Hydroisomerization catalysts, processes for their preparation and use

Abstract

The application relates to the field of catalysts, and discloses a hydroisomerization catalyst and a preparation method and application thereof, the catalyst comprising a carrier and an active metal component supported on the carrier, the carrier comprising ZSM-48 molecular sieve, the molar ratio of silicon oxide and aluminum oxide in the ZSM-48 molecular sieve being not less than 40, the specific surface area of the ZSM-48 molecular sieve being not less than 200 m 2 / g, the crystal grain of the ZSM-48 molecular sieve being ellipsoidal, the length-diameter ratio being not more than 700 nm and the length-short diameter ratio being 1-3:1, the active metal component being Pt and / or Pd, and the content of alkali metal oxide in the carrier being not higher than 0.001 wt% based on the total amount of the carrier. Based on the ZSM-48 molecular sieve with the specific structure, the catalyst is prepared by the mode of shaping first and then ammonium exchange, the post-processing difficulty is low, the content of alkali metal in the catalyst is extremely low, and the obtained hydroisomerization catalyst has higher catalytic activity in a hydroisomerization reaction of hydrocarbon oil.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalysts, in particular to a hydroisomerization catalyst and a preparation method and application thereof. BACKGROUND

[0002] Hydroisomerization reaction of hydrocarbon oil is to isomerize paraffin in the presence of hydroisomerization catalyst, which improves the low-temperature fluidity of oil products while maintaining appropriate viscosity through the above method. The support material of hydroisomerization catalyst usually contains different types of molecular sieves, and the molecular sieve material has high acidity and high specific surface area, which is an excellent acidic catalyst. At the same time, the molecular sieve material has strong chemical stability and hydrothermal stability, and is difficult to be corroded and dissolved by reactants to be destroyed. Compared with the commonly used homogeneous catalyst, the molecular sieve material catalyst can be directly reused without separation, and will not pollute the environment and products. Many attempts have been made in the prior art to improve the catalytic effect of the catalyst by modifying the molecular sieve. However, the pour point of the product obtained by hydroisomerization of hydrocarbon oil raw material needs to be further reduced to meet the industrial demand.

[0003] ZSM-48 type molecular sieve is a new type of high-silicon molecular sieve developed in the 1980s, which has a two-dimensional ten-membered ring pore structure, belongs to the orthorhombic system, and the pores are connected by 5-membered rings, and the pore opening diameter is about 0.6 nm. Its characteristics are high silicon-aluminum molar ratio and tubular linear channel, which can accommodate organic molecules with smaller kinetic radius than benzene. In theory, ZSM-48 type molecular sieve has a small "self-blocking effect" of the pore, and the pore size is suitable for shape-selective isomerization of paraffin. The existing technology mainly focuses on the control of ZSM-48 molecular sieve crystal phase and the selection of template used in the synthesis process, and there are few reports on the control of ZSM-48 molecular sieve morphology and size. At the same time, the preparation process of the catalyst containing ZSM-48 molecular sieve in the prior art is long, which needs to be dried and calcined for many times, and the production efficiency needs to be further improved.

[0004] In addition, the preparation of catalysts in the prior art usually first carries out ammonium exchange after crystallization, and then carries out the method of extruding into strips, but the alkali metal content in the obtained catalyst is generally below 0.1 wt%, it is difficult to further reduce, and the process flow is complex, which needs to go through multiple drying and calcination. For example, CN110756220A discloses a preparation method of ZSM-35 / ZSM-5 co-crystal molecular sieve catalyst, which adopts a preparation method of crystallization, filtration, washing, ammonium exchange, drying and calcination to obtain a molecular sieve product, and then extrudes into strips with a binder, an acid and an additive. The preparation flow is complex, the post-treatment is difficult, multiple drying and calcination processes are needed, which is not conducive to industrial production. And the filtration efficiency of ammonium exchange is low, which is not conducive to reducing the alkali metal content in the molecular sieve. This also limits the catalytic activity of the catalyst. Therefore, how to further improve the catalytic activity of the catalyst is also an important problem existing in the prior art. SUMMARY

[0005] The purpose of the present application is to overcome the problems of long preparation flow, high alkali metal content and limited catalyst activity of the hydrogen isomerization catalyst in the prior art, and to provide a hydrogen isomerization catalyst, a preparation method and application thereof. The alkali metal content of the catalyst is extremely low, and the catalyst activity is high.

[0006] In order to achieve the above-mentioned purpose, the first aspect of the present application provides a hydrogen isomerization catalyst, which comprises a carrier and an active metal component loaded on the carrier, the carrier comprises ZSM-48 molecular sieve, the molar ratio of silicon oxide to aluminum oxide in the ZSM-48 molecular sieve is not less than 40, the specific surface area of the ZSM-48 molecular sieve is not less than 200 m 2 / g, the crystal grains of the ZSM-48 molecular sieve are ellipsoidal, the length diameter is not more than 700 nm, and the length to short diameter ratio is 1-3:1.

[0007] The active metal component is Pt and / or Pd.

[0008] Among them, the content of alkali metal oxide in the carrier is not more than 0.001 wt% based on the total amount of the carrier.

[0009] The second aspect of the present application provides a preparation method of a hydrogen isomerization catalyst, which comprises the following steps:

[0010] Step one: molding the dry powder of ZSM-48 molecular sieve to obtain a molded carrier;

[0011] The molar ratio of silicon oxide to aluminum oxide in the ZSM-48 molecular sieve is not less than 40, the specific surface area of the ZSM-48 molecular sieve is not less than 200 m 2 / g, the crystal grains of the ZSM-48 molecular sieve are ellipsoidal, the length diameter is not more than 700 nm, and the length to short diameter ratio is 1-3:1.

[0012] Based on the mass of the dried ZSM-48 molecular sieve powder, the moisture content of the dried ZSM-48 molecular sieve powder is less than 15 wt%.

[0013] Step 2: Perform ammonium exchange on the molded carrier;

[0014] Step 3: Introduce an active metal component onto the product obtained in Step 2 to obtain a hydroisomerization catalyst;

[0015] The active metal component is Pt and / or Pd.

[0016] A third aspect of the present invention provides a hydroisomerization catalyst prepared by the above-described preparation method.

[0017] The fourth aspect of the present invention provides the application of the hydroisomerization catalyst described in the first or third aspect above in the hydroisomerization reaction of hydrocarbon oils.

[0018] The method for preparing the hydroisomerization catalyst provided by this invention has a short preparation process and is simple to operate. Based on the ZSM-48 molecular sieve with a specific structure, the method of pre-forming followed by ammonium exchange has low post-processing difficulty. At the same time, the alkali metal content in the catalyst is extremely low, and the obtained hydroisomerization catalyst has higher catalytic activity in the hydroisomerization reaction of hydrocarbon oils. Attached Figure Description

[0019] Figure 1 The X-ray diffraction pattern of seed crystal A1 obtained in Preparation Example 1-1 after calcination;

[0020] Figure 2 The X-ray diffraction pattern of seed crystal A3 obtained in Preparation Examples 1-3 after calcination;

[0021] Figure 3 This is a SEM image of the ZSM-48 molecular sieve obtained in Preparation Example 2-1. Detailed Implementation

[0022] The endpoints and any values ​​of the ranges 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 endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0023] The first aspect of this invention provides a hydroisomerization catalyst, comprising a support and an active metal component supported on the support, wherein the support contains a ZSM-48 molecular sieve, the molar ratio of silica to alumina in the ZSM-48 molecular sieve is not less than 40, and the specific surface area of ​​the ZSM-48 molecular sieve is not less than 200 m². 2 / g, the ZSM-48 molecular sieve crystals are ellipsoidal, with a major axis not exceeding 700nm and a major axis to minor axis ratio of 1-3:1;

[0024] The active metal component is Pt and / or Pd;

[0025] Based on the total amount of the carrier, the content of alkaline metal oxides in the carrier is not higher than 0.001 wt%.

[0026] According to the present invention, the hydroisomerization catalyst support contains a ZSM-48 molecular sieve with a specific morphology. The ZSM-48 molecular sieve has an ellipsoidal morphology with a small aspect ratio, a high silicon-to-aluminum ratio, and a large specific surface area. The content of alkali metals in the support is extremely low. The resulting hydroisomerization catalyst has higher catalytic activity in the hydroisomerization reaction of hydrocarbon oils.

[0027] In this invention, the content of alkali metal oxides was determined using a Rigaku Electric Industries, Ltd. 3271E X-ray fluorescence spectrometer (XRF) to analyze the composition of the sample. Those skilled in the art will understand that the standard accuracy of XRF testing is 10 ppm; therefore, a test result of 0 indicates that the content of alkali metal oxides is not higher than 0.001 wt%.

[0028] In this invention, preferably, the content of molecular sieve on a dry basis is 20-80% by weight, more preferably 30-70% by weight, based on the mass of the catalyst; preferably, the content of the active metal component on an elemental basis is 0.1-20% by weight, more preferably 0.2-10% by weight, based on the total amount of catalyst.

[0029] In this invention, preferably, the catalyst also contains a binder. There is no particular limitation on the specific type of binder; any conventional choice in the art is acceptable. Preferably, the binder is alumina and / or silicon dioxide.

[0030] Preferably, the binder content is 20-80% by weight, based on the total amount of catalyst.

[0031] According to a preferred embodiment of the present invention, the content of molecular sieve on a dry basis is 30-70% by weight, the content of binder is 20-80% by weight, and the content of active metal component is 0.2-10% by weight, based on the mass of the catalyst.

[0032] In this invention, preferably, the aspect ratio of the ZSM-48 molecular sieve is 1-2:1; preferably, the grain size of the ZSM-48 molecular sieve is 300-700nm, and more preferably 400-600nm.

[0033] According to the present invention, preferably, the specific surface area of ​​the ZSM-48 molecular sieve is 200-280 m². 2 / g; preferably, the pore volume of the ZSM-48 molecular sieve is 0.2-0.3 mL / g. Under the above preferred conditions, the molecular sieve exhibits good diffusion performance of isomer products, thereby improving the catalytic effect of the hydroisomerization catalyst.

[0034] A second aspect of this invention provides a method for preparing a hydroisomerization catalyst, comprising the following steps:

[0035] Step 1: Shape the dried powder of ZSM-48 molecular sieve into a molded carrier;

[0036] The molar ratio of silica to alumina in the ZSM-48 molecular sieve is not less than 40, and the specific surface area of ​​the ZSM-48 molecular sieve is not less than 200 m². 2 / g, the ZSM-48 molecular sieve crystals are ellipsoidal, with a major axis not exceeding 700nm and a major axis to minor axis ratio of 1-3:1;

[0037] Based on the mass of the dried ZSM-48 molecular sieve powder, the moisture content of the dried ZSM-48 molecular sieve powder is less than 15 wt%.

[0038] Step 2: Perform ammonium exchange on the molded carrier;

[0039] Step 3: Introduce an active metal component onto the product obtained in Step 2 to obtain a hydroisomerization catalyst;

[0040] The active metal component is Pt and / or Pd.

[0041] In this invention, the dried ZSM-48 molecular sieve powder refers to dried ZSM-48 molecular sieve powder. Drying is a conventional operation in the art, as long as the dried ZSM-48 molecular sieve powder meets the aforementioned moisture content requirements. In conventional catalyst preparation processes, the dried and calcined molecular sieve powder typically undergoes ammonium exchange in a solution before drying, shaping, and calcining. On the one hand, the alkali metal content in the support after conventional ammonium exchange is generally 0.01-1 wt%, limiting catalytic activity; on the other hand, directly processing the molecular sieve powder after ammonium exchange is difficult. The inventors of this invention have discovered that shaping the dried ZSM-48 molecular sieve powder before ammonium exchange can significantly reduce the alkali metal content in the support and improve the catalytic activity of the catalyst.

[0042] In this invention, the method for testing the moisture content is as follows: Take a mass M of dried ZSM-48 molecular sieve powder and place it in an oven. Dry it at 105-110℃ for about 6-8 hours until the sample weight no longer changes. Weigh the dried sample and record it as M. 烘干后 The moisture content of the dried ZSM-48 molecular sieve powder can be calculated.

[0043] Moisture content (wt%) = (MM) 烘干后 ) / M3100%.

[0044] In this invention, preferably, the preparation method of the ZSM-48 molecular sieve includes the following steps:

[0045] (1) Provide a mixture containing silicon source, alkali source, aluminum source, template agent, water and molecular sieve mother liquor and seed crystals;

[0046] (2) The mixture is subjected to a crystallization reaction; the conditions for the crystallization reaction include: reacting at 20℃-50℃ for 1-20h, reacting at 50℃-80℃ for 1-34h, and then reacting at 80℃-180℃ for 1-70h.

[0047] (3) The mixture obtained from the crystallization reaction in step (2) is subjected to solid-liquid separation to obtain ZSM-48 molecular sieve and molecular sieve mother liquor. The molecular sieve mother liquor is returned to step (1).

[0048] The method further includes, optionally, step (4), which includes: acidifying and depositing the molecular sieve mother liquor, then performing solid-liquid separation, and returning the filtrate to step (1);

[0049] In step (1), the mass percentage of the added seed crystals is not less than 10% of the mass percentage of the silicon source, and the silicon source is SiO2.

[0050] According to the present invention, the ZSM-48 molecular sieve is prepared by reusing the molecular sieve mother liquor and introducing seed crystals, which is beneficial to the formation of small crystals. In this invention, the crystallization process is carried out in three stages at different temperatures, strictly controlling the progress and temperature of the crystallization reaction. Compared with the prior art, setting the crystallization reaction process at a low temperature helps to control the growth of crystals.

[0051] In this invention, those skilled in the art will understand that step (3) or steps (3) and (4) can be arbitrarily selected to obtain the molecular sieve mother liquor. When the method provided by this invention includes step (4), those skilled in the art will understand that the filtrate provides at least a portion of the molecular sieve mother liquor described in step (1). Using the above-preferred preparation method, the reuse of the molecular sieve mother liquor and the introduction of seed crystals are beneficial to the formation of small crystals.

[0052] In this invention, the proportions of each raw material in step (1) can be adjusted according to actual needs. In order to improve the performance of the molecular sieve in the ZSM-48 molecular sieve precursor, and thus further improve the catalytic performance of the catalyst, preferably, the composition of each component in the mixture in step (1) calculated by molar amount satisfies the following relationship:

[0053] R / SiO2 = 0.01-0.4, preferably 0.01-0.08;

[0054] M + / SiO2 = 0.01-0.4, preferably 0.1-0.2;

[0055] Al2O3 / SiO2 = 0-0.02, preferably 0.01-0.015;

[0056] H2O / SiO2 = 5-30, preferably 5-20;

[0057] Wherein, SiO2 refers to SiO2 in the silicon source, R represents the template agent, and M... + Indicates the alkali source.

[0058] According to the present invention, preferably, the conditions for the crystallization reaction in step (2) include: reacting at 20℃-50℃ for 6-20h, reacting at 50℃-80℃ for 12-34h, and then reacting at 80℃-180℃ for 48-70h.

[0059] In this invention, the amount of seed crystals used is relatively large. Preferably, the mass percentage of the added seed crystals in step (1) is 10-30% of the mass percentage of the silicon source, and more preferably 20-30%. By adopting the above preferred embodiment, it is beneficial to form more crystal nuclei, and the molecular sieve prepared has the characteristic of small crystal grains.

[0060] According to the present invention, preferably, in the mixture described in step (1), the amount of the molecular sieve mother liquor is less than the amount of water. More preferably, the mass percentage of the molecular sieve mother liquor added in step (1) to the total mass of the molecular sieve mother liquor and water in step (1) is not greater than 50%, more preferably 10-30%. In the above preferred cases, it is beneficial to form a molecular sieve with small crystals and a high specific surface area.

[0061] According to the present invention, preferably, in step (4), the acidification deposition includes: adding acid to the molecular sieve mother liquor to adjust the pH value to 5-7, preferably 5-6.5.

[0062] Preferably, the acidification deposition time is 0.5-4 hours.

[0063] In this invention, the selection range for the silicon source, alkali source, aluminum source, and template agent in step (1) is relatively wide, and the above-mentioned raw materials are all conventional choices in the art. The above-mentioned raw materials should generally be mixed into a uniform gel by appropriate means, for example, by stirring.

[0064] According to the present invention, preferably, the silicon source is selected from at least one of silica sol, silica, fumed silica, water glass and tetraethyl orthosilicate; more preferably, silica sol.

[0065] According to the present invention, preferably, the alkali source is selected from alkaline metal salts, and more preferably at least one of sodium hydroxide, potassium hydroxide and calcium hydroxide; more preferably sodium hydroxide.

[0066] According to the present invention, preferably, the aluminum source is selected from at least one of boehmite, aluminum sulfate, aluminum isopropoxide and sodium aluminate; more preferably, it is boehmite.

[0067] According to the present invention, preferably, the template agent is selected from at least one of ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-anetanediamine, hexamethylammonium bromide, hexamethylammonium chloride, and hexamethylammonium hydroxide; more preferably, at least one of 1,6-hexanediamine, hexamethylammonium bromide, hexamethylammonium chloride, and hexamethylammonium hydroxide.

[0068] In this invention, preferably, the seed crystal is a ZSM-48 molecular sieve seed crystal, wherein the molar ratio of silicon oxide to aluminum oxide in the ZSM-48 molecular sieve seed crystal is not less than 40, preferably 45-500. The silicon-aluminum ratio in the ZSM-48 molecular sieve seed crystal mainly depends on the feeding and preparation method of the silicon and aluminum sources in the raw materials.

[0069] Currently, in the XRD diffraction patterns of ZSM-48 molecular sieve raw powder synthesized using existing techniques and calcined, the peak positions are generally at 2θ angles of 7.5°, 21.2°, 22.8°, and 31.3°, with the highest peak at 21°-22° and a weaker peak at 7°-8°. Researchers of this invention have discovered that by employing a specific synthesis method, the preferred ZSM-48 molecular sieve seed crystals of this invention can be prepared. In the X-ray diffraction pattern of these seed crystals after calcination, the relative peak height of the diffraction peak at 2θ angle of 7°-8° is significantly higher than that of the diffraction peak at 7°-8° in molecular sieves obtained using existing techniques. Preferably, in the X-ray diffraction pattern of the calcined ZSM-48 molecular sieve seed crystals, using the peak height of the diffraction peak at 2θ angle of 21°-22° as a reference value, the peak height of the diffraction peak at 2θ angle of 7°-8° is not less than 70% of the reference value, preferably 75%-135%. For example, the lower limit of the peak height range of the 7°-8° diffraction peak can be 75%, 80%, 90% of the reference value, etc., and the upper limit of the peak height range of the 7°-8° diffraction peak can be 135%, 120%, 110%, 100% of the reference value, etc. Due to the influence of factors such as sample and instrument, the specific peak position of the 2θ angle in this invention may have a deviation of ±0.5°. The purpose of calcination is to remove impurities such as template agents in the molecular sieve powder to obtain more accurate XRD characterization results, and it will not have a substantial impact on the diffraction peaks in the XRD pattern of the molecular sieve itself. Therefore, the calcination conditions are based on the removal of impurities. For example, calcination can be carried out at 400-700℃ for 1-8 hours. In the preparation example of this invention, the ZSM-48 molecular sieve seed crystals were calcined at 600℃ for 4 hours before characterization.

[0070] In this invention, preferably, the method for preparing the seed crystal includes: contacting the reaction mixture under crystallization conditions, wherein the reaction mixture includes a silicon source, an alkali source, an aluminum source, a template agent, and water. The selection range of the silicon source, alkali source, aluminum source, and template agent can be the same as described above, and will not be repeated here; the types of silicon source, alkali source, aluminum source, and template agent selected can be the same as those used in the ZSM-48 molecular sieve precursor preparation process described above, or they can be different. Preferably, in the seed crystal preparation process, the content of each component in the reaction mixture satisfies the following relationship:

[0071] R / SiO2 = 0.01-0.5, more preferably 0.01-0.3;

[0072] H2O / SiO2 = 5-50, more preferably 5-20;

[0073] M + / SiO2 = 0.01-0.5, more preferably 0.01-0.15;

[0074] Al2O3 / SiO2 = 0-0.02; more preferably 0.01-0.017;

[0075] Where R represents the template agent, M + Indicates the alkali source.

[0076] In this invention, preferably, the preparation method of the seed crystals mainly includes three crystallization steps, and the temperature of each crystallization step is higher than the temperature of the previous crystallization step. Specifically, the crystallization temperature t1 of the first step satisfies 15℃≤t1<50℃, preferably carried out at room temperature, more preferably 20℃≤t1≤45℃, and the crystallization time of the first step is 5-24h, preferably 6-15h; the crystallization temperature t2 of the second step satisfies 50℃≤t2<100℃, preferably 60℃≤t2≤80℃, and the crystallization time of the second step is 0.5-36h, preferably 5-30h; the crystallization temperature t3 of the third step satisfies 100℃≤t3≤200℃, preferably 120℃≤t3≤190℃, and the crystallization time of the third step is 10-96h, preferably 20-80h. The seed crystals obtained by using the above preferred embodiments are beneficial for obtaining small-grain products in the above-mentioned method for preparing ZSM-48 molecular sieve precursors.

[0077] In this invention, the molding can be carried out using conventional molding methods in the art, such as extrusion molding.

[0078] According to the present invention, preferably, the molding process includes: mixing dried ZSM-48 molecular sieve powder, binder and additives, and then molding and calcining.

[0079] In this invention, the additive can be selected from any molding additive well known to those skilled in the art. Preferably, the additive is an inorganic acid, and more preferably nitric acid and / or hydrochloric acid.

[0080] In this invention, the binder can be selected from a wide range of options, and can be any conventional choice in the art. Preferably, the binder is selected from at least one of alumina, silicon dioxide, boehmite, and silica sol, and more preferably boehmite.

[0081] In this invention, preferably, the amount of the binder is 20-60 parts by weight, more preferably 30-50 parts by weight, relative to 100 parts by weight of dried ZSM-48 molecular sieve powder, and the amount of the additive is 2-20 parts by weight, more preferably 2-10 parts by weight.

[0082] Preferably, the calcination conditions include: a calcination temperature of 500-600℃ and a calcination time of 2-6 hours.

[0083] In this invention, the ammonium exchange in step (2) can be carried out using conventional operations in the art. Preferably, the ammonium exchange in step two includes contacting the molded carrier with an aqueous solution containing ammonium salt.

[0084] Preferably, the ammonium exchange conditions include: a temperature of 70-120℃, more preferably 80-100℃; and a time of 1-8 hours, more preferably 2-5 hours. Under these preferred conditions, it is beneficial to significantly reduce the oxide content in the molecular sieve product, further improve the isomerization performance of the catalyst, and lower the pour point of the product.

[0085] Preferably, the concentration of ammonium salt in the aqueous solution of the ammonium salt is 0.01-1 mol / L, more preferably 0.1-1 mol / L.

[0086] Preferably, the ammonium salt is selected from at least one of ammonium nitrate, ammonium sulfate, ammonium chloride, and ammonium acetate.

[0087] In this invention, the active metal component can be introduced in step three using methods well known to those skilled in the art. Preferably, the product in step two can be impregnated with a solution of a soluble compound containing the active metal component, and then dried and calcined to obtain the hydroisomerization catalyst.

[0088] Preferably, the amount of the soluble compound of the active metal component is such that, based on the total amount of the hydroisomerization catalyst, the content of the active metal component, expressed as an element, is 0.1-20% by weight, preferably 0.2-10% by weight; under the above preferred conditions, it is beneficial to further improve the catalytic activity of the catalyst.

[0089] In this invention, the types of soluble compounds containing active metal components are well known to those skilled in the art and can be conventionally selected in the field. Preferably, the soluble compounds containing active metal components are selected from at least one of tetraamminepalladium nitrate, tetraamminepalladium acetate, dichlorotetraamminepalladium, tetraammineplatinum nitrate, tetraammineplatinum acetate, and dichlorotetraammineplatinum.

[0090] According to the present invention, the drying and calcination can be carried out using conventional operations in the art. Preferably, the drying temperature is 80-120°C and the drying time is 2-6 hours.

[0091] Preferably, the roasting temperature is 400-500℃ and the roasting time is 2-6 hours.

[0092] In this invention, preferably, the preparation method further includes: reducing and activating the hydroisomerization catalyst obtained in step three under a hydrogen atmosphere, wherein the reduction and activation process can be carried out in a manner conventional in the art. Preferably, the reduction temperature is 300-500℃, and the reduction time is 2-6 hours.

[0093] A second aspect of the present invention provides a hydroisomerization catalyst prepared by the above preparation method.

[0094] The third aspect of this invention provides the application of the above-mentioned hydroisomerization catalyst in the hydroisomerization reaction of hydrocarbon oils.

[0095] The present invention will be described in detail below through embodiments.

[0096] In the following examples and comparative examples, the samples were characterized by XRD using a Bruker D5005 diffractometer with Cu Kα rays (λ = 0.154 nm), a tube voltage of 40 kV, a tube current of 30 mA, a scanning range of 5°–35°, a step size of 0.013°, and a step speed of 1 step per second. The morphology and size of the samples were characterized using a Hitachi S-4800 scanning electron microscope (SEM) with an accelerating voltage of 20 kV.

[0097] The composition of the samples, including the content of alkali metal oxides, was determined using a Rigaku Electric Industries, Ltd. (RIGE) 3271E X-ray fluorescence spectrometer (XRF) from Japan. Sample preparation was performed using a pellet method, and the measurement conditions were a rhodium target with an end window, a tube voltage of 50 kV, and a tube current of 50 mA.

[0098] The pore structure parameters of the product, such as specific surface area and pore volume, were measured using nitrogen adsorption and BET methods.

[0099] The following preparation examples illustrate the preparation of seed crystals.

[0100] Preparation Example 1-1

[0101] Aluminum sulfate, hexamethyldiamine hydroxide (HMOH), sodium hydroxide, and deionized water were mixed in a certain proportion and stirred for 30 minutes. Silica sol was then added. The molar ratio of each substance was n(Al₂O₃):(HMOH):n(Na₂O₃). + The mixture of n(H₂O):n(SiO₂) = 0.01:0.03:0.3:8:1 was transferred to a crystallization vessel and crystallized at room temperature with stirring at 400 rpm for 6 hours; then crystallized at 80℃ for 24 hours, followed by crystallization at 180℃ for 48 hours. After crystallization, the mixture was filtered, and the solid product was dried at 120℃ for 6 hours to obtain seed crystal A1. Seed crystal A1 was calcined at 600℃ for 4 hours, and the XRD diffraction peaks were observed. Figure 1The peak height of the diffraction peak at 7°-8° is 108% of the peak height of the diffraction peak at 21°-22°. The XRF analysis results and data such as specific surface area are shown in Table 1.

[0102] Preparation Examples 1-2

[0103] Sodium aluminate, hexamethyldiamine chloride (HMCl), sodium hydroxide, and deionized water were mixed in a certain proportion and stirred for 30 minutes. Silica sol was then added. The molar ratio of each substance was n(Al₂O₃):(HMCl):n(Na₂O₃). + The mixture of n(H₂O):n(SiO₂) = 0.004:0.03:0.3:21:1 was transferred into a crystallization vessel and crystallized at room temperature with stirring at 350 rpm for 12 h; then at 60 °C for 12 h, and then at 160 °C for 48 h. After crystallization, the mixture was filtered, and the product was dried at 120 °C for 6 h. The product obtained after filtration and drying was seed crystal A2. After calcination at 600 °C for 4 h, the peak height of the 7°-8° diffraction peak was 115% of the peak height of the 21°-22° diffraction peak in the XRD diffraction. The XRF analysis results and specific surface area data are shown in Table 1.

[0104] Preparation Examples 1-3

[0105] Sodium aluminate, hexamethyldiamine chloride (HMCl), sodium hydroxide, and deionized water were mixed in a certain proportion and stirred for 30 minutes. Silica sol was then added. The molar ratio of each substance was n(Al₂O₃):(HMCl):n(Na₂O₃). + The mixture of n(H₂O):n(SiO₂) = 0.004:0.03:0.3:21:1 was transferred to a crystallization vessel and crystallized at room temperature with stirring at 350 rpm for 12 hours. After crystallization, it was crystallized at 170℃ for 60 hours. The product obtained after filtration and drying was seed crystal A3. XRD analysis of seed crystal A3 after calcination at 600℃ for 4 hours is shown in the figure. Figure 2 The peak height of the diffraction peak at 7°-8° is 63% of that at 21°-22°. The XRF analysis results and data such as specific surface area are shown in Table 1.

[0106] The following preparation examples illustrate the preparation of ZSM-48 molecular sieves.

[0107] Preparation Example 2-1

[0108] (1) Aluminum sulfate, hexamethyldiamine chloride (HMCl), sodium hydroxide, and deionized water containing molecular sieve mother liquor were mixed in a certain proportion and stirred for 30 minutes before adding silica sol. The molar ratio of each substance was n(Al2O3):(HMCl):n(Na) +):n(H2O):n(SiO2)=0.01:0.03:0.3:10:1. The mass percentage of the molecular sieve mother liquor added in step (1) is 30% of the total mass of the molecular sieve mother liquor and water, and 25% of the mass of SiO2 is added as ZSM-48 seed crystal A1;

[0109] (2) Transfer the above mixture into a crystallization kettle, stir at room temperature for 6 hours, crystallize at 80°C for 24 hours, and crystallize at 170°C for 48 hours;

[0110] (3) After crystallization, filter and dry at 120℃ for 6 hours to obtain ZSM-48 molecular sieve powder Z-1. Return the molecular sieve mother liquor to step (1). The water content of Z-1 is 5wt%.

[0111] The XRF analysis results of the silicon-to-aluminum ratio and specific surface area of ​​Z-1 are shown in Table 1. Scanning electron microscope images are shown below. Figure 3 Its morphology is ellipsoidal, with a major axis of 300-700 nm and a major axis to minor axis ratio of approximately 1.1-1.4:1.

[0112] Preparation Example 2-2

[0113] (1) Sodium aluminate, hexamethyldiamine chloride (HMCl), sodium hydroxide, and deionized water containing molecular sieve mother liquor are mixed in a certain proportion and stirred for 30 minutes before adding silica sol. The molar ratio of each substance is n(Al2O3):(HMCl):n(Na) + ):n(H2O):n(SiO2)=0.004:0.03:0.3:20:1, the mass percentage of the molecular sieve mother liquor added in step (1) is 20% of the total mass of the molecular sieve mother liquor and water, and 15% of the mass of SiO2 is added as ZSM-48 seed crystal A2;

[0114] (2) The above mixture was transferred into a crystallization vessel and crystallized at 40°C for 12 hours, at 80°C for 10 hours, and at 170°C for 48 hours.

[0115] (3) After crystallization, filter and dry at 120℃ for 6 hours to obtain dried powder of ZSM-48 molecular sieve Z-2. Return the molecular sieve mother liquor to step (1). The water content of Z-2 is 6wt%.

[0116] The XRF analysis results of the silicon-to-aluminum ratio of Z-2 and its specific surface area are shown in Table 1. Its morphology is ellipsoidal, with a major axis of 300-600 nm and a major axis-to-minor axis ratio of approximately 1.1-1.4:1.

[0117] Comparative Preparation Example 1

[0118] (1) Aluminum sulfate, hexamethyldiamine chloride (HMCl), sodium hydroxide, and deionized water containing molecular sieve mother liquor were mixed in a certain proportion and stirred for 30 minutes before adding silica sol. The molar ratio of each substance was n(Al2O3):(HMCl):n(Na) + ):n(H2O):n(SiO2)=0.0125:0.03:0.3:30:1. Add 25% of the mass of SiO2 ZSM-48 seed crystal A3. The mass percentage of the molecular sieve mother liquor added in step (1) to the total mass of the molecular sieve mother liquor and water is 20%;

[0119] (2) Transfer the above mixture into a crystallization kettle, stir at room temperature for 6 hours, crystallize at 80°C for 24 hours, and crystallize at 170°C for 48 hours;

[0120] (3) After crystallization, filter and dry at 120℃ for 6 hours to obtain dried powder of ZSM-48 molecular sieve DZ-1. Return the molecular sieve mother liquor to step (1). The water content of DZ-1 is 8wt%.

[0121] The XRF analysis results and specific surface area data of DZ-1 are shown in Table 1. Its morphology is rod-shaped with a length-to-short diameter ratio of approximately 7:1.

[0122] Table 1

[0123]

[0124] The following examples illustrate the preparation of hydroisomerization catalysts.

[0125] Example 1

[0126] 70 g of sample Z-1 from Preparation Example 2-1 was mixed with 40 g of boehmite (dry basis) and 2 g of nitric acid solution, shaped, and calcined at 580°C for 3 h. The carrier strip was then placed in a 0.5 M ammonium chloride solution and exchanged at 90°C for 2 h. The carrier strip was removed, dried, and the sodium oxide content was measured; the results are shown in Table 2.

[0127] Dichlorotetraammineplatinum (containing 57.3% Pt by mass) was poured into 100 g of deionized water and stirred until homogeneous. 100 g of support was added to the above solution and impregnated at room temperature for 4 hours. Subsequently, the catalyst precursor was dried at 120°C for 4 hours. It was then calcined under an air stream at 450°C for 4 hours. The semi-finished catalyst was then reduced again in a hydrogen atmosphere at 400°C for 4 hours to obtain the final catalyst. The obtained catalyst was named CAT-1. The Pt loading in the catalyst was 0.5 wt%.

[0128] Example 2

[0129] Following the method of Example 1, except that Z-1 was replaced with Z-2 from Preparation Example 2-2, the support strip was removed after ammonium exchange, dried, and the sodium oxide content was measured. The results are shown in Table 2. The obtained catalyst was named CAT-2.

[0130] Example 3

[0131] 70 g of sample Z-1 from Preparation Example 2-1 was mixed with 40 g of boehmite (dry basis) and 2 g of nitric acid solution, shaped, and calcined at 580°C for 3 h. The carrier strip was then placed in a 0.3 M ammonium chloride solution and exchanged at 85°C for 1.5 h. The carrier strip was removed, dried, and the sodium oxide content was measured; the results are shown in Table 2.

[0132] Dichlorotetraammineplatinum (containing 57.3% Pt by mass) was poured into 100 g of deionized water and stirred until homogeneous. 100 g of support was added to the above solution and impregnated at room temperature for 4 hours. Subsequently, the catalyst precursor was dried at 120°C for 4 hours. It was then calcined under an air stream at 450°C for 4 hours. The semi-finished catalyst was then reduced again in a hydrogen atmosphere at 400°C for 4 hours to obtain the final catalyst. The obtained catalyst was named CAT-3. The Pt loading in the catalyst was 0.5 wt%.

[0133] Example 4

[0134] 70 g of sample Z-1 from Preparation Example 2-1 was mixed with 40 g of boehmite (dry basis) and 1 g of nitric acid solution, shaped, and calcined at 580°C for 3 h. The carrier strip was then placed in a 0.5 M ammonium chloride solution and exchanged at 70°C for 1 h. The carrier strip was removed, dried, and the sodium oxide content was measured; the results are shown in Table 2.

[0135] Dichlorotetraammineplatinum (containing 57.3% Pt by mass) was poured into 100 g of deionized water and stirred until homogeneous. 100 g of support was added to the above solution and impregnated at room temperature for 4 hours. Subsequently, the catalyst precursor was dried at 120°C for 4 hours. It was then calcined under an air stream at 350°C for 4 hours. The semi-finished catalyst was then reduced again in a hydrogen atmosphere at 350°C for 4 hours to obtain the final catalyst. The obtained catalyst was named CAT-4. The Pt loading in the catalyst was 0.5 wt%.

[0136] Comparative Example 1

[0137] Following the method of Example 1, except that Z-1 was replaced with DZ-1 from Comparative Preparation Example 1, the support strip was removed after ammonium exchange, dried, and the sodium oxide content was measured. The results are shown in Table 1. The obtained catalyst was named DCAT-1.

[0138] Comparative Example 2

[0139] Following the method of Example 1, except that the Z-1 sample of Preparation Example 2-1 was calcined at 580 degrees Celsius for 3 hours, and the resulting solid was first subjected to ammonium exchange and then extruded into strips. The sodium oxide content was measured, and the results are shown in Table 1. The obtained catalyst was named DCAT-2.

[0140] Table 2

[0141]

[0142] The catalysts described above were evaluated using the following evaluation methods:

[0143] 200 mL of each of the above catalysts CAT-1, CAT-2, CAT-3, CAT-4, DCAT-1, and DCAT-2 were respectively loaded into a high-pressure hydrotreating reactor. Hydrocracking tail oil feedstock was injected into the reactor from top to bottom for reaction. The feedstock properties and reaction conditions are shown in Tables 3 and 4, respectively. After the reaction, the product was distilled to remove light components below 370 degrees Celsius. The components above 370 degrees Celsius were analyzed, and their yields were calculated. The results are shown in Table 5.

[0144] Table 3 Properties of Hydrocracking Tail Oil

[0145] Analysis item Analysis data Analysis method 20 °C density / (kg / m 3 )]]> 840.8 SH / T 0604-2000 Kinematic viscosity at 40°C / mm 2 2s -1 )]]> GB / T 265-1988 40℃ 7.0 100℃ 4.6 Pour point / ℃ +40 SH / T 0771-2005 Nitrogen mass fraction / (μg / g) ＜1 NB / SH / T 0704-2010 Sulfur mass fraction / (μg / g) 3.0 SH / T 0842-2010 Distillation range / ℃ ASTM D-1160 IBP 329 10％ 374 50％ 431 90％ 496 FBP 544

[0146] Table 4 Reaction conditions

[0147]

[0148]

[0149] Table 5 Evaluation results at 320℃

[0150] Catalyst Product yield / % Product pour point / ℃ Product viscosity index CAT-1 73 -19 118 CAT-2 75 -18 117 CAT-3 74 -18 115 CAT-4 68 -17 110 DCAT-1 63 -15 105 DCAT-2 62 -14 106

[0151] The results in Tables 1 and 5 show that the hydroisomerization catalyst provided by this invention is based on a ZSM-48 molecular sieve with a specific structure and has an extremely low alkali metal content. As a result, the hydroisomerization catalyst has higher catalytic activity in the hydroisomerization reaction of hydrocarbon oils.

[0152] The preparation method of this invention has a short preparation process and is simple to operate. By first forming and then exchanging ammonium, the post-processing is easy and can significantly reduce the alkali metal content in the catalyst and improve the catalytic activity of the catalyst.

[0153] 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 inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A hydroisomerization catalyst, comprising a support and an active metal component supported on the support, wherein the support contains a ZSM-48 molecular sieve, wherein the molar ratio of silica to alumina in the ZSM-48 molecular sieve is not less than 40, and the specific surface area of ​​the ZSM-48 molecular sieve is not less than 200 m². 2 / g, the ZSM-48 molecular sieve crystals are ellipsoidal, with a major axis not exceeding 700nm and a major axis to minor axis ratio of 1-3:1; The active metal component is Pt and / or Pd; in, Based on the total amount of the carrier, the content of alkaline metal oxides in the carrier is not higher than 0.001 wt%. The preparation method of the ZSM-48 molecular sieve includes the following steps: (1) Provide a mixture containing silicon source, alkali source, aluminum source, template agent, water and molecular sieve mother liquor and seed crystals; (2) The mixture is subjected to a crystallization reaction; the conditions for the crystallization reaction include: reacting at 20℃-50℃ for 1-20h, reacting at 50℃-80℃ for 1-34h, and then reacting at 80℃-180℃ for 1-70h. (3) The mixture obtained from the crystallization reaction in step (2) is subjected to solid-liquid separation to obtain ZSM-48 molecular sieve and molecular sieve mother liquor. The molecular sieve mother liquor is returned to step (1). The method further includes, optionally, step (4), which includes: acidifying and depositing the molecular sieve mother liquor, then performing solid-liquid separation, and returning the filtrate to step (1). In step (1), the mass percentage of the added seed crystals is 15-30% of the mass of the silicon source, and the silicon source is SiO2. The seed crystal is a ZSM-48 molecular sieve seed crystal, and the molar ratio of silicon oxide to aluminum oxide in the ZSM-48 molecular sieve seed crystal is 45-500.

2. The hydroisomerization catalyst according to claim 1, wherein, Based on the mass of the catalyst, the content of molecular sieve on a dry basis is 20-80% by weight.

3. The hydroisomerization catalyst according to claim 2, wherein, Based on the mass of the catalyst, the content of molecular sieve on a dry basis is 30-70% by weight.

4. The hydroisomerization catalyst according to claim 1, wherein, Based on the total amount of catalyst, the content of the active metal component is 0.1-20% by weight, expressed as an element.

5. The hydroisomerization catalyst according to claim 4, wherein, Based on the total amount of catalyst, the content of the active metal component is 0.2-10% by weight, expressed as an element.

6. The hydroisomerization catalyst according to claim 1, wherein, The catalyst also contains a binder.

7. The hydroisomerization catalyst according to claim 6, wherein, The binder is aluminum oxide and / or silicon oxide.

8. The hydroisomerization catalyst according to claim 6 or 7, wherein the binder content is 20-80% by weight based on the total amount of catalyst.

9. The hydroisomerization catalyst according to claim 1 or 2, wherein, The ZSM-48 molecular sieve has a length-to-short diameter ratio of 1-2:

1.

10. The hydroisomerization catalyst according to claim 1 or 2, wherein, The ZSM-48 molecular sieve has a crystal size of 300-700 nm.

11. The hydroisomerization catalyst according to claim 10, wherein, The ZSM-48 molecular sieve has a crystal size of 400-600 nm.

12. The hydroisomerization catalyst according to any one of claims 1-3, wherein, The specific surface area of ​​the ZSM-48 molecular sieve is 200-280 m². 2 / g.

13. The hydroisomerization catalyst according to any one of claims 1-3, wherein, The pore volume of ZSM-48 molecular sieve is 0.2-0.3 mL / g.

14. A method for preparing a hydroisomerization catalyst, characterized in that, Includes the following steps: Step 1: Shape the dried powder of ZSM-48 molecular sieve into a molded carrier; The molar ratio of silica to alumina in the ZSM-48 molecular sieve is not less than 40, and the specific surface area of ​​the ZSM-48 molecular sieve is not less than 200 m². 2 / g, the ZSM-48 molecular sieve crystals are ellipsoidal, with a major axis not exceeding 700nm and a major axis to minor axis ratio of 1-3:1; Specifically, based on the mass of the dried ZSM-48 molecular sieve powder, the moisture content of the dried ZSM-48 molecular sieve powder is less than 15 wt%. Step 2: Perform ammonium exchange on the molded carrier; Step 3: Introduce an active metal component onto the product obtained in Step 2 to obtain a hydroisomerization catalyst; based on the total amount of support in the hydroisomerization catalyst, the content of basic metal oxides in the support shall not exceed 0.001 wt%. The active metal component is Pt and / or Pd; The preparation method of the ZSM-48 molecular sieve includes the following steps: (1) Provide a mixture containing silicon source, alkali source, aluminum source, template agent, water and molecular sieve mother liquor and seed crystals; (2) The mixture is subjected to a crystallization reaction; the conditions for the crystallization reaction include: reacting at 20℃-50℃ for 1-20h, reacting at 50℃-80℃ for 1-34h, and then reacting at 80℃-180℃ for 1-70h. (3) The mixture obtained from the crystallization reaction in step (2) is subjected to solid-liquid separation to obtain ZSM-48 molecular sieve and molecular sieve mother liquor. The molecular sieve mother liquor is returned to step (1). The method further includes, optionally, step (4), which includes: acidifying and depositing the molecular sieve mother liquor, then performing solid-liquid separation, and returning the filtrate to step (1). In step (1), the mass percentage of the added seed crystals is 15-30% of the mass of the silicon source, and the silicon source is SiO2. The seed crystal is a ZSM-48 molecular sieve seed crystal, and the molar ratio of silicon oxide to aluminum oxide in the ZSM-48 molecular sieve seed crystal is 45-500.

15. The preparation method according to claim 14, wherein, The composition of each component in the mixture in step (1), calculated by molar amount, satisfies the following relationship: R / SiO2 = 0.01-0.4; M + / SiO2=0.01-0.4; Al2O3 / SiO2 = 0-0.02; H2O / SiO2 = 5-30; Wherein, SiO2 refers to SiO2 in the silicon source, R represents the template agent, and M... + Indicates the alkali source.

16. The preparation method according to claim 15, wherein, The composition of each component in the mixture in step (1), calculated by molar amount, satisfies the following relationship: R / SiO2 = 0.01-0.08; M + / SiO2=0.1-0.2; Al2O3 / SiO2 = 0.01-0.015; H2O / SiO2 = 5-20; Wherein, SiO2 refers to SiO2 in the silicon source, R represents the template agent, and M... + Indicates the alkali source.

17. The preparation method according to claim 14, wherein, The conditions for the crystallization reaction in step (2) include: reacting at 20℃-50℃ for 6-20h, reacting at 50℃-80℃ for 12-34h, and then reacting at 80℃-180℃ for 48-70h.

18. The preparation method according to claim 14, wherein, The mass percentage of the molecular sieve mother liquor added in step (1) is no more than 50% of the total mass of the molecular sieve mother liquor and water in step (1).

19. The preparation method according to claim 18, wherein, The mass percentage of the molecular sieve mother liquor added in step (1) is 10-30% of the total mass of the molecular sieve mother liquor and water in step (1).

20. The preparation method according to claim 14, wherein, In step (4), the acidification deposition includes: adding acid to the molecular sieve mother liquor and adjusting the pH value to 5-7.

21. The preparation method according to claim 20, wherein, In step (4), the acidification deposition includes adding acid to the molecular sieve mother liquor and adjusting the pH value to 5-6.

5.

22. The preparation method according to claim 14, wherein, The acidification deposition time is 0.5-4 hours.

23. The preparation method according to claim 14, wherein, The silicon source is selected from at least one of silica, fumed silica, silica sol, water glass, and tetraethyl orthosilicate. And / or, the alkali source is an alkaline metal salt; And / or, the aluminum source is selected from at least one of boehmite, aluminum isopropoxide, aluminum sulfate, and sodium aluminate; And / or, the template agent is selected from at least one of ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-anetanediamine, hexamethylammonium hydroxide, hexamethylammonium chloride, and hexamethylammonium bromide.

24. The preparation method according to claim 14, wherein, The alkali source is selected from at least one of calcium hydroxide, potassium hydroxide, and sodium hydroxide.

25. The preparation method according to claim 14, wherein, In the X-ray diffraction pattern of the ZSM-48 molecular sieve seed crystals after calcination, the peak height of the diffraction peak with a 2θ angle of 21°-22° is taken as the reference value, and the peak height of the diffraction peak with a 2θ angle of 7°-8° is not less than 70% of the reference value.

26. The preparation method according to claim 25, wherein, In the X-ray diffraction pattern of the ZSM-48 molecular sieve seed crystals after calcination, the peak height of the diffraction peak with a 2θ angle of 21°-22° is taken as the reference value, and the peak height of the diffraction peak with a 2θ angle of 7°-8° is taken as 75%-135% of the reference value.

27. The preparation method according to claim 25 or 26, wherein, The method for preparing the seed crystals includes contacting the reaction mixture under crystallization conditions. The reaction mixture includes a silicon source, an alkali source, an aluminum source, a template agent, and water. The crystallization conditions include: crystallizing sequentially at temperature t1 for 5-24 hours, at temperature t2 for 0.5-36 hours, and at temperature t3 for 10-96 hours, with 15℃≤t1<50℃, 50℃≤t2<100℃, and 100℃≤t3≤200℃.

28. The preparation method according to claim 14, wherein, The molding process includes mixing dried ZSM-48 molecular sieve powder, binder, and additives, followed by molding and calcination.

29. The preparation method according to claim 28, wherein, The additive is an inorganic acid.

30. The preparation method according to claim 29, wherein, The auxiliary agent is nitric acid and / or hydrochloric acid.

31. The preparation method according to claim 28, wherein, The binder is selected from at least one of alumina, silica, boehmite, and silica sol.

32. The preparation method according to claim 31, wherein, The binder is boehmite.

33. The preparation method according to claim 28, wherein, The amount of the binder is 20-60 parts by weight relative to 100 parts by weight of dried ZSM-48 molecular sieve powder, and the amount of the additive is 2-20 parts by weight.

34. The preparation method according to claim 33, wherein, The amount of the binder is 30-50 parts by weight relative to 100 parts by weight of dried ZSM-48 molecular sieve powder, and the amount of the additive is 2-10 parts by weight.

35. The preparation method according to claim 28, wherein, The calcination conditions include: a calcination temperature of 300-600℃ and a calcination time of 2-10h.

36. The preparation method according to claim 14, wherein, The ammonium exchange in step two includes contacting the molded carrier with an aqueous solution containing ammonium salt.

37. The preparation method according to claim 36, wherein, The conditions for ammonium exchange include: a temperature of 70-120℃ and a time of 1-8h.

38. The preparation method according to claim 36, wherein, The concentration of ammonium salt in the aqueous solution is 0.01-1 mol / L.

39. The preparation method according to claim 36, wherein, The ammonium salt is selected from at least one of ammonium nitrate, ammonium sulfate, ammonium chloride, and ammonium acetate.

40. The preparation method according to claim 14, wherein, The method for introducing the active metal component in step three includes: impregnating the product from step two with a solution of a soluble compound containing the active metal component, followed by drying and calcination to obtain the hydroisomerization catalyst.

41. The preparation method according to claim 40, wherein, The amount of the soluble compound of the active metal component is such that, based on the total amount of the hydroisomerization catalyst, the content of the active metal component is 0.1-20% by weight in terms of elements.

42. The preparation method according to claim 41, wherein, The amount of the soluble compound of the active metal component is such that, based on the total amount of the hydroisomerization catalyst, the content of the active metal component is 0.2-10% by weight in terms of elements.

43. The preparation method according to claim 40, wherein, The soluble compound containing the active metal component is selected from at least one of tetraamminepalladium nitrate, tetraamminepalladium acetate, dichlorotetraamminepalladium, tetraammineplatinum nitrate, tetraammineplatinum acetate, and dichlorotetraammineplatinum.

44. The preparation method according to claim 40, wherein, The drying temperature is 80-120℃, and the drying time is 2-6 hours.

45. The preparation method according to claim 40, wherein, The roasting temperature is 400-500℃, and the roasting time is 2-6 hours.

46. ​​The hydroisomerization catalyst prepared by the preparation method according to any one of claims 14-45.

47. The use of the hydroisomerization catalyst according to any one of claims 1-13 and 46 in the hydroisomerization reaction of hydrocarbon oils.

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