CN117358232A

CN117358232A - Supported catalyst, preparation method and catalytic reforming method

Info

Publication number: CN117358232A
Application number: CN202210769835.8A
Authority: CN
Inventors: 李筱玉; 刘建良; 马爱增; 王杰广; 王春明; 刘彤
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2022-06-30
Filing date: 2022-06-30
Publication date: 2024-01-09

Abstract

The invention discloses a supported catalyst, a preparation method and a catalytic reforming method, wherein the supported catalyst comprises an Sn-containing alumina carrier and an active component, the active component comprises Pt, and the Pt is dispersed on the Sn-containing alumina carrier in a sub-nanocluster mode. The method for preparing the supported catalyst comprises the following steps: (1) Adding a Pt precursor into a reducing organic solvent to obtain a first solution; (2) Adjusting the pH value of the first solution to 8-14 to obtain a second solution; (3) Adding the Sn-containing alumina carrier into the second solution for impregnation, drying and roasting to obtain an intermediate product; (4) The intermediate product from step (3) is subjected to aqueous chlorine activation and reduction. In the supported catalyst for catalyzing the reforming reaction, pt is dispersed on the Sn-containing alumina carrier in the form of sub-nanoclusters, and the catalyst has better catalytic selectivity and carbon deposit resistance for catalyzing the reforming reaction of naphtha and can obviously improve the yield of liquid products.

Description

Supported catalyst, preparation method and catalytic reforming method

Technical Field

The invention relates to the technical field of catalytic reforming, in particular to a supported catalyst, a preparation method and a catalytic reforming method.

Background

Catalytic reforming processes hydrocarbon molecules in naphtha into aromatics, hydrogen and high octane gasoline components, which is one of the main technologies in the modern petrochemical industry. Catalytic reforming processes are widely used to upgrade heavy gasoline grade where hydrocarbons containing 6 to 12 carbon atoms per molecule in heavy gasoline (paraffins and naphthenes) produce aromatics or branched paraffins. The reforming reaction is carried out at high temperature (500 ℃), low to medium pressure (3.5X10) ⁵ ～25×10 ⁵ Pa) in the presence of a catalyst. The catalytic reforming generated oil can be used for improving the octane number of oil components, and the reforming generated oil mainly comprises C ₅ ⁺ Hydrocarbon composition (containing at least 5 carbon atoms). The process also generates H ₂ Fuel gas (from C ₁ -C ₂ Hydrocarbon formation) and liquefied gas (from C ₃ -C ₄ Hydrocarbon formation). In addition, coke deposited on the active sites of the catalyst is also formed by aromatic ring condensation.

In the catalytic reforming process, competing reactions simultaneously occur, including cyclohexane dehydrogenation to aromatics, alkyl cyclohexane dehydrogenation isomerization to aromatics, and naphthene dehydrogenation cyclization to aromatics. In these reactions, the gasoline yield is reduced due to the light hydrocarbon gas produced by hydrocracking, the catalyst deactivation rate is accelerated by coking reactions, and frequent catalyst regeneration increases the operating costs of the apparatus. It has been a goal to develop a high selectivity, low carbon deposition rate catalytic reforming catalyst and process.

In commercial reforming catalysts, the platinum content is typically a few thousandths, with platinum in Al to provide sufficient metal center ₂ O ₃ The dispersion state is critical for determining the catalyst performance. To improve Pt/Al ₂ O ₃ The performance of the catalyst is often modified by adopting other metals as auxiliary agents to modify the metal center and the acid center of the catalyst, so that the activity stability and the selectivity of the catalyst are further improved, the service life of the catalyst is further prolonged, and the influence of the auxiliary agents on the dispersion state, microstructure, metal function, acid function of the carrier, action mechanism and the like of platinum are key scientific problems of research.

How to design a catalyst for catalytic reforming reaction, so that platinum is dispersed on a carrier in a better form, to improve the catalytic selectivity and the carbon deposit resistance, and avoid frequent regeneration or final deactivation of the catalyst caused by carbon deposit in the use process, which is a technical problem to be solved at present.

Disclosure of Invention

The invention provides a supported catalyst, a preparation method and a catalytic reforming method, which are used for improving the selectivity and the carbon deposit resistance of a catalytic reforming reaction catalyst.

In a first aspect, the present invention provides a supported catalyst comprising a Sn-containing alumina support and an active component comprising Pt dispersed as sub-nanoclusters on the Sn-containing alumina support.

Optionally, the active component further comprises Cl; based on the weight of the Sn-containing alumina carrier, the content of Pt is 0.01 to 5 weight percent, the content of Sn is 0.1 to 10.0 weight percent, and the content of Cl is 0.1 to 5 weight percent; the atomic ratio of Pt to Sn is (0.01-20): 1.

optionally, the particle size of the sub-nanoclusters is 0.5-2.0nm; in the sub-nanocluster, the number of particles with the particle size of 0.7-1.3nm accounts for 80% -100%; preferably, the particle size of the sub-nanoclusters is 1nm.

In a second aspect, the present invention provides a method for preparing the above supported catalyst, comprising the steps of: (1) Adding a Pt precursor into a reducing organic solvent to obtain a first solution; (2) Adjusting the pH of the first solution from step (1) to 8-14, and then heating to obtain a second solution; (3) Adding an Sn-containing alumina carrier to the second solution from step (2) for impregnation, drying and calcination to obtain an intermediate product; (4) Subjecting the intermediate product from step (3) to aqueous chlorine activation and reduction.

Optionally, in step (1): the adding of the Pt precursor to the reducing organic solvent includes: adding a Pt precursor to a first portion of the reducing organic solvent and then mixing with a second portion of the reducing organic solvent; the Pt precursor comprises at least one of chloroplatinic acid, ammonium chloroplatinate, bromoplatinic acid, platinum trichloride, platinum tetrachloride hydrate, dichloroplatinum carbonyl dichloride, dinitrodiamido platinum, tetranitro platinic acid and platinum acetylacetonate; the reducing organic solvent is one or more of ethylene glycol, methanol and formaldehyde; the concentration of Pt in the first solution is 0.25-5 mg/mL.

Optionally, in step (2): adjusting the pH by adding an alkaline solution to the first solution; the alkali solution is selected from one or more of ammonia water, urea solution, potassium hydroxide solution or sodium hydroxide solution; preferably, the alkaline solution is selected from ammonia; preferably, the concentration of the aqueous ammonia solution is 5 to 35wt%.

Optionally, in step (3): the pore volume of the Sn-containing alumina carrier is 0.3-1.2 g/mL, and the specific surface area is 50-300 m ² /g; the drying temperature is 50-300 ℃ and the drying time is 2-48h.

Optionally, in step (4): the aqueous chlorine activation comprises subjecting the intermediate product from step (3) to a reaction system comprising HCl and H ₂ Heating in O air; the said catalyst contains HCl and H ₂ H in air of O ₂ The mol ratio of O to HCl is (10-100) 1, the heating temperature is 370-700 ℃ and the heating time is 1-16 h; and/or the reduction is carried out in a reducing atmosphere containing hydrogen or carbon monoxide with a volume fraction of 10 to 10100%; the temperature of the reduction is 250-700 ℃ and the time is 0.5-16 h.

In a third aspect, the present invention provides a method for catalytic reforming of naphtha, comprising contacting naphtha with a supported catalyst under catalytic reforming reaction conditions of naphtha, wherein the supported catalyst is the supported catalyst described above or the supported catalyst prepared by the method described above.

Optionally, the naphtha catalytic reforming reaction conditions include: the temperature is 360-600 ℃, the pressure is 0.1-1.0 MPa, and the space velocity of the liquid feeding volume is 1-20 h ^-1 The hydrogen/hydrocarbon volume ratio is 500-2000.

Optionally, the naphtha is selected from at least one of straight run naphtha, hydrocracked naphtha, coker naphtha, catalytically cracked naphtha, and ethylene cracked naphtha; preferably, the naphtha contains paraffins, naphthenes and aromatics; preferably, the naphtha contains hydrocarbons having a carbon number of 5 to 12.

The beneficial effects are that:

in the supported catalyst for catalyzing the reforming reaction, pt is dispersed on the Sn-containing alumina carrier in the form of sub-nanoclusters, and the catalyst has better catalytic selectivity and carbon deposit resistance for catalyzing the reforming reaction of naphtha and can obviously improve the yield of liquid products.

Drawings

FIG. 1 is a supported catalyst Pt/Al prepared in example 1 ₂ O ₃ HAADF-STEM photograph of Sn.

FIG. 2 is a supported catalyst Pt/Al prepared in example 1 ₂ O ₃ Particle size distribution of Pt sub-nanoclusters in Sn.

FIG. 3 is a supported catalyst Pt/Al prepared in comparative example 1 ₂ O ₃ HAADF-STEM photograph of Sn.

Detailed Description

The present application is further described in detail below by way of the accompanying drawings and examples. The features and advantages of the present application will become more apparent from the description.

The word "exemplary" is used herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are illustrated in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

In addition, the technical features described below in the different embodiments of the present application may be combined with each other as long as they do not collide with each other.

It should be noted that the supported catalyst of the present invention may be used in catalytic reforming reactions of naphtha. In the supported catalyst, pt is dispersed in the Sn-containing alumina carrier in the form of sub-nanoclusters, so that the Pt has better dispersibility; in addition, by improving the dispersibility of the active component Pt on the Sn-containing alumina carrier, the activity, stability and selectivity of the catalyst can be effectively improved, the generation of carbon deposit in the use process of the catalyst can be effectively reduced, and the service life of the catalyst can be further prolonged.

According to one embodiment, the active component further comprises Cl; based on the weight of the Sn-containing alumina carrier, the content of Pt is 0.01 to 5 weight percent, the content of Sn is 0.1 to 10.0 weight percent, and the content of Cl is 0.1 to 5 weight percent; the atomic ratio of Pt to Sn is (0.01-20): 1. preferably, the content of Pt is 0.02 to 1wt%, and the atomic ratio of Pt to Sn is (0.5 to 10): 1.

in the supported catalyst of the present invention, pt can exhibit a hydrogenation/dehydrogenation function as a metal center, cl can exhibit an isomerization/acidity function as an acid center, and Sn can modify the metal center and the acid center of the catalyst to improve the catalyst performance.

According to one embodiment, the sub-nanoclusters have a particle size of 0.5 to 2.0nm; in the sub-nanocluster, the number of particles with the particle size of 0.7-1.3nm accounts for 80% -100%; preferably, the particle size of the sub-nanoclusters is 1nm.

In a preferred embodiment, the supported catalyst of the present invention comprises a carrier surface of an alumina containing Sn, wherein Pt as an active ingredient is dispersed in the form of sub-nanoclusters, and the content of Pt, the content of Sn, the content of Cl and the atomic ratio of Pt to Sn are controlled comprehensively, and in particular, the number of sub-nanocluster particles having a particle diameter of 0.7 to 1.3nm is 80% to 100%, so that the supported catalyst can achieve better catalytic selectivity and less carbon deposition.

In the method for preparing the supported catalyst, the first solution is a reducing organic solution of a Pt precursor, the pH value is adjusted and the solution is heated in the step (2), pt in the obtained second solution exists in the form of sub-nanoclusters, and then the Pt is supported on the surface of the Sn-containing alumina carrier in the form of the sub-nanoclusters through the dipping and post-treatment processes in the step (3).

Based on one embodiment, in step (1): the adding of the Pt precursor to the reducing organic solvent includes: the Pt precursor is added to a first portion of the reducing organic solvent and then mixed with a second portion of the reducing organic solvent. The Pt precursor includes at least one of chloroplatinic acid, ammonium chloroplatinate, bromoplatinic acid, platinum trichloride, platinum tetrachloride hydrate, platinum dichloride carbonyl dichloride, dinitrodiamido platinum, tetranitro platinic acid, and platinum acetylacetonate. In the preparation process, the concentration of Pt in the first solution is controlled to be 0.25-5 mg/mL. The concentration of Pt may refer to the concentration by mass of Pt. In one embodiment, the reducing organic solvent is one or more of ethylene glycol, methanol, and formaldehyde. In the application, the reducing organic solvent mainly plays a role in reducing metal ions in the solution into metal atoms, and the metal atoms are aggregated and nucleated to finally generate sub-nanoclusters.

In the preparation process of the application, the step (1) is performed in an inert atmosphere, wherein the inert atmosphere is one or more than two of argon, nitrogen and helium.

In the step (1), a certain amount of platinum metal precursor is added into a reducing organic solvent such as ethylene glycol, and stirred for 5-15 minutes to be uniformly mixed, so as to obtain the first solution. Or taking a certain amount of the reducing organic solution of the platinum metal precursor, adding the reducing organic solution into a certain volume of the reducing organic solvent, and uniformly mixing to obtain the first solution. During the preparation of the first solution, a reducing organic solvent such as ethylene glycol is selected as a solvent, and then the Pt in the second solution exists in the form of sub-nanoclusters after the combination of the processing procedure of the step (2), and then the Pt can be loaded on the surface of the Sn-containing alumina carrier in the form of sub-nanoclusters through the impregnation and post-treatment procedures of the step (3).

In a preferred embodiment, the reducing organic solvent is ethylene glycol.

Based on another embodiment, in step (2): the adjustment of the pH is performed by adding an alkaline solution, such as one or more of ammonia, urea solution, potassium hydroxide solution or sodium hydroxide solution, to the first solution. Preferably, the alkaline solution is aqueous ammonia, in which case no elements are introduced into the catalyst that might be detrimental to the catalyst activity. Preferably, the concentration of the aqueous ammonia solution is 5 to 35wt%, such as may be 10wt%. In one embodiment, after adjusting the pH, heating is also performed, comprising: heating the solution with the pH value regulated to 120-180 ℃, stirring for 2-8h, and cooling to room temperature. In one embodiment, the cooling is performed in an inert atmosphere, wherein the inert atmosphere is one or more of argon, nitrogen and helium.

When the pH value is adjusted to a target value by adding ammonia or the like to the first solution, the solution after the pH value adjustment may be heated by means of an oil bath, a water bath, a sand bath or the like while stirring.

In a preferred embodiment, the pH is adjusted by adding aqueous ammonia to the first solution.

Based on one embodiment, in step (3): the pore volume of the Sn-containing alumina carrier is 0.3-1.2 g/mL, and the specific surface area is 50-300 m ² And/g. The impregnation can be carried out in a closed container, the impregnation temperature is 10-80 ℃, and the impregnation time is 10-100 h. After impregnation, drying treatment is also carried out, wherein the drying temperature is 50-300 ℃ and the time is 2-48h.

And then, performing water chlorine activation treatment on the catalyst intermediate product. Based on one embodiment, in step (4): the aqueous chlorine activation comprises subjecting the intermediate product from step (3) to a reaction system comprising HCl and H ₂ And (3) performing heating treatment in the air of O. The said catalyst contains HCl and H ₂ H in air of O ₂ The molar ratio of O to HCl is (10-100): 1. The heating temperature is 370-700 ℃ and the heating time is 1-16 h.

After the water chlorine activation treatment, a reduction treatment is also performed. The reduction is carried out in a reducing atmosphere containing hydrogen or carbon monoxide. The volume fraction of the hydrogen or the carbon monoxide is 10-100%. The temperature of the reduction is 250-700 ℃ and the time is 0.5-16 h.

By placing the intermediate product in a solution containing HCl and H ₂ The chlorine content and the acid site density in the catalyst can be improved by water chlorine activation in O air, so that the prepared supported catalyst has better catalytic selectivity.

In a third aspect, the present invention provides a method for catalytic reforming of naphtha, wherein naphtha is contacted with a supported catalyst under catalytic reforming reaction conditions of naphtha, and the supported catalyst is the supported catalyst or the supported catalyst prepared by the method.

As described above, in the supported catalyst of the present invention, pt is dispersed on the surface of the Sn-containing alumina carrier in the form of sub-nanoclusters, so that Pt has better dispersibility, and therefore, better catalytic selectivity can be obtained when the naphtha catalytic reforming reaction is performed in the presence of the supported catalyst, the aromatic hydrocarbon content in the liquid product is increased, and the carbon deposition rate is reduced.

According to one embodiment, the naphtha catalytic reforming reaction conditions include:

the temperature is 360-600 ℃, the pressure is 0.1-1.0 MPa, and the space velocity of the liquid feeding volume is 1-20 h ^-1 The hydrogen/hydrocarbon volume ratio is 500-2000.

The hydrogen/hydrocarbon volume ratio may be 200 to 2000. Based on the catalytic action of the supported catalyst, the naphtha catalytic reforming reaction can further obtain better catalytic selectivity, improve the aromatic hydrocarbon content in the liquid product and reduce the carbon deposition rate under the conditions.

According to one embodiment, the naphtha is selected from at least one of straight run naphtha, hydrocracked naphtha, coker naphtha, catalytically cracked naphtha, and ethylene cracked naphtha; preferably, the naphtha contains paraffins, naphthenes and aromatics, and the naphtha contains hydrocarbons with a carbon number of 5-12.

The naphtha may have a primary boiling point of 40 to 100 ℃, preferably 70 to 90 ℃, and a final boiling point of 140 to 220 ℃, preferably 160 to 180 ℃ as determined by astm d-86. The process for the catalytic reforming of naphtha according to the invention is preferably carried out in a sulfur-free or low sulfur environment and the sulfur content of the naphtha may be not higher than 1.0. Mu.g/g, preferably not higher than 0.5. Mu.g/g. In order to achieve the desired sulfur content, the naphtha may be desulfurized prior to catalytic reforming by a variety of desulfurization methods, including adsorption desulfurization, catalytic desulfurization, which are well known to those skilled in the art and are not described in detail herein.

The invention is illustrated in further detail by the following examples.

Carrier preparation example

137.4g of pseudo-boehmite powder (trade name SB, manufactured by Condea Corp., germany, alumina content 72.8% by weight)0.60g of SnCl ₂ ·2H ₂ Mixing O and 350g of deionized water, stirring for 0.5h, dropwise adding 14g of 22wt% nitric acid solution, stirring for 2h at 20 ℃, adding 30g of kerosene and 3g of fatty alcohol polyoxyethylene ether, and dropwise adding into an oil ammonia column to form the oil ammonia column. Solidifying the wet ball in ammonia water for 1h, filtering, washing with deionized water, drying at 60deg.C for 6h, drying at 120deg.C for 10h, and calcining at 600deg.C for 4h to obtain Sn-containing gamma-Al ₂ O ₃ A carrier of N ₂ Specific surface area of adsorption (BET) test support was 210m ² Per gram, pore volume was 0.6mL/g.

Example 1

Under the protection of Ar atmosphere, 22.2mL of ethylene glycol chloroplatinate solution with the platinum content of 4.5mg/mL is mixed with 200mL of ethylene glycol, an ammonia water solution with the concentration of 25wt% is added to adjust the pH value of the solution to be 12, stirring is continued for 30 minutes and mixing is uniform, the mixed solution is transferred into an oil bath pot and stirred for 3 hours at 150 ℃, the inert atmosphere is protected and cooled to room temperature, and then the prepared Sn-containing gamma-Al is prepared ₂ O ₃ Adding the carrier into the mixed solution, stirring for 3 hours until the mixture is uniform, washing and filtering the catalyst at room temperature, transferring the filtered product to a 120 ℃ oven for drying for 12 hours, roasting for 3 hours in an air atmosphere at 500 ℃, and introducing air containing HCl and water into the roasted sample at 450 ℃ for water chlorine activation for 4 hours. Then reducing for 4h in hydrogen at 450 ℃ to obtain the reduced catalyst A.

Example 2

Under the protection of Ar atmosphere, 22.2mL of ethylene glycol chloroplatinate solution with the platinum content of 4.5mg/mL is mixed with 200mL of ethylene glycol, an ammonia water solution with the concentration of 25wt% is added to adjust the pH value of the solution to 8, stirring is continued for 30 minutes and mixing is uniform, the mixed solution is transferred into an oil bath pot and stirred for 3 hours at 150 ℃, the inert atmosphere is protected and cooled to room temperature, and then the prepared Sn-containing gamma-Al is prepared ₂ O ₃ Adding the carrier into the mixed solution, stirring for 3 hours until the carrier is uniformly mixed, washing and filtering the catalyst at room temperature, transferring the filtered product to a 120 ℃ oven for drying for 12 hours, roasting for 3 hours in an air atmosphere at 500 ℃, and introducing air containing HCl and water into the roasted sample at 450 ℃ for water chlorine activation for 4 hoursh. Then reducing for 4h in hydrogen at 450 ℃ to obtain the reduced catalyst B.

Example 3

Under the protection of Ar atmosphere, 22.2mL of ethylene glycol chloroplatinate solution with the platinum content of 4.5mg/mL is mixed with 200mL of ethylene glycol, an ammonia water solution with the concentration of 25wt% is added to adjust the pH value of the solution to be 14, stirring is continued for 30 minutes and mixing is uniform, the mixed solution is transferred into an oil bath pot and stirred for 3 hours at 150 ℃, the inert atmosphere is protected and cooled to room temperature, and then the prepared Sn-containing gamma-Al is prepared ₂ O ₃ Adding the carrier into the mixed solution, stirring for 3 hours until the mixture is uniform, washing and filtering the catalyst at room temperature, transferring the filtered product to a 120 ℃ oven for drying for 12 hours, roasting for 3 hours in an air atmosphere at 500 ℃, and introducing air containing HCl and water into the roasted sample at 450 ℃ for water chlorine activation for 4 hours. Then reducing for 4h in hydrogen at 450 ℃ to obtain the reduced catalyst C.

Example 4

Under the protection of Ar atmosphere, mixing 33.3mL of ethylene glycol chloroplatinate solution with the platinum content of 4.5mg/mL with 200mL of ethylene glycol, adding an ammonia water solution with the concentration of 25wt% to adjust the pH value of the solution to be 12, continuously stirring for 30 minutes, uniformly mixing, transferring the mixed solution into an oil bath pot, stirring for 3 hours at 150 ℃, reducing the temperature to room temperature under the protection of inert atmosphere, and then preparing the Sn-containing gamma-Al ₂ O ₃ Adding the carrier into the mixed solution, stirring for 3 hours until the mixture is uniform, washing and filtering the catalyst at room temperature, transferring the filtered product to a 120 ℃ oven for drying for 12 hours, roasting for 3 hours in an air atmosphere at 500 ℃, and introducing air containing HCl and water into the roasted sample at 450 ℃ for water chlorine activation for 4 hours. Then reducing for 4h in hydrogen at 450 ℃ to obtain the reduced catalyst D.

Comparative example 1

The preparation method comprises the following steps: adding 22.2mL of chloroplatinic acid aqueous solution with platinum content of 4.5mg/mL into 200mL of deionized water, continuously stirring for 30 minutes, uniformly mixing, and then adding the prepared Sn-containing gamma-Al ₂ O ₃ Adding the carrier into the mixed solution, stirring for 3 hr until the mixture is uniform, and steaming the filtrateDrying at 120 ℃ for 12 hours, roasting at 500 ℃ for 3 hours in an air atmosphere, and introducing air containing HCl and water into the roasted sample at 450 ℃ for water chlorine activation for 4 hours. Then reducing for 4h in hydrogen at 450 ℃ to obtain the reduced catalyst a.

Test example 1

Catalyst evaluation was performed on a micro-reaction evaluation device, which is a fixed bed reactor, the inner diameter of the reactor is 10mm, the upper and lower sections of the reactor are filled with quartz sand, 2mL of catalyst and 6mL of quartz sand mixture (the catalyst is A-D and a respectively) are filled in the middle part, and the catalyst is evaluated by taking naphtha as raw material, wherein the composition of the naphtha is shown in table 1 (IBP represents initial distillation point; EBP represents final distillation point, and m (P), m (N) and m (A) represent alkane mass percent, cycloalkane mass percent and arene mass percent respectively). The evaluation conditions were: the reaction temperature is 500 ℃, the reaction pressure is 0.35MPa, the hydrogen/hydrocarbon volume ratio is 800, and the feed liquid hourly space velocity is 2.0h ^-1 . The average reaction results of the cumulative reaction for 100 hours are shown in Table 2. The raw materials and the products are subjected to Agilent gas chromatography and are provided with an FID detector for analysis and sampling, and the mass fractions of benzene, toluene and other components in the raw materials and/or the products are measured. The bed temperature was also measured to examine the change in selectivity of the catalyst with the reaction time, and the amount of carbon deposit of the catalyst after the reaction was measured by using an EMIA-820V type infrared sulfur carbon meter of HORIBA corporation of japan and is shown in table 2.

Catalyst C ₅₊ Liquid product yield (Y) _{C5+ liquid product yield} ) Calculated according to formula (1):

Y _{c5+ liquid product yield} Sum … … … … … of mass fractions of c5+ in the product (1).

Aromatic hydrocarbon content in liquid product (X _{Aromatic hydrocarbon content} ) Calculated according to formula (2):

X _{aromatic hydrocarbon content} ＝X _Benzene +X _{Toluene (toluene)} +X _{Mixing xylenes} +X _{C9+ aromatic hydrocarbons} ……………………(2)。

X _Benzene 、X _{Toluene (toluene)} 、X _{Mixing xylenes} And X _{C9+ aromatic hydrocarbons} Respectively refers to the mass fraction of benzene and the mass of toluene in the discharged liquidFraction, mass fraction of mixed xylenes and mass fraction of c9+ aromatics.

Aromatic hydrocarbon yield of catalyst (Y _{Aromatic hydrocarbon yield} ) Calculated according to formula (3):

Y _{aromatic hydrocarbon yield} ＝Y _{C5+ liquid product yield} ×X _{Aromatic hydrocarbon content} ×100％……………………(3)。

Octane number yield of catalyst (Q) _{Octane number yield} ) Calculated according to formula (4):

Q _{octane number yield} ＝Y _{C5+ liquid product yield} ×R _{Liquid product research octane number} ………………………(4)。

Liquid product research octane number (R _{Liquid product research octane number} ) Measured by a near infrared method.

TABLE 1 Properties of naphtha feedstock

TABLE 2 evaluation of catalyst reactivity results

As can be seen from the data of examples 1 to 4 and comparative example 1 in table 2, the catalytic reforming of naphtha by the supported catalyst of the present invention can increase the yield of liquid products, increase the content of aromatic hydrocarbons in liquid products, increase the yield of aromatic hydrocarbons, increase the yield of octane number, and reduce the amount of carbon deposit.

Comparative example 1 the ethylene glycol of example 1 was removed and Pt was directly impregnated on the alumina support, and when the platinum loading was the same as in example 1, the final catalyst had low selectivity for the naphtha reforming reaction and the catalyst was susceptible to deactivation of carbon deposit. Comparative example 1 is described in conjunction with example 1: the method is the key for preparing the Pt sub-nanocluster catalyst with high dispersion, high selectivity and excellent carbon deposit resistance.

As can be seen from the data in Table 1, the catalyst of the present invention has a higher yield of the reaction liquid product than the catalyst prepared in the comparative example, and the amount of carbon deposit on the catalyst after the reaction is low. In conclusion, the catalyst provided by the invention has good selectivity and carbon deposit resistance when being applied to naphtha catalytic reforming, and can obviously improve the yield of liquid products. Meanwhile, in the use process, the catalyst has a stable structure and is not easy to agglomerate.

Test example 2

Catalyst a prepared in example 1 and catalyst a prepared in comparative example 1 were examined by high angle annular dark field image scanning transmission electron microscopy, HAADF-STEM photographs were shown in fig. 1 and 3, respectively, and particle size distribution diagrams of Pt sub-nanoclusters in the catalyst of example 1 were shown in fig. 2.

As can be seen from fig. 1, in the catalyst prepared by the preparation method of the present application, platinum is dispersed or anchored on a tin-containing alumina support in the form of sub-nanoclusters. As can be seen from FIG. 2, in the catalyst prepared in example 1, the Pt sub-nanocluster has a particle size distribution ranging from about 0.5 to 2.0nm, mainly from 0.7 to 1.3nm; the number of the particles with the particle diameter of 0.7-1.3nm accounts for 80-100 percent.

As can be seen from fig. 3, the catalyst of comparative example 1 had a very irregular Pt particle size distribution, and the same Pt content gave a smaller visible particle size in the field of view and many noise points.

Test example 3

The contents of the metal elements in the catalysts of the above examples and comparative examples were measured by an X-ray fluorescence method, and the contents of chlorine elements were measured by an electrode method, and the measurement results are shown in Table 3.

TABLE 3 Table 3

In the description of the present application, it should be noted that the directions or positional relationships indicated by the terms "upper", "lower", "inner", "outer", "front", "rear", "left", "right", etc. are based on the directions or positional relationships in the working state of the present application, are merely for convenience of description and simplification of description, and do not indicate or imply that the apparatus or element to be referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present application.

In the description of the present application, it should be noted that the terms "mounted," "connected," and "connected" are to be construed broadly, unless explicitly specified and limited otherwise. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art in a specific context.

The present application has been described in connection with the preferred embodiments, but these embodiments are merely exemplary and serve only as illustrations. On the basis of this, many alternatives and improvements can be made to the present application, which fall within the scope of protection of the present application.

Claims

1. A supported catalyst comprising a Sn-containing alumina support and an active component comprising Pt dispersed as sub-nanoclusters on the Sn-containing alumina support.

2. The supported catalyst of claim 1, wherein the active component further comprises Cl;

based on the weight of the Sn-containing alumina carrier, the content of Pt is 0.01 to 5 weight percent, the content of Sn is 0.1 to 10.0 weight percent, and the content of Cl is 0.1 to 5 weight percent;

the atomic ratio of Pt to Sn is (0.01-20): 1.

3. the supported catalyst of claim 2, wherein the sub-nanoclusters have a particle size of 0.5 to 2.0nm;

in the sub-nanocluster, the number of particles with the particle size of 0.7-1.3nm accounts for 80% -100%;

preferably, the particle size of the sub-nanoclusters is 1nm.

4. A process for preparing a supported catalyst according to any one of claims 1 to 3, characterized in that it comprises the steps of:

(1) Adding a Pt precursor into a reducing organic solvent to obtain a first solution;

(2) Adjusting the pH of the first solution from step (1) to 8-14, and then heating to obtain a second solution;

(3) Adding an Sn-containing alumina carrier to the second solution from step (2) for impregnation, drying and calcination to obtain an intermediate product;

(4) Subjecting the intermediate product from step (3) to aqueous chlorine activation and reduction.

5. The method of claim 4, wherein in step (1):

the adding of the Pt precursor to the reducing organic solvent includes: adding a Pt precursor to a first portion of the reducing organic solvent and then mixing with a second portion of the reducing organic solvent;

the Pt precursor comprises at least one of chloroplatinic acid, ammonium chloroplatinate, bromoplatinic acid, platinum trichloride, platinum tetrachloride hydrate, dichloroplatinum carbonyl dichloride, dinitrodiamido platinum, tetranitro platinic acid and platinum acetylacetonate;

the reducing organic solvent is one or more of ethylene glycol, methanol and formaldehyde;

the concentration of Pt in the first solution is 0.25-5 mg/mL.

6. The method of claim 5, wherein in step (2):

adjusting the pH by adding an alkaline solution to the first solution;

the alkali solution is selected from one or more of ammonia water, urea solution, potassium hydroxide solution or sodium hydroxide solution; preferably, the alkaline solution is selected from ammonia; preferably, the concentration of the aqueous ammonia solution is 5 to 35wt%.

7. The method of claim 6, wherein in step (3):

the pore volume of the Sn-containing alumina carrier is 0.3-1.2 g/mL, and the specific surface area is 50-300 m ² /g；

The drying temperature is 50-300 ℃ and the drying time is 2-48h.

8. The method of claim 7, wherein in step (4):

the aqueous chlorine activation comprises subjecting the intermediate product from step (3) to a reaction system comprising HCl and H ₂ Heating in O air;

the said catalyst contains HCl and H ₂ H in air of O ₂ The mol ratio of O to HCl is (10-100) 1, the heating temperature is 370-700 ℃ and the heating time is 1-16 h; and/or

The reduction is carried out in a reducing atmosphere containing hydrogen or carbon monoxide, and the volume fraction of the hydrogen or the carbon monoxide is 10-100 percent;

the temperature of the reduction is 250-700 ℃ and the time is 0.5-16 h.

9. A method for catalytic reforming of naphtha, characterized in that naphtha is contacted with a supported catalyst under catalytic reforming reaction conditions of naphtha, said supported catalyst being a supported catalyst according to any one of claims 1 to 3 or being prepared by a method according to any one of claims 4 to 8.

10. The method of claim 9, wherein the naphtha catalytic reforming reaction conditions comprise:

11. The method of claim 10, wherein the naphtha is selected from at least one of straight run naphtha, hydrocracked naphtha, coker naphtha, catalytically cracked naphtha, and ethylene cracked naphtha;

preferably, the naphtha contains paraffins, naphthenes and aromatics;

preferably, the naphtha contains hydrocarbons having a carbon number of 5 to 12.