Liquid-phase non-hydroxylene isomerization catalyst, preparation method thereof and liquid-phase non-hydroxylene isomerization method

Abstract

The invention relates to a liquid-phase non-hydroxylene isomerization catalyst, a preparation method thereof and a liquid-phase non-hydroxylene isomerization method. The liquid-phase non-hydroxylene isomerization catalyst comprises 10-80% of an H-type molecular sieve and 20-90% of a binder. The H-type molecular sieve comprises 5-90% of a ZSM-5 molecular sieve, 5-90% of a Beta molecular sieve and 5-90% of a ZSM-48 molecular sieve. When the xylene isomerization catalyst disclosed by the invention is used for catalyzing liquid-phase non-hydroxylene isomerization reaction, high p-xylene isomerization activity and xylene yield are shown, and very good p-xylene selectivity is achieved; the preparation process of the catalyst does not need to load noble metal, and does not need the steps of activation, reduction and the like, thereby simplifying the preparation flow and reducing the cost; compared with a gas-phase xylene isomerization reaction, the liquid-phase non-hydroxylene isomerization method disclosed by the invention is lower in reaction temperature, greatly reduced in energy consumption and more environment-friendly.

Description

Technical Field

[0001] This invention relates to the field of xylene isomerization technology, specifically to a liquid-phase non-hydrogenated xylene isomerization catalyst and its preparation method, and a liquid-phase non-hydrogenated xylene isomerization method. Background Technology

[0002] Para-xylene (PX) is an important chemical raw material, mainly used in the production of terephthalic acid, and further in the production of ethylene glycol terephthalate, butylene terephthalate, and other products. In addition, it can be used in coatings, dyes, pesticides, and pharmaceuticals. With the continuous development of these industries in my country, the demand for PX has grown rapidly. To meet market demand, the construction scale of aromatic hydrocarbon complexes, mainly producing PX, is constantly expanding. These complexes consist of C8 aromatic hydrocarbon isomerization, xylene distillation, and adsorption or crystallization separation technologies. Among them, the xylene isomerization unit technology for increasing PX production is a key means to convert ethylbenzene, m-xylene, and o-xylene into PX. Typically, aromatic hydrocarbon complexes use traditional crystallization or molecular sieve adsorption methods to separate pure PX. The remaining C8 aromatic hydrocarbons, after being processed by a heptane removal tower and a xylene removal tower to remove small amounts of light non-aromatic hydrocarbons, benzene, toluene, and C9+ heavy aromatic hydrocarbons, can be used as isomerization feedstock. After passing through the xylene isomerization unit, the three xylene isomers in C8 aromatics can reach or approach thermodynamic equilibrium composition, namely 52-54% by mass of m-xylene, 23-24% by mass of p-xylene, and 23-24% by mass of o-xylene, which are then recycled back to the separation unit for purification of p-xylene. However, ethylbenzene in the C8 aromatic feed requires higher isomerization temperatures and conditions such as hydrogenation to be converted into xylene or deethylated to produce benzene. In recent years, with the continuous advancement of combined processes, various methods have been developed to ensure that the mixed C8 aromatics in the isomerization feed are essentially free of ethylbenzene. This allows for the catalytic isomerization of o-xylene and m-xylene at lower temperatures and in the liquid phase under conditions of non-hydrogenation or relying solely on dissolved hydrogen to maintain catalyst stability, thereby significantly reducing energy and material consumption in PX production.

[0003] Taking into account the process design and power consumption of the device, selecting non-hydrogen-contaminated liquid phase conditions for the isomerization reaction unit is a technical solution with unique advantages.

[0004] Patent CN116425171A discloses a method for preparing a mesoporous cascade structure ZSM-48 molecular sieve. The method involves uniformly mixing Beta seed crystals, a silicon source, an aluminum source, an alkali source, an organic template agent, a mesoporous building agent, and water to form a gel. After hydrothermal crystallization, a low Si / Al ratio ZSM-48 molecular sieve with a SiO2 / Al2O3 molar ratio ranging from 40 to 100 is obtained. The crystals have a length of 2–5 μm and a diameter of 0.5–2.0 μm, exhibiting a needle-like structure. By controlling the type and proportion of the added mesoporous building agent, the number of mesopores can be adjusted, achieving in-situ synthesis of the mesoporous cascade structure ZSM-48 molecular sieve. The method demonstrates that the mesoporous cascade structure ZSM-48 possesses excellent hydroisomerization catalytic performance.

[0005] US9809509 uses small-crystal ZSM-23 molecular sieves with a SiO2 / Al2O3 molar ratio between 15 and 75 as the acidic component of the catalyst for a liquid-phase isomerization reaction at 260℃ for 5.2 hours. -1 At a space velocity of 3.1 MPa, the PX / X ratio (PX represents the p-xylene content in the product, and X represents the total xylene content in the product) can be greater than the gas phase equilibrium value of 24 by mass.

[0006] Patent US20170297977A1 ​​describes a liquid-phase non-hydrogen-dependent xylene isomerization catalyst that uses UZM-54 molecular sieve, preferably with a 70% molecular sieve content, and alumina as the binder, eliminating the need for metal loading. Under non-hydrogen-dependent conditions, the xylene isomerization reaction can reach thermodynamic equilibrium.

[0007] The catalyst prepared using Ga-MFI molecular sieves in US7371913 can perform alkyl aromatic hydrocarbon isomerization in a completely hydrogen-free state, while retaining higher levels of ethylbenzene and C8 cycloalkanes in the feedstock when the isomerization achieves good performance.

[0008] US20110263918 A1 describes a xylene isomerization process using HZSM-5 or MCM-49 as the acidic catalyst. Under conditions of below 295°C and pressure ensuring the reactants are in a liquid state, a xylene fraction with a near-equilibrium composition can be obtained. This process can operate continuously when the feed only requires ppm-level dissolved hydrogen. It can also be recycled with non-hydrogen-dependent feeds, but the catalyst needs periodic regeneration with low-ppm-level hydrogen.

[0009] The literature "A Study on Xylene Liquid-Phase Isomerization Catalysts" (Petrochemical Technology, Vol. 7, No. 3, 1978) investigated the performance of xylene liquid-phase isomerization reaction on the ZSM-5 catalyst, synthesized from water glass, aluminum sulfate, sulfuric acid, and ethylamine. Experimental results showed that the ZSM-5 zeolite catalyst exhibits high activity and selectivity for xylene liquid-phase isomerization and is suitable for mixed xylene feedstocks containing ethylbenzene.

[0010] In the aforementioned patents and literature, the xylene liquid-phase isomerization reaction exhibits high activity, but requires trace amounts of dissolved hydrogen to maintain catalyst stability. Furthermore, achieving high activity typically implies a decrease in reaction selectivity.

[0011] Finding a xylene isomerization catalyst that exhibits high p-xylene isomerization activity and xylene yield in the catalytic liquid-phase non-hydrogenated xylene isomerization reaction, while simplifying the catalyst preparation process and reducing costs, is a pressing technical problem that needs to be solved. Summary of the Invention

[0012] To address the above problems, this invention provides a liquid-phase non-hydroxylene isomerization catalyst and its preparation method, as well as a liquid-phase non-hydroxylene isomerization method.

[0013] On one hand, the present invention provides a liquid-phase non-hydrogenated xylene isomerization catalyst, comprising 10-80% H-type molecular sieve and 20-90% binder, based on the total mass of the liquid-phase non-hydrogenated xylene isomerization catalyst;

[0014] The H-type molecular sieve comprises the following components in the following proportions based on the total mass of the H-type molecular sieve:

[0015] ZSM-5 molecular sieve 5-90%

[0016] Beta molecular sieve 5-90%

[0017] ZSM-48 molecular sieve: 5-90%.

[0018] On the other hand, the present invention provides a method for preparing the above-mentioned liquid-phase non-hydroxylene isomerization catalyst, comprising the following steps:

[0019] (1) Provide alkali metal ion type ZSM-5 molecular sieve;

[0020] (2) Provide alkali metal ion type Beta molecular sieves;

[0021] (3) Provide alkali metal ion type ZSM-48 molecular sieve;

[0022] (4) The alkali metal ion type ZSM-5 molecular sieve, the alkali metal ion type Beta molecular sieve and the alkali metal ion type ZSM-48 molecular sieve are mixed with a binder and then added to an acid solution for kneading, molding and first calcination. Then, they are contacted with an ammonium salt solution for ion exchange and second calcination to obtain the liquid phase non-hydroxylene isomerization catalyst.

[0023] In another aspect, the present invention also provides a liquid-phase non-hydrogenated xylene isomerization method, comprising contacting a raw material containing alkyl aromatics with a catalyst under a reaction pressure that maintains a liquid state to carry out a liquid-phase non-hydrogenated xylene isomerization reaction; wherein the catalyst is the above-mentioned liquid-phase non-hydrogenated xylene isomerization catalyst, or is prepared by the above method;

[0024] Preferably, the liquid-phase non-hydroxylene isomerization reaction is carried out at 240–310 °C and a weight hourly space velocity of 1–10 h⁻¹. -1 The following will proceed.

[0025] Beneficial effects:

[0026] The xylene isomerization catalyst of this invention exhibits high p-xylene isomerization activity and xylene yield in the catalytic liquid-phase non-hydrogenated xylene isomerization reaction, with excellent p-xylene selectivity. Furthermore, the catalyst preparation process does not require loading of precious metals, nor does it require activation or reduction steps, simplifying the preparation process and reducing costs. Compared with gas-phase xylene isomerization, the liquid-phase non-hydrogenated xylene isomerization method of this invention has a lower reaction temperature, significantly reduced energy consumption, and is more environmentally friendly. Attached Figure Description

[0027] Figure 1 The XRD diffraction patterns of the ZSM-5 molecular sieves prepared in Examples 1-3 of this invention are shown below.

[0028] Figure 2 The XRD diffraction patterns of the Beta molecular sieves prepared in Examples 1-3 of this invention are shown below.

[0029] Figure 3 The XRD diffraction patterns of the ZSM-48 molecular sieves prepared in Examples 1 to 3 of this invention are shown below.

[0030] Figure 4 The images show the SEM characterization of the ZSM-5 molecular sieves prepared in Examples 1-3 of this invention.

[0031] Figure 5 These are SEM characterization images of the Beta molecular sieves prepared in Examples 1-3 of this invention;

[0032] Figure 6 The images show the SEM characterization of the ZSM-48 molecular sieves prepared in Examples 1-3 of this invention. Detailed Implementation

[0033] 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.

[0034] 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.

[0035] 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.

[0036] On one hand, the present invention provides a liquid-phase non-hydrogenated xylene isomerization catalyst, comprising 10-80% H-type molecular sieve and 20-90% binder, based on the total mass of the liquid-phase non-hydrogenated xylene isomerization catalyst;

[0037] The H-type molecular sieve comprises the following components in the following proportions based on the total mass of the H-type molecular sieve:

[0038] ZSM-5 molecular sieve 5-90%

[0039] Beta molecular sieve 5-90%

[0040] ZSM-48 molecular sieve: 5-90%.

[0041] In the liquid-phase non-hydrogenated xylene isomerization catalyst of the present invention, the above-mentioned three H-type molecular sieves are combined to form the active component. The three H-type molecular sieves synergistically enhance the effect, the catalyst does not require loading of noble metals, and has high p-xylene isomerization activity and xylene yield. In the liquid-phase non-hydrogenated xylene isomerization catalyst, the sum of the proportion of H-type molecular sieves and the proportion of binder is 100%. Specifically, the proportion of H-type molecular sieves can be 20%, 30%, 40%, 50%, 60%, 70%, etc., and the proportion of binder can be 30%, 40%, 50%, 60%, 70%, 80%, etc. In the H-type molecular sieves, the sum of the proportions of ZSM-5 molecular sieve, Beta molecular sieve, and ZSM-48 molecular sieve is 100%. Specifically, the proportion of each molecular sieve can be independently 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, etc.

[0042] On the other hand, the present invention also provides a method for preparing the above-mentioned liquid-phase non-hydroxylene isomerization catalyst, comprising the following steps:

[0043] (1) Provide alkali metal ion type ZSM-5 molecular sieve;

[0044] (2) Provide alkali metal ion type Beta molecular sieves;

[0045] (3) Provide alkali metal ion type ZSM-48 molecular sieve;

[0046] (4) The alkali metal ion type ZSM-5 molecular sieve, the alkali metal ion type Beta molecular sieve and the alkali metal ion type ZSM-48 molecular sieve are mixed with a binder and then added to an acid solution for kneading, molding and first calcination. Then, they are contacted with an ammonium salt solution for ion exchange and second calcination to obtain the liquid phase non-hydroxylene isomerization catalyst.

[0047] It should be noted that the method for preparing the liquid-phase non-hydrogenated xylene isomerization catalyst of this invention does not require impregnation or loading of precious metals, nor does it require activation or reduction steps, thus simplifying the catalyst preparation process, shortening the preparation cycle, and improving the catalyst preparation efficiency. Furthermore, the prepared catalyst, when used in the liquid-phase xylene isomerization reaction, is more cost-effective than the gas-phase xylene isomerization reaction, achieving higher isomerization activity and xylene yield while at a lower reaction temperature and with less energy consumption.

[0048] In the method of the present invention, in step (4), after contact with ammonium salt solution for ion exchange, the three alkali metal ion molecular sieves are respectively converted into ammonium ion molecular sieves. Then, after the subsequent second calcination, the three ammonium ion molecular sieves are respectively converted into H-type molecular sieves.

[0049] In one embodiment of the method described above, the preparation method of the alkali metal ion-type ZSM-5 molecular sieve in step (1) includes:

[0050] The first silicon source, the first aluminum source, the first template agent, the first alkali, and water are mixed and subjected to first crystallization. The solid phase is then washed and dried to obtain the alkali metal ion-type ZSM-5 molecular sieve; and / or

[0051] The preparation method of the alkali metal ion type Beta molecular sieve in step (2) includes:

[0052] A second silicon source, a second aluminum source, a second template agent, a second alkali, and water are mixed and subjected to a second crystallization. The solid phase is then washed and dried to obtain the alkali metal ion-type Beta molecular sieve; and / or

[0053] The preparation method of the alkali metal ion type ZSM-48 molecular sieve in step (3) includes:

[0054] The third silicon source, third aluminum source, third template agent, third alkali, and water are mixed and subjected to third crystallization. The solid phase is then washed and dried to obtain the alkali metal ion-type ZSM-48 molecular sieve; and / or

[0055] Step (4) further includes a first drying between the molding and the first calcination; and / or

[0056] Step (4) also includes washing and second drying between the ion exchange and the second calcination.

[0057] It should be noted that the three types of alkali metal ion molecular sieve raw powders prepared according to the above method can be dried at 100-140℃ for 8-24 hours after thorough washing. During ion exchange in step (4), the ammonium salt solution can be ammonium chloride solution. After ion exchange, the powder can be washed several times with water. The washing solution should not contain chloride ions, and should be neutral, such as with a pH of 6-8. Then, a second drying can be carried out at 100-140℃ for 4-24 hours. The second calcination can be carried out at 520-550℃ in an air atmosphere for 2-24 hours, or in a static atmosphere without air flow, or at a volume hourly space velocity (VHSV) of 50-500 h⁻¹. -1 It takes place in a dynamic atmosphere.

[0058] The method of the present invention does not require loading of precious metals in either the molecular sieve preparation stage or the catalyst forming stage, nor does it require activation, reduction or other steps. Moreover, the catalyst finally prepared can achieve high p-xylene isomerization activity and xylene yield when used for catalytic isomerization reaction.

[0059] In another embodiment of the method described above, the molar ratio of the first silicon source (calculated as SiO2), the first aluminum source (calculated as Al2O3), the first template agent, the first alkali, and water is 1:(0.005~0.05):(0.05~1):(0.02~1):(10~60).

[0060] It should be noted that, in the preparation of alkali metal ion-type ZSM-5 molecular sieves, the molar ratio of SiO2 / Al2O3 in the crystallization raw materials for the first crystallization is 20–200:1, preferably 25–150:1, that is, the molar ratio of the first silicon source (based on SiO2) to the first aluminum source (based on Al2O3) is 20–200:1, preferably 25–150:1. The molar ratio of the first silicon source (based on SiO2) to the first template agent is preferably 1:0.06–0.9. By controlling the molar ratios of the components as described above in the preparation of alkali metal ion-type ZSM-5 molecular sieves, the performance of the prepared alkali metal ion-type ZSM-5 molecular sieve can be improved, and it can then better synergize with Beta molecular sieves and ZSM-48 molecular sieves, ultimately improving the p-xylene isomerization activity and xylene yield of the resulting catalyst.

[0061] In one embodiment of the method described above, the first template agent is selected from quaternary ammonium bases and / or quaternary ammonium salts, and has the structural formula N(R)4. + X - R is selected from alkyl groups having 1 to 4 carbon atoms, preferably propyl, X - Selected from one or more of hydroxide ions, chloride ions, and bromide ions, preferably hydroxide ions; and / or

[0062] The first crystallization is carried out at 140–190°C and under autogenous pressure for 40–140 hours; preferably, the first crystallization is carried out at 175–185°C and under autogenous pressure for 96–120 hours.

[0063] Furthermore, in the first template agent, N is a nitrogen atom, and X... - Other halogen anions can also be used. By selecting the first template agent mentioned above and controlling the temperature and time of the first crystallization as described above, the grain size of the prepared alkali metal ion-type ZSM-5 molecular sieve can be better controlled. The resulting alkali metal ion-type ZSM-5 molecular sieve can be better combined with the other two types of molecular sieves, and the performance of the final catalyst is further improved.

[0064] In one embodiment of the method described above, the molar ratio of the second silicon source (calculated as SiO2), the second aluminum source (calculated as Al2O3), the second template agent, the second alkali, and water is 1:(0.005~0.05):(0.05~1.5):(0.02~0.5):(10~60).

[0065] It should be noted that, in the preparation of alkali metal ion-type Beta molecular sieves, the molar ratio of SiO2 / Al2O3 in the crystallization raw materials for the second crystallization is 20–200:1, preferably 25–150:1, that is, the molar ratio of the second silicon source (based on SiO2) to the second aluminum source (based on Al2O3) is 20–200:1, preferably 25–150:1. The molar ratio of the second silicon source (based on SiO2) to the second template agent is preferably 1:0.08–1.4. By controlling the molar ratios of the components as described above in the preparation of alkali metal ion-type Beta molecular sieves, the performance of the prepared alkali metal ion-type Beta molecular sieve can be improved. Furthermore, when combined with ZSM-5 and ZSM-48 molecular sieves, better synergistic effects can be achieved, and the p-xylene isomerization activity and xylene yield of the final catalyst can be further improved.

[0066] In one embodiment of the method described above, the second template agent is selected from quaternary ammonium bases and / or quaternary ammonium salts, and has the structural formula N(R)4. + X - R is selected from alkyl groups having 1 to 4 carbon atoms, preferably ethyl, X - Selected from one or more of hydroxide ions, chloride ions, and bromide ions, preferably hydroxide ions; and / or

[0067] The second crystallization is carried out at 120–180°C and under autogenous pressure for 60–140 hours; preferably, the second crystallization is carried out at 135–175°C and under autogenous pressure for 96–120 hours.

[0068] Furthermore, in the second template agent, N is a nitrogen atom, and X... - Other halogen anions can also be used. By selecting the second template agent mentioned above and controlling the temperature and time of the second crystallization as described above, the grain size of the prepared alkali metal ion-type Beta molecular sieve can be better controlled. The resulting alkali metal ion-type Beta molecular sieve can be better combined with the other two types of molecular sieves, and the performance of the final catalyst is further improved.

[0069] In another embodiment of the above method of the present invention, the molar ratio of the third silicon source (calculated as SiO2), the third aluminum source (calculated as Al2O3), the third template agent, the third alkali, and water is 1:(0.005~0.05):(0.01~1):(0.1~1):(10~60).

[0070] It should be noted that, in the preparation of alkali metal ion-type ZSM-48 molecular sieves, the molar ratio of SiO2 / Al2O3 in the crystallization raw materials for the third crystallization is 20–200:1, preferably 25–150:1. That is, the molar ratio of the third silicon source (based on SiO2) to the third aluminum source (based on Al2O3) is 20–200:1, preferably 25–150:1. The molar ratio of the third silicon source (based on SiO2) to the third template agent is preferably 1:0.02–0.9. By controlling the molar ratios of these components as described above in the preparation of alkali metal ion-type ZSM-48 molecular sieves, the molar ratio of SiO2 / Al2O3 and the molecular sieve performance can be controlled. When the resulting ZSM-48 molecular sieve is compounded with two other molecular sieves, it can achieve better synergistic effects, and the final catalyst's p-xylene isomerization activity and xylene yield can be further improved, resulting in better p-xylene selectivity.

[0071] In one embodiment of the method described above, the third template agent is hexamethylamine bromide and / or hexamethylenediamine; and / or

[0072] The third crystallization is carried out at 120–180°C and under autogenous pressure for 60–140 hours; preferably, the third crystallization is carried out at 160–180°C and under autogenous pressure for 96–120 hours.

[0073] In the method of the present invention, when preparing alkali metal ion type ZSM-48 molecular sieve, by controlling the crystallization temperature and time of the third crystallization as described above, and by selecting the third template agent mentioned above, the grain size and performance of the prepared alkali metal ion type ZSM-48 molecular sieve can be well controlled. The catalyst prepared by combining the obtained alkali metal ion type ZSM-48 molecular sieve with the above-mentioned alkali metal ion type ZSM-5 molecular sieve and Beta molecular sieve has better selectivity for p-xylene, and the p-xylene isomerization activity and xylene yield can be further improved.

[0074] In one embodiment of the method described above, the first silicon source, the second silicon source, and the third silicon source are each independently selected from liquid silica sol or solid silica gel; the concentration of the liquid silica sol is 10-40% by mass, preferably 30-40% by mass; the particle size of the solid silica gel is 0.005-0.5 mm, preferably 0.01-0.3 mm; and / or

[0075] The first aluminum source is aluminum nitrate nonahydrate; and / or

[0076] The second aluminum source is aluminum chloride; and / or

[0077] The third aluminum source is sodium aluminate and / or aluminum sulfate; and / or

[0078] The first base, the second base, and the third base are NaOH and / or KOH; and / or

[0079] The adhesive is aluminum oxide.

[0080] It should be noted that when the first, second, and third bases are NaOH, Na-type ZSM-5 molecular sieve, Na-type Beta molecular sieve, and Na-type ZSM-48 molecular sieve can be prepared according to the above method.

[0081] In one embodiment of the method described above, the grain size of the alkali metal ion type ZSM-5 molecular sieve is 0.05–10 μm, preferably 0.5–5 μm; the grain size of the alkali metal ion type Beta molecular sieve is 30–600 nm, preferably 50–300 nm; and the grain size of the alkali metal ion type ZSM-48 molecular sieve is 0.1–10 μm, preferably 0.2–2 μm.

[0082] In preparing the above three molecular sieves, by selecting the aforementioned silicon source, aluminum source, alkali, etc., and controlling the particle size of the three molecular sieves as described above, this invention facilitates the preparation of catalysts with high p-xylene isomerization activity and high xylene yield.

[0083] In another aspect, the present invention also provides a liquid-phase non-hydrogenated xylene isomerization method, comprising contacting a raw material containing alkyl aromatics with a catalyst under a reaction pressure that maintains a liquid state to carry out a liquid-phase non-hydrogenated xylene isomerization reaction; wherein the catalyst is the above-mentioned liquid-phase non-hydrogenated xylene isomerization catalyst, or is prepared by the above method;

[0084] Preferably, the liquid-phase non-hydroxylene isomerization reaction is carried out at 240–310 °C and a weight hourly space velocity of 1–10 h⁻¹. -1 The following will proceed.

[0085] In the liquid-phase non-hydroxylene isomerization method of this invention, a certain pressure is controlled within the reactor while maintaining a specific reaction temperature to keep the alkyl aromatics in a liquid state in contact with the catalyst for the liquid-phase non-hydroxylene isomerization reaction. Compared with gas-phase xylene isomerization, the liquid-phase non-hydroxylene isomerization method of this invention achieves higher isomerization activity and xylene yield while requiring a lower reaction temperature, significantly reducing energy consumption, and being more environmentally friendly. The alkyl aromatics preferably contain C8 aromatics. The catalyst provided by this invention is used for the isomerization of C8 aromatics, which can increase the production of para-xylene while maintaining good selectivity.

[0086] The present invention will be further described in detail below through embodiments, but these embodiments do not limit the scope of the invention. Unless otherwise specified, the experimental instruments and raw materials involved in the following embodiments are commercially available products.

[0087] Example 1

[0088] Add 30g of silicon source (liquid silica sol, concentration 30% by mass), 3.75g of aluminum source (aluminum nitrate nonahydrate), and 4g of template agent N(C3H7) to a 200mL reactor. + OH - The molecular sieve consisted of 81.34 g of a 25% (w / w) aqueous solution, 0.8 g of NaOH, and 0.972 g of water. The molar ratio of the reactants was Al₂O₃:template:NaOH:H₂O:SiO₂ = 0.033:0.67:0.13:31.33:1. The synthesis temperature was 175℃, and the synthesis time was 120 hours. A homogeneous reactor dynamic synthesis method was used to synthesize the molecular sieve. The molecular sieve was washed and dried.

[0089] The obtained ZSM-5 molecular sieve, denoted as Z-1, has a silica-to-alumina ratio of 30 and an average grain size of 0.75 μm. The XRD diffraction pattern is attached. Figure 1Strong diffraction peaks appeared at 2θ of 7.9°, 8.8°, 23.1°, and 23.3°, which are typical characteristic peaks of ZSM-5 molecular sieves, representing the (011), (020), (332), and (051) crystal planes of ZSM-5 molecular sieves, respectively, indicating that the catalyst has a typical MFI structure. Meanwhile, the XRD pattern showed a stable baseline and no impurity peaks, indicating the synthesis of a well-crystallized ZSM-5 molecular sieve. Its SEM characterization is shown in the appendix. Figure 4 .

[0090] Add 15g of silicon source (solid silica gel, particle size 150-250μm, pore size 6nm), 2.22g of aluminum source (aluminum chloride), and 4g of template agent N(C2H5) to a 200mL reactor. + OH - The molecular sieve consisted of 70.14 g of a 35% (w / w) aqueous solution, 1.33 g of NaOH, and 26.41 g of water. The molar ratio of the reactants was Al₂O₃:template:NaOH:H₂O:SiO₂ = 0.033:0.67:0.13:16:1. The synthesis temperature was 135℃, and the synthesis time was 115 hours. A homogeneous reactor dynamic synthesis method was used to synthesize the molecular sieve. The molecular sieve was washed and dried.

[0091] The obtained Beta molecular sieve, designated B-1, has a silica-to-alumina ratio of 30 and an average grain size of 230 nm. The XRD diffraction pattern is attached. Figure 2 It can be seen that the synthesized molecular sieve is a pure phase sieve, which not only has high crystallinity and stable baseline, but also exhibits a series of characteristic peaks at 2θ of 7.6°, 13.2°, 14.6°, 21.2°, 22.4°, 25.2°, 26.8°, and 29.5°. These are characteristic diffraction peaks of Beta molecular sieve, corresponding to the characteristic peaks of the (330), (302), (304), (008), and (306) crystal planes of Beta molecular sieve, respectively. No other impurity peaks are present in the XRD pattern, indicating that the synthesized Beta molecular sieve is a pure phase product. Its SEM characterization is shown in the appendix. Figure 5 .

[0092] 25 g of silicon source (liquid silica sol, concentration 40% by mass), 0.911 g of aluminum source (sodium aluminate), 6.037 g of hexamethylammonium bromide as a template agent, 1.333 g of NaOH, and 65 g of water were added to a 200 mL reactor. The molar ratio of the added substances was Al₂O₃:template agent:NaOH:H₂O:SiO₂ = 0.033:0.1:0.2:26.67:1. The synthesis temperature was 180℃, and the synthesis time was 100 hours, using a static synthesis method to synthesize the molecular sieve. The molecular sieve was washed and dried.

[0093] The obtained ZSM-48 molecular sieve, denoted as S-1, has a silicon-to-aluminum ratio of 30 and an average grain size of 1.8 μm. The XRD diffraction pattern is attached. Figure 3 Typical characteristic diffraction peaks of ZSM-48 were observed at 2θ values ​​of 7.6°, 15°, 21°, 22.7°, and 31.2°. Simultaneously, the XRD pattern showed a stable baseline with no extraneous peaks, indicating the synthesis of well-crystallized ZSM-48 molecular sieve. Its SEM characterization is shown in the appendix. Figure 6 .

[0094] ZSM-5 molecular sieve Z-1, Beta molecular sieve B-1, and ZSM-48 molecular sieve S-1 were thoroughly mixed with alumina at a mass ratio of 5:1:1:3. A 5% (w / w) nitric acid aqueous solution was added and kneaded until homogeneous, with the nitric acid aqueous solution accounting for 35% of the mass of the solid mixture. The mixture was then extruded into strips. The strips were dried at 120℃ for 6 hours, then granulated and calcined at 540℃ for 4 hours. The calcined sample was subjected to ion exchange with a 5% (w / w) ammonium chloride aqueous solution at 90℃ for 2 hours, washed until no chloride ions were present in the mother liquor, dried at 120℃ for 6 hours, and calcined at 540℃ for 4 hours to obtain catalyst C-1.

[0095] Example 2

[0096] Add 30g of silicon source (liquid silica sol, concentration 30% by mass), 1.88g of aluminum source (aluminum nitrate nonahydrate), and N(C3H7)4 to a 200mL reactor. + OH - 61g (25% by mass aqueous solution), 0.6g NaOH, and 0.834g water were added. The molar ratio of the added substances was Al2O3:template:NaOH:H2O:SiO2 = 0.017:0.5:0.1:25.33:1. The synthesis temperature was 180℃, and the synthesis time was 96 hours. The molecular sieve was synthesized using a homogeneous reactor dynamic synthesis method. The molecular sieve was washed and dried.

[0097] The obtained ZSM-5 molecular sieve, designated Z-2, has a silica-to-alumina ratio of 60 and an average grain size of 0.52 μm. The XRD diffraction pattern is attached. Figure 1 Strong diffraction peaks appeared at 2θ of 7.9°, 8.8°, 23.1°, and 23.3°, which are typical characteristic peaks of ZSM-5 molecular sieves. These peaks represent the (011), (020), (332), and (051) crystal planes of H-type ZSM-5 molecular sieves, respectively, indicating that the catalyst has a typical MFI structure. Meanwhile, the XRD pattern showed a stable baseline and no impurity peaks, indicating the synthesis of a well-crystallized ZSM-5 molecular sieve. Its SEM characterization is shown in the appendix. Figure 4 .

[0098] Add 15g of silicon source (solid silica gel, particle size 150-250μm, pore size 6nm), 1.11g of aluminum source (aluminum chloride), and 4g of template agent N(C2H5) to a 200mL reactor. + OH - The molecular sieve consisted of 52.61 g of a 35% (w / w) aqueous solution, 0.5 g of NaOH, and 46.81 g of water. The molar ratio of the additives was Al₂O₃:template:NaOH:H₂O:SiO₂ = 0.017:0.5:0.05:18:1. The synthesis temperature was 140℃, and the synthesis time was 115 hours. A homogeneous reactor dynamic synthesis method was used to synthesize the molecular sieve. The molecular sieve was washed and dried.

[0099] The obtained Beta molecular sieve, designated B-2, has a silica-to-alumina ratio of 60 and an average grain size of 180 nm. The XRD diffraction pattern is attached. Figure 2 It can be seen that the synthesized molecular sieve is a pure phase sieve, which not only has high crystallinity and stable baseline, but also exhibits a series of characteristic peaks at 2θ of 7.6°, 13.2°, 14.6°, 21.2°, 22.4°, 25.2°, 26.8°, and 29.5°. These are characteristic diffraction peaks of Beta molecular sieve, corresponding to the characteristic peaks of the (330), (302), (304), (008), and (306) crystal planes of Beta molecular sieve, respectively. No other impurity peaks are present in the XRD pattern, indicating that the synthesized Beta molecular sieve is a pure phase product. Its SEM characterization is shown in the appendix. Figure 5 .

[0100] In a 200 mL reactor, 33.33 g of silicon source (liquid silica sol, 30% by mass), 0.455 g of aluminum source (sodium aluminate), 3.018 g of hexamethylammonium bromide as a template agent, 1.111 g of NaOH, and 66.67 g of water were added. The molar ratio of the added substances was Al₂O₃:template agent:NaOH:H₂O:SiO₂ = 0.0167:0.05:0.167:30:1. The molecular sieve was synthesized using a static synthesis method at 175 °C for 105 hours. The molecular sieve was then washed and dried.

[0101] The obtained ZSM-48 molecular sieve, designated S-2, has a silica-to-alumina ratio of 60 and an average grain size of 1.4 μm. The XRD diffraction pattern is attached. Figure 3 Typical characteristic diffraction peaks of ZSM-48 were observed at 2θ values ​​of 7.6°, 15°, 21°, 22.7°, and 31.2°. Simultaneously, the XRD pattern showed a stable baseline with no extraneous peaks, indicating the synthesis of well-crystallized ZSM-48 molecular sieve. Its SEM characterization is shown in the appendix. Figure 6 .

[0102] ZSM-5 molecular sieve Z-2, Beta molecular sieve B-2, ZSM-48 molecular sieve S-2, and alumina were thoroughly mixed at a mass ratio of 4:2:1:3. Catalyst C-2 was then obtained according to the catalyst preparation method described in Example 1.

[0103] Example 3

[0104] Add 22.5 g of silicon source (liquid silica sol, concentration 40% by mass), 1.406 g of aluminum source (aluminum nitrate nonahydrate), and 4 g of template agent N(C3H7) to a 200 mL reactor. + OH - The molecular sieve consisted of 30.504 g of a 25% (w / w) aqueous solution, 0.45 g of NaOH, and 0.814 g of water. The molar ratio of the reactants was Al₂O₃:template:NaOH:H₂O:SiO₂ = 0.0125:0.25:0.075:14:1. The synthesis temperature was 180℃, and the synthesis time was 100 hours. A homogeneous reactor dynamic synthesis method was used to synthesize the molecular sieve. The molecular sieve was washed and dried.

[0105] The obtained ZSM-5 molecular sieve, designated Z-3, has a silica-to-alumina ratio of 80 and an average grain size of 0.79 μm. The XRD diffraction pattern is attached. Figure 1 Strong diffraction peaks appeared at 2θ of 7.9°, 8.8°, 23.1°, and 23.3°, which are typical characteristic peaks of ZSM-5 molecular sieves. These peaks represent the (011), (020), (332), and (051) crystal planes of H-type ZSM-5 molecular sieves, respectively, indicating that the catalyst has a typical MFI structure. Meanwhile, the XRD pattern showed a stable baseline and no impurity peaks, indicating the synthesis of a well-crystallized ZSM-5 molecular sieve. Its SEM characterization is shown in the appendix. Figure 4 .

[0106] Add 15g of silicon source (solid silica gel, particle size 150-250μm, pore size 6nm), 0.833g of aluminum source (aluminum chloride), and 4g of template agent N(C2H5) to a 200mL reactor. + OH - The molecular sieve consisted of 39.46 g of a 35% (w / w) aqueous solution, 0.375 g of NaOH, and 41.85 g of water. The molar ratio of the additives was Al₂O₃:template:NaOH:H₂O:SiO₂ = 0.0125:0.375:0.0375:15:1. The synthesis temperature was 155℃, and the synthesis time was 105 hours. A homogeneous reactor dynamic synthesis method was used to synthesize the molecular sieve. The molecular sieve was washed and dried.

[0107] The obtained Beta molecular sieve, designated B-3, has a silica-to-alumina ratio of 80 and an average grain size of 100 nm. The XRD diffraction pattern is attached. Figure 2It can be seen that the synthesized molecular sieve is a pure phase sieve, which not only has high crystallinity and stable baseline, but also exhibits a series of characteristic peaks at 2θ of 7.6°, 13.2°, 14.6°, 21.2°, 22.4°, 25.2°, 26.8°, and 29.5°. These are characteristic diffraction peaks of Beta molecular sieve, corresponding to the characteristic peaks of the (330), (302), (304), (008), and (306) crystal planes of Beta molecular sieve, respectively. No other impurity peaks are present in the XRD pattern, indicating that the synthesized Beta molecular sieve is a pure phase product. Its SEM characterization is shown in the appendix. Figure 5 .

[0108] In a 200 mL reactor, 33.33 g of silicon source (liquid silica sol, 30% by mass), 0.342 g of aluminum source (sodium aluminate), 4.527 g of hexamethylammonium bromide as a template agent, 1.333 g of NaOH, and 51.667 g of water were added. The molar ratio of the added substances was Al₂O₃:template agent:NaOH:H₂O:SiO₂ = 0.0125:0.075:0.2:25:1. The molecular sieve was synthesized using a static synthesis method at 180℃ for 96 hours. The molecular sieve was then washed and dried.

[0109] The obtained ZSM-48 molecular sieve, designated S-3, has a silica-to-alumina ratio of 80 and an average grain size of 1.05 μm. The XRD diffraction pattern is attached. Figure 3 Typical characteristic diffraction peaks of ZSM-48 were observed at 2θ values ​​of 7.6°, 15°, 21°, 22.7°, and 31.2°. Simultaneously, the XRD pattern showed a stable baseline with no extraneous peaks, indicating the synthesis of well-crystallized ZSM-48 molecular sieve. Its SEM characterization is shown in the appendix. Figure 6 .

[0110] ZSM-5 molecular sieve Z-3, Beta molecular sieve B-3, ZSM-48 molecular sieve S-3, and alumina were thoroughly mixed at a mass ratio of 3:2:2:3. Catalyst C-3 was then obtained according to the catalyst preparation method described in Example 1.

[0111] Example 4

[0112] Catalyst C-4 was obtained according to the catalyst preparation method in Example 1, except that the mass ratio of ZSM-5 molecular sieve Z-1, Beta molecular sieve B-1, ZSM-48 molecular sieve S-1 to alumina was 3:1:3:3.

[0113] Example 5

[0114] Catalyst C-5 was obtained according to the catalyst preparation method in Example 2, except that the mass ratio of ZSM-5 molecular sieve Z-2, Beta molecular sieve B-2, ZSM-48 molecular sieve S-2 to alumina was 2:3:2:3.

[0115] Example 6

[0116] Catalyst C-6 was obtained according to the catalyst preparation method in Example 3, except that the mass ratio of ZSM-5 molecular sieve Z-3, Beta molecular sieve B-3, ZSM-48 molecular sieve S-3 to alumina was 1:3:3:3.

[0117] Comparative Example 1

[0118] Catalyst D-1 was obtained according to the catalyst preparation method in Example 1, except that ZSM-5 molecular sieve and ZSM-48 molecular sieve were not added to the catalyst, and the mass ratio of Beta molecular sieve B-1 to alumina was 7:3.

[0119] Comparative Example 2

[0120] Catalyst D-2 was obtained according to the catalyst preparation method in Example 1, except that Beta molecular sieve and ZSM-48 molecular sieve were not added to the catalyst, and the mass ratio of ZSM-5 molecular sieve Z-1 to alumina was 7:3.

[0121] Comparative Example 3

[0122] Catalyst D-3 was obtained according to the catalyst preparation method in Example 3, except that Beta molecular sieve and ZSM-5 molecular sieve were not added to the catalyst, and the mass ratio of ZSM-48 molecular sieve S-3 to alumina was 7:3.

[0123] Comparative Example 4

[0124] Catalyst D-4 was obtained according to the catalyst preparation method in Example 2, except that ZSM-5 molecular sieve was not added to the catalyst, and the mass ratio of Beta molecular sieve B-2, ZSM-48 molecular sieve S-1 to alumina was 3:4:3.

[0125] Comparative Example 5

[0126] Catalyst D-5 was obtained according to the catalyst preparation method in Example 2, except that Beta molecular sieve was not added to the catalyst, and the mass ratio of ZSM-5 molecular sieve Z-3, ZSM-48 molecular sieve S-2 to alumina was 2:5:3.

[0127] Comparative Example 6

[0128] Catalyst D-6 was obtained according to the catalyst preparation method in Example 3, except that ZSM-48 molecular sieve was not added to the catalyst, and the mass ratio of ZSM-5 molecular sieve Z-3, Beta molecular sieve B-3 and alumina was 1:6:3.

[0129] Test Implementation Examples

[0130] In a small, continuously flowing fixed-bed reactor, 3 grams of catalyst were loaded, and the catalyst performance was evaluated using feedstocks with the compositions shown in Table 1. The evaluation conditions were: 240°C, 2 MPa, and a feed mass hourly space velocity (MHSV) of 2 h⁻¹. -1 .

[0131] Table 1 Raw Material Composition

[0132] <![CDATA[C8NA]]> B T EB PX MX OX <![CDATA[C9 + ]]> 0.355％ 0.000％ 0.000％ 4.760％ 0.085％ 65.194％ 29.531％ 0.000％

[0133] Catalyst performance was evaluated using the following calculation method:

[0134] Isomerization activity indicators: Xylene yield: The catalysts used in each embodiment and comparative example and the reaction results are shown in Tables 2 and 3.

[0135] Table 2 Catalysts and Reaction Performance Used in Examples (Table 2)

[0136]

[0137] Table 3 Catalysts and reaction performance of the comparative examples

[0138]

[0139] As shown in Tables 2 and 3, the catalysts prepared by the methods of Examples 1 to 6 of the present invention have higher isomerization activity (PX / ∑X) and higher xylene yield than the catalysts of Comparative Examples 1 to 6. This indicates that the method of the present invention, which uses a combination of three molecular sieves as the active component of the catalyst, has better isomerization activity and selectivity than using only one or two molecular sieves as the active component.

[0140] 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 liquid-phase non-hydrogenated xylene isomerization catalyst, comprising 10-80% H-type molecular sieve and 20-90% binder, based on the total mass of the liquid-phase non-hydrogenated xylene isomerization catalyst; in, The H-type molecular sieve comprises the following components in the following proportions based on the total mass of the H-type molecular sieve: ZSM-5 molecular sieve 5-90% Beta molecular sieve 5-90% ZSM-48 molecular sieve: 5-90%.

2. A method for preparing the liquid-phase non-hydroxylene isomerization catalyst of claim 1, wherein, Includes the following steps: (1) Provide alkali metal ion type ZSM-5 molecular sieve; (2) Provide alkali metal ion type Beta molecular sieves; (3) Provide alkali metal ion type ZSM-48 molecular sieve; (4) The alkali metal ion type ZSM-5 molecular sieve, the alkali metal ion type Beta molecular sieve and the alkali metal ion type ZSM-48 molecular sieve are mixed with a binder and then added to an acid solution for kneading, molding and first calcination. Then, they are contacted with an ammonium salt solution for ion exchange and second calcination to obtain the liquid phase non-hydroxylene isomerization catalyst.

3. The method according to claim 2, wherein, The preparation method of the alkali metal ion type ZSM-5 molecular sieve in step (1) includes: The first silicon source, the first aluminum source, the first template agent, the first alkali, and water are mixed and subjected to first crystallization. The solid phase is then washed and dried to obtain the alkali metal ion-type ZSM-5 molecular sieve; and / or The preparation method of the alkali metal ion type Beta molecular sieve in step (2) includes: A second silicon source, a second aluminum source, a second template agent, a second alkali, and water are mixed and subjected to a second crystallization. The solid phase is then washed and dried to obtain the alkali metal ion-type Beta molecular sieve; and / or The preparation method of the alkali metal ion type ZSM-48 molecular sieve in step (3) includes: The third silicon source, third aluminum source, third template agent, third alkali, and water are mixed and subjected to third crystallization. The solid phase is then washed and dried to obtain the alkali metal ion-type ZSM-48 molecular sieve; and / or Step (4) further includes a first drying between the molding and the first calcination; and / or Step (4) also includes washing and second drying between the ion exchange and the second calcination.

4. The method according to claim 3, wherein, The molar ratio of the first silicon source (calculated as SiO2), the first aluminum source (calculated as Al2O3), the first template agent, the first alkali, and water is 1:(0.005~0.05):(0.05~1):(0.02~1):(10~60).

5. The method according to claim 3, wherein, The first template agent is selected from quaternary ammonium bases and / or quaternary ammonium salts, and has the structural formula N(R)4. + X - R is selected from alkyl groups having 1 to 4 carbon atoms, preferably propyl, X - Selected from one or more of hydroxide ions, chloride ions, and bromide ions, preferably hydroxide ions; and / or The first crystallization is carried out at 140–190°C and under autogenous pressure for 40–140 hours; preferably, the first crystallization is carried out at 175–185°C and under autogenous pressure for 96–120 hours.

6. The method according to claim 3, wherein, The molar ratio of the second silicon source (calculated as SiO2), the second aluminum source (calculated as Al2O3), the second template agent, the second alkali, and water is 1:(0.005~0.05):(0.05~1.5):(0.02~0.5):(10~60).

7. The method according to claim 3, wherein, The second template agent is selected from quaternary ammonium bases and / or quaternary ammonium salts, and has the structural formula N(R)4. + X - R is selected from alkyl groups having 1 to 4 carbon atoms, preferably ethyl, X - Selected from one or more of hydroxide ions, chloride ions, and bromide ions, preferably hydroxide ions; and / or The second crystallization is carried out at 120–180°C and under autogenous pressure for 60–140 hours; preferably, the second crystallization is carried out at 135–175°C and under autogenous pressure for 96–120 hours.

8. The method according to claim 3, wherein, The molar ratio of the third silicon source (calculated as SiO2), the third aluminum source (calculated as Al2O3), the third template agent, the third alkali, and water is 1:(0.005~0.05):(0.01~1):(0.1~1):(10~60).

9. The method according to claim 3, wherein, The third template agent is hexamethylamine bromide and / or hexamethylenediamine; and / or The third crystallization is carried out at 120–180°C and under autogenous pressure for 60–140 hours; preferably, the third crystallization is carried out at 160–180°C and under autogenous pressure for 96–120 hours.

10. The method according to claim 3, wherein, The first silicon source, the second silicon source, and the third silicon source are each independently selected from liquid silica sol or solid silica gel; the concentration of the liquid silica sol is 10-40% by mass, preferably 30-40% by mass; the particle size of the solid silica gel is 0.005-0.5 mm, preferably 0.01-0.3 mm; and / or The first aluminum source is aluminum nitrate nonahydrate; and / or The second aluminum source is aluminum chloride; and / or The third aluminum source is sodium aluminate and / or aluminum sulfate; and / or The first base, the second base, and the third base are NaOH and / or KOH; and / or The adhesive is aluminum oxide.

11. The method according to claim 2, wherein, The crystal size of the alkali metal ion type ZSM-5 molecular sieve is 0.05–10 μm, preferably 0.5–5 μm; the crystal size of the alkali metal ion type Beta molecular sieve is 30–600 nm, preferably 50–300 nm; and the crystal size of the alkali metal ion type ZSM-48 molecular sieve is 0.1–10 μm, preferably 0.2–2 μm.

12. A method for liquid-phase non-hydroxylene isomerization, comprising contacting a feedstock containing alkyl aromatics with a catalyst under a reaction pressure maintaining a liquid state to carry out a liquid-phase non-hydroxylene isomerization reaction; wherein, The catalyst is the liquid-phase non-hydrogenated xylene isomerization catalyst of claim 1, or is prepared by the method of any one of claims 2 to 11; Preferably, the liquid-phase non-hydroxylene isomerization reaction is carried out at 240–310 °C and a weight hourly space velocity of 1–10 h⁻¹. -1 The following will proceed.

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