Non-noble metal-based bifunctional catalyst, preparation method therefor, and use thereof

Abstract

Disclosed in the present application are a non-noble metal-based bifunctional catalyst, a preparation method therefor, and the use thereof. The non-noble metal-based bifunctional catalyst comprises a support and an active component; the support is a hydrogen-type ZSM-48 molecular sieve; the active component comprises an active element, the active element being selected from among at least one of Fe, Co and Ni, and the dispersion of the active component being 5.5-40%. The catalyst is prepared by preparing an aluminum source, a templating agent, an inorganic base, a metal precursor and water into a mother solution, and then adding the parent ZSM-48 molecular sieve to the mother solution to be subjected to hydrothermal crystallization at a certain temperature. An one-step recrystallization policy is used to simultaneously construct metal sites and acid sites of the bifunctional catalyst. The bifunctional catalyst prepared by the method has advantages of high metal dispersion and good stability, and exhibits excellent catalytic activity and target product yields in chain alkane isomerization reactions.

Description

A non-noble metal-based bifunctional catalyst and its preparation method and application Technical Field

[0001] The present application relates to a non-noble metal-based bifunctional catalyst and a preparation method and application thereof, belonging to the technical field of catalytic chemistry. Background Art

[0002] Bifunctional catalytic materials based on molecular sieves and metal species are being used in a variety of catalytic applications, particularly in sequential reactions requiring distinct catalytically active sites, such as the hydrodeoxygenation of biomass platform molecules, CO2-to-hydrocarbon conversion, and the hydroisomerization of wax oils. The key to developing excellent alkane isomerization catalysts is the metal-acid balance in bifunctional catalysts. These metal components include both precious metals (Pt, Pd, Ru, etc.) and non-precious metals (Ni, Co, Mo, etc.). Precious metals Pt and Pd have been widely used in industry due to their excellent dehydrogenation / hydrogenation performance, but their scarcity has led to supply constraints and high costs. Consequently, the development of non-precious metal-based bifunctional catalysts has attracted considerable attention. However, since the dehydrogenation / hydrogenation performance of non-precious metals is far inferior to that of precious metals, they require a significantly higher loading than precious metals to achieve a balance between acid and metal sites. However, the weak polarization ability of non-precious metals leads to weak interactions with the support, and metal sintering easily occurs at higher loadings, resulting in a decrease in catalytic performance [C. Dai, K. Du, C. Song, X. Guo, 2020, 6791-133.]. Therefore, designing and developing a catalyst preparation method with high metal dispersion and good sintering resistance is key to promoting the industrial application of non-precious metal-based catalysts.

[0003] To address the drawbacks of non-precious metal-based catalysts, such as difficulty dispersing and sintering, a large number of modification methods have been developed. For example, metal doping (CN116590053A) and increasing the surface area of ​​the carrier (CN103787368A) are used. In situ introduction of metals during the zeolite crystallization process and the use of the confinement effect of zeolite micropores or intercrystalline (intracrystalline) mesopores are effective means to improve metal dispersion and sintering resistance. Exploring simple and economical in situ synthesis strategies is an extremely important topic. Summary of the Invention

[0004] The purpose of this application is to develop a non-precious metal-based bifunctional catalytic material. This method achieves the simultaneous construction of metal and acid sites in the bifunctional catalyst through a single-step recrystallization process, resulting in a simple preparation process. The resulting non-precious metal-based bifunctional catalyst exhibits high metal dispersion and strong sintering resistance.

[0005] In one aspect of the present application, a non-precious metal-based bifunctional catalyst is provided, wherein the non-precious metal-based bifunctional catalyst comprises a carrier and an active component;

[0006] The carrier is hydrogen-type ZSM-48 molecular sieve;

[0007] The active component includes an active element;

[0008] The active element is selected from at least one of Fe, Co, and Ni;

[0009] The dispersion degree of the active component is 5.5-40%.

[0010] Optionally, the dispersion degree of the active ingredient is independently selected from any value among 5.5%, 10%, 15%, 19%, 25%, 27%, 30%, 31%, 35%, 40% or the range between any two of the above.

[0011] Optionally, the catalyst has an ellipsoidal crystal structure or rod-bundle crystals.

[0012] Optionally, the particle size of the active component is 2 nm to 20 nm.

[0013] Optionally, the particle size of the active component is independently selected from any value among 2 nm, 2.5 nm, 3 nm, 5 nm, 10 nm, 15 nm, 20 nm, or a range between any two of the above values.

[0014] Optionally, the mass content of the active component in the non-noble metal-based bifunctional catalyst is 1 to 10 wt %, wherein the mass of the active component is calculated as the mass of the active element.

[0015] Optionally, the mass content of the active component in the non-precious metal-based bifunctional catalyst is independently selected from any value among 1wt%, 2wt%, 3wt%, 3.48wt%, 4.99wt%, 5.03wt%, 6wt%, 7.28wt%, 8wt%, 9wt%, 10wt% or a range value between any two of the above.

[0016] Optionally, the silicon-aluminum ratio (molar ratio of SiO2 to Al2O3) of the ZSM-48 molecular sieve is ≥30, or the ZSM-48 molecular sieve is a pure silicon molecular sieve.

[0017] Optionally, the non-precious metal-based bifunctional catalyst comprises a hydrogenated ZSM-48 molecular sieve and metal species (Fe, Co, Ni). The non-precious metal-based bifunctional catalyst is a one-step construction of the acidic sites and metal sites required for the bifunctional catalyst through a recrystallization hydrothermal synthesis strategy, and the silicon-aluminum ratio (molar ratio of SiO2 to Al2O3) of the ZSM-48 molecular sieve is 30 to ∞;

[0018] The mass content of the metal species in the non-noble metal-based bifunctional catalyst is 1 to 10 wt%;

[0019] The metal species loading amount is calculated based on the metal atomic weight in the metal precursor;

[0020] The metal species is selected from at least one of nickel nitrate, nickel chloride, cobalt nitrate, cobalt chloride, ferric nitrate, ferric chloride, and ferric sulfate.

[0021] Another aspect of the present application provides a method for preparing the above-mentioned non-precious metal-based bifunctional catalyst, which solves the above-mentioned technical problems by adopting suitable raw materials, finely adjusting the raw material composition, and adopting recrystallization hydrothermal crystallization method.

[0022] The preparation method comprises:

[0023] The ZSM-48 molecular sieve matrix and the mother liquor are mixed, and then subjected to aging II and hydrothermal crystallization II to obtain a bifunctional catalyst raw powder, which is then calcined and ion exchanged to obtain the non-noble metal-based bifunctional catalyst;

[0024] The mother liquor comprises an aluminum source II, a template II, an inorganic base II, a metal precursor and water II.

[0025] Optionally, the ZSM-48 molecular sieve matrix is ​​a silicon-alumina or all-silicon ZSM-48 molecular sieve.

[0026] Optionally, the preparation method of the ZSM-48 molecular sieve matrix includes:

[0027] The raw materials containing silicon source I, inorganic base I, and template agent I are mixed with water I, and then aged I, hydrothermally crystallized I, washed, dried, and calcined to obtain the ZSM-48 molecular sieve matrix.

[0028] Optionally, the silicon source I is selected from at least one of white carbon black, silica sol, ethyl orthosilicate, and water glass;

[0029] The inorganic base I is selected from at least one of sodium hydroxide, sodium carbonate, potassium hydroxide, lithium hydroxide, and ammonia water;

[0030] The concentration of the ammonia water is 25wt%;

[0031] The template agent I is selected from at least one of hexamethylammonium bromide, hexamethylammonium chloride, hexamethylammonium hydroxide, and 1,6-hexanediamine.

[0032] Optionally, the molar ratio of the inorganic base I to the silicon source I is 0.02 to 0.6;

[0033] The molar ratio of the template I to the silicon source I is 0.02 to 0.5;

[0034] The molar ratio of the water I to the silicon source I is 15 to 60;

[0035] Wherein, the molar amount of the silicon source I is calculated based on the molar amount of SiO2 in the selected silicon source I;

[0036] The molar amount of the template I is calculated based on the molar amount of hexamethylammonium root or the molar amount of 1,6-hexanediamine in the template I;

[0037] The molar amount of the inorganic base I is calculated based on the hydroxide in the inorganic base I.

[0038] Optionally, the molar ratio of the inorganic base I to the silicon source I is independently selected from any value among 0.02, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 or a range between any two of the above.

[0039] Optionally, the molar ratio of the template I to the silicon source I is independently selected from any value among 0.02, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, or a range between any two of the above.

[0040] Optionally, the molar ratio of the water I to the silicon source I is independently selected from any value among 15, 30, 45, 60 or a range between any two of the above.

[0041] Optionally, the raw material further contains an aluminum source I; the aluminum source I is selected from at least one of aluminum nitrate, aluminum sulfate, sodium aluminate, pseudo-boehmite, and aluminum chloride;

[0042] The molar ratio of the silicon source I to the aluminum source I is ≥50;

[0043] The molar amount of the aluminum source I is calculated based on the molar amount of Al2O3 in the aluminum source I.

[0044] Optionally, the temperature of the aging I is 25 to 80° C.;

[0045] The aging time is 2 to 8 hours.

[0046] Optionally, the temperature of the aging I is independently selected from any value among 25°C, 30°C, 40°C, 45°C, 50°C, 60°C, 70°C, 80°C or a range between any two of the above values.

[0047] Optionally, the aging time I is independently selected from any value among 2h, 4h, 6h, 8h or a range value between any two of the above.

[0048] Optionally, the hydrothermal crystallization I is dynamic crystallization;

[0049] The temperature of the hydrothermal crystallization I is 140-200°C;

[0050] The time of the hydrothermal crystallization I is 48 to 120 hours.

[0051] Optionally, the temperature of the hydrothermal crystallization I is independently selected from any value among 140° C., 160° C., 170° C., 200° C., or a range between any two of the above values.

[0052] Optionally, the time of the hydrothermal crystallization I is independently selected from any value among 48h, 64h, 72h, 100h, 120h or a range between any two of the above.

[0053] Optionally, the dynamic crystallization I is carried out in a tank reactor in a rotary oven, and the rotation speed of the rotary oven is 10 to 80 r / min.

[0054] After the crystallization is completed, the template is removed by filtering, washing, and calcining at 500° C. for 6 hours to obtain the molecular sieve matrix.

[0055] Optionally, the mass ratio of the mother liquor to the ZSM-48 molecular sieve matrix is ​​5 to 70.

[0056] Optionally, the mass ratio of the mother liquor to the ZSM-48 molecular sieve matrix is ​​independently selected from any value among 5, 10, 20, 30, 40, 50, 60, 70 or a range between any two of the above.

[0057] Optionally, the aluminum source II is selected from at least one of aluminum nitrate, aluminum sulfate, sodium aluminate, pseudo-boehmite or aluminum chloride.

[0058] Optionally, the inorganic base II is selected from at least one of sodium hydroxide, potassium hydroxide and lithium hydroxide.

[0059] Optionally, the template agent II is selected from at least one of hexamethonium bromide, hexamethonium chloride, and hexamethonium hydroxide.

[0060] Optionally, the metal precursor is selected from at least one of nickel nitrate, nickel chloride, cobalt nitrate, cobalt chloride, ferric nitrate, ferric chloride, and ferric sulfate.

[0061] Optionally, in the mother liquor, the concentration of the aluminum source II is 0.001 to 0.1 mol / L, calculated as the concentration of Al ions;

[0062] In the mother solution, the concentration of the template II is 0.06 to 0.45 mol / L;

[0063] In the mother liquor, the concentration of the inorganic base II is 0.1-0.8 mol / L, with OH - concentration meter.

[0064] Optionally, the concentration of the aluminum source II is independently selected from any value among 0.001 mol / L, 0.0019 mol / L, 0.0025, 0.055 mol / L, 0.085 mol / L, 0.1 mol / L, or a range between any two of the above values.

[0065] Optionally, the concentration of the template II is independently selected from any value among 0.06 mol / L, 0.1 mol / L, 0.15 mol / L, 0.25 mol / L, 0.45 mol / L, or a range between any two of the above values.

[0066] Optionally, the concentration of the inorganic base II is independently selected from any value among 0.1mol / L, 0.2mol / L, 0.25mol / L, 0.3mol / L, 0.4mol / L, 0.52mol / L, 0.6mol / L, 0.7mol / L, 0.8mol / L or a range between any two of the above.

[0067] Optionally, the added amount of the metal precursor is 1 wt% to 15 wt% of the ZSM-48 molecular sieve matrix, calculated based on the metal content in the metal precursor.

[0068] Optionally, the addition amount of the metal precursor is independently selected from any value among 1wt%, 3wt%, 4wt%, 5wt%, 8wt%, 9wt%, 10wt%, 12wt%, 15wt% or a range between any two of the above.

[0069] Optionally, the temperature of the aging II is 30 to 80° C.;

[0070] The aging II time is 2 to 8 hours.

[0071] Optionally, the temperature of the aging II is independently selected from any value of 30°C, 40°C, 50°C, 60°C, 70°C, 80°C or a range between any two of the above values.

[0072] Optionally, the aging II time is independently selected from any value among 2h, 3h, 4h, 5h, 6h, 7h, 8h or a range between any two of the above.

[0073] Optionally, the temperature of the hydrothermal crystallization II is 120 to 200° C.; and the time of the hydrothermal crystallization II is 48 to 120 hours.

[0074] Optionally, the temperature of the hydrothermal crystallization II is independently selected from any value among 120° C., 140° C., 160° C., 180° C., 200° C., or a range between any two of the above values.

[0075] Optionally, the time of the hydrothermal crystallization II is independently selected from any value among 48h, 60h, 72h, 84h, 96h, 108h, 120h, or a range between any two of the above.

[0076] Optionally, the hydrothermal crystallization II is dynamic crystallization under autogenous pressure;

[0077] The dynamic crystallization is carried out in a tank reactor in a rotary oven;

[0078] The rotating speed of the rotary oven is 10 to 80 r / min.

[0079] Optionally, the calcination temperature is 400-600°C;

[0080] The calcination time is 1 to 8 hours.

[0081] Optionally, the calcination temperature is independently selected from any value among 400°C, 450°C, 500°C, 520°C, 550°C, 600°C or a range between any two of the above values.

[0082] Optionally, the calcination time is independently selected from any value among 1 h, 2 h, 4 h, 6 h, 8 h, or a range between any two of the above values.

[0083] Optionally, the obtained catalyst powder is calcined at 550° C. in air atmosphere for 6 hours to remove the template, and then subjected to ion exchange to obtain the bifunctional catalyst.

[0084] Another aspect of the present application provides an application of the above-mentioned non-noble metal-based bifunctional catalyst in catalyzing the isomerization reaction of chain alkanes, wherein the application includes:

[0085] Under hydrogen I conditions, the raw material containing chain alkanes contacts with a pretreated non-noble metal-based bifunctional catalyst to undergo an isomerization reaction;

[0086] Wherein, the chain alkane is selected from C6~C 18 At least one of the normal chain alkanes.

[0087] Optionally, the pretreatment conditions are: the non-noble metal-based bifunctional catalyst is subjected to reduction activation in a hydrogen II atmosphere;

[0088] The reduction activation temperature is 450-600° C., and the reduction activation time is 1-5 hours.

[0089] Optionally, the reduction activation temperature is independently selected from any value among 450°C, 500°C, 550°C, 600°C or a range between any two of the above values.

[0090] Optionally, the reduction activation time is independently selected from any value among 1 h, 2 h, 3 h, 4 h, 5 h, or a range between any two of the above values.

[0091] Optionally, the temperature of the isomerization reaction is 200-370°C;

[0092] The pressure of the isomerization reaction is 0-4 MPa;

[0093] The mass space velocity of the hydrogen I is 0.5 to 10 h -1 ;

[0094] In the isomerization reaction, the volume ratio of hydrogen I to chain alkane is 10-400.

[0095] Optionally, the temperature of the isomerization reaction is independently selected from any value among 200°C, 250°C, 290°C, 300°C, 305°C, 350°C, 370°C or a range between any two of the above values.

[0096] Optionally, the pressure of the isomerization reaction is independently selected from any value among 0 MPa, 1 MPa, 2 MPa, 3 MPa, 4 MPa, or a range between any two of the above values.

[0097] Optionally, the mass space velocity of the hydrogen I is independently selected from 0.5h -1 , 1h -1 , 2h -1 , 4h -1 , 6h -1 , 8h -1 , 10h -1 Any value in or a range of values ​​between any two of the above.

[0098] Optionally, the volume ratio of the hydrogen I to the chain alkane is independently selected from any value among 10, 50, 100, 150, 200, 250, 300, 350, 400 or a range between any two of the above.

[0099] Optionally, as a specific embodiment, the application includes: the above-mentioned non-precious metal-based catalyst is reduced and activated under a H2 atmosphere, the temperature is lowered to the reaction temperature after activation, and then the raw material containing chain alkanes is contacted with the chain alkane isomerization catalyst for reaction.

[0100] The beneficial effects of this application include:

[0101] (1) The present application provides a method for in situ synthesis of non-precious metal-based bifunctional catalysts, which achieves the simultaneous construction of the acid center and metal center of the bifunctional catalyst in one step through a recrystallization strategy.

[0102] (2) The non-precious metal-based bifunctional catalyst prepared in this application has the advantages of high metal dispersion and strong anti-sintering ability.

[0103] (3) The method used in this application realizes the one-step construction of metal sites and acid sites, and the process is simple and economical.

[0104] (4) The bifunctional catalyst prepared by this method has the advantages of high metal dispersion and good stability. It exhibits excellent catalytic activity and target product yield in the isomerization reaction of chain alkanes. BRIEF DESCRIPTION OF THE DRAWINGS

[0105] Figure 1 is the X-ray diffraction (XRD) pattern of the bifunctional catalyst prepared in Examples 1 to 5

[0106] FIG2 is a scanning electron microscope (SEM) image of the bifunctional catalyst prepared in Example 1, with a scale of 1 μm.

[0107] FIG3 is a transmission electron microscope (TEM) image of the bifunctional catalyst prepared in Example 1, with a scale of 20 nm.

[0108] FIG4 is a SEM image of the bifunctional catalyst prepared in Example 3, with a scale of 2 μm. DETAILED DESCRIPTION

[0109] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0110] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0111] The specific information of various substances used in the examples are as follows:

[0112] Silica sol (Qingdao Ocean Chemical Co., Ltd., 30 wt% SiO2);

[0113] Silica (McLean, 95 wt% SiO2);

[0114] Tetraethyl orthosilicate (TEOS) (Kermel, >98 wt%);

[0115] Al2(SO4)3·18H2O (Sinopharm Group, 98wt%);

[0116] Al(NO3)3·9H2O (Sinopharm Group, 99wt%);

[0117] Pseudoboehmite (McLean, 66% wtAl2O3, 33 wt% H2O);

[0118] NaOH (Sinopharm Group, >96 wt%);

[0119] KOH (Kermel, 85 wt%);

[0120] HMBr (Aladdin, 98 wt%);

[0121] HMCl (Aladdin, 98 wt%)

[0122] n-Dodecane (Aladdin, 99.8wt%)

[0123] High-purity hydrogen (Dalian Institute of Chemical Physics, 99.9wt%)

[0124] Al2O3 (Sinopharm Group, analytical grade)

[0125] Deionized water (homemade).

[0126] The conversion rate and yield in the examples of this application are calculated as follows:

[0127] In the examples of the present application, a German Bruker D8 Advance X-ray diffractometer was used for XRD testing, a JEM-2100F instrument was used for TEM testing, and a JSM-7800F instrument was used for SEM testing.

[0128] Preparation Example 1

[0129] Preparation of ZSM-48 molecular sieve matrix:

[0130] Under stirring conditions, 0.16g of Al2(SO4)3·18H2O, 1.01g of HMBr, and 0.78g of NaOH were dissolved in 37.29g of H2O. After complete dissolution, 18.26g of silica sol was added dropwise under stirring. The initial gel was stirred and aged at 45°C for 4 hours. It was then transferred to a stainless steel reactor and placed in a rotary oven for hydrothermal crystallization at 170°C and 60 rpm for 60 hours. After crystallization, it was quenched to room temperature with cold water. The ZSM-48 molecular sieve precursor was obtained through filtration, washing, drying, and calcination.

[0131] According to the above ratios and synthesis steps, the synthesis can be scaled up in equal proportions.

[0132] Preparation Example 2

[0133] Preparation of ZSM-48 molecular sieve matrix:

[0134] 3.49g of HDA and 0.21g of NaOH were dissolved in 54g of H2O with stirring. After complete dissolution, 6.00g of silica was added dropwise with stirring. The initial gel was aged at 40°C with stirring for 4 hours, then transferred to a stainless steel reactor and hydrothermally crystallized in a rotary oven at 160°C and 60 rpm for 72 hours. After crystallization, the product was quenched to room temperature with cold water. The product was then filtered, washed, dried, and calcined to obtain the ZSM-48 molecular sieve precursor.

[0135] According to the above ratios and synthesis steps, the synthesis can be scaled up in equal proportions.

[0136] Example 1

[0137] 2.0g NaOH, 0.25g Al2(SO4)3·18H2O, 4.35g HMBr, and 0.74g Ni(NO3)2 were dissolved in 120g water to prepare a mother liquor. 6.00g of the precursor ZSM-48 molecular sieve obtained in Preparation Example 1 was added to the mother liquor. The mixture was aged at 30°C with stirring for 3 hours, then transferred to a 200ml stainless steel reactor and hydrothermally crystallized in a rotary oven at 160°C and 60 rpm for 96 hours. After crystallization, the mixture was quenched to room temperature with cold water, filtered, washed, and dried to obtain a sodium-type catalyst powder. The XRD pattern of this catalyst powder is shown in Figure 1, indicating pure ZSM-48 molecular sieve, with no diffraction peaks attributable to metallic Ni. The SEM image (Figure 2) shows that the catalyst is ellipsoidal crystals. The TEM image (Figure 3) shows that the metallic Ni is highly dispersed, with a diameter of approximately 2.5nm. The dispersion of metal particles in the catalyst was tested by CO pulse chemical adsorption, and the dispersion of metal Ni was found to be 30%.

[0138] The catalyst powder was calcined at 520°C in air for 4 hours and then ion-exchanged with 1 mol / L ammonium chloride solution at 90°C for 3 hours to obtain the desired hydrogen-type catalyst. XRF analysis showed that the metal Ni loading was 4.99 wt%.

[0139] Example 2

[0140] 2.0g NaOH, 0.25g Al2(SO4)3·18H2O, 4.35g HMBr, and 0.52g Ni(NO3)2 were dissolved in 120g water to prepare a mother liquor. 6.00g of the precursor ZSM-48 molecular sieve obtained in Preparation Example 1 was weighed and added to the mother liquor. The mixture was aged at 30°C with stirring for 3h, then transferred to a 200ml stainless steel reactor and hydrothermally crystallized in a rotary oven at 160°C and 60 rpm for 96h. After crystallization, the mixture was quenched to room temperature with cold water, filtered, washed, and dried to obtain a sodium-type catalyst powder. The XRD pattern of this catalyst powder is shown in Figure 1, indicating pure ZSM-48 molecular sieve, with no diffraction peaks attributable to metallic Ni. The catalyst morphology was similar to that in the previous example, with the metallic Ni present as highly dispersed spherical particles with a diameter of approximately 2nm. The dispersion of the metal particles in the catalyst was tested using CO pulse chemisorption, which yielded a nickel dispersion of 35%.

[0141] The catalyst powder was calcined at 550°C in air for 2 hours and then ion-exchanged with 1 mol / L ammonium chloride solution at 90°C for 3 hours to obtain the desired hydrogen-type catalyst. XRF analysis showed that the metal Ni loading was 3.48 wt%.

[0142] Example 3

[0143] 1.2g NaOH, 0.15g Al2(SO4)3·18H2O, 4.35g HMBr, and 0.74g Ni(NO3)2 were dissolved in 120g water to prepare a mother liquor. 6.00g of the precursor ZSM-48 molecular sieve obtained in Preparation Example 2 was added to the mother liquor. The mixture was aged at 30°C with stirring for 3 hours, then transferred to a 200ml stainless steel reactor and hydrothermally crystallized in a rotary oven at 160°C and 60 rpm for 96 hours. After crystallization, the mixture was quenched to room temperature with cold water, filtered, washed, and dried to obtain a sodium-type catalyst powder. The XRD pattern of this catalyst powder is shown in Figure 1, indicating pure ZSM-48 molecular sieve, with no diffraction peaks attributable to metallic Ni. The SEM image (Figure 4) shows the catalyst morphology as rod-shaped crystals with highly dispersed spherical Ni particles approximately 5.0nm in diameter. The dispersion of metal particles in the catalyst was tested by CO pulse chemical adsorption, and the dispersion of metal Ni was found to be 27%.

[0144] The catalyst powder was calcined at 500°C in air for 6 hours and ion-exchanged with 1 mol / L ammonium chloride solution at 90°C for 3 hours to obtain the desired hydrogen-type catalyst. XRF analysis showed that the metal Ni loading was 5.03 wt%.

[0145] Example 4

[0146] Dissolve 1.2g NaOH, 0.15g Al2(SO4)3·18H2O, 4.35g HMBr, and 0.52g Ni(NO3)2 in 120g water to prepare a mother liquor. Add 6.00g of the precursor ZSM-48 molecular sieve obtained in Preparation Example 2 to the mother liquor. Aged at 30°C with stirring for 3h, transferred to a 200ml stainless steel reactor, and hydrothermally crystallized in a rotary oven at 160°C, 60 rpm, for 96h. After crystallization, cool to room temperature with cold water, filter, wash, and dry to obtain a sodium-type catalyst powder. The XRD pattern of this catalyst powder is shown in Figure 1, indicating pure ZSM-48 molecular sieve, with no diffraction peaks attributable to metallic Ni species. The catalyst morphology is similar to that of Example 3, with the metallic Ni appearing as highly dispersed spherical particles with a diameter of approximately 3.0nm. The dispersion of metal particles in the catalyst was tested by CO pulse chemical adsorption, and the dispersion of metal Ni was found to be 31%.

[0147] The catalyst powder was calcined at 500°C in air for 6 hours and ion-exchanged with 1 mol / L ammonium chloride solution at 90°C for 3 hours to obtain the desired hydrogen-type catalyst. XRF analysis showed that the metal Ni loading was 5.03 wt%.

[0148] Example 5

[0149] 2.5g NaOH, 0.25g Al2(SO4)3·18H2O, 4.35g HMBr, and 1.04g Ni(NO3)2 were dissolved in 120g water to prepare a mother liquor. 6.00g of the precursor ZSM-48 molecular sieve obtained in Preparation Example 1 was added to the mother liquor. Aged at 30°C with stirring for 3h, the mixture was transferred to a 200ml stainless steel reactor and hydrothermally crystallized in a rotary oven at 160°C and 60 rpm for 96h. After crystallization, the mixture was quenched to room temperature with cold water, filtered, washed, and dried to obtain a sodium-type catalyst powder. The XRD pattern of this catalyst powder is shown in Figure 1, indicating pure ZSM-48 molecular sieve, with no diffraction peaks attributable to metallic Ni. The catalyst morphology was similar to that of Example 1, with the metallic Ni appearing as highly dispersed spherical particles with a diameter of approximately 3.0nm. The dispersion of metal particles in the catalyst was tested by CO pulse chemical adsorption, and the dispersion of metal Ni was found to be 19%.

[0150] The catalyst powder was calcined at 500°C in air for 6 hours and ion-exchanged with 1 mol / L ammonium chloride solution at 90°C for 3 hours to obtain the desired hydrogen-type catalyst. XRF analysis showed that the Ni loading was 7.28 wt%.

[0151] Catalytic performance verification:

[0152] The non-noble metal-based bifunctional catalyst obtained in Examples 1 to 5 was subjected to ion exchange and calcination to obtain a hydrogen-type catalyst, which was then formed into tablets and crushed into 20-40 mesh particles for later use.

[0153] The catalyst's catalytic performance was evaluated by the hydroisomerization reaction of n-dodecane. The starting material was 99.8 wt% n-dodecane. Before the reaction, the catalyst was activated at 550°C for 3 hours under a hydrogen atmosphere at atmospheric pressure. After the temperature dropped to the reaction temperature, the pressure was adjusted to 2.0 MPa, and n-dodecane was introduced into the reaction system using a dual-plunger pump to initiate the reaction. During the reaction, the volume ratio of hydrogen to n-dodecane was maintained at 10.

[0154] The results are shown in Table 1.

[0155] Table 1 Catalytic performance of catalysts in Examples 1 to 5

[0156] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A non-precious metal-based bifunctional catalyst, characterized in that: The non-noble metal-based bifunctional catalyst comprises a carrier and an active component; The carrier is a hydrogen-type ZSM-48 molecular sieve; The active components include active elements; The active element is selected from at least one of Fe, Co and Ni; The dispersion degree of the active component is 5.5-40%.

2. The non-noble metal-based bifunctional catalyst according to claim 1, characterized in that: The catalyst has an ellipsoidal crystal structure or rod-bundle-shaped crystals.

3. The non-noble metal-based bifunctional catalyst according to claim 1 or 2, characterized in that: The particle size of the active component is 2nm to 20nm.

4. The non-noble metal-based bifunctional catalyst according to any one of claims 1 to 3, characterized in that: The mass content of the active component in the non-noble metal-based bifunctional catalyst is 1 to 10 wt%, wherein the mass of the active component is calculated as the mass of the active element; The silicon-aluminum ratio (molar ratio of SiO2 to Al2O3) of the ZSM-48 molecular sieve is not less than 30, or the ZSM-48 molecular sieve is a pure silicon molecular sieve.

5. A method for preparing a non-noble metal-based bifunctional catalyst according to any one of claims 1 to 4, characterized in that: The preparation method comprises: The ZSM-48 molecular sieve matrix is ​​mixed with the mother liquor, and then subjected to aging II and hydrothermal crystallization II to obtain a bifunctional catalyst raw powder, and then subjected to calcination and ion exchange to obtain the non-precious metal-based bifunctional catalyst; The mother liquor comprises an aluminum source II, a template agent II, an inorganic base II, a metal precursor and water II.

6. The preparation method according to claim 5, characterized in that: The preparation method of the ZSM-48 molecular sieve matrix comprises: The raw materials containing silicon source I, inorganic base I and template agent I are mixed with water I, and then aged I and hydrothermally crystallized I to obtain the ZSM-48 molecular sieve matrix.

7. The preparation method according to claim 5 or 6, characterized in that: The silicon source I is selected from at least one of white carbon black, silica sol, ethyl orthosilicate, and water glass; The inorganic base I is selected from at least one of sodium hydroxide, sodium carbonate, potassium hydroxide, lithium hydroxide and ammonia water; The template agent I is selected from at least one of hexamethylammonium bromide, hexamethylammonium chloride, hexamethylammonium hydroxide and 1,6-hexanediamine.

8. The preparation method according to any one of claims 5 to 7, characterized in that: The molar ratio of the inorganic base I to the silicon source I is 0.02 to 0.6; The molar ratio of the template agent I to the silicon source I is 0.02 to 0.5; The molar ratio of the water I to the silicon source I is 15 to 60; Wherein, the molar amount of the silicon source I is calculated based on the molar amount of SiO2 in the selected silicon source I; The molar amount of the template I is calculated based on the molar amount of hexamethylammonium root or the molar amount of 1,6-hexanediamine in the template I; The molar amount of the inorganic base I is calculated based on the hydroxide in the inorganic base I.

9. The preparation method according to any one of claims 5 to 8, characterized in that: The raw material also contains an aluminum source I; the aluminum source I is selected from at least one of aluminum nitrate, aluminum sulfate, sodium aluminate, pseudo-boehmite, and aluminum chloride.

10. The preparation method according to any one of claims 5 to 9, characterized in that: The molar ratio of the silicon source I to the aluminum source I is ≥50; The molar amount of the aluminum source I is calculated based on the molar amount of Al2O3 in the aluminum source I.

11. The preparation method according to any one of claims 5 to 10, characterized in that: The temperature of the aging I is 25-80° C.; The aging time I is 2 to 8 hours.

12. The preparation method according to any one of claims 5 to 11, characterized in that: The hydrothermal crystallization I is dynamic crystallization; The temperature of the hydrothermal crystallization I is 140-200°C; The time of the hydrothermal crystallization I is 48 to 120 hours.

13. The preparation method according to any one of claims 5 to 12, characterized in that: The mass ratio of the mother liquor to the ZSM-48 molecular sieve matrix is ​​5-70.

14. The preparation method according to any one of claims 5 to 13, characterized in that: The aluminum source II is selected from at least one of aluminum nitrate, aluminum sulfate, sodium aluminate, pseudo-boehmite or aluminum chloride.

15. The preparation method according to any one of claims 5 to 14, characterized in that: The inorganic base II is selected from at least one of sodium hydroxide, potassium hydroxide and lithium hydroxide.

16. The preparation method according to any one of claims 5 to 15, characterized in that: The template agent II is selected from at least one of hexamethonium bromide, hexamethonium chloride and hexamethonium hydroxide.

17. The preparation method according to any one of claims 5 to 16, characterized in that: The metal precursor is selected from at least one of nickel nitrate, nickel chloride, cobalt nitrate, cobalt chloride, ferric nitrate, ferric chloride and ferric sulfate.

18. The preparation method according to any one of claims 5 to 17, characterized in that: In the mother solution, the concentration of the aluminum source II is 0.001 to 0.1 mol / L, measured as the concentration of Al ions; In the mother solution, the concentration of the template II is 0.06-0.45 mol / L; In the mother liquor, the concentration of the inorganic base II is 0.1-0.8 mol / L, with OH - concentration meter.

19. The preparation method according to any one of claims 5 to 18, characterized in that: The added amount of the metal precursor is 1wt% to 15wt% of the ZSM-48 molecular sieve matrix, calculated based on the metal content in the metal precursor.

20. The preparation method according to any one of claims 5 to 19, characterized in that: The temperature of the aging II is 30-80° C.; The aging II time is 2 to 8 hours.

21. The preparation method according to any one of claims 5 to 20, characterized in that: The temperature of the hydrothermal crystallization II is 120-200° C.; the time of the hydrothermal crystallization II is 48-120 hours.

22. The preparation method according to any one of claims 5 to 21, characterized in that: The calcination temperature is 400-600°C; The calcination time is 1 to 8 hours.

23. Use of the non-noble metal-based bifunctional catalyst according to any one of claims 1 to 4 in the isomerization reaction of chain alkanes, characterized in that: The applications include: Under hydrogen I conditions, the raw material containing chain alkanes contacts with a pretreated non-precious metal-based bifunctional catalyst to undergo an isomerization reaction; Wherein, the chain alkane is selected from C6~C 18 At least one of the normal chain alkanes.

24. The use according to claim 23, characterized in that The pretreatment conditions are as follows: the non-noble metal-based bifunctional catalyst is reduced and activated in a hydrogen II atmosphere; The reduction activation temperature is 450-600° C., and the reduction activation time is 1-5 hours.

25. The use according to claim 23 or 24, characterized in that The temperature of the isomerization reaction is 200-370°C; The pressure of the isomerization reaction is 0-4 MPa; The mass space velocity of the hydrogen I is 0.5 to 10 h -1 ; In the isomerization reaction, the volume ratio of hydrogen I to chain alkane is 10-400.

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