Preparation method and application of naphtha catalytic reforming catalyst

Abstract

The invention provides a preparation method and application of a naphtha catalytic reforming catalyst, and the preparation method comprises the following steps: (1) modifying a Y molecular sieve with an alkali metal alcohol solution or an alkaline earth metal alcohol solution to obtain an alkali metal or alkaline earth metal modified non-acidic Y molecular sieve; (2) putting the molecular sieve prepared in the step (1) into a mixed solution of SnCl4 and acetone, stirring, drying and roasting to obtain a Sn-modified non-acidic Y molecular sieve; and (3) carrying out Pt loading on the Sn-modified non-acidic Y molecular sieve prepared in the step (2) by using a Pt source, and then carrying out reduction treatment to obtain the Pt-based catalyst with uniformly distributed Pt particles. According to the invention, a non-acidic molecular sieve is used as a carrier, and a Pt-based catalyst is prepared by optimizing a Pt loading mode and adjusting catalyst reduction conditions. The prepared Pt-based catalyst shows excellent reaction activity and aromatic hydrocarbon selectivity in aromatization of C6-C10 alkanes.

Description

Technical Field

[0001] The invention belongs to the field of coal / petrochemical industry, and particularly relates to a preparation method of a naphtha catalytic reforming catalyst and application thereof. Technical Background

[0002] Producing organic liquid feedstocks from non-petroleum-based (biomass, coal) carbon-containing resources is an effective means of addressing the shortage of domestic petroleum resources. Indirect coal liquefaction technology converts the syngas from gasified carbon-containing resources into petrochemical products such as gasoline and diesel. However, this product contains a large amount of low-octane linear alkanes, which seriously affect gasoline quality. Alkane aromatization technology, which converts linear alkanes into aromatics with higher added value and octane numbers, is of great significance for improving gasoline quality and optimizing the product mix of coal-to-liquids. Consequently, this technology has attracted widespread attention in both industry and academia.

[0003] As the core of catalytic reforming technology, catalysts are the key to influencing reaction activity and product distribution. Bimetallic or multimetallic catalysts composed of alumina-supported Pt and additives (Sn, Ir, Re, etc.) have received widespread attention in crude oil naphtha processing. However, for Fischer-Tropsch naphtha with a high content of straight-chain alkanes, commercial Pt / Al2O3 catalysts are prone to side reactions such as cracking and isomerization, resulting in low selectivity for aromatic products. Han (Applied Catalysis A:General, Ce-introduced effects on modification of acidity and Pt electronic states on Pt-Sn / γ-Al2O3 catalysts for catalytic reforming, 2021, 617, 118116-118128) used C7 alkanes as reaction raw materials and conducted research on Pt / Al2O3 catalysts. It was found that its selectivity for small molecule alkanes was as high as 40%, while the selectivity for aromatics was only 31.7%.

[0004] Compared to traditional Pt / Al2O3 catalysts, monofunctional Pt / KL catalysts exhibit superior catalytic performance in the aromatization of medium- and long-chain (C6-C7) alkanes. CN115212918A discloses the preparation and application of a Zn-regulated KL molecular sieve-supported Pt catalyst. The Pt / ZnKL catalyst obtained in this patent achieves aromatics selectivity of up to 90% in the aromatization of n-heptane. CN101746774A discloses a method for synthesizing Sn-containing KL molecular sieves. After loading Pt, the catalyst exhibits superior aromatics selectivity and stability in the aromatization of n-hexane. However, Kyungho et al. (Journal of Catalysis, Hierarchically micro- / mesoporous Pt / KL for alkane aromatization: Synergistic combination of high catalytic activity and suppressed hydrogenolysis, 2016, 340, 66-75) found that the alkane aromatization performance of Pt / KL is related to the molecular size of the alkane. It has excellent performance in the aromatization of C6 and C7 alkanes, but when C8 alkane is used as the reaction raw material, the aromatic selectivity (≤60%) and stability of the Pt / KL catalyst are greatly reduced.

[0005] Compared with Pt / KL catalysts, Rangel (Applied Catalysis A: General, Ethylbenzene production over platinum catalysts supported on modified KY zeolites, 2010, 386, 201-210) and Liu (Catalysis Today, Preparation, characterization and naphthaaromatization performance of the catalytic reforming catalyst Pt / MY (M = Mg, Baor Ce), 2020, 353, 146-152) and other research groups pointed out that Pt-based catalysts supported on alkaline earth metal-modified Y molecular sieves can achieve aromatic selectivity of more than 80% in the aromatization of medium and long-chain alkanes, especially C8 alkanes. However, the acidic sites on the surface of the Y molecular sieve of Rangel and Liu's Pt-based catalysts lead to a wide variety of C8 aromatics, and the contents of ethylbenzene, m-xylene and o-xylene in the obtained C8 aromatics are all high (the ratio is about 1:1:1), which increases the difficulty of separating the desired products (such as ethylbenzene and o-xylene). In addition, the Pt-based catalysts of Rangel and Liu have poor stability, and the reduction rate of raw material conversion after 4 hours of operation is as high as 25%. CN114956115A discloses a metal-modified Y-type molecular sieve and a preparation method thereof. The patent mentions that by metal-modifying the Y molecular sieve, some acid centers can be eliminated to reduce the adverse effects of carbon deposition on the reaction, thereby improving the stability of the Y-type molecular sieve in various reactions. However, the catalyst prepared by the method of the patent is mainly suitable for catalytic cracking and alkylation, and is difficult to be applied to the aromatization reaction of medium and long-chain straight-chain alkanes (especially C8 alkanes).

[0006] Considering that medium- and long-chain linear alkanes are important components of Fischer-Tropsch naphtha, it is urgent to develop a catalytic system suitable for the aromatization of medium- and long-chain linear alkanes. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for preparing a naphtha catalytic reforming catalyst and its application. The present invention uses a non-acidic molecular sieve as a carrier, optimizes the Pt loading method and adjusts the catalyst reduction conditions to prepare a Pt-based catalyst. The prepared Pt-based catalyst has a high activity in C6-C 10 It exhibits excellent reactivity and aromatic selectivity in the aromatization of alkanes (preferably C8 alkanes).

[0008] In a first aspect, the present invention provides a method for preparing a naphtha catalytic reforming catalyst, the method comprising the following steps:

[0009] (1) Modifying the Y molecular sieve with an alkali metal alcohol solution or an alkaline earth metal alcohol solution to obtain an alkali metal or alkaline earth metal modified non-acidic Y molecular sieve;

[0010] (2) placing the molecular sieve prepared in step (1) in a mixture of SnCl4 and acetone, stirring, drying and calcining to obtain a Sn-modified non-acidic Y molecular sieve;

[0011] (3) After the Sn-modified non-acidic Y molecular sieve prepared in step (2) is loaded with Pt using a Pt source, a reduction treatment is performed to obtain a Pt-based catalyst with uniformly distributed Pt particles.

[0012] In a second aspect, the present invention provides a Pt-based catalyst obtained by the preparation method described in the first aspect.

[0013] In a third aspect, the present invention provides use of the Pt-based catalyst described above in catalytic reforming of naphtha.

[0014] In a fourth aspect, the present invention provides a method for catalytic reforming of naphtha, comprising catalytically reforming naphtha using the Pt-based catalyst described above.

[0015] Beneficial effects

[0016] 1. The preparation method of the non-acidic molecular sieve provided by the present invention is simple to operate, takes a short time, and can adjust the acidity of the molecular sieve by changing the concentration of the alkaline alcohol solution.

[0017] 2. The Pt-based catalyst provided by the present invention exhibits excellent aromatization performance in the aromatization of medium and long-chain alkanes and has certain industrial application value.

[0018] 3. The Pt-based catalysts in the prior art (such as the Pt-based catalysts reported by Rangel and Liu et al.) produce a wide variety of C8 aromatics when catalyzing the aromatization of medium- and long-chain alkanes, and the separation of desired products (such as ethylbenzene and o-xylene) is difficult. However, due to the absence of acidic sites in the Pt-based catalysts of the present invention, the C8 aromatics obtained when catalyzing the aromatization of medium- and long-chain alkanes are mainly ethylbenzene and o-xylene, and the total proportion of the two in the C8 aromatics can reach more than 95%, and the ratio is about 1:1, with excellent distribution of C8 aromatics.

[0019] 4. The stability of the Pt-based catalysts in the prior art is poor. For example, the Pt-based catalyst reported by Rangel and Liu et al. operated for 250 minutes and the raw material conversion rate dropped from 100% to 75%; while the Pt-based catalyst of the present invention can operate stably for more than 12 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are a part of the specification and together with the detailed description, provide further explanation of the present invention but are not intended to limit the present invention.

[0021] Figure 1 The pyridine adsorption infrared spectrum (Py-IR) spectra of the molecular sieves in the comparative example and Example 4 of the present invention are shown.

[0022] Figure 2 This is a high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) image of the catalyst in Example 1 of the present invention.

[0023] Figure 3 This is the HAADF-STEM image of the catalyst in Example 2 of the present invention.

[0024] Figure 4 This is the HAADF-STEM image of the catalyst in Example 3 of the present invention.

[0025] Figure 5 This is the HAADF-STEM image of the catalyst in Example 4 of the present invention.

[0026] Figure 6 This is the stability evaluation result of the catalyst in Example 4 of the present invention. DETAILED DESCRIPTION

[0027] The specific embodiments of the present invention are described in detail below. The specific embodiments described herein are only used to illustrate and explain the present invention, but are not used to limit the present invention.

[0028] In the present invention, unless otherwise specified, the term "naphtha" refers to a hydrocarbon mixture having a boiling point of about 30°C to about 240°C, preferably C6-C 10 Alkanes (such as C6-C 10 More preferably, one or more of C8 alkanes (e.g., C8 straight-chain alkanes).

[0029] In the present invention, unless otherwise specified, the term "catalytic reforming of naphtha" mainly refers to "aromatization of alkanes", which refers to the aromatization of alkanes (especially C6-C 10 The catalytic reaction process of converting straight-chain alkanes into aromatic hydrocarbons.

[0030] In the present invention, the term "Y molecular sieve" is also referred to as "Y-type molecular sieve", which has a three-dimensional pore structure and large pore size characteristics and is suitable for catalytic reforming reactions of medium and long chain alkanes.

[0031] In the present invention, the term "non-acidic molecular sieve" refers to a molecular sieve that has been treated with chemical means (such as alkali metal modification) to remove or passivate the acid sites (including acid and Lewis acid sites).

[0032] In the present invention, the term "modification" refers to the process of changing the acid-base properties, structural characteristics or metal affinity of the molecular sieve surface or pores by chemical treatment.

[0033] In the present invention, the term "calcination" refers to the process of heating a solid material under a controlled atmosphere (usually air), usually at a temperature ranging from 200 to 800°C, with the purpose of removing volatile components (such as organic matter, solvents, moisture, etc.) in the material, promoting the decomposition, structural setting or crystallization of the precursor, thereby obtaining a material structure with higher thermal stability or catalytic activity.

[0034] In the present invention, the term "precursor solution" refers to a uniform solution formed by dissolving a metal precursor (such as a metal salt, an organometallic compound, etc.) in an appropriate solvent, which is used to introduce the metal component into the support material to achieve loading, doping or modification.

[0035] In the present invention, the term "impregnation method" refers to a method in which a pre-prepared metal precursor solution is brought into contact with a solid support, the metal precursor is adsorbed or dispersed on the surface or in the pores of the support, and a supported catalyst is obtained through steps such as drying and calcination.

[0036] In the present invention, the term "atomic layer deposition (ALD)" refers to a preparation technology that can control the deposition of materials at the atomic scale. By alternately introducing two or more gaseous precursors, a layer-by-layer self-limiting reaction can occur on the substrate surface, thereby achieving high-precision controlled deposition of components such as metals or oxides.

[0037] In the present invention, the term "Pt-based catalyst" refers to a material system with metallic platinum (Pt) as the catalytically active component. Platinum can exist in the form of metal or its oxide and is dispersed on the surface or in the pores of the carrier, and has good catalytic activity and selectivity.

[0038] In the present invention, the term "Pt loading" refers to the process of introducing a Pt-containing precursor compound into the surface or pores of a molecular sieve serving as a carrier by physical adsorption, impregnation, chemical deposition, etc., and then subjecting the compound to treatment steps such as drying, calcination, and reduction, so that Pt is dispersed on the surface or in the pores of the carrier in the form of a metal or its oxide.

[0039] In the present invention, the term "Pt source" refers to a metal precursor compound that provides platinum element, usually an inorganic salt or an organic metal complex of platinum.

[0040] In the present invention, the term "part" or "a portion" refers to some of the object modified by the term, for example, it can represent any value within the range of greater than 0% to less than 100% relative to the entire object modified by the term.

[0041] In the present invention, room temperature refers to 20 to 25°C.

[0042] In some embodiments, the present invention provides a method for preparing a naphtha catalytic reforming catalyst, the method comprising the following steps:

[0043] (1) Modifying the Y molecular sieve with an alkali metal alcohol solution or an alkaline earth metal alcohol solution to obtain an alkali metal or alkaline earth metal modified non-acidic Y molecular sieve;

[0044] (2) placing the molecular sieve prepared in step (1) in a mixture of SnCl4 and acetone, stirring, drying and calcining to obtain a Sn-modified non-acidic Y molecular sieve;

[0045] (3) After the Sn-modified non-acidic Y molecular sieve prepared in step (2) is loaded with Pt using a Pt source, a reduction treatment is performed to obtain a Pt-based catalyst.

[0046] In a preferred embodiment, in step (1), the modification with an alkali metal alcohol solution or an alkaline earth metal alcohol solution comprises: stirring the Y molecular sieve and the alkali metal alcohol solution or the alkaline earth metal alcohol solution at room temperature, centrifuging the stirred mixed solution to obtain a centrifuged solid and a supernatant, washing the centrifuged solid with a washing agent, repeating the centrifugation and washing operations until the obtained supernatant is neutral, and drying and calcining the washed solid to obtain an alkali metal or alkaline earth metal modified non-acidic Y molecular sieve.

[0047] In a preferred embodiment, in step (1), the silicon-aluminum ratio of the Y molecular sieve is (3-60):1, for example, (5-60):1, (10-50):1, (20-50):1, (30-40):1, or (20-30):1. In the present invention, the "silicon-aluminum ratio of the Y molecular sieve" refers to the atomic ratio of silicon to aluminum contained in the Y molecular sieve.

[0048] In the present invention, the alkali metal alcohol solution is a mixture of an alkali metal hydroxide and a C1-C4 alcohol, and the alkaline earth metal alcohol solution is a mixture of an alkaline earth metal hydroxide and a C1-C4 alcohol.

[0049] In a preferred embodiment, in step (1), the alkali metal hydroxide or alkaline earth metal hydroxide includes one or more of potassium hydroxide (KOH), sodium hydroxide (NaOH), magnesium hydroxide (Mg(OH)2), and barium hydroxide (Ba(OH)2), and the small molecule alcohol includes one or more of anhydrous methanol, anhydrous ethanol, and anhydrous isopropanol.

[0050] In a preferred embodiment, in step (1), the mass ratio of the alkali metal hydroxide or alkaline earth metal hydroxide to the Y molecular sieve is 1:(3-50), preferably 1:(3-30), more preferably 1:(3-20), for example, 1:(3-18), 1:(3-17), 1:(3-15), 1:(3-12), 1:(3-8), 1:(3-7), or 1:(3-6).

[0051] In a preferred embodiment, in step (1), the mass volume ratio of the alkali metal hydroxide or alkaline earth metal hydroxide to the C1-C4 alcohol in g / mL is 1:(50-400), preferably 1:(50-350), more preferably 1:(60-320), for example, 1:(70-320), 1:(75-320), 1:(75-300), 1:(75-250), 1:(75-210), 1:(75-200), 1:(75-180), 1:(75-170), or 1:(75-165).

[0052] In a preferred embodiment, in step (1), the stirring time is 10-100 min, such as 20-100 min, 20-90 min, 50-90 min, 60-80 min.

[0053] In a preferred embodiment, in step (1), for each centrifugal separation, the centrifugal speed is 10000-11000 rpm, and the centrifugal time is 6-7 min.

[0054] In a preferred embodiment, in step (1), the washing reagent is one or more of anhydrous methanol, anhydrous ethanol, and anhydrous isopropanol, and the amount of the washing reagent used each time is 120-130 g.

[0055] In the present invention, in step (1), "repeating the centrifugal separation and washing operations until the supernatant obtained is neutral" means performing the centrifugal separation and washing operations multiple times until the supernatant obtained by the last washing is neutral.

[0056] In a preferred embodiment, in step (1), the drying temperature is 80-120°C (e.g., 90-120°C, 80-105°C, 90-105°C), and the drying time is 5-12h (e.g., 6-12h, 8-12h, 8-10h).

[0057] In a preferred embodiment, in step (1), the calcination temperature is 300-450° C. (eg, 350-450° C., 350-420° C.), and the calcination time is 3-6 h (eg, 4-6 h, 3-5 h).

[0058] In a preferred embodiment, in step (2), the mass volume ratio of the SnCl4 to the acetone in g / mL is 1:(50-500), preferably 1:(50-400), more preferably 1:(70-400), for example, 1:(70-300), 1:(70-250), 1:(70-220), 1:(70-150), 1:(70-110), or 1:(100-400).

[0059] In a preferred embodiment, in step (2), the stirring time is 2-10 h, for example, 2-8 h, 5-10 h, or 5-8 h.

[0060] In a preferred embodiment, in step (2), the drying temperature is 80-120°C, for example, 90-120°C, 80-100°C, 90-100°C, and the drying time is 5-12h, for example, 6-12h, 8-10h, 9-10h.

[0061] In a preferred embodiment, in step (2), the calcination temperature is 400-550°C, for example, 400-525°C, 400-500°C, 400-475°C, and the calcination time is 2-8h, for example, 2-5h, 2-6h, 2-7h.

[0062] In a preferred embodiment, in step (2), the mass content of Sn in the Sn-modified non-acidic Y molecular sieve is 0.1%-1%, such as 0.10%-0.70%, 0.18%-0.60%, or 0.18%-0.38%.

[0063] In a preferred embodiment, in step (3), the Pt loading method is selected from one or more of atomic layer deposition, chemical vapor deposition, and impregnation, preferably atomic layer deposition.

[0064] In a preferred embodiment, in step (3), the Pt source is selected from one or more of Pt(NH3)4Cl2, (trimethyl)methylcyclopentadienylplatinum, or their aqueous solutions.

[0065] In a preferred embodiment, in step (3), the Pt loading method is an impregnation method, which includes impregnating the Sn-modified non-acidic Y molecular sieve prepared in step (2) into a Pt source, and then stirring, drying and calcining to carry out Pt loading.

[0066] In a further preferred embodiment, the impregnation method satisfies one or more of the following:

[0067] The Pt source is an aqueous solution of Pt(NH3)4Cl2, wherein the mass volume ratio of Pt(NH3)4Cl2 to water in g / mL is 1:(250-300) (e.g., 1:(250-290));

[0068] The mass ratio of the Pt(NH3)4Cl2 to the Sn-modified non-acidic Y molecular sieve is 1:(250-300) (e.g., 1:(250-290));

[0069] The stirring is performed at room temperature for 6-8 hours (e.g., 7-8 hours);

[0070] The drying is carried out at 110-120° C. (e.g., 115-120° C.) for 6-8 hours (e.g., 7-8 hours);

[0071] The calcination is performed at 340-350° C. (eg, 345-350° C.) for 1.5-3 h (eg, 2-3 h).

[0072] In a preferred embodiment, in step (3), the Pt loading method is atomic layer deposition, which includes grinding the Sn-modified non-acidic Y molecular sieve prepared in step (2) and dispersing it in ethanol to obtain an ethanol dispersion, applying the ethanol dispersion on the surface of a quartz plate, and transferring it to an atomic layer deposition (ALD) chamber after drying, and then sequentially introducing a Pt source and O3 into the ALD chamber to perform Pt loading.

[0073] In a further preferred embodiment, the atomic layer deposition method satisfies one or more of the following:

[0074] The mass volume ratio of the Sn-modified non-acidic Y molecular sieve to the ethanol in g / mL is 1:(40-50);

[0075] The volume of the ethanol is 100-150 mL;

[0076] The reaction temperature in the ALD chamber is 200-250°C;

[0077] The Pt source is (trimethyl)methylcyclopentadienylplatinum;

[0078] The Pt source and O3 were introduced into the ALD chamber using N2 as a carrier gas at a carrier gas flow rate of 100-150 sccm;

[0079] The pulse time, diffusion time and purge time of the Pt source are 0.5-1s, 60-70s and 90-100s respectively;

[0080] The pulse time, diffusion time and purge time of O3 are 1-2s, 90-100s and 120-130s respectively.

[0081] In a preferred embodiment, in step (3), the Pt loading method is chemical vapor deposition, which includes vacuum drying the Sn-modified non-acidic Y molecular sieve prepared in step (2) and placing it in a chemical vapor deposition (CVD) reactor, and then sequentially introducing a Pt source and O2 into the CVD reactor to carry out Pt loading.

[0082] In a further preferred embodiment, the chemical vapor deposition method satisfies one or more of the following:

[0083] The vacuum drying is carried out at 350-360° C. for 8-9 hours;

[0084] The Pt source is introduced into a CVD reactor using N2 as a carrier gas;

[0085] The Pt source is (trimethyl)methylcyclopentadienylplatinum;

[0086] The temperature of the Pt source is 65-70°C;

[0087] The Pt source is introduced for 2-5 minutes;

[0088] The O2 introduction time is 10-15min;

[0089] The flow rate of O2 is 60-70 mL / min;

[0090] The flow rate of N2 is 60-70 mL / min.

[0091] In a preferred embodiment, in step (3), the Pt-loaded molecular sieve is mixed with quartz sand and then placed in a fixed bed reaction tube for the reduction treatment.

[0092] In a preferred embodiment, in step (3), the mass ratio of the Pt-loaded molecular sieve to the quartz sand is 1:(25-30).

[0093] In a preferred embodiment, in step (3), the temperature of the reduction treatment is 300-550°C, preferably 350-550°C, for example, 350-500°C, 350-450°C, 350-420°C, and the time of the reduction treatment is 1-5h, for example, 2-5h, 3-5h, 4-5h. Preferably, the reduction treatment is carried out in a H2 gas flow of 40-50mL / min.

[0094] In some embodiments, the present invention provides a Pt-based catalyst obtained by the preparation method described above.

[0095] In some embodiments, the present invention provides the use of the above-described Pt-based catalyst in the catalytic reforming of naphtha. Preferably, the use is for the catalytic reforming of naphtha into C8 aromatics; preferably, the use is for the selective catalytic reforming of naphtha into C8 aromatics with a C8 aromatic content of 55% or more (preferably 60% or more, more preferably 70% or more, further preferably 80% or more, and even up to 90% or more, for example 93% or more).

[0096] In some embodiments, the present invention provides a method for catalytic reforming of naphtha, comprising catalytically reforming naphtha using the Pt-based catalyst described above.

[0097] In a preferred embodiment, the naphtha is C6-C 10 Alkanes (such as C6-C 10 One or more of straight-chain alkanes), preferably C8 alkanes (such as C8 straight-chain alkanes), the target product of the catalytic reforming of naphtha is C8 aromatics, preferably ethylbenzene and o-xylene.

[0098] In a preferred embodiment, in the naphtha catalytic reforming reaction product, the selectivity of C8 aromatics is above 55%, preferably above 60%, more preferably above 70%, further preferably above 80%, and even up to above 90%, for example above 93%.

[0099] In a preferred embodiment, among the C8 aromatics in the naphtha catalytic reforming reaction product, the proportion of ethylbenzene and o-xylene is more than 95%, preferably more than 96%, more preferably more than 97%, and even more than 98%.

[0100] In a preferred embodiment, the reaction conditions of the naphtha catalytic reforming (also known as "aromatization of alkanes to aromatics") are: reaction pressure of 0.1-0.5 MPa (e.g., 0.1-0.3 MPa), reaction temperature of 350-550°C (e.g., 450-550°C), mass space velocity of 0.3-1.5 h -1, the molar ratio of H2 to naphtha (preferably straight-chain alkane) is: (4-10):1, for example (4-6):1, (4-8):1, (5-10):1.

[0101] Example

[0102] The method provided by the present invention is described in detail below through examples, but the present invention is not limited thereto.

[0103] Example 1

[0104] 1. Place 0.66g of NaOH in 50mL of anhydrous methanol and stir at room temperature until the NaOH is completely dissolved to obtain a sodium methoxide solution. Place 2g of Y molecular sieve (Tianjin Nanhua Catalyst Co., Ltd.) with a silicon-aluminum ratio of 5 in the sodium methoxide solution and stir at room temperature for 20 minutes. Centrifuge to obtain a centrifuged solid and a supernatant. Wash the centrifuged solid with a washing agent. Repeat the centrifugation and washing steps until the supernatant is neutral. Each centrifugation is performed at a speed of 10,000 rpm for 6 minutes, using 120g of anhydrous methanol as the washing agent. The washed solid is then dried at 90°C for 12 hours and calcined at 300°C for 6 hours to obtain an alkali metal-modified, non-acidic NaY molecular sieve.

[0105] 2. Prepare a mixture of SnCl₄ and acetone by dissolving 0.0201 g of SnCl₄ in 1.5 mL of anhydrous acetone. Add 1.5 g of the alkali metal-modified, non-acidic NaY molecular sieve prepared above to the mixture and stir at room temperature for 5 hours. Dry the resulting mixture at 90°C for 12 hours and then calcine at 400°C for 8 hours to obtain a Sn-modified, non-acidic NaY molecular sieve. ICP analysis reveals a Sn content of 0.60%.

[0106] 3. Pt loading was performed using the following impregnation method: 0.0069 g of Pt(NH3)4Cl2 was placed in 2 mL of deionized water to prepare a Pt(NH3)4Cl2 aqueous solution. 2 g of the Sn-modified, non-acidic NaY molecular sieve prepared above was placed in the Pt(NH3)4Cl2 aqueous solution and stirred at room temperature for 8 h. The mixture obtained after stirring was dried at 120°C for 8 h and then calcined at 350°C for 3 h. 0.6 g of the calcined product was mixed with 15 g of quartz sand and placed in a fixed-bed reaction tube. The mixture was reduced at 550°C for 1 h in a 50 mL / min H2 gas flow to obtain a Pt-based catalyst.

[0107] Example 2

[0108] 1. Take 0.24g of Mg(OH)2 and place it in 50mL of anhydrous ethanol. Stir at room temperature until the Mg(OH)2 is completely dissolved to obtain a magnesium ethoxide solution. 2g of Y molecular sieve (Tianjin Nanhua Catalyst Co., Ltd.) with a silicon-aluminum ratio of 20 is placed in the above-mentioned magnesium ethoxide solution, stirred at room temperature for 60 minutes, and centrifuged to obtain a centrifuged solid and a supernatant. The centrifuged solid is washed with a detergent. The centrifugation and washing operations are repeated until the supernatant is neutral. Each centrifugation speed is 10000rpm and the centrifugation time is 6 minutes. The amount of anhydrous ethanol used for each centrifugation is 120g. The washed solid is then dried at 105°C for 10 hours and calcined at 350°C for 5 hours to obtain an alkali metal-modified non-acidic MgY molecular sieve.

[0109] 2. Prepare a mixture of SnCl₄ and acetone by dissolving 0.0134 g of SnCl₄ in 1.5 mL of anhydrous acetone. Add 1.5 g of the alkali metal-modified, non-acidic MgY molecular sieve prepared above to the mixture and stir at room temperature for 8 hours. Dry the resulting mixture at 100°C for 9 hours and then calcine it at 475°C for 5 hours to obtain the Sn-modified, non-acidic MgY molecular sieve. ICP analysis reveals a Sn content of 0.38%.

[0110] 3. Pt loading was performed using the following chemical vapor deposition method: 2.0 g of the obtained Sn-modified non-acidic MgY molecular sieve was placed in a vacuum drying oven and vacuum dried at 350 ° C for 8 h. The vacuum-dried molecular sieve was then placed in a CVD (Chemical Vapor Deposition, CVD, i.e., chemical vapor deposition) reactor, maintaining the (trimethyl) methylcyclopentadienyl platinum (i.e., Pt source) temperature at 65 ° C. The Pt source was brought into the CVD reactor using N2 (60 mL / min) as a carrier gas. After maintaining for 2 min, O2 (60 mL / min) was introduced for 10 min. Subsequently, 0.6 g of the obtained intermediate product was mixed with 15 g of quartz sand and loaded into a fixed bed reaction tube. The mixture was reduced at 420 ° C for 3 h in a 50 mL / min H2 gas flow to obtain a Pt-based catalyst.

[0111] Example 3

[0112] 1. 0.30 g of Ba(OH)2 was placed in 50 mL of anhydrous isopropanol and stirred at room temperature until the Ba(OH)2 was completely dissolved to obtain a barium isopropoxide solution. 2 g of Y molecular sieve (Tianjin Nanhua Catalyst Co., Ltd.) with a silicon-aluminum ratio of 50 was placed in the barium isopropoxide solution and stirred at room temperature for 100 minutes. The mixture was centrifuged to obtain a solid and a supernatant. The solid was washed with a detergent. The centrifugation and washing steps were repeated until the supernatant was neutral. Each centrifugation was performed at 10,000 rpm for 6 minutes, using 120 g of isopropanol as the washing agent. The washed solid was then dried at 120°C for 6 hours and calcined at 450°C for 3 hours to obtain an alkali metal-modified, non-acidic BaY molecular sieve.

[0113] 2. Prepare a SnCl4 / acetone mixture by dissolving 0.0038g of SnCl4 in 1.5mL of anhydrous acetone. Add 1.5g of the alkali metal-modified, non-acidic BaY molecular sieve prepared above to this mixture and stir at room temperature for 10 hours. Dry the resulting mixture at 120°C for 6 hours and then calcine at 550°C for 2 hours to obtain the Sn-modified, non-acidic BaY molecular sieve. ICP analysis reveals a Sn content of 0.10%.

[0114] 3. Pt loading was performed using the following atomic layer deposition technique: 2.5 g of the Sn-modified non-acidic BaY molecular sieve prepared above was ground and dispersed in 100 mL of ethanol to obtain an ethanol dispersion, which was then evenly coated on the surface of a quartz wafer and transferred to an ALD (Atomic Layer Deposition, ALD, atomic layer deposition) chamber after drying at room temperature. The reaction temperature of the ALD chamber was 250 ° C, and N2 with a flow rate of 150 sccm was used as a carrier gas. The first reactant (trimethyl) methylcyclopentadiene platinum (i.e., Pt source) and the second reactant O3 were sequentially introduced for reaction. The pulse, diffusion, and purge times of the Pt source were set to 0.5 s, 60 s, and 90 s, respectively, and the pulse, diffusion, and purge times of the second reactant O3 were set to 1 s, 90 s, and 120 s, respectively. The number of Pt ALD deposition cycles was 1, thereby loading Pt on the surface of the Sn-modified non-acidic molecular sieve. 0.6 g of the catalyst prepared above was mixed with 15 g of quartz sand and placed in a fixed-bed reaction tube. The mixture was reduced at 350° C. for 5 h in a 50 mL / min H 2 gas flow to obtain a Pt-based catalyst.

[0115] Example 4

[0116] 1. Take 0.17g KOH and place it in 50mL anhydrous methanol, stir at room temperature until KOH is completely dissolved to obtain potassium methoxide solution. Place 2g Y molecular sieve (Tianjin Nanhua Catalyst Co., Ltd.) with a silicon-aluminum ratio of 30 in the above potassium methoxide solution, stir at room temperature for 10min, and centrifuge to obtain a centrifuged solid and a supernatant. Wash the centrifuged solid with a washing agent, and repeat the centrifugation and washing operations until the supernatant obtained is neutral. The amount of anhydrous methanol used for each centrifugal washing agent is 120g. Then, the washed solid is dried at 80°C for 8h and calcined at 420°C for 4h to obtain an alkali metal-modified non-acidic KY molecular sieve.

[0117] 2. Prepare a mixture of SnCl4 and acetone by placing 0.0067g of SnCl4 in 1.5mL of anhydrous acetone. Add 1.5g of the alkali metal-modified, non-acidic KY molecular sieve prepared above to the mixture and stir at room temperature for 2h. Dry the mixture at 80°C for 8h and then calcine at 550°C for 5h to obtain Sn-modified non-acidic KY molecular sieve. ICP testing shows a Sn content of 0.18%.

[0118] 3. The following atomic layer deposition technology is used for Pt loading: 2.5g of the above-prepared Sn-modified non-acidic KY molecular sieve is ground and dispersed in 100mL of ethanol to obtain an ethanol dispersion, which is then evenly coated on the surface of a quartz plate and transferred to an ALD chamber after drying at room temperature. The reaction temperature of the ALD chamber is 250°C, and N2 with a flow rate of 150sccm is used as a carrier gas. The first reactant (trimethyl) methylcyclopentadiene platinum (i.e., Pt source) and the second reactant O3 are sequentially introduced for reaction, wherein the pulse, diffusion, and purge times of the Pt source are set to 0.5s, 60s, and 90s, respectively, and the pulse, diffusion, and purge times of the second reactant O3 are set to 1s, 90s, and 120s, respectively. The number of Pt ALD deposition cycles is 1, thereby loading Pt on the surface of the Sn-modified non-acidic molecular sieve. 0.6 g of the catalyst prepared above was mixed with 15 g of quartz sand and placed in a fixed-bed reaction tube. The mixture was reduced at 500° C. for 2 h in a 50 mL / min H 2 gas flow to obtain a Pt-based catalyst.

[0119] Comparative Example

[0120] 1. Prepare a mixture of SnCl4 and acetone by placing 0.0067g of SnCl4 in 1.5mL of anhydrous acetone. Add 1.5g of Y molecular sieve (Tianjin Nanhua Catalyst Co., Ltd.) with a silicon-aluminum ratio of 30 to the mixture and stir at room temperature for 2h. Dry the resulting mixture at 80°C for 8h and then calcine it at 550°C for 5h to obtain Sn-modified Y molecular sieve. ICP analysis revealed a Sn content of 0.18%.

[0121] 2. The following atomic layer deposition technology is used for Pt loading: 2.5g of the Sn-modified Y molecular sieve prepared above is ground and dispersed in 100mL of ethanol to obtain an ethanol dispersion, which is then evenly coated on the surface of a quartz plate and transferred to an ALD chamber after drying at room temperature. The reaction temperature of the ALD chamber is 250°C, and N2 with a flow rate of 150sccm is used as a carrier gas. The first reactant (trimethyl) methylcyclopentadiene platinum (i.e., Pt source) and the second reactant O3 are sequentially introduced for reaction, wherein the pulse, diffusion, and purge times of the Pt source are set to 0.5s, 60s, and 90s, respectively, and the pulse, diffusion, and purge times of the second reactant O3 are set to 1s, 90s, and 120s, respectively. The number of Pt ALD deposition cycles is 1, thereby loading Pt on the surface of the Sn-modified Y molecular sieve. 0.6 g of the catalyst prepared above was mixed with 15 g of quartz sand and placed in a fixed-bed reaction tube. The mixture was reduced at 500° C. for 2 h in a 50 mL / min H 2 gas flow to obtain a Pt-based catalyst.

[0122] Experimental Example: Performance Measurement of Alkane Aromatization Reaction (i.e., Naphtha Catalytic Reforming)

[0123] Taking n-octane as the experimental model reactant for the aromatization of alkanes, the aromatization performance of the catalysts prepared by Examples 1 to 4 and the comparative examples was evaluated. The Pt-based catalysts prepared by Examples 1 to 4 and the comparative examples were placed in a fixed bed reaction tube (the reaction temperature was reduced to 450°C, the reaction pressure was adjusted to 0.1MPa, and the H2 gas flow rate was adjusted to 8mL / min). Subsequently, the liquid feed pump was started, and the n-octane was fed into the reaction tube at a flow rate of 0.8mL / h. The online reaction began and lasted for 10 hours. The obtained product was kept warm in a 200°C heating belt and then entered the online gas chromatograph for component analysis. The analysis results are shown in Table 1. The stability results of the catalyst in Example 4 in this reaction are shown in Table 1. Figure 6 .

[0124] Table 1 Evaluation results of catalytic performance of catalysts in Examples 1 to 4 and Comparative Examples

[0125]

[0126] "Conversion rate" refers to the proportion of alkanes (e.g., n-octane) converted in an alkane aromatization reaction;

[0127] “Aromatic selectivity” refers to the proportion of aromatic compounds in all reaction products of alkane aromatization reaction;

[0128] "Ethylbenzene selectivity" refers to the proportion of ethylbenzene in all reaction products of alkane aromatization reaction; "o-xylene selectivity" refers to the proportion of o-xylene in all reaction products of alkane aromatization reaction; "(p-xylene + m-xylene) selectivity" refers to the proportion of p-xylene and m-xylene in all reaction products of alkane aromatization reaction;

[0129] "C8 aromatics selectivity", "C8 olefins selectivity", "C1-C4 selectivity" and "C5-C8 selectivity" respectively refer to the proportions of C8 aromatics (such as xylene, ethylbenzene, etc.), C8 olefins (such as 1-octene, 2-octene, etc.), C1-C4 hydrocarbons (such as methane, ethane, propane, butane, etc.), and C5-C8 hydrocarbons (such as pentane, hexane, heptane, octane, etc.) in all reaction products of alkane aromatization reaction.

[0130] According to the results in Table 1, the Pt-based catalyst of the present invention exhibits excellent aromatization performance in the aromatization of medium- and long-chain alkanes, and can achieve a C8 aromatics selectivity of more than 56.8% and even up to 93.5%. Moreover, the obtained C8 aromatics are mainly ethylbenzene and o-xylene, and the total proportion of the two in the C8 aromatics can reach more than 95%, and the ratio is about 1:1, with excellent C8 aromatics distribution. At the same time, Figure 6 As shown in the results, the Pt-based catalyst of the present invention has excellent stability and can operate stably for more than 12 hours.

[0131] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing a naphtha catalytic reforming catalyst, the method comprising the following steps: (1) Modifying the Y molecular sieve with an alkali metal alcohol solution or an alkaline earth metal alcohol solution to obtain an alkali metal or alkaline earth metal modified non-acidic Y molecular sieve; (2) placing the molecular sieve prepared in step (1) in a mixture of SnCl4 and acetone, stirring, drying and calcining to obtain a Sn-modified non-acidic Y molecular sieve; (3) After the Sn-modified non-acidic Y molecular sieve prepared in step (2) is loaded with Pt using a Pt source, a reduction treatment is performed to obtain a Pt-based catalyst.

2. The preparation method according to claim 1, wherein in step (1), the modification with an alkali metal alcohol solution or an alkaline earth metal alcohol solution comprises: The Y molecular sieve and the alkali metal alcohol solution or alkaline earth metal alcohol solution are stirred at room temperature, the stirred mixed solution is centrifuged to obtain a centrifuged solid and a supernatant, the centrifuged solid is washed with a washing agent, the centrifugation and washing operations are repeated until the obtained supernatant is neutral, and the washed solid is dried and calcined to obtain an alkali metal or alkaline earth metal modified non-acidic Y molecular sieve.

3. The preparation method according to claim 1 or 2, wherein in step (1), the silicon-aluminum ratio of the Y molecular sieve is (3-60):1; Preferably, the alkali metal alcohol solution is a mixture of an alkali metal hydroxide and a C1-C4 alcohol, and the alkaline earth metal alcohol solution is a mixture of an alkaline earth metal hydroxide and a C1-C4 alcohol; Preferably, the alkali metal hydroxide or alkaline earth metal hydroxide includes one or more of potassium hydroxide, sodium hydroxide, magnesium hydroxide, and barium hydroxide; Preferably, the C1-C4 alcohol includes one or more of anhydrous methanol, anhydrous ethanol, and anhydrous isopropanol; Preferably, the mass ratio of the alkali metal hydroxide or alkaline earth metal hydroxide to the Y molecular sieve is 1:(3-50); Preferably, the mass volume ratio of the alkali metal hydroxide or alkaline earth metal hydroxide to the C1-C4 alcohol in g / mL is 1:(50-400).

4. The preparation method according to claim 2 or 3, wherein in step (1), the stirring time is 10-100 min; Preferably, for each centrifugation, the centrifugal speed is 10000-11000 rpm and the centrifugation time is 6-7 min; Preferably, the washing agent is one or more of anhydrous methanol, anhydrous ethanol, and anhydrous isopropanol; Preferably, the drying temperature is 80-120°C and the drying time is 5-12 hours; Preferably, the calcination temperature is 300-450° C., and the calcination time is 3-6 hours.

5. The preparation method according to any one of claims 1 to 4, wherein In step (2), the mass volume ratio of the SnCl4 to the acetone in g / mL is 1:(50-500); Preferably, the stirring time is 2-10h; Preferably, the drying temperature is 80-120°C and the drying time is 5-12 hours; Preferably, the calcination temperature is 400-550°C and the calcination time is 2-8h; Preferably, the mass content of Sn in the Sn-modified non-acidic Y molecular sieve is 0.1%-1%.

6. The preparation method according to any one of claims 1 to 5, wherein In step (3), the Pt source is selected from one or more of Pt(NH3)4Cl2, (trimethyl)methylcyclopentadienylplatinum, or their aqueous solutions; Preferably, the Pt loading method is selected from atomic layer deposition, chemical vapor deposition, or impregnation; Preferably, the Pt loading method is an impregnation method, which comprises impregnating the Sn-modified non-acidic Y molecular sieve prepared in step (2) into a Pt source, and then stirring, drying and calcining to load Pt; Preferably, the Pt loading method is an atomic layer deposition method, which includes grinding the Sn-modified non-acidic Y molecular sieve prepared in step (2) and dispersing it in ethanol to obtain an ethanol dispersion, applying the ethanol dispersion on the surface of a quartz plate, drying it and transferring it to an atomic layer deposition chamber, and then sequentially introducing a Pt source and O3 into the atomic layer deposition chamber to perform Pt loading; Preferably, the Pt loading method is chemical vapor deposition, which includes vacuum drying the Sn-modified non-acidic Y molecular sieve prepared in step (2) and placing it in a chemical vapor deposition reactor, and then sequentially introducing a Pt source and O2 into the chemical vapor deposition reactor to perform Pt loading.

7. The preparation method according to any one of claims 1 to 6, wherein In step (3), the molecular sieve loaded with Pt is mixed with quartz sand and then placed in a fixed bed reaction tube for the reduction treatment; Preferably, the mass ratio of the Pt-loaded molecular sieve to the quartz sand is 1:(25-30); Preferably, the temperature of the reduction treatment is 300-550°C; Preferably, the reduction treatment time is 1-5h; Preferably, the reduction treatment is carried out in a H2 gas flow of 40-50 mL / min.

8. A Pt-based catalyst, obtained by the preparation method according to any one of claims 1 to 7.

9. Use of the Pt-based catalyst obtained by the preparation method according to any one of claims 1 to 7 or the Pt-based catalyst according to claim 8 in catalytic reforming of naphtha.

10. A method for catalytic reforming of naphtha, comprising catalytically reforming naphtha using the Pt-based catalyst obtained by the preparation method according to any one of claims 1 to 7 or the Pt-based catalyst according to claim 8; Preferably, the naphtha is C6-C 10 Alkanes; Preferably, the target product of the naphtha catalytic reforming is C8 aromatics; Preferably, the reaction conditions of the catalytic reforming are: reaction pressure of 0.1-0.5 MPa, reaction temperature of 350-550°C, mass space velocity of 0.3-1.5 h -1 , the molar ratio of H2 to naphtha is (5-10):1.

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