Chain alkane isomerization catalyst as well as preparation method and application thereof

Abstract

The invention discloses a chain alkane isomerization catalyst as well as a preparation method and application thereof. The chain alkane isomerization catalyst comprises a hydrogen type ZSM-48 molecular sieve, an active component and a binder, the hydrogen type ZSM-48 molecular sieve has a spherical crystal structure or an ellipsoidal crystal structure; the hydrogen type ZSM-48 molecular sieve is provided with micropores and mesopores; the active component is loaded on the hydrogen type ZSM-48 molecular sieve; the active component comprises an active element, and the active element is selected from at least one of nickel, cobalt, platinum and palladium; the binder is selected from at least one of aluminum oxide, silicon oxide and clay. The chain alkane isomerization catalyst prepared by the method has the characteristics of high activity and high isomer yield.

Description

Technical Field

[0001] The present application relates to a chain alkane isomerization catalyst, a preparation method thereof and an application thereof, belonging to the technical field of catalytic chemistry. Background Art

[0002] The isomerization of long-chain alkanes is a key process for producing high-octane gasoline and improving the low-temperature performance and viscosity index of diesel and lubricating oil. This reaction usually occurs on a bifunctional catalyst, which includes a metal and an acidic support. The dehydrogenation / hydrogenation reaction occurs at the metal site, and the skeletal isomerization reaction occurs at the acidic site. A large number of studies have shown that one-dimensional mesoporous molecular sieves (ZSM-22 (TON), SAPO-11 (AEL), ZSM-23 (MTT), ZSM-48 (*MRE), etc.) are the most suitable acidic supports, and their unique one-dimensional pore structure exhibits higher isomer yields and better cracking inhibition ability (Zhang M, Li C, Chen X, et al. Industrial & Engineering Chemistry Research, 2016, 55, 6069-6078.). Among them, the reaction products of the ZSM-48 molecular sieve-based catalyst contain a higher proportion of intermediate branched-chain isomer components, which makes the product have better low-temperature performance. And theoretical calculations show that during the isomerization of long-chain alkanes, the ZSM-48 molecular sieve has relatively excellent n-alkane adsorption and activation ability. Therefore, the ZSM-48 molecular sieve is regarded as one of the most promising acidic supports.

[0003] The balance and coordination of the acid center and the metal center in the bifunctional catalyst are the key to constructing an excellent long-chain alkane isomerization catalyst, which is mainly reflected in the concentration ratio and the distance effect. The relatively low and difficult-to-adjust acid density of the ZSM-48 molecular sieve makes it difficult to fully exert the advantages of the pore structure, which is the main obstacle hindering its industrial application. In addition, the traditional rod-like morphology of the ZSM-48 molecular sieve results in a large number of non-selective acid sites on the outer surface of the catalyst, which also weakens the selectivity of the catalyst. To solve these problems, many solutions have been proposed by researchers. For example, the use of a special template agent to synthesize aluminum-rich ZSM-48 molecular sieve to make up for the lack of acidity (CN110127719A); adopting a post-treatment or in-situ synthesis strategy to construct a hierarchical pore ZSM-48 molecular sieve to enhance the diffusion performance of the catalyst (Zhang M, Li C, Chen X, et al. Industrial & Engineering Chemistry Research, 2019, 58: 19855-19861.). How to synchronously regulate the acid density, diffusion performance and morphology of the ZSM-48 molecular sieve to construct an excellent long-chain alkane hydroisomerization catalyst is still a topic worthy of exploration. Summary of the Invention

[0004] The object of the present application is to develop a catalytic material for the isomerization of linear alkanes. The long-chain alkane isomerization catalyst obtained by this method has the characteristics of high selectivity, good catalytic activity and stability.

[0005] In one aspect of the present application, a linear alkane isomerization catalyst is provided, and the linear alkane isomerization catalyst includes a hydrogen-form ZSM-48 molecular sieve, an active component and a binder;

[0006] The hydrogen-form ZSM-48 molecular sieve has a spherical crystal structure or an ellipsoidal crystal structure;

[0007] The hydrogen-form ZSM-48 molecular sieve has micropores and mesopores;

[0008] The active component is loaded on the hydrogen-form ZSM-48 molecular sieve;

[0009] The active component includes an active element, and the active element is selected from at least one of nickel, cobalt, platinum, and palladium;

[0010] The binder is selected from at least one of alumina, silica, and clay.

[0011] Optionally, the mass content of the hydrogen-form ZSM-48 molecular sieve in the linear alkane isomerization catalyst is 40-90 wt%.

[0012] Optionally, the mass content of the hydrogen-form ZSM-48 molecular sieve in the linear alkane isomerization catalyst is independently selected from any value of 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, 85 wt%, 90 wt% or any range value between any two of the above.

[0013] Optionally, the mass content of the active component in the linear alkane isomerization catalyst is 0.05-10 wt%, and the mass of the active component is calculated based on the mass of the active element.

[0014] Optionally, the mass content of the active component in the linear alkane isomerization catalyst is independently selected from any value of 0.05 wt%, 0.1 wt%, 0.5 wt%, 1 wt%, 3.5 wt%, 5 wt%, 8 wt%, 10 wt% or any range value between any two of the above.

[0015] Optionally, the mass content of the binder in the linear alkane isomerization catalyst is 3-15 wt%.

[0016] Optionally, the mass content of the binder in the linear paraffin isomerization catalyst is independently selected from any value among 3 wt%, 5 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt% or any range value between any two of the above.

[0017] Optionally, the silica-alumina ratio of the hydrogen-form ZSM-48 molecular sieve is 30 to 400.

[0018] Optionally, the silica-alumina ratio of the hydrogen-form ZSM-48 molecular sieve is independently selected from any value among 30, 50, 100, 150, 200, 250, 300, 350, 400 or any range value between any two of the above.

[0019] Optionally, in the hydrogen-form ZSM-48 molecular sieve, the micropore volume is 0.04 to 0.09 cm 3 / g, and the mesopore volume is 0.2 to 0.8 cm 3 / g.

[0020] As a specific embodiment, the linear paraffin isomerization catalyst has a spherical or ellipsoidal hierarchical pore hydrogen-form ZSM-48 molecular sieve, a metal species and a binder, wherein the metal species is selected from at least one of nickel nitrate, nickel chloride, cobalt nitrate, cobalt chloride, chloroplatinic acid, ammonium chloroplatinate, platinum chloride, palladium chloride.

[0021] Another aspect of the present application provides a preparation method of the above linear paraffin isomerization catalyst, which solves the above technical problems by using appropriate raw materials and finely adjusting the composition of the raw materials, and adopting the hydrothermal crystallization method and the incipient wetness impregnation method.

[0022] The preparation method includes:

[0023] (1) After mixing the ZSM-48 molecular sieve precursor with the mother liquor, aging I, hydrothermal crystallization I, calcination I, and ion exchange are carried out to obtain the hydrogen-form ZSM-48 molecular sieve;

[0024] Wherein, the mother liquor includes aluminum source I, template agent I, inorganic base I and water I;

[0025] (2) The hydrogen-form ZSM-48 molecular sieve and the binder are extruded into shape and then calcined II. A carrier is obtained;

[0026] (3) An aqueous solution containing an active element precursor is mixed with the carrier, incipient wetness impregnation is carried out, and calcination III is carried out to obtain the linear paraffin isomerization catalyst.

[0027] As a specific embodiment, the preparation method of the linear paraffin isomerization catalyst includes:

[0028] S1. After mixing the ZSM-48 molecular sieve parent with the mother liquor, aging and hydrothermal crystallization are carried out to obtain spherical or ellipsoidal hierarchical pore ZSM-48 molecular sieve raw powder, and then the spherical or ellipsoidal hierarchical pore hydrogen form ZSM-48 molecular sieve is obtained through calcination and ion exchange.

[0029] The mother liquor includes an aluminum source, a template agent, an inorganic base, and water.

[0030] S2. Then, the spherical or ellipsoidal hierarchical pore hydrogen form ZSM-48 molecular sieve and a binder are extruded into a catalyst carrier.

[0031] S3. The metal species are in the form of an aqueous solution, and the metal and the carrier are compounded by the equal-volume impregnation method, and then the chain alkane isomerization catalyst is obtained through calcination in an air atmosphere.

[0032] Optionally, in step (1), the microstructure of the ZSM-48 molecular sieve parent is spherical or ellipsoidal.

[0033] Optionally, the particle size of the ZSM-48 molecular sieve parent is 400 - 4000 nm.

[0034] Optionally, the particle size of the ZSM-48 molecular sieve parent is 500 - 3000 nm.

[0035] Optionally, the surface of the ZSM-48 molecular sieve parent has micropores and mesopores, the pore volume of the micropores is 0.03 - 0.09 cm 3 / g, and the total pore volume is 0.02 - 0.25 cm 3 / g.

[0036] Optionally, the silica-alumina ratio of the ZSM-48 molecular sieve parent is ≥120.

[0037] Optionally, in step (1), the ion exchange procedure is as follows: adding the molecular sieve raw powder into a 1 mol / L NH4Cl solution, with a liquid-solid mass ratio of 6 - 30, stirring at 80 °C for 1 h. Repeat the exchange 3 times, filter, and wash to obtain the ammonium form molecular sieve. The ammonium form molecular sieve is calcined in an air atmosphere at 550 °C for 4 h to obtain the hydrogen form molecular sieve catalyst.

[0038] Optionally, the preparation method of the ZSM-48 molecular sieve parent includes:

[0039] An aqueous solution containing a silicon source II, an inorganic base II, and a template agent II is aged II and hydrothermally crystallized II to obtain the ZSM-48 molecular sieve parent.

[0040] As a specific implementation manner, the preparation method of the ZSM-48 molecular sieve parent at least includes the following steps:

[0041] After mixing the raw materials containing silicon source I, inorganic base I, and template agent I with water, aging I, hydrothermal crystallization I, washing, drying, and calcination are carried out to obtain the ZSM-48 molecular sieve precursor.

[0042] Optionally, the silicon source II is selected from at least one of fumed silica, silica sol, tetraethyl orthosilicate, and water glass.

[0043] Optionally, the inorganic base II is selected from at least one of sodium hydroxide, sodium carbonate, potassium hydroxide, lithium hydroxide, and ammonia water;

[0044] The molar ratio of the inorganic base II to the silicon source II is 0.2 to 0.6, wherein the molar amount of the silicon source II is calculated based on the molar amount of SiO2 in the silicon source II, and the molar amount of the inorganic base II is calculated based on the hydroxide in the inorganic base II.

[0045] Optionally, the molar ratio of the inorganic base II to the silicon source II independently selects any value from 0.2, 0.25, 0.35, 0.45, 0.55, 0.6 or any range value between any two of the above.

[0046] Optionally, the concentration of the ammonia water is 25 wt%.

[0047] Optionally, the template agent II is selected from at least one of hexamethylammonium bromide, hexamethylammonium chloride, and hexamethylammonium hydroxide;

[0048] The molar ratio of the template agent II to the silicon source II is 0.02 to 0.3, wherein the molar amount of the template agent II is calculated based on the molar amount of hexamethylammonium in the template agent II, and the molar amount of the silicon source II is calculated based on the molar amount of SiO2 in the silicon source II.

[0049] Optionally, the molar ratio of the template agent II to the silicon source II independently selects any value from 0.02, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3 or any range value between any two of the above.

[0050] Optionally, the molar ratio of water to the silicon source II in the aqueous solution is 25 to 60, wherein the molar amount of the silicon source II is calculated based on the molar amount of SiO2 in the silicon source II.

[0051] Optionally, the molar ratio of water to the silicon source II in the aqueous solution independently selects any value from 25, 35, 45, 55, 60 or any range value between any two of the above.

[0052] Optionally, the aqueous solution further contains an aluminum source II; the aluminum source II is selected from at least one of aluminum nitrate, aluminum sulfate, sodium aluminate, pseudo-boehmite, and aluminum chloride.

[0053] Optionally, the molar ratio of the silicon source II to the aluminum source II is ≥120, where the molar amount of the aluminum source II is calculated based on the molar amount of Al2O3 in the aluminum source II;

[0054] The conditions for the second aging are: temperature 25 - 80 °C, time 2 - 8 h.

[0055] Optionally, the conditions for the second hydrothermal crystallization are: dynamic crystallization, temperature 110 - 200 °C, time 48 - 120 h.

[0056] The second dynamic crystallization is carried out in a autoclave reactor in a rotary oven, and the rotation speed of the rotary oven is 10 - 80 r / min.

[0057] After the crystallization is completed, through filtration, washing, and calcination at 500 °C for 6 h to remove the template agent, the molecular sieve matrix is obtained.

[0058] Optionally, the mass ratio of the mother liquor to the ZSM-48 molecular sieve matrix is 5 - 70.

[0059] Optionally, the mass ratio of the mother liquor to the ZSM-48 molecular sieve matrix independently selects any value from 5, 10, 20, 25, 30, 35, 45, 55, 65, 70 or any range value between any two of the above.

[0060] Optionally, the aluminum source I is selected from at least one of aluminum nitrate, aluminum sulfate, sodium aluminate, pseudo-boehmite, or aluminum chloride;

[0061] In the mother liquor, the concentration of the aluminum source I is 0.001 - 0.1 mol / L, where the concentration of the aluminum source I is calculated based on the concentration of Al ions.

[0062] Optionally, the concentration of the aluminum source I independently selects any value from 0.001 mol / L, 0.005 mol / L, 0.01 mol / L, 0.03 mol / L, 0.4 mol / L, 0.055 mol / L, 0.07 mol / L, 0.085 mol / L, 0.1 mol / L or any range value between any two of the above.

[0063] Optionally, the inorganic base I is selected from at least one of sodium hydroxide, potassium hydroxide, or lithium hydroxide;

[0064] In the mother liquor, the concentration of the inorganic base I is 0.1 - 0.8 mol / L, where the concentration of the inorganic base I is calculated based on the concentration of OH - in terms of concentration.

[0065] Optionally, the concentration of the inorganic base I is independently selected from any value among 0.1 mol / L, 0.15 mol / L, 0.25 mol / L, 0.35 mol / L, 0.45 mol / L, 0.55 mol / L, 0.65 mol / L, 0.75 mol / L, 0.8 mol / L or any range value between any two of the above.

[0066] Optionally, the template agent I is selected from at least one of hexamethonium bromide, hexamethonium chloride or hexamethonium hydroxide;

[0067] In the mother liquor, the concentration of the template agent I is 0.06 - 0.45 mol / L, wherein the concentration of the template agent I is calculated based on the concentration of hexamethonium.

[0068] Optionally, the concentration of the template agent I is independently selected from any value among 0.06 mol / L, 0.08 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.4 mol / L, 0.45 mol / L or any range value between any two of the above.

[0069] Optionally, the conditions for aging I are: the temperature is 30 - 80 °C and the time is 2 - 8 h.

[0070] Optionally, the temperature of aging I is independently selected from any value among 30 °C, 40 °C, 50 °C, 60 °C, 70 °C, 80 °C or any range value between any two of the above.

[0071] Optionally, the time of aging I is independently selected from any value among 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h or any range value between any two of the above.

[0072] Optionally, the conditions for hydrothermal crystallization I are: the temperature is 120 - 200 °C and the time is 48 - 120 h.

[0073] Optionally, the hydrothermal crystallization I is dynamic crystallization under autogenous pressure.

[0074] Optionally, the dynamic crystallization means it is carried out in a kettle reactor in a rotary oven;

[0075] The rotation speed of the rotary oven is 10 - 80 r / min.

[0076] Optionally, the conditions for calcination I are: the temperature is 400 - 600 °C and the time is 1 - 8 h.

[0077] Optionally, the conditions for calcination II are: the temperature is 300 - 500 °C and the time is 0.5 - 6 h.

[0078] As a specific embodiment, the spherical or ellipsoidal hierarchical pore hydrogen form ZSM-48 molecular sieve is mixed with a binder, and a catalyst support is obtained by extrusion molding and calcination at 500 °C for 3 h.

[0079] Optionally, the active element precursor is selected from at least one of nickel nitrate, nickel chloride, cobalt nitrate, cobalt chloride, chloroplatinic acid, ammonium chloroplatinate, platinum chloride, and palladium chloride.

[0080] Optionally, the conditions for Calcination III are as follows: carried out in an air atmosphere, the temperature is 300-450 °C, and the time is 1-3 h.

[0081] As a specific embodiment, the metal precursor is in the form of an aqueous solution and is compounded with the support by the equal-volume impregnation method. After drying at room temperature, it is calcined in an air atmosphere to obtain the chain alkane isomerization catalyst.

[0082] In another aspect of the present application, a method for chain alkane isomerization is provided, which is the application of the above-mentioned chain alkane isomerization catalyst or the chain alkane isomerization catalyst prepared by the above-mentioned preparation method, and is used as a catalyst for catalyzing the chain alkane isomerization reaction.

[0083] Optionally, the method includes:

[0084] Under the condition of Hydrogen I, a raw material containing a chain alkane is contacted with the pretreated chain alkane isomerization catalyst and reacts;

[0085] Among them, the chain alkane is selected from at least one of normal chain alkanes with C6-C 18 ;

[0086] The chain alkane isomerization catalyst is selected from the above-mentioned chain alkane isomerization catalysts.

[0087] As a specific embodiment, the catalyst precursor is reduced and activated in an H2 atmosphere. After activation, the temperature is lowered to the reaction temperature, and then a raw material containing a chain alkane is contacted with the chain alkane isomerization catalyst and reacts.

[0088] Optionally, the pretreatment includes: the chain alkane isomerization catalyst is reduced and activated in a Hydrogen II atmosphere;

[0089] The temperature of the reduction activation is 400-550 °C, and the time of the reduction activation is 1-5 h.

[0090] Optionally, the temperature of the reaction is 200-370 °C.

[0091] The pressure of the reaction is 0-4 MPa;

[0092] The mass hourly space velocity of the hydrogen I is 0.5 to 10 h -1 ;

[0093] In the reaction, the volume ratio of the hydrogen I to the linear alkane is 50 to 400.

[0094] Optionally, the temperature of the reaction is independently selected from any value among 200 °C, 240 °C, 280 °C, 320 °C, 340 °C, 370 °C or the range values between any two of the above.

[0095] Optionally, the pressure of the reaction is independently selected from any value among 0 MPa, 0.5 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3.5 MPa, 4 MPa or the range values between any two of the above.

[0096] Optionally, the mass hourly space velocity of the hydrogen I is independently selected from any value among 0.5 h -1 , 0.8 h -1 , 1.2 h -1 , 2.4 h -1 , 3.6 h -1 , 4.8 h -1 , 6 h -1 , 7.2 h -1 , 8.4 h -1 , 10 h -1 or the range values between any two of the above.

[0097] Optionally, the volume ratio of the hydrogen I to the linear alkane is independently selected from any value among 50, 80, 120, 160, 180, 220, 260, 280, 320, 360, 400 or the range values between any two of the above.

[0098] The beneficial effects that can be produced by this application include:

[0099] (1) This application provides a multi - pore hydrogen - type ZSM - 48 molecular sieve with a spherical or ellipsoidal structure as an acidic carrier for the isomerization catalyst of linear alkanes. It has the advantages of adjustable silicon - aluminum ratio, good diffusion performance, and the highly condensed spherical agglomeration morphology reduces the external surface acid sites, and can effectively improve the catalytic selectivity.

[0100] (2) The linear alkane isomerization catalyst described in this application has good catalytic activity and isoparaffin yield.

[0101] (3) The method used in this application is hydrothermal crystallization and conventional impregnation, and the preparation process is simple and economical. Description of the Drawings

[0102] Figure 1It is the standard X-ray diffraction (XRD) pattern of ZSM-48 molecular sieve and the XRD patterns of the molecular sieves prepared in Examples 1 to 5.

[0103] Figure 2 It is the scanning electron microscope (SEM) picture of the pure-phase ZSM-48 molecular sieve prepared in Example 1, and the scale bar is 100 nm.

[0104] Figure 3 It is the transmission electron microscope (TEM) picture of the pure-phase ZSM-48 molecular sieve prepared in Example 1 of this application, and the scale bar is 0.5 μm. Detailed implementation manners

[0105] The present application will be described in detail below in conjunction with examples, but the present application is not limited to these examples.

[0106] Unless otherwise specified, the raw materials in the examples of the present application are all purchased through commercial channels.

[0107] The specific information of various substances used in the examples is as follows:

[0108] Silica sol (Qingdao Ocean Chemical Co., Ltd., 30 wt% SiO2);

[0109] Silica white (Macklin, 95 wt% SiO2);

[0110] Tetraethyl orthosilicate (TEOS) (Comin Chemical Co., Ltd., >98 wt%);

[0111] Al2(SO4)3·18H2O (National Pharmaceutical Group, 98 wt%);

[0112] Al(NO3)3·9H2O (National Pharmaceutical Group, 99 wt%);

[0113] Pseudoboehmite (Macklin, 66% wt Al2O3, 33 wt% H2O);

[0114] NaOH (National Pharmaceutical Group, >96 wt%);

[0115] KOH (Comin Chemical Co., Ltd., 85 wt%);

[0116] HMBr (Aladdin, 98 wt%);

[0117] HMCl (Aladdin, 98 wt%)

[0118] n-Dodecane (Aladdin, 99.8 wt%)

[0119] High-purity hydrogen gas (Dalian Institute of Chemical Physics, 99.9 wt%)

[0120] Al2O3 (National Pharmaceutical Group, analytically pure)

[0121] Deionized water (self-made).

[0122] In the examples of this application, the conversion rate and yield are calculated as follows:

[0123] In the examples of this application, the conversion rate and yield are calculated as follows:

[0124]

[0125]

[0126] In the examples of this application, XRD tests were carried out using a Bruker D8 Advance X-ray diffractometer from Germany, TEM tests were carried out using a JEM-2100F instrument, and SEM tests were carried out using a JSM-7800F instrument.

[0127] Preparation Example 1 Preparation of ZSM-48 molecular sieve parent I:

[0128] Under stirring conditions, 0.16 g of Al2(SO4)3·18H2O, 1.01 g of HMBr, and 0.78 g of NaOH were dissolved in 37.29 g of H2O. After complete dissolution, 18.26 g of silica sol was added dropwise under stirring conditions. The initial gel was stirred and aged at 45 °C for 4 h, transferred to a stainless steel autoclave, placed in a rotary oven, and hydrothermally crystallized at 160 °C and 60 r / min for 48 h. After the crystallization was completed, it was quenched to room temperature with cold water, and ZSM-48 molecular sieve parent I with a silica-alumina ratio of 315 was obtained through filtration, washing, drying, and calcination.

[0129] SEM and N2 adsorption-desorption tests were carried out on ZSM-48 molecular sieve parent I, and the particle size of ZSM-48 molecular sieve parent I was measured to be 2 μm, and the pore volume of the micropores was 0.06 cm 3 / g, and the total pore volume was 0.10 cm 3 / g.

[0130] According to the above ratio and synthesis steps, it can be scaled up proportionally for synthesis.

[0131] Preparation Example 2 Preparation of ZSM-48 molecular sieve parent II:

[0132] Under stirring conditions, 3.08 g of HMOH and 0.20 g of NaOH were dissolved in 50 g of H2O. After complete dissolution, 5.84 g of white carbon black was added dropwise under stirring conditions. The initial gel was stirred and aged at 40 °C for 4 h, transferred to a stainless steel autoclave, placed in a rotary oven, and hydrothermally crystallized at 125 °C and 60 r / min for 96 h. After the crystallization was completed, it was quenched to room temperature with cold water, and ZSM-48 molecular sieve parent II with a silica-alumina ratio of 3980 was obtained through filtration, washing, drying, and calcination.

[0133] The ZSM-48 zeolite parent II was subjected to SEM and N2 adsorption-desorption tests. The particle size of the ZSM-48 zeolite parent II was measured to be 500 nm, and the pore volume of the micropores was 0.06 cm 3 / g, and the total pore volume was 0.15 cm 3 / g.

[0134] According to the above ratio and synthesis steps, it can be synthesized in an equal proportion and scaled up.

[0135] Example 1

[0136] 0.78 g of NaOH, 0.13 g of Al2(SO4)3·18H2O, and 2.17 g of HMBr were dissolved in 60 g of water to prepare a mother liquor. 3.00 g of the ZSM-48 zeolite parent I obtained in Preparation Example 1 was added to the mother liquor. It was aged for 3 h under stirring at 30 °C, transferred to a 100 ml stainless steel autoclave, placed in a rotary oven, and hydrothermally crystallized at 160 °C and 60 r / min for 96 h. After the crystallization was completed, it was quenched to room temperature with cold water, and the as-synthesized zeolite powder I in sodium form was obtained through filtration, washing, and drying. The XRD pattern of this zeolite powder I is as Figure 1 shown, which is a pure-phase ZSM-48 zeolite. From the SEM and TEM images ( Figure 2 , Figure 3 ), this pure-phase ZSM-48 zeolite is an ellipsoidal crystal with a hierarchical pore structure, with a crystal length of 4.0 μm and a width of 3.0 μm. The BET surface area measured by N2 adsorption-desorption is 238 m 2 / g, and the total pore volume is 0.32 cm 3 / g. The silicon-aluminum ratio (molar ratio of SiO2 to Al2O3) measured by XRF is 84.

[0137] According to the above ratio and synthesis steps, it can be synthesized in an equal proportion and scaled up.

[0138] The as-synthesized zeolite powder I was calcined at 550 °C for 4 h in an air atmosphere, and then ion-exchanged with 1 mol / L NH4Cl solution at 90 °C for 4 h to obtain the desired hydrogen-form zeolite. 20.0 g of this hydrogen-form zeolite and 5.0 g of pseudo-boehmite were extruded into pellets, dried at 120 °C for 2 h, and calcined at 550 °C in an air atmosphere for 4 h to obtain a catalyst support, where the addition amount of the binder was 15 wt% of the total mass of the catalyst. Using nickel nitrate as the metal precursor, the catalyst support was impregnated with an equal volume of the metal to achieve the metal-catalyst support complexation, and the metal loading was 3.5 wt%. After air drying at room temperature, it was calcined at 400 °C for 3 h in an air atmosphere. The mass of the hydrogen-form zeolite in the catalyst was 82.2 wt% of the total mass of the catalyst.

[0139] Example 2

[0140] The spherical or ellipsoidal hydrogen-form ZSM-48 molecular sieve used in this example is the same as that in Example 1.

[0141] 20.0 g of this hydrogen-form molecular sieve and 5.0 g of pseudoboehmite were extruded into pellets, dried at 120 °C for 2 h, and calcined in air atmosphere at 550 °C for 4 h to obtain a catalyst support, where the addition amount of the binder was 15 wt% of the total mass of the catalyst. Using chloroplatinic acid as the metal precursor, the catalyst support and the metal were compounded by the equal-volume impregnation method, and the metal loading was 0.5 wt%. After air drying at room temperature, it was calcined at 300 °C for 3 h in air atmosphere. The mass of the hydrogen-form molecular sieve in the catalyst was 84.5 wt% of the total mass of the catalyst.

[0142] Example 3

[0143] 2.05 g of KOH, 0.14 g of pseudoboehmite, and 2.20 g of HMBr were dissolved in 80 g of water to form a mother liquor. 2.67 g of the ZSM-48 molecular sieve precursor I obtained in Preparation Example 1 was added to the mother liquor. It was aged for 2 h under stirring at 50 °C, transferred to a 100 ml stainless steel autoclave, placed in a rotary oven, and hydrothermally crystallized at 175 °C and 60 r / min for 120 h. After the crystallization was completed, it was quenched to room temperature with cold water, and the sodium-form molecular sieve powder III was obtained through filtration, washing, and drying. The XRD pattern of this molecular sieve powder III (see Figure 1 ) confirmed that it was a pure-phase ZSM-48 molecular sieve. The morphology of this pure-phase ZSM-48 molecular sieve was similar to that in Example 1, being an ellipsoidal crystal with a cavity structure. The BET surface area measured by N2 adsorption-desorption was 308 m 2 / g, and the total pore volume was 0.47 cm 3 / g. The silicon-aluminum ratio (Si / Al2) measured by XRF was 35.

[0144] According to the above ratio and synthesis steps, it can be synthesized in equal proportion by scale-up.

[0145] The molecular sieve powder I was calcined at 550 °C for 4 h in air atmosphere, and then ion-exchanged with 1 mol / L NH4Cl solution at 90 °C for 4 h to obtain the required hydrogen-form molecular sieve.

[0146] 20.0 g of this hydrogen-form molecular sieve and 5.0 g of pseudoboehmite were extruded into pellets, dried at 120 °C for 2 h, and calcined in air atmosphere at 550 °C for 4 h to obtain a catalyst support, where the addition amount of the binder was 15 wt% of the total mass of the catalyst. Using nickel nitrate as the metal precursor, the catalyst support and the metal were compounded by the equal-volume impregnation method, and the metal loading was 5.0 wt%. After air drying at room temperature, it was calcined at 400 °C for 3 h. The mass of the hydrogen-form molecular sieve in the catalyst was 82.0 wt% of the total mass of the catalyst.

[0147] Example 4

[0148] Dissolve 0.66 g of KOH, 1.35 g of AlCl₃·6H₂O, and 7.56 g of HMOH solution in 74.32 g of water to prepare a mother liquor. Weigh 2.67 g of the ZSM-48 molecular sieve parent II obtained in Preparation Example 2 and add it to the mother liquor. Age for 8 h under stirring conditions at 30 °C, transfer it to a 100 ml stainless steel autoclave, place it in a rotary oven, and hydrothermally crystallize at 145 °C and 60 r / min for 96 h. After the crystallization is completed, quickly cool it to room temperature with cold water, and obtain the sodium-type molecular sieve raw powder IV through filtration, washing, and drying. The XRD pattern of this molecular sieve raw powder IV (see Figure 1 ) confirms that it is a pure-phase ZSM-48 molecular sieve. The morphology of this pure-phase ZSM-48 molecular sieve is similar to that of Example 1, being spherical crystals with a cavity structure, and the crystal diameter is about 500 nm. The BET surface area measured by N₂ adsorption-desorption is 318 m 2 / g, and the total pore volume is 0.52 cm 3 / g. The silicon-aluminum ratio (Si / Al₂) measured by XRF is 60.

[0149] According to the above ratio and synthesis steps, it can be synthesized in an equal proportion and scaled up.

[0150] Calcine the molecular sieve raw powder I at 550 °C for 4 h in an air atmosphere, and then perform ion exchange with 1 mol / L NH₄Cl solution at 90 °C for 4 h to obtain the required hydrogen-type molecular sieve

[0151] Extrude and form 20.0 g of this hydrogen-type molecular sieve and 5.0 g of pseudo-boehmite, dry at 120 °C for 2 h, and calcine at 550 °C in an air atmosphere for 4 h to obtain a catalyst support, where the addition amount of the binder is 15 wt% of the total mass of the catalyst. Using nickel nitrate as the metal precursor, use the equal-volume impregnation method to achieve the compounding of the catalyst support and the metal, and the metal loading is 3.5 wt%. After drying at room temperature, calcine at 400 °C for 3 h. The mass of the hydrogen-type molecular sieve in the catalyst is 82.2 wt% of the total mass of the catalyst.

[0152] Example 5

[0153] Dissolve 0.80 g of NaOH and 2.90 g of HMBr in 80 g of water to prepare a mother liquor. Weigh 4.00 g of the ZSM-48 molecular sieve parent I obtained in Preparation Example 1 and add it to the mother liquor. Age for 3 h under stirring conditions at 30 °C, transfer it to a 100 ml stainless steel autoclave, place it in a rotary oven, and hydrothermally crystallize at 160 °C and 60 r / min for 96 h. After the crystallization is completed, quickly cool it to room temperature with cold water, and obtain the sodium-type molecular sieve raw powder V through filtration, washing, and drying. The XRD pattern of the molecular sieve raw powder V (see Figure 1)It is confirmed to be pure-phase ZSM-48 molecular sieve. The product morphology is similar to that of Example 1, being ellipsoidal crystals with a cavity structure. The BET surface area measured by N2 adsorption-desorption is 249 m 2 / g, and the total pore volume is 0.48 cm 3 / g. The silicon-aluminum ratio (Si / Al2) measured by XRF is 129.

[0154] According to the above ratio and synthesis steps, it can be synthesized in an equal proportion on a larger scale.

[0155] The molecular sieve raw powder I can be calcined at 550 °C for 4 h in an air atmosphere, and then ion-exchanged with 1 mol / L NH4Cl solution at 90 °C for 4 h to obtain the required hydrogen-type molecular sieve.

[0156] 20.0 g of this hydrogen-type molecular sieve and 5.0 g of pseudo-boehmite are extruded into pellets, dried at 120 °C for 2 h, and calcined in an air atmosphere at 550 °C for 4 h to obtain a catalyst support, where the addition amount of the binder is 15 wt% of the total mass of the catalyst. Using nickel nitrate as the metal precursor, the support and the metal are compounded by the equal-volume impregnation method, and the metal loading is 2.5 wt%. After drying at room temperature, it is calcined at 400 °C for 3 h.

[0157] The mass of the hydrogen-type molecular sieve in the catalyst is 83.0 wt% of the total mass of the catalyst.

[0158] Verification of catalytic performance:

[0159] The chain alkane isomerization catalysts obtained in Examples 1 to 5 are crushed into 20-40 mesh particles for standby.

[0160] The catalytic performance of the catalyst is evaluated by the hydroisomerization reaction of n-dodecane. The reactant raw material is 99.8 wt% n-dodecane. Before the reaction, the catalyst is activated at 500 °C (Examples 1, 3, 4, 5) / 400 °C (Example 2) for 3 h in an atmospheric-pressure hydrogen atmosphere. After the temperature is reduced to the reaction temperature, the pressure is adjusted to 2.0 MPa, and then n-dodecane is introduced into the reaction system by a double-plunger pump to start the reaction. During the reaction, the volume ratio of hydrogen to n-dodecane is maintained at 10.

[0161] The results are shown in Table 1.

[0162] Table 1 Catalytic performance of the catalysts in Examples 1 to 5

[0163] Reaction temperature / °C <![CDATA[Mass space velocity / h -1 > Conversion rate / % Yield of isododecane / % Example 1 290 1.5 91.9 85.1 Example 2 280 1.5 92.6 88.4 Example 3 295 6.0 90.8 83.5 Example 4 295 4.0 91.3 83.7 Example 5 290 1.0 91.5 84.7

[0164] As described above, these are only several embodiments of the present application and do not impose any form of limitation on the present application. Although the present application is disclosed above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art, without departing from the scope of the technical solution of the present application, making some changes or modifications using the technical content disclosed above is equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A chain alkane isomerization catalyst, characterized in that, the chain alkane isomerization catalyst comprises a hydrogen-form ZSM-48 molecular sieve, an active component and a binder; the hydrogen-form ZSM-48 molecular sieve has a spherical crystal structure or an ellipsoidal crystal structure; the hydrogen-form ZSM-48 molecular sieve has micropores and mesopores; the active component is loaded on the hydrogen-form ZSM-48 molecular sieve; the active component comprises an active element, and the active element is selected from at least one of nickel, cobalt, platinum, and palladium; the binder is selected from at least one of alumina, silica, and clay.

2. The chain alkane isomerization catalyst according to claim 1, characterized in that, the mass content of the hydrogen-form ZSM-48 molecular sieve in the chain alkane isomerization catalyst is 40-90 wt%; the mass content of the active component in the chain alkane isomerization catalyst is 0.05-10 wt%, wherein the mass of the active component is calculated based on the mass of the active element; the mass content of the binder in the chain alkane isomerization catalyst is 3-15 wt%; preferably, the silica-alumina ratio of the hydrogen-form ZSM-48 molecular sieve is 30-400; Preferably, in the hydrogen form ZSM-48 molecular sieve, the micropore volume is 0.04 to 0.09 cm 3 / g, and the mesopore volume is 0.2 to 0.8 cm 3 / g.

3. A method for preparing the chain alkane isomerization catalyst according to any one of claims 1 to 2, characterized in that, the preparation method comprises: (1) Mixing the ZSM-48 molecular sieve precursor with the mother liquor, followed by aging I, hydrothermal crystallization I, calcination I, and ion exchange to obtain the hydrogen-form ZSM-48 molecular sieve; wherein, the mother liquor comprises aluminum source I, template agent I, inorganic base I, and water I; (2) Extruding and forming the hydrogen-form ZSM-48 molecular sieve and the binder, and then calcining II to obtain a carrier; (3) Mixing an aqueous solution containing an active element precursor with the carrier, impregnating with equal volume, and calcining III to obtain the chain alkane isomerization catalyst.

4. The preparation method according to claim 3, characterized in that, in step (1), the microstructure of the ZSM-48 molecular sieve precursor is spherical or ellipsoidal; preferably, the particle size of the ZSM-48 molecular sieve precursor is 400-4000 nm; Preferably, the surface of the ZSM-48 molecular sieve parent has micropores and mesopores, and the pore volume of the micropores is 0.03 to 0.09 cm 3 / g, and the total pore volume is 0.02 to 0.25 cm 3 / g; preferably, the silica-alumina ratio of the ZSM-48 molecular sieve precursor is ≥120.

5. The preparation method according to claim 3, characterized in that, the preparation method of the ZSM-48 molecular sieve precursor comprises: aging II and hydrothermal crystallizing II an aqueous solution containing silicon source II, inorganic base II, and template agent II to obtain the ZSM-48 molecular sieve precursor; preferably, the silicon source II is selected from at least one of fumed silica, silica sol, tetraethyl orthosilicate, and water glass; preferably, the inorganic base II is selected from at least one of sodium hydroxide, sodium carbonate, potassium hydroxide, lithium hydroxide, and ammonia water; the molar ratio of the inorganic base II to the silicon source II is 0.2-0.6, wherein the molar amount of the silicon source II is calculated based on the molar amount of SiO2 in the silicon source II, and the molar amount of the inorganic base II is calculated based on the hydroxide in the inorganic base II; preferably, the template agent II is selected from at least one of hexamethylammonium bromide, hexamethylammonium chloride, and hexamethylammonium hydroxide. The molar ratio of the template agent II to the silicon source II is 0.02 to 0.3, wherein the molar amount of the template agent II is calculated based on the molar amount of hexamethonium in the template agent II, and the molar amount of the silicon source II is calculated based on the molar amount of SiO2 in the silicon source II; Preferably, the molar ratio of water to the silicon source II in the aqueous solution is 25 to 60, wherein the molar amount of the silicon source II is calculated based on the molar amount of SiO2 in the silicon source II; Preferably, the aqueous solution further contains an aluminum source II; the aluminum source II is selected from at least one of aluminum nitrate, aluminum sulfate, sodium aluminate, pseudo-boehmite, and aluminum chloride; Preferably, the molar ratio of the silicon source II to the aluminum source II is ≥120, wherein the molar amount of the aluminum source II is calculated based on the molar amount of Al2O3 in the aluminum source II; The conditions for the second aging are: the temperature is 25 to 80 °C, and the time is 2 to 8 h; Preferably, the conditions for the second hydrothermal crystallization are: dynamic crystallization, the temperature is 110 to 200 °C, and the time is 48 to 120 h.

6. The preparation method according to claim 3, wherein The mass ratio of the mother liquor to the ZSM-48 molecular sieve matrix is 5 to 70; Preferably, the aluminum source I is selected from at least one of aluminum nitrate, aluminum sulfate, sodium aluminate, pseudo-boehmite, or aluminum chloride; In the mother liquor, the concentration of the aluminum source I is 0.001 to 0.1 mol / L, wherein the concentration of the aluminum source I is based on the concentration of Al ions; Preferably, the inorganic base I is selected from at least one of sodium hydroxide, potassium hydroxide, and lithium hydroxide; In the mother liquor, the concentration of the inorganic base I is 0.1 to 0.8 mol / L, wherein the concentration of the inorganic base I is based on the concentration of OH - ; Preferably, the template agent I is selected from at least one of hexamethonium bromide, hexamethonium chloride, or hexamethonium hydroxide; In the mother liquor, the concentration of the template agent I is 0.06 to 0.45 mol / L, wherein the concentration of the template agent I is based on the concentration of hexamethonium; The conditions for the first aging are: the temperature is 30 to 80 °C, and the time is 2 to 8 h; Preferably, the conditions for the first hydrothermal crystallization are: the temperature is 120 to 200 °C, and the time is 48 to 200 h; Preferably, the conditions for the first calcination are: the temperature is 400 to 600 °C, and the time is 1 to 8 h.

7. The preparation method according to claim 3, wherein The conditions for the second calcination are: the temperature is 300 to 500 °C, and the time is 0.5 to 6 h.

8. The preparation method according to claim 3, wherein The active element precursor is selected from at least one of nickel nitrate, nickel chloride, cobalt nitrate, cobalt chloride, chloroplatinic acid, ammonium chloroplatinate, platinum chloride, and palladium chloride; The conditions for the third calcination are: carried out in an air atmosphere, the temperature is 300 to 450 °C, and the time is 1 to 3 h.

9. A method for isomerizing linear alkanes, characterized in that The method includes: Under the condition of hydrogen I, a raw material containing linear alkanes is contacted with the pretreated linear alkane isomerization catalyst and reacts; Among them, the linear alkane is selected from at least one of normal linear alkanes with C6-C 18 ; The linear alkane isomerization catalyst is selected from the linear alkane isomerization catalysts described in any one of claims 1 to 2.

10. The method according to claim 9, wherein the pretreatment includes: the chain alkane isomerization catalyst is subjected to reduction activation in a hydrogen II atmosphere; the temperature of the reduction activation is 400 to 550 °C, and the time of the reduction activation is 1 to 5 h; Preferably, the temperature of the reaction is 200 to 370 °C; the pressure of the reaction is 0 to 4 MPa; The mass space velocity of the hydrogen I is 0.5 to 10 h -1 ; in the reaction, the volume ratio of hydrogen I to the chain alkane is 50 to 400.

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