Supported catalyst, method of preparation and catalytic reforming process
By preparing Pt sub-nano cluster catalysts on Sn alumina supports and combining Cl as acid centers, the problem of catalyst deactivation due to coking was solved, achieving high selectivity and anti-coking effects, and improving the efficiency of catalytic reforming reactions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2022-06-30
- Publication Date
- 2026-06-16
AI Technical Summary
Existing catalytic reforming catalysts are prone to deactivation due to carbon buildup during use, leading to frequent regeneration and increased operating costs. Improving catalytic selectivity and resistance to carbon buildup is an urgent problem to be solved.
A highly dispersed catalyst was prepared by using a supported catalyst with Pt dispersed in sub-nano clusters on a Sn-containing alumina support and by adjusting the pH value, activating with water chlorine and reducing the catalyst. The catalyst activity and stability were improved by combining Cl as an acid center.
It significantly improved the catalytic selectivity and anti-coking ability of catalytic reforming reaction, extended catalyst life, increased liquid product yield and aromatic content, and reduced coking rate.
Smart Images
Figure CN117358232B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of catalytic reforming technology, specifically to a supported catalyst, its preparation method, and a catalytic reforming method. Background Technology
[0002] Catalytic reforming processes hydrocarbon molecules in naphtha into aromatics, hydrogen, and high-octane gasoline components, and is one of the main technologies in the modern petrochemical industry. Catalytic reforming is widely used to improve the grade of heavy gasoline, where hydrocarbons (alkanes and cycloalkanes) with 6-12 carbon atoms per molecule are reformed to produce aromatics or branched alkanes. The reforming reaction is carried out at high temperature (500°C) and low to medium pressure (3.5 × 10⁻⁶). 5 ~25×10 5 The process is carried out in the presence of a catalyst and a pressure (Pa). Catalytic reforming produces oils that can be used to increase the octane number of oil components. The reformed oils are mainly composed of C5... + The process produces hydrocarbon compounds (containing at least 5 carbon atoms). It also generates H2, fuel gas (formed from C1-C2 hydrocarbons), and liquefied petroleum gas (formed from C3-C4 hydrocarbons). Furthermore, coke is formed by aromatic ring condensation and deposited on the active sites of the catalyst.
[0003] In catalytic reforming, competing reactions occur simultaneously, including the dehydrogenation of cyclohexane to aromatics, the dehydrogenation and isomerization of alkylcyclohexane to aromatics, and the dehydrogenation and cyclization of cycloalkanes to aromatics. In these reactions, the production of light hydrocarbons through hydrocracking reduces gasoline yield, coking accelerates catalyst deactivation, and frequent catalyst regeneration increases operating costs. Therefore, developing highly selective catalytic reforming catalysts and processes with low coking rates has always been a goal.
[0004] In industrial reforming catalysts, the platinum content is typically a few parts per thousand. To provide sufficient metal centers, the dispersion state of platinum on Al₂O₃ is crucial in determining catalyst performance. To improve the performance of Pt / Al₂O₃ catalysts, other metals are often used as promoters to modify the metal and acid centers, further enhancing the catalyst's activity, stability, and selectivity, and extending its lifetime. Therefore, the influence and mechanism of these promoters on the dispersion state, microstructure, metallic function, and acidic function of platinum support are key scientific questions requiring further research.
[0005] Designing a catalyst for catalytic reforming reactions that allows platinum to be better dispersed on the support, thereby improving catalytic selectivity and resistance to coking, and avoiding frequent regeneration or eventual deactivation of the catalyst due to coking during use, is a pressing technical problem that needs to be solved. Summary of the Invention
[0006] This invention provides a supported catalyst, a preparation method, and a catalytic reforming method to improve the selectivity and anti-coking ability of the catalyst in the catalytic reforming reaction.
[0007] In a first aspect, the present invention provides a supported catalyst comprising a Sn-containing alumina support and an active component, wherein the active component comprises Pt, and the Pt is dispersed on the Sn-containing alumina support in the form of sub-nano clusters.
[0008] Optionally, the active component further includes Cl; based on the weight of the Sn-containing alumina support, the content of Pt is 0.01-5 wt%, the content of Sn is 0.1-10.0 wt%, and the content of Cl is 0.1-5 wt%; the atomic ratio of Pt to Sn is (0.01-20):1.
[0009] Optionally, the particle size of the sub-nano clusters is 0.5-2.0 nm; in the sub-nano clusters, the proportion of particles with a particle size of 0.7-1.3 nm is 80%-100%; preferably, the particle size of the sub-nano clusters is 1 nm.
[0010] In a second aspect, the present invention provides a method for preparing the above-mentioned supported catalyst, the method comprising the following steps: (1) adding a Pt precursor to a reducing organic solvent to obtain a first solution; (2) adjusting the pH of the first solution obtained from step (1) to 8-14, and then heating to obtain a second solution; (3) adding a Sn-containing alumina support to the second solution obtained from step (2) for impregnation, drying and calcination to obtain an intermediate product; (4) subjecting the intermediate product obtained from step (3) to water chlorine activation and reduction.
[0011] Optionally, in step (1): 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 includes at least one of 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 ethylene glycol, methanol, and formaldehyde; the concentration of Pt in the first solution is 0.25–5 mg / mL.
[0012] Optionally, in step (2): the pH value is adjusted by adding an alkaline solution to the first solution; the alkaline 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 water; preferably, the concentration of the ammonia water solution is 5-35 wt%.
[0013] Optionally, in step (3): the pore volume of the Sn-containing alumina support is 0.3–1.2 g / mL, and the specific surface area is 50–300 m². 2 / g; the drying temperature is 50-300℃ and the time is 2-48h.
[0014] Optionally, in step (4): the water chlorination activation includes heating the intermediate product obtained from step (3) 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 1-16h; and / or, the reduction is carried out in a reducing atmosphere containing hydrogen or carbon monoxide, the volume fraction of hydrogen or carbon monoxide is 10-100%; the reduction temperature is 250-700℃, and the time is 0.5-16h.
[0015] Thirdly, the present invention provides a method for naphtha catalytic reforming, wherein naphtha is reacted with a supported catalyst under naphtha catalytic reforming reaction conditions, wherein the supported catalyst is the aforementioned supported catalyst, or the supported catalyst prepared by the above method.
[0016] Optionally, the naphtha catalytic reforming reaction conditions include: a temperature of 360–600°C, a pressure of 0.1–1.0 MPa, and a liquid feed volume hourly space velocity of 1–20 h⁻¹. -1 The hydrogen / hydrocarbon volume ratio is 500-2000.
[0017] Optionally, the naphtha is selected from at least one of straight-run naphtha, hydrocracked naphtha, coking naphtha, catalytic cracked naphtha, and ethylene cracked naphtha; preferably, the naphtha contains alkanes, cycloalkanes, and aromatics; preferably, the hydrocarbons contained in the naphtha have 5-12 carbon atoms.
[0018] Beneficial effects:
[0019] In the supported catalyst of the present invention for catalytic reforming reaction, Pt is dispersed in the form of sub-nano clusters on a Sn-containing alumina support. The catalyst has better catalytic selectivity and anti-coking ability for naphtha catalytic reforming reaction, and can significantly improve the yield of liquid products. Attached Figure Description
[0020] Figure 1 HAADF-STEM image of the supported catalyst Pt / Al2O3-Sn prepared in Example 1.
[0021] Figure 2 The particle size distribution of Pt sub-nano clusters in the supported catalyst Pt / Al2O3-Sn prepared in Example 1 is shown.
[0022] Figure 3 HAADF-STEM image of the supported catalyst Pt / Al2O3-Sn prepared for Comparative Example 1. Detailed Implementation
[0023] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present application will become clearer and more apparent.
[0024] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.
[0025] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.
[0026] In a first aspect, the present invention provides a supported catalyst comprising a Sn-containing alumina support and an active component, wherein the active component comprises Pt, and the Pt is dispersed on the Sn-containing alumina support in the form of sub-nano clusters.
[0027] It should be noted that the supported catalyst described in this invention can be used for the catalytic reforming reaction of naphtha. In the supported catalyst of this invention, Pt is dispersed in the form of sub-nano clusters on the Sn-containing alumina support, thus providing better dispersibility of Pt. Furthermore, by improving the dispersibility of the active component Pt on the Sn-containing alumina support, the activity, stability, and selectivity of the catalyst can be effectively improved, and the formation of coke during catalyst use can be effectively reduced, thereby extending the catalyst's lifespan.
[0028] In one embodiment, the active component further includes Cl; based on the weight of the Sn-containing alumina support, the content of Pt is 0.01–5 wt%, the content of Sn is 0.1–10.0 wt%, and the content of Cl is 0.1–5 wt%; the atomic ratio of Pt to Sn is (0.01–20):1. Preferably, the content of Pt is 0.02–1 wt%, and the atomic ratio of Pt to Sn is (0.5–10):1.
[0029] It should be noted that in the supported catalyst of the present invention, Pt, as a metal center, can perform hydrogenation and dehydrogenation functions, Cl, as an acid center, can perform isomerization and acidic functions, and Sn can modify the metal center and acid center of the catalyst to improve the catalyst performance.
[0030] In one embodiment, the sub-nano clusters have a particle size of 0.5-2.0 nm; in the sub-nano clusters, the proportion of particles with a particle size of 0.7-1.3 nm is 80%-100%; preferably, the sub-nano clusters have a particle size of 1 nm.
[0031] It should be noted that, as a preferred embodiment, in the supported catalyst of the present invention, firstly, the active component Pt is selected to be dispersed in the form of sub-nano clusters on the surface of Sn-containing alumina support. At the same time, the content of Pt, Sn, Cl and the atomic ratio of Pt to Sn are comprehensively controlled. In particular, the proportion of sub-nano cluster particles with a particle size of 0.7-1.3 nm is 80% to 100%, thereby enabling the supported catalyst to achieve better catalytic selectivity and less coke formation.
[0032] In a second aspect, the present invention provides a method for preparing the above-mentioned supported catalyst, the method comprising the following steps: (1) adding a Pt precursor to a reducing organic solvent to obtain a first solution; (2) adjusting the pH of the first solution obtained from step (1) to 8-14, and then heating to obtain a second solution; (3) adding a Sn-containing alumina support to the second solution obtained from step (2) for impregnation, drying and calcination to obtain an intermediate product; (4) subjecting the intermediate product obtained from step (3) to water chlorine activation and reduction.
[0033] It should be noted that in the method for preparing the supported catalyst of the present invention, the first solution is a reducing organic solution of Pt precursor. After adjusting the pH value and heating in step (2), Pt exists in the form of sub-nano clusters in the second solution. Then, after the impregnation and post-treatment process in step (3), Pt is loaded onto the surface of the Sn-containing alumina support in the form of sub-nano clusters by electrostatic adsorption.
[0034] In one embodiment, step (1) involves adding the Pt precursor to the reducing organic solvent, which includes adding the Pt precursor to the first portion of the reducing organic solvent and then mixing it with the 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, dichlorocarbonyl platinum dichloride, dinitrodiaminoplatinum, tetranitroplatinic acid, and platinum acetylacetonate. During the preparation process, the concentration of Pt in the first solution is controlled to be 0.25–5 mg / mL. The concentration of Pt can refer to the concentration based on the mass of Pt. In one embodiment, the reducing organic solvent is one or more of ethylene glycol, methanol, and formaldehyde. In this application, the main function of the reducing organic solvent is to reduce metal ions in the solution to metal atoms, which then aggregate into nuclei, ultimately generating sub-nano clusters.
[0035] In the preparation process of this application, step (1) is carried out in an inert atmosphere, which is one or more of argon, nitrogen and helium.
[0036] It should be noted that in step (1), a certain amount of platinum metal precursor is added to a reducing organic solvent such as ethylene glycol and stirred for 5-15 minutes to make it uniformly mixed to obtain the first solution. Alternatively, a certain amount of the reducing organic solution of the platinum metal precursor is added to a certain volume of reducing organic solvent and mixed uniformly to obtain the first solution. When preparing the first solution, a reducing organic solvent such as ethylene glycol is selected as the solvent. Combined with the processing in step (2), Pt in the second solution can exist in the form of sub-nano clusters. Then, through the impregnation and post-treatment process in step (3), Pt can be loaded onto the surface of the Sn-containing alumina support in the form of sub-nano clusters by electrostatic adsorption.
[0037] It should be noted that, as a preferred embodiment, the reducing organic solvent is ethylene glycol.
[0038] In another embodiment, step (2) involves adjusting the pH value by adding one or more alkaline solutions, such as ammonia, urea, potassium hydroxide, or sodium hydroxide, to the first solution. Preferably, the alkaline solution is ammonia, thus avoiding the introduction of elements potentially detrimental to catalyst activity. Preferably, the concentration of the ammonia solution is 5–35 wt%, such as 10 wt%. In one embodiment, after pH adjustment, heating is performed, including heating the pH-adjusted solution to 120–180°C and stirring for 2–8 hours, followed by cooling to room temperature. In one embodiment, the cooling is performed in an inert atmosphere, which is one or a mixture of two or more of argon, nitrogen, and helium.
[0039] It should be noted that when adjusting the pH value to the target value by adding ammonia or other substances to the first solution, the pH-adjusted solution can be heated by means of an oil bath, water bath, sand bath, etc., while stirring.
[0040] It should be noted that, as a preferred embodiment, the pH value is adjusted by adding ammonia to the first solution.
[0041] In one embodiment, in step (3): the pore volume of the Sn-containing alumina support is 0.3–1.2 g / mL, and the specific surface area is 50–300 m² / mL. 2 / g. The impregnation can be carried out in a closed container at a temperature of 10–80°C for 10–100 h. After impregnation, a drying process is performed at a temperature of 50–300°C for 2–48 h.
[0042] Subsequently, the catalyst intermediate is subjected to water chlorine activation treatment. In one embodiment, step (4) involves heating the intermediate obtained from step (3) 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°C, and the time is 1–16 h.
[0043] Following chlorination activation, a reduction process is performed. This reduction is carried out in a reducing atmosphere containing hydrogen or carbon monoxide. The volume fraction of hydrogen or carbon monoxide is 10–100%. The reduction temperature is 250–700°C, and the time is 0.5–16 hours.
[0044] It should be noted that by placing the intermediate product in air containing HCl and H2O for water chlorination activation, the chlorine content and acidic site density in the catalyst can be increased, thereby giving the prepared supported catalyst better catalytic selectivity.
[0045] Thirdly, the present invention provides a method for naphtha catalytic reforming, wherein naphtha is reacted with a supported catalyst under naphtha catalytic reforming reaction conditions, wherein the supported catalyst is the aforementioned supported catalyst or the supported catalyst prepared by the above method.
[0046] As described above, in the supported catalyst of the present invention, Pt is dispersed in the form of sub-nano clusters on the surface of the Sn-containing alumina support, thus Pt has better dispersibility. Therefore, when naphtha catalytic reforming reaction is carried out in the presence of the above-mentioned supported catalyst, better catalytic selectivity can be obtained, the aromatic content in the liquid product can be increased, and the coking rate can be reduced.
[0047] According to one embodiment, the naphtha catalytic reforming reaction conditions include:
[0048] The temperature is 360–600℃, the pressure is 0.1–1.0 MPa, and the liquid feed volumetric hourly space velocity is 1–20 h⁻¹. -1 The hydrogen / hydrocarbon volume ratio is 500-2000.
[0049] It should be noted that the hydrogen / hydrocarbon volume ratio can also be 200-2000. Based on the catalytic effect of the supported catalyst described above, naphtha catalytic reforming under the above conditions can further achieve better catalytic selectivity, increase the aromatic content in the liquid products, and reduce the rate of coking.
[0050] According to one embodiment, the naphtha is selected from at least one of straight-run naphtha, hydrocracked naphtha, coking naphtha, catalytic cracked naphtha, and ethylene cracked naphtha; preferably, the naphtha contains alkanes, cycloalkanes, and aromatics, and the hydrocarbons contained in the naphtha have 5-12 carbon atoms.
[0051] The initial boiling point of naphtha, determined according to 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 invention is preferably carried out in a sulfur-free or low-sulfur environment, and the sulfur content of the naphtha can be no higher than 1.0 μg / g, preferably no higher than 0.5 μg / g. To achieve the required sulfur content, the naphtha can be desulfurized using various methods before catalytic reforming, including adsorption desulfurization and catalytic desulfurization. These methods are well known to those skilled in the art and will not be described in detail here.
[0052] The present invention will be further described in detail below through examples.
[0053] Carrier preparation example
[0054] 137.4 g of pseudoboehmite powder (manufactured by Condea GmbH, Germany, grade SB, alumina content 72.8 wt%), 0.60 g of SnCl2·2H2O, and 350 g of deionized water were mixed and stirred for 0.5 h. 14 g of 22 wt% nitric acid solution was added dropwise, and the mixture was stirred at 20 °C for 2 h. Then, 30 g of kerosene and 3 g of fatty alcohol polyoxyethylene ether were added, and the mixture was drop-formed into spheres in an oil-ammonia column. The wet spheres were cured in ammonia water for 1 h, then filtered, rinsed with deionized water, dried at 60 °C for 6 h, dried at 120 °C for 10 h, and calcined at 600 °C for 4 h to obtain a Sn-containing γ-Al2O3 support. The specific surface area of the support was 210 m² / g as measured by N2 adsorption (BET). 2 / g, pore volume is 0.6mL / g.
[0055] Example 1
[0056] Under Ar atmosphere protection, 22.2 mL of a chloroplatinic acid ethylene glycol solution with a platinum content of 4.5 mg / mL was mixed with 200 mL of ethylene glycol. A 25 wt% ammonia solution was added to adjust the pH to 12. After stirring for 30 minutes until homogeneous, the mixture was transferred to an oil bath and stirred at 150 °C for 3 hours. The mixture was then cooled to room temperature under inert atmosphere protection. The prepared Sn-containing γ-Al₂O₃ support was then added to the mixture and stirred for 3 hours until homogeneous. The catalyst was washed and filtered at room temperature. The filtered product was then dried in a 120 °C oven for 12 hours, followed by calcination at 500 °C in air for 3 hours. The calcined sample was then activated with chlorine in air containing HCl and water at 450 °C for 4 hours. Finally, it was reduced in hydrogen at 450 °C for 4 hours to obtain reduced catalyst A.
[0057] Example 2
[0058] Under Ar atmosphere protection, 22.2 mL of a chloroplatinic acid ethylene glycol solution with a platinum content of 4.5 mg / mL was mixed with 200 mL of ethylene glycol. A 25 wt% ammonia solution was added to adjust the pH to 8. After stirring for 30 minutes until homogeneous, the mixture was transferred to an oil bath and stirred at 150 °C for 3 hours. The mixture was then cooled to room temperature under inert atmosphere protection. The prepared Sn-containing γ-Al₂O₃ support was then added to the mixture and stirred for 3 hours until homogeneous. The catalyst was washed and filtered at room temperature. The filtered product was then dried in a 120 °C oven for 12 hours, followed by calcination at 500 °C in air for 3 hours. The calcined sample was then activated with chlorine at 450 °C by passing HCl and water through air for 4 hours. Finally, it was reduced in hydrogen at 450 °C for 4 hours to obtain reduced catalyst B.
[0059] Example 3
[0060] Under Ar atmosphere protection, 22.2 mL of a chloroplatinic acid ethylene glycol solution with a platinum content of 4.5 mg / mL was mixed with 200 mL of ethylene glycol. A 25 wt% ammonia solution was added to adjust the pH to 14. After stirring for 30 minutes until homogeneous, the mixture was transferred to an oil bath and stirred at 150 °C for 3 hours. The mixture was then cooled to room temperature under inert atmosphere protection. The prepared Sn-containing γ-Al₂O₃ support was then added to the mixture and stirred for 3 hours until homogeneous. The catalyst was washed and filtered at room temperature. The filtered product was then dried in a 120 °C oven for 12 hours, followed by calcination at 500 °C in air for 3 hours. The calcined sample was then activated with chlorine at 450 °C by passing HCl and water through air for 4 hours. Finally, it was reduced in hydrogen at 450 °C for 4 hours to obtain the reduced catalyst C.
[0061] Example 4
[0062] Under Ar atmosphere protection, 33.3 mL of a chloroplatinic acid ethylene glycol solution with a platinum content of 4.5 mg / mL was mixed with 200 mL of ethylene glycol. A 25 wt% ammonia solution was added to adjust the pH to 12. After stirring for 30 minutes until homogeneous, the mixture was transferred to an oil bath and stirred at 150 °C for 3 hours. The mixture was then cooled to room temperature under inert atmosphere protection. The prepared Sn-containing γ-Al₂O₃ support was then added to the mixture and stirred for 3 hours until homogeneous. The catalyst was washed and filtered at room temperature. The filtered product was then dried in a 120 °C oven for 12 hours, followed by calcination at 500 °C in air for 3 hours. The calcined sample was then activated with chlorine at 450 °C by passing HCl and water through air for 4 hours. Finally, it was reduced in hydrogen at 450 °C for 4 hours to obtain the reduced catalyst D.
[0063] Comparative Example 1
[0064] The specific preparation method includes the following steps: 22.2 mL of a chloroplatinic acid aqueous solution with a platinum content of 4.5 mg / mL is added to 200 mL of deionized water. After stirring for 30 minutes until homogeneous, the Sn-containing γ-Al₂O₃ support prepared above is added to the mixture. The mixture is stirred for 3 hours until homogeneous, then the filtrate is evaporated to dryness and dried at 120℃ for 12 hours. Subsequently, it is calcined at 500℃ in air for 3 hours. The calcined sample is then activated with chlorine by passing air containing HCl and water through it at 450℃ for 4 hours. Finally, it is reduced in hydrogen at 450℃ for 4 hours to obtain the reduced catalyst a.
[0065] Test Example 1
[0066] Catalyst evaluation was conducted on a microreactor 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 contained a mixture of 2 mL of catalyst and 6 mL of quartz sand (catalysts AD and a, respectively). Naphtha was used as the feedstock to evaluate the catalysts. The composition of the naphtha is shown in Table 1 (in Table 1, IBP represents the initial boiling point; EBP represents the final boiling point; m(P), m(N), and m(A) represent the mass percentages of alkane, cycloalkanes, and aromatics, respectively). The evaluation conditions were: reaction temperature 500℃, reaction pressure 0.35 MPa, hydrogen / hydrocarbon volume ratio 800, and liquid hourly space velocity (LHSV) 2.0 h⁻¹. -1The average reaction results after a cumulative reaction time of 100 h are shown in Table 2. Both raw materials and products were analyzed and sampled using Agilent gas chromatography with an FID detector to measure the mass fractions of components such as benzene and toluene in the raw materials and / or products. Bed temperature was also measured to investigate the change in catalyst selectivity with reaction time. The amount of catalyst coke after the reaction was determined using an EMIA-820V infrared sulfur-carbon analyzer from HORIBA Corporation (Japan), and the results are listed in Table 2.
[0067] C of catalyst 5+ Liquid product yield (Y) C5+液体产物收率 Calculate according to formula (1):
[0068] Y C5+液体产物收率 = The sum of the mass fractions of C5+ in the product……………(1).
[0069] Aromatic content in liquid products (X) 芳烃含量 Calculate according to formula (2):
[0070] X 芳烃含量 =X 苯 +X 甲苯 +X 混合二甲苯 +X C9+芳烃 ……………………(2).
[0071] X 苯 X 甲苯 X 混合二甲苯 and X C9+芳烃 The mass fractions of benzene, toluene, mixed xylenes, and C9+ aromatics in the feed liquid are indicated respectively.
[0072] Aromatic yield of catalyst (Y) 芳烃产率 Calculate according to formula (3):
[0073] Y 芳烃产率 =Y C5+液体产物收率 ×X 芳烃含量 ×100%……………………(3).
[0074] Octane number yield of catalyst (Q) 辛烷值收率 Calculate according to formula (4):
[0075] 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).
[0076] Liquid product research method octane number (R) 液体产物研究法辛烷值 ) was measured by the near-infrared method.
[0077] Table 1. Properties of naphtha feedstock
[0078]
[0079] Table 2 Evaluation of Catalyst Reaction Performance
[0080]
[0081]
[0082] As can be seen from the data in Examples 1-4 and Comparative Example 1 in Table 2, the supported catalyst of the present invention can improve the yield of liquid products, increase the aromatic content in liquid products, increase the aromatic yield, increase the octane number yield, and reduce the amount of carbon deposits in naphtha catalytic reforming.
[0083] In Comparative Example 1, the ethylene glycol in Example 1 was removed, and Pt was directly impregnated on an alumina support. When the platinum loading was the same as in Example 1, the resulting catalyst exhibited low selectivity for naphtha reforming and was prone to coking and deactivation. Comparative Example 1 and Example 1 together demonstrate that the method described in this invention is key to preparing highly dispersed, highly selective, and anti-coking Pt sub-nano cluster catalysts.
[0084] As shown in Table 1, compared with the catalyst prepared in the comparative example, the catalyst of this invention exhibits a higher yield of liquid products and a lower amount of coking after the reaction. In summary, the catalyst of this invention demonstrates good selectivity and anti-coking ability in naphtha catalytic reforming, and can significantly improve the yield of liquid products. Furthermore, the catalyst exhibits stable structure and is not prone to agglomeration during use.
[0085] Test Example 2
[0086] Catalyst A prepared in Example 1 and catalyst a obtained in Comparative Example 1 were examined using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The resulting HAADF-STEM images are shown below. Figure 1 and Figure 3 The particle size distribution diagram of Pt sub-nano clusters in the catalyst of Example 1 is shown below. Figure 2 As shown.
[0087] pass Figure 1 It can be seen that in the catalyst prepared by the method of this application, platinum is dispersed or anchored on the tin-containing alumina support in the form of sub-nanometer clusters. Figure 2 It can be seen that in the catalyst prepared in Example 1, the particle size distribution of Pt sub-nano clusters is about 0.5-2.0 nm, mainly distributed in 0.7-1.3 nm; the proportion of particles with a particle size of 0.7-1.3 nm is 80% to 100%.
[0088] Figure 3It can be seen that the particle size distribution of Pt in the catalyst of Comparative Example 1 is very irregular. When the Pt content is the same, there are fewer visible particles and a lot of noise.
[0089] Test Example 3
[0090] The metal element content in the catalysts of the above examples and comparative examples was determined by X-ray fluorescence method, and the chlorine content was determined by electrode method. The results are shown in Table 3.
[0091] Table 3
[0092]
[0093] In the description of this application, it should be noted that the terms "upper", "lower", "inner", "outer", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship in the working state of this application. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.
[0094] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.
[0095] The present application has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and illustrative. Various substitutions and modifications can be made to the present application based on these embodiments, all of which fall within the protection scope of the present application.
Claims
1. A supported catalyst, characterized in that, The supported catalyst includes a Sn-containing alumina support and an active component, wherein the active component includes Pt, and Pt is dispersed on the Sn-containing alumina support in the form of sub-nano clusters. The active component further includes Cl, and the content of Cl is 0.1 to 5 wt% based on the weight of the Sn-containing alumina support. The sub-nano clusters have a particle size of 0.5-2.0 nm; In the aforementioned sub-nanometer clusters, particles with a diameter of 0.7-1.3 nm account for 80% to 100% of the total. The supported catalyst is prepared by the following method: (1) Add the Pt precursor to a reducing organic solvent to obtain the first solution; (2) Adjust the pH of the first solution obtained from step (1) to 8-14, and then heat it to obtain the second solution; (3) The Sn-containing alumina support is added to the second solution obtained from step (2) for impregnation, drying and calcination to obtain an intermediate product; (4) The intermediate product obtained from step (3) is activated and reduced by water chlorine.
2. The supported catalyst according to claim 1, characterized in that, The active component also includes Cl; Based on the weight of the Sn-containing alumina support, the Pt content is 0.01~5 wt%, the Sn content is 0.1~10.0 wt%, and the Cl content is 0.1~5 wt%. The atomic ratio of Pt to Sn is (0.01~20):
1.
3. The supported catalyst according to claim 1, characterized in that, The sub-nano clusters have a particle size of 1 nm.
4. A method for preparing the supported catalyst according to any one of claims 1-3, characterized in that, The method includes the following steps: (1) Add the Pt precursor to a reducing organic solvent to obtain the first solution; (2) Adjust the pH of the first solution obtained from step (1) to 8-14, and then heat it to obtain the second solution; (3) The Sn-containing alumina support is added to the second solution obtained from step (2) for impregnation, drying and calcination to obtain an intermediate product; (4) The intermediate product obtained from step (3) is activated and reduced by water chlorine.
5. The method according to claim 4, 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 includes at least one of 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 ethylene glycol, methanol, and formaldehyde; The concentration of Pt in the first solution is 0.25~5 mg / mL.
6. The method according to claim 5, characterized in that, In step (2): The pH value was adjusted by adding an alkaline solution to the first solution; The alkaline solution is selected from one or more of ammonia water, urea solution, potassium hydroxide solution or sodium hydroxide solution.
7. The method according to claim 6, characterized in that, The alkaline solution is selected from ammonia water.
8. The method according to claim 6, characterized in that, The concentration of the ammonia solution is 5 to 35 wt%.
9. The method according to claim 6, characterized in that, In step (3): The Sn-containing 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.
10. The method according to claim 9, characterized in that, In step (4): The water chlorination activation includes heating the intermediate product obtained from step (3) 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 in a reducing atmosphere containing hydrogen or carbon monoxide, wherein the volume fraction of hydrogen or carbon monoxide is 10-100%. The reduction temperature is 250~700 ℃, and the time is 0.5~16 h.
11. A method for naphtha catalytic reforming, characterized in that, Under naphtha catalytic reforming reaction conditions, naphtha is brought into contact with a supported catalyst for reaction, wherein the supported catalyst is the supported catalyst according to any one of claims 1-3, or the supported catalyst prepared by the method according to any one of claims 4-10.
12. The method according to claim 11, characterized in that, The naphtha 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.
13. The method according to claim 12, 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.
14. The method according to claim 13, characterized in that, The naphtha contains alkanes, cycloalkanes, and aromatics.
15. The method according to claim 13, characterized in that, The naphtha contains hydrocarbons with 5-12 carbon atoms.