Molecular sieve and preparation method thereof, hydroisomerization cracking catalyst and hydrocarbon oil hydroisomerization cracking treatment method

Abstract

The present invention relates to the field of molecular sieves, and discloses a ZSM-48 molecular sieve and a preparation method thereof, a hydroisomerization cracking catalyst and a hydrocarbon oil hydroisomerization cracking treatment method, wherein the molar ratio of silicon oxide to aluminum oxide in the ZSM-48 molecular sieve is not less than 40, and the specific surface area of ​​the ZSM-48 molecular sieve is not more than 200m 2 / g, the ZSM‑48 molecular sieve is ellipsoidal, the long diameter does not exceed 700nm and the ratio of long to short diameter is 1‑3:1. Through the recycling of molecular sieve mother liquor and the introduction of crystal seeds, after three stages of crystallization processes at different temperatures, the progress and temperature of the crystallization reaction are strictly controlled to prepare a ZSM‑48 molecular sieve with an ellipsoidal morphology and a small specific surface area. When the catalyst prepared by the molecular sieve is used in the production of bio-jet fuel, the product yield is higher and the freezing point is lower.

Description

Technical Field

[0001] The present invention relates to the field of molecular sieves, and in particular to a molecular sieve and a preparation method thereof, a hydroisomerization cracking catalyst and a hydrocarbon oil hydroisomerization cracking treatment method. Background Art

[0002] ZSM-48 molecular sieve is a new type of high-silicon molecular sieve developed in the 1980s. It has a two-dimensional ten-membered ring channel structure and belongs to the orthorhombic crystal system. The channels are connected by five-membered rings, and the pore diameter is about 0.6nm. It is characterized by a high silicon-aluminum molar ratio and tubular linear channels, which can accommodate organic molecules with a smaller kinetic radius than benzene. In theory, ZSM-48 molecular sieve has a smaller channel "self-resistance effect". At present, many synthesis methods of ZSM-48 molecular sieves have been reported at home and abroad.

[0003] ZSM-48 molecular sieve was first discovered in the heterocrystals generated by epitaxy of ZSM-39 octahedrons, and then pure phase ZSM-48 was synthesized in the system of silicon source, aluminum source, tetramethylammonium ion and n-propylamine. In 1983, US4397827 first disclosed the synthesis of ZSM-48 molecular sieve, the template used was C2-C12 alkylamine, preferably a mixture of C3-C5 alkylamine and tetramethylammonium hydroxide, and the synthesized ZSM-48 molecular sieve had a silicon-aluminum ratio (SiO2 / Al2O3, the same below) ranging from 25-∞. The synthesized ZSM-48 molecular sieve has a needle-shaped or rod-shaped morphology, and there is a trace amount of octahedral metastable ZSM-48 precursor in the product. Subsequent research results show that when tetramethylammonium ions are used as templates, NaOH is used as an alkali source, and no seed or other templates are added, the main product synthesized is ZSM-39 molecular sieve, and pure phase ZSM-48 molecular sieve cannot be synthesized. US4423021 discloses a method for synthesizing a high silicon-to-aluminum ratio ZSM-48 molecular sieve using a C4-C12 diamine as a template. Since a different organic template is used from US4397827, the product contains no aluminum or a small amount of aluminum, and its silicon-to-aluminum ratio ranges from 50-∞, preferably from 100-∞.

[0004] In addition to the above-mentioned relatively simple templates, some complex templates are also disclosed. EP-A-142317 discloses the synthesis of ZSM-48 molecular sieve in the presence of a specific linear diquaternary ammonium compound having the following general formula: [(R)3N + (Z)m[(R)3N + ](X -)2, wherein each R is an alkyl or heteroalkyl group having 1-20 carbon atoms, a cycloalkyl or cycloheteroalkyl group having 3-6 carbon atoms, or an aryl or heteroaryl group, Z is an alkylene or heteroalkylene group having 1-20 carbon atoms, an alkenylene or heteroalkenylene group having 2-20 carbon atoms, or an arylene metal or heteroarylene group, m is 5, 6, 8, 9 or 10, and X- is an anion. CN102910642A discloses a method for synthesizing ZSM-48 molecular sieves using dibromohexane, trimethylamine and ethanol as templates, which has the characteristics of low synthesis cost and a silicon-aluminum ratio range of 150-500.

[0005] CN102245294B discloses a method for dewaxing a hydrocarbon feedstock containing a waxy component, the method comprising contacting the feedstock with a catalyst system comprising ZSM-48 and a MTT framework structure type molecular sieve under dewaxing conditions. The ZSM-48 has a silica to alumina molar ratio of less than 100, wherein the MTT framework structure type molecular sieve has a silica to alumina molar ratio of less than 45, wherein the MTT framework structure type molecular sieve is ZSM-23, and wherein the ratio of ZSM-48 to ZSM-23 is at least 75:25.

[0006] In summary, although the existing technology can synthesize ZSM-48 molecular sieves, little attention is paid to the morphology and size control of ZSM-48 molecular sieves, the recycling of mother liquor, and the application in hydroisomerization cracking reactions. Summary of the invention

[0007] The purpose of the present invention is to overcome the lack of research on the morphology and size control of ZSM-48 molecular sieves and the recycling of mother liquor in the prior art. The prepared catalyst is used in an isomerization cracking reaction. A ZSM-48 molecular sieve and a preparation method thereof, a hydroisomerization cracking catalyst and a hydrocarbon oil hydroisomerization cracking treatment method are provided. The molecular sieve has an ellipsoidal morphology and a small specific surface area. When the molecular sieve is used for bio-jet fuel reforming, the product yield is higher and the low-temperature flowability is better.

[0008] In order to achieve the above object, the present invention provides a ZSM-48 molecular sieve in the first aspect, wherein the molar ratio of silicon oxide to aluminum oxide in the ZSM-48 molecular sieve is not less than 40, and the specific surface area of ​​the ZSM-48 molecular sieve is not higher than 200m 2 / g, the ZSM-48 molecular sieve is ellipsoidal, the major diameter does not exceed 700nm and the ratio of major diameter to minor diameter is 1-3:1.

[0009] The second aspect of the present invention provides a method for preparing a ZSM-48 molecular sieve, the method comprising the following steps:

[0010] (1) providing a mixture containing a silicon source, an alkali source, an aluminum source, a template, a molecular sieve mother liquid, and a ZSM-48 molecular sieve seed crystal;

[0011] (2) subjecting the mixture to a crystallization reaction; the conditions of the crystallization reaction include: reacting at 20° C.-50° C. for 1-24 h, reacting at 50° C.-80° C. for 0.5-36 h, and then reacting at 80° C.-180° C. for 0.5-72 h;

[0012] (3-1) 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, and the molecular sieve mother liquor is returned to step (1); and / or

[0013] (3-2) The mixture obtained from the crystallization reaction in step (2) is subjected to solid-liquid separation to obtain a product and a molecular sieve mother liquor. The molecular sieve mother liquor is subjected to acidification and precipitation, and then subjected to solid-liquid separation. The obtained acidified mother liquor is returned to step (1).

[0014] The third aspect of the present invention provides a hydroisomerization cracking catalyst, comprising a carrier and an active metal supported on the carrier, wherein the carrier comprises the ZSM-48 molecular sieve provided in the first aspect or the ZSM-48 molecular sieve prepared by the preparation method provided in the second aspect.

[0015] The fourth aspect of the present invention provides a hydrocarbon oil hydroisomerization cracking treatment method, comprising: contacting a feedstock oil with a hydroisomerization cracking catalyst under hydroisomerization conditions, wherein the feedstock oil is a bio-jet fuel production feedstock, and the hydroisomerization cracking catalyst is the hydroisomerization cracking catalyst provided in the third aspect;

[0016] Through the above technical solution, the ZSM-48 molecular sieve described in the present invention has an ellipsoidal morphology. When the molecular sieve is used for bio-jet fuel reforming, the product yield is high and the freezing point is lower. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is the X-ray diffraction pattern of the ZSM-48 molecular sieve in Preparation Example 1;

[0018] Figure 2 is a SEM image of the ZSM-48 molecular sieve in Preparation Example 1;

[0019] Figure 3 This is the SEM image of the ZSM-48 molecular sieve in Comparative Preparation Example 2. DETAILED DESCRIPTION

[0020] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the 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 as specifically disclosed in this article.

[0021] The first aspect of the present invention provides a ZSM-48 molecular sieve, wherein the molar ratio of silicon oxide to aluminum oxide in the ZSM-48 molecular sieve is not less than 40, and the specific surface area of ​​the ZSM-48 molecular sieve is not more than 200m 2 / g, the ZSM-48 molecular sieve is ellipsoidal, the major diameter does not exceed 700nm and the aspect ratio is 1-3:1.

[0022] The ZSM-48 molecular sieve of the present invention has a characteristic ellipsoidal morphology and a small specific surface area. When the molecular sieve is applied to the production of bio-jet fuel, the product yield is higher and the freezing point is lower.

[0023] According to a preferred embodiment of the present invention, the specific surface area of ​​the ZSM-48 molecular sieve is 150-200m 2 / g.

[0024] Preferably, the pore volume of the ZSM-48 molecular sieve is 0.15-0.20 ml / g.

[0025] The second aspect of the present invention provides a method for preparing a ZSM-48 molecular sieve, the method comprising the following steps:

[0026] (1) providing a mixture containing a silicon source, an alkali source, an aluminum source, a template, a molecular sieve mother liquid, and a ZSM-48 molecular sieve seed crystal;

[0027] (2) subjecting the mixture to a crystallization reaction; the conditions of the crystallization reaction include: reacting at 20° C.-50° C. for 1-24 h, reacting at 50° C.-80° C. for 0.5-36 h, and then reacting at 80° C.-180° C. for 0.5-72 h;

[0028] (3-1) 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, and the molecular sieve mother liquor is returned to step (1); and / or

[0029] (3-2) The mixture obtained from the crystallization reaction in step (2) is subjected to solid-liquid separation to obtain a product and a molecular sieve mother liquor. The molecular sieve mother liquor is subjected to acidification and precipitation, and then subjected to solid-liquid separation. The obtained acidified mother liquor is returned to step (1).

[0030] According to the present invention, the formation of small-grained ZSM-48 is facilitated by recycling the molecular sieve mother liquor and introducing crystal seeds. It is worth noting that the progress and temperature of the crystallization reaction are strictly controlled through three stages of crystallization processes at different temperatures in the present invention. Compared with the prior art, the crystallization reaction process is set at a low temperature, which is further conducive to the formation of small-grained ZSM-48.

[0031] In the present invention, it is understood by those skilled in the art that the molecular sieve mother liquor can be obtained by arbitrarily selecting one of the above steps (3-1) and (3-2) or both of them. When the method provided by the present invention includes step (3-2), it is understood by those skilled in the art that the acidified mother liquor provides at least part of the molecular sieve mother liquor described in step (1).

[0032] Preferably, the molecular sieve mother liquor obtained by the method of step (3-2) is returned to step (1). Under the above preferred embodiment, it is conducive to the formation of small-grained ZSM-48.

[0033] In the present invention, the ratio of each raw material in the reactants has a certain influence on the final performance of the molecular sieve. According to a preferred embodiment of the present invention, specifically, the composition of each component in the mixture in step (1) calculated by molar amount satisfies the following relationship:

[0034] R / SiO2=0.01-0.50, preferably 0.01-0.1;

[0035] Molecular sieve mother liquor / SiO2=5-50, preferably 5-30;

[0036] M + / SiO2=0.01-0.50, preferably 0.1-0.3;

[0037] Al2O3 / SiO2=0-0.03, preferably 0.01-0.025; wherein SiO2 refers to SiO2 in the silicon source, R represents the template, and M + It represents the alkali source. The molar amount of the molecular sieve mother liquor is calculated based on pure water, which is the mass of the molecular sieve mother liquor / 18.

[0038] According to a preferred embodiment of the present invention, step (1) of the method does not include the addition of additional water. It can be understood by those skilled in the art that, in the preparation method of the ZSM-48 molecular sieve, except for the solvent water or crystal water that may exist in the silicon source, alkali source, and aluminum source, no additional water needs to be introduced in the entire preparation process. The above preferred embodiment is adopted to facilitate the formation of small-grained ZSM-48.

[0039] The silicon source, alkali source, aluminum source and template agent in step (1) of the present invention have a wide range of choices, and the above raw materials are conventionally selected in the art. The above raw materials should generally be mixed into a uniform colloid by corresponding means, for example, by stirring.

[0040] According to a preferred embodiment of the present invention, the silicon source is selected from at least one of silica sol, white carbon black, fumed silica, water glass and tetraethyl orthosilicate; more preferably, silica sol and / or white carbon black.

[0041] According to a preferred embodiment of the present invention, the alkali source is selected from alkaline metal salts, preferably at least one of sodium hydroxide, potassium hydroxide and calcium hydroxide; more preferably potassium hydroxide and / or sodium hydroxide.

[0042] According to a preferred embodiment of the present invention, the aluminum source is selected from at least one of pseudo-boehmite, aluminum sulfate, aluminum isopropoxide and sodium aluminate; more preferably aluminum sulfate and / or sodium aluminate.

[0043] According to a preferred embodiment of the present invention, the template is selected from at least one of ethylenediamine, tetramethylammonium hydroxide, 1,3-propylenediamine, 1,4-butylenediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-pentanediamine, hexamethylammonium bromide, hexamethylammonium chloride and hexamethylammonium hydroxide, further preferably at least one of hexamethylammonium hydroxide, 1,6-hexanediamine and hexamethylammonium chloride, and most preferably hexamethylammonium hydroxide.

[0044] According to a preferred embodiment of the present invention, the mass of the ZSM-48 molecular sieve seed added in step (1) is 0.01-10%, preferably 0.1-8%, more preferably 3-5% of the silicon source, and the silicon source is calculated as SiO2. Under the above preferred conditions, it is conducive to the formation of pure phase ZSM-48 molecular sieve.

[0045] According to a preferred embodiment of the present invention, the ZSM-48 molecular sieve seed crystals in step (1) are in the form of small spherical particles with a particle size between 300-700 nm.

[0046] According to the present invention, the crystallization reaction in step (2) mainly includes three crystallization processes at different temperatures, and the temperature of each crystallization process is higher than the temperature of the previous crystallization process. Preferably, the conditions of the crystallization reaction include: reacting at 20°C-50°C for 6-24h, reacting at 50°C-80°C for 12-36h, and then reacting at 80°C-180°C for 48-72h. Wherein, 20°C-50°C means 20°C≤t1<50°C, 50°C-80°C means 50°C≤t2≤80°C, and 80°C-180°C means 80°C<t3≤180°C. Under the above preferred embodiment, it is conducive to the formation of small-grained ZSM-48.

[0047] In the crystallization process of the present invention, continuous stirring or no stirring can be selected according to actual conditions. In the present invention, in order to ensure that the ZSM-48 molecular sieve of the present invention can be obtained better, it is preferred to continue stirring during the first stage of crystallization, and the intensity and speed of stirring are such that the reactants form a uniform colloid.

[0048] According to a preferred embodiment of the present invention, in step (3-2), the acidification deposition comprises: adding acid to the molecular sieve mother liquor to adjust the pH value to 3-7, preferably 5-6.5.

[0049] According to a preferred embodiment of the present invention, the acidification deposition time is 0.4-4h. The seed crystals and molecular sieve mother liquor obtained by the above preferred embodiment have the characteristic of promoting the formation of small crystals, and further recycling is conducive to the formation of uniform small crystal particles.

[0050] In the present invention, there is no specific limitation on the type of the acid described in step (3-2), as long as the above-mentioned pH adjustment effect can be achieved. Preferably, the acid can be at least one of hydrochloric acid, nitric acid, ammonium chloride and ammonium nitrate.

[0051] According to a preferred embodiment of the present invention, the source of the ZSM-48 molecular sieve seed crystals in step (1) includes at least one of the following three methods:

[0052] Mode 1: The method for preparing the ZSM-48 molecular sieve seed crystals comprises:

[0053] (1-1) providing a mixture containing a silicon source, an alkali source, an aluminum source, a template and water;

[0054] (1-2) subjecting the mixture to a crystallization reaction; the conditions of the crystallization reaction include: reacting at 20° C.-50° C. for 1-24 h, reacting at 50° C.-80° C. for 0.5-36 h, and then reacting at 80° C.-180° C. for 0.5-72 h;

[0055] (1-3) performing solid-liquid separation on the mixture obtained by the crystallization reaction in step (1-2) to obtain a molecular sieve mother liquor, and acidifying and precipitating the molecular sieve mother liquor to obtain ZSM-48 molecular sieve seed crystals;

[0056] Method 2: The ZSM-48 molecular sieve seed crystal is provided by the ZSM-48 molecular sieve obtained in step (3-1).

[0057] Method three: the ZSM-48 molecular sieve seed crystal is provided by the solid obtained by acidification deposition in step (3-2).

[0058] According to the present invention, in the preparation of ZSM-48 molecular sieve, it is necessary to first synthesize seed crystals, introduce the seed crystals into the reaction system to complete the initial crystallization reaction, and then go through step (3-1) and / or step (3-2) to realize the recycling of the crystallized product in the subsequent preparation process.

[0059] Among them, the selection range of the silicon source, alkali source, aluminum source and template agent in the first method can be the same as the above, and will not be repeated here; the types of the selected silicon source, alkali source, aluminum source and template agent can be the same as or different from the types of the silicon source, alkali source, aluminum source and template agent described in the above molecular sieve preparation process. Specifically, in the preparation process of the ZSM-48 molecular sieve seed, the content of each component in the reaction mixture satisfies the following relationship:

[0060] R / SiO2=0.01-0.50, more preferably 0.01-0.3;

[0061] H2O / SiO2=5-50, more preferably 5-20;

[0062] M + / SiO2=0.01-0.50, more preferably 0.01-0.15;

[0063] Al2O3 / SiO2=0-0.02; more preferably 0.01-0.017;

[0064] Wherein, R represents the template, M + It represents the alkali source, and SiO2 refers to the SiO2 in the silicon source.

[0065] According to a preferred embodiment of the present invention, the preparation method of the ZSM-48 molecular sieve seed mainly includes three steps of crystallization, and the temperature of each crystallization is higher than the previous crystallization temperature. Specifically, the first step crystallization temperature t1 satisfies 15°C≤t1<50°C, preferably at room temperature, more preferably 20°C≤t1≤45°C, and the first step crystallization time is 5-24h, preferably 6-15h; the second step crystallization temperature t2 satisfies 50°C≤t2<100°C, preferably 60°C≤t2≤80°C, and the second step crystallization time is 0.5-36h, preferably 5-30h; the third step crystallization temperature t3 satisfies 100°C≤t3≤200°C, preferably 120°C≤t3≤190°C, and the third step crystallization time is 10-96h, preferably 20-80h.

[0066] In the present invention, the acid deposition process in the preparation method of the ZSM-48 molecular sieve seed crystals can be the same as the acid deposition method in the aforementioned step (3-2), which will not be repeated here. The type of acid selected can be the same as or different from that in the aforementioned step.

[0067] According to a preferred embodiment of the present invention, the seed crystal preparation process further includes solid-liquid separation of the crystallization product to obtain the ZSM-48 molecular sieve seed crystal.

[0068] In order to obtain the molecular sieve raw powder of the present invention, the reaction system after the above crystallization can be further subjected to solid-liquid separation and drying and other operations. The methods and conditions for solid-liquid separation and drying are conventional operations in the art and are not repeated here. For example, the reaction product can be filtered and then dried at 120° C. for 6 hours to obtain the molecular sieve.

[0069] The third aspect of the present invention provides a hydroisomerization cracking catalyst, comprising a carrier and an active metal supported on the carrier, wherein the carrier comprises the ZSM-48 molecular sieve provided in the first aspect or the ZSM-48 molecular sieve prepared by the method described in the second aspect.

[0070] According to a preferred embodiment of the present invention, the active metal is selected from at least one of Pt, Pd, Ni and Co.

[0071] According to a preferred embodiment of the present invention, the active metal content is 0.1-2% by weight, preferably 0.2-1% by weight, calculated as the element, based on the total amount of the catalyst.

[0072] According to a preferred embodiment of the present invention, the content of the molecular sieve on a dry basis is 30-80% by weight, preferably 40-70% by weight, based on the total amount of the catalyst.

[0073] According to a preferred embodiment of the present invention, the hydroisomerization cracking catalyst further contains a binder. The type of the binder can be selected in a wide range, and preferably, the binder can be aluminum oxide and / or silicon oxide.

[0074] According to the present invention, the hydroisomerization cracking catalyst can be prepared by conventional methods in the prior art, as long as it contains the ZSM-48 molecular sieve described in the first aspect of the present invention or the ZSM-48 molecular sieve prepared by the method described in the second aspect, and meets the above-mentioned component requirements. The hydroisomerization cracking catalyst described in the present invention has excellent catalytic effect and has the characteristics of isomerization and intermediate rupture.

[0075] The fourth aspect of the present invention provides a method for hydroisomerization cracking of hydrocarbon oil, comprising: contacting a feedstock oil with a hydroisomerization cracking catalyst under hydroisomerization conditions, wherein the feedstock oil is a raw material for producing biojet fuel, and the hydroisomerization cracking catalyst is the hydroisomerization catalyst provided in the third aspect.

[0076] Preferably, the conditions for the hydroisomerization cracking include: a temperature of 200-500°C, preferably 250-400°C; a pressure of 1-30 MPa, preferably 2-20 MPa; a volume space velocity of 0.1-5 h -1 , preferably 0.1-3h -1 ; The volume ratio of hydrogen to oil is 50-3000, preferably 300-3000.

[0077] According to the hydrocarbon oil hydroisomerization cracking treatment method of the present invention, by using the hydroisomerization cracking catalyst provided by the present invention, the product obtained has a lower freezing point and a higher yield, and has a significant effect.

[0078] The present invention will be described in detail below through examples.

[0079] In the following examples and comparative examples, a Bruker D5005 diffractometer was used to perform XRD characterization on the samples, using 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 of 0.013°, and 1 step per second. A Hitachi S-4800 scanning electron microscope (SEM) was used to characterize the sample morphology and size, with an accelerating voltage of 20 kV.

[0080] The composition of the samples was determined using a 3271E X-ray fluorescence spectrometer (XRF) produced by Rigaku Corporation. The sample preparation method was the tablet pressing method, and the measurement conditions were an end-window rhodium target, a tube voltage of 50 kV, and a tube current of 50 mA.

[0081] The dry basis of molecular sieve and pseudo-boehmite in the examples refers to the weight after calcination at 600° C. for 2 h.

[0082] The pore structure parameters of the product, such as specific surface area and pore volume, were measured using the BET method.

[0083] The method for measuring element content in the product is DZ / T0279.1-2016.

[0084] Seed preparation example

[0085] (1) Sodium aluminate, 1,6-hexanediamine (HDA), sodium hydroxide and water were mixed in a certain proportion, stirred for 30 minutes and then silica sol was added. The molar ratio of each substance was n(Al2O3):(HDA):n(Na2O):n(H2O):n(SiO2)=0.01:0.20:0.30:30:1;

[0086] (2) The mixture was transferred into a crystallization kettle, stirred at room temperature for 6 hours, crystallized at 80°C for 24 hours, and crystallized at 180°C for 48 hours; after the crystallization, the molecular sieve mother liquor was filtered to obtain a certain amount of ammonium chloride, and a certain amount of ammonium chloride was added to the mother liquor until the pH value reached 6, at which time a precipitate was formed. After standing for 30 minutes, the precipitate was filtered to separate the acidified mother liquor. The obtained solid was washed with water and then dried at 120°C for 6 hours to obtain ZSM-48 molecular sieve seed crystals.

[0087] The following preparation example is used to illustrate the preparation of ZSM-48 molecular sieve.

[0088] Preparation Example 1

[0089] (1) Aluminum sulfate, hexamethyldiamine hydroxide (HMOH), potassium hydroxide, and molecular sieve mother liquor were mixed in a certain proportion, stirred for 30 minutes, and then silica sol was added. The molar ratio of each substance was n(Al2O3): (HMOH): n(Na + ): n(molecular sieve mother liquor): n(SiO2) = 0.02: 0.03: 0.3: 5: 1, add 10% of the mass of SiO2 in the silica sol, the seed is the ZSM-48 molecular sieve seed obtained in the seed preparation example;

[0090] (2) The mixture was transferred into a crystallization reactor, stirred at room temperature for 6 hours, crystallized at 80°C for 24 hours, and crystallized at 180°C for 48 hours; after the crystallization, it was filtered to obtain ZSM-48 molecular sieve and molecular sieve mother liquor. The ZSM-48 molecular sieve was washed with water and then dried at 120°C for 6 hours. The XRF analysis results of the silicon-aluminum ratio of the prepared ZSM-48 molecular sieve are shown in Table 1, the pore structure parameters are shown in Table 2, and the XRD diffraction peaks are shown in Table 3. Figure 1 , SEM images are shown in Figure 2 The particle length is less than 700 nm and the ratio of length to short diameter is about 1.2-1.5:1.

[0091] Preparation Example 2

[0092] (1) The molecular sieve mother liquor obtained in Preparation Example 1 was taken for standby use, and a certain amount of ammonium chloride was added to the mother liquor until the pH value reached 6.2, at which time a precipitate was formed. After standing for 1 hour, the precipitate was filtered to separate the acidified mother liquor.

[0093] (2) Aluminum sulfate, hexamethyldiamine chloride (HMCl), potassium hydroxide, and acidified mother liquor were mixed in a certain proportion, stirred for 30 minutes, and then silica sol was added. The molar ratio of each substance was n(Al2O3): (HMCl): n(Na + ):n(acidified mother liquor):n(SiO2)=0.001:0.03:0.3:30:1, add 10% of the mass of SiO2 in the silica sol to precipitate the solid in step (1).

[0094] (3) The mixture was transferred into a crystallization kettle, stirred at room temperature for 12 h, crystallized at 60 °C for 12 h, and crystallized at 170 °C for 48 h. After the crystallization, the mixture was filtered to obtain ZSM-48 molecular sieve and molecular sieve mother liquor. The ZSM-48 molecular sieve was washed with water and then dried at 120 °C for 6 h. The XRF analysis results of the silicon-aluminum ratio of the product are shown in Table 1, and the pore structure parameters are shown in Table 2. The particle length is 300-600 nm, and the length-to-short diameter ratio is about 1.1-1.4:1.

[0095] Preparation Example 3

[0096] (1) The molecular sieve mother liquor obtained in Preparation Example 2 was taken for standby use, and a certain amount of ammonium chloride was added to the mother liquor until the pH value was 5.8, at which time a precipitate was formed. After standing for 2 hours, the precipitate was filtered to separate the acidified mother liquor.

[0097] (2) Sodium aluminate, hexamethyldiamine chloride (HMCl), potassium hydroxide, and molecular sieve mother liquor were mixed in a certain proportion, stirred for 30 minutes, and then silica sol was added. The molar ratio of each substance was n(Al2O3): (HMCl): n(Na + ):n(acidified mother liquor):n(SiO2)=0.002:0.03:0.3:30:1, add 5% of the mass of SiO2 in the silica sol to precipitate the solid in step (1).

[0098] (3) The mixture was transferred into a crystallization kettle, stirred at room temperature for 24 h, crystallized at 80 °C for 36 h, and crystallized at 160 °C for 72 h. After the crystallization, the mixture was filtered to obtain ZSM-48 molecular sieve and molecular sieve mother liquor. The ZSM-48 molecular sieve was washed with water and then dried at 120 °C for 6 h. The XRF analysis results of the silicon-aluminum ratio of the product are shown in Table 1, and the pore structure parameters are shown in Table 2. The particle length is 300-700 nm, and the length-to-short diameter ratio is about 1.1-1.5:1.

[0099] Preparation Example 4

[0100] (1) The molecular sieve mother liquor obtained in Preparation Example 3 was taken for standby use, and a certain amount of ammonium chloride was added to the mother liquor until the pH value reached 3.8, at which time a precipitate was formed. After standing for 1 hour, the precipitate was filtered to separate the acidified mother liquor.

[0101] (2) Sodium aluminate, hexamethyldiamine chloride (HMCl), potassium hydroxide, and molecular sieve mother liquor were mixed in a certain proportion, stirred for 30 minutes, and then silica sol was added. The molar ratio of each substance was n(Al2O3): (HMCl): n(Na + ):n(acidified mother liquor):n(SiO2)=0.0125:0.03:0.3:30:1, add 5% of the mass of SiO2 in the silica sol to precipitate the solid in step (1).

[0102] (3) The mixture was transferred into a crystallization kettle, stirred at room temperature for 6 hours, crystallized at 80°C for 24 hours, and crystallized at 180°C for 48 hours. After the crystallization, the mixture was filtered to obtain ZSM-48 molecular sieve and molecular sieve mother liquor. The ZSM-48 molecular sieve was washed with water and then dried at 120°C for 6 hours. The XRF analysis results of the silicon-aluminum ratio of the product are shown in Table 1, and the pore structure parameters are shown in Table 2. The particle length is 400-700nm, and the length-to-short diameter ratio is about 1.2-1.4:1.

[0103] Preparation Example 5

[0104] (1) The molecular sieve mother liquor obtained in Preparation Example 4 was taken for standby use, and a certain amount of ammonium chloride was added to the mother liquor until the pH value reached 6.2, at which time a precipitate was formed. After standing for 0.5 h, the precipitate was filtered to separate the acidified mother liquor.

[0105] (2) Sodium aluminate, hexamethyldiamine chloride (HMCl), potassium hydroxide, and molecular sieve mother liquor were mixed in a certain proportion, stirred for 30 minutes, and then silica sol was added. The molar ratio of each substance was n(Al2O3): (HMCl): n(Na + ):n(acidified mother liquor):n(SiO2)=0.004:0.01:0.3:30:1, add 10% of the mass of SiO2 in the silica sol to precipitate the solid in step (1).

[0106] (3) The mixture was transferred into a crystallization kettle, stirred at 40°C for 6 hours, crystallized at 70°C for 24 hours, and crystallized at 180°C for 48 hours. After the crystallization, the mixture was filtered to obtain ZSM-48 molecular sieve and molecular sieve mother liquor. The ZSM-48 molecular sieve was washed with water and then dried at 120°C for 6 hours. The XRF analysis results of the silicon-aluminum ratio of the product are shown in Table 1, and the pore structure parameters are shown in Table 2. The particle length is 300-600nm, and the length-to-short diameter ratio is about 1.1-1.5:1.

[0107] Preparation Example 6

[0108] (1) Sodium aluminate, hexamethyldiamine chloride (HMCl), sodium hydroxide, and molecular sieve mother liquor were mixed in a certain proportion, stirred for 30 minutes, and then white carbon black was added. The molar ratio of each substance was n(Al2O3): (HMCl): n(Na + ): n(molecular sieve mother liquor): n(SiO2) = 0.01:0.01:0.1:30:1, add 10% of the mass of SiO2 seed crystals, the seed crystals are the ZSM-48 molecular sieve seed crystals obtained in the seed preparation example.

[0109] (2) The mixture was transferred into a crystallization kettle, stirred at 50°C for 6 hours, crystallized at 70°C for 24 hours, and crystallized at 160°C for 72 hours. After the crystallization, the mixture was filtered and filtered to obtain ZSM-48 molecular sieve and molecular sieve mother liquor. The ZSM-48 molecular sieve was washed with water and then dried at 120°C for 6 hours. The XRF analysis results of the silicon-aluminum ratio of the product are shown in Table 1, and the pore structure parameters are shown in Table 2. The particle length is 400-600nm, and the length-to-short diameter ratio is about 1.1-1.4:1.

[0110] Comparative Preparation Example 1

[0111] Sodium aluminate, hexamethylenediamine, sodium hydroxide and deionized water were mixed in a certain proportion, stirred for 30 minutes and then silica sol was added. The molar ratio of each substance was n(Al2O3): (HDA): n(Na + ):n(H2O):n(SiO2)=0.0125:0.012:0.2:26:1, the mixture was transferred into a crystallization kettle, stirred at 50℃ for 6h, crystallized at 70℃ for 24h, and crystallized at 160℃ for 72h. The pore structure parameters of the product are shown in Table 2.

[0112] Comparative Preparation Example 2

[0113] Sodium aluminate, tetramethylammonium hydroxide, potassium hydroxide and deionized water were mixed in a certain proportion, stirred for 30 minutes and then silica sol was added. The molar ratio of each substance was n(Al2O3):(TMAOH):n(K + ): n(H2O): n(SiO2) = 0.004: 0.01: 0.3: 28: 1, the mixture was transferred into a crystallization reactor and crystallized at 160°C for 72 hours. The pore structure parameters of the product are shown in Table 2, and the morphology is shown in Figure 3 shown.

[0114] The following examples are used to illustrate the preparation of hydroisomerization cracking catalysts.

[0115] Examples 1-6 and Comparative Examples 1-2

[0116] 100 g of the molecular sieves in Preparation Example 1-6 and Comparative Preparation Example 1-2 were respectively mixed with 100 g of alumina, extruded, dried, and calcined to obtain a carrier. The mass fraction of the molecular sieve in the carrier was measured to be 51%.

[0117] Pour 1 gram of dichlorotetraamineplatinum (containing 57.3% Pt by mass) into 100 grams of deionized water and stir until uniform. Pour 100 grams of the carrier into the above solution and soak at room temperature for 4 hours. Subsequently, the above catalyst precursor is dried at 120°C for 4 hours. Then, it is calcined under the state of passing air flow, the calcination temperature is 450°C, and the time is 4 hours. The semi-finished catalyst is placed in a hydrogen atmosphere again and reduced at 400°C for 4 hours to obtain a catalyst. Examples 1-6 and Comparative Examples 1-2 are named IC-1 to IC-8, respectively.

[0118] IC-1 to IC-8 were evaluated using the following evaluation method:

[0119] 50g of catalyst was loaded into a high-pressure hydrogenation reactor. The bio-jet fuel raw material was injected into the reactor from top to bottom for reaction. The reaction conditions were shown in Table 3 below, and the analysis data of the bio-jet fuel raw material was shown in Table 4. After the reaction, the product was distilled to remove light components with a temperature less than 160 degrees, and the components with a temperature greater than 160 degrees were analyzed and the yield was calculated. The results are shown in Table 5.

[0120] Table 1

[0121] sample Silicon-aluminum ratio XRF analysis results Preparation Example 1 49.8 Preparation Example 2 989 Preparation Example 3 476 Preparation Example 4 79 Preparation Example 5 236 Preparation Example 6 98 Comparative Preparation Example 1 82 Comparative Preparation Example 2 256

[0122] Table 2

[0123]

[0124]

[0125] Table 3 Catalyst evaluation conditions

[0126] Reaction conditions condition Pressure, MPa 6.8 <![CDATA[Air speed, h -1 > 1.0 Reaction temperature, °C 340 Hydrogen to oil ratio, v / v 400

[0127] Table 4 Analysis results of bio-jet fuel raw materials

[0128] Analyze Project Analyze the data Analytical methods <![CDATA[Density at 20 °C / (kg / m 3 )]]> 778.2 SH / T0604-2000 Freezing point / ℃ +16 SH / T 0771-2005 Nitrogen mass fraction / (μg / g) 1.2 NB / SH / T 0704-2010 Sulfur mass fraction / (μg / g) 2.1 SH / T 0842-2010 Distillation range / ℃ ASTM D-1160 IBP 270 10％ 279 50％ 289 95％ 306 FBP 320

[0129] Table 5 Evaluation results

[0130] Freezing point / ℃ Yield / % Example 1 -48 76 Example 2 -48 75 Example 3 -48 76 Example 4 -47 75 Example 5 -48 76 Example 6 -48 77 Comparative Example 1 -43 62 Comparative Example 2 -43 66

[0131] It can be seen from the results of the above examples that the ZSM-48 molecular sieve prepared by the present invention has an ellipsoidal morphology and a small specific surface area. When the molecular sieve prepared is further applied to the production of bio-jet fuel, the product yield is higher and the freezing point is lower.

[0132] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A ZSM-48 molecular sieve, wherein the molar ratio of silicon oxide to aluminum oxide in the ZSM-48 molecular sieve is not less than 40, and the specific surface area of ​​the ZSM-48 molecular sieve is 150-200m 2 / g, the ZSM-48 molecular sieve is ellipsoidal, the major diameter does not exceed 700nm and the ratio of major diameter to minor diameter is 1-3:1; The pore volume of the ZSM-48 molecular sieve is 0.15-0.20 ml / g; The ZSM-48 molecular sieve is prepared by the following preparation method, including: (1) providing a mixture containing a silicon source, an alkali source, an aluminum source, a template, a molecular sieve mother liquor, and a ZSM-48 molecular sieve seed crystal; (2) subjecting the mixture to a crystallization reaction; the conditions of the crystallization reaction include: reacting at 20°C-50°C for 1-24 hours, reacting at 50°C-80°C for 0.5-36 hours, and then reacting at 80°C-180°C for 0.5-72 hours; (3-1) The mixture obtained by the crystallization reaction in step (2) is subjected to solid-liquid separation to obtain ZSM-48 molecular sieve and molecular sieve mother liquor, and the molecular sieve mother liquor is returned to step (1); and / or (3-2) The mixture obtained from the crystallization reaction in step (2) is subjected to solid-liquid separation to obtain a product and a molecular sieve mother liquor. The molecular sieve mother liquor is subjected to acidification and precipitation, and then subjected to solid-liquid separation. The obtained acidified mother liquor is returned to step (1).

2. A method for preparing a ZSM-48 molecular sieve, the method comprising the following steps: (1) providing a mixture containing a silicon source, an alkali source, an aluminum source, a template, a molecular sieve mother liquor, and a ZSM-48 molecular sieve seed crystal; (2) subjecting the mixture to a crystallization reaction; the conditions of the crystallization reaction include: reacting at 20°C-50°C for 1-24 hours, reacting at 50°C-80°C for 0.5-36 hours, and then reacting at 80°C-180°C for 0.5-72 hours; (3-1) The mixture obtained by the crystallization reaction in step (2) is subjected to solid-liquid separation to obtain ZSM-48 molecular sieve and molecular sieve mother liquor, and the molecular sieve mother liquor is returned to step (1); and / or (3-2) The mixture obtained from the crystallization reaction in step (2) is subjected to solid-liquid separation to obtain a product and a molecular sieve mother liquor. The molecular sieve mother liquor is subjected to acidification and precipitation, and then subjected to solid-liquid separation. The obtained acidified mother liquor is returned to step (1).

3. The preparation method according to claim 2, wherein The composition of each component in the mixture in step (1) calculated by molar amount satisfies the following relationship: R / SiO2 = 0.01-0.50; Molecular sieve mother liquor / SiO2=5-50; M + / SiO2=0.01-0.50; Al2O3 / SiO2=0-0.03; where SiO2 refers to SiO2 in the silicon source, R represents the template, and M + It represents the alkali source. The molar amount of the molecular sieve mother liquor is calculated based on pure water, which is the mass of the molecular sieve mother liquor / 18.

4. The preparation method according to claim 3, wherein The composition of each component in the mixture in step (1) calculated by molar amount satisfies the following relationship: R / SiO2 = 0.01-0.1; Molecular sieve mother liquor / SiO2=5-30; M + / SiO2= 0.1-0.3; Al2O3 / SiO2= 0.001-0.025; where SiO2 refers to SiO2 in the silicon source, R represents the template, and M + It represents the alkali source. The molar amount of the molecular sieve mother liquor is calculated based on pure water, which is the mass of the molecular sieve mother liquor / 18.

5. The preparation method according to claim 3 or 4, wherein The method step (1) does not involve the additional addition of water.

6. The preparation method according to claim 2, wherein: The silicon source is selected from at least one of silica sol, white carbon black, fumed silica, water glass and tetraethyl orthosilicate.

7. The preparation method according to claim 2, wherein: The alkalinity source is selected from alkaline metal salts.

8. The preparation method according to claim 7, wherein: The alkali source is selected from at least one of sodium hydroxide, potassium hydroxide and calcium hydroxide.

9. The preparation method according to claim 2, wherein: The aluminum source is selected from at least one of pseudo-boehmite, aluminum sulfate, aluminum isopropoxide and sodium aluminate.

10. The preparation method according to claim 2, wherein: The template agent is selected from at least one of ethylenediamine, tetramethylammonium hydroxide, 1,3-propylenediamine, 1,4-butylenediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-hexanediamine, hexamethylammonium bromide, hexamethylammonium chloride and hexamethylammonium hydroxide.

11. The preparation method according to any one of claims 2 to 10, wherein: The mass of the ZSM-48 molecular sieve seed added in step (1) is 0.01-10% of the silicon source.

12. The preparation method according to claim 11, wherein The mass of the ZSM-48 molecular sieve seed added in step (1) is 0.1-8% of the silicon source, where the silicon source is calculated as SiO2.

13. The preparation method according to claim 12, wherein: The mass of the ZSM-48 molecular sieve seed added in step (1) is 3-5% of the silicon source, where the silicon source is calculated as SiO2.

14. The preparation method according to any one of claims 2 to 10, wherein: The ZSM-48 molecular sieve seed crystals in step (1) are ellipsoidal in shape, with a major diameter of 300-700 nm.

15. The preparation method according to any one of claims 2 to 10, wherein: The conditions of the crystallization reaction include: reacting at 20°C-50°C for 6-24h, reacting at 50°C-80°C for 12-36h, and then reacting at 80°C-180°C for 48-72h.

16. The preparation method according to any one of claims 2 to 10, wherein: In step (3-2), the acidification deposition comprises: adding acid to the molecular sieve mother liquor and adjusting the pH value to 3-7.

17. The preparation method according to claim 16, wherein: In step (3-2), the acidification deposition comprises: adding acid to the molecular sieve mother liquor and adjusting the pH value to 5-6.

5.

18. The preparation method according to claim 16, wherein: The acidification deposition time is 0.5h-4h.

19. The preparation method according to any one of claims 2 to 10, wherein: The source of the ZSM-48 molecular sieve seed crystals includes at least one of the following three methods; Mode 1: The method for preparing the ZSM-48 molecular sieve seed crystals comprises: (1-1) Providing a mixture containing a silicon source, an alkali source, an aluminum source, a template and water; (1-2) subjecting the mixture to a crystallization reaction; the conditions of the crystallization reaction include: reacting at 20°C-50°C for 1-24 hours, reacting at 50°C-80°C for 0.5-36 hours, and then reacting at 80°C-180°C for 0.5-72 hours; (1-3) performing solid-liquid separation on the mixture obtained by the crystallization reaction in step (1-2) to obtain a molecular sieve mother liquor, and acidifying and precipitating the molecular sieve mother liquor to obtain ZSM-48 molecular sieve seed crystals; Method 2: The ZSM-48 molecular sieve seed crystal is provided by the ZSM-48 molecular sieve obtained in step (3-1); Method three: The ZSM-48 molecular sieve seed crystal is provided by the solid obtained by acidification deposition in step (3-2).

20. A hydroisomerization cracking catalyst comprising a carrier and an active metal supported on the carrier, wherein the carrier comprises the ZSM-48 molecular sieve according to claim 1 or the ZSM-48 molecular sieve prepared by the method according to any one of claims 2 to 19.

21. The catalyst according to claim 20, wherein The active metal is selected from at least one of Pt, Pd, Ni and Co.

22. The catalyst according to claim 21, wherein The active metal content is 0.1-2% by weight as an element, based on the total amount of the catalyst.

23. The catalyst according to claim 22, wherein The active metal content is 0.2-1% by weight as an element, based on the total amount of the catalyst.

24. The catalyst according to claim 20, wherein Based on the total amount of the catalyst, the content of the molecular sieve on a dry basis is 30-80% by weight.

25. The catalyst according to claim 24, wherein Based on the total amount of the catalyst, the content of the molecular sieve on a dry basis is 40-70% by weight.

26. A hydrocarbon oil hydroisomerization cracking method comprising: Under hydroisomerization conditions, the feedstock oil is contacted with a hydroisomerization cracking catalyst, wherein the feedstock oil is a raw material for producing biojet fuel, and the hydroisomerization cracking catalyst is the hydroisomerization cracking catalyst as described in any one of claims 20-25.

27. The method according to claim 26, wherein: The conditions of the hydroisomerization include: temperature of 200-500°C; pressure of 1-30MPa; volume space velocity of 0.1-5h -1 ; The volume ratio of hydrogen to oil is 50-3000.

28. The method according to claim 27, wherein: The conditions of the hydroisomerization include: temperature of 250-400°C; pressure of 2-20 MPa; volume space velocity of 0.1-3 h -1 ; The volume ratio of hydrogen to oil is 300-3000.

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