Highly dispersed catalyst, and preparation and use thereof

Abstract

The present invention relates to the field of chemical industry. Disclosed are an M / Al2O3 (M is Pd or Pt) catalyst, a preparation method therefor and a use thereof. The content of element M in the catalyst is 0.05-1.0 wt%. The active metal component M in the catalyst is supported in a monoatomic form on the surface of an Al2O3 support, wherein the average coordination number of M is 5.0 to 6.0 and the average valence state of M is +3.0 to +4.0. No M-M bond is present in the catalyst. The method for synthesizing the catalyst comprises: (a) performing gradient heating hydrothermal treatment on an alumina starting material, and performing drying and calcination to prepare an alumina support; and (b) contacting an M-containing solution with the alumina support for loading, and performing drying and calcination to provide the catalyst. The catalyst can be used in a reforming reaction (for example, isoparaffin to n-paraffin conversion) or a hydrogenation reaction (for example, a n-butene hydrogenation reaction), and has high activity and selectivity and also has high stability.

Description

Highly dispersed catalysts, their preparation and use TECHNICAL FIELD

[0001] The present invention belongs to the technical field of chemistry and chemical engineering, and particularly relates to a highly dispersed catalyst, a preparation method thereof and use thereof. BACKGROUND

[0002] Noble metal catalysts such as Pd, Pt, Au, Ru and Rh have been widely used in various catalytic fields. However, due to the high cost of noble metals, research on noble metal catalysts has gradually decreased from the nanoscale to the atomic scale, so that atoms are as exposed to the reaction system as possible to improve the utilization of atoms.

[0003] Currently, single-atom catalysts such as single-atom metal / carbon, single-atom metal / metal oxide, single-atom metal / metal sulfide, single-atom metal / alloy, etc. have shown great advantages in CO oxidation and selective oxidation, hydrogenation and selective hydrogenation, NO reduction and oxidation, water-gas shift, organic synthesis, methanol steam reforming, fuel cells, photoelectric catalysis, formaldehyde oxidation, etc. including high activity and selectivity. However, single-atom catalysts are prone to agglomeration and coupling to form larger particles during preparation and reaction, thereby leading to a significant decrease in activity. In addition, single-atom catalysts are sensitive to impurities in the reaction, leading to a rapid decrease in reaction activity.

[0004] It is desirable to provide a single-atom catalyst that has high activity and selectivity, while also having high stability and resistance to impurities.

[0005] n-Butane is an important petrochemical raw material and is currently used in large quantities to produce various organic chemical raw materials, such as butene and butadiene by dehydrogenation, maleic anhydride by catalytic oxidation, and halogenated butane by halogenation. Isobutane can be normal butane.

[0006] The core of the isobutane normal butane preparation technology is the catalyst. CN201510301472.5 (CN104892339A) discloses a method for preparing normal butane by hydrogenation of isobutane. Isobutane is first converted to normal butane in a normal butane reactor, then enters a hydrogenation saturation reactor to remove the olefins generated in the normal butane reaction, and then normal butane is obtained after separation. The isobutane normal butane catalyst in this document is a traditional chlorine-containing metal oxide catalyst, and the process conditions are 500°C and 3MPa. The catalyst in the method in this document contains chloride, which causes serious corrosion of the equipment and pollution to the environment, and the process temperature is high and the energy consumption is large.

[0007] CN201810379649.7 (CN108530254A) discloses a method for preparing n-butane from mixed C4, in which the mixed C4 is separated into isobutane by hydrogenation and desulfurization, and then n-butane is generated by normalizing reaction. The normalizing catalyst in the document is a metal-modified alumina catalyst, and the main problem is that the catalyst activity is low, the reaction temperature is > 400℃, and even as high as 600℃.

[0008] CN201910654290.4 (CN110385142A) discloses an isobutane normalizing reaction catalyst, which is prepared by impregnating zirconium salt and sulfate on MCM-41 molecular sieve as a carrier, drying and calcining to obtain a molecular sieve supported sulfated zirconium oxide catalyst, and adding platinum component. This kind of solid superacid catalyst does not contain chlorine, which can avoid corrosion to the equipment, but the disclosed process needs a hydrogen / isobutane feed volume ratio of 200:1, a large amount of hydrogen will significantly increase the cost of subsequent cryogenic separation, and the catalyst activity is low, and the reaction conversion rate is only about 25%.

[0009] The mainstream isobutane normalizing catalyst is a chlorine-containing catalyst, but the catalyst performance is not ideal, and the one-way yield of n-butane is generally only 30-35%. At the same time, chlorine forms hydrogen chloride and other compounds during the catalytic process and is lost. In order to maintain the activity of the catalyst, it is necessary to continuously supplement chlorine-containing compounds such as carbon tetrachloride and tetrachloroethylene, which will corrode the equipment and pollute the environment. In addition, the catalyst is extremely sensitive to water, sulfur, oxygen and other impurities, and generally needs to be controlled within 0.1-1 ppm.

[0010] A high-performance isomerized alkane normalizing catalyst without chlorine is urgently needed to be developed. SUMMARY

[0011] The present application provides a high-dispersion M / Al2O3 catalyst, which has high activity and / or selectivity, and at the same time has high stability and tolerance to impurities, wherein M is Pd and / or Pt, preferably Pt. In the present application, the "high dispersion" means that the active metal component M is dispersed in the form of a single atom on the Al2O3 carrier.

[0012] The catalyst of the present application does not contain chlorine and is not corrosive to the equipment. The catalyst of the present application has strong tolerance to water, oxygen, sulfur and other impurities, so that the raw material does not need to be purified harshly.

[0013] According to a first aspect of the present application, there is provided a catalyst comprising: an Al2O3 support and a metal active component M (M is Pd and / or Pt, preferably Pt), wherein the content of M element is 0.05-1.0% based on the total weight of the catalyst, and wherein the metal active component M is supported on the surface of the support in the form of single atom, and wherein the average coordination number (M-O bond number) of M is 5.0-6.0 and the average valence state of M is +3.0 to +4.0.

[0014] According to a second aspect of the present application, there is provided a method for preparing the catalyst as described in the present application, which comprises:

[0015] (a) gradient temperature hydrothermal treatment of an alumina raw material, and drying and calcination to prepare an alumina support;

[0016] (b) contacting a solution containing M with the alumina support for loading, and drying and calcination to provide the catalyst.

[0017] According to a third aspect of the present application, there is provided a method for preparing normal alkanes from isomeric alkanes, which comprises normalizing isomeric alkanes in the presence of the catalyst as described in the present application to obtain normal alkanes.

[0018] According to a fourth aspect of the present application, there is provided the use of the catalyst as described in the present application in a reforming reaction, preferably in an isomeric alkane normalizing reaction; preferably, the conditions of the isomeric alkane normalizing reaction comprise: a reaction temperature of 350-550°C, a pressure of 1-3 MPa, a weight hourly space velocity (WHSV) of isomeric alkanes of 0.5-3 h -1 , and a hydrogen / isomeric alkane molar ratio of 0.03-1.0. The isomeric alkanes can be selected from C4-C6 isomeric alkanes, preferably isobutane.

[0019] The catalyst of the present application has excellent impurity tolerance, for example, it can tolerate isobutane with high O, S, N impurities, for example, 200 ppm of oxygen-containing compounds, 2 ppm of nitrogen-containing compounds and 5 ppm of sulfur-containing compounds. This makes it unnecessary to perform harsh purification on the raw material. The catalyst of the present application can tolerate water, for example, it can tolerate up to 500 ppm of water, which makes it unnecessary to deeply dry the raw material. In the present application, "ppm" is ppm by weight, unless otherwise specified.

[0020] The catalyst of the present application has the characteristics of large specific surface area and pore size, no chlorine (no pollution to the environment, no corrosion to the equipment), high activity and selectivity, stable catalytic performance, etc. The catalyst of the present application can be used in reforming reactions, for example, in the production of normal alkanes by isomeric alkane isomerization; it can also be used in hydrogenation reactions, for example, in the hydrogenation reaction of n-butene.

[0021] When used in the production of n-alkanes by isomerization of iso-alkanes, the catalyst of the present application can increase product yield, reduce environmental pollution (as the catalyst does not contain chlorine and is not corrosive to equipment), and does not require harsh purification of raw materials (as it is highly resistant to impurities such as water, oxygen, sulfur, nitrogen, etc.).

[0022] The M in the catalyst of the present application has a high average coordination number and valence state, which indicates that the M has a stronger interaction with the carrier, making the M atoms more stable and helping to form a catalyst with improved stability.

[0023] The monatomic Pt catalyst synthesized in the present application remains in a monatomic state after long-term use at high temperature (350-550°C), for example, after 1200 hours of use, i.e., there are no Pt-Pt bonds in the catalyst.

[0024] In the present application, pressure is gauge pressure, unless otherwise specified. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a plot of the catalytic performance of catalyst Cat-2 as a function of reaction time;

[0026] Figure 2 is a plot of the catalytic performance of comparative catalyst Cat-DB1 as a function of reaction time;

[0027] Figure 3 is an XRD spectrum of comparative catalyst Cat-DB1 and example catalyst Cat-2;

[0028] Figure 4 is a spherical aberration electron microscope image of catalyst Cat-2;

[0029] Figure 5 is a spherical aberration electron microscope image of comparative catalyst Cat-DB1;

[0030] Figure 6 is an extended X-ray absorption fine structure spectrum of comparative catalyst Cat-DB1 and example catalyst Cat-2;

[0031] Figure 7 is a spherical aberration electron microscope image of catalyst Cat-2 before and after use in a catalytic reaction: (left) before reaction; (right) after reaction;

[0032] Figure 8 is an extended X-ray absorption fine structure spectrum of catalyst Cat-2 after use; and

[0033] Figure 9 is a spherical aberration electron microscope image of comparative catalyst Cat-DB1 after use. DETAILED DESCRIPTION

[0034] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not considered critical for the purposes of the application. The endpoints of the ranges and any values are provided as approximations only and are understood to encompass values approximately the same as the endpoints. Any numerical range recited herein is intended to include all sub-ranges of the same entire number excluding the single number at each end of the range if just the single number alone is recited as the end point. For example, a range of 1 to 10 should be read to include the range from 1 to 8, 1 to 9, 1 to 7, 2 to 10, 3 to 10, 4 to 10, 5 to 10, 6 to 10, and 7 to 10 etc.

[0035] The present application provides a catalyst comprising: an Al2O3 support and an active metal component M, wherein the content of M element is 0.05 to 1.0% based on the total weight of the catalyst, wherein the active metal component M is supported on the surface of the support in the form of single atom, wherein the average coordination number (M-O bond) of M atom is 5.0 to 6.0 and the average valence of M is +3.0 to +4.0, and wherein M is Pd and / or Pt, preferably Pt.

[0036] In the present application, the "average coordination number of M atom" refers to the average number of M-O bonds formed by M atom. For example, when M is Pt, the average number of Pt-O bonds formed by Pt atom is 5.0 to 6.0, i.e. the average coordination number of Pt atom is 5.0 to 6.0.

[0037] In the present application, the loading of M (the content of M element) refers to the mass ratio of M to the support (Al2O3).

[0038] In the present application, M is supported on the surface of the support in the form of single atom (i.e. in the form of atomic dispersion). In the present application, the number of M atoms around each M atom interacting with M atoms in the form of M-M bond is zero (i.e. there is no M-M bond in the catalyst); i.e. M is supported on the support in the form of single atom. In conventional non-single atom catalyst, the number of M around M interacting with M in the form of M-M bond is ≥2. When M is Pt, in the present application, the number of Pt atoms around each Pt atom interacting with Pt atoms in the form of Pt-Pt bond is zero (i.e. there is no Pt-Pt bond in the catalyst); i.e. Pt is supported on the support in the form of single atom. The catalyst of the present application is therefore also called single atom catalyst.

[0039] In the catalysts of the present application, the average coordination number of the M atoms (M-O bonds) is from 5.0 to 6.0. Preferably, in the catalysts of the present application, the average coordination number of the M atoms (M-O bonds) is from 5.0 to 5.7, more preferably from 5.1 to 5.7, and even more preferably from 5.2 to 5.6. In some embodiments, preferably, in the catalysts of the present application, the average coordination number of the M atoms (M-O bonds) is from 5.3 to 5.5. When the M atoms are Pt atoms, in the catalysts of the present application, the average coordination number of the Pt atoms (Pt-O bonds) is from 5.0 to 6.0. Preferably, in the catalysts of the present application, the average coordination number of the Pt atoms (Pt-O bonds) is from 5.0 to 5.7, more preferably from 5.1 to 5.7, and even more preferably from 5.2 to 5.6. In some embodiments, preferably, in the catalysts of the present application, the average coordination number of the Pt atoms (Pt-O bonds) is from 5.3 to 5.5. In contrast to the present application, in conventional Al2O3-supported single atom catalysts of the prior art, the coordination number of the Pt or Pd atoms is typically from 2 to 4.

[0040] In the catalysts of the present application, the valence state of the M atoms is from +3.0 to +4.0. Preferably, in the catalysts of the present application, the valence state of the M atoms can be from +3.3 to +4.0, more preferably from +3.4 to +4.0, and even more preferably from +3.5 to +3.9. In some embodiments, preferably, in the catalysts of the present application, the valence state of the M atoms can be from +3.6 to +3.8. When the M atoms are Pt atoms, in the catalysts of the present application, the valence state of the Pt atoms is from +3.0 to +4.0. Preferably, in the catalysts of the present application, the valence state of the Pt atoms can be from +3.3 to +4.0, more preferably from +3.4 to +4.0, and even more preferably from +3.5 to +3.9. In some embodiments, preferably, in the catalysts of the present application, the valence state of the Pt atoms can be from +3.6 to +3.8 or from +3.7 to +3.8. In contrast to the present application, in conventional Al2O3-supported single atom catalysts of the prior art, the valence state of the M single atoms is typically from 0 to +2.5.

[0041] According to some embodiments of the present application, the average valence state of M atoms in the catalysts of the present application is +1.6 to +3.0, for example +1.7 to +3.0, or +1.9 to +3.0 or +2.0 to +3.0, after the catalysts of the present application are treated at 350°C under an atmosphere of H2 / Ar (v / v = 1 :9) at normal pressure for 4 hours (also referred to as reduction treatment). In some embodiments, the average valence state of M atoms in the catalysts of the present application is preferably +1.7 to +2.8, for example +1.9 to +2.8, preferably +1.9 to +2.6, more preferably +2.0 to +2.8, more preferably +2.0 to +2.6, more preferably +2.0 to +2.5, further more preferably +1.9 to +2.4 or +2.0 to +2.4, after the catalysts of the present application are treated at 350°C under an atmosphere of H2 / Ar (v / v = 1 :9) at normal pressure for 4 hours. When the M atoms are Pt atoms, the average valence state of Pt atoms in the catalysts of the present application is +1.6 to +3.0, for example +1.7 to +3.0, or +1.9 to +3.0 or +2.0 to +3.0, after the catalysts of the present application are treated at 350°C under an atmosphere of H2 / Ar (v / v = 1 :9) at normal pressure for 4 hours; in some embodiments, it can be +1.7 to +2.8, for example +1.9 to +2.8, preferably +1.9 to +2.6, more preferably +2.0 to +2.8, more preferably +2.0 to +2.6, more preferably +2.0 to +2.5, further more preferably +1.9 to +2.4 or +2.0 to +2.4. Unlike the present application, the average valence state of M atoms in conventional Al2O3-supported M monatomic catalysts in the prior art is generally +1.0 to +1.7 valence, after the catalysts are treated in the same manner. In the present application, the pressure (absolute pressure) of the H2 / Ar (v / v = 1 :9) atmosphere is normal pressure, i.e. about one atmosphere.

[0042] According to some embodiments of the present application, for the catalysts of the present application, the ratio of the average valence state of the M atoms after the above reduction treatment to the average valence state of the M atoms before the treatment can be greater than or equal to 0.50 to less than or equal to 0.75, more preferably greater than 0.50 to less than or equal to 0.70. In some embodiments, the ratio of the average valence state of the M atoms after the above reduction treatment to the average valence state of the M atoms before the treatment can be greater than or equal to 0.51 to less than or equal to 0.69. In the present application, in some embodiments, the ratio of the average valence state of the M atoms after the above reduction treatment to the average valence state of the M atoms before the treatment can be 0.50, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.70, or a range between any two of the above values, for example, 0.51 to 0.67. In some embodiments, the ratio of the average valence state of the M atoms after the above reduction treatment to the average valence state of the M atoms before the treatment can be greater than or equal to 0.51 to less than or equal to 0.64.

[0043] According to some embodiments of the present application, for the catalysts of the present application, the difference between the average valence state of the M atoms before the above treatment and the average valence state of the M atoms after the treatment can be less than or equal to 2.0, for example, less than or equal to 1.95, preferably less than or equal to 1.9, for example, less than or equal to 1.85 or less than or equal to 1.80, and greater than or equal to 1.0, for example, greater than or equal to 1.1, preferably greater than or equal to 1.2, for example, greater than or equal to 1.3 or greater than or equal to 1.35. According to some embodiments of the present application, for the catalysts of the present application, the difference between the average valence state of the M atoms before the above treatment and the average valence state of the M atoms after the treatment can be greater than or equal to 1.0 and less than or equal to 2.0, for example, greater than or equal to 1.2 and less than or equal to 1.9, or greater than or equal to 1.3 and less than or equal to 1.85. According to some embodiments of the present application, for the catalysts of the present application, the difference between the average valence state of the M atoms before the above treatment and the average valence state of the M atoms after the treatment can be greater than or equal to 1.1 and less than or equal to 1.9.

[0044] In the present application, the average coordination number and the average valence state are determined by X-ray absorption fine structure (XAFS).

[0045] According to some embodiments of the present application, preferably, the AI2O3 support is γ- AI2O3.

[0046] According to some preferred embodiments of the present application, the amount of M element in the catalyst of the present application can be 0.05 to 0.8 wt%, 0.06 to 0.7 wt%, 0.07 to 0.6 wt% or 0.08 to 0.5 wt%, preferably can be 0.08 to 0.4 wt%, more preferably can be 0.1 to 0.4 wt%, 0.1 to 0.35 wt%, 0.1 to 0.30 wt% or 0.1 to 0.25 wt%; wherein the M is preferably Pt.

[0047] According to some embodiments of the present application, the amount of M element in the catalyst of the present application can be 0.01 wt%, 0.02 wt%, 0.03 wt%, 0.04 wt%, 0.05 wt%, 0.06 wt%, 0.07 wt%, 0.08 wt%, 0.09 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, or a range between any two of the above values, for example 0.02 to 0.5 wt%.

[0048] According to some embodiments of the present application, the specific surface area of the catalyst can be 200 to 330 m 2 / g, for example 200 to 320 m 2 / g, preferably 250 to 320 m 2 / g, for example 280 to 320 m 2 / g, 290 to 320 m 2 / g, more preferably 300 to 320 m 2 / g; the pore volume can be 0.6 to 1.5 cm 3 / g, for example 0.6 to 1.2 cm 3 / g or 0.8 to 1.2 cm 3 / g, preferably 0.9 to 1.1 cm 3 / g; and the average pore diameter can be 5 to 20 nm, preferably 8 to 16 nm or 11 to 15 nm.

[0049] In the present application, the specific surface area, pore volume and average pore diameter are tested by BET method.

[0050] According to some embodiments of the present application, the catalyst of the present application does not comprise an active metal component other than Pd and / or Pt. According to some embodiments of the present application, preferably, the catalyst of the present application does not comprise an active metal component other than Pt. According to some embodiments of the present application, preferably, the support of the catalyst consists of AI2O3, preferably of γ-AI2O3.

[0051] In some embodiments of the present application, the catalyst of the present application consists of the AI2O3 support and the active metal component M. In some embodiments of the present application, preferably, the catalyst of the present application consists of the AI2O3 support and the active metal component Pt.

[0052] In some embodiments of the present application, the catalyst of the present application does not contain a promoter element, for example, does not contain a Cl (chlorine) element.

[0053] The catalyst of the present application can be used in various reactions, for example, can be used in reactions for which catalysts using Pd and / or Pt as active components are generally used.

[0054] The catalyst of the present application can take various forms generally known in the art, including but not limited to powder, granule, regular shape such as strip, column, ring, sphere, etc., or irregular shape, and the like. The desired catalyst form can be appropriately selected by a person skilled in the art.

[0055] The catalyst of the present application can be used as a reforming catalyst, for example, for normalizing isomeric alkanes to normal alkanes, for example, the isomeric alkanes can be selected from C4-C6 isomeric alkanes, for example, isobutane, isopentane and isohexane, for example, normalizing isobutane to n-butane. The catalyst of the present application can also be used in hydrogenation reactions, for example, for hydrogenation of n-butenes.

[0056] The present application also provides a method for preparing the catalyst of the present application, which can comprise:

[0057] (a) gradient temperature hydrothermal treatment of an alumina raw material, and drying and calcination to prepare an alumina support;

[0058] (b) contacting a solution containing M with the alumina support for loading, and drying and calcination to provide the catalyst.

[0059] The method for preparing the catalyst of the present application comprises gradient temperature hydrothermal treatment of an alumina raw material before loading M to provide an alumina support. Without being bound by any theory, it is believed that the gradient temperature hydrothermal treatment in the present application enhances the interaction of M atoms with the support, making the M atoms more stable on the support, which helps to form high-valence, high-coordination M monatomic catalysts, and can increase the metal loading, while the catalyst has excellent conversion rate and selectivity and has excellent stability.

[0060] In the present application, "gradient temperature hydrothermal treatment" means that the temperature of the hydrothermal treatment is raised in stages (gradient); that is, after hydrothermal treatment at one temperature for a period of time, the temperature is raised to another temperature for a period of time, and so on until the hydrothermal treatment step is completed.

[0061] The present application does not have special requirements for the source or nature of the alumina raw material (solid), and the solid alumina raw material commonly used in the art can be used in the present application. According to some embodiments of the present application, the specific surface area of the alumina raw material can be 190-320 m 2 / g, for example 250-320 m 2 / g, the pore volume can be 0.9-2.0 cm 3 / g, for example 1.1-1.5 cm 3 / g, and the average pore diameter can be 5-15 nm, for example 9-15 nm.

[0062] According to some embodiments of the present application, the gradient temperature hydrothermal treatment uses an aqueous organic base solution, wherein the organic base is an amine. According to some preferred embodiments, the amine can be one or more selected from the group consisting of aliphatic amines, alcohol amines, alicyclic amines, aromatic amines, and combinations thereof; further preferably, the amine is one or more selected from the group consisting of pyridine, cyclohexylamine, piperidine, morpholine, pyrrole, tetrahydropyrrole, primary amine NH2R1, secondary amine NHR1R2, tertiary amine NR1R2R3, wherein the pyridine, cyclohexylamine, piperidine, morpholine, pyrrole and tetrahydropyrrole are optionally substituted with a substituent selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, butyl, and wherein R1, R2and R3are each independently methyl, ethyl, hydroxymethyl, hydroxyethyl, hydroxypropyl, n-propyl, isopropyl, butyl, phenyl or benzyl. Preferably, the amine can be selected from trimethylamine, triethylamine, triethanolamine, diisopropylamine, cyclohexylamine, piperidine, pyridine and aniline.

[0063] The concentration of the aqueous organic base solution can be easily selected by a person skilled in the art. According to some embodiments of the present application, the concentration of the aqueous organic base solution can be 0.5-10 wt%, for example 1-10 wt%, preferably 1-5 wt%.

[0064] The amount of the aqueous organic base solution used in the present application can be selected in a wide range. In some embodiments, preferably, the weight ratio of the aqueous organic base solution to the alumina raw material can be (3:1)-(10:1), preferably (4:1)-(7:1), for example 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, or a range consisting of any two of the above values.

[0065] The time of the gradient temperature hydrothermal treatment in the present application can be selected in a wide range. In some embodiments, preferably, the time of the gradient temperature hydrothermal treatment can be 1-120 h, preferably 2-72 h, more preferably 3-48 h or 2-24 h. In the present application, the time of the gradient temperature hydrothermal treatment refers to the sum of the treatment times of all gradients of the gradient temperature hydrothermal treatment, as understood by a person skilled in the art.

[0066] In the present application, the temperature of the gradient temperature hydrothermal treatment can be selected in a wide range. In some embodiments, preferably, the temperature of the hydrothermal treatment can be 50-130°C or 55-130°C, preferably 60-120°C or 60-110°C. In some embodiments, the gradient temperature treatment has a starting temperature of 50-80°C or 50-80°C and a final temperature of 90-130°C or 90-125°C, and the gradient temperature treatment comprises at least 2 gradients, for example 2-10 gradients, preferably 3-10 gradients, for example 2, 3, 4, 5, 6, 7, 8, 9 or 10 gradients, wherein the temperature difference between each two adjacent gradients can be independently of each other 5-40°C, preferably 10-30°C, for example can be 15-25°C; for example the temperature difference between each two adjacent gradients can be independently of each other 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C or 40°C. In the present application, the time of each gradient in the gradient temperature hydrothermal treatment can be 0.5-24h, for example can be 0.5-18h, 1-18h, 1-12h, or 1-8h, preferably can be 0.5-6h or 1-6h or 1-5h.

[0067] According to a more preferred embodiment of the present application, the gradient temperature step of the hydrothermal treatment comprises: treating at temperature T°C, (T+20) °C, (T+40) °C for 0.5-10h, preferably 0.5-5h or 1-4h, respectively; wherein T is 50-85 or 50-80 or 55-80. In this embodiment, the hydrothermal treatment is divided into three gradients, and the temperature difference between each two adjacent gradients is 20°C.

[0068] In the present application, the pressure of the gradient temperature treatment is the water vapor pressure naturally generated during the treatment (i.e. the water vapor pressure itself).

[0069] In the present application, after the hydrothermal treatment of the alumina raw material, drying and calcination are performed to prepare the alumina carrier.

[0070] The conditions of the drying can be selected in a wide range, and the commonly used drying conditions after the hydrothermal treatment can be applied to the present application. In some embodiments, preferably, the drying conditions comprise: temperature 100-200°C, air atmosphere drying for 1-48h or 1-24h.

[0071] In the present application, the calcination conditions can be selected from a wide range, and the calcination conditions commonly used after hydrothermal treatment can be used in the present application. In some embodiments, γ-Al2O3 is obtained as the support after calcination. In some embodiments, preferably, the calcination conditions include: air atmosphere, calcination temperature of 450 to 580°C or 450 to 560°C or 450 to 550°C, and constant temperature time of 3 to 8 h or 3 to 6 h. The present application does not have special requirements for the source of the alumina raw material, and for example, commercially available alumina can be used. According to some embodiments of the present application, the alumina raw material can be prepared by an aluminum salt precipitation method.

[0072] In the present application, the type of the aluminum salt can be selected from a wide range, and various aluminum salts commonly used in the aluminum salt precipitation method for preparing alumina can be used. According to some preferred embodiments of the present application, the aluminum salt can be one or more of aluminum nitrate and its hydrates, aluminum sulfate and its hydrates, and combinations thereof. The aluminum salt is used in the form of an aqueous aluminum salt solution, and the mass concentration of the aqueous aluminum salt solution can be, for example, 10 to 30%.

[0073] In the present application, the type of the precipitant in the aluminum salt precipitation method can be selected from a wide range, and the precipitants commonly used in the aluminum salt precipitation method can be used in the present application. In some preferred embodiments, the precipitant can be concentrated ammonia water, and the mass concentration of the concentrated ammonia water can be 25 to 28%. In the aluminum salt precipitation method, preferably, the precipitation pH is controlled to be 8.0 to 9.5 or 8.5 to 9.0.

[0074] According to some embodiments of the present application, the aluminum salt precipitation method for preparing the alumina raw material can include: adding a precipitant dropwise to an aqueous aluminum salt solution (optionally stirring) to generate an alumina gel, aging, filtering, washing with deionized water until the filtrate is neutral, drying, for example, oven drying, and calcining to obtain the alumina raw material. In the present application, preferably, the aluminum salt can be one or more of aluminum nitrate, aluminum sulfate and its hydrates, and the mass fraction of the aqueous aluminum salt solution can be 10 to 30%. In the present application, the precipitant can be concentrated ammonia water, and the mass fraction of the concentrated ammonia water can be 25 to 28%. In the aluminum salt precipitation method, the pH of the final solution can be controlled to be 8.0 to 9.5 or 8.5 to 9.0.

[0075] In the present application, in some embodiments, the reaction temperature in the aluminum salt precipitation method can be 40 to 80°C, the aging temperature can be 60 to 100°C, and the aging time can be 2 to 24 h or 2 to 12 h.

[0076] In the process of the present application, after obtaining the alumina support, Pd and / or Pt is supported on the support. In some embodiments, a solution containing Pd and / or Pt is contacted with the alumina support for supporting, preferably, the supporting is performed using an incipient wetness impregnation method. After supporting the metal, the alumina support supporting Pd and / or Pt can be dried and calcined to obtain the catalyst.

[0077] The solution containing Pt can be obtained by dissolving a platinum organic compound or a platinum salt in a solvent, such as water. The platinum organic compound and the platinum salt can be those commonly used as a Pt precursor in the art, for example, can be selected from the group consisting of chloroplatinic acid and chloroplatinic acid salts such as sodium chloroplatinate, potassium chloroplatinate, ammonium chloroplatinate, platinous chloride, platinum chloride, diethylamine platinum chloride, platinum nitrate, 1,5-cyclooctadiene platinum dichloride, dimethyl(1,5-cyclooctadiene)platinum, tetraammine platinum dichloride, benzenedinitrile platinum dichloride, bis(triphenylphosphine)platinum dichloride, acetylacetonate platinum, diammine platinum hexachloride, diaminodinitrosoplatinum, dihydrogen hexachloroplatinate hydrate, tetraammine platinum nitrate, and combinations thereof.

[0078] The solution containing Pd can be obtained by dissolving a palladium organic compound or a palladium salt in a solvent, such as water. The palladium organic compound and the palladium salt can be those commonly used as a Pd precursor in the art, for example, can be selected from the group consisting of palladium chloride, palladium nitrate, chloropalladous acid, tetraammine palladium dichloride, diammine palladium dichloride, dinitro tetraammine palladium, palladium acetate, palladium sulfate, palladium trifluoroacetate, palladium acetylacetonate, potassium hexachloropalladate, ammonium hexachloropalladate, tetraammine palladium acetate, sodium tetrachloropalladate, potassium tetrachloropalladate, ammonium tetrachloropalladate, potassium tetracyanopalladate, potassium tetrabromopalladate, palladium neopentanoate, palladium cyanide, palladium bromide, palladium thiosulfate, palladium iodide, sulfonated palladium, [1,3-bis(diphenylphosphino)propane]palladium chloride, (1,5-cyclooctadiene)palladium dichloride, (2,2'-bipyridine)palladium dichloride, [1,2-bis(diphenylphosphino)ethane]palladium dichloride, 1,4-bis(diphenylphosphino)butane-palladium chloride, or diaminodichloropalladium. In the present application, a solution of palladium salt complexed with a complexing agent can also be used, for example, an impregnation can be performed using a solution of palladium chloride / ethylenediamine complex.

[0079] In the present application, the loading amount of Pt and / or Pd can be controlled by controlling the amount and concentration of the solution containing Pd and / or Pt.

[0080] In the present application, the drying conditions after supporting Pd and / or Pt can be widely selected, and commonly used drying conditions can be used in the present application. In some embodiments, preferably, the drying conditions can include a temperature of 100-200°C or 100-150°C, a time of 1-48h, 1-24h, or 12-24h, and an atmosphere of air.

[0081] In the present invention, the conditions for the calcination after loading Pd and / or Pt can be selected in a wide range, and the commonly used calcination conditions can be used in the present invention. In some embodiments, preferably, the calcination conditions can include: air atmosphere, calcination temperature 450-550°C, and constant temperature time 3-6h.

[0082] In the present invention, the specific surface area of the alumina support can be 220-350m 2 / g, 280-350m 2 / g, or 300-350m 2 / g, the pore volume can be 0.6-2.0cm 3 / g, 0.6-1.5cm 3 / g, 0.6-1.2cm 3 / g, or 0.9-1.3cm 3 / g, and the average pore diameter d0 can be 5-20nm, preferably 9-15nm. In the present invention, preferably, the BJH adsorption median pore diameter of the alumina support is d1 and the BJH adsorption most probable pore diameter is d2, wherein d0 / d1 can be 0.90-1.20 and d0 / d2 can be 0.90-1.25, preferably d0 / d1 can be 0.90-1.15 and d0 / d2 can be 0.90-1.20.

[0083] In the method of the present invention, mixing can be carried out by stirring, ultrasonic, etc. according to the mixing needs, and the present invention has no special requirements for these operations. In the method of the present invention, filtering, washing, etc. can be carried out according to the needs, and the present invention has no special requirements for these operations.

[0084] According to a preferred embodiment of the present invention, the present invention provides a method for synthesizing the catalyst of the present invention, comprising:

[0085] (1) optionally, preparing the alumina raw material by precipitation method: adding concentrated ammonia water dropwise into an aqueous solution of aluminum salt under stirring to form an alumina gel, aging, filtering, washing with deionized water until the filtrate is neutral, drying, and calcining to obtain a solid alumina raw material;

[0086] (2) preparing the support by hydrothermal treatment: adding the above alumina raw material and an aqueous solution of organic base into a hydrothermal crystallization kettle, and treating by gradient heating under rotation (i.e. rotating the hydrothermal crystallization kettle up and down), filtering, washing, drying and calcining the filter cake, and grinding into powder;

[0087] (3) preparing the catalyst: impregnating the powder of the support with an equal volume of a solution of platinum precursor, such as chloroplatinic acid, or palladium precursor, such as aqueous solution, drying, calcining, tabletting, crushing, and sieving to obtain the catalyst.

[0088] In the above method of the present application, preferably, the aluminum salt in step (1) is one or more of aluminum nitrate, aluminum sulfate and hydrates thereof, the mass fraction of the aqueous aluminum salt solution is 10-30%, the mass fraction of the concentrated ammonia water is 25-28%, the pH of the final solution is 8.5-9.0, the reaction temperature is 40-80°C, the aging temperature is 60-100°C, and the aging time is 2-12h. Preferably, the drying temperature in step (1) is 100-200°C, and the drying time is 6-24h; the calcination conditions are 450-550°C under air atmosphere, and the constant temperature time is 3-6h.

[0089] In the above method of the present application, the specific surface area of the aluminum oxide raw material obtained according to step (1) can be 190-320m 2 / g, the pore volume can be 1.1-1.5cm 3 / g, and the average pore size can be 5-15nm.

[0090] In the above method of the present application, preferably, the concentration of the aqueous organic base solution used in the hydrothermal treatment of step (2) is 1-5% by weight; the weight ratio of the aqueous organic base solution to the solid aluminum oxide raw material is (3:1)-(10:1); the hydrothermal treatment is a gradient temperature raising treatment, respectively at temperatures T°C, (T+20)°C and (T+40)°C for 0.5-10h each, wherein T is 50-80.

[0091] In the above method of the present application, the specific surface area of the support obtained according to step (2) can be 220-350m 2 / g, the pore volume can be 0.6-1.2cm 3 / g, and the average pore size can be 5-20nm, for example, 9-15nm.

[0092] In the above method of the present application, step (3) uses an equal volume impregnation method to introduce Pd or Pt components, and the mass ratio of Pd or Pt to the support, calculated as metal elements, is 0.1-1.0%; the drying temperature is 100-200°C, and the drying time is 6-24h; the calcination conditions are 450-550°C under air atmosphere, and the constant temperature time is 3-6h.

[0093] In the above method of the present application, the catalyst prepared in step (3) is composed of (support) Al2O3 and the metal active component Pd or Pt, and the content of Pd or Pt elements, calculated as the weight of the catalyst, is 0.05-1.0% mass fraction, preferably 0.1-0.5% or 0.2-0.5% mass fraction; the Al2O3 crystal form is γ-Al2O3; the specific surface area is 200-320m 2 / g, for example, 290-320m 2 / g, and the pore volume is 0.6-1.5cm3 / g, for example 0.6 to 1.2 cm 3 / g, with an average pore diameter of 5 to 20 nm; the number of M atoms acting with M-M bonds around each active metal atom is 0 (i.e. there are no M-M bonds in the catalyst), i.e. the M atoms are dispersed in monatomic form on the surface of the support; the average coordination number of the M atoms is 5.0 to 6.0 and the average valence of M is +3.0 to +4.0.

[0094] The catalysts of the present application have an average valence state of the M atoms of +1.6 to +3.0 valence or +2.0 to +3.0 valence or +2.0 to +2.4 valence after being subjected to a 4 hour treatment (i.e., a reduction treatment) at 350 °C under an atmosphere of H2 / Ar (v / v = 1 :9) at atmospheric pressure. When M is Pt, the catalysts of the present application have an average valence state of the Pt atoms of +1.6 to +3.0 valence or +2.0 to +3.0 valence or +2.0 to +2.4 valence after being subjected to a 4 hour treatment at 350 °C under an atmosphere of H2 / Ar (v / v = 1 :9) at atmospheric pressure. According to some embodiments of the present application, the ratio of the average valence state of the M atoms after the above reduction treatment to the average valence state of the M atoms prior to the treatment can be greater than or equal to 0.50 to less than or equal to 0.75, more preferably greater than 0.50 to less than or equal to 0.70, for the catalysts of the present application. In some embodiments, the ratio of the average valence state of the M atoms after the above reduction treatment to the average valence state of the M atoms prior to the treatment can be greater than or equal to 0.51 to less than or equal to 0.69. In some embodiments of the present application, the ratio of the average valence state of the M atoms after the above reduction treatment to the average valence state of the M atoms prior to the treatment can be 0.50, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.70, or a range between any two of the above values, e.g., 0.51 to 0.67. In some embodiments, the ratio of the average valence state of the M atoms after the above reduction treatment to the average valence state of the M atoms prior to the treatment can be greater than or equal to 0.51 to less than or equal to 0.64. According to some embodiments of the present application, the difference between the average valence state of the M atoms prior to the above treatment and the average valence state of the M atoms after the treatment can be less than or equal to 2.0, e.g., less than or equal to 1.95, preferably less than or equal to 1.9, e.g., less than or equal to 1.85 or less than or equal to 1.80, and greater than or equal to 1.0, e.g., greater than or equal to 1.1, preferably greater than or equal to 1.2, e.g., greater than or equal to 1.3 or greater than or equal to 1.35, for the catalysts of the present application. According to some embodiments of the present application, the difference between the average valence state of the M atoms prior to the above treatment and the average valence state of the M atoms after the treatment can be greater than or equal to 1.0 and less than or equal to 2.0, e.g., greater than or equal to 1.2 and less than or equal to 1.9, or greater than or equal to 1.3 and less than or equal to 1.85, for the catalysts of the present application. According to some embodiments of the present application, the difference between the average valence state of the M atoms prior to the above treatment and the average valence state of the M atoms after the treatment can be greater than or equal to 1.1 and less than or equal to 1.9, for the catalysts of the present application.

[0095] The present application also provides a method for preparing normal alkanes from isomeric alkanes, which comprises normalizing isomeric alkanes in the presence of the catalyst of the present application to obtain normal alkanes. In some embodiments, the isomeric alkanes can be C4-C6 isomeric alkanes. In some preferred embodiments, the isomeric alkanes are isobutane and the normal alkanes are n-butane.

[0096] The present application also provides the use of the catalyst of the present application in a reforming reaction, preferably in an isomeric alkane normalizing reaction. In the present application, in some embodiments, the conditions of the isomeric alkane normalizing reaction can preferably comprise: a reaction temperature of 350-550°C, a pressure of 1-3 MPa, a WHSV of isomeric alkanes of 0.5-3 h -1 , and a hydrogen / isomeric alkane molar ratio of 0.03-1.0. In some embodiments, the reaction temperature of the isomeric alkane normalizing reaction can be 350°C, 370°C, 390°C, 410°C, 430°C, 450°C, 470°C, 490°C, 510°C, 530°C, 550°C, or a range formed by any two of the above values, for example 400-500°C.

[0097] In the present application, various isomeric alkanes can be normalized using the catalyst of the present application. Preferably, the isomeric alkanes can be selected from C4-C6 isomeric alkanes, preferably isobutane.

[0098] The catalyst of the present application has excellent stability, wherein after 1200 hours of use in a reaction at 350-550°C, there is still no M-M bond in the catalyst, preferably M is Pt, and preferably the reaction is a reforming reaction, more preferably an isomeric alkane normalizing reaction, most preferably an isobutane normalizing reaction.

[0099] The present application will be described in detail below by way of examples. In the following examples:

[0100] The raw materials and reagents used are all analytical pure reagents sold by National Pharmaceutical Reagent Co., Ltd.

[0101] The conversion rate and selectivity are calculated using gas chromatography area normalization method, and the instrument is Agilent GC-6890 equipped with a hydrogen flame ionization detector.

[0102] The XRD test uses a D8 Advance diffractometer produced by Germany Bruker Company, CuKα1 is the radiation source, the tube voltage is 40 kV, the tube current is 40 mA, and the scanning range 2θ is 5 o - 85 o , step size is 0.02 o .

[0103] Specific surface area tests (BET) were performed on a Micromeritics ASAP-2020 specific surface and pore size analyzer. The samples were first activated at 573 K and vacuumed to 5 mmHg, then the specific surface area, pore volume and pore size tests were performed at liquid nitrogen temperature (77 K); and the average pore diameter d0, the median pore diameter d1 and the most probable pore diameter d2 of adsorption were obtained according to the BJH method.

[0104] High resolution transmission electron microscopy (HRTEM) tests were performed on a FEI Titan Cubed Themis G2 300 electron microscope from FEI Company, USA. The catalysts were calcined in air at 550 °C for 4 hours before testing to remove the coke on the surface of the catalysts.

[0105] X-ray absorption fine structure (XAFS) of the samples were collected at the BL11B beamline station of Shanghai Synchrotron Radiation Facility. First, the XAFS spectrum of Pt foil was tested in transmission mode using a Si(111) monochromator to calibrate the energy. For the catalyst samples, the fluorescence mode was used after pressing. The IFEFFIT software package was used for data processing and analysis. Among them, the average coordination number of Pt was obtained by fitting using Artemis software: first, the model of single atom catalyst of Pt was established using Materials Studio and VESTA software, then the constructed model was imported into Artemis software, and the structure parameters of the model were adjusted, the bond length, coordination number, disorder degree and other information of the catalyst model were optimized, so that the fitted EXAFS spectrum (extended X-ray absorption spectrum) was consistent with the experimental spectrum (basic), that is, the average coordination number and coordination type (Pt-O, Pt-Pt, etc.) of Pt were obtained; see Conflicting Roles of Coordination Number on Catalytic Performance of Single Atom Pt Catalysts, ACS Catal. 2021, 11, 5586-5592. The average valence of Pt was calculated by the absorption peak area and the valence-absorption peak area normalization curve of the standard sample (Pt foil and PtO2) with known valence; see Quantitative determination of average rhodium oxidation state by a simple XANES analysis, Applied Catalysis B: Environmental 111-112 (2012) 509-514. The average coordination number and average valence of Pd were obtained using a similar method.

[0106] The application will be described in detail below with reference to the examples, but the application is not limited by the following examples.

[0107] Example 1

[0108] The temperature of the solution was controlled at 50-55°C, and concentrated ammonia was added dropwise into 20wt% aluminum sulfate aqueous solution under rapid stirring until the pH of the solution was 8.5 to form an aluminum oxide gel; the gel was aged at 90°C for 6h; the gel was filtered and washed with deionized water until neutral, and then dried at 110°C for 24h and calcined at 500°C for 4h to obtain aluminum oxide. The specific surface area of the aluminum oxide was 292m 2 / g, the pore volume was 1.2cm 3 / g, and the average pore size was 12.8nm.

[0109] In a hydrothermal crystallization kettle, 30g of aluminum oxide, 150g of 4.0wt% triethylamine aqueous solution were added, and the mixture was treated at 60°C, 80°C and 100°C respectively under rotation for 3h, then filtered, the filter cake was dried at 110°C for 12h and calcined at 550°C for 4h, and then ground for use. After the hydrothermal treatment, the specific surface area of the aluminum oxide was 323m 2 / g, the pore volume was 1.1cm 3 / g, and the average pore size was 14.1nm.

[0110] 10g of the powder was taken, and an equal volume of chloroplatinic acid aqueous solution was used for impregnation, wherein the Pt element loading was 0.1% by mass, and then the mixture was dried at 110°C for 24h and calcined at 500°C for 4h in air, and then the catalyst particles of 20-40 mesh were obtained by tabletting, crushing and sieving, and the catalyst was recorded as catalyst Cat-1. The specific surface area of the catalyst was 310m 2 / g, the pore volume was 1.0cm 3 / g, and the average pore size was 14.3nm.

[0111] Example 2

[0112] The temperature of the solution was controlled at 45-50°C, and concentrated ammonia was added dropwise into 20wt% aluminum nitrate aqueous solution under rapid stirring until the pH of the solution was 9.0 to form an aluminum oxide gel; the gel was aged at 100°C for 6h; the gel was filtered and washed with deionized water until neutral, and then dried at 110°C for 24h and calcined at 500°C for 4h to obtain aluminum oxide. The specific surface area of the aluminum oxide was 306m 2 / g, the pore volume was 1.5cm 3 / g, and the average pore size was 11.6nm.

[0113] In a hydrothermal reactor, 30 g of alumina, 150 g of 3.0 wt% triethanolamine aqueous solution were added, and treated at 70°C, 90°C, 110°C respectively under rotating condition for 1.5 h, filtered, the filter cake was dried at 120°C for 6 h, and calcined at 550°C for 5 h, and grinded for use. After hydrothermal treatment, the specific surface area of the alumina was 330 m 2 / g, the pore volume was 1.1 cm 3 / g, and the average pore size was 12.0 nm.

[0114] 10 g of the powder was taken, and an equal volume of an aqueous chloroplatinic acid solution was impregnated, wherein the Pt element loading was 0.15% by mass, and the impregnated sample was dried at 110°C for 24 h, and calcined at 500°C for 4 h in air, and after tabletting, crushing and sieving, catalyst particles of 20-40 mesh were obtained, and were recorded as catalyst Cat-2. The specific surface area of the catalyst was 304 m 2 / g, the pore volume was 0.9 cm 3 / g, and the average pore size was 12.0 nm.

[0115] The XRD pattern is shown in Figure 3. Figure 3 shows that the crystal phase of the catalyst Cat-2 is γ-Al2O3. The XRD patterns of the catalysts of other examples of the present application also show that they are γ-Al2O3.

[0116] The HRSEM pattern is shown in Figure 4. Figure 4 shows that the Pt component in the catalyst Cat-2 is dispersed in monatomic form on the surface of the carrier. The HRSEM patterns of the catalysts of other examples of the present application also show that the Pt or Pd component is dispersed in monatomic form on the surface of the carrier.

[0117] The extended edge X-ray absorption spectrum is shown in Figure 6. Figure 6 shows that in the catalyst Cat-2, in addition to the Pt-O bond, there is no Pt-Pt bond, which shows that there is no aggregation of Pt atoms, i.e. clusters or nanoparticles, in the catalyst.

[0118]

Example 3

[0119] The temperature of the solution was controlled at 55-60°C, and under rapid stirring, concentrated ammonia water was added dropwise to the 20 wt% aluminum nitrate aqueous solution until the pH of the solution was 8.5, and an alumina gel was formed; the gel was aged at 95°C for 6 h; filtered, washed with deionized water until neutral, dried at 110°C for 24 h, and calcined at 500°C for 4 h, and alumina was obtained. The specific surface area of the alumina was 304 m 2 / g, the pore volume was 1.1 cm 3 / g, and the average pore size was 11.8 nm.

[0120] In a hydrothermal crystallization kettle, 30 g of the alumina, 150 g of 3.0 wt% diisopropylamine aqueous solution were added, and treated at 75°C, 95°C, 115°C respectively for 2 h under rotating condition, filtered, the filter cake was dried at 100°C for 24 h and calcined at 550°C for 6 h, and ground for use. After hydrothermal treatment, the specific surface area of the alumina was 335 m 2 / g, the pore volume was 1.0 cm 3 / g, and the average pore diameter was 12.8 nm.

[0121] 10 g of the powder was taken, and an equal volume of chloroplatinic acid aqueous solution was impregnated, wherein the Pt element loading was 0.20% by mass, dried at 110°C for 24 h, calcined at 500°C for 4 h in air, and after tabletting, crushing and sieving, catalyst particles of 20-40 mesh were obtained, and were recorded as catalyst Cat-3. The specific surface area of the catalyst was 311 m 2 / g, the pore volume was 1.0 cm 3 / g, and the average pore diameter was 12.1 nm.

[0122] [Example 4]

[0123] The temperature of the solution was controlled at 65-70°C, and concentrated ammonia water was added dropwise to the 20 wt% aluminum nitrate aqueous solution under rapid stirring until the pH of the solution was 9.0, and an alumina gel was formed; the alumina gel was aged at 85°C for 10 h; filtered, washed with deionized water until neutral, dried at 110°C for 24 h, and calcined at 500°C for 4 h to obtain alumina. The specific surface area of the alumina was 280 m 2 / g, the pore volume was 1.4 cm 3 / g, and the average pore diameter was 10.3 nm.

[0124] In a hydrothermal crystallization kettle, 30 g of the alumina, 150 g of 5.0 wt% cyclohexylamine aqueous solution were added, and treated at 70°C, 90°C, 110°C respectively for 2 h under rotating condition, filtered, the filter cake was dried at 150°C for 4 h and calcined at 500°C for 6 h, and ground for use. The specific surface area of the alumina was 301 m 2 / g, the pore volume was 1.2 cm 3 / g, and the average pore diameter was 10.7 nm.

[0125] 10 g of the powder was taken, and an equal volume of chloroplatinic acid aqueous solution was impregnated, wherein the Pt element loading was 0.1% by mass, dried at 110°C for 24 h, calcined at 500°C for 4 h in air, and after tabletting, crushing and sieving, catalyst particles of 20-40 mesh were obtained, and were recorded as catalyst Cat-4. The specific surface area of the catalyst was 293 m 2 / g, the pore volume was 0.9 cm 3 / g, and the average pore diameter was 10.0 nm.

[0126] [Example 5]

[0127] The temperature of the solution was controlled at 60-65°C, and concentrated ammonia was added dropwise into 20wt% aluminum sulfate aqueous solution under rapid stirring until the pH of the solution was 9.0 to form an aluminum oxide gel; the gel was aged at 80°C for 12h; filtered, washed with deionized water until neutral, dried at 110°C for 24h, and calcined at 500°C for 4h to obtain aluminum oxide. The specific surface area of the aluminum oxide was 295m 2 / g, the pore volume was 1.3cm 3 / g, and the average pore size was 12.2nm.

[0128] In a hydrothermal crystallization kettle, 30g of aluminum oxide, 150g of 2.5wt% piperidine aqueous solution were added, and treated at 65°C, 85°C, 105°C respectively under rotation for 3h, filtered, the filter cake was dried at 160°C for 4h and calcined at 560°C for 4h, and then ground for use. The specific surface area of the aluminum oxide was 317m 2 / g, the pore volume was 1.1cm 3 / g, and the average pore size was 12.5nm.

[0129] 10g of the powder was taken, and an equal volume of chloroplatinic acid aqueous solution was used for impregnation, wherein the Pt element loading was 0.1% by mass, dried at 110°C for 24h, and calcined at 500°C for 4h in air to obtain catalyst particles of 20-40 mesh, which was recorded as catalyst Cat-5. The specific surface area of the catalyst was 302m 2 / g, the pore volume was 1.1cm 3 / g, and the average pore size was 12.0nm.

[0130]

Example 6

[0131] The temperature of the solution was controlled at 70-75°C, and concentrated ammonia was added dropwise into 20wt% aluminum nitrate aqueous solution under rapid stirring until the pH of the solution was 9.0 to form an aluminum oxide gel; the gel was aged at 100°C for 3h; filtered, washed with deionized water until neutral, dried at 110°C for 24h, and calcined at 500°C for 4h to obtain aluminum oxide. The specific surface area of the aluminum oxide was 310m 2 / g, the pore volume was 1.4cm 3 / g, and the average pore size was 10.9nm.

[0132] In a hydrothermal crystallization kettle, 30g of aluminum oxide, 150g of 1.0wt% triethanolamine aqueous solution were added, and treated at 80°C, 100°C, 120°C respectively under rotation for 1h, filtered, the filter cake was dried at 100°C for 15h and calcined at 520°C for 6h, and then ground for use. The specific surface area of the aluminum oxide was 324m 2 / g, the pore volume was 1.2cm 3 / g, and the average pore size was 10.2nm.

[0133] Take 10 g of powder, equal volume of impregnation of chloroplatinic acid aqueous solution, wherein the Pt element loading is 0.1 wt% mass, 110 ℃ drying 24 h, in air, 500 ℃ calcination 4 h, after tabletting molding, broken sieve after 20-40 mesh catalyst particles, recorded as catalyst Cat-6. The specific surface area of the catalyst is 311 m 2 / g, pore volume is 1.1 cm 3 / g and the average pore size is 9.7 nm.

[0134]

Example 7

[0135] Control the solution temperature 55-60 ℃, under rapid stirring, to 20 wt% aluminum sulfate aqueous solution dropwise add concentrated ammonia water to the solution pH is 9.0, the formation of alumina gel; 90 ℃, 10 h; filtration, deionized water washing to neutral, 110 ℃ drying 24 h, 500 ℃ calcination 4 h, get alumina. The specific surface area of the alumina is 298 m 2 / g, pore volume is 1.6 cm 3 / g and the average pore size is 12.0 nm.

[0136] In the hydrothermal crystallization kettle, add 30 g of alumina, 150 g of 1.0 wt% aniline aqueous solution, under the rotating conditions, respectively, at 60 ℃, 80 ℃, 100 ℃ for 4 h, filtration, filter cake 200 ℃ drying 2 h, 550 ℃ calcination 4 h, grinding for use. The specific surface area of the alumina is 313 m 2 / g, pore volume is 1.3 cm 3 / g and the average pore size is 12.6 nm.

[0137] Take 10 g of powder, equal volume of impregnation of chloroplatinic acid aqueous solution, wherein the Pt element loading is 0.1 wt% mass, 110 ℃ drying 24 h, in air, 500 ℃ calcination 4 h, after tabletting molding, broken sieve after 20-40 mesh catalyst particles, recorded as catalyst Cat-7. The specific surface area of the catalyst is 301 m 2 / g, pore volume is 1.3 cm 3 / g and the average pore size is 12.3 nm.

[0138]

Example 8

[0139] Control the solution temperature 45-50 ℃, under rapid stirring, to 20 wt% aluminum nitrate aqueous solution dropwise add concentrated ammonia water to the solution pH is 9.0, the formation of alumina gel; 100 ℃, 4 h; filtration, deionized water washing to neutral, 110 ℃ drying 24 h, 500 ℃ calcination 4 h, get alumina. The specific surface area of the alumina is 288 m 2 / g, pore volume is 1.6 cm 3 / g and average pore diameter of 13.0 nm.

[0140] In a hydrothermal crystallization kettle, 30 g of the alumina, 150 g of 1.0 wt% pyridine aqueous solution were added, and treated at 70°C, 90°C, 110°C respectively for 3 h under rotating condition, filtered, the filter cake was dried at 110°C for 12 h and calcined at 550°C for 4 h, and ground for use. The specific surface area of the alumina was 301 m 2 / g, pore volume was 1.4 cm 3 / g and average pore diameter of 14.1 nm.

[0141] 10 g of the powder was taken, and an equal volume of an aqueous solution of chloroplatinic acid was impregnated, wherein the Pt element loading was 0.1 wt% mass, dried at 110°C for 24 h, calcined at 500°C for 4 h in air, and after tabletting, crushing and sieving, catalyst particles of 20-40 mesh were obtained, and recorded as catalyst Cat-8. The specific surface area of the catalyst was 293 m 2 / g, pore volume was 1.4 cm 3 / g and average pore diameter of 14.0 nm.

[0142] [Example 9]

[0143] The temperature of the solution was controlled at 45-50°C, and concentrated ammonia water was added dropwise to the 20 wt% aluminum nitrate aqueous solution under rapid stirring until the pH of the solution was 9.0, and an alumina gel was generated; the gel was aged at 85°C for 12 h; filtered, washed with deionized water until neutral, dried at 110°C for 24 h, and calcined at 500°C for 4 h to obtain alumina. The specific surface area of the alumina was 302 m 2 / g, pore volume was 1.5 cm 3 / g and average pore diameter of 11.0 nm.

[0144] In a hydrothermal crystallization kettle, 30 g of the alumina, 150 g of 3.0 wt% triethylamine aqueous solution were added, and treated at 70°C, 90°C, 110°C respectively for 2 h under rotating condition, filtered, the filter cake was dried at 110°C for 12 h and calcined at 550°C for 4 h, and ground for use. The specific surface area of the alumina was 315 m 2 / g, pore volume was 1.2 cm 3 / g and average pore diameter of 12.4 nm.

[0145] 10 g of the powder was taken, and an equal volume of an aqueous solution of palladium chloride-ethylenediamine complex was impregnated, wherein the Pd element loading was 0.25% mass, dried at 110°C for 24 h, calcined at 500°C for 4 h in air, and after tabletting, crushing and sieving, catalyst particles of 20-40 mesh were obtained, and recorded as catalyst Cat-9. The specific surface area of the catalyst was 304 m 2 / g, pore volume was 1.1 cm 3 / g and average pore diameter of 12.7 nm.

[0146] Example 10

[0147] The procedure of Example 1 was followed except that the concentration of triethylamine solution was 8 wt%, and other conditions were the same, and the catalyst was noted as Cat-10. The specific surface areas of the alumina raw material, support and catalyst in this example were 292, 331 and 316 m 2 / g, respectively, and the pore volumes were 1.2, 1.1 and 1.1 cm 3 / g, respectively, and the average pore diameters were 12.8, 13.3 and 13.0 nm, respectively.

[0148] The catalysts of Examples 1 and 3-10 were confirmed by XRD patterns to be γ- Al2O3.

[0149] The catalysts of Examples 1 and 3-10 were confirmed by HRSEM patterns to be Pt or Pd components dispersed in monatomic form on the surface of the support.

[0150] Comparative Example 1

[0151] The procedure of Example 2 was followed except that the hydrothermal treatment was not performed, and the catalyst was noted as Cat-DB1. The specific surface area of the catalyst Cat-DB1 was 259 m 2 / g, and the pore volume was 1.1 cm 3 / g, and the average pore diameter was 11.4 nm.

[0152] The XRD pattern is shown in Figure 3. Figure 3 shows that the crystal phase of the catalyst Cat-DB1 was γ-Al2O3.

[0153] The HRSEM pattern is shown in Figure 5. Figure 5 shows that there were Pt nanoparticles and clusters in the catalyst Cat-DB1, i.e. the Pt was not dispersed in monatomic form.

[0154] The extended X-ray absorption fine structure spectrum is shown in Figure 6. Figure 6 shows that there were Pt-Pt bonds in addition to Pt-O bonds in the catalyst Cat-DB1, indicating that there were aggregates of Pt atoms in the catalyst.

[0155] Comparative Example 2

[0156] The procedure of Example 1 was followed except that the hydrothermal treatment was performed at 60°C for 9 h (i.e. the hydrothermal treatment temperature was kept at 60°C), and other conditions were the same, and the catalyst was noted as Cat-DB2.

[0157] Comparative Example 3

[0158] The preparation process was the same as that of Example 2 except that the hydrothermal treatment was carried out using a 0.5% by mass sodium hydroxide aqueous solution instead of the triethanolamine aqueous solution, and the obtained catalyst was recorded as Cat-DB3.

[0159] Comparative Example 4

[0160] The preparation process was the same as that of Example 1 except that the hydrothermal treatment was carried out at 100°C for 9h (i.e. the hydrothermal treatment temperature was kept at 100°C unchanged), and the rest of the conditions were unchanged, and the obtained catalyst was recorded as Cat-DB4.

[0161] Comparative Example 5

[0162] The preparation process was the same as that of Example 1 except that a commercially available alumina was directly used as the carrier instead of the self-made alumina carrier to prepare the catalyst, wherein the commercially available alumina was purchased from Shanghai Aldrin Biochemical Technology Co., Ltd. (item number A102091; Primor Trace™, CAS number: 1344-28-1, nano powder, γ phase, 20 nm), and the rest of the conditions were unchanged, and the obtained catalyst was recorded as Cat-DB5.

[0163] The measurement results of the alumina carriers of the examples and comparative examples are shown in the following table.

[0164] As described above, the average coordination numbers of the catalysts of the application and the comparative catalysts were tested, and the results are shown in Table 1.

[0165] Table 1

[0166] As can be seen from Table 1, the Pt-Pt coordination numbers of the comparative catalysts Cat-DB1, Cat-DB2, Cat-DB3, Cat-DB4 and Cat-DB5 are 2.4, 0.8, 2.0, 1.1 and 2.6 respectively, which proves the existence of Pt atomic aggregates. The Pt-Pt coordination numbers of the catalysts of the examples of the application and the Pd-Pd coordination number of the catalyst Cat-9 are 0, which proves the absence of Pt atomic aggregates or Pd atomic aggregates, i.e. these catalysts are single-atom catalysts. The Pt or Pd average coordination numbers of the catalysts of the examples of the application are 5.1-5.9, all of which are Pt-O or Pd-O coordination numbers, indicating that the metal has a stronger interaction with Al2O3.

[0167] The average valence states of the catalysts of the application and the comparative catalysts before and after reduction at 350°C and 10% hydrogen / argon mixed gas (one atmosphere absolute pressure) for 4 hours were tested, and the results are shown in Table 2.

[0168] Table 2

[0169] As can be seen from Table 2, under the same reduction conditions (350°C, 10% hydrogen / argon mixture, 4 hours), the average valence of Pt of the catalysts of the present application decreased from 3.3-3.9 to 1.7-2.7, and the average valence of Pd of the catalyst Cat-9 decreased from 3.6 to 2.2. The average valence of Pt of the comparative catalysts decreased from 3.6-3.9 to 0.8-1.8. It can be seen that the active metal components of the catalysts of the present application are difficult to be reduced, indicating that the metals have stronger interaction with Al2O3.

[0170] Isobutane normalization test

[0171] The performance evaluation of the isobutane normalization catalyst was carried out on a fixed bed continuous flow reaction system. The reaction tube had a specification of 5 mm x 40 cm, the catalyst loading was 5 mL, the particle size was 20-40 mesh, and the catalyst was placed in the constant temperature zone of the furnace. The catalyst was reduced before use under the following conditions: temperature 200°C, pressure 0.5 MPa, hydrogen 10 mL / min, nitrogen 100 mL / min, and treatment time 4 h. The feed was 99% isobutane (containing 300 ppm oxygen-containing compounds (dimethyl ether), 2 ppm organic nitrogen (N-formyl morpholine), and 5 ppm sulfur-containing compounds), which was not subjected to adsorption treatment and was directly fed. The performance evaluation conditions of the catalyst were as follows: reaction temperature 470°C, pressure 2 MPa, isobutane mass space velocity 1.0 h -1 , hydrogen / isobutane feed molar ratio 0.2:1, and the reaction products were analyzed online by gas chromatography.

[0172] The performance evaluation results of the catalysts are shown in Table 3.

[0173] Figure 1 shows the performance of Cat-2 catalyst as a function of reaction time. As can be seen from Figure 1, the catalyst has excellent activity, selectivity, and stability; the average single-pass conversion of isobutane is ≥50%, the average selectivity of n-butane is ≥90%, and the average single-pass yield of n-butane is ≥45%. After 1200 hours of operation, the performance of the catalyst, including activity and selectivity, remains stable.

[0174] Figure 2 shows that after 350 hours of operation of the comparative catalyst Cat-DB1, the isobutane conversion decreased from 30.4% to 23.8%, and the n-butane selectivity decreased from 74.5% to 60.9%. It can be seen that the activity and stability of Cat-DB1 are significantly poorer than those of the single-atom catalysts of the present application.

[0175] The selectivity and conversion of the catalysts of the present application and the comparative catalysts after 24 hours and 120 hours of reaction are shown in Table 3.

[0176] Table 3

[0177] As can be seen from Figure 1, Figure 2 and Table 3, the catalyst of the present application has excellent performance in the reaction of isobutane to n-butane; the isobutane conversion of most of the catalysts of the present application is about 50%, the n-butane selectivity is about 90%, and the catalysts show excellent stability.

[0178] The spherical aberration electron microscope images of the catalyst Cat-2 before and after the catalytic reaction (reaction time 1200 hours) are shown in Figure 7. Figure 7 shows that the catalyst Cat-2 is still a single-atom catalyst after long-period reaction at high temperature.

[0179] The extended edge X-ray absorption spectrum of the catalyst Cat-2 after the catalytic reaction (reaction time 1200 hours) is shown in Figure 8. Figure 8 shows that there is no Pt-Pt bond in the catalyst Cat-2 after use, indicating that Pt is still in a single-atom state.

[0180] Butene hydrogenation performance test

[0181] The butene hydrogenation performance evaluation of the catalyst Cat-1 was carried out on a fixed bed continuous flow reaction system, the reaction tube specification was 5 mm x 40 cm, the catalyst loading was 5 mL, the particle size was 20-40 mesh, and it was placed in the constant temperature zone of the furnace. The catalyst was reduced before use, and the reduction conditions were: temperature 200°C, pressure 0.5 MPa, hydrogen 10 mL / min, nitrogen 100 mL / min, and treatment for 4 h. The feed was carbon four containing n-butene (3% n-butene, 97% isobutane), which was not treated by adsorption and was directly fed. The catalyst performance evaluation conditions were: reaction temperature 70°C, pressure 1.0 MPa, carbon four mass space velocity 1.0 h -1 , the molar ratio of hydrogen to carbon four in the feed was 0.20:1, and the reaction products were analyzed online by gas chromatography.

[0182] The results show that the butene conversion is >99% and the n-butane product selectivity is >99% at 24 hours and 120 hours of continuous operation.

[0183] It should be noted that the above-described examples are only for the purpose of explaining the present application and do not constitute any limitation on the present application. The present application has been described by referring to typical examples, but it should be understood that the words used therein are descriptive and explanatory words, rather than limiting words. Modifications can be made to the present application within the scope of the claims of the present application, and the present application can be revised within the scope and spirit of the present application. Although the present application described therein relates to specific methods, materials and examples, it does not mean that the present application is limited to the specific examples disclosed therein, on the contrary, the present application can be extended to all other methods and applications having the same function.

[0184] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. 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, and these simple modifications and combinations should also be considered as disclosed by the present application, and all fall within the protection scope of the present application.

Claims

1. A catalyst characterized in that, The catalyst comprises: an Al2O3 support and an active metal component M, wherein the content of M element is 0.05-1.0% based on the total weight of the catalyst, wherein the active metal component M is loaded on the surface of the support in the form of single atom, wherein the average coordination number of M atom is 5.0-6.0, preferably 5.2-5.6, and the average valence of M atom is +3.0 to +4.0, preferably +3.5 to +3.9, and wherein the M is Pd or Pt, preferably Pt.

2. The catalyst of claim 1, wherein, After treatment at 350℃ under H2 / Ar (v / v=1:9) atmosphere at normal pressure for 4 hours, the average valence of M atom in the catalyst is +1.6 to +3.0, preferably +2.0 to +3.0, more preferably +2.0 to +2.4; Preferably, the ratio of the average valence of M atom after treatment to the average valence of M atom before treatment is greater than or equal to 0.50 to less than or equal to 0.75, preferably greater than or equal to 0.51 to less than or equal to 0.64; and / or Preferably, the difference between the average valence of M atom before treatment and the average valence of M atom after treatment is greater than or equal to 1.0 and less than or equal to 2.0, preferably greater than or equal to 1.3 and less than or equal to 1.

9.

3. The catalyst according to claim 1 or 2, wherein, the Al2O3 is γ-Al2O3; and / or the content of M element in the catalyst is 0.1-0.25% by weight based on the total weight of the catalyst; and / or The specific surface area of the catalyst is 200 to 320 m 2 / g, preferably 290 to 320 m 2 / g; the pore volume is 0.6 to 1.5 cm 3 / g, preferably 0.9 to 1.1 cm 3 / g; and the average pore diameter is 5 to 20 nm, preferably 11 to 15 nm.

4. The catalyst according to any one of claims 1-3, wherein, the catalyst does not comprise active metal component other than M; and / or wherein the support of the catalyst consists of Al2O3; and / or wherein the catalyst consists of the support Al2O3 and the active metal component M; and / or wherein there is no M-M bond in the catalyst.

5. The catalyst of any one of claims 1-4, wherein, The catalyst is a reforming catalyst, preferably an isoparaffin normalization reaction catalyst, more preferably a C4-C6 isoparaffin normalization catalyst, further more preferably an isobutane normalization catalyst.

6. Process for the preparation of the catalyst according to any one of claims 1 to 5, characterized in that, The method comprises: (a) gradient temperature hydrothermal treatment of an alumina raw material, and drying and calcination to prepare an alumina support; (b) contacting a solution containing M with the alumina support to load, and drying and calcination to provide the catalyst; preferably, the loading is carried out by isovolume impregnation.

7. The method of claim 6, wherein, The specific surface area of the alumina raw material is 190 to 320 m 2 / g, preferably 250 to 320 m 2 / g, preferably 1.1 to 1.5 cm 3 / g, preferably 1.1 to 1.5 cm 3 / g, and the average pore diameter is 5 to 15 nm, preferably 9 to 15 nm; and / or The specific surface area of the alumina support is 220 to 350 m 2 / g, preferably 300 to 350 m 2 / g, preferably 0.9 to 1.3 cm 3 / g, preferably 0.9 to 1.3 cm 3 / g, and the average pore diameter do is 5 to 20 nm, preferably 9 to 15 nm; and / or The BJH adsorption median pore diameter of the alumina support is d1 and the BJH adsorption most probable pore diameter is d2, wherein d0 / d1 is 0.90-1.20 and d0 / d2 is 0.90-1.25, preferably d0 / d1 is 0.90-1.15 and d0 / d2 is 0.90-1.

20.

8. The method of claim 6 or 7, wherein, The hydrothermal treatment uses an aqueous organic base solution, wherein the organic base is an amine; and / or wherein the concentration of the aqueous organic base solution is 0.5-10% by weight, preferably 1-5% by weight; and / or wherein the weight ratio of the aqueous organic base solution to the solid alumina is (3:1)-(10:1), preferably (4:1)-(7:1).

9. The method according to claim 8, wherein the amine is selected from one or more of aliphatic amines, alcohol amines, alicyclic amines and aromatic amines, more preferably from one or more of pyridine, cyclohexylamine, piperidine, morpholine, pyrrole, tetrahydropyrrole, primary amine NH2R1, secondary amine NHR1R2, tertiary amine NR1R2R3, wherein the pyridine, cyclohexylamine, piperidine, morpholine, pyrrole and tetrahydropyrrole are optionally substituted with a substituent selected from methyl, ethyl, n-propyl, i-propyl, butyl, and wherein R1, R2 and R3 are each independently methyl, ethyl, hydroxymethyl, hydroxyethyl, hydroxypropyl, n-propyl, i-propyl, butyl, phenyl or benzyl; more preferably the amine is selected from trimethylamine, triethylamine, triethanolamine, diisopropylamine, cyclohexylamine, piperidine, pyridine and aniline.

10. The method according to any one of claims 6-9, wherein the gradient temperature treatment has a starting temperature of 50-90 °C and an ending temperature of 90-130 °C, and the gradient temperature treatment comprises at least 2 gradients, preferably 3-10 gradients, wherein the temperature difference between each of the two adjacent gradients is independently 5-40 °C, preferably independently 10-30 °C; more preferably, the gradient temperature step of the hydrothermal treatment comprises: at temperatures of T °C, (T+20) °C and (T+40) °C for 0.5-10 h, preferably 1-4 h, wherein T is 50-85; and / or wherein the hydrothermal treatment is for a time of 1-120 h, preferably 2-72 h, more preferably 3-48 h.

11. The method of any of claims 6-10, wherein, The method further comprises preparing the alumina raw material by an aluminum salt precipitation method; preferably, in the aluminum salt precipitation method, the aluminum salt is one or more of aluminum nitrate and its hydrate, aluminum sulfate and its hydrate, and combinations thereof, the precipitant is concentrated ammonia water with a mass concentration of 25-28%, and the precipitation pH is 8.5-9.

0.

12. The method according to any one of claims 6-11, wherein, the drying conditions comprise an air atmosphere, a drying temperature of 100-200 °C, and a drying time of 1-24 h; and / or the calcination conditions comprise an air atmosphere, a calcination temperature of 450-580 °C, and a constant temperature time of 3-8 h.

13. A method for preparing normal alkanes from isomeric alkanes, comprising normalizing isomeric alkanes in the presence of the catalyst according to any one of claims 1-5 to obtain normal alkanes; preferably, the isomeric alkanes are selected from C4-C6 isomeric alkanes, preferably isobutane.

14. Use of the catalyst according to any one of claims 1-5 in a reforming reaction, preferably in an isomeric alkane normalizing reaction; Preferably, the conditions for the isomeric alkane normalisation reaction comprise: The reaction temperature is 350-550°C, the pressure is 1-3 MPa, the WHSV of isomeric alkanes is 0.5-3 h -1 and the molar ratio of hydrogen / isomeric alkanes is 0.03-1.0; and / or preferably, the isomeric alkanes are selected from C4-C6 isomeric alkanes, preferably isobutane.

15. The method according to claim 13 or the use according to claim 14, wherein, After the catalyst is used for 1200 hours at 350-550 °C, there is no M-M bond in the catalyst.

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