A c4-c8 alkane isomerization catalyst, its preparation method and application

Abstract

The application discloses a C4-C8 alkane isomerization catalyst and a preparation method and application thereof. The catalyst comprises an active metal Pt, an alumina component and a molecular sieve carrier; five-coordinated Al 3+ species accounts for 30% to 70% of total Al 3+ species. The catalyst is used for C4-C8 n-alkane isomerization hydrogenation reaction, and has high isomer product selectivity and yield.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of C4-C8 alkane isomerization reaction, and particularly relates to a C4-C8 alkane isomerization catalyst as well as a preparation method and application thereof. BACKGROUND

[0002] Hydroisomerization of C4-C8 light alkanes can produce clean isomerate 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 a medium-temperature type metal / zeolite bifunctional catalyst system. Common active metals are generally noble metals such as Pt, Pd, Ir, which mainly provide hydrogenation-dehydrogenation function; and the zeolite system mainly provides acid sites and pore shape-selective function. According to the unique pore topology and physicochemical properties of the zeolite, excellent catalytic performance can be exhibited in specific alkane isomerization reactions. Recently, the de Jong research group placed Pt on alumina, regulated the nanoscale intimacy between the metal center and the acid center of the zeolite, and the catalyst exhibited 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). In the reaction process, the Pt / Al2O3 component mainly provides hydrogenation-dehydrogenation active sites, and the physicochemical properties of the alumina carrier (including specific surface area, pore volume, coordination state of Al, etc.) will affect the dispersion of the Pt active center and the interaction form between Pt and alumina, and finally affect the isomerization reaction activity and the selectivity of the target product. Based on this consideration, designing a suitable alumina carrier is an effective strategy to optimize the isomerization reaction process.

[0003] CN104492407A used NaAlO2-Al2(SO4)3 as raw material, and prepared a large pore volume (1.8-2.2 mL / g) alumina by oil ammonia column method and using surfactant containing ammonia water forming strategy. CN103172097A synthesized an alumina carrier by nucleation and crystallization isolation method, with a pore volume of 0.5-1.2 mL / g and a pore size of 10-30 nm; CN1114290A and CN1068975A used aluminum salt or aluminate salt precipitation-peptization, and then formed a large pore volume of spherical alumina by oil column method; CN113492003A disclosed a preparation method of an alumina carrier with large pore and high specific surface area, which mixed the mixed acid of aluminum source, hydrochloric acid and citric acid, and then aged, dried and calcined under the action of pore expanding agent and coagulant to obtain the alumina carrier. Gong Jinlong research group prepared an alumina carrier by using isopropyl alcohol aluminum as aluminum source and under the action of Pluronic P123 and nitric acid by steam-induced self-assembly strategy. The above alumina contains rich pentacoordinate Al 3 + penta species, and it is pointed out that the content of Al 3+ penta species can significantly change the state of Pt active center, and the obtained catalyst exhibits excellent stability in propane dehydrogenation reaction (The role of pentacoordinate Al 3+ sites of Pt / Al2O3catalysts in propane dehydrogenation, Fundamental Research (2022)). Bao Xinhe research group synthesized an alumina carrier containing rich pentacoordinate Al 3+ penta species by Ga modification strategy, which exhibited excellent alkane dehydrogenation activity after loading Pt (The effect of Al 3+ coordination structure on the propane dehydrogenation activity of Pt / Ga / Al2O3catalysts. Journal of Energy Chemistry 41 (2020) 93-99). However, there is still a lack of effective means to prepare an alumina carrier with high surface area, large pore and rich Al 3+ penta species by one-step method. In the process of isomerization reaction, Al 3+ pentaThe regulation of species on reactivity and selectivity has not been involved. SUMMARY

[0004] To solve the above problems, the application provides a C4-C8 alkane isomerization catalyst, a preparation method and application thereof.

[0005] The first aspect of the application provides a C4-C8 alkane isomerization catalyst, which comprises active metal Pt, an alumina component and a molecular sieve carrier; the five-coordinated Al 3+ species in the alumina component accounts for 30% to 70%, preferably 50% to 70% of the total Al 3+ penta species. 3+

[0006] Further, 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] Further, the pore volume of the alumina is 0.30 to 0.70 mL / g, preferably 0.45 to 0.70 mL / g.

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

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

[0010] Further, 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 further preferably 1:1 to 1:0.5.

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

[0012] Further, in the catalyst, the average particle size of the active metal Pt crystal grains 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-mentioned catalyst, comprising the following steps:

[0014] (1) Aluminum source, polymer, inorganic acid, alcohol and water are mixed to obtain precursor solution;

[0015] (2) The precursor liquid is heat-treated, modified, and calcined to obtain alumina;

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

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

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

[0019] Further, 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 boehmite, preferably one or more of aluminum chloride, aluminum sulfate, aluminum nitrate, aluminum isopropoxide, or aluminum sol.

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

[0021] Further, 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] Further, in step (1), the alcohol is selected from at least one of methanol, ethanol, ethylene glycol, propanol, and glycerol, preferably ethanol.

[0023] Further, in step (2), the heat treatment is carried out under stirring, the temperature of the heat treatment 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] Further, in step (2), after the heat treatment, the modification treatment is carried out under a closed environment. The temperature of the modification treatment is 70-150℃, preferably 70-100℃, and the time of the modification treatment is 5h-60h, preferably 24h-40h.

[0025] Further, the temperature of the modification treatment is 20-80v higher than the temperature of the heat treatment.

[0026] Further, in step (2), the calcination conditions are as follows: the calcination temperature is 350-750℃, preferably 500-750℃; and the calcination time is 4-12h, preferably 4-8h.

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

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

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

[0030] Further, in step (3), the reaction time is 0.5-10.5h. After the reaction, the active Pt / Al2O3 is obtained through the conventional operations of filtration, washing, drying and calcination. The drying conditions are as follows: the temperature is 40-120℃, and the time is 2-15h; and the calcination conditions are as follows: the temperature is 350-500℃, and the time is 2-15h.

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

[0032] Further, in step (4), the mixing is physical mixing, and the mixing methods include grinding, ball milling and the like.

[0033] The third aspect of the present application also provides the use of the above-mentioned catalyst in the catalytic isomerization reaction of alkanes.

[0034] Further, the alkanes are at least one of the n-alkanes with the number of C atoms being 4-8 (such as at least one of n-pentane, n-hexane, n-heptane and n-octane).

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

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

[0037] 1. The present application provides a new C4-C8 alkane isomerization catalyst, comprising active metal, alumina component and molecular sieve, wherein the proportion of five-coordinated Al 3+ species (Al 3+ penta ) in the total Al 3+ species in the alumina component is X, the value of X is 30%-70%, the specific surface area is 150.0-350.0m 2 / g, and the pore volume is 0.30-0.70mL / g. The catalyst is applied to C4-C8 normal alkane isomerization reaction in the presence of hydrogen, is conducive to the generation of isomerization products, and has high isomer product selectivity and yield.

[0038] 2. One aspect of the present application is based on the specific modification properties of high molecular polymers, by changing the molecular composition, modification liquid ratio and subsequent treatment conditions, to prepare a high specific surface area alumina carrier rich in Al 3+ penta species; another aspect is to load Pt active metal on the above alumina carrier by electrostatic adsorption strategy, and then physically mix with molecular sieve, and finally obtain the catalyst with higher isomer product selectivity and yield in the process of C4-C8 normal alkane isomerization reaction in the presence of hydrogen. DETAILED DESCRIPTION

[0039] In order to more clearly illustrate the technical scheme of the present application, the following specific embodiment is listed. However, those skilled in the art will easily understand that the content described in the examples is only used to illustrate the present application, and should not and will not limit the present application described in detail in the claims.

[0040] In the present application, the specific surface area and pore volume of the sample are tested by nitrogen physical adsorption on Micromeritics ASAP 2020M. Before testing, the sample is treated in vacuum at 350℃ for 4h, and the specific surface area is calculated by BET multipoint method in the relative pressure range of 0.05-0.25, and the pore volume and pore diameter are obtained by Saito-Foley method.

[0041] In the present application, the five-coordinated Al 3+ species (Al3+ penta )Total Al 3+ The proportion of the species (denoted by X) is determined using 27 The Al MAS NMR nuclear magnetic experiment is determined using a Bruker Avance III-600 with a 156.4MHz Larmor frequency, and a Bruker 4mm HXY MAS NMR probe with a magic angle spinning (MAS) frequency of 12kHZ. 27 The chemical shift of Al is analyzed using an aqueous solution of aluminum nitrate with a concentration of 1mol / L as an external standard. Before testing, the alumina sample is subjected to oven drying treatment to fully dehydrate.

[0042] In the present application, the related 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 application, the related 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 application, the related 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 application, the reaction product is analyzed using an Agilent 7890B gas chromatograph.

[0046] In the present application, the calculation formulas of 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) x 100%;

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

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

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

[0051] Comparative Example 1

[0052] (1) Dissolve a certain amount of aluminum nitrate in a mixture of deionized water and ethanol, stir for 30 min, and then add 0.15 mol / L hydrochloric acid to obtain a precursor solution; the aluminum source is calculated as Al2O3, and the mass ratio of hydrochloric acid, ethanol and water is 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 stainless steel autoclave lined with tetrafluoroethylene, sealed, and then transferred to a 100°C oven for 24 hours. After filtration and washing, the filter cake was dried in a 90°C oven for 12 hours, followed by air treatment at 750°C for 6 hours to obtain Al2O3-D1, whose corresponding specific surface area, pore volume, and five-coordinate Al 3+ Species (Al) 3+ penta ) occupying the total Al 3+ The proportion of species (denoted by X) is shown in Table 1;

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

[0055] (4) Mix 1g of Pt / Al2O3-D1 component with 1g of ZSM-5 molecular sieve powder and grind to obtain the catalyst of Comparative Example 1. By mass, the catalyst contains 0.5% Pt, 49.5% alumina, and 50% molecular sieve.

[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 min to obtain a precursor solution; the mass ratio of aluminum source (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 stainless steel autoclave lined with tetrafluoroethylene, sealed, and then transferred to a 100°C oven for 24 hours. After filtration and washing, the filter cake was dried in a 90°C oven for 12 hours, followed by air treatment at 750°C for 6 hours to obtain Al2O3-D2, whose corresponding specific surface area, pore volume, and five-coordinate Al 3+ Species (Al) 3+ penta ) occupying the total Al 3+ The proportion of species (denoted by X) is shown in Table 1;

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

[0060] (4) Mix 1g of Pt / Al2O3-D2 component with 1g of ZSM-5 molecular sieve powder and grind to obtain catalyst of Comparative Example 2. By mass, the catalyst contains 0.5% Pt, 49.5% alumina, and 50% molecular sieve.

[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). After stirring for 30 min, 0.15 mol / L hydrochloric acid was added dropwise to obtain a precursor solution. The mass ratio of aluminum source (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 stainless steel autoclave lined with tetrafluoroethylene, sealed, and then transferred to an oven at 100°C for 24 hours. After filtration and washing, the filter cake was dried in an oven at 90°C for 12 hours, followed by air treatment at 750°C for 6 hours to obtain Al2O3-D3, whose corresponding specific surface area, pore volume, and five-coordinate Al 3+ Species (Al) 3+ penta ) occupying the total Al 3+ The proportion of species (denoted by X) is shown in Table 1;

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

[0065] (4) Mix 1g of Pt / Al2O3-D3 component with 1g of ZSM-5 molecular sieve powder and grind to obtain catalyst of Comparative Example 3. By mass, the catalyst contains 0.5% Pt, 49.5% alumina, and 50% molecular sieve.

[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). After stirring for 30 min, 0.15 mol / L hydrochloric acid was added dropwise to obtain a precursor solution. The mass ratio of aluminum source (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 stainless steel autoclave lined with tetrafluoroethylene, sealed, and then transferred to an oven at 170°C for 24 hours. After filtration and washing, the filter cake was dried in an oven at 90°C for 12 hours, followed by air treatment at 750°C for 6 hours to obtain Al2O3-D4, whose corresponding specific surface area, pore volume, and five-coordinate Al 3+ Species (Al) 3+ penta ) occupying the total Al 3+ The proportion of species (denoted by X) is shown in Table 1;

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

[0070] (4) Mix 1g of Pt / Al2O3-D4 component with 1g of ZSM-5 molecular sieve powder and grind to obtain the catalyst of Comparative Example 4. By mass, the catalyst contains 0.5% Pt, 49.5% alumina, and 50% molecular sieve.

[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). After stirring for 30 min, 0.15 mol / L hydrochloric acid was added dropwise to obtain a precursor solution. The mass ratio of aluminum source (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 stainless steel autoclave lined with tetrafluoroethylene, sealed, and then transferred to an oven at 100°C for 24 hours. After filtration and washing, the filter cake was dried in an oven at 90°C for 12 hours, followed by air treatment at 750°C for 6 hours to obtain Al2O3-D5, whose corresponding specific surface area, pore volume, and five-coordinate Al 3+ Species (Al) 3+ penta ) occupying the total Al 3+ The proportion of species (denoted by X) is shown in Table 1;

[0074] (3) Loading Pt using the conventional impregnation method: Add 2g of Al2O3-D5 support to 100g of deionized water and stir for 1.0h. During stirring, add 40mL of 0.5mg Pt dropwise. Pt The solution of H2PtCl6·6H2O was stirred for 3 hours, filtered, and washed with 1.5 L of deionized water. The resulting filter cake was dried in an oven at 100 °C for 12 hours and then air-treated at 500 °C for 6 hours to obtain the Pt / Al2O3-D5 component.

[0075] (4) Mix 1g of Pt / Al2O3-D5 component with 1g of ZSM-5 molecular sieve powder and grind to obtain the catalyst of Comparative Example 5. By mass, the catalyst contains 0.5% Pt, 49.5% alumina, and 50% molecular sieve.

[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). After stirring for 30 min, 0.15 mol / L hydrochloric acid was added dropwise to obtain a precursor solution. The mass ratio of aluminum source (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 stainless steel autoclave lined with PTFE, sealed, and then transferred to a 100°C oven for 24 hours. After filtration and washing, the filter cake was dried in a 90°C oven for 12 hours, followed by air treatment at 750°C for 6 hours to obtain Al2O3-S1, whose corresponding specific surface area, pore volume, and five-coordinate Al 3+ Species (Al) 3+ penta ) occupying the total Al 3+ The proportion of species (denoted by X) is shown in Table 1;

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

[0080] (4) Mix 1g of Pt / Al2O3-S1 component with 1g of ZSM-5 molecular sieve powder and grind to obtain the catalyst of Example 1. By mass, the catalyst contains 0.5% Pt, 49.5% alumina, and 50% molecular sieve.

[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). After stirring for 30 min, 0.15 mol / L hydrochloric acid was added dropwise to obtain a precursor solution. The mass ratio of aluminum source (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 stainless steel autoclave lined with tetrafluoroethylene, sealed, and then transferred to a 90°C oven for 40 hours. After filtration and washing, the filter cake was dried in a 90°C oven for 12 hours, followed by air treatment at 750°C for 3 hours to obtain Al2O3-S2, whose corresponding specific surface area, pore volume, and five-coordinate Al 3+ Species (Al) 3+ penta ) occupying the total Al 3+ The proportion of species (denoted by X) is shown in Table 1;

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

[0085] (4) Mix 1g of Pt / Al2O3-S2 component with 1g of ZSM-5 molecular sieve powder, grind, and obtain the catalyst of Example 2. By mass, the catalyst contains 5% Pt, 45% alumina, and 50% molecular sieve.

[0086]

Example 3

[0087] (1) A certain amount of aluminum chloride was dissolved in a mixture of deionized water, ethanol and polyoxypropylene-polyoxyethylene, stirred for 30 min, and then 0.25 mol / L nitric acid was added dropwise to obtain a precursor solution; the aluminum source was calculated as Al2O3, and the mass ratio of 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 stainless steel autoclave lined with PTFE, sealed, and then transferred to a 100°C oven for 30 hours. After filtration and washing, the filter cake was dried in a 90°C oven for 12 hours, followed by air treatment at 750°C for 8 hours to obtain Al2O3-S3, whose corresponding specific surface area, pore volume, and five-coordinate Al 3+ Species (Al) 3+ penta ) occupying the total Al 3+ The proportion of species (denoted by X) is shown in Table 1;

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

[0090] (4) Mix 1g of Pt / Al2O3-S3 component with 1g of ZSM-5 molecular sieve powder and grind to obtain the catalyst of Example 3. By mass, the catalyst contains 2.5% Pt, 47.5% alumina, and 50% molecular sieve.

[0091]

Example 4

[0092] (1) A certain amount of aluminum sulfate was dissolved in a mixture of deionized water, ethanol, polyoxyethylene-polyoxybutene and P123. After stirring for 30 min, 0.25 mol / L nitric acid was added dropwise to obtain a precursor solution. The mass ratio of aluminum source (Al2O3), polyoxyethylene-polyoxybutene, P123, hydrochloric acid, ethanol and water was Al2O3:polyoxyethylene-polyoxybutene: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 stainless steel autoclave lined with tetrafluoroethylene, sealed, and then transferred to an 80°C oven for 30 hours. After filtration and washing, the filter cake was dried in a 90°C oven for 12 hours, followed by air treatment at 750°C for 8 hours to obtain Al2O3-S4, whose corresponding specific surface area, pore volume, and five-coordinate Al 3+ Species (Al) 3+ penta ) occupying the total Al 3+ The proportion of species (denoted by X) is shown in Table 1;

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

[0095] (4) 1 g of the Pt / Al2O3-S5 component was mixed with 1 g of the ZSM-22 molecular sieve raw powder, and ground to obtain the catalyst of Example 4. The content of Pt in the catalyst was 3% by mass, the content of alumina was 47% by mass, and the content of the molecular sieve was 50% by mass.

[0096] [Example 5]

[0097] (1) A certain amount of aluminum sulfate was dissolved in a mixed solution of deionized water, ethanol, polyoxyethylene-polyoxybutylene, and P 123, and after stirring for 30 min, 0.25 mol / L nitric acid was added dropwise to obtain a precursor solution; the mass ratio of the aluminum source (calculated as Al2O3), polyoxyethylene-polyoxybutylene, P123, hydrochloric acid, nitric acid, ethanol, and water was Al2O3: polyoxyethylene-polyoxybutylene: P123: hydrochloric acid: nitric acid: ethanol: H2O = 1: 1.5: 1.0: 15: 45;

[0098] (2) The precursor solution formed in step (1) was continuously stirred at 30°C for 8 h, placed in a tetrafluoroethylene-lined stainless steel kettle, sealed, and then transferred to a 100°C oven for 36 h; then filtered and washed, the filter cake was placed in a 90°C oven for drying for 12 h, and then air-treated at 750°C for 8 h to obtain Al2O3-S5, the corresponding specific surface area, pore volume, and five-coordinated Al 3+ species (Al 3+ penta ) accounted for a proportion (denoted as X) of the total Al 3+ species, as shown in Table 1;

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

[0100] (4) 1 g of the Pt / Al2O3-S5 component was mixed with 1 g of the ZSM-22 molecular sieve raw powder, and ground to obtain the catalyst of Example 4. The content of Pt in the catalyst was 3% by mass, the content of alumina was 47% by mass, and the content of the molecular sieve was 50% by mass.

[0101] [Example 5]

[0102] (1) A certain amount of aluminum sulfate was dissolved in a mixture of deionized water, ethanol, polyoxyethylene-polyoxybutene and P123. After stirring for 30 min, 0.25 mol / L acetic acid was added dropwise to obtain a precursor solution. The mass ratio of aluminum source (calculated as Al2O3), polyoxyethylene-polyoxybutene, P123, acetic acid, ethanol and water was Al2O3:polyoxyethylene-polyoxybutene: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 h, placed in a stainless steel autoclave lined with tetrafluoroethylene, sealed, and then transferred to a 90°C oven for 40 h. After filtration and washing, the filter cake was dried in a 90°C oven for 12 h, and then air-treated at 750°C for 8 h to obtain Al2O3-S6, whose corresponding specific surface area, pore volume, and five-coordinate Al 3+ Species (Al) 3+ penta ) occupying the total Al 3+ The proportion of species (denoted by X) is shown in Table 1;

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

[0105] (4) Mix 1g of Pt / Al2O3-S6 component with 1g of ZSM-11 molecular sieve powder and grind to obtain the catalyst of Example 6. By mass, the catalyst contains 10% Pt, 40% alumina, and 50% molecular sieve.

[0106]

Example 7

[0107] (1) A certain amount of aluminum isopropoxide was dissolved in a mixture of deionized water, ethanol, and P123. After stirring for 30 min, 0.25 mol / L phosphoric acid was added dropwise to obtain a precursor solution. The mass ratio of aluminum source (calculated as Al2O3), polyoxyethylene-polyoxybutene, 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 stainless steel autoclave lined with tetrafluoroethylene, sealed, and then transferred to a 90°C oven for 24 hours. After filtration and washing, the filter cake was dried in a 90°C oven for 12 hours, followed by air treatment at 750°C for 8 hours to obtain Al2O3-S7, whose corresponding specific surface area, pore volume, and five-coordinate Al 3+ Species (Al) 3+ penta ) occupying the total Al 3+ The proportion of species (denoted by X) is shown in Table 1;

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

[0110] (4) Mix 1g of Pt / Al2O3-S7 component with 1g of ZSM-11 molecular sieve powder and grind to obtain the catalyst of Example 7. By mass, the catalyst contains 0.01% Pt, 44.99% alumina, and 50% molecular sieve.

[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 min, and then 0.15 mol / L nitric acid was added dropwise to obtain a precursor solution; the mass ratio of aluminum source (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 stainless steel autoclave lined with tetrafluoroethylene, sealed, and then transferred to a 100°C oven for 24 hours. After filtration and washing, the filter cake was dried in a 90°C oven for 12 hours, followed by air treatment at 750°C for 6 hours to obtain Al2O3-S8, whose corresponding specific surface area, pore volume, and five-coordinate Al 3+ Species (Al) 3+ penta ) occupying the total Al 3+ The proportion of species (denoted by X) is shown in Table 1;

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

[0115] (4) Mix 1g of Pt / Al2O3-S8 component with 1g of ZSM-5 molecular sieve powder and grind to obtain the catalyst of Example 8. By mass, the catalyst contains 0.5% Pt, 49.5% alumina, and 50% molecular sieve.

[0116]

Example 9

[0117] The catalysts prepared in Examples 1-8 and Comparative Examples 1-5 were pressed into tablets, sieved through a 20-40 mesh, and 0.3 g of catalyst was placed in a fixed-bed reactor. Under a hydrogen atmosphere, the temperature was increased from room temperature to 450°C at a rate of 10°C / min. After reduction for 2 h, the temperature was lowered to the reaction temperature for catalyst evaluation. The catalyst evaluation conditions were as follows: temperature 260°C, pressure 1.0 MPa, hydrogen to hexane molar ratio 6.0, and hexane mass hourly space velocity (WHSV) 4.5 h⁻¹. -1 The evaluation results for 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 five-coordinate Al 3+ Species (Al) 3+ penta ) occupying the total Al 3+ Species ratio (X)

[0119] Alumina 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 shows the Pt grain size in the catalysts obtained in each example.

[0121]

[0122]

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

[0124] Catalyst Conversion (%) i-Hexane selectivity (%) i-Hexane yield (%) 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 specific embodiments of the present application are described above in detail, but the present application is not limited to this. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including that various technical features are combined in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the present application and belong to the protection scope of the present application.

Claims

1. A C4-C8 alkane isomerization catalyst, said catalyst comprising an active metal Pt, an alumina component, and a molecular sieve support; wherein the alumina component contains five-coordinated Al. 3+ Species account for a total of Al 3+ The alumina comprises 30% to 70% of the species, and has a specific surface area of ​​150.0 to 350.0 m². 2 / g, the pore volume of the alumina is 0.30~0.70 mL / g, and the average particle size of the active metal Pt crystals in the catalyst is 0.20 nm~1.00 nm.

2. The catalyst according to claim 1, characterized in that, Five-coordinated Al in the alumina component 3+ Species account for a total of Al 3+ 50% to 70% of the species.

3. The catalyst according to claim 1, characterized in that, The specific surface area of ​​the alumina is 250.0~350.0 m². 2 / g; And / or, the pore volume of the alumina is 0.45~0.70 mL / g.

4. The catalyst according to claim 1, characterized in that, The molecules are screened from at least one of ZSM-5, ZSM-11, ZSM-22, ZSM-35, Beta, MOR, and Y.

5. The catalyst according to claim 4, characterized in that, The molecular sieve is at least one of ZSM-5, ZSM-11, and ZSM-22.

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

7. The catalyst according to claim 6, characterized in that, In the catalyst, the mass ratio of molecular sieve to alumina component is 3:1 to 1:

3.

8. The catalyst according to claim 7, characterized in that, In the catalyst, the mass ratio of molecular sieve to alumina component is 1:1 to 1:0.

5.

9. The catalyst according to claim 1, characterized in that, In the catalyst, the average particle size of the active metal Pt crystals is 0.20 nm to 0.50 nm.

10. A method for preparing the catalyst according to any one of claims 1-9, comprising the following steps: (1) Aluminum source, polymer, inorganic acid, alcohol and water are mixed to obtain precursor solution; (2) The precursor liquid is heat-treated, modified, and calcined to obtain alumina; (3) The Pt precursor solution is added dropwise to the alumina suspension obtained in step (2) to react and obtain active Pt / Al2O3; (4) The active Pt / Al2O3 obtained in step (3) is mixed with molecular sieve to obtain the alkane isomerization catalyst; The heat treatment temperature is 30~90 ℃, and the modification treatment is carried out in a closed environment with a temperature of 70~150 ℃, which is 20~80 ℃ higher than the heat treatment temperature.

11. The preparation method according to claim 10, characterized in that, In step (1), the aluminum source is calculated as Al2O3, the polymer is calculated as H2O, and the inorganic acid is calculated as H2O. + The mass ratio of Al2O3: polymer: inorganic acid: alcohol: H2O is 1:0.5~2.0:0.5~2.0:4.5~15:20~50.

12. The preparation method according to claim 10, characterized in that, In step (1), the polymer is selected from one or more of polyoxyethylene, polyoxypropylene, polyoxybutene, polyoxypropylene-polyoxyethylene, polyoxyethylene-polyoxybutene, polyoxypropylene-polyoxybutene, polyethylene oxide, polypropylene oxide, and polyethylene oxide-polypropylene 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; And / or, the alcohol is selected from at least one of methanol, ethanol, ethylene glycol, propanol, and glycerol.

13. The preparation method according to claim 12, characterized in that, In step (1), the polymer is selected from one or more of polyoxypropylene-polyoxyethylene, polyoxyethylene-polyoxybutene, and polyoxyethylene-polyoxypropylene-polyoxyethylene. And / or, the inorganic acid is selected from at least one of nitric acid and hydrochloric acid; And / or, the alcohol is ethanol.

14. The preparation method according to claim 10, characterized in that, In step (2), the heat treatment is carried out under stirring, the temperature of the heat treatment is 30~50 ℃, and the heat treatment time is 0.5 h~24 h; And / or, the modification treatment temperature is 70~100 ℃, and the modification treatment time is 5 h~60 h; And / or, the calcination conditions are as follows: calcination temperature is 350~750 ℃, and calcination time is 6~12 h.

15. The preparation method according to claim 14, characterized in that, In step (2), the heat treatment time is 4 h to 12 h; and / or, the modification treatment time is 24 h to 40 h.

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

1.

17. The preparation method according to claim 16, characterized in that, In step (3), the concentration of Pt in the Pt precursor solution is 0.1 mg. Pt / mL~1.5 mg Pt / mL; And / or, in step (4), the mass ratio of the active Pt / Al2O3 to the molecular sieve is 3:7 to 6:

4.

18. The preparation method according to claim 10, characterized in that, The preparation process of the alumina suspension is as follows: first, mix alumina with water and stir for 0.1~1.0h, then slowly add hydrochloric acid to adjust the pH value to 0.5~3.5, and continue stirring for 0.5~2.0h.

19. The use of any of the catalysts described in claims 1-9 in the catalytic isomerization reaction of C4-C8 alkane.

20. The application according to claim 19, characterized in that, The reaction conditions are as follows: reaction temperature 180~405℃, reaction pressure 1.0~3.0 MPa, hydrogen to alkane molar ratio 1.0~7.0, and alkane mass hourly space velocity 1.5~9.5 h⁻¹. -1 .

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