C4-C8 alkane isomerization catalyst as well as preparation method and application thereof

Abstract

The invention discloses a C4-C8 alkane isomerization catalyst as well as a preparation method and application thereof. The catalyst comprises an active metal Pt, an alumina component and a molecular sieve carrier, the penta-coordinated Al < 3 + > species in the alumina component accounts for 30-70% of the total Al < 3 + > species. The catalyst provided by the invention is used for C4-C8 n-alkane isomerization hydrogenation reaction, and has high isomerization product selectivity and yield.

Description

Technical Field

[0001] The invention belongs to the field of C4-C8 alkane isomerization reaction, and specifically relates to a C4-C8 alkane isomerization catalyst and a preparation method and application thereof. Background Art

[0002] The hydroisomerization of C4-C8 light alkanes can produce clean isomerized oil with high octane number, and this process will play an increasingly important role in the future. At present, the main alkane isomerization catalyst in industry is the medium-temperature metal / molecular sieve dual-function catalytic system. Common active metals are generally precious metals such as Pt, Pd, and Ir, which mainly provide hydrogenation-dehydrogenation functions; while the molecular sieve system mainly provides acid sites and pore shape selection functions. Based on the unique pore topology and physicochemical properties of the molecular sieve, it can show excellent catalytic performance in specific alkane isomerization reactions. Recently, the de Jong research group placed Pt on alumina to regulate the metal center and the zeolite acid center to be in nanoscale contact, and the catalyst showed excellent isomerization performance (Influence of Nanoscale Intimacy and Zeolite Micropore Size on the Performance of Bifunctional Catalysts for n-Heptane Hydroisomerization. ACS Catal. 2020, 10: 14245-14257). During the reaction, the Pt / Al2O3 component mainly provides hydrogenation-dehydrogenation active sites, while the physicochemical properties of the alumina support (including specific surface area, pore volume, Al coordination state, etc.) will affect the dispersion of the Pt active center and the interaction between Pt and alumina, ultimately affecting the isomerization reaction activity and target product selectivity. Based on this consideration, designing a suitable alumina support is an effective strategy to optimize the isomerization reaction process.

[0003] CN104492407A uses NaAlO2-Al2(SO4)3 as raw material, and uses oil-ammonia column method and surfactant molding strategy containing ammonia water to prepare large pore volume (1.8-2.2mL / g) alumina. CN103172097A synthesizes an alumina carrier by nucleation crystallization isolation method, and its pore volume is 0.5-1.2mL / g, and the pore diameter is 10-30nm; CN1114290A and CN1068975A use aluminum salt or aluminate precipitation-peptization, and then use oil column method to prepare a large pore volume spherical alumina; CN113492003A discloses a method for preparing a large pore and high specific surface area alumina carrier, mixing the aluminum source, hydrochloric acid and citric acid mixed acid, and then aging, drying and roasting under the action of pore expander and coagulant to obtain the alumina carrier. Gong Jinlong's research group used aluminum isopropoxide as the aluminum source and used a steam-induced self-assembly strategy under the action of Pluronic P123 and nitric acid to prepare an alumina carrier. The alumina contains a rich pentacoordinated Al species (Al 3 + penta ), and pointed out that Al 3+ penta The role of pentacoordinate Al 3+ sites of Pt / Al2O3 catalysts in propane dehydrogenation, Fundamental Research (2022)). Bao Xinhe's research group used the Ga modification strategy to synthesize a rich pentacoordinated Al species (Al 3+ penta The effect of Al2O3 on the dehydrogenation activity of alkanes was shown by the loading of Pt on the alumina support. 3+ coordination structure on the propane dehydrogenation activity of Pt / Ga / Al2O3 catalysts.Journal ofEnergyChemistry 41(2020)93-99). Nevertheless, how to use a one-step method to prepare high surface area, large pores and Al-rich 3+ penta Alumina supports also lack effective means in the isomerization of alkanes. Similarly, in the isomerization process, Al 3+ pentaSpecies regulation of reactivity and selectivity has not yet been addressed. Summary of the invention

[0004] In view of the above problems, the present invention provides a C4-C8 alkane isomerization catalyst and its preparation method and application. The catalyst of the present invention is used for the isomerization hydrogenation reaction of C4-C8 normal alkane and has high selectivity and yield of isomerized products.

[0005] The first aspect of the present invention provides a C4-C8 alkane isomerization catalyst, the catalyst comprising an active metal Pt, an alumina component and a molecular sieve carrier; the alumina component has a penta-coordinated Al 3+ Species (Al 3+ penta ) accounts for the total Al 3+ 30% to 70% of the species, preferably 50% to 70%.

[0006] Furthermore, the specific surface area of ​​the alumina is 150.0 to 350.0 m 2 / g, preferably 250.0 to 350.0 m 2 / g.

[0007] Furthermore, the pore volume of the alumina is 0.30 to 0.70 mL / g, preferably 0.45 to 0.70 mL / g.

[0008] Furthermore, the molecular sieve is at least one selected from ZSM-5, ZSM-11, ZSM-22, ZSM-35, Beta, MOR, and Y, preferably at least one selected from ZSM-5, ZSM-11, and ZSM-22.

[0009] Furthermore, the molar ratio of SiO2 / Al2O3 in the molecular sieve is 20-150, and the specific surface area is 220-620m 2 / g, pore volume is 0.11~0.92cm 3 / g.

[0010] Furthermore, in the catalyst, the mass ratio of the molecular sieve to the alumina component is 9:1 to 1:9, preferably 3:1 to 1:3, and more preferably 1:1 to 1:0.5.

[0011] Furthermore, in the catalyst, based on the mass of the catalyst, the content of active metal Pt is 0.01% to 10.0%, preferably 0.05% to 10.0%.

[0012] Furthermore, in the catalyst, the average particle size of the active metal Pt crystal particles is 0.20 nm to 1.00 nm, preferably 0.20 nm to 0.50 nm.

[0013] In a second aspect, the present invention provides a method for preparing the above catalyst, comprising the following steps:

[0014] (1) mixing an aluminum source, a high molecular weight polymer, an inorganic acid, an alcohol and water to obtain a precursor solution;

[0015] (2) The precursor solution is subjected to heat treatment, modification treatment, and calcination to obtain aluminum oxide;

[0016] (3) adding the Pt precursor solution dropwise to the suspension of alumina obtained in step (2) to react and obtain active Pt / Al2O3;

[0017] (4) Mixing the active Pt / Al2O3 obtained in step (3) with the molecular sieve to obtain the alkane isomerization catalyst.

[0018] Furthermore, in step (1), the aluminum source is calculated as Al2O3, the high molecular weight polymer, and the inorganic acid are calculated as H + The mass ratio of alcohol and water is, that is, Al2O3: polymer: inorganic acid: alcohol: H2O = 1: 0.5~2.0: 0.5~2.0: 4.5~15: 20~50.

[0019] Furthermore, in step (1), the aluminum source is selected from one or more of aluminum chloride, aluminum nitrate, aluminum sulfate, aluminum carbonate, aluminum acetate, aluminum phosphate, aluminum oxide, aluminum isopropoxide, aluminum sol or pseudo-boehmite, preferably one or more of aluminum chloride, aluminum sulfate, aluminum nitrate, aluminum isopropoxide or aluminum sol.

[0020] Furthermore, in step (1), the high molecular polymer is selected from one or more of polyoxyethylene, polyoxypropylene, polyoxybutylene, polyoxypropylene-polyoxyethylene, polyoxyethylene-polyoxybutylene, polyoxypropylene-polyoxybutylene, polyethylene oxide, polypropylene oxide, polyethylene oxide-polypropylene oxide-polyethylene oxide (P123), preferably one or more of polyoxypropylene-polyoxyethylene, polyoxyethylene-polyoxybutylene, polyethylene oxide-polypropylene oxide-polyethylene oxide (P123).

[0021] Furthermore, in step (1), the inorganic acid is selected from at least one of hydrochloric acid, nitric acid, acetic acid, sulfuric acid, phosphoric acid, and carbonic acid, preferably at least one of nitric acid and hydrochloric acid.

[0022] Furthermore, in step (1), the alcohol is selected from at least one of methanol, ethanol, ethylene glycol, propanol and glycerol, preferably ethanol.

[0023] Furthermore, in step (2), the heat treatment is carried out under stirring, the heat treatment temperature is 30 to 90° C., preferably 30 to 50° C., and the heat treatment time is 0.5 h to 24 h, preferably 4 h to 12 h.

[0024] Furthermore, in step (2), after the heat treatment is completed, the modified material is heated in a closed environment for modification. The temperature of the modification treatment is 70 to 150° C., preferably 70 to 100° C., and the time of the modification treatment is 5 to 60 hours, preferably 24 to 40 hours.

[0025] Furthermore, the temperature of the modification treatment is 20 to 80 V higher than the temperature of the heat treatment.

[0026] Furthermore, in step (2), the calcination conditions are: the calcination temperature is 350 to 750° C., preferably 500 to 750° C.; the calcination time is 4 to 12 hours, preferably 4 to 8 hours.

[0027] Furthermore, in step (3), the Pt precursor is chloroplatinic acid.

[0028] Furthermore, the Pt concentration in the Pt precursor solution is 0.001 mg Pt / mL~2.50mg Pt / mL, preferably 0.1mg Pt / mL~1.5mg Pt / mL.

[0029] Furthermore, in step (3), the preparation process of the aluminum oxide suspension is: firstly, aluminum oxide is mixed with water, stirred for 0.1 to 1.0 h, then hydrochloric acid is slowly added dropwise to adjust the pH value to 0.5 to 3.5, and stirring is continued for 0.5 to 2.0 h.

[0030] Furthermore, in step (3), the reaction time is 0.5 to 10.5 hours. After the reaction is completed, the active Pt / Al2O3 is obtained after conventional operations such as filtration, washing, drying, and calcination. 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.

[0031] Furthermore, in step (4), the mass ratio of active Pt / Al2O3 to molecular sieve is 1:9 to 9:1, preferably 3:7 to 6:4.

[0032] Furthermore, in step (4), the mixing is physical mixing, and the mixing method includes grinding, ball milling, etc.

[0033] The third aspect of the present invention also provides the use of the above catalyst in catalyzing alkane isomerization reaction.

[0034] Furthermore, the alkane is at least one of normal alkanes having 4 to 8 carbon atoms (such as at least one of n-pentane, n-hexane, n-heptane and n-octane).

[0035] Furthermore, the conditions for the alkane isomerization reaction are preferably: temperature 180-405°C, reaction pressure 1.0-3.0 MPa, molar ratio of hydrogen to normal alkane 1.0-7.0, mass space velocity of alkane 1.5-9.5 h -1

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. The present invention provides a novel C4-C8 alkane isomerization catalyst, comprising an active metal, an alumina component and a molecular sieve, wherein the alumina component has a penta-coordinated Al 3+ Species (Al 3+ penta ) accounts for the total Al 3+ The proportion of species is X, the value of X is 30% to 70%, and its specific surface area is 150.0 to 350.0 m 2 / g, and the pore volume is 0.30-0.70mL / g. The catalyst of the present invention is applied to the isomerization hydrogenation reaction of C4-C8 normal alkanes, is conducive to the formation of isomerization products, and has higher selectivity and yield of isomerization products.

[0038] 2. On the one hand, the present invention is based on the specific modification properties of high molecular polymers, by changing its molecular composition, the proportion of the modified liquid and the subsequent processing conditions, to prepare an Al-rich 3+ penta On the other hand, after the Pt active metal is loaded on the above-mentioned alumina carrier through an electrostatic adsorption strategy and physically mixed with the molecular sieve, after comprehensive coordination of various preparation steps, the catalyst finally obtained has higher selectivity and yield of isomerized products in the isomerization hydrogenation reaction of C4-C8 normal alkanes. DETAILED DESCRIPTION

[0039] In order to more clearly illustrate the technical solution of the present invention, the following specific implementation examples are listed. However, it is easy for those skilled in the art to understand that the contents described in the embodiments are only used to illustrate the present invention, and should not and will not limit the present invention described in detail in the claims.

[0040] In the present invention, the specific surface area and pore volume of the sample are obtained by nitrogen physical adsorption test on Micromeritics ASAP 2020M. Before the test, the sample is vacuum treated at 350°C for 4 hours, and the specific surface area is calculated by the BET multi-point method in the relative pressure range of 0.05-0.25, and the pore volume and pore size are obtained by the Saito-Foley method.

[0041] In the present invention, the penta-coordinated Al 3+ Species (Al3+ penta ) accounts for the total Al 3+ The proportion of species (represented by X) is calculated using 27 The Al MAS NMR nuclear magnetic experiment was measured using a Bruker Avance III-600 with a Larmor frequency of 156.4 MHz and a Bruker 4 mm HXY MAS NMR probe with a magic angle spinning (MAS) frequency of 12 kHz. 27 The chemical shift of Al was analyzed using 1 mol / L aluminum nitrate aqueous solution as an external standard. Before the test, the alumina sample was dried in an oven to fully dehydrate.

[0042] In the present invention, the parameters of the ZSM-5 molecular sieve raw powder used are as follows: SiO2 / Al2O3=35, specific surface area (S BET )=425m 2 / g, pore volume = 0.11cm 3 / g.

[0043] In the present invention, the parameters of the ZSM-22 molecular sieve raw powder used are as follows: SiO2 / Al2O3=42, specific surface area (S BET )=325m 2 / g, pore volume = 0.22cm 3 / g.

[0044] In the present invention, the relevant parameters of the ZSM-11 molecular sieve raw powder used are as follows: SiO2 / Al2O3=30, specific surface area (S BET )=415m 2 / g, pore volume = 0.30cm 3 / g.

[0045] In the present invention, the reaction product was analyzed by Agilent 7890B gas chromatograph.

[0046] In the present invention, the calculation formulas for conversion rate, isomer selectivity and isomer yield are as follows:

[0047] Conversion rate = 1-(mass of isohexane in reactant / mass of n-hexane in feed) × 100%;

[0048] Isomer selectivity = (mass of isohexane in product / mass of product) × 100%;

[0049] Isomer yield = conversion rate × isomer selectivity × 100%.

[0050] In order to facilitate the understanding of the present invention, the present invention lists the following embodiments, but the embodiments are only used to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0051] [Comparative Example 1]

[0052] (1) A certain amount of aluminum nitrate was dissolved in a mixture of deionized water and ethanol, stirred for 30 minutes, and then 0.15 mol / L hydrochloric acid was added dropwise to obtain a precursor solution; the mass ratio of aluminum source, calculated as Al2O3, hydrochloric acid, ethanol and water was Al2O3: hydrochloric acid: ethanol: H2O = 1:2.0:15:50;

[0053] (2) The precursor solution formed in step (1) was stirred at 50°C for 8 hours, placed in a tetrafluoroethylene-lined stainless steel kettle, sealed, transferred to a 100°C oven, and kept for 24 hours; then filtered and washed, the filter cake was placed in a 90°C oven for drying for 12 hours, and then air-treated at 750°C for 6 hours to obtain Al2O3-D1, and its corresponding specific surface area, pore volume and pentacoordinate Al 3+ Species (Al 3+ penta ) accounts for the total Al 3+ The proportions of species (indicated by X) are shown in Table 1 ;

[0054] (3) Add 2g of Al2O3-D1 carrier to 100g of deionized water, stir for 1.0h, then slowly add hydrochloric acid to adjust the pH value to 3.5, and continue stirring for 2.0h. During the stirring process, add 40mL of 0.5mg Pt / mL H2PtCl6·6H2O solution, stirred for 3h, filtered and washed with 1.5L deionized water, the filter cake was dried in an oven at 100℃ for 12h, and then treated with air at 500℃ for 6h to obtain Pt / Al2O3-D1 component;

[0055] (4) 1 g of Pt / Al2O3-D1 component was mixed with 1 g of ZSM-5 molecular sieve raw powder and ground to obtain the catalyst of Comparative Example 1. The catalyst had a Pt content of 0.5%, an alumina content of 49.5%, and a molecular sieve content of 50% by mass.

[0056] [Comparative Example 2]

[0057] (1) A certain amount of aluminum nitrate was dissolved in a mixture of deionized water, ethanol and polyethylene oxide-polypropylene oxide-polyethylene oxide (P123), and stirred for 30 minutes to obtain a precursor solution; the mass ratio of aluminum source in terms of Al2O3, P123, ethanol and water was Al2O3: P123: ethanol: H2O = 1: 2.0: 15: 50;

[0058] (2) The precursor solution formed in step (1) was stirred at 50°C for 8 hours, placed in a tetrafluoroethylene-lined stainless steel kettle, sealed, transferred to a 100°C oven, and kept for 24 hours; then filtered and washed, the filter cake was placed in a 90°C oven for drying for 12 hours, and then air-treated at 750°C for 6 hours to obtain Al2O3-D2, and its corresponding specific surface area, pore volume and pentacoordinate Al 3+ Species (Al 3+ penta ) accounts for the total Al 3+ The proportions of species (indicated by X) are shown in Table 1 ;

[0059] (3) Add 2g of Al2O3-D2 carrier to 100g of deionized water, stir for 1.0h, then slowly add hydrochloric acid to adjust the pH value to 3.5, and continue stirring for 2.0h. During the stirring process, add 40mL of 0.5mg Pt / mL H2PtCl6·6H2O solution, stirred for 3h, filtered and washed with 1.5L deionized water, the filter cake was dried in an oven at 100℃ for 12h, and then treated with air at 500℃ for 6h to obtain Pt / Al2O3-D2 component;

[0060] (4) 1 g of Pt / Al2O3-D2 component was mixed with 1 g of ZSM-5 molecular sieve raw powder and ground to obtain the catalyst of Comparative Example 2. The catalyst had a Pt content of 0.5%, an alumina content of 49.5%, and a molecular sieve content of 50% by mass.

[0061] [Comparative Example 3]

[0062] (1) A certain amount of aluminum nitrate was dissolved in a mixture of deionized water, ethanol and polyethylene oxide-polypropylene oxide-polyethylene oxide (P123), and after stirring for 30 minutes, 0.15 mol / L hydrochloric acid was added dropwise to obtain a precursor solution; the mass ratio of aluminum source in terms of Al2O3, P123, hydrochloric acid, ethanol and water was Al2O3: P123: hydrochloric acid: ethanol: H2O = 1: 2.0: 2.0: 15: 50;

[0063] (2) The precursor solution formed in step (1) was stirred at 100°C for 8 hours, placed in a tetrafluoroethylene-lined stainless steel kettle, sealed, transferred to a 100°C oven, and kept for 24 hours; then filtered and washed, the filter cake was placed in a 90°C oven for drying for 12 hours, and then air-treated at 750°C for 6 hours to obtain Al2O3-D3, and its corresponding specific surface area, pore volume and pentacoordinate Al 3+ Species (Al 3+ penta ) accounts for the total Al 3+ The proportions of species (indicated by X) are shown in Table 1 ;

[0064] (3) Add 2g of Al2O3-D3 carrier to 100g of deionized water, stir for 1.0h, then slowly add hydrochloric acid to adjust the pH value to 3.5, and continue stirring for 2.0h. During the stirring process, add 40mL of 0.5mg Pt / mL H2PtCl6·6H2O solution, stirred for 3h, filtered and washed with 1.5L deionized water, the filter cake was dried in an oven at 100℃ for 12h, and then treated with air at 500℃ for 6h to obtain Pt / Al2O3-D3 component;

[0065] (4) 1 g of Pt / Al2O3-D3 component was mixed with 1 g of ZSM-5 molecular sieve raw powder and ground to obtain the catalyst of Comparative Example 3. The catalyst had a Pt content of 0.5%, an alumina content of 49.5%, and a molecular sieve content of 50% by mass.

[0066] [Comparative Example 4]

[0067] (1) A certain amount of aluminum nitrate was dissolved in a mixture of deionized water, ethanol and polyethylene oxide-polypropylene oxide-polyethylene oxide (P123), and after stirring for 30 minutes, 0.15 mol / L hydrochloric acid was added dropwise to obtain a precursor solution; the mass ratio of aluminum source in terms of Al2O3, P123, hydrochloric acid, ethanol and water was Al2O3: P123: hydrochloric acid: ethanol: H2O = 1: 2.0: 2.0: 15: 50;

[0068] (2) The precursor solution formed in step (1) was stirred at 50°C for 8 hours, placed in a tetrafluoroethylene-lined stainless steel kettle, sealed, transferred to a 170°C oven, and kept for 24 hours; then filtered and washed, the filter cake was placed in a 90°C oven for drying for 12 hours, and then air-treated at 750°C for 6 hours to obtain Al2O3-D4, and its corresponding specific surface area, pore volume and pentacoordinate Al 3+ Species (Al 3+ penta ) accounts for the total Al 3+ The proportions of species (indicated by X) are shown in Table 1 ;

[0069] (3) Add 2g of Al2O3-D4 carrier to 100g of deionized water, stir for 1.0h, then slowly add hydrochloric acid to adjust the pH value to 3.5, and continue stirring for 2.0h. During the stirring process, add 40mL of 0.5mg Pt / mL H2PtCl6·6H2O solution, stirred for 3h, filtered and washed with 1.5L deionized water, the obtained filter cake was dried in an oven at 100℃ for 12h, and then treated with air at 500℃ for 6h to obtain Pt / Al2O3-D4 component;

[0070] (4) 1 g of Pt / Al2O3-D4 component was mixed with 1 g of ZSM-5 molecular sieve raw powder and ground to obtain the catalyst of Comparative Example 4. The catalyst had a Pt content of 0.5%, an alumina content of 49.5%, and a molecular sieve content of 50% by mass.

[0071] [Comparative Example 5]

[0072] (1) A certain amount of aluminum nitrate was dissolved in a mixture of deionized water, ethanol and polyethylene oxide-polypropylene oxide-polyethylene oxide (P123), and after stirring for 30 minutes, 0.15 mol / L hydrochloric acid was added dropwise to obtain a precursor solution; the mass ratio of aluminum source in terms of Al2O3, P123, hydrochloric acid, ethanol and water was Al2O3: P123: hydrochloric acid: ethanol: H2O = 1: 2.0: 2.0: 15: 50;

[0073] (2) The precursor solution formed in step (1) was stirred at 50°C for 8 hours, placed in a tetrafluoroethylene-lined stainless steel kettle, sealed, transferred to a 100°C oven, and kept for 24 hours; then filtered and washed, the filter cake was placed in a 90°C oven for drying for 12 hours, and then air-treated at 750°C for 6 hours to obtain Al2O3-D5, and its corresponding specific surface area, pore volume and pentacoordinate Al 3+ Species (Al 3+ penta ) accounts for the total Al 3+ The proportions of species (indicated by X) are shown in Table 1 ;

[0074] (3) Pt loading by conventional impregnation method: 2 g Al2O3-D5 carrier was added to 100 g deionized water and stirred for 1.0 h. During the stirring process, 40 mL 0.5 mg Pt / mL H2PtCl6·6H2O solution, stirred for 3h, filtered and washed with 1.5L deionized water, the filter cake was dried in an oven at 100℃ for 12h, and then treated with air at 500℃ for 6h to obtain Pt / Al2O3-D5 component;

[0075] (4) 1 g of Pt / Al2O3-D5 component was mixed with 1 g of ZSM-5 molecular sieve raw powder and ground to obtain the catalyst of Comparative Example 5. The catalyst contained 0.5% Pt, 49.5% alumina and 50% molecular sieve by mass.

[0076] [Example 1]

[0077] (1) A certain amount of aluminum nitrate was dissolved in a mixture of deionized water, ethanol and polyethylene oxide-polypropylene oxide-polyethylene oxide (P123), and after stirring for 30 minutes, 0.15 mol / L hydrochloric acid was added dropwise to obtain a precursor solution; the mass ratio of aluminum source in terms of Al2O3, P123, hydrochloric acid, ethanol and water was Al2O3: P123: hydrochloric acid: ethanol: H2O = 1: 2.0: 2.0: 15: 50;

[0078] (2) The precursor solution formed in step (1) was stirred at 50°C for 8 hours, placed in a tetrafluoroethylene-lined stainless steel kettle, sealed, transferred to a 100°C oven, and kept for 24 hours; then filtered and washed, the filter cake was placed in a 90°C oven for drying for 12 hours, and then air-treated at 750°C for 6 hours to obtain Al2O3-S1, and its corresponding specific surface area, pore volume and pentacoordinate Al 3+ Species (Al 3+ penta ) accounts for the total Al 3+ The proportions of species (indicated by X) are shown in Table 1 ;

[0079] (3) Add 2g of Al2O3-S1 carrier to 100g of deionized water, stir for 1.0h, then slowly add hydrochloric acid to adjust the pH value to 3.5, and continue stirring for 2.0h. During the stirring process, add 40mL of 0.5mg Pt / mL H2PtCl6·6H2O solution, stirred for 3h, filtered and washed with 1.5L deionized water, the filter cake was dried in an oven at 100℃ for 12h, and then treated with air at 500℃ for 6h to obtain Pt / Al2O3-S1 component;

[0080] (4) 1 g of Pt / Al2O3-S1 component was mixed with 1 g of ZSM-5 molecular sieve raw powder and ground to obtain the catalyst of Example 1. The catalyst contained 0.5% Pt, 49.5% alumina and 50% molecular sieve by mass.

[0081] [Example 2]

[0082] (1) A certain amount of aluminum chloride was dissolved in a mixture of deionized water, ethanol and polyethylene oxide-polypropylene oxide-polyethylene oxide (P123), stirred for 30 minutes, and then 0.15 mol / L hydrochloric acid was added dropwise to obtain a precursor solution; the mass ratio of aluminum source in terms of Al2O3, P123, hydrochloric acid, nitric acid, ethanol and water was Al2O3: P123: hydrochloric acid: ethanol: H2O = 1: 1.0: 1.0: 15: 50;

[0083] (2) The precursor solution formed in step (1) was stirred at 30°C for 12 hours, placed in a tetrafluoroethylene-lined stainless steel kettle, sealed, transferred to a 90°C oven, and kept for 40 hours; then filtered and washed, the filter cake was placed in a 90°C oven for drying for 12 hours, and then air-treated at 750°C for 3 hours to obtain Al2O3-S2, and its corresponding specific surface area, pore volume and pentacoordinate Al 3+ Species (Al 3+ penta ) accounts for the total Al 3+ The proportions of species (indicated by X) are shown in Table 1 ;

[0084] (3) Add 2g of Al2O3-S2 carrier to 100g of deionized water, stir for 0.5h, then slowly add hydrochloric acid to adjust the pH value to 2.5, and continue stirring for 1.0h. During the stirring process, add 40mL of 0.5mg Pt / mL H2PtCl6·6H2O solution, stirred for 3h, filtered and washed with 1.5L deionized water, the filter cake was dried in an oven at 100℃ for 12h, and then treated with air at 500℃ for 6h to obtain Pt / Al2O3-S2 component;

[0085] (4) 1 g of Pt / Al2O3-S2 component was mixed with 1 g of ZSM-5 molecular sieve raw powder and ground to obtain the catalyst of Example 2. The catalyst contained 5% Pt, 45% alumina and 50% molecular sieve by mass.

[0086] [Example 3]

[0087] (1) A certain amount of aluminum chloride was dissolved in a mixture of deionized water, ethanol and polyoxypropylene-polyoxyethylene, and after stirring for 30 minutes, 0.25 mol / L nitric acid was added dropwise to obtain a precursor solution; the mass ratio of aluminum source in terms of Al2O3, P123, nitric acid, ethanol and water was Al2O3: polyoxypropylene-polyoxyethylene: nitric acid: ethanol: H2O = 1:1.5:1.0:15:20;

[0088] (2) The precursor solution formed in step (1) was stirred at 40°C for 4 hours, placed in a tetrafluoroethylene-lined stainless steel kettle, sealed, transferred to a 100°C oven, and kept for 30 hours; then filtered and washed, the filter cake was placed in a 90°C oven for drying for 12 hours, and then air-treated at 750°C for 8 hours to obtain Al2O3-S3, and its corresponding specific surface area, pore volume and pentacoordinate Al 3+ Species (Al 3+ penta ) accounts for the total Al 3+ The proportions of species (indicated by X) are shown in Table 1 ;

[0089] (3) Add 2g of Al2O3-S3 carrier to 100g of deionized water, stir for 0.1h, then slowly add hydrochloric acid to adjust the pH value to 3.0, and continue stirring for 2.0h. During the stirring process, add 20mL of 1.0mg Pt / mL H2PtCl6·6H2O solution, stirred for 3h, filtered and washed with 1.5L deionized water, the filter cake was dried in an oven at 100℃ for 12h, and then treated with air at 500℃ for 4h to obtain Pt / Al2O3-S3 component;

[0090] (4) 1 g of Pt / Al2O3-S3 component was mixed with 1 g of ZSM-5 molecular sieve raw powder and ground to obtain the catalyst of Example 3. The catalyst had a Pt content of 2.5%, an alumina content of 47.5%, and a molecular sieve content of 50% by mass.

[0091] [Example 4]

[0092] (1) A certain amount of aluminum sulfate was dissolved in a mixture of deionized water, ethanol, polyoxyethylene-polyoxybutylene and P123, and after stirring for 30 minutes, 0.25 mol / L nitric acid was added dropwise to obtain a precursor solution; the mass ratio of aluminum source in terms of Al2O3, polyoxyethylene-polyoxybutylene, P123, hydrochloric acid, ethanol and water was Al2O3: polyoxyethylene-polyoxybutylene: P123: nitric acid: ethanol: H2O = 1: 1.5: 1.0: 10: 50;

[0093] (2) The precursor solution formed in step (1) was stirred at 30°C for 10 hours, placed in a tetrafluoroethylene-lined stainless steel kettle, sealed, transferred to an 80°C oven, and kept for 30 hours; then filtered and washed, the filter cake was placed in a 90°C oven for drying for 12 hours, and then air-treated at 750°C for 8 hours to obtain Al2O3-S4, and its corresponding specific surface area, pore volume and pentacoordinate Al 3+ Species (Al 3+ penta ) accounts for the total Al 3+ The proportions of species (indicated by X) are shown in Table 1 ;

[0094] (3) Add 2g of Al2O3-S4 carrier to 100g of deionized water, stir for 1.0h, then slowly add hydrochloric acid to adjust the pH value to 3.5, and continue stirring for 2.0h. During the stirring process, add 20mL of 1.0mg Pt / mL H2PtCl6·6H2O solution, stirred for 3h, filtered and washed with 1.5L deionized water, the obtained filter cake was dried in an oven at 100℃ for 12h, and then treated with air at 500℃ for 4h to obtain Pt / Al2O3-S4 component;

[0095] (4) 1 g of Pt / Al2O3-S4 component was mixed with 1 g of ZSM-22 molecular sieve raw powder and ground to obtain the catalyst of Example 4. The catalyst contained 3% Pt, 47% alumina and 50% molecular sieve by mass.

[0096] [Example 5]

[0097] (1) A certain amount of aluminum sulfate was dissolved in a mixture of deionized water, ethanol, polyoxyethylene-polyoxybutylene and P123, and after stirring for 30 minutes, 0.25 mol / L nitric acid was added dropwise to obtain a precursor solution; the mass ratio of aluminum source in terms of Al2O3, polyoxyethylene-polyoxybutylene, P123, hydrochloric acid, nitric acid, ethanol and water was Al2O3: polyoxyethylene-polyoxybutylene: P123: nitric acid: ethanol: H2O = 1:1.5:1.0:15:45;

[0098] (2) The precursor solution formed in step (1) was stirred at 30°C for 8 hours, placed in a tetrafluoroethylene-lined stainless steel kettle, sealed, transferred to a 100°C oven, and kept for 36 hours; then filtered and washed, the filter cake was placed in a 90°C oven for drying for 12 hours, and then air-treated at 750°C for 8 hours to obtain Al2O3-S5, and its corresponding specific surface area, pore volume and pentacoordinate Al 3+ Species (Al 3+ penta ) accounts for the total Al 3+ The proportions of species (indicated by X) are shown in Table 1 ;

[0099] (3) Add 2g of Al2O3-S5 carrier to 100g of deionized water, stir for 0.6h, then slowly add hydrochloric acid to adjust the pH value to 2.5, and continue stirring for 1.0h. During the stirring process, add 20mL of 1.0mg Pt / mL H2PtCl6·6H2O solution, stirred for 3h, filtered and washed with 1.5L deionized water, the obtained filter cake was dried in an oven at 100℃ for 12h, and then treated with air at 500℃ for 4h to obtain Pt / Al2O3-S5 component;

[0100] (4) 1 g of Pt / Al2O3-S5 component was mixed with 1 g of ZSM-22 molecular sieve raw powder and ground to obtain the catalyst of Example 5. The catalyst had a Pt content of 7.5%, an alumina content of 42.5%, and a molecular sieve content of 50% by mass.

[0101] [Example 6]

[0102] (1) A certain amount of aluminum sulfate was dissolved in a mixture of deionized water, ethanol, polyoxyethylene-polyoxybutylene and P123, and after stirring for 30 minutes, 0.25 mol / L acetic acid was added dropwise to obtain a precursor solution; the mass ratio of aluminum source in terms of Al2O3, polyoxyethylene-polyoxybutylene, P123, acetic acid, ethanol and water was Al2O3: polyoxyethylene-polyoxybutylene: P123: acetic acid: ethanol: H2O = 1:2.0:1.0:11:20;

[0103] (2) The precursor solution formed in step (1) was stirred at 30°C for 10 hours, placed in a tetrafluoroethylene-lined stainless steel kettle, sealed, transferred to a 90°C oven, and kept for 40 hours; then filtered and washed, the filter cake was placed in a 90°C oven for drying for 12 hours, and then air-treated at 750°C for 8 hours to obtain Al2O3-S6, and its corresponding specific surface area, pore volume and pentacoordinate Al 3+ Species (Al 3+ penta ) accounts for the total Al 3+ The proportions of species (indicated by X) are shown in Table 1 ;

[0104] (3) Add 2g of Al2O3-S6 carrier to 100g of deionized water, stir for 1.0h, then slowly add hydrochloric acid to adjust the pH value to 1.5, and continue stirring for 1.0h. During the stirring process, add 400mL of 1.0mg Pt / mL H2PtCl6·6H2O solution, stirred for 3h, filtered and washed with 1.5L deionized water, the filter cake was dried in an oven at 100℃ for 12h, and then treated with air at 500℃ for 4h to obtain Pt / Al2O3-S6 component;

[0105] (4) 1 g of Pt / Al2O3-S6 component was mixed with 1 g of ZSM-11 molecular sieve raw powder and ground to obtain the catalyst of Example 6. The catalyst contained 10% Pt, 40% alumina and 50% molecular sieve by mass.

[0106] [Example 7]

[0107] (1) A certain amount of aluminum isopropoxide was dissolved in a mixture of deionized water, ethanol, and P123, and after stirring for 30 minutes, 0.25 mol / L phosphoric acid was added dropwise to obtain a precursor solution; the mass ratio of aluminum source in terms of Al2O3, polyoxyethylene-polyoxybutylene, P123, phosphoric acid, ethanol, and water was Al2O3: P123: phosphoric acid: ethanol: H2O = 1: 1.5: 1.0: 10: 50;

[0108] (2) The precursor solution formed in step (1) was stirred at 30°C for 12 hours, placed in a tetrafluoroethylene-lined stainless steel kettle, sealed, transferred to a 90°C oven, and kept for 24 hours; then filtered and washed, the filter cake was placed in a 90°C oven for drying for 12 hours, and then air-treated at 750°C for 8 hours to obtain Al2O3-S7, and its corresponding specific surface area, pore volume and pentacoordinate Al 3+ Species (Al 3+ penta ) accounts for the total Al 3+ The proportions of species (indicated by X) are shown in Table 1 ;

[0109] (3) Add 2g of Al2O3-S7 carrier to 100g of deionized water, stir for 1.0h, then slowly add hydrochloric acid to adjust the pH value to 3.5, and continue stirring for 2.0h. During the stirring process, add 0.4mL of 1.0mg Pt / mL H2PtCl6·6H2O solution, stirred for 3h, filtered and washed with 1.5L deionized water, the filter cake was dried in an oven at 100℃ for 12h, and then treated with air at 500℃ for 4h to obtain Pt / Al2O3-S7 component;

[0110] (4) 1 g of Pt / Al2O3-S7 component was mixed with 1 g of ZSM-11 molecular sieve raw powder and ground to obtain the catalyst of Example 7. The catalyst contained 0.01% Pt, 44.99% alumina and 50% molecular sieve by mass.

[0111] [Example 8]

[0112] (1) A certain amount of aluminum sol was dissolved in a mixture of deionized water, ethanol and polyethylene oxide-polypropylene oxide-polyethylene oxide (P123), stirred for 30 minutes, and then 0.15 mol / L nitric acid was added dropwise to obtain a precursor solution; the mass ratio of aluminum source in terms of Al2O3, P123, hydrochloric acid, ethanol and water was Al2O3: P123: hydrochloric acid: ethanol: H2O = 1: 0.5: 0.5: 15: 50;

[0113] (2) The precursor solution formed in step (1) was stirred at 50°C for 8 hours, placed in a tetrafluoroethylene-lined stainless steel kettle, sealed, transferred to a 100°C oven, and kept for 24 hours; then filtered and washed, the filter cake was placed in a 90°C oven for drying for 12 hours, and then air-treated at 750°C for 6 hours to obtain Al2O3-S8, and its corresponding specific surface area, pore volume and pentacoordinate Al 3+ Species (Al 3+ penta ) accounts for the total Al 3+ The proportions of species (indicated by X) are shown in Table 1 ;

[0114] (3) Add 2g of Al2O3-S8 carrier to 100g of deionized water, stir for 1.0h, then slowly add hydrochloric acid to adjust the pH value to 3.5, and continue stirring for 2.0h. During the stirring process, add 40mL of 0.5mg Pt / mL H2PtCl6·6H2O solution, stirred for 3h, filtered and washed with 1.5L deionized water, the filter cake was dried in an oven at 100℃ for 12h, and then treated with air at 500℃ for 6h to obtain Pt / Al2O3-S8 component;

[0115] (4) 1 g of Pt / Al2O3-S8 component was mixed with 1 g of ZSM-5 molecular sieve raw powder and ground to obtain the catalyst of Example 8. The catalyst contained 0.5% Pt, 49.5% alumina and 50% molecular sieve by mass.

[0116] [Example 9]

[0117] The catalysts prepared in Examples 1-8 and Comparative Examples 1-5 were pressed into tablets, sieved through 20-40 mesh, and 0.3 g of the catalyst was placed in a fixed bed reactor. The temperature was raised from room temperature to 450°C at a rate of 10°C / min under a hydrogen atmosphere. After reduction for 2 hours, the catalyst was cooled to the reaction temperature and then evaluated. The catalyst evaluation conditions were as follows: temperature was 260°C, pressure was 1.0 MPa, the molar ratio of hydrogen to n-hexane was 6.0, and the mass space velocity of n-hexane was 4.5 h / min. -1 The evaluation results of each catalyst are shown in Table 3.

[0118] Table 1 Specific surface area (S) of alumina obtained in each example BET ), pore volume (V), and pentacoordinated Al 3+ Species (Al 3+ penta ) accounts for the total Al 3+ Proportion of species (X)

[0119] Alumina <![CDATA[S BET (m 2 / g)]]> V(mL / g) X(％) Comparative Example 1 70.1 0.15 12.0 Comparative Example 2 109.2 0.23 19.6 Comparative Example 3 122.1 0.25 25.3 Comparative Example 4 99.8 0.20 19.0 Comparative Example 5 204.1 0.21 11.0 Example 1 334.1 0.61 66.9 Example 2 274.9 0.55 59.0 Example 3 344.9 0.60 65.7 Example 4 224.9 0.49 65.6 Example 5 344.8 0.66 67.4 Example 6 304.1 0.56 63.1 Example 7 348.2 0.69 68.9 Example 8 294.1 0.41 45.6

[0120] Table 2 The size of Pt crystals in the catalysts obtained in each example

[0121]

[0122]

[0123] Table 3 Evaluation results of the catalysts obtained in each example

[0124] catalyst Conversion rate (%) Isohexane selectivity (%) Yield of isohexane (%) Comparative Example 1 28.70 67.90 19.49 Comparative Example 2 33.10 73.90 24.46 Comparative Example 3 40.30 77.10 31.07 Comparative Example 4 35.70 70.20 25.06 Comparative Example 5 55.00 80.10 44.06 Example 1 77.70 97.60 75.84 Example 2 70.60 88.90 62.76 Example 3 72.10 97.80 70.51 Example 4 73.90 95.90 70.87 Example 5 78.90 99.10 78.19 Example 6 82.10 98.10 80.54 Example 7 65.90 95.10 62.67 Example 8 70.70 87.60 61.93

[0125] The above describes the specific implementation of the present invention in detail, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the various technical features being combined in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A C4-C8 alkane isomerization catalyst, comprising an active metal Pt, an alumina component and a molecular sieve carrier; the alumina component has a penta-coordinated Al 3+ Species accounted for the total Al 3+ 30% to 70% of the species, preferably 50% to 70%.

2. The catalyst according to claim 1, characterized in that The specific surface area of ​​the aluminum oxide is 150.0 to 350.0 m 2 / g, preferably 250.0 to 350.0 m 2 / g; And / or, the pore volume of the alumina is 0.30 to 0.70 mL / g, preferably 0.45 to 0.70 mL / g.

3. The catalyst according to claim 1, characterized in that The molecular sieve is at least one selected from ZSM-5, ZSM-11, ZSM-22, ZSM-35, Beta, MOR, and Y; preferably at least one selected from ZSM-5, ZSM-11, and ZSM-22.

4. The catalyst according to claim 1, characterized in that In the catalyst, the mass ratio of the molecular sieve to the alumina component is 9:1 to 1:9, preferably 3:1 to 1:3, and more preferably 1:1 to 1:0.5; And / or, based on the mass of the catalyst, the content of active metal Pt is 0.01% to 10.0%.

5. The catalyst according to claim 1, characterized in that In the catalyst, the average particle size of the active metal Pt crystal particles is 0.20 nm to 1.00 nm, preferably 0.20 nm to 0.50 nm.

6. A method for preparing a catalyst according to any one of claims 1 to 5, comprising the following steps: (1) mixing an aluminum source, a high molecular weight polymer, an inorganic acid, an alcohol and water to obtain a precursor solution; (2) The precursor solution is subjected to heat treatment, modification treatment, and calcination to obtain aluminum oxide; (3) adding the Pt precursor solution dropwise to the suspension of alumina obtained in step (2) to react and obtain active Pt / Al2O3; (4) Mixing the active Pt / Al2O3 obtained in step (3) with the molecular sieve to obtain the alkane isomerization catalyst.

7. The preparation method according to claim 6, characterized in that: In step (1), the aluminum source is calculated as Al2O3, the high molecular weight polymer, and the inorganic acid are calculated as H + The mass ratio of alcohol and water is, that is, Al2O3: polymer: inorganic acid: alcohol: H2O = 1: 0.5~2.0: 0.5~2.0: 4.5~15: 20~50.

8. The preparation method according to claim 6, characterized in that: In step (1), the high molecular polymer is selected from one or more of polyoxyethylene, polyoxypropylene, polyoxybutylene, polyoxypropylene-polyoxyethylene, polyoxyethylene-polyoxybutylene, polyoxypropylene-polyoxybutylene, polyethylene oxide, polypropylene oxide, polyethylene oxide-polyoxypropylene oxide-polyethylene oxide, preferably one or more of polyoxypropylene-polyoxyethylene, polyoxyethylene-polyoxybutylene, polyethylene oxide-polyoxypropylene oxide-polyethylene oxide; and / or, the inorganic acid is selected from at least one of hydrochloric acid, nitric acid, acetic acid, sulfuric acid, phosphoric acid and carbonic acid, preferably at least one of nitric acid and hydrochloric acid; And / or, the alcohol is selected from at least one of methanol, ethanol, ethylene glycol, propanol and glycerol, preferably ethanol.

9. The preparation method according to claim 6, characterized in that: In step (2), the heat treatment is carried out under stirring, the heat treatment temperature is 30 to 90° C., preferably 30 to 50° C., and the heat treatment time is 0.5 h to 24 h, preferably 4 h to 12 h; And / or, the modification treatment is carried out by heating in a closed environment, the temperature of the modification treatment is 70 to 150° C., preferably 70 to 100° C., and the time of the modification treatment is 5 h to 60 h, preferably 24 h to 40 h; and / or, the temperature of the modification treatment is 20 to 80° C. higher than the temperature of the heat treatment; And / or, the calcination conditions are as follows: the calcination temperature is 350-750° C., and the calcination time is 6-12 hours.

10. The preparation method according to claim 6, characterized in that: In step (3), the Pt concentration in the Pt precursor solution is 0.001 mg Pt / mL~2.50mg Pt / mL, preferably 0.1mg Pt / mL~1.5mg Pt / mL; And / or, in step (3), the reaction time is 0.5 to 10.5 h; And / or, in step (4), the mass ratio of the active Pt / Al2O3 to the molecular sieve is 1:9 to 9:1, preferably 3:7 to 6:

4.

11. The preparation method according to claim 6, characterized in that: The preparation process of the aluminum oxide suspension is as follows: firstly, aluminum oxide is mixed with water, stirred for 0.1 to 1.0 h, then hydrochloric acid is slowly added dropwise to adjust the pH value to 0.5 to 3.5, and stirring is continued for 0.5 to 2.0 h.

12. Use of the catalyst according to any one of claims 1 to 5 in catalyzing the isomerization reaction of C4-C8 alkanes.

13. The use according to claim 12, characterized in that: The reaction conditions are as follows: reaction temperature is 180-405°C, reaction pressure is 1.0-3.0 MPa, molar ratio of hydrogen to alkane is 1.0-7.0, mass space velocity of alkane is 1.5-9.5 h -1 .

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