Non-noble metal double-loaded NiM / SAPO-11 catalyst, preparation method thereof and application of non-noble metal double-loaded NiM / SAPO-11 catalyst in n-alkane isomerization reaction

Abstract

The invention provides a non-noble metal double-loaded NiM / SAPO-11 catalyst, a preparation method thereof and an application of the non-noble metal double-loaded NiM / SAPO-11 catalyst in an isomerization reaction of n-alkanes. According to the preparation method, the SAPO-11 molecular sieve with small crystal grains and a mesoporous-microporous hierarchical pore structure is synthesized through a variable-temperature step-by-step crystallization method and by adding a mesoporous template agent; by adding the metal additive, more Ni species become an addition / dehydrogenation active phase, and the dispersity of Ni is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of molecular sieve catalytic materials, and relates to a non-noble metal dual-loaded NiM / SAPO-11 catalyst, a preparation method thereof, and an application thereof in the isomerization reaction of n-alkanes. Background Art

[0002] With the increase in the processing ratio of heavy paraffinic crude oil, the production of low-freezing diesel has been greatly restricted, and the increase in the production of low-freezing diesel has become an urgent problem for refineries. Hydroisomerizing n-alkane wax molecules into isoparaffin components with similar molecular weights can improve the low-temperature fluidity of oil products, such as the freezing point of kerosene, the pour point and cold filter plugging point of diesel, and the pour point of lubricating oil base. Similarly, the increase in the content of isoparaffins in gasoline (C5-C12) components not only helps to provide the octane number of gasoline but also improves the cleanliness of gasoline combustion. Therefore, it is necessary to prepare a high-performance hydroisomerization bifunctional catalyst.

[0003] Due to its unique pore structure of ten-membered ring elliptical straight channels and mild acidity, SAPO-11 molecular sieve is an ideal carrier for hydroisomerization catalysts. However, the application of traditional SAPO-11 molecular sieves in hydroisomerization catalysts still has certain limitations. Its micropore aperture and pore length limit its ability to promote the isomerization reaction of macromolecules. It is manifested that the diffusion resistance of reaction product molecules in the pores is large, the diffusion path becomes longer, and a certain degree of secondary cracking and pore blockage will occur, which limits the further improvement of the catalytic activity and isomerization selectivity of the catalyst. For this reason, many scholars at home and abroad have carried out some work on the modification of SAPO-11 molecular sieves or new hydroisomerization materials.

[0004] At present, the metal components widely used in n-alkane hydroisomerization bifunctional catalysts are noble metals (Pt, Pd). When noble metals are used as the metal components of hydroisomerization catalysts, there are two problems: one is that noble metals are extremely sensitive to reaction raw materials and are easily poisoned and inactivated under the action of sulfur-containing compounds in the raw materials; the other is that the price of noble metals is relatively high, which increases the preparation cost and industrial application cost of the catalyst. Finding non-noble metals to replace noble metals in the preparation of hydroisomerization catalysts has certain prospects. The transition metal Ni has been used by researchers to prepare n-alkane hydroisomerization catalysts, but the hydrogenolysis activity of Ni is too high, it is easy to agglomerate and the dispersion degree is relatively low, resulting in relatively low selectivity for the isomerization reaction. For this reason, many scholars at home and abroad have carried out a series of work on the introduction of a second metal into the single-metal Ni / SAPO-11 catalyst in terms of bimetallic components.

[0005] For example, CN117019215A provides a catalyst for the isomerization reaction of n-alkanes, using Pt and / or Pd as the first metal, and one or more of Cu, Ga, Ni, and Zn as the second metal, supported on one or more of ZSM-5, Beta, MOR, Y, and SAPO-11 molecular sieves, improving the utilization efficiency of the metal components, especially the noble metal components, enabling the catalyst to exhibit excellent conversion rate, selectivity, and stability in the alkane isomerization reaction. CN117101715A provides an amine-modified bimetal-loaded NiO-MoO3@N / SAPO-11 catalyst, which has high catalytic activity and good anti-coking performance for the hydrodeoxygenation reaction of oils and fats, and has a high selectivity for alkane products in the jet fuel fraction. However, for a bifunctional hydroisomerization catalyst with SAPO-11 molecular sieve as the carrier and non-noble metal Ni as the load, although its isomerization performance can be improved by the above method, the improvement effect is limited.

[0006] Therefore, it is necessary to provide a new catalyst for the isomerization reaction of n-alkanes to improve the above problems. Summary of the Invention

[0007] In order to solve the above technical problems, the purpose of the present invention is to provide a non-noble metal double-loaded NiM / SAPO-11 catalyst, its preparation method, and its application in the isomerization reaction of n-alkanes. The non-noble metal double-loaded NiM / SAPO-11 catalyst obtained by this preparation method has small crystal grains and hierarchical pores, smaller Ni particle size and larger Ni dispersion. The addition of the second metal M weakens the interaction between the metal active phase and the carrier, promoting the formation of more Ni species to form the hydrogenation / dehydrogenation active phase.

[0008] To achieve the above purpose, the present invention provides a preparation method of a non-noble metal double-loaded NiM / SAPO-11 catalyst, which includes: mixing a phosphorus source, an aluminum source, and water to form gel A; adding an organic amine template agent, a silicon source, and a mesoporous template agent to gel A to form gel B; performing variable-temperature stepwise crystallization on gel B; and sequentially performing first drying and first calcination on the product after variable-temperature stepwise crystallization to obtain SAPO-11 molecular sieve; impregnating the SAPO-11 molecular sieve with a nickel-containing soluble salt aqueous solution and a metal promoter-containing soluble salt aqueous solution; and sequentially performing second drying and second calcination on the impregnated product to obtain a non-noble metal double-loaded NiM / SAPO-11 catalyst; the metal promoter element in the metal promoter-containing soluble salt aqueous solution includes one or a combination of two or more of La, W, Ce, Ga, and Zr; the variable-temperature stepwise crystallization includes first-stage crystallization, second-stage crystallization, third-stage crystallization, and fourth-stage crystallization performed sequentially; the temperature of the first-stage crystallization is greater than the temperature of the second-stage crystallization > the temperature of the third-stage crystallization > the temperature of the fourth-stage crystallization.

[0009] The present invention synthesizes SAPO-11 molecular sieve with small crystal grains and mesoporous-microporous hierarchical pore structure by means of variable-temperature stepwise crystallization method and adding mesoporous template agent. The above-mentioned variable-temperature stepwise crystallization promotes nucleation by reducing the crystallization temperature, thereby further reducing the crystal grain size.

[0010] The present invention changes the electronic properties of Ni by adding metal promoters, weakens the metal-support interaction, promotes the transformation of more difficult-to-reduce Ni species into easily reducible Ni species, and makes more Ni species become the addition / dehydrogenation active phase. In addition, the metal promoter can also prevent the agglomeration of Ni and improve the dispersion of Ni.

[0011] Furthermore, the temperature of the first-stage pre-crystallization is 30-60 °C, and the time is 1-6 h; the temperature of the second-stage crystallization is 60-110 °C, and the time is 1-8 h; the temperature of the third-stage crystallization is 110-150 °C, and the time is 1-14 h; the temperature of the fourth-stage crystallization is 150-230 °C, and the time is 10-20 h.

[0012] Preferably, the temperature of the first-stage pre-crystallization is 40-50 °C, and the time is 1-6 h; the temperature of the second-stage crystallization is 80-95 °C, and the time is 2-6 h; the temperature of the third-stage crystallization is 120-140 °C, and the time is 6-12 h; the temperature of the fourth-stage crystallization is 180-200 °C, and the time is 12-16 h.

[0013] Furthermore, the aluminum source is calculated as Al2O3, the phosphorus source is calculated as P2O5, the silicon source is calculated as SiO2, and the molar ratio of the aluminum source, phosphorus source, silicon source, organic amine template agent and mesoporous template agent is 1.0: 0.4-1.0: 0.2-0.8: 0.4-2.0: 0.02-0.1.

[0014] Furthermore, the nickel-soluble salt in the nickel-containing soluble salt aqueous solution includes one or more combinations of nickel nitrate, nickel acetate and nickel chloride, preferably including nickel nitrate.

[0015] Furthermore, in the nickel-containing soluble salt aqueous solution, the content of nickel atoms is 2-6 wt%.

[0016] Furthermore, the metal-promoter-soluble salt in the metal-promoter-containing soluble salt aqueous solution can be one or more combinations of ammonium metatungstate, lanthanum nitrate, gallium nitrate, zirconium nitrate and cerium sulfate. In the metal-promoter-containing soluble salt aqueous solution, the content of metal-promoter element atoms is 4-15 wt%.

[0017] Furthermore, the phosphorus source is selected from one or more combinations of phosphoric acid, phosphorous acid and hypophosphorous acid, preferably phosphoric acid. In some specific implementation cases, the phosphorus source can adopt a phosphoric acid aqueous solution with a mass concentration of 85%.

[0018] Furthermore, the aluminum source is selected from one or more combinations of pseudo-boehmite, sodium aluminate, aluminum sulfate, and aluminum isopropoxide, preferably pseudo-boehmite and / or aluminum isopropoxide.

[0019] Furthermore, the organic amine templating agent is selected from one or more combinations of di-n-propylamine, di-isopropylamine, dimethylamine, and diethylamine, preferably di-n-propylamine and / or di-isopropylamine.

[0020] Furthermore, the silicon source is selected from one or more combinations of silica sol, silicon dioxide, and tetraethyl orthosilicate, preferably silica sol and / or silicon dioxide.

[0021] Furthermore, the mesoporous templating agent is selected from one or more combinations of dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, and hexadecyltrimethylammonium bromide, preferably dodecyltrimethylammonium bromide and / or hexadecyltrimethylammonium bromide.

[0022] Furthermore, the temperature of the first drying is 70 - 120 °C, and the time is 4 - 12 h. Preferably, the temperature of the first drying is 90 - 110 °C, and the time is 9 - 12 h.

[0023] Furthermore, the temperature of the first calcination is 500 - 700 °C, and the time is 4 - 12 h. The mesoporous templating agent can be removed during the calcination process, thereby obtaining a SAPO-11 molecular sieve containing mesoporous-microporous hierarchical pores.

[0024] Furthermore, the impregnation method is equal-volume impregnation.

[0025] Furthermore, the temperature of the second drying is 100 - 120 °C, and the time is 12 - 24 h.

[0026] Furthermore, the temperature of the second calcination is 500 - 700 °C, and the time is 4 - 12 h.

[0027] The present invention also provides a non-noble metal dual-loaded NiM / SAPO-11 catalyst, which is prepared by the aforementioned preparation method.

[0028] The present invention also provides an application of the aforementioned non-noble metal dual-loaded NiM / SAPO-11 catalyst in the isomerization reaction of n-alkanes.

[0029] Furthermore, in the isomerization reaction of n-alkanes, the reaction temperature is 280 - 400 °C, the reaction pressure is 2 - 4 MPa, the volume ratio of hydrogen to hydrocarbons is 400 - 600:1, and the liquid hourly space velocity is 2 - 6 h ～1 .

[0030] The preparation method of the NiM / SAPO-11 hydrocarbon isomerization catalyst provided by the present invention has, on the one hand, both small crystal grains and mesoporous-microporous hierarchical pores, shortening the diffusion path of alkane molecules in the molecular sieve and reducing the diffusion resistance of alkane molecules in the molecular sieve; on the other hand, the addition of metal promoters promotes the dispersion of the supported metal Ni, reduces the assembly size of Ni, and more difficult-to-reduce Ni species are transformed into easily reducible Ni species, enabling more Ni species to become the addition / dehydrogenation active phase. The NiM / SAPO-11 catalyst provided by the present invention has a high isomerization selectivity and exhibits excellent isomerization performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The XRD patterns of the SAPO-11 molecular sieve in Comparative Example 3, the SAPO-11-S molecular sieve in Comparative Example 2, and the SAPO-11-C molecular sieve in Comparative Example 1 are shown.

[0032] Figure 2 The XRD patterns of the NiW / SAPO-11 catalyst in Example 1, the NiLa / SAPO-11 catalyst in Example 2, the NiGa / SAPO-11 catalyst in Example 3, the NiCe / SAPO-11 catalyst in Example 4, the NiZr / SAPO-11 catalyst in Example 5, and the SAPO-11 molecular sieve in Example 1 are shown.

[0033] Figure 3 The N2 adsorption-desorption isotherm curves of the SAPO-11 molecular sieve in Comparative Example 3, the SAPO-11-S molecular sieve in Comparative Example 2, and the SAPO-11-C molecular sieve in Comparative Example 1 are shown.

[0034] Figure 4 The N2 adsorption-desorption isotherm curves of the NiW / SAPO-11 catalyst in Example 1, the NiLa / SAPO-11 catalyst in Example 2, the NiGa / SAPO-11 catalyst in Example 3, the NiCe / SAPO-11 catalyst in Example 4, the NiZr / SAPO-11 catalyst in Example 5, and the SAPO-11 molecular sieve in Example 1 are shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] In order to have a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the technical solutions of the present invention are described in detail below, but it should not be construed as a limitation on the scope of implementation of the present invention.

[0036] Example 1

[0037] This example provides a preparation method of a NiW / SAPO-11 catalyst, and the preparation method includes:

[0038] 12.97 g of phosphoric acid (AR, 85%), 60.75 g of deionized water and 9.565 g of n-propanol (AR, 99%) were stirred and mixed to form a solution. Then, 11 g of pseudoboehmite (AR, 70%) was added to the obtained solution and stirred for 2 hours to form Gel A.

[0039] Under stirring conditions, 3.873 g of di-n-propylamine (CP, 98%) and 3.873 g of diisopropylamine (CP, 98%) were added to Gel A and continuously stirred for 2 hours. Then, 6.76 g of acidic silica sol (30% SiO2) was slowly added, and stirring was continued vigorously for 2 hours. Then, 1.17 g of cetyltrimethylammonium bromide (AR, 99%) was slowly added, and stirring was continued for 2 hours to form Gel B.

[0040] Gel B was transferred to a polytetrafluoroethylene autoclave. The first-stage crystallization temperature was 40 °C and the crystallization time was 6 h; the second-stage crystallization temperature was 90 °C and the crystallization time was 6 h; the third-stage crystallization temperature was 140 °C and the crystallization time was 12 h; the fourth-stage crystallization temperature was 200 °C and the crystallization time was 12 h.

[0041] The crystallized product was taken out, and the solid product was separated, filtered, washed, dried at 110 °C for 12 h, and calcined at 600 °C for 8 h to obtain small-crystalline multi-porous SAPO-11 molecular sieve.

[0042] The small-crystalline multi-porous SAPO-11 molecular sieve was impregnated with nickel nitrate hexahydrate with 5 wt% NiO content and ammonium metatungstate hydrate with 15 wt% WO3 content (AR, 99.5 wt%) by equal-volume impregnation, dried at 110 °C for 12 h, and calcined at 500 °C for 4 h to obtain the NiW / SAPO-11 catalyst.

[0043] Example 2

[0044] This example provides a preparation method of a NiLa / SAPO-11 catalyst, and the preparation method includes:

[0045] 12.97 g of phosphoric acid (AR, 85%), 60.75 g of deionized water and 9.565 g of n-propanol (AR, 99%) were stirred and mixed to form a solution. Then, 11 g of pseudoboehmite (AR, 70%) was added to the obtained solution and stirred for 2 hours to form Gel A.

[0046] Under stirring conditions, 3.873 g of di-n-propylamine (CP, 98%) and 3.873 g of diisopropylamine (CP, 98%) were added to Gel A and continuously stirred for 2 hours. Then, 6.76 g of acidic silica sol (30% SiO2) was slowly added, and stirring was continued vigorously for 2 hours. Subsequently, 1.17 g of cetyltrimethylammonium bromide (AR, 99%) was slowly added, and stirring was continued for 2 hours to form Gel B.

[0047] Transfer Gel B to a polytetrafluoroethylene autoclave. The first-stage crystallization temperature is 40 °C and the crystallization time is 6 h; the second-stage crystallization temperature is 90 °C and the crystallization time is 6 h; the third-stage crystallization temperature is 140 °C and the crystallization time is 12 h; the fourth-stage crystallization temperature is 200 °C and the crystallization time is 12 h.

[0048] Take out the crystallized product, separate the solid product, filter and wash it, dry it at 110 °C for 12 h, and calcine it at 600 °C for 8 h to obtain small-crystalline mesoporous SAPO-11 molecular sieve.

[0049] An aqueous solution of soluble salts of nickel nitrate hexahydrate with 4 wt% NiO and lanthanum nitrate hexahydrate with 2 wt% La2O3 (LaN3O9·6H2O) was used for equal-volume impregnation of the above-mentioned small-crystalline mesoporous SAPO-11 molecular sieve, dried at 110 °C for 12 h, and calcined at 500 °C for 4 h to obtain the NiLa / SAPO-11 catalyst.

[0050] Example 3

[0051] This example provides a preparation method of a NiGa / SAPO-11 catalyst, and the preparation method includes:

[0052] 12.97 g of phosphoric acid (AR, 85%), 60.75 g of deionized water and 9.565 g of n-propanol (AR, 99%) were stirred and mixed to form a solution. Then, 11 g of pseudo-boehmite (AR, 70%) was added to the obtained solution and stirred for 2 hours to form Gel A.

[0053] Under stirring conditions, 3.873 g of di-n-propylamine (CP, 98%) and 3.873 g of diisopropylamine (CP, 98%) were added to Gel A and continuously stirred for 2 hours. Then, 6.76 g of acidic silica sol (30% SiO2) was slowly added, and stirring was continued vigorously for 2 hours. Subsequently, 1.17 g of cetyltrimethylammonium bromide (AR, 99%) was slowly added, and stirring was continued for 2 hours to form Gel B.

[0054] Transfer Gel B to a polytetrafluoroethylene autoclave. The first-stage crystallization temperature is 40 °C and the crystallization time is 6 h; the second-stage crystallization temperature is 90 °C and the crystallization time is 6 h; the third-stage crystallization temperature is 140 °C and the crystallization time is 12 h; the fourth-stage crystallization temperature is 200 °C and the crystallization time is 12 h.

[0055] The crystallized product was taken out, and the solid product was separated, filtered, washed, dried at 110 °C for 12 h, and calcined at 600 °C for 8 h to obtain small-crystalline mesoporous SAPO-11 molecular sieve.

[0056] An equal-volume impregnation of the above-mentioned small-crystalline mesoporous SAPO-11 molecular sieve was carried out with a soluble salt aqueous solution of nickel nitrate hexahydrate with a NiO content of 4 wt% and gallium nitrate hydrate with a Ga2O3 content of 2 wt% (Ga(NO3)3·xH2O), dried at 110 °C for 12 h, and calcined at 500 °C for 4 h to obtain the NiGa / SAPO-11 catalyst.

[0057] Example 4

[0058] This example provides a preparation method of a NiCe / SAPO-11 catalyst, and the preparation method includes:

[0059] 12.97 g of phosphoric acid (AR, 85%), 60.75 g of deionized water and 9.565 g of n-propanol (AR, 99%) were stirred and mixed to form a solution, and then 11 g of pseudoboehmite (AR, 70%) was added to the obtained solution and stirred for 2 h to form gel A.

[0060] Under stirring conditions, 3.873 g of di-n-propylamine (CP, 98%) and 3.873 g of diisopropylamine (CP, 98%) were added to gel A and continuously stirred for 2 h, and then 6.76 g of acidic silica sol (30% SiO2) was slowly added, and stirring was continued vigorously for 2 h. Then 1.17 g of cetyltrimethylammonium bromide (AR, 99%) was slowly added, and stirring was continued for 2 h to form gel B.

[0061] The gel B was transferred to a polytetrafluoroethylene reaction kettle, the first-stage crystallization temperature was 40 °C, the crystallization time was 6 h; the second-stage crystallization temperature was 90 °C, the crystallization time was 6 h; the third-stage crystallization temperature was 140 °C, the crystallization time was 12 h; the fourth-stage crystallization temperature was 200 °C, and the crystallization time was 12 h.

[0062] The crystallized product was taken out, and the solid product was separated, filtered, washed, dried at 110 °C for 12 h, and calcined at 600 °C for 8 h to obtain small-crystalline mesoporous SAPO-11 molecular sieve.

[0063] An equal-volume impregnation of the above-mentioned small-crystalline mesoporous SAPO-11 molecular sieve was carried out with a soluble salt aqueous solution of nickel nitrate hexahydrate with a NiO content of 4 wt% and cerium sulfate tetrahydrate with a CeO2 content of 2 wt% (Ce(SO4)2·4H2O), dried at 110 °C for 12 h, and calcined at 500 °C for 4 h to obtain the NiCe / SAPO-11 catalyst.

[0064] Example 5

[0065] This example provides a preparation method of a NiZr / SAPO-11 catalyst, and the preparation method includes:

[0066] Stir and mix 12.97 g of phosphoric acid (AR, 85%), 60.75 g of deionized water and 9.565 g of n-propanol (AR, 99%) to form a solution, and then add 11 g of pseudoboehmite (AR, 70%) to the obtained solution, and stir for 2 hours to form gel A.

[0067] Add 3.873 g of di-n-propylamine (CP, 98%) and 3.873 g of diisopropylamine (CP, 98%) to gel A under stirring conditions and continuously stir for 2 hours, and then slowly add 6.76 g of acidic silica sol (30% SiO2), and continue to stir vigorously for 2 hours. Then slowly add 1.17 g of cetyltrimethylammonium bromide (AR, 99%), and continue to stir for 2 hours to form gel B.

[0068] Transfer gel B to a polytetrafluoroethylene autoclave, with the first-stage crystallization temperature of 40 °C and the crystallization time of 6 h; the second-stage crystallization temperature of 90 °C and the crystallization time of 6 h; the third-stage crystallization temperature of 140 °C and the crystallization time of 12 h; the fourth-stage crystallization temperature of 200 °C and the crystallization time of 12 h.

[0069] Take out the crystallized product, separate the solid product, filter and wash it, dry it at 110 °C for 12 h, and calcine it at 600 °C for 8 h to obtain small-crystalline multi-porous SAPO-11 molecular sieve.

[0070] Impregnate the above-mentioned small-crystalline multi-porous SAPO-11 molecular sieve with an equal-volume soluble salt solution of nickel nitrate hexahydrate with a NiO content of 4 wt% and zirconium nitrate (Zr(NO3)4) with a ZrO2 content of 2 wt%, dry it at 110 °C for 12 h, and calcine it at 500 °C for 4 h to obtain a NiZr / SAPO-11 catalyst.

[0071] Comparative Example 1

[0072] This comparative example provides a preparation method of a NiW / SAPO-11-C catalyst, and the preparation method includes:

[0073] Stir and mix 12.97 g of phosphoric acid (AR, 85%), 60.75 g of deionized water and 9.565 g of n-propanol (AR, 99%) to form a solution, and then add 11 g of pseudoboehmite (AR, 70%) to the obtained solution, and stir for 2 hours to form gel A.

[0074] Under stirring conditions, 3.873 g of di-n-propylamine (CP, 98%) and 3.873 g of diisopropylamine (CP, 98%) were added to Gel A and continuously stirred for 2 hours. Then, 6.76 g of acidic silica sol (30% SiO2) was slowly added, and stirring was continued vigorously for 2 hours. Subsequently, 1.17 g of cetyltrimethylammonium bromide (AR, 99%) was slowly added, and stirring was continued for 2 hours to form Gel B.

[0075] Transfer Gel B to a polytetrafluoroethylene autoclave, with a crystallization temperature of 200 °C and a crystallization time of 36 h.

[0076] Take out the crystallized product, separate the solid product, filter and wash it, dry it at 110 °C for 12 h, and calcine it at 600 °C for 8 h to obtain hierarchical pore SAPO-11-C molecular sieve.

[0077] Equal-volume impregnation of the above hierarchical pore SAPO-11-C molecular sieve was carried out with nickel nitrate hexahydrate with a NiO content of 5 wt% and ammonium metatungstate hydrate with a WO3 content of 15 wt% (AR, 99.5 wt%). It was dried at 110 °C for 12 h and calcined at 500 °C for 4 h to obtain the NiW / SAPO-11-C catalyst. The pore structure data of the catalyst are shown in Table 1.

[0078] Comparative Example 2

[0079] This comparative example provides a preparation method of a NiW / SAPO-11-S catalyst, and the preparation method includes:

[0080] 12.97 g of phosphoric acid (AR, 85%), 60.75 g of deionized water and 9.565 g of n-propanol (AR, 99%) were stirred and mixed to form a solution. Then, 11 g of pseudo-boehmite (AR, 70%) was added to the obtained solution and stirred for 2 hours to form Gel A.

[0081] Under stirring conditions, 3.873 g of di-n-propylamine (CP, 98%) and 3.873 g of diisopropylamine (CP, 98%) were added to Gel A and continuously stirred for 2 hours. Then, 6.76 g of acidic silica sol (30% SiO2) was slowly added, and stirring was continued vigorously for 2 hours to form Gel B.

[0082] Transfer Gel B to a polytetrafluoroethylene autoclave, with a crystallization temperature of 200 °C and a crystallization time of 36 h.

[0083] Take out the crystallized product, separate the solid product, filter and wash it, dry it at 110 °C for 12 h, and calcine it at 600 °C for 8 h to obtain a conventional SAPO-11-S molecular sieve.

[0084] Nickel nitrate hexahydrate with a NiO content of 5 wt% and ammonium metatungstate hydrate with a WO3 content of 15 wt% (AR, 99.5 wt%) were used to impregnate the above SAPO-11-S molecular sieve in an equal volume. After drying at 110 °C for 12 h and calcining at 500 °C for 4 h, the NiW / SAPO-11-S catalyst was obtained.

[0085] Comparative Example 3

[0086] This comparative example provides a preparation method of a Ni / SAPO-11 catalyst, and the preparation method includes:

[0087] 12.97 g of phosphoric acid (AR, 85%), 60.75 g of deionized water and 9.565 g of n-propanol (AR, 99%) were stirred and mixed to form a solution. Then, 11 g of pseudoboehmite (AR, 70%) was added to the obtained solution and stirred for 2 h to form Gel A.

[0088] Under stirring conditions, 3.873 g of di-n-propylamine (CP, 98%) and 3.873 g of diisopropylamine (CP, 98%) were added to Gel A and continuously stirred for 2 h. Then, 6.76 g of acidic silica sol (30% SiO2) was slowly added, and stirring was continued vigorously for 2 h. Then, 1.17 g of cetyltrimethylammonium bromide (AR, 99%) was slowly added, and stirring was continued for 2 h to form Gel B.

[0089] Gel B was transferred to a polytetrafluoroethylene autoclave. The first-stage crystallization temperature was 40 °C and the crystallization time was 6 h; the second-stage crystallization temperature was 90 °C and the crystallization time was 6 h; the third-stage crystallization temperature was 140 °C and the crystallization time was 12 h; the fourth-stage crystallization temperature was 200 °C and the crystallization time was 12 h.

[0090] The crystallized product was taken out, and the solid product was separated, filtered, washed, dried at 110 °C for 12 h, and calcined at 600 °C for 8 h to obtain the SAPO-11 molecular sieve.

[0091] Nickel nitrate hexahydrate with a NiO content of 4 wt% was used to impregnate the above small-crystalline mesoporous-microporous hierarchical pore SAPO-11 molecular sieve in an equal volume. After drying at 110 °C for 12 h and calcining at 500 °C for 4 h, the Ni / SAPO-11 catalyst was obtained.

[0092] Performance characterization:

[0093] (1) S BET : It was tested by a specific surface area and pore size analyzer to analyze the specific surface area, pore volume, pore size, etc. of the molecular sieve. The sample needed to be pretreated before being put into the machine, removing organic matter, moisture and corrosive substances at high temperature, and analyzing the sample in a liquid nitrogen environment at a temperature of 77.3 K. The BET method was used to calculate the specific surface area S BET data.

[0094] (2) Mesoporous pore volume: The mesoporous pore volume was measured in the same way as above, and the pore volume and average pore diameter were calculated using the Barrett-Joyner-Halenda (BJH) method.

[0095] (3) Grain size: The crystallinity, crystal form, grain size, and degree of order of the molecular sieve can be tested using an X-ray powder diffractometer (XRD). Using CuKα as the light source, the tube voltage and tube current were 40 kV and 40 mA respectively, the step width was 0.05, and the test speed was 2° / min. The grain size was calculated by the Scherrer method from the XRD pattern.

[0096] (4) Hydroisomerization test of hydrocarbons: Using n-hexadecane as the model feedstock, the temperature was 380 °C, the H2 pressure was 4 MPa, the volume ratio of hydrogen to hydrocarbons was 400:1, and the liquid hourly space velocity was 2 h -1 , and the reaction results of the examples and comparative examples are shown in Table 2.

[0097] (5) Figure 1 Shows the XRD patterns of the SAPO-11 molecular sieve in Comparative Example 3, the SAPO-11-S molecular sieve in Comparative Example 2, and the SAPO-11-C molecular sieve in Comparative Example 1. Figure 2 Shows the XRD patterns of the NiW / SAPO-11 catalyst in Example 1, the NiLa / SAPO-11 catalyst in Example 2, the NiGa / SAPO-11 catalyst in Example 3, the NiCe / SAPO-11 catalyst in Example 4, the NiZr / SAPO-11 catalyst in Example 5, and the SAPO-11 molecular sieve in Example 1.

[0098] (6) Figure 3 Shows the N2 adsorption-desorption isotherm curves of the SAPO-11 molecular sieve in Comparative Example 3, the SAPO-11-S molecular sieve in Comparative Example 2, and the SAPO-11-C molecular sieve in Comparative Example 1. Figure 4 Shows the N2 adsorption-desorption isotherm curves of the NiW / SAPO-11 catalyst in Example 1, the NiLa / SAPO-11 catalyst in Example 2, the NiGa / SAPO-11 catalyst in Example 3, the NiCe / SAPO-11 catalyst in Example 4, the NiZr / SAPO-11 catalyst in Example 5, and the SAPO-11 molecular sieve in Example 1.

[0099] Table 1

[0100]

[0101] It can be seen from the measurement data in Table 1 that compared with Comparative Example 1 and Comparative Example 2, the SAPO-11 molecular sieve in Example 1 has a smaller crystal grain size, a larger mesopore volume and a larger specific surface area, indicating that a small-crystalline multi-porous SAPO-11 molecular sieve can be obtained by adding a mesoporous template agent and stepwise crystallization at variable temperatures.

[0102] Table 2

[0103]

[0104]

[0105] The isomer selectivity of the hydrocarbon isomerization catalyst prepared in the present invention is increased by 13.93% and 20.85% respectively compared with the conventional hydrocarbon isomerization catalysts (Comparative Example 1, Comparative Example 2), which is significantly higher than that of the comparative examples. The above results show that the small-crystalline multi-porous SAPO-11 molecular sieve provided by the present invention has more mesopores, a smaller crystal grain size and a larger specific surface area, which is beneficial to reducing the diffusion resistance and diffusion path of alkane molecules in the molecular sieve pores, thereby improving the selectivity of isoparaffins.

[0106] The isomerization selectivity of the NiM / SAPO-11 (M = La, Ga, Ce, Zr, W) catalyst is significantly higher than that of the Ni / SAPO-11 catalyst (Comparative Example 3), showing excellent isomerization performance. This is because compared with the Ni / SAPO-11 catalyst, the addition of metal promoters promotes the transformation of more difficult-to-reduce Ni species into easily reducible Ni species, increasing the number of Ni active sites and making more Ni species become the addition / dehydrogenation active phase. In addition, the metal promoter can also prevent the agglomeration of Ni species and improve the dispersion of Ni, thereby improving the selectivity of isoparaffins.

Claims

1. A method for preparing a non-precious metal dual-loaded NiM / SAPO-11 catalyst, wherein: include: Mixing a phosphorus source, an aluminum source and water to form gel A; Adding an organic amine template, a silicon source, and a mesoporous template into the gel A to form a gel B; The gel B is subjected to variable temperature step-by-step crystallization; and the product after the variable temperature step-by-step crystallization is subjected to a first drying and a first calcination in sequence to obtain a SAPO-11 molecular sieve; The SAPO-11 molecular sieve is impregnated with a nickel-containing soluble salt solution and a metal additive-containing soluble salt solution; and the impregnated product is sequentially subjected to a second drying and a second calcination to obtain a non-precious metal dual-loaded NiM / SAPO-11 catalyst; The metal elements in the soluble salt solution containing the metal additive include one or a combination of two or more of La, W, Ce, Ga and Zr; The variable temperature step crystallization includes a first stage crystallization, a second stage crystallization, a third stage crystallization and a fourth stage crystallization performed sequentially; the temperature of the first stage crystallization is greater than the temperature of the second stage crystallization> the temperature of the third stage crystallization> the temperature of the fourth stage crystallization.

2. The method for preparing the non-precious metal dual-loaded NiM / SAPO-11 catalyst according to claim 1, wherein: The temperature of the first stage crystallization is 30-60° C. and the time is 1-6 hours; and / or, The temperature of the second stage crystallization is 60-110° C. and the time is 1-8 hours; and / or, The temperature of the third stage crystallization is 110-150° C. and the time is 1-14 hours; and / or, The temperature of the fourth stage crystallization is 150-230° C. and the time is 10-20 hours.

3. The method for preparing the non-precious metal dual-loaded NiM / SAPO-11 catalyst according to claim 1, wherein: The nickel-containing soluble salt solution contains 2 to 6 wt% nickel atoms; and / or The content of metal atoms in the soluble salt solution containing the metal additive is 2-15 wt%.

4. The method for preparing the non-precious metal dual-loaded NiM / SAPO-11 catalyst according to claim 1, wherein: The phosphorus source is selected from one or a combination of two or more of phosphoric acid, phosphorous acid and hypophosphorous acid; and / or, The aluminum source is selected from one or a combination of two or more of pseudo-boehmite, sodium aluminate, aluminum sulfate and aluminum isopropoxide.

5. The method for preparing the non-precious metal dual-loaded NiM / SAPO-11 catalyst according to claim 1, wherein: The organic amine template is selected from one or a combination of two or more of di-n-propylamine, diisopropylamine, dimethylamine and diethylamine; and / or, The silicon source is selected from one or a combination of two or more of silica sol, silicon dioxide and tetraethyl orthosilicate; and / or, The mesoporous template agent is selected from one or a combination of two or more of dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide and hexadecyltrimethylammonium bromide.

6. The method for preparing the non-precious metal dual-loaded NiM / SAPO-11 catalyst according to claim 1, wherein: The aluminum source is calculated as Al2O3, the phosphorus source is calculated as P2O5, and the silicon source is calculated as SiO2. The molar ratio of the aluminum source, the phosphorus source, the silicon source, the organic amine template and the mesoporous template is 1.0: 0.4~1.0: 0.2~0.8: 0.4~2.0: 0.02~0.

1.

7. The method for preparing the non-precious metal dual-loaded NiM / SAPO-11 catalyst according to claim 1, wherein: The first drying temperature is 70 to 120° C. and the time is 4 to 12 hours; and / or, The first calcination temperature is 500-700° C. and the time is 4-12 hours; and / or, The second drying temperature is 100-120° C. and the time is 12-24 hours; and / or, The second calcination is carried out at a temperature of 500 to 700° C. and for a time of 4 to 12 hours.

8. A non-precious metal dual-loaded NiM / SAPO-11 catalyst, wherein: The method is prepared according to any one of claims 1 to 7.

9. Use of the non-precious metal dual-loaded NiM / SAPO-11 catalyst according to claim 8 in the isomerization reaction of normal alkanes.

10. Use of the non-precious metal dual-loaded NiM / SAPO-11 catalyst according to claim 9 in the isomerization reaction of normal alkanes, wherein: In the isomerization reaction of normal alkanes, the reaction temperature is 280-400°C, the reaction pressure is 2-4 MPa, the volume ratio of hydrogen to hydrocarbons is 400-600:1, and the liquid space velocity is 2-6 h ～1 .

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