Supported catalyst, method of preparation and method for catalytic reforming of naphtha

Abstract

The application discloses a supported catalyst, a preparation method and a naphtha catalytic reforming method. The supported catalyst comprises an alumina carrier, Pt and an auxiliary metal, the auxiliary metal is Ge, Ga, Sn, Zn or In, and the Pt and the auxiliary metal are dispersed on the alumina carrier in the form of bimetallic alloy sub-nanometer clusters. The preparation method of the supported catalyst comprises the following steps: (1) adding a Pt precursor into a reducing organic solvent to obtain a first solution; (2) adding an auxiliary metal precursor into the reducing organic solvent to obtain a second solution; and (3) simultaneously adding the first solution and the second solution into the reducing organic solvent to obtain a mixed solution. In the supported catalyst, the Pt and the auxiliary metal are dispersed on the surface of the alumina carrier in the form of bimetallic alloy sub-nanometer clusters, the supported catalyst has good aromatic hydrocarbon selectivity and carbon deposition resistance when used for a naphtha catalytic reforming reaction, and the liquid product yield can be obviously improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalytic reforming, in particular to a supported catalyst, a preparation method and a method for catalytic reforming of naphtha. BACKGROUND

[0002] Catalytic reforming can process hydrocarbon molecules in naphtha into aromatics, hydrogen and high-octane gasoline components, and is one of the main technologies in the modern petrochemical industry. The catalytic reforming process is widely used to improve the quality of heavy gasoline, and hydrocarbons containing 6-12 carbon atoms per molecule in heavy gasoline (paraffins and naphthenes) are converted into aromatics or branched alkanes in the reforming process. The reforming reaction is carried out at high temperature (500℃), low to medium pressure (3.5×10 5 ~ 25×10 5 Pa) and in the presence of a catalyst. The catalytic reformate can be used to improve the octane number of the oil component, and the reformate mainly consists of C5 + hydrocarbon compounds (containing at least 5 carbon atoms). The process also produces H2, fuel gas (formed by C1-C2 hydrocarbons) and liquefied gas (formed by C3-C4 hydrocarbons). In addition, coke is also formed by the condensation of aromatic rings and deposited on the active sites of the catalyst.

[0003] During the catalytic reforming process, competitive reactions occur simultaneously, including the dehydrogenation of cyclohexane to aromatics, the dehydrogenation isomerization of alkylcyclohexane to aromatics, and the dehydrogenation cyclization of cycloalkanes to aromatics. In these reactions, the production of light hydrocarbon gas due to hydrogenation cracking will reduce the yield of gasoline, and the coking reaction will accelerate the deactivation rate of the catalyst, and frequent catalyst regeneration will increase the operating cost of the device. Therefore, developing a catalytic reforming catalyst with high selectivity and low carbon deposition rate has always been the goal of people.

[0004] In industrial reforming catalysts, the platinum content is generally a few parts per thousand. In order to provide sufficient metal centers, the dispersion state of platinum on Al2O3 is the key to determining the performance of the catalyst. In order to improve the performance of Pt / Al2O3 catalyst, other metals are often used as additives to modify the metal centers and acid centers of the catalyst, further improve the activity, stability and selectivity of the catalyst, and further prolong the service life of the catalyst. The influence and mechanism of the additive on the dispersion state, microstructure, metal function and support acidity function of platinum are key scientific problems. How to design a naphtha catalytic reforming catalyst to improve the catalytic selectivity of Pt / Al2O3 catalyst and reduce the carbon deposition rate, avoid frequent regeneration of the catalyst due to carbon deposition during use or eventually lead to deactivation is a technical problem that needs to be solved at present. SUMMARY

[0005] The application provides a supported catalyst, a preparation method and a naphtha catalytic reforming method to improve the catalytic selectivity of a catalytic reforming catalyst and the anti-coking performance of the catalyst.

[0006] In a first aspect, the application provides a supported catalyst, comprising an alumina carrier, Pt and an auxiliary metal, wherein the auxiliary metal is Ge, Ga, Sn, Zn or In, and the Pt and the auxiliary metal are dispersed on the alumina carrier in the form of bimetallic alloy sub-nanometer clusters.

[0007] Optionally, the supported catalyst further comprises Cl, and the supported catalyst comprises 0.01-5 wt% Pt, 0.01-10.0 wt% auxiliary metal and 0.1-5 wt% Cl, based on the weight of the alumina carrier.

[0008] Optionally, the atomic ratio of Pt to the auxiliary metal is (0.01-20):1, the particle size of the bimetallic alloy sub-nanometer clusters is 0.4-1.7 nm, and the number of particles with a particle size of 0.6-1.2 nm accounts for 80-100%, and preferably, the particle size of the bimetallic alloy sub-nanometer clusters is 1 nm.

[0009] In a second aspect, the application provides a method for preparing the supported catalyst, comprising the following steps: (1) adding a Pt precursor into a reducing organic solvent to obtain a first solution; (2) adding an auxiliary metal precursor into a reducing organic solvent to obtain a second solution; (3) simultaneously adding the first solution obtained in step (1) and the second solution obtained in step (2) into a reducing organic solvent, adjusting the pH value of the solution to be alkaline, and then heating to obtain a mixed solution; (4) adding an alumina carrier into the mixed solution obtained in step (3) for impregnation, drying and calcination to obtain an intermediate product; and (5) performing hydrochloric activation and reduction on the intermediate product obtained in step (4).

[0010] Optionally, in step (1), the adding of the Pt precursor into the reducing organic solvent comprises adding the Pt precursor into a first part of the reducing organic solvent and then mixing with a second part of the reducing organic solvent, the Pt precursor is one or more than two of chloroplatinic acid, ammonium chloroplatinate, bromoplatinic acid, platinum chloride, tetrahydrate of platinum chloride, dichlorocarbonylplatinum dichloride, dinitrodiamino platinum, tetranitroplatinic acid and platinum acetylacetonate, the reducing organic solvent is one or more than two of methanol, ethylene glycol and formaldehyde, and the concentration of Pt in the first solution is 0.5-5 mg / mL.

[0011] Optionally, in step (2), the assistant metal precursor is one of germanium nitrate, gallium nitrate, zinc nitrate, tin tetrachloride, stannous chloride and indium nitrate; the concentration of the assistant metal in the second solution is 0.5-5 mg / mL; the reducing organic solvent is one or more than two of methanol, ethylene glycol and formaldehyde.

[0012] Optionally, in step (3), the speed of adding the first solution and the second solution into the reducing organic solvent is such that the atomic ratio of Pt to the assistant metal added into the reducing organic solvent is (0.01-20):1; the reducing organic solvent is one or more than two of methanol, ethylene glycol and formaldehyde; preferably, in the mixed solution, the concentration of Pt and the assistant metal is independently 0.1-2.5 mg / mL.

[0013] Optionally, in step (3), the pH value of the solution is adjusted to 8-14 by adding a base solution into the solution.

[0014] Optionally, in step (3), the base solution is selected from ammonia, urea solution, sodium hydroxide solution or potassium hydroxide solution; preferably, the base solution is ammonia; preferably, the concentration of the ammonia is 5-30 wt%.

[0015] Optionally, in step (4), the pore volume of the alumina carrier is 0.3-1.2 mL / g, and the specific surface area is 50-300 m 2 / g; the drying temperature is 50-300℃, and the time is 2-48 h.

[0016] Optionally, in step (5), the hydrochloric activation includes heating the intermediate product from step (4) in an air containing HCl and H2O; the molar ratio of H2O to HCl in the air containing HCl and H2O is (10-100):1; the heating temperature is 370-700℃, and the time is 1-16 h; and / or, the reduction temperature is 250-650℃, and the time is 0.5-16 h, and the reduction is carried out in a reduction atmosphere containing hydrogen or carbon monoxide, and the volume fraction of hydrogen or carbon monoxide is 10-100%.

[0017] In a third aspect, the present application provides a method for catalytic reforming of naphtha, comprising: contacting naphtha with a supported catalyst under catalytic reforming reaction conditions to carry out reaction, wherein the supported catalyst is the above-mentioned supported catalyst or is prepared by the above-mentioned method.

[0018] Optionally, the catalytic reforming reaction conditions include: the temperature is 360-600℃, the pressure is 0.1-1.0 MPa, the liquid feed volume space velocity is 1-20 h -1hydrogen / hydrocarbon volume ratio of 500-2000.

[0019] Optionally, the naphtha is selected from at least one of straight-run naphtha, hydrocracking naphtha, coking naphtha, catalytic cracking naphtha and ethylene cracking naphtha; preferably, the naphtha contains paraffins, naphthenes and aromatics; preferably, the naphtha contains hydrocarbons with carbon number of 5-12.

[0020] Advantages:

[0021] In the supported catalyst, Pt and the promoter metal are dispersed on the surface of the alumina carrier in the form of bimetallic alloy sub-nanometer clusters, and when used for catalytic reforming of naphtha, the supported catalyst has good aromatic selectivity and anti-coking capacity, and can significantly improve the yield of liquid products. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 HAADF-STEM image of the supported catalyst prepared in Example 1.

[0023] Figure 2 Particle size size distribution diagram of the Pt and the bimetallic alloy sub-nanometer clusters of the promoter metal in the supported catalyst prepared in Example 1.

[0024] Figure 3 HAADF-STEM image of the catalyst prepared in Comparative Example 2. DETAILED DESCRIPTION

[0025] The application will be further described below in detail by means of the accompanying drawings and examples. Through these descriptions, the features and advantages of the application will become more apparent.

[0026] The term "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations. Unless specifically stated otherwise, the drawings are not drawn to scale and are merely intended to conceptually illustrate aspects of the embodiments.

[0027] In addition, the technical features involved in different embodiments of the application described below can be combined with each other as long as there is no conflict.

[0028] In a first aspect, the application provides a supported catalyst, comprising an alumina carrier, Pt and a promoter metal, the promoter metal being Ge, Ga, Sn, Zn or In, and Pt and the promoter metal being dispersed on the alumina carrier in the form of bimetallic alloy sub-nanometer clusters.

[0029] It should be noted that the supported catalyst of the present application can be used in catalytic reforming reaction of naphtha. In the supported catalyst of the present application, Pt and the auxiliary metal form an alloy, and when the auxiliary metal is incorporated into the crystal lattice of Pt, the electronic structure and geometric structure of Pt can be adjusted; in the electronic structure, there is electron transfer between the two metals, which changes the electronic environment of Pt; in the geometric structure, the addition of the auxiliary metal can change the distance between Pt atoms, and improve the dispersion of Pt atoms. Pt and the auxiliary metal are dispersed on the alumina carrier in the form of bimetallic alloy sub-nanometer clusters, which further improves the dispersion of Pt atoms. By improving the dispersion of Pt atoms, the aromatic selectivity of the catalyst can be effectively improved.

[0030] According to an embodiment, the supported catalyst further comprises Cl; the supported catalyst comprises 0.01-5wt% of Pt, 0.01-10.0wt% of the auxiliary metal, and 0.1-5wt% of Cl, based on the weight of the alumina carrier. Preferably, the content of Pt is 0.02-1wt%.

[0031] It should be noted that in this embodiment, Pt as a metal center can play a hydrogenation-dehydrogenation function, Cl as an acid center can play an isomerization acid function, the auxiliary metal and Pt form an alloy to affect the electronic and geometric structure of Pt, change the distance between Pt atoms, and further improve the dispersion of Pt atoms, thereby effectively improving the aromatic selectivity of the catalyst. In addition, in this embodiment, the catalyst still has very good catalytic performance, including good aromatic selectivity and low carbon deposition rate, while Pt maintains a low content.

[0032] As a preferred embodiment, the atomic ratio of Pt to the auxiliary metal is (0.01-20):1, preferably (0.5-10):1; the particle size of the bimetallic alloy sub-nanometer clusters is 0.4-1.7nm, and the number of particles with a particle size of 0.6-1.2nm accounts for 80-100%; preferably, the particle size of the bimetallic alloy sub-nanometer clusters is about 1nm.

[0033] It should be noted that in this embodiment, by controlling the atomic ratio of Pt to the auxiliary metal and the particle size of the bimetallic alloy sub-nanometer clusters, the bimetallic alloy sub-nanometer clusters of Pt and the auxiliary metal are loaded on the surface of the alumina carrier in an optimal manner, so that the catalyst has better catalytic performance.

[0034] In a second aspect, the present application provides a method for preparing the supported catalyst, comprising the following steps: (1) adding a Pt precursor into a reducing organic solvent to obtain a first solution; (2) adding an auxiliary metal precursor into a reducing organic solvent to obtain a second solution; (3) simultaneously adding the first solution obtained in step (1) and the second solution obtained in step (2) into a reducing organic solvent, adjusting the pH value of the solution to be alkaline, and then heating to obtain a mixture; (4) adding an alumina carrier into the mixture obtained in step (3) to perform impregnation, drying and calcination to obtain an intermediate product; and (5) performing water-chlorine activation and reduction on the intermediate product obtained in step (4).

[0035] It should be noted that in the preparation method of the present application, the Pt and the auxiliary metal are respectively added into the reducing organic solvent to be stirred, dissolved and mixed uniformly to obtain the first solution and the second solution, respectively, and then the first solution and the second solution are slowly dropped into the reducing organic solvent, the pH value of the mixture is adjusted to be alkaline during the mixing process, so that the Pt and the auxiliary metal form bimetallic alloy sub-nanometer clusters existing in the mixture, and then the catalyst with the Pt and the auxiliary metal bimetallic alloy sub-nanometer clusters supported on the surface of the alumina carrier is obtained through impregnation and subsequent treatment. In the present application, the reducing organic solvent mainly plays a role in reducing the metal ions in the solution into metal atoms, the metal atoms are aggregated into nuclei, and finally the bimetallic sub-nanometer clusters are formed.

[0036] In step (3), when the first solution and the second solution are simultaneously added into the reducing organic solvent, the pH value of the mixed solution is adjusted to be alkaline at the same time, that is, the pH value of the mixed solution is adjusted in real time to be alkaline during the process of adding the first solution and the second solution into the reducing organic solvent.

[0037] The preparation method of the present application can reduce the content or dosage of noble metal, maximize the combination degree of Pt and auxiliary metal, make them form an alloy, and effectively improve the performance of the catalyst in the reaction.

[0038] According to an embodiment, in step (1), the Pt precursor is added into a first part of the reducing organic solvent, and then mixed with a second part of the reducing organic solvent to obtain the first solution. Alternatively, the Pt precursor is directly added into the reducing organic solvent to obtain the first solution. The concentrations of the first solutions obtained by the above two methods can be equal. The Pt precursor is one or more than two of chloroplatinic acid, ammonium chloroplatinate, bromoplatinic acid, platinum chloride, platinum tetrachloride hydrate, dichlorocarbonylplatinum dichloride, dinitrodiamino platinum, tetranitroplatinic acid and platinum acetylacetone; the reducing organic solvent is one or more than two of methanol, ethylene glycol and formaldehyde; and the concentration of Pt in the first solution is 0.5-5 mg / mL.

[0039] As a preferred embodiment, the reducing organic solvent is ethylene glycol. The concentration of Pt can refer to the concentration of Pt in terms of mass.

[0040] According to one embodiment, in step (2), the assistant metal precursor is one of germanium nitrate, gallium nitrate, zinc nitrate, tin tetrachloride, stannous chloride and indium nitrate; the concentration of the assistant metal in the second solution is 0.5-5 mg / mL; and the reducing organic solvent is one or more than two of methanol, ethylene glycol and formaldehyde. The concentration of the assistant metal in the second solution can refer to the concentration of the assistant metal in terms of mass.

[0041] As a preferred embodiment, the reducing organic solvent is ethylene glycol.

[0042] As a preferred embodiment, in step (3), the first solution and the second solution are added to the reducing organic solvent at a speed such that the atomic ratio of Pt to the assistant metal added to the reducing organic solvent is (0.01-20):1; preferably, in the mixed solution, the concentration of Pt and the assistant metal is independently 0.1-2.5 mg / mL. The concentration of the metal can refer to the concentration of the metal in terms of mass.

[0043] It should be noted that as a specific embodiment, the first solution and the second solution with the above-mentioned concentrations can be prepared first, and the same volume of the first solution and the second solution is taken, and the atomic ratio of Pt to the assistant metal in the taken first solution and second solution is (0.01-20):1; then, the taken first solution and second solution are added dropwise to the reducing organic solvent, and the two solutions can be added dropwise at the same adding speed, and the volume of the two solutions added to the reducing organic solvent per unit time is substantially equal, so that the atomic ratio of Pt to the assistant metal in the first solution and the second solution added to the reducing organic solvent per unit time can be kept as (0.01-20):1, i.e. from the beginning of the dropwise addition to the end of the dropwise addition of the taken two solutions, the atomic ratio of Pt to the assistant metal in the mixed solution can be kept as (0.01-20):1.

[0044] According to one embodiment, in step (3), the pH value of the solution is adjusted to 8-14 by adding a base solution to the solution.

[0045] The base solution is selected from ammonia water, urea solution, sodium hydroxide solution or potassium hydroxide solution. Preferably, the base solution is ammonia water. Preferably, the concentration of the ammonia water is 5-30 wt%. The reducing organic solvent is preferably ethylene glycol.

[0046] It should be noted that the isoelectric point is adjusted to 8-14 in step (3) to make the metal more easily adsorbed on the carrier in the form of clusters.

[0047] According to one embodiment, in step (3), the heating includes heating to 120-180℃ and stirring for 1-6h, and then cooling to room temperature; step (3) is carried out in an inert atmosphere; the inert atmosphere is one or more than two of argon, nitrogen and helium.

[0048] It should be noted that in step (3), the two solutions are mixed by the above-mentioned mixing method, and then the pH value of the solution is adjusted by the above-mentioned method, and heating, stirring and cooling are carried out, so that Pt and the auxiliary metal form bimetallic alloy sub-nanometer clusters in the mixed solution.

[0049] According to one embodiment, in step (4), the pore volume of the alumina carrier is 0.3-1.2g / mL, and the specific surface area is 50-300m 2 / g. The impregnation can be carried out in a sealed container, the impregnation temperature is 10-80℃, and the impregnation time is 10-100h. After impregnation, drying can be carried out, the drying temperature is 50-300℃, and the time is 2-48h.

[0050] It should be noted that the Pt and the auxiliary metal are loaded or electrostatically adsorbed on the alumina carrier in the form of bimetallic alloy sub-nanometer clusters by impregnation in step (4).

[0051] According to one embodiment, in step (5), the water-chlorine activation includes placing the intermediate product from step (4) in an air containing HCl and H2O for heating. The molar ratio of H2O to HCl in the air containing HCl and H2O is (10-100):1. The heating temperature is 370-700℃, and the time is 1-16h. After water-chlorine activation, reduction can be carried out, the reduction temperature is 250-650℃, and the time is 0.5-16h. The reduction is carried out in a reducing atmosphere containing hydrogen or carbon monoxide, and the volume fraction of hydrogen or carbon monoxide is 10-100%.

[0052] It should be noted that water-chlorine activation by placing the intermediate product in an air containing HCl and H2O can increase the chlorine content and acid strength of the catalyst, and thus the catalyst has better catalytic selectivity.

[0053] In a third aspect, the present application provides a method for catalytic reforming of naphtha, which comprises: contacting naphtha with the supported catalyst under catalytic reforming reaction conditions for reaction, wherein the supported catalyst is the supported catalyst described above or prepared by the preparation method described above.

[0054] According to one embodiment, the catalytic reforming reaction conditions include: temperature of 360-600℃, pressure of 0.1-1.0 MPa, liquid feed volume space velocity of 1-20 h -1 , and hydrogen / hydrocarbon volume ratio of 500-2000.

[0055] It should be noted that the hydrogen / hydrocarbon volume ratio can also be 200-2000. In the naphtha catalytic reforming method of the present application, the above supported catalyst is used as the catalyst, and the catalytic reforming reaction is carried out under the above conditions. During the reaction, the catalyst structure is stable and not easy to agglomerate, the catalyst has good selectivity and carbon deposition resistance, and the liquid product yield of the reaction can be obviously improved.

[0056] According to one embodiment, the naphtha is selected from at least one of straight-run naphtha, hydrocracking naphtha, coking naphtha, catalytic cracking naphtha and ethylene cracking naphtha; preferably, the naphtha contains paraffins, naphthenes and aromatics, and the carbon number of the hydrocarbons contained in the naphtha is 5-12.

[0057] The initial boiling point of the naphtha determined according to the method of ASTM D-86 can be 40-100℃, preferably 70-90℃, and the final boiling point can be 140-220℃, preferably 160-180℃. The naphtha catalytic reforming method of the present application is preferably carried out in a sulfur-free or low-sulfur environment, and the sulfur content of the naphtha can be not higher than 1.0 μg / g, preferably not higher than 0.5 μg / g. In order to achieve the required sulfur content, the naphtha can be desulfurized by various desulfurization methods before catalytic reforming, including adsorption desulfurization and catalytic desulfurization, which are well known to those skilled in the art and will not be described here.

[0058] The present application is further illustrated in detail by the following examples. The reagents used in the following examples are commercially available.

[0059] Preparation Example of Carrier

[0060] Mix 137.4 g of pseudo-boehmite powder (produced by Condea Company in Germany, trademark SB, alumina content of 72.8 wt%), 350 g of deionized water, stir for 0.5 h, add 14 g of nitric acid solution with a concentration of 22 wt% drop by drop, stir at 20℃ for 2 h, add 30 g of kerosene and 3 g of fatty alcohol polyoxyethylene ether, and drop into a ball in an oil ammonia column. The wet ball is solidified in ammonia water for 1 h, then filtered, washed with deionized water, dried at 60℃ for 6 h, dried at 120℃ for 10 h, and calcined at 600℃ for 4 h to obtain a γ-Al2O3 carrier. The specific surface area of the carrier is tested by N2 adsorption (BET) to be 210 m 2 / g, and the pore volume is 0.6 mL / g.

[0061] Example 1

[0062] Under Ar atmosphere, 22.2 mL of chloroplatinic acid ethylene glycol solution with Pt content of 4.5 mg / mL was mixed with 100 mL of ethylene glycol (analytical pure) to obtain solution A, with Pt concentration of 0.82 mg / mL; under Ar atmosphere, 115.6 mg of SnCl2·2H2O was dissolved in 100 mL of ethylene glycol solution to obtain solution B, with Sn concentration of 0.61 mg / mL; under inert atmosphere of Ar, solutions A and B were simultaneously added dropwise into 100 mL of ethylene glycol, and the pH was adjusted to 12 with 10 wt% ammonia solution; after the dropwise addition of solutions A and B was completed, the mixture was stirred for 30 min and then transferred into an oil bath at 150°C for stirring for 3 h; the mixture was cooled to room temperature under inert atmosphere, and the prepared γ-Al2O3 carrier was added into the mixture, which was stirred for 3 h until uniform mixing; the catalyst was washed and filtered at room temperature, and the obtained product was transferred into a 120°C oven for drying for 12 h, followed by calcination at 500°C in air atmosphere for 3 h; the sample was subjected to hydrochloric water activation by passing air containing HCl and water at 450°C for 4 h, and then reduced in hydrogen at 450°C for 4 h to obtain the reduced catalyst A, and the metal component content in the catalyst was determined by X-ray fluorescence method.

[0063] Example 2

[0064] Under Ar atmosphere, 22.2 mL of chloroplatinic acid ethylene glycol solution with Pt content of 4.5 mg / mL was mixed with 100 mL of ethylene glycol (analytical pure) to obtain solution A, with Pt concentration of 0.82 mg / mL; under Ar atmosphere, 115.6 mg of SnCl2·2H2O was dissolved in 100 mL of ethylene glycol solution to obtain solution B, with Sn concentration of 0.61 mg / mL; under inert atmosphere of Ar, solutions A and B were simultaneously added dropwise into 100 mL of ethylene glycol, and the pH was adjusted to 12 with 10 wt% ammonia solution; after the dropwise addition of solutions A and B was completed, the mixture was stirred for 30 min and then transferred into an oil bath at 150°C for stirring for 3 h; the mixture was cooled to room temperature under inert atmosphere, and the prepared γ-Al2O3 carrier was added into the mixture, which was stirred for 3 h until uniform mixing; the catalyst was washed and filtered at room temperature, and the obtained product was transferred into a 120°C oven for drying for 12 h, followed by calcination at 500°C in air atmosphere for 3 h; the sample was subjected to hydrochloric water activation by passing air containing HCl and water at 450°C for 4 h, and then reduced in hydrogen at 450°C for 4 h to obtain the reduced catalyst A, and the metal component content in the catalyst was determined by X-ray fluorescence method.

[0065] Example 3

[0066] Under Ar atmosphere, 22.2 mL of chloroplatinic acid ethylene glycol solution with Pt content of 4.5 mg / mL was mixed with 100 mL of ethylene glycol (analytical pure) to obtain solution A, with Pt concentration of 0.82 mg / mL; under Ar atmosphere, 346.8 mg of SnCl2·2H2O was dissolved in 100 mL of ethylene glycol solution to obtain solution B, with Sn concentration of 1.83 mg / mL; solutions A and B were simultaneously added slowly into 100 mL of ethylene glycol, and the pH was adjusted to 12 with 10 wt% ammonia water; after the addition of solutions A and B was completed, the mixture was stirred for 30 min, and then transferred into an oil bath at 150°C and stirred for 3 h; the mixture was cooled to room temperature under inert atmosphere, and then γ-Al2O3 carrier prepared above was added into the mixture and stirred for 3 h until uniform; the catalyst was washed and filtered at room temperature, and then the obtained product was transferred into a 120°C oven and dried for 12 h, followed by calcination at 500°C in air for 3 h; the sample was activated by water and chlorine at 450°C for 4 h, and then reduced in hydrogen at 450°C for 4 h to obtain reduced catalyst C; the metal component content in the catalyst was determined by X-ray fluorescence method.

[0067] Example 4

[0068] Under Ar atmosphere, 22.2 mL of chloroplatinic acid ethylene glycol solution with Pt content of 4.5 mg / mL was mixed with 100 mL of ethylene glycol (analytical pure) to obtain solution A, with Pt concentration of 0.82 mg / mL; under Ar atmosphere, 346.8 mg of SnCl2·2H2O was dissolved in 100 mL of ethylene glycol solution to obtain solution B, with Sn concentration of 1.83 mg / mL; solutions A and B were simultaneously added slowly into 100 mL of ethylene glycol, and the pH was adjusted to 12 with 10 wt% ammonia water; after the addition of solutions A and B was completed, the mixture was stirred for 30 min, and then transferred into an oil bath at 150°C and stirred for 3 h; the mixture was cooled to room temperature under inert atmosphere, and then γ-Al2O3 carrier prepared above was added into the mixture and stirred for 3 h until uniform; the catalyst was washed and filtered at room temperature, and then the obtained product was transferred into a 120°C oven and dried for 12 h, followed by calcination at 500°C in air for 3 h; the sample was activated by water and chlorine at 450°C for 4 h, and then reduced in hydrogen at 450°C for 4 h to obtain reduced catalyst C; the metal component content in the catalyst was determined by X-ray fluorescence method.

[0069] Example 5

[0070] Under Ar atmosphere, 22.2 mL of chloroplatinic acid ethylene glycol solution with Pt content of 4.5 mg / mL was mixed with 100 mL of ethylene glycol (analytical pure) to obtain solution A, the concentration of Pt was 0.82 mg / mL; under Ar atmosphere, 115.6 mg of SnCl2·2H2O was dissolved in 100 mL of ethylene glycol solution to obtain solution B, the concentration of Sn was 0.61 mg / mL; under inert atmosphere of Ar, solution A and solution B were simultaneously added to 100 mL of ethylene glycol, and 10 wt% ammonia solution was used to adjust the pH to 14; after the addition of solution A and solution B was completed, the mixture was continuously stirred for 30 minutes until it was uniformly mixed, then the mixture was transferred to an oil bath pot and stirred at 150℃ for 3 h, and then it was cooled to room temperature under inert atmosphere; the prepared γ-Al2O3 carrier was added to the mixture, stirred for 3 h until it was uniformly mixed, then the catalyst was washed and filtered at room temperature, and then the obtained product was transferred to a 120℃ oven for drying for 12 h, and then it was calcined at 500℃ in air atmosphere for 3 h; the sample was subjected to hydrochloric water activation by introducing air containing HCl and water at 450℃ for 4 h, and then it was reduced in hydrogen at 450℃ for 4 h to obtain the reduced catalyst E, and the metal component content in the catalyst was determined by X-ray fluorescence method.

[0071] Example 6

[0072] Under Ar atmosphere, 22.2 mL of chloroplatinic acid ethylene glycol solution with Pt content of 4.5 mg / mL was mixed with 100 mL of ethylene glycol (analytical pure) to obtain solution A, the concentration of Pt was 0.82 mg / mL; under Ar atmosphere, 115.6 mg of SnCl2·2H2O was dissolved in 100 mL of ethylene glycol solution to obtain solution B, the concentration of Sn was 0.61 mg / mL; under inert atmosphere of Ar, solution A and solution B were simultaneously added to 100 mL of ethylene glycol, and 10 wt% ammonia solution was used to adjust the pH to 14; after the addition of solution A and solution B was completed, the mixture was continuously stirred for 30 minutes until it was uniformly mixed, then the mixture was transferred to an oil bath pot and stirred at 150℃ for 3 h, and then it was cooled to room temperature under inert atmosphere; the prepared γ-Al2O3 carrier was added to the mixture, stirred for 3 h until it was uniformly mixed, then the catalyst was washed and filtered at room temperature, and then the obtained product was transferred to a 120℃ oven for drying for 12 h, and then it was calcined at 500℃ in air atmosphere for 3 h; the sample was subjected to hydrochloric water activation by introducing air containing HCl and water at 450℃ for 4 h, and then it was reduced in hydrogen at 450℃ for 4 h to obtain the reduced catalyst E, and the metal component content in the catalyst was determined by X-ray fluorescence method.

[0073] Comparative Example 1

[0074] Under the protection of Ar atmosphere, 22.2 mL of chloroplatinic acid ethylene glycol solution with a platinum content of 4.5 mg / mL was mixed with 100 mL of ethylene glycol (analytical pure), and the pH was adjusted to 12 with a 10 wt% ammonia solution. The mixture was transferred to an oil bath and stirred at 150°C for 3 h. After being cooled to room temperature under the protection of inert atmosphere, the γ-Al2O3 carrier prepared above was added to the mixture, and stirred for 3 h until the mixture was uniformly mixed. The catalyst was then washed and filtered at room temperature, and the obtained product was transferred to a 120°C oven for drying for 12 h, followed by calcination at 500°C in air for 3 h. The sample was then activated by water and chlorine at 450°C for 4 h in air containing HCl and water, and then reduced in hydrogen at 450°C for 4 h to obtain the reduced catalyst a.

[0075] Comparative Example 2

[0076] The specific preparation method includes the following steps: 22.2 mL of chloroplatinic acid aqueous solution with a platinum content of 4.5 mg / mL was mixed with 100 mL of deionized water, and after being uniformly mixed, 115.6 mg of SnCl2·2H2O was added to obtain a Sn concentration of 0.61 mg / mL. After being uniformly mixed by continuing to stir for 30 min, the γ-Al2O3 carrier prepared above was added to the mixture, and after being uniformly mixed by stirring, the filtrate was evaporated to dryness. The sample was dried at 120°C for 12 h, followed by calcination at 500°C in air for 3 h. The sample was then activated by water and chlorine at 450°C for 4 h in air containing HCl and water, and then reduced in hydrogen at 450°C for 4 h to obtain the reduced catalyst b.

[0077] Comparative Example 3

[0078] The specific preparation method includes the following steps: 22.2 mL of chloroplatinic acid aqueous solution with a platinum content of 4.5 mg / mL was mixed with 100 mL of deionized water, and after being uniformly mixed by continuing to stir for 30 min, the γ-Al2O3 carrier prepared above was added to the mixture, and after being uniformly mixed by stirring, the filtrate was evaporated to dryness. The sample was dried at 120°C for 12 h, followed by calcination at 500°C in air for 3 h. The sample was then activated by water and chlorine at 450°C for 4 h in air containing HCl and water, and then reduced in hydrogen at 450°C for 4 h to obtain the reduced catalyst c.

[0079] Test Example 1

[0080] The catalyst evaluation was carried out on a micro-reaction evaluation device, which was a fixed bed reactor with an inner diameter of 10 mm. The upper and lower sections of the reactor were filled with quartz sand, and the middle section was filled with a mixture of 2 mL of catalyst and 6 mL of quartz sand (catalysts A-F, a-c, respectively). The catalysts were evaluated using naphtha as the raw material, wherein the composition of the naphtha is shown in Table 1 (IBP in Table 1 represents the initial boiling point; EBP represents the final boiling point; m(P), m(N) and m(A) represent the mass percentages of alkanes, naphthenes and aromatics, respectively). The evaluation conditions were as follows: a reaction temperature of 500°C, a reaction pressure of 0.35 MPa, a hydrogen / hydrocarbon volume ratio of 800, and a liquid hourly space velocity of 2.0 h -1 The average reaction results after 100 h of cumulative reaction are shown in Table 2. The raw materials and products were analyzed and sampled using an Agilent gas chromatograph equipped with an FID detector. The mass fractions of components such as benzene and toluene in the raw materials and / or products were measured. The bed temperature was also measured to investigate the change in the selectivity of the catalyst with reaction time. The amount of carbon deposited on the catalyst after the reaction was determined using an EMIA-820V infrared sulfur carbon analyzer from HORIBA, Japan, and is listed in Table 2.

[0081] The C 5+ The liquid product yield (Y C5+液体产物收率 ) was calculated according to formula (1):

[0082] Y C5+液体产物收率 = the sum of the mass fractions of C5+ in the products ………… (1)

[0083] The aromatic content (X 芳烃含量 ) in the liquid product was calculated according to formula (2):

[0084] X 芳烃含量 = X 苯 + X 甲苯 + X 混合二甲苯 + X C9+芳烃 ……… (2).

[0085] X 苯 , X 甲苯 , X 混合二甲苯 and X C9+芳烃 represent the mass fraction of benzene, the mass fraction of toluene, the mass fraction of mixed xylene and the mass fraction of C9+ aromatic hydrocarbons in the feed liquid, respectively.

[0086] The aromatic yield (Y 芳烃产率 ) of the catalyst was calculated according to formula (3):

[0087] Y 芳烃产率 = Y C5+液体产物收率 × X 芳烃含量 × 100% ………… (3).

[0088] The octane yield (Q 辛烷值收率 ) of the catalyst is calculated according to formula (4):

[0089] Q 辛烷值收率 = Y C5+液体产物收率 × R 液体产物研究法辛烷值 ……………………………(4).

[0090] The liquid product research octane number (R 液体产物研究法辛烷值 ) is measured by near-infrared method.

[0091] Table 1. Properties of naphtha raw oil

[0092]

[0093] Table 2. Results of catalyst reaction performance evaluation

[0094]

[0095]

[0096] As can be seen from the data of the examples and the comparative examples in Table 2, the naphtha catalytic reforming by the supported catalyst of the application can improve the liquid product yield, increase the aromatic hydrocarbon content in the liquid product, increase the aromatic hydrocarbon yield, increase the octane yield, and reduce the amount of coke.

[0097] As can be seen from the data in Table 2, when the naphtha is catalyzed by the supported catalyst of the examples of the application, when the pH is the same, with the increase of the Sn:Pt atomic ratio, the C5 + The liquid product yield increases, the aromatic hydrocarbon content increases, the aromatic hydrocarbon yield increases, and the octane yield increases. When the pH is different, not only the catalyst performance is obviously different, but also the amount of coke on the catalyst after the reaction is different.

[0098] As can be seen from Comparative Example 1 and Example 1, Comparative Example 1 removes the auxiliary metal in Example 1 and directly impregnates Pt on the alumina carrier. When the platinum loading amount is the same as that of Example 1, the final catalyst has low selectivity for naphtha reforming reaction and the catalyst is easy to coke and deactivate. Comparative Example 1 and Example 1 jointly show that the method described in the application is the key to preparing a Pt-based bimetallic alloy catalyst with high dispersion, high selectivity, and good anti-coking performance.

[0099] Comparative Example 2 removes the ethylene glycol protective agent in Example 1, and directly uses aqueous solution to impregnate under air atmosphere, when the Pt loading amount is the same as Example 1, the final catalyst reforming reaction selectivity is low, and the catalyst is more prone to carbon deposition than Example 1. Comparative Example 2 and Example 1 together show that the bimetallic nanoparticles prepared by the ethylene glycol protection method described in the application can improve the carbon deposition resistance of the catalyst when reloaded on the surface of the alumina carrier.

[0100] From the data in Table 2, it can be seen that the catalyst prepared by the application has a higher yield of reaction liquid products and a lower amount of carbon deposition on the catalyst after the reaction compared with the catalyst prepared by the comparative example.

[0101] Test Example 2

[0102] The catalyst A prepared in Example 1 and the catalyst b prepared in Comparative Example 2 were tested by high-angle annular dark field image scanning transmission electron microscopy, and the obtained HAADF-STEM photos are shown in Figure 1 and Figure 3 The particle size distribution graph of the bimetallic alloy sub-nanometer cluster of Pt and the auxiliary metal in the catalyst A prepared in Example 1 is shown in Figure 2 .

[0103] It can be seen from Figure 1 that the platinum and tin in the supported catalyst prepared by the preparation method of the application are dispersed or anchored on the alumina carrier in the form of bimetallic alloy sub-nanometer clusters. It can be seen from Figure 2 that the particle size distribution range of the bimetallic alloy sub-nanometer clusters of Pt and the auxiliary metal in the supported catalyst prepared in Example 1 is about 0.4-1.7 nm, and the number of particles with a particle size of 0.6-1.2 nm accounts for 80-100%. It can be seen from Figure 3 that the bimetallic active component in the catalyst b prepared in Comparative Example 2 is dispersed on the surface of the carrier in the form of nanoparticles, the particle size distribution is uneven, and the size is large.

[0104] Test Example 3

[0105] The metal components in the catalysts prepared in the examples and the comparative example were determined by fluorescence method, and the chlorine element content was measured by electrode method.

[0106] Table 3

[0107]

[0108]

[0109] In the description of the present application, it needs to be explained that the terms "upper", "lower", "inner", "outer", "front", "back", "left", "right" and the like indicate the orientation or positional relationship based on the working state of the present application, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0110] In the description of the present application, it needs to be explained that the terms "installation", "connection", "connection" should be understood broadly unless otherwise explicitly specified and limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0111] The above describes the present application in combination with the preferred embodiments, but these embodiments are only exemplary and serve only to illustrate. On this basis, various substitutions and improvements can be made to the present application, which all fall within the scope of protection of the present application.

Claims

1. A supported catalyst, characterized in that, It includes an alumina support, Pt, and an auxiliary metal, wherein the auxiliary metal is Ge, Ga, Sn, Zn, or In, and Pt and the auxiliary metal are dispersed on the alumina support in the form of bimetallic alloy sub-nano clusters. In the supported catalyst, Pt forms an alloy with the promoter metal, and the promoter metal is incorporated into the Pt lattice; and The bimetallic alloy sub-nano clusters have a particle size of 0.4~1.7 nm.

2. The supported catalyst according to claim 1, characterized in that, The supported catalyst also includes Cl; Based on the weight of the alumina support, the supported catalyst comprises 0.01~5 wt% Pt, 0.01~10.0 wt% auxiliary metal, and 0.1~5 wt% Cl.

3. The supported catalyst according to claim 2, characterized in that, The atomic ratio of Pt to the auxiliary metal is (0.01~20):1; The bimetallic alloy sub-nano clusters contain 80-100% particles with a diameter of 0.6-1.2 nm.

4. The supported catalyst according to claim 3, characterized in that, The bimetallic alloy sub-nano clusters have a particle size of 1 nm.

5. A method for preparing the supported catalyst according to any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Add the Pt precursor to a reducing organic solvent to obtain the first solution; (2) Add the auxiliary metal precursor to a reducing organic solvent to obtain a second solution; (3) The first solution obtained from step (1) and the second solution obtained from step (2) are simultaneously added to a reducing organic solvent, while adjusting the pH value of the solution to maintain alkalinity, and then heated to 120~180℃ to obtain a mixed solution; (4) The alumina support is added to the mixture obtained from step (3) for impregnation, drying and calcination to obtain an intermediate product; (5) The intermediate product obtained from step (4) is activated and reduced with water and chlorine; In step (3), the rate at which the first solution and the second solution are added to the reducing organic solvent is such that the atomic ratio of Pt added to the reducing organic solvent to the auxiliary metal is maintained at (0.01~20):

1.

6. The method according to claim 5, characterized in that, In step (1): The step of adding the Pt precursor to the reducing organic solvent includes: adding the Pt precursor to the first part of the reducing organic solvent, and then mixing it with the second part of the reducing organic solvent; The Pt precursor is one or more of the following: chloroplatinic acid, ammonium chloroplatinate, bromoplatinic acid, platinum trichloride, platinum tetrachloride hydrate, dichlorocarbonyl platinum dichloride, dinitrodiaminoplatinum, tetranitroplatinic acid, and platinum acetylacetonate. The reducing organic solvent is one or more of methanol, ethylene glycol and formaldehyde; The concentration of Pt in the first solution is 0.5~5 mg / mL.

7. The method according to claim 6, characterized in that, In step (2): The auxiliary metal precursor is one of germanium nitrate, boron nitrate, zinc nitrate, tin tetrachloride, stannous chloride, and indium nitrate; The concentration of the auxiliary metal in the second solution is 0.5~5 mg / mL; The reducing organic solvent is one or more of methanol, ethylene glycol, and formaldehyde.

8. The method according to claim 7, characterized in that, In step (3): The reducing organic solvent is one or more of methanol, ethylene glycol, and formaldehyde.

9. The method according to claim 7, characterized in that, In step (3): In the mixture, the concentrations of Pt and the auxiliary metal are each independently 0.1~2.5 mg / mL.

10. The method according to claim 5, characterized in that, In step (3): Adjusting the pH of a solution to maintain alkalinity involves adding an alkaline solution to adjust the pH to 8-14.

11. The method according to claim 10, characterized in that, In step (3): The alkaline solution is selected from ammonia water, urea solution, sodium hydroxide solution or potassium hydroxide solution.

12. The method according to claim 11, characterized in that, The alkaline solution is ammonia.

13. The method according to claim 12, characterized in that, The concentration of the ammonia water is 5 to 30 wt%.

14. The method according to claim 11, characterized in that, In step (4): The alumina support has a pore volume of 0.3–1.2 g / mL and a specific surface area of ​​50–300 m². 2 / g; The drying temperature is 50~300 ℃, and the time is 2~48 h.

15. The method according to claim 14, characterized in that, In step (5): The water chlorination activation includes heating the intermediate product obtained from step (4) in air containing HCl and H2O; The molar ratio of H2O to HCl in the air containing HCl and H2O is (10~100):1; The heating temperature is 370~700℃, and the time is 1~16 h; and / or The reduction is carried out at a temperature of 250~650 °C for a time of 0.5~16 h in a reducing atmosphere containing hydrogen or carbon monoxide, with a volume fraction of 10~100%.

16. A method for naphtha catalytic reforming, characterized in that, include: Under catalytic reforming conditions, naphtha is contacted with a supported catalyst to react, wherein the supported catalyst is the supported catalyst according to any one of claims 1-4 or is prepared by the method according to any one of claims 5-15.

17. The method according to claim 16, characterized in that, The catalytic reforming reaction conditions include: Temperature: 360~600℃; Pressure: 0.1~1.0 MPa; Liquid feed volumetric hourly space velocity: 1~20 h⁻¹ -1 The hydrogen / hydrocarbon volume ratio is 500~2000.

18. The method according to claim 17, characterized in that, The naphtha is selected from at least one of straight-run naphtha, hydrocracked naphtha, coking naphtha, catalytic cracked naphtha, and ethylene cracked naphtha.

19. The method according to claim 18, characterized in that, The naphtha contains alkanes, cycloalkanes, and aromatics.

20. The method according to claim 19, characterized in that, The naphtha contains hydrocarbons with 5 to 12 carbon atoms.

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