An alkane hydroisomerization catalyst, a preparation method and application thereof

Abstract

The application discloses a kind of alkane hydrogen isomerization catalyst and its preparation method and application.The catalyst of the application includes Pt active metal component and molecular sieve carrier, wherein the number of Pt metal particles located near the mouth of molecular sieve carrier accounts for 85%~100% of the total number of Pt metal particles.The catalyst of the application is applied to alkane hydrogen isomerization reaction, and exhibits excellent target product selectivity and conversion rate.

Description

Technical Field

[0001] This invention belongs to the field of alkane isomerization reaction, specifically relating to an alkane hydroisomerization catalyst, its preparation method, and its application. Background Technology

[0002] With increasing environmental pollution and growing environmental awareness, there will be significant demand for high-quality isomerized oil blending components with low sulfur, low olefin, and low aromatic content in the future. Isomerized oil mainly originates from the isomerization reaction of normal low-carbon alkanes. This process can selectively generate high-octane isoalkanes from low-octane normal alkanes. Industrially, the alkane isomerization catalysts used are mainly intermediate-temperature metal / molecular sieve bifunctional catalytic systems. The metal active sites (Pt, Pd) mainly provide hydrogenation-dehydrogenation functions, while the molecular sieve system (including ZSM-5, MOR, Y, etc.) mainly provides acidic sites and pore shape-selective functions. Numerous studies (e.g., GUISNET M. “Ideal” bifunctional catalysis over Pt-acid zeolites[J]. Catalysis Today, 2013, 218-219: 123-134.) indicate that this process follows a typical bifunctional synergistic catalytic reaction mechanism. In an ideal isomerization reaction, n-alkanes first undergo dehydrogenation on a metal to generate n-olefins. Subsequently, the n-olefins diffuse to the acidic sites of the molecular sieve and undergo skeletal isomerization to generate isoolefin intermediates. These intermediates then return to the metal sites for hydrogenation to generate the target product, isoalkane. However, in actual reactions, the narrow micropores of the molecular sieve restrict the rapid release of olefin intermediates, leading to excessive contact between them and too many strong Brønsted acid sites within the micropores. This results in the cleavage of C3, C4, and other small molecules, hindering the efficient synthesis of isomers. Therefore, there is an urgent need to develop novel metal-molecular sieve catalytic systems to suppress the cleavage side reactions within the micropores of the molecular sieve.

[0003] In catalyst preparation, adjusting the placement of Pt metal is crucial. De Jong's research group (Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons. Nature. 2015, 528: 245-248) placed the metal sites on an alumina binder, controlling the acidic sites inside the Pt and Y molecular sieve pores to be in nanoscale contact. At this point, the olefin intermediates formed during the reaction preferentially undergo "pore-mouth catalysis," thereby maximally suppressing the cracking process of the intermediates within the micropores of the molecular sieve. Similarly, CN111215131A discloses an isomer catalyst supported on an MTW-type molecular sieve and its preparation method. During the preparation process, in-situ generated carbon deposits partially fill the micropores of the molecular sieve, shortening the pore depth and covering some of the strong B-type acidic sites within the micropores, significantly improving mass transfer between reactants and intermediates. The prepared catalyst exhibits excellent isomerization performance. However, in the traditional preparation of metal / molecular sieve bifunctional catalysts, including impregnation and ion exchange methods, after subsequent calcination and other treatments, metal Pt preferentially binds to the strong β-acid sites inside the pores. As a result, most of the Pt in the final catalyst is located inside the micropores, and olefin intermediates have to enter the micropores. The narrow micropores inside the pores greatly restrict the mass transfer process of the intermediates, and cracking side reactions cannot be avoided. Summary of the Invention

[0004] To address the problem of severe cracking side reactions in the hydrogenation isomerization process of n-alkanes in existing technologies, this invention provides an alkane hydrogenation isomerization catalyst, its preparation method, and its applications. Compared to metal / molecular sieve systems obtained by traditional preparation methods, the alkane hydrogenation isomerization catalyst of this invention exhibits higher conversion rates and isomer product selectivity in the hydrogenation isomerization process of n-alkanes.

[0005] The first aspect of the present invention provides an alkane hydroisomerization catalyst, comprising a Pt active metal component and a molecular sieve support component; wherein the number of Pt metal particles located at the pores of the molecular sieve support accounts for 85% to 100% of the total number of Pt metal particles.

[0006] Furthermore, the molecule is selected from one or more of ZSM-5, ZSM-22, ZSM-35 or ZSM-11 containing a ten-membered ring pore structure, preferably one or more of ZSM-22 and ZSM-11.

[0007] Furthermore, based on the mass of the catalyst, the content of the Pt active metal component, calculated as Pt, is 0.01 wt% to 10.0 wt%, preferably 0.1 wt% to 2.5 wt%.

[0008] Furthermore, the average particle size of the Pt metal particles is 0.2–2.0 nm.

[0009] A second aspect of this invention provides a method for preparing an alkane hydroisomerization catalyst, comprising the following steps:

[0010] (1) Na-type molecular sieve raw powder was treated with a modifier and then calcined to obtain modified molecular sieve;

[0011] (2) The modified molecular sieve obtained in step (1) is loaded with Pt to obtain the catalyst.

[0012] Further, in step (1), the Na-type molecular sieve is selected from one or more of ZSM-5, ZSM-22, ZSM-35, or ZSM-11, which contain a ten-membered ring pore structure, preferably one or more of ZSM-22 and ZSM-11. The Si / Al molar ratio of the Na-type molecular sieve raw powder is 15-80, preferably 30-45.

[0013] Further, in step (1), the Na-type molecular sieve raw powder, based on the mass of the Na-type molecular sieve, has a Na content of 0.1wt% to 2.5wt%, preferably 1.0wt% to 2.5wt%.

[0014] Furthermore, in step (1), the specific surface area of ​​the Na-type molecular sieve raw powder is 220–630 m². 2 / g, pore volume 0.11~0.25cm 3 / g.

[0015] Further, in step (1), the concentration of the modifier solution is 0.005 mol / L to 3.5 mol / L, preferably 0.1 mol / L to 3.0 mol / L.

[0016] Furthermore, in step (1), the mass ratio of the modifier to the Na-type molecular sieve powder is 5:95 to 60:40.

[0017] Further, in step (1), the modifier is one or more of tetraethylammonium hydroxide, tetraethylammonium bromide, tetrapropylammonium hydroxide, tetrapropylammonium bromide, tetrabutylammonium hydroxide, tetrabutylammonium bromide, hexadecylammonium hydroxide, and hexadecylammonium bromide; preferably, the modifier is one or more of tetrapropylammonium hydroxide and tetrabutylammonium hydroxide.

[0018] Further, in step (1), the post-processing is carried out under stirring, and the post-processing conditions are: temperature of 25-90℃, preferably 25-60℃, and time of 5min-24h, preferably 1-10h.

[0019] Further, in step (1), after the post-processing is completed, the material undergoes filtration, washing, and drying. The filtration, washing, and drying are all conventional techniques in the field. The calcination conditions are: a temperature of 450–650°C, preferably 500–600°C, and a time of 30 min–24 h, preferably 1–6 h.

[0020] Further, in step (2), the Pt loading method is ion exchange. The modified molecular sieve and the Pt precursor solution (solid-liquid mass ratio 2:1 to 1:50) are stirred at 25 to 40°C for 0.5 to 48 hours, followed by solid-liquid separation, drying, and calcination to obtain the catalyst. Further, the solid-liquid separation, drying, and calcination are conventional operations in the art. The drying conditions are as follows: temperature 40 to 120°C, time 2 to 15 hours; the calcination conditions are as follows: temperature 350 to 500°C, time 2 to 15 hours.

[0021] Further, in step (2), the precursor of Pt is one or more of tetraammineplatinum nitrate, tetraammineplatinum chloride, tetraammineplatinum acetate or tetraammineplatinum sulfate, preferably tetraammineplatinum nitrate.

[0022] Furthermore, the Pt concentration in the Pt precursor solution was 0.001 mg. Pt / mL~10.50mg Pt / mL, preferably 1.0mg Pt / mL~5.0mg Pt / mL.

[0023] Furthermore, in the catalyst prepared by the method, the number of Pt metal particles located at the pores of the molecular sieve support accounts for 85% to 100% of the total number of Pt metal particles.

[0024] Furthermore, the catalyst prepared by the method, based on the catalyst mass, has a Pt active metal component content of 0.01 wt% to 10.0 wt%, preferably 0.1 wt% to 2.5 wt%, calculated as Pt.

[0025] Furthermore, the average particle size of the Pt metal particles is 0.2–2.0 nm.

[0026] The third aspect of this invention provides the application of the above-mentioned alkane hydroisomerization catalyst in the alkane hydroisomerization reaction.

[0027] Furthermore, the alkane is at least one of the n-alkanes having 5 to 9 carbon atoms (e.g., at least one of n-pentane, n-hexane, n-heptane, and n-octane).

[0028] Further, the reaction conditions are as follows: temperature 200–405℃, pressure 0.1–3.0 MPa, molar ratio of hydrogen to alkane 1.0–10.0, and alkane mass hourly space velocity (HHSV) 1.0–8.0 h⁻¹. -1 .

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) This invention provides an alkane hydroisomerization catalyst, comprising a Pt active metal component and a molecular sieve support component; wherein, under high-angle annular dark-field scanning transmission electron microscopy, the number of Pt metal particles located near the pores of the molecular sieve support accounts for 85% to 100% of the total number of Pt metal particles. When applied to the alkane isomerization reaction, the catalyst of this invention significantly improves the isomer selectivity and exhibits lower selectivity for cracking products.

[0031] (2) The present invention uses a specific modifier to post-treat the Na-type molecular sieve. Due to the large size of the specific modifier, it is only allowed to exchange Na on the pore opening and outer surface of the molecular sieve. This results in most of the Brønsted acid centers being located near the pore opening of the molecular sieve. Consequently, during the subsequent ion exchange method for loading Pt components, the location of the metal centers is optimized, and the proportion of metal Pt at the pore opening of the molecular sieve is significantly increased. This results in the alkane hydroisomerization catalyst exhibiting excellent selectivity for isomerization products in the alkane isomerization reaction. Detailed Implementation

[0032] To more clearly illustrate the technical solution of the present invention, the following specific embodiments are listed. However, those skilled in the art will readily understand that the description of the embodiments is for illustrative purposes only and should not, and will not, limit the invention as described in detail in the claims.

[0033] In this invention, a high-angle annular dark-field scanning transmission electron microscope was used to observe the catalyst and count the number of Pt (N) near the molecular sieve pores. M The instrument model was FEI Titan Cubed Themis G2300kV, and the total number of Pt particles counted was 400.

[0034] In this invention, the relevant parameters of the Na-type ZSM-5 molecular sieve raw powder used are as follows: SiO2 / Al2O3 = 35, specific surface area (S BET ) = 535m 2 / g, pore volume = 0.12cm 3 / g, based on mass, the Na content is 2.0wt%.

[0035] The relevant parameters of the ZSM-22 molecular sieve powder used in this invention are as follows: SiO2 / Al2O3 = 45, specific surface area (S BET ) = 525m 2 / g, pore volume = 0.20cm 3 / g, based on mass, the Na content is 2.3wt%.

[0036] In this invention, the relevant parameters of the Na-type ZSM-35 molecular sieve raw powder used are as follows: SiO2 / Al2O3 = 40, specific surface area (S BET ) = 538m 2 / g, pore volume = 0.22cm 3 / g, based on mass, the Na content is 1.3wt%.

[0037] In this invention, the relevant parameters of the Na-type ZSM-11 molecular sieve raw powder used are as follows: SiO2 / Al2O3 = 32, specific surface area (S BET ) = 625m 2 / g, pore volume = 0.18cm 3 / g, based on mass, the Na content is 1.9wt%.

[0038] In this invention, the reaction products were analyzed using an Agilent 7890B gas chromatograph.

[0039] In this invention, the formulas for calculating conversion rate and isomer selectivity are as follows:

[0040] Conversion rate = 1 - (mass of isohexane in reactants / mass of n-hexane in feed) × 100%;

[0041] Isomer selectivity = (mass of isohexane in the product / total mass of the product) × 100%.

[0042] To facilitate understanding of the present invention, the following embodiments are provided. However, these embodiments are merely for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0043] Comparative Example 1

[0044] Pt was loaded onto Na-type ZSM-5 molecular sieve raw powder using an ion exchange method. The specific method is as follows: 5 mL of 4 mg Pt was measured... Pt A Pt(NH3)4(NO3)2 solution of / mL was diluted with 35mL of deionized water, and 2g of Na-type ZSM-5 molecular sieve powder was added. The mixture was stirred at 30℃ for 24h. After filtration and washing, it was dried in a 90℃ oven for 15h, and then treated in a muffle furnace at 500℃ for 5h to obtain the catalyst of Comparative Example 1, denoted as D1. The number of Pt (N) near the molecular sieve pores in this catalyst is... MThe proportions are shown in Table 1.

[0045] Comparative Example 2

[0046] The raw Na-type ZSM-5 molecular sieve powder was placed in a 1.0 mol / L ammonium nitrate solution and stirred at 80℃ for 3 hours. After filtration and washing, the process was repeated twice. The filter cake was placed in a 90℃ oven and dried for 10 hours, and then treated in a muffle furnace at 550℃ for 6 hours to obtain the modified ZSM-5 molecular sieve.

[0047] Pt was loaded onto the modified ZSM-5 molecular sieve using an ion exchange method. The specific method is as follows: 5 mL of 4 mg Pt was measured... Pt A Pt(NH3)4(NO3)2 solution of / mL was diluted with 35mL of deionized water, and 2g of modified ZSM-5 molecular sieve was added. The mixture was stirred at 30℃ for 24h. After filtration and washing, it was dried in a 90℃ oven for 15h, and then treated in a muffle furnace at 500℃ for 5h to obtain the catalyst of Comparative Example 2, denoted as D2. The number of Pt (N) near the pore openings of the molecular sieve in this catalyst is... M The proportions are shown in Table 1.

[0048] Comparative Example 3

[0049] Na-type ZSM-22 molecular sieve powder was placed in a 1.0 mol / L ammonium nitrate solution and stirred at 80℃ for 3 hours. After filtration and washing, the process was repeated twice. The filter cake was dried in a 90℃ oven for 10 hours, followed by treatment in a muffle furnace at 550℃ for 6 hours to obtain the modified ZSM-22 molecular sieve. The modified ZSM-22 molecular sieve was then placed in a 1.5 mol / L tetrabutylammonium hydroxide solution, with a mass ratio of tetrabutylammonium hydroxide to Na-type ZSM-22 molecular sieve powder of 50:50. The mixture was stirred at 25℃ for 1 hour, filtered and washed, dried, and then treated in a muffle furnace at 600℃ for 5 hours to obtain the modified ZSM-22 molecular sieve.

[0050] Pt was loaded onto the modified ZSM-22 molecular sieve using an impregnation method. The specific method is as follows: Measure 10 mL of 2 mg... Pt A chloroplatinic acid solution of 1 / mL was mixed with 2g of modified ZSM-22 molecular sieve. After standing for 8 hours, the mixture was dried in a 90℃ oven for 15 hours, followed by treatment in a muffle furnace at 500℃ for 5 hours to obtain catalyst Comparative Example 3, denoted as D3. The number of Pt (N) near the pore openings of the molecular sieve in this catalyst is... M The proportions are shown in Table 1.

[0051] Comparative Example 4

[0052] The raw Na-type ZSM-35 molecular sieve powder was placed in a 1.0 mol / L ammonium nitrate solution and stirred at 60℃ for 24 hours. After filtration and washing, the filter cake was placed in a 90℃ oven and dried for 10 hours. Then it was treated in a muffle furnace at 550℃ for 6 hours to obtain the modified ZSM-35 molecular sieve.

[0053] Pt was loaded onto the modified ZSM-35 molecular sieve using an impregnation method. The specific method is as follows: Measure 10 mL of 3 mg... Pt A chloroplatinic acid solution of 1 / mL was mixed with 2g of modified ZSM-35 molecular sieve. After standing for 8 hours, the mixture was dried in a 90℃ oven for 15 hours, followed by treatment in a muffle furnace at 500℃ for 5 hours to obtain catalyst Comparative Example 4, denoted as D4. The number of Pt (N) near the pore openings of the molecular sieve in this catalyst is... M The proportions are shown in Table 1.

[0054] Comparative Example 5

[0055] The raw Na-type ZSM-11 molecular sieve powder was placed in a 1.0 mol / L ammonium chloride solution and stirred at 80℃ for 3 hours. After filtration and washing, the process was repeated twice. The filter cake was placed in a 90℃ oven and dried for 10 hours, and then treated in a muffle furnace at 550℃ for 6 hours to obtain the modified ZSM-11 molecular sieve.

[0056] Pt was loaded onto the modified ZSM-11 molecular sieve using an ion exchange method. The specific method is as follows: Measure 10 mL of 2 mg... Pt A Pt(NH3)4(NO3)2 solution of / mL was diluted with 35mL of deionized water, and 2g of modified ZSM-5-11 molecular sieve was added. The mixture was stirred at 50℃ for 12h. After filtration and washing, it was dried in a 90℃ oven for 15h, and then treated in a muffle furnace at 500℃ for 6h to obtain the catalyst of Comparative Example 5, denoted as D5. The number of Pt (N) near the pore openings of the molecular sieve in this catalyst is... M The proportions are shown in Table 1.

[0057] Comparative Example 6

[0058] Pt was loaded onto Na-type ZSM-11 molecular sieve raw powder using an impregnation method. The specific method is as follows: 10 mL of 2 mg Pt / mL chloroplatinic acid solution was measured, and 2 g of Na-type ZSM-11 molecular sieve raw powder was added. After standing for 8 hours, the powder was dried in a 90℃ oven for 15 hours, followed by treatment in a muffle furnace at 500℃ for 5 hours to obtain Comparative Example 6 catalyst, denoted as D6. The number of Pt particles (N) near the molecular sieve pores in this catalyst is... M The proportions are shown in Table 1.

[0059] Comparative Example 7

[0060] Na-type ZSM-5 molecular sieve raw powder was placed in a 1.0 mol / L tetrapropylammonium hydroxide solution, with a mass ratio of tetrapropylammonium hydroxide to Na-type ZSM-5 molecular sieve raw powder of 20:80. The mixture was stirred at 50°C for 15 hours, filtered, washed, and dried. Subsequently, it was treated in a muffle furnace at 550°C for 6 hours to obtain the modified ZSM-5 molecular sieve.

[0061] Pt was loaded onto the modified ZSM-5 molecular sieve obtained in Comparative Example 7 using an impregnation method. The specific method is as follows: 5 mL of a 4 mg Pt / mL chloroplatinic acid solution was measured, and 2 g of the modified ZSM-5 molecular sieve was added. After standing for 8 hours, the mixture was dried in a 90℃ oven for 15 hours, followed by treatment in a muffle furnace at 500℃ for 5 hours to obtain the catalyst of Comparative Example 7, denoted as D7. The number of Pt particles (N) near the pore openings of the molecular sieve in this catalyst is... M The proportions are shown in Table 1.

[0062] Comparative Example 8

[0063] Na-type ZSM-5 molecular sieve raw powder was placed in a 1.0 mol / L tetrapropylammonium hydroxide solution, with a mass ratio of tetrapropylammonium hydroxide to Na-type ZSM-5 molecular sieve raw powder of 20:80. After thorough stirring, the mixture was transferred to a crystallization reactor and crystallized at 170℃ for 15 hours. After filtration and washing, the mixture was dried and then treated in a muffle furnace at 550℃ for 6 hours to obtain the modified ZSM-5 molecular sieve.

[0064] Pt was loaded onto the modified ZSM-5 molecular sieve obtained in Comparative Example 8 using an ion exchange method. The specific method is as follows: 5 mL of 4 mg Pt was measured... Pt A Pt(NH3)4(NO3)2 solution of / mL was diluted with 35mL of deionized water, and 2g of modified ZSM-5 molecular sieve was added. The mixture was stirred at 30℃ for 24h. After filtration and washing, it was dried in a 90℃ oven for 15h, and then treated in a muffle furnace at 500℃ for 5h to obtain the catalyst of Comparative Example 8, denoted as D8. The number of Pt (N) near the pore openings of the molecular sieve in this catalyst is... M The proportions are shown in Table 1.

[0065]

Example 1

[0066] Na-type ZSM-5 molecular sieve raw powder was placed in a 1.0 mol / L tetrapropylammonium hydroxide solution, with a mass ratio of tetrapropylammonium hydroxide to Na-type ZSM-5 molecular sieve raw powder of 20:80. The mixture was stirred at 50°C for 5 hours, filtered, washed, and dried. Subsequently, it was treated in a muffle furnace at 550°C for 6 hours to obtain the modified ZSM-5 molecular sieve.

[0067] Pt was loaded onto the modified ZSM-5 molecular sieve obtained in Example 1 using an ion exchange method. The specific method is as follows: 5 mL of 4 mg Pt was measured... Pt A Pt(NH3)4(NO3)2 solution of / mL was diluted with 35mL of deionized water, and 2g of modified ZSM-5 molecular sieve was added. The mixture was stirred at 30℃ for 24h. After filtration and washing, it was dried in a 90℃ oven for 15h, and then treated in a muffle furnace at 500℃ for 5h to obtain the catalyst of Example 1, denoted as S1. The number of Pt (N) near the pore openings of the molecular sieve in this catalyst is... M The proportions are shown in Table 1.

[0068]

Example 2

[0069] Na-type ZSM-5 molecular sieve raw powder was placed in a 2.0 mol / L hexadecyl ammonium bromide solution, with a mass ratio of hexadecyl ammonium bromide to Na-type ZSM-5 molecular sieve raw powder of 10:90. The mixture was stirred at 40°C for 8 hours, filtered, washed, and dried. Subsequently, it was treated in a muffle furnace at 500°C for 6 hours to obtain the modified ZSM-5 molecular sieve.

[0070] Pt was loaded onto the modified ZSM-5 molecular sieve obtained in Example 2 using an ion exchange method. The specific method is as follows: 10 mL of 2 mg Pt was measured... Pt A Pt(NH3)4(NO3)2 solution of / mL was diluted with 35mL of deionized water, and 2g of modified ZSM-5 molecular sieve was added. The mixture was stirred at 30℃ for 24h. After filtration and washing, it was dried in a 90℃ oven for 15h, and then treated in a muffle furnace at 500℃ for 5h to obtain the catalyst of Example 2, denoted as S2. The number of Pt (N) near the pore openings of the molecular sieve in this catalyst is... M The proportions are shown in Table 1.

[0071]

Example 3

[0072] Na-type ZSM-22 molecular sieve raw powder was placed in a 1.5 mol / L tetrabutylammonium hydroxide solution, with a mass ratio of 50:50 between tetrabutylammonium hydroxide and Na-type ZSM-22 molecular sieve raw powder. The mixture was stirred at 25°C for 1.0 hour, filtered, washed, and dried. Subsequently, it was treated in a muffle furnace at 600°C for 5 hours to obtain the modified ZSM-22 molecular sieve.

[0073] Pt was loaded onto the modified ZSM-22 molecular sieve obtained in Example 3 using an ion exchange method. The specific method is as follows: 10 mL of 2 mg Pt was measured... PtA Pt(NH3)4(NO3)2 solution of / mL was diluted with 35mL of deionized water, and 2g of modified ZSM-22 molecular sieve was added. The mixture was stirred at 30℃ for 24h. After filtration and washing, it was dried in a 90℃ oven for 15h, and then treated in a muffle furnace at 500℃ for 5h to obtain the catalyst of Example 3, denoted as S3. The number of Pt (N) near the pore openings of the molecular sieve in this catalyst is... M The proportions are shown in Table 1.

[0074]

Example 4

[0075] Na-type ZSM-35 molecular sieve raw powder was placed in a 0.5 mol / L tetrapropylammonium hydroxide solution, with a mass ratio of tetrapropylammonium hydroxide to Na-type ZSM-35 molecular sieve raw powder of 60:40. The mixture was stirred at 40℃ for 6 hours, filtered, washed, and dried. Subsequently, it was treated in a muffle furnace at 600℃ for 5 hours to obtain the modified ZSM-35 molecular sieve.

[0076] Pt was loaded onto the modified ZSM-35 molecular sieve obtained in Example 4 using an ion exchange method. The specific method is as follows: 10 mL of 3 mg Pt was measured... Pt A Pt(NH3)4(NO3)2 solution of / mL was diluted with 35mL of deionized water, and 2g of modified ZSM-35 molecular sieve was added. The mixture was stirred at 30℃ for 24h. After filtration and washing, it was dried in a 90℃ oven for 15h, and then treated in a muffle furnace at 500℃ for 5h to obtain the catalyst of Example 4, denoted as S4. The number of Pt (N) near the pore openings of the molecular sieve in this catalyst is... M The proportions are shown in Table 1.

[0077]

Example 5

[0078] Na-type ZSM-11 molecular sieve raw powder was placed in a 3.0 mol / L tetrabutylammonium hydroxide solution, with a mass ratio of tetrabutylammonium hydroxide to Na-type ZSM-11 molecular sieve raw powder of 15:85. The mixture was stirred at 45℃ for 10 hours, filtered, washed, and dried. Subsequently, it was treated in a muffle furnace at 600℃ for 5 hours to obtain the modified ZSM-11 molecular sieve.

[0079] Pt was loaded onto the modified ZSM-11 molecular sieve obtained in Example 5 using an ion exchange method. The specific method is as follows: 10 mL of 2 mg Pt was measured... Pt A Pt(NH3)4(NO3)2 solution of / mL was diluted with 35mL of deionized water, and 2g of modified ZSM-11 molecular sieve was added. The mixture was stirred at 30℃ for 24h. After filtration and washing, it was dried in a 90℃ oven for 15h, and then treated in a muffle furnace at 550℃ for 6h to obtain the catalyst of Example 5, denoted as S5. The number of Pt (N) near the pore openings of the molecular sieve in this catalyst is... MThe proportions are shown in Table 1.

[0080]

Example 6

[0081] Na-type ZSM-11 molecular sieve raw powder was placed in a 2.5 mol / L tetrapropylammonium bromide solution, with a mass ratio of tetrapropylammonium bromide to Na-type ZSM-11 molecular sieve raw powder of 5:95. The mixture was stirred at 60℃ for 4 hours, filtered, washed, and dried. Subsequently, it was treated in a muffle furnace at 600℃ for 5 hours to obtain the modified ZSM-11 molecular sieve.

[0082] Pt was loaded onto the modified ZSM-11 molecular sieve obtained in Example 6 using an ion exchange method. The specific method is as follows: 10 mL of 2 mg Pt was measured... Pt A Pt(NH3)4(NO3)2 solution of / mL was diluted with 35mL of deionized water, and 2g of modified ZSM-11 molecular sieve was added. The mixture was stirred at 30℃ for 24h. After filtration and washing, it was dried in a 90℃ oven for 15h, and then treated in a muffle furnace at 550℃ for 6h to obtain the catalyst of Example 6, denoted as S6. The number of Pt (N) near the pore openings of the molecular sieve in this catalyst is... M The proportions are shown in Table 1.

[0083]

Example 7

[0084] Catalysts from Examples 1-6 and Comparative Examples 1-8 were pressed into tablets, sieved through a 20-40 mesh, and 0.3 g of catalyst was placed in a fixed-bed reactor. The temperature was increased from room temperature to 450°C at a rate of 10°C / min under a hydrogen atmosphere. After reduction for 2 h, the temperature was lowered to the reaction temperature for catalyst evaluation.

[0085] The catalyst evaluation conditions are as follows: temperature 240℃, pressure 2.0 MPa, hydrogen to n-hexane molar ratio 6.0, and n-hexane mass hourly space velocity (WHSV) 4.5 h⁻¹. -1 The evaluation results for each catalyst are shown in Table 1.

[0086] Table 1. Properties and evaluation results of each catalyst.

[0087]

[0088] In Table 1, N M The number of Pt metal particles at the pore openings of the molecular sieve support is represented by N, which represents the total number of Pt metal particles in the molecular sieve support.

[0089] Table 2. Average particle size of Pt metal particles in each catalyst example.

[0090]

[0091]

[0092] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A catalyst for alkane hydroisomerization, characterized in that, The catalyst comprises a Pt active metal component and a molecular sieve support component; wherein, the number of Pt metal particles located at the pores of the molecular sieve support accounts for 85% to 100% of the total number of Pt metal particles; the molecular sieve is one or more of ZSM-5, ZSM-22, ZSM-35 or ZSM-11 containing a ten-membered ring pore structure; based on the mass of the catalyst, the content of the Pt active metal component is 0.01 wt% to 10.0 wt%.

2. The catalyst according to claim 1, characterized in that, The molecular sieve is one or more of ZSM-22 and ZSM-11.

3. The catalyst according to claim 1, characterized in that, Based on the mass of the catalyst, the content of the Pt active metal component is 0.1 wt% to 2.5 wt%.

4. A method for preparing the alkane hydroisomerization catalyst according to any one of claims 1-3, comprising the following steps: (1) Na-type molecular sieve raw powder was post-treated with a modifier and then calcined to obtain modified molecular sieve; (2) The modified molecular sieve loaded with Pt obtained in step (1) is used to obtain the catalyst.

5. The preparation method according to claim 4, characterized in that, In step (1), the Si / Al molar ratio of the Na-type molecular sieve is 15~80; And / or, the Na-type molecular sieve raw powder, based on the mass of the Na-type molecular sieve, has a Na content of 0.1 wt% to 2.5 wt%.

6. The preparation method according to claim 5, characterized in that, In step (1), the Na-type molecular sieve raw powder has a Na content of 1.0 wt% to 2.5 wt%, based on the mass of the Na-type molecular sieve.

7. The preparation method according to claim 4, characterized in that, In step (1), the modifier is added in solution form, and the concentration of the modifier solution is 0.005 mol / L to 3.5 mol / L.

8. The preparation method according to claim 7, characterized in that, In step (1), the concentration of the modifier solution is 0.1 mol / L ~ 3.0 mol / L.

9. The preparation method according to claim 4, characterized in that, In step (1), the mass ratio of the modifier to the Na-type molecular sieve powder is 5:95~60:

40.

10. The preparation method according to claim 4, characterized in that, In step (1), the modifier is one or more of tetraethylammonium hydroxide, tetraethylammonium bromide, tetrapropylammonium hydroxide, tetrapropylammonium bromide, tetrabutylammonium hydroxide, tetrabutylammonium bromide, hexadecylammonium hydroxide, and hexadecylammonium bromide.

11. The preparation method according to claim 10, characterized in that, In step (1), the modifier is one or more of tetrapropylammonium hydroxide and tetrabutylammonium hydroxide.

12. The preparation method according to claim 4, characterized in that, In step (1), the post-treatment is carried out under stirring, and the post-treatment conditions are: temperature of 25~90 ℃ and time of 5 min~24 h; And / or, the calcination conditions are: a temperature of 450~650 ℃ and a time of 30 min~24 h.

13. The preparation method according to claim 12, characterized in that, In step (1), the post-processing conditions are: temperature 25~60 ℃, time 1~10 h; And / or, the calcination conditions are: a temperature of 500~600 ℃ and a time of 1~6 h.

14. The preparation method according to claim 4, characterized in that, In step (2), the loading method of Pt is ion exchange method, and the precursor of Pt used is one or more of tetraammineplatinum nitrate, tetraammineplatinum chloride, tetraammineplatinum acetate or tetraammineplatinum sulfate. The concentration of Pt in the Pt precursor solution was 0.001 mg. Pt / mL~10.50 mg Pt / mL.

15. The preparation method according to claim 14, characterized in that, The precursor of Pt is tetraammineplatinum nitrate; the concentration of Pt in the precursor solution is 1.0 mg. Pt / mL~5.0 mg Pt / mL.

16. The use of the catalyst according to any one of claims 1-3 or the catalyst prepared by any one of claims 4-15 in the hydroisomerization reaction of alkane.

17. The application according to claim 16, characterized in that, The reaction conditions are as follows: temperature 200–405 °C, pressure 0.1–3.0 MPa, molar ratio of hydrogen to alkanes 1.0–10.0, and mass hourly space velocity (HHSV) of the alkanes 1.0–8.0 h⁻¹. -1 .

Images