 17, wherein The molecular sieve is selected from one or more of ZSM-22, ZSM-23, SSZ-32, and Theta-1.

19. Use of the catalyst prepared by the method according to any one of claims 1 to 0 or the catalyst according to claims 11 to 18 in the production of lubricating oil base oil.

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