Preparation method of 3D printed molecular sieve catalyst and 3D printed molecular sieve catalyst prepared by the method and application thereof

Abstract

The present application relates to the field of molecular sieve catalyst, disclose a kind of preparation method of 3D printing molecular sieve catalyst and the 3D printing molecular sieve catalyst prepared and application, the method is by hydrothermal crystallization to silicate ceramic carrier in crystallization incubation fluid, it can be obtained on silicate ceramic carrier good dispersion, catalytic activity high molecular sieve, preparation process is simple, can not depend on mold to form complex three-dimensional structure, the structure precision of molecular sieve catalyst prepared is high, the content of molecular sieve in catalyst is high, metal in catalyst is supported on molecular sieve, molecular sieve is exposed to the outer surface of catalyst, metal site and molecular sieve acidic active site both have higher accessibility, and catalytic activity is high.

Description

Technical Field

[0001] This invention relates to the field of molecular sieve catalysts, specifically to a method for preparing a 3D-printed molecular sieve catalyst, the obtained 3D-printed molecular sieve catalyst, and its application. Background Technology

[0002] In the fields of materials science and heterogeneous catalysis, nano-metal catalysts have become a research hotspot due to their unique electronic structure, high specific surface area, and excellent catalytic activity, and are widely used in reactions such as small molecule activation and hydrocarbon cracking. However, since the surface energy of metal species increases with decreasing size, metal species dispersed in traditional open structures are thermodynamically unstable and prone to sintering under conditions such as thermal activation, leading to rapid deactivation and limiting their practical applications. To improve the stability of metal species, confining the active metal sites within the pores or cavities of porous materials such as molecular sieves helps control metal size, improve metal species dispersion, and inhibit their migration and aggregation, thereby improving the thermal and catalytic stability of the metal. ZSM-5 belongs to the MFI family of molecular sieves and has straight channels. and sine channel With tunable acidity, high thermal / hydrothermal stability, and unique shape-selective catalytic effects, ZSM-5 molecular sieves are among the most widely used solid acid catalysts currently available. Several metal ZSM-5 molecular sieves have been reported for applications in catalytic cracking, isomerization, cyclization, and aromatization reactions (ACSCatalysis 2016, 6, 8321; ACS Catalysis 2023, 13, 1; Energy & Fuels, 2016, 30, 5259). In recent years, with the soaring prices of precious metals, the development of non-precious metal molecular sieve catalysts has gradually become a hot topic.

[0003] CN201911367038.1 describes the preparation of ZSM-5 molecular sieves containing lanthanum and zinc and / or nickel within their pores via hydrothermal synthesis. The prepared molecular sieves also contain a large number of mesopores, which can improve the diffusion rate of macromolecular reactants or products and enhance the catalyst's carbon-carrying capacity. CN202010226208.0 describes the integration of molecular sieve synthesis and metal loading into a single step, combined with dry gel conversion, to achieve the preparation of molecular sieve-supported metal catalysts, resulting in the uniform dispersion of active metals within the micropores of the molecular sieve. Busca et al. reported a metal-supported molecular sieve (Fuel Processing Technology 2015, 137, 290–297) that achieved selective control of ethanol catalytic conversion products by loading non-noble metal Ni species onto a hydrogen-form ZSM-5 molecular sieve.

[0004] However, the aforementioned research systems all involve powdered molecular sieve materials. In practical applications, metal-loaded molecular sieve powders need to be co-processed with binders / matrix materials into shaped catalysts such as microspheres, particles, or strips before they can be used. The structure, composition, and catalytic performance of the shaped catalysts will differ significantly from the initial molecular sieve powder. Therefore, optimizing the catalyst shaping method to improve the accessibility of active sites in metal-loaded molecular sieve catalysts and thus enhance reaction performance is a crucial issue in the research and development and production of molecular sieve catalysts. In this regard, developing a shaped catalyst preparation route with easily accessible metal and molecular sieve active sites has significant practical implications and application value. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem of low accessibility between the metal and the active sites of the molecular sieve in the metal-supported ZSM-5 molecular sieve catalyst in the prior art, and to provide a method for preparing a 3D printed molecular sieve catalyst, as well as the molecular sieve catalyst and its application. The preparation method is simple, the metal is supported on the molecular sieve in the catalyst, and the molecular sieve is exposed on the outer surface of the catalyst. Both the metal sites and the acidic active sites of the molecular sieve have high accessibility, resulting in high catalytic activity.

[0006] To achieve the above objectives, the first aspect of the present invention provides a method for preparing a 3D-printed molecular sieve catalyst, wherein the method includes the following steps:

[0007] (1) Provide an aluminosilicate photosensitive resin slurry containing aluminosilicate and photosensitive resin, and then perform 3D printing to obtain an aluminosilicate ceramic blank;

[0008] (2) The aluminosilicate ceramic blank is sintered to obtain an aluminosilicate ceramic carrier;

[0009] (3) Crystallize the crystallization mother liquor containing silicon source, aluminum source, template agent, alkali source and water to obtain crystallization incubation solution;

[0010] (4) The aluminosilicate ceramic support is hydrothermally crystallized in a crystallization incubation solution, and then the solid product obtained by hydrothermal crystallization is first calcined to obtain a sodium-type molecular sieve catalyst.

[0011] (5) The sodium-type molecular sieve catalyst is subjected to ammonium exchange to obtain a hydrogen-type molecular sieve catalyst;

[0012] (6) The hydrogen-type molecular sieve catalyst is impregnated with a nickel salt solution, and then the solid product obtained by impregnation is subjected to a second calcination to obtain a 3D printed molecular sieve catalyst.

[0013] The second aspect of this invention provides a 3D-printed molecular sieve catalyst prepared by the preparation method described in the first aspect.

[0014] Preferably, the 3D printing molecular sieve catalyst comprises ZSM-5 molecular sieve with a mass percentage of 20-55%.

[0015] Preferably, the ZSM-5 molecular sieve is distributed on the surface of the 3D printed molecular sieve catalyst and exists in the form of micron-sized particle aggregates, with the average particle size of the micron-sized particles preferably being 1-5 microns.

[0016] Preferably, the nickel content in the 3D printed molecular sieve catalyst is 0.5-10% by mass, and more preferably 2-8%.

[0017] Preferably, the micropore volume of the 3D-printed molecular sieve catalyst is 0.04-0.1 cm. 3 / g; mesopore volume is 0.04-0.09cm³ 3 / g.

[0018] The third aspect of this invention provides the application of a 3D-printed molecular sieve catalyst prepared by the method described in the first aspect or the 3D-printed molecular sieve catalyst described in the second aspect in a catalytic cracking reaction.

[0019] Through the above technical solution, the present invention has the following advantages:

[0020] (1) The preparation method provided by the present invention can establish a model through three-dimensional software, and can be customized to suit complex three-dimensional structures in different scenarios. It does not rely on high-cost mold opening, nor does it require complex post-processing such as cutting and shaving of the carrier. The three-dimensional channel structure of the carrier is simple and controllable.

[0021] (2) The molecular sieve catalyst prepared by the preparation method provided by the present invention has a high molecular sieve content and high structural precision. Moreover, the molecular sieve is directly exposed on the outer surface of the support through in-situ growth, which has the advantage of high accessibility of the active center.

[0022] (3) In the molecular sieve catalyst prepared by the preparation method provided by the present invention, the molecular sieve is generated in situ on the surface of the support, and the metallic nickel is dispersed in the molecular sieve (microporous aluminosilicate crystal) and is also directly exposed on the outer surface of the support, which has the advantage of high accessibility of metal sites; the use of metallic nickel has dehydrogenation activity and has the advantage of low cost as a non-precious metal; the molecular sieve catalyst is easy to separate and recover from the synthesis solution, and the synthesis process has low equipment requirements;

[0023] (4) In this invention, the molecular sieve catalyst prepared has high catalytic activity in the performance test of hydrocarbon catalytic cracking reaction and has the advantage of reducing bed pressure drop, and has application prospects in the field of catalytic cracking. Attached Figure Description

[0024] Figure 1 This is a three-dimensional model structure diagram established in Example 1;

[0025] Figure 2 This is a photograph of the 3D-printed molecular sieve catalyst prepared in Example 1;

[0026] Figure 3 This is the XRD pattern of the 3D-printed molecular sieve catalyst prepared in Example 1;

[0027] Figure 4 This is a scanning electron microscope image of the 3D-printed molecular sieve catalyst prepared in Example 1;

[0028] Figure 5 This is a transmission electron microscope image of the 3D-printed molecular sieve catalyst prepared in Example 1;

[0029] Figure 6 This is an EDS-Mapping elemental distribution diagram of the 3D-printed molecular sieve catalyst prepared in Example 1;

[0030] Figure 7 The isothermal adsorption curves of the 3D-printed molecular sieve catalyst prepared in Example 1 are shown.

[0031] Figure 8 This is the pore distribution curve of the 3D printed molecular sieve catalyst prepared in Example 1. Detailed Implementation

[0032] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0033] The first aspect of this invention provides a method for preparing a 3D-printed molecular sieve catalyst, the method comprising the following steps:

[0034] (1) Provide an aluminosilicate photosensitive resin slurry containing aluminosilicate and photosensitive resin, and then perform 3D printing to obtain an aluminosilicate ceramic blank;

[0035] (2) The aluminosilicate ceramic blank is sintered to obtain an aluminosilicate ceramic carrier;

[0036] (3) Crystallize the crystallization mother liquor containing silicon source, aluminum source, template agent, alkali source and water to obtain crystallization incubation solution;

[0037] (4) The aluminosilicate ceramic support is hydrothermally crystallized in a crystallization incubation solution, and then the solid product obtained by hydrothermal crystallization is first calcined to obtain a sodium-type molecular sieve catalyst.

[0038] (5) The sodium-type molecular sieve catalyst is subjected to ammonium exchange to obtain a hydrogen-type molecular sieve catalyst;

[0039] (6) The hydrogen-type molecular sieve catalyst is impregnated with a nickel salt solution, and then the solid product obtained by impregnation is subjected to a second calcination to obtain a 3D printed molecular sieve catalyst.

[0040] In this invention, aluminosilicate ceramic support is hydrothermally crystallized in a crystallization incubation solution, which can obtain molecular sieves with good dispersibility and high catalytic activity on the aluminosilicate ceramic support. The preparation process is simple, and complex three-dimensional structures can be formed without relying on molds. The resulting molecular sieve catalyst has high structural precision, high molecular sieve content, and high catalytic activity.

[0041] In this invention, preferably, the aluminosilicate photosensitive resin slurry in step (1) can be obtained by mixing aluminosilicate and photosensitive resin. There is no particular limitation on the mixing method. According to a preferred embodiment of this invention, the mixing can be achieved by ball milling, with a ball milling speed of 250-500 rpm, preferably 280-450 rpm, and a ball milling time of 3-18 hours, preferably 5-15 hours.

[0042] According to the present invention, preferably, the aluminosilicate comprises silicon-based powder and auxiliary powder, wherein the mass percentage of silicon-based powder on a dry basis is 35-65%, preferably 45-60%, and the mass percentage of auxiliary powder on a dry basis is 35-65%, preferably 40-55%. Using this preferred composition of aluminosilicate is more beneficial for the carrier material obtained after sintering to balance structural stability and chemical activity under hydrothermal conditions.

[0043] In this invention, the term aluminosilicate has the conventional meaning in the art. Aluminosilicate is a class of substances, including commonly used mineral soils, whose main components are aluminum oxide and silicon dioxide. Its molecular formula can be represented by xAl2O3·ySiO2, wherein the ratio of aluminum oxide to silicon dioxide is not constant.

[0044] In this invention, the particle size of the aluminosilicate is not particularly limited; it can be either large particles or small powders, as long as the aluminosilicate is uniformly distributed in the carrier. If larger particles are used, it is preferable to further improve their uniformity through subsequent ball milling. Preferably, the particle size D90 of the aluminosilicate is in the range of 0.5-100 μm.

[0045] In this invention, preferably, the aforementioned silicon-based powder is mixed with auxiliary powder to obtain aluminosilicate. The silicon-based powder can be used as a silicon source for growing molecular sieves on a support in subsequent preparation processes. When the amount of silicon-based powder added is too large, the silicon dissolution degree of the support during hydrothermal crystallization after sintering is too high, resulting in an excessively high in-situ molecular sieve growth reaction rate on the support surface, which makes the support structure unstable and causes it to collapse, no longer maintaining its original self-supporting structure. When the amount of silicon-based powder added is insufficient, the silicon dissolution of the support during hydrothermal crystallization after sintering is limited, resulting in an excessively low in-situ molecular sieve growth reaction rate on the support surface, leading to a low molecular sieve content in the final catalyst, which cannot meet the requirements of the catalytic reaction.

[0046] In this invention, there is no particular limitation on the particle size of the silicon-based powder and the auxiliary powder; it is preferred that the particle size of the aluminosilicate obtained after mixing meets the above-mentioned particle size requirements.

[0047] According to the present invention, the silicon-based powder can be a conventional silicon-based powder in the art, and those skilled in the art can make adaptive selections as needed. Preferably, the silicon-based powder is selected from at least one of silicon dioxide, silica, and diatomaceous earth.

[0048] According to the present invention, there are no particular limitations on the auxiliary powder, as long as it functions to maintain the stability of the self-supporting structure under hydrothermal conditions. Preferably, the auxiliary powder is selected from at least one of kaolin, metakaolin, bentonite, and montmorillonite.

[0049] According to the present invention, the range of the amounts of the aluminosilicate and the photosensitive resin is relatively wide, so as to ensure that the 3D printing process can proceed smoothly. Preferably, the mass ratio of the aluminosilicate to the photosensitive resin is 0.5-1:1, for example, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, and any range between any two values, preferably 0.6-0.9:1.

[0050] According to the present invention, the specific composition of the photosensitive resin can be selected within a wide range and can be selected according to conventional technical means in the art. Preferably, the raw materials of the photosensitive resin include 1-5% photoinitiator, 30-65% prepolymer, and 30-65% monomer by mass percentage, and more preferably include 1.5-4% photoinitiator, 35-60% prepolymer, and 37-62% monomer by mass percentage. Using the photosensitive resin composed of the above raw materials for 3D printing results in fast curing speed and high production efficiency.

[0051] In this invention, the photoinitiator can be a conventional photoinitiator in the art. Preferably, the photoinitiator is selected from at least one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (photoinitiator TPO), phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (photoinitiator 819), and isopropylthioxanthone (ITX).

[0052] In this invention, the prepolymer can be a conventional acrylate prepolymer in the art, preferably an epoxy acrylate prepolymer and / or a polyurethane acrylate prepolymer.

[0053] In this invention, the monomer can be a monomer conventional in the art, and preferably, the monomer is selected from at least one of 1,6-hexanediol diacrylate (HDDA), tripropylene glycol diacrylate (TPGDA), and trimethylolpropane triacrylate (TMPTA).

[0054] In this invention, aluminosilicate ceramic green bodies are prepared using 3D printing. Three-dimensional structural design is performed using modeling software, and aluminosilicate photosensitive resin slurry is poured into the material cylinder of a DLP photopolymerization printer for printing, resulting in the aluminosilicate ceramic green body. In this invention, "aluminosilicate ceramic green body" is a general term for these prepared green bodies. The printing method allows for the customization of complex three-dimensional structures suitable for different scenarios, without relying on molds or requiring complex post-processing of the carrier. The three-dimensional pore structure of the carrier is simple and controllable.

[0055] In this invention, preferably, three-dimensional structural design is performed using modeling software, which is selected from SolidWorks, 3DMAX, AutoCAD or Materialise Magics.

[0056] According to the present invention, preferably, the 3D printing conditions include: a photopolymerization exposure power of 0.5-5 mW / cm². 2 The first layer exposure time is 15-30s, the exposure time for other layers is 5-15s, and the thickness of a single layer photocured is 20-100μm.

[0057] In this invention, preferably, the process further includes cleaning the obtained aluminosilicate ceramic blank after printing. There are no particular limitations on the cleaning conditions, and those skilled in the art can make appropriate selections. According to a preferred embodiment of this invention, anhydrous ethanol is used for thorough cleaning.

[0058] This invention does not impose particular limitations on the size and shape of the aluminosilicate ceramic preform; those skilled in the art can make appropriate selections based on the specific application scenario of the prepared catalyst. A preferred embodiment for application in a catalytic cracking catalyst is subsequently provided, but this invention is not limited thereto.

[0059] According to the present invention, preferably, the cross-sectional dimension of the aluminosilicate ceramic blank is 0.5-15 cm. In the present invention, the cross-section of the aluminosilicate ceramic blank is a section parallel to the bottom surface, and the cross-sectional dimension is the straight-line distance obtained by connecting the two farthest endpoints of the cross-section.

[0060] In this invention, the aluminosilicate ceramic green body provides a framework for the molecular sieve catalyst. The green body has a porous structure and forms an aluminosilicate ceramic support after sintering, which enables the molecular sieve seeds in the crystallization incubation solution to grow rapidly on the support, thereby increasing the mass percentage of molecular sieve (preferably ZSM-5) in the prepared molecular sieve catalyst.

[0061] According to the present invention, preferably, the aluminosilicate ceramic support has a porous, self-supporting three-dimensional structure. The present invention does not particularly limit the porous, self-supporting three-dimensional structure; it has the conventional interpretation in the art. Specifically, "self-supporting" refers to the aluminosilicate ceramic support possessing its own strength and stiffness, and being able to maintain its shape and stability without external support. "Porous" refers to the porous structure of the main frame of the aluminosilicate ceramic support. There is no particular limitation on the distribution of the pores; it can be appropriately selected according to the specific catalyst application scenario. The distribution of the pores can be uniform, symmetrical, or non-uniform and asymmetrical. To further improve the application effect of the catalyst in catalytic cracking reactions, it is further preferred that the aluminosilicate ceramic support be a self-supporting three-dimensional structure with parallel radial and axially interconnected pore structures. Specific pore structures are as follows: Figure 1 and Figure 2 As shown.

[0062] This invention does not specifically limit the interconnecting channel structure, which has the conventional interpretation in the art. In this invention, the interconnecting channel structure refers to the vertical and horizontal channels of the aluminosilicate ceramic carrier being interconnected, providing good permeability.

[0063] According to the present invention, preferably, the sintering conditions in step (2) include: a temperature of 1100-1300℃ and a time of 5-20h. More preferably, the sintering conditions in step (2) include: a temperature of 1150-1250℃ and a time of 8-16h.

[0064] In this invention, the aluminosilicate ceramic blank is sintered in step (2). Those skilled in the art can adjust the heating rate of the sintering process as needed. Preferably, the heating rate is 0.1-10℃ / min, and more preferably 0.5-5℃ / min.

[0065] According to the present invention, preferably, the method further includes pyrolyzing the aluminosilicate ceramic green body before sintering to remove organic matter from the green body, wherein the pyrolysis conditions include: a temperature of 350-550°C and a time of 5-15 h; preferably, the pyrolysis conditions include: a temperature of 380-520°C and a time of 6-13 h.

[0066] In this invention, those skilled in the art can adjust the heating rate of the pyrolysis process as needed. Preferably, the heating rate of the pyrolysis process is 0.1-5℃ / min, and more preferably 0.5-2℃ / min.

[0067] According to the present invention, preferably, in the crystallization mother liquor, the aluminum source is calculated as Al2O3, the silicon source is calculated as SiO2, the alkali source is calculated as Na2O, and the molar ratio of SiO2:Al2O3:template agent:Na2O:H2O is 1:(0.003-0.03):(0.05-0.25):(0.05-0.3):(30-55), preferably 1:(0.005-0.025):(0.08-0.2):(0.08-0.25):(35-50).

[0068] According to the present invention, the silicon source can be a conventional silicon source in the art, and those skilled in the art can make an adaptive selection as needed, preferably silica sol and / or tetraethyl orthosilicate.

[0069] According to the present invention, the aluminum source can be a conventional aluminum source in the art, and those skilled in the art can make an adaptive selection as needed, preferably selected from at least one of aluminum sulfate, aluminum isopropoxide and aluminum trichloride.

[0070] In this invention, preferably, the alkali source can be a conventional alkali source in the art, and those skilled in the art can make an adaptive selection as needed, preferably sodium hydroxide.

[0071] In this invention, the range of types of template agents is relatively wide, and an adaptive selection can be made according to the specific type of molecular sieve to be synthesized. Preferably, the template agent is an organic amine microporous template agent known to those skilled in the art for use in the preparation of ZSM-5, preferably tetrapropylammonium hydroxide and / or tetrapropylammonium bromide.

[0072] In this invention, preferably, the use of the aforementioned silicon source, aluminum source, and template agent to provide molecular sieve seed crystals for the crystallization mother liquor helps to accelerate the growth rate of molecular sieves on the aluminosilicate ceramic support and shorten the crystallization time of the molecular sieve.

[0073] According to the present invention, preferably, the crystallization conditions in step (3) include: a crystallization temperature of 155-185℃, preferably 165-180℃, and a crystallization time of 3-10h, preferably 4-9h.

[0074] In this invention, the reaction equipment for crystallization and hydrothermal crystallization has a wide range of options, and those skilled in the art can make adaptive selections as needed. Preferably, it is carried out in a crystallization kettle. In this invention, it is preferable to open the crystallization kettle after crystallization and / or hydrothermal crystallization is completed, after the kettle has been cooled (preferably to room temperature). This preferred embodiment avoids the safety hazards that arise when opening the kettle due to the self-generated pressure inside the kettle caused by crystallization reactions at high temperatures.

[0075] In this invention, preferably, the crystallization mother liquor is crystallized under the above conditions to obtain a crystallization incubation solution, which can further improve the crystallinity of the prepared molecular sieve catalyst. The crystallization incubation solution contains molecular sieve seeds. From the perspective of crystal growth kinetics, the use of the incubation solution can significantly shorten the nucleation period of crystals on the support surface, thereby accelerating the crystallization process of molecular sieves on the support surface.

[0076] According to the present invention, preferably, in step (4), the mass ratio of the aluminosilicate ceramic support to the crystallization incubation solution is 1:6-20, for example 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, and any range between any two values, preferably 1:8-15. This preferred embodiment is more advantageous in matching the dissolution rate of silicon species on the support itself with the crystallization rate of the surface molecular sieve, obtaining a crystallized product that balances crystallinity and self-supporting structural strength.

[0077] According to the present invention, preferably, the conditions for hydrothermal crystallization include: a crystallization temperature of 155-185°C, more preferably 165-180°C, and a crystallization time of 12-40 h, more preferably 15-35 h.

[0078] In this invention, preferably, the method further includes: post-treatment of the solid product obtained by hydrothermal crystallization, the post-treatment including washing and drying. Washing can be performed using conventional methods and conditions in the art; according to some preferred embodiments of the invention, washing can be performed using deionized water.

[0079] In this invention, drying can be carried out using conventional methods and conditions in the art. According to some preferred embodiments of the invention, drying can be carried out in an oven under the following conditions: drying at 60-120°C for 2-10 hours.

[0080] According to the present invention, there are no particular limitations on the conditions for the first calcination, as long as the template agent in the solid product can be removed. Preferably, the conditions for the first calcination include: a temperature of 500-600°C and a time of 4-8 hours. There are no particular limitations on the calcination equipment, but preferably, the calcination can be carried out in a muffle furnace.

[0081] In this invention, the "first roasting", "second roasting" and "third roasting" are not limited to a specific order, but are only used to distinguish different roasting processes. The roasting conditions and roasting equipment used can be the same or different.

[0082] According to the present invention, the ammonium exchange process is not particularly limited and is a conventional ammonium exchange operation in the art. According to a preferred embodiment of the present invention, the sodium molecular sieve catalyst is placed in an ammonium salt solution. Preferably, in step (5), the conditions for the ammonium exchange include: a temperature of 60-90°C, preferably 70-80°C, and a time of 0.5-3 h, preferably 1-2 h.

[0083] According to the present invention, preferably, the ammonium exchange is performed 2-4 times.

[0084] According to the present invention, preferably, the mass ratio of the sodium-type molecular sieve catalyst to the ammonium salt solution is 1:8-20, for example 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, and any range between any two values, preferably 1:10-15. This preferred embodiment is more advantageous in replacing sodium ions in the sodium-type molecular sieve catalyst with ammonium ions to obtain a hydrogen-type molecular sieve catalyst.

[0085] In this invention, the ammonium salt is an inorganic ammonium salt known to those skilled in the art that can be used to prepare hydrogen-type molecular sieve catalysts, preferably ammonium chloride and / or ammonium sulfate.

[0086] According to the present invention, preferably, the mass fraction of ammonium salt in the ammonium salt solution is 5-30%, more preferably 10-20%.

[0087] In this invention, preferably, step (5) further includes: post-processing the solid product obtained from ammonium exchange, the post-processing including washing, drying, and a third calcination. Washing can be performed using conventional methods and conditions in the art, and according to some preferred embodiments of the invention, washing can be performed using deionized water.

[0088] In this invention, drying can be carried out using conventional methods and conditions in the art. According to some preferred embodiments of the invention, drying can be carried out in an oven under the following conditions: drying at 60-120°C for 2-10 hours.

[0089] In this invention, preferably, the conditions for the third roasting are not particularly limited, as long as the nitrogen element in the ammonium ions of the solid product can be removed in the form of ammonia gas. Preferably, the conditions for the third roasting include: a temperature of 500-600℃ and a time of 1-4 hours. The roasting equipment is not particularly limited, but preferably, the third roasting can be carried out in a muffle furnace.

[0090] According to the present invention, preferably, in step (6), the impregnation conditions include: a temperature of 20-30°C, a time of 1-5 hours, and a vacuum degree of -0.05 to -0.1 MPa. In the present invention, vacuum impregnation helps to replace hydrogen ions with nickel ions.

[0091] According to the present invention, preferably, the amount of the hydrogen-form molecular sieve catalyst and the nickel salt solution is such that the mass percentage of nickel in the obtained 3D printing molecular sieve catalyst is 0.5-10%, preferably 2-8%. The mass ratio of the hydrogen-form molecular sieve catalyst support to the nickel salt solution is 1:0.06-1.29, for example 1:0.06, 1:0.12, 1:0.25, 1:0.38, 1:0.51, 1:0.64, 1:0.77, 1:0.89, 1:1.02, 1:1.15, 1:1.28, 1:1.29, and any range between any two values, preferably 1:0.25-1.02. This preferred embodiment is more conducive to replacing hydrogen ions in the hydrogen-form molecular sieve catalyst with nickel ions, obtaining a nickel-supported 3D printing molecular sieve catalyst.

[0092] According to the present invention, preferably, the nickel salt is an organic nickel salt and / or an inorganic nickel salt, and is preferably selected from at least one of nickel nitrate, nickel chloride and nickel acetate.

[0093] According to the present invention, preferably, the mass fraction of nickel salt in the nickel salt solution is 5-20%, more preferably 10-15%.

[0094] In this invention, the impregnation can be carried out using conventional impregnation equipment in the art. According to some preferred embodiments of the invention, the impregnation can be carried out in a rotary evaporator and / or a Schlenk tube.

[0095] This invention also includes drying the impregnated solid product. The drying can be performed using conventional methods and conditions in the art. According to some preferred embodiments of the invention, the drying can be carried out in an oven under the following conditions: 60-120°C for 2-10 hours.

[0096] In this invention, there are no particular limitations on the conditions for the second calcination, as long as the nickel ions in the solid product can form stable +2 or +3 valence nickel ions. Preferably, the conditions for the second calcination include: a temperature of 400-600℃ and a time of 1-4 hours. There are no particular limitations on the calcination equipment, but preferably, the second calcination can be carried out in a muffle furnace.

[0097] According to the present invention, preferably, the ZSM-5 molecular sieve content in the 3D printing molecular sieve catalyst prepared by this method is 20-55%, and more preferably 35-52%.

[0098] In this invention, the mass percentage of molecular sieve in the molecular sieve catalyst is expressed by relative crystallinity. Referring to ASTM D3906-03 standard, commercial ZSM-5 molecular sieve (Tianjin Nanhua Catalyst Co., Ltd., Nankai University Catalyst Plant Na-type ZSM-5 molecular sieve, Si / A ratio 25) is used as the standard, and the crystallinity of commercial ZSM-5 is defined as 100%. The ratio of the area of ​​the characteristic peak between 22.0-25.0° at the 2θ angle in the XRD pattern of the crystallized product to the area of ​​the characteristic peak of the standard molecular sieve is defined as the relative crystallinity. Experimental instrument: Siemens D5005 X-ray diffractometer. Experimental conditions: Cu target, Kα radiation, solid-state detector, tube voltage 40kV, tube current 40mA, step scan, step size 0.02°, pre-set time 2s, scan range 5°-70°.

[0099] The second aspect of the present invention provides a 3D-printed molecular sieve catalyst prepared by the preparation method described in the first aspect.

[0100] According to the present invention, preferably, the 3D printing molecular sieve catalyst comprises ZSM-5 molecular sieve with a mass percentage of 20-55%, and more preferably, the 3D printing molecular sieve catalyst comprises ZSM-5 molecular sieve with a mass percentage of 35-52%.

[0101] According to the present invention, preferably, the 3D printing molecular sieve catalyst comprises 0.5-10% nickel by mass, and more preferably, the 3D printing molecular sieve catalyst comprises 2-8% nickel by mass.

[0102] In this invention, the mass percentage of nickel in the 3D printed molecular sieve catalyst was obtained by inductively coupled plasma atomic emission spectrometry (ICP-5110, Agilent Technologies).

[0103] According to the present invention, preferably, the ZSM-5 molecular sieve is distributed on the surface of the nickel-supported 3D printed molecular sieve catalyst and exists in the form of micron-sized particle aggregates. Preferably, the average particle size of the micron-sized particles is 1-5 microns, more preferably 1.5-4 microns.

[0104] In this invention, the average particle size of the ZSM-5 molecular sieve micron-sized particles of the 3D-printed molecular sieve catalyst was measured using a scanning electron microscope (Hitachi S-4800). The average value was obtained by randomly measuring the size of 20 molecular sieve crystals using Nano Measurer software. During the measurement process, the size of a single molecular sieve crystal was defined as the straight-line distance connecting the two furthest endpoints of the particle in the electron micrograph.

[0105] In this invention, preferably, the metallic nickel is distributed on the outer surface and pore openings of the ZSM-5 molecular sieve and exists in the form of nanoparticles. The average particle size of the metallic nickel particles is 10-100 nanometers, such as 10 nanometers, 15 nanometers, 20 nanometers, 30 nanometers, 40 nanometers, 50 nanometers, 60 nanometers, 70 nanometers, 80 nanometers, 90 nanometers, 100 nanometers, and any range between any two values, more preferably 15-50 nanometers.

[0106] In this invention, the average particle size of the nickel particles in the 3D-printed molecular sieve catalyst was measured using a transmission electron microscope (Hitachi HT-7800). The average size of 20 randomly selected nickel particles was obtained using NanoMeasurer software. During the measurement, the size of a single nickel particle was defined as the straight-line distance connecting the two furthest endpoints of the particle in the electron microscope image.

[0107] According to the present invention, preferably, the micropore volume of the catalyst is 0.04-0.1 cm. 3 / g, preferably 0.05-0.09cm 3 / g; mesopore volume is 0.04-0.09cm³ 3 / g, preferably 0.05-0.08cm 3 / g.

[0108] In this invention, the micropore volume and mesopore volume of the molecular sieve catalyst were measured using the low-temperature nitrogen adsorption capacity method. The experimental instrument was a Micromeritics ASAP2400 static nitrogen adsorption instrument. Experimental conditions: The sample was degassed under vacuum at 1.33 Pa and 300 °C for 4 hours, then contacted with liquid nitrogen at 77 K for isothermal adsorption and desorption. Adsorption and desorption isotherms were measured, and the micropore volume and mesopore volume were calculated using the BET formula.

[0109] In this invention, the 3D printed molecular sieve catalyst has a high molecular sieve content and high structural precision. Furthermore, the ZSM-5 molecular sieve is directly exposed on the outer surface of the support through in-situ growth, which has the advantage of high accessibility of the active center.

[0110] In this invention, transmission electron microscopy revealed that the nickel metal in the 3D-printed molecular sieve catalyst is mainly located at the pore openings of the molecular sieve (microporous aluminosilicate crystal) and is also directly exposed on the outer surface of the molecular sieve, giving it the advantage of high accessibility of the metal sites.

[0111] The third aspect of this invention provides the application of a 3D-printed molecular sieve catalyst prepared by the method described in the first aspect or the 3D-printed molecular sieve catalyst described in the second aspect in a catalytic cracking reaction.

[0112] In this invention, preferably, the reaction conditions for the catalytic cracking reaction are: a reaction pressure of 0.09-0.3 MPa, a reaction temperature of 450-600°C, and a feed weight hourly space velocity of 20-100 h⁻¹. -1 .

[0113] In this invention, there are no particular limitations on the reaction apparatus for the catalytic cracking reaction. Those skilled in the art can make appropriate selections based on the application scenario of the molecular sieve catalyst. According to a preferred embodiment of this invention, the catalytic cracking reaction can be carried out in a fixed-bed reactor.

[0114] The molecular sieve catalyst prepared in this invention has high catalytic activity and the advantage of reducing bed pressure drop, and can be widely used in catalytic cracking reactions.

[0115] According to a particularly preferred embodiment of the present invention, a method for preparing a 3D-printed molecular sieve catalyst includes the following steps:

[0116] (1) Provide an aluminosilicate photosensitive resin slurry containing aluminosilicate and photosensitive resin, and then perform 3D printing to obtain an aluminosilicate ceramic blank;

[0117] (2) The aluminosilicate ceramic blank is sintered to obtain an aluminosilicate ceramic carrier;

[0118] (3) Crystallize the crystallization mother liquor containing silicon source, aluminum source, template agent, alkali source and water to obtain crystallization incubation solution;

[0119] (4) The aluminosilicate ceramic support is hydrothermally crystallized in a crystallization incubation solution, and then the solid product obtained by hydrothermal crystallization is first calcined to obtain a sodium-type molecular sieve catalyst.

[0120] (5) The sodium-type molecular sieve catalyst is subjected to ammonium exchange to obtain a hydrogen-type molecular sieve catalyst;

[0121] (6) The hydrogen-type molecular sieve catalyst was impregnated with a nickel salt solution, and then the solid product obtained by impregnation was calcined a second time to obtain a 3D printed molecular sieve catalyst.

[0122] In the crystallization mother liquor, the aluminum source is calculated as Al2O3, the silicon source as SiO2, and the alkali source as Na2O. The molar ratio of SiO2:Al2O3:template agent:Na2O:H2O is 1:(0.005-0.025):(0.08-0.2):(0.08-0.25):(35-50).

[0123] The crystallization temperature is 165-180℃, and the crystallization time is 4-9 hours.

[0124] The amount of hydrogen-type molecular sieve catalyst and the nickel salt solution used is such that the mass percentage of nickel in the prepared 3D printed molecular sieve catalyst is 2-8%.

[0125] The present invention will be described in detail below through examples and comparative examples. Unless otherwise specified, the reagents and materials used in the following examples and comparative examples are commercially available, and the room temperature is 25°C.

[0126] The ball milling was carried out using a Juchuang Environmental Protection Vertical Planetary Ball Mill (model JC-QM-0.4);

[0127] The three-dimensional model was created using Solidworks software.

[0128] The 3D printing was completed using a recessed DLP-3D printer (model SU136A or SU-100A) from Foshan Guanglei Intelligent Manufacturing Co., Ltd. (light source wavelength: 405nm);

[0129] The test methods and conditions for the molecular sieve catalyst, including its mass percentage content, surface morphology, average particle size, pore structure, nickel mass percentage content, and particle size, are described in the aforementioned specification and will not be repeated here.

[0130] Example 1

[0131] (1) Preparation of aluminosilicate ceramic green bodies:

[0132] (1-1) Using diatomaceous earth as the silicon-based powder and metakaolin as the auxiliary powder, the silicon-based powder was mixed with 60% by mass (on a dry basis) and the auxiliary powder was 40% by mass (on a dry basis) to obtain aluminosilicate with a D90 particle size of 8 μm.

[0133] (1-2) Using 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO) as a photoinitiator, polyurethane acrylate prepolymer as a prepolymer, and 1,6-hexanediol diacrylate (HDDA) as a monomer, the photoinitiator was mixed with 4% of the prepolymer, 35% of the prepolymer, and 61% of the monomer to obtain a photosensitive resin.

[0134] (1-3) Aluminosilicate and photosensitive resin were mixed at a mass ratio of 0.65:1 and ball-milled for 14 hours (280 rpm) to obtain aluminosilicate photosensitive resin slurry;

[0135] (1-4) Perform three-dimensional structural design, import the three-dimensional model file into the 3D printing equipment, pour the aluminosilicate photosensitive resin slurry into the DLP photopolymerization printer's ink tank for printing, and set the printing parameters as follows: exposure power 1mW / cm². 2 The exposure time is 10 seconds (20 seconds for the first layer). After printing, the obtained aluminosilicate ceramic green body is thoroughly cleaned in anhydrous ethanol. The cross-sectional diameter of the aluminosilicate ceramic green body is 1.5 cm, the height is 1.43 cm, and the spacing between different strips on the same horizontal plane is 0.08 cm.

[0136] (2) The formed aluminosilicate ceramic blank is dried and then pyrolyzed and sintered. The specific pyrolysis and sintering conditions are: heating from room temperature to 450℃ at a heating rate of 0.5℃ / min and holding for 8h; heating from 450℃ to 1200℃ at a heating rate of 3℃ / min and holding for 15h to obtain the aluminosilicate ceramic carrier.

[0137] (3) Using silica sol (40wt% SiO2, Qingdao Junqiang New Materials Co., Ltd.) and aluminum sulfate (99wt%, Innochem) as silicon and aluminum sources respectively, and tetrapropylammonium hydroxide (TPAOH, 25wt%, Innochem) as template agent, the silicon source, aluminum source, template agent and sodium hydroxide were added to water and mixed to obtain crystallization mother liquor. The molar ratio of each raw material, namely SiO2:Al2O3:template agent:Na2O:H2O, was 1:0.025:0.1:0.25:35. The above mixture was crystallized at 165℃ for 9 hours to obtain crystallization incubation solution.

[0138] (4) The aluminosilicate ceramic support was placed in a crystallization incubation solution with a mass ratio of support to crystallization incubation solution of 1:13. The mixture of support and incubation solution was hydrothermally crystallized at 170°C for 30 hours. After hydrothermal crystallization, the hydrothermal crystallization product was cooled, separated, washed, dried at 100°C for 4 hours, and calcined at 550°C for 5 hours to obtain a sodium-type molecular sieve catalyst.

[0139] (5) The sodium-type molecular sieve catalyst was placed in an ammonium salt solution for ammonium exchange. The mass ratio of the sodium-type molecular sieve catalyst to the ammonium salt solution was 1:10. The ammonium salt was ammonium chloride, and the mass fraction of ammonium chloride in the ammonium salt solution was 10%. The ammonium exchange temperature was 80°C, the reaction time was 1 hour, and the exchange was repeated 3 times. After the ammonium exchange was completed, the obtained solid product was dried at 100°C for 4 hours and calcined at 550°C for 2 hours to obtain the hydrogen-type molecular sieve catalyst.

[0140] (6) The hydrogen-form molecular sieve catalyst was impregnated in a nickel salt solution, wherein the mass ratio of the hydrogen-form molecular sieve catalyst to the nickel salt solution was 1:0.64; the nickel salt was nickel acetate, and the mass fraction of the nickel salt in the solution was 10%. The impregnation conditions were: impregnation in a Schlenk tube under vacuum at 25°C for 3 hours, with a vacuum degree of -0.1 MPa. The solid product obtained after impregnation was then dried at 100°C for 5 hours and calcined at 550°C for 3 hours to obtain the 3D-printed molecular sieve catalyst.

[0141] Figure 1 The diagram shows the three-dimensional model structure established in Example 1. The three-dimensional structure is designed using modeling software, and the structural shape of the molecular sieve catalyst can be selected according to actual needs. Figure 2 The image shows a 3D-printed molecular sieve catalyst prepared in Example 1. The molecular sieve catalyst obtained by 3D printing achieves high-precision, digital design and better regularity.

[0142] The XRD pattern of the catalyst prepared in Example 1 is shown below. Figure 3 As shown, from Figure 3 It can be seen that the synthesized 3D printed molecular sieve catalyst has the characteristic diffraction peaks of ZSM-5 molecular sieve, with obvious five-finger diffraction peaks appearing at 2θ in the range of 22.0-25.0°. The surface nickel dispersion is good, and no diffraction peaks of nickel oxide or nickel trioxide were observed. Figure 4 , Figure 5 The images are scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the catalyst from Example 1, respectively. Figure 4 As can be seen, the outer surface of the catalyst is densely covered with ZSM-5 molecular sieve particles, mainly existing in the form of micron-sized aggregates, with an average particle size of 1.8 micrometers. The ZSM-5 molecular sieves are directly exposed to the outer surface of the support through in-situ growth, offering the advantage of high accessibility of the active centers. Figure 5 The presence of nickel metal species on the surface can be observed in the transmission electron microscope image. Figure 5 The part marked by the middle circle is the nickel metal on the surface of the molecular sieve. Figure 6 EDS-Mapping elemental distribution of 3D-printed molecular sieve catalysts. Figure 6The bright spot on the right half shows the distribution of nickel metal on the surface of the molecular sieve, indicating that the nickel metal species on the surface are well dispersed.

[0143] Figure 7 These are the isothermal adsorption curves of the 3D-printed molecular sieve catalyst prepared in Example 1. Figure 8 This is the pore distribution curve of the 3D-printed molecular sieve catalyst prepared in Example 1, as shown below. Figure 7 , Figure 8 As shown, the 3D-printed molecular sieve catalyst exhibits hysteresis loops in the adsorption isotherm, and mesopores are observed in the sample from the pore size distribution curve.

[0144] Comparative Example 1

[0145] The 3D printed molecular sieve catalyst was prepared according to the method of Example 1. The difference is that in step (1), silicon-based powder was not used, and all auxiliary powder (kaolin) was used to prepare aluminosilicate to obtain the 3D printed molecular sieve catalyst sample.

[0146] Comparative Example 2

[0147] The 3D-printed molecular sieve catalyst was prepared according to the method of Example 1, except that in step (6), the same mass of ferric chloride was used instead of nickel chloride to prepare an iron-supported 3D-printed molecular sieve catalyst sample.

[0148] Comparative Example 3

[0149] Nickel-supported hydrogen-form ZSM-5 powder (Tianjin Nanhua Catalyst Co., Ltd., Nankai University Catalyst Plant Na-type ZSM-5 molecular sieve, silicon-to-aluminum ratio 25) was compressed into tablets to prepare 40-60 mesh molecular sieve particles, which were directly used for the evaluation of catalytic cracking of alkane molecules. Except for the catalyst, the other reaction evaluation conditions were the same as in Example 1, and this was referred to as a pure molecular sieve-nickel catalyst.

[0150] Comparative Example 4

[0151] The 3D printed molecular sieve catalyst was prepared according to the method of Example 1, except that in step (3), nickel acetate was directly added to the crystallization mother liquor, and step (6) was not performed, and the 3D printed molecular sieve catalyst sample was obtained.

[0152] Example 2

[0153] (1) Preparation of aluminosilicate ceramic green bodies:

[0154] (1-1) Using silica as silicon-based powder and bentonite as auxiliary powder, the silica-based powder was mixed with 40% by mass (on a dry basis) and 60% by mass (on a dry basis) to obtain aluminosilicate with a D90 particle size of 23.7 μm.

[0155] (1-2) Using isopropylthioxanthone (ITX) as a photoinitiator, polyurethane acrylate prepolymer as a prepolymer, and trimethylolpropane triacrylate (TMPTA) as a monomer, the photoinitiator was mixed with 1.5% of the photoinitiator, 60% of the prepolymer, and 38.5% of the monomer to obtain a photosensitive resin.

[0156] (1-3) Aluminosilicate and photosensitive resin were mixed at a mass ratio of 0.85:1 and ball-milled for 8 hours (400 rpm) to obtain aluminosilicate photosensitive resin slurry;

[0157] (1-4) Perform three-dimensional structural design, import the three-dimensional model file into the 3D printing equipment, and perform 3D printing according to the three-dimensional model in Example 1. Pour the aluminosilicate photosensitive resin slurry into the material cylinder of the DLP photopolymer printer for printing. The printing parameters are: exposure power 1mW / cm 2 Exposure time is 10s (exposure time for the first layer is 20s); after printing, the obtained aluminosilicate ceramic blank is thoroughly cleaned in anhydrous ethanol.

[0158] (2) The formed aluminosilicate ceramic blank is dried and then pyrolyzed and sintered. The specific conditions are: heating from room temperature to 500℃ at a heating rate of 0.5℃ / min and holding for 6h; heating from 500℃ to 1200℃ at a heating rate of 3℃ / min and holding for 10h to obtain the aluminosilicate ceramic carrier.

[0159] (3) Silica sol (40wt% SiO2, Qingdao Junqiang New Materials Co., Ltd.) and aluminum sulfate (99wt%, Innochem) were used as the silicon source and aluminum source, respectively, and tetrapropylammonium hydroxide (TPAOH, 25wt%, Innochem) was used as the template agent. The silicon source, aluminum source, template agent, and sodium hydroxide were added to water and mixed to obtain a crystallization mother liquor. The molar ratio of each raw material, namely SiO2:Al2O3:template agent:Na2O:H2O, was 1:0.005:0.15:0.1:45. The above mixture was crystallized at 180℃ for 4.5 hours to obtain a crystallization incubation solution.

[0160] (4) The aluminosilicate ceramic support was placed in a crystallization incubation solution with a mass ratio of support to crystallization incubation solution of 1:6. The mixture of support and crystallization incubation solution was hydrothermally crystallized at 180°C for 15 hours. After crystallization, the crystallization product was cooled, separated, washed, dried at 100°C for 4 hours, and calcined at 550°C for 5 hours to obtain a 3D printed molecular sieve catalyst sample.

[0161] (5) The sodium-type molecular sieve catalyst was placed in an ammonium salt solution for ammonium exchange. The mass ratio of the sodium-type molecular sieve catalyst support to the ammonium salt solution was 1:10. The ammonium salt was ammonium chloride, and the mass fraction of ammonium chloride in the ammonium salt solution was 10%. The ammonium exchange temperature was 80°C, the reaction time was 1 hour, and the exchange was repeated 3 times. After the ammonium exchange was completed, the solid product obtained after the ammonium exchange was dried at 100°C for 4 hours and calcined at 550°C for 2 hours to obtain the hydrogen-type molecular sieve catalyst.

[0162] (6) The hydrogen-form molecular sieve catalyst is impregnated in a nickel salt solution, wherein the mass ratio of the hydrogen-form molecular sieve catalyst support to the nickel salt solution is 1:0.77, the nickel salt is nickel acetate, and the mass fraction of the nickel salt solution is 13.5%. The impregnation conditions include: impregnation in a rotary evaporator, wherein the impregnation conditions are: impregnation under vacuum at 25°C for 5 hours, and the vacuum degree is -0.09 MPa. Then, the solid product obtained after impregnation is dried and calcined. The drying conditions include: temperature at 110°C for 4 hours, and the calcination conditions include: temperature at 600°C for 2 hours.

[0163] Example 3

[0164] The 3D printed molecular sieve catalyst was prepared according to the method of Example 1, except that the mass fraction of the nickel salt in step (6) was 5%, and the 3D printed molecular sieve catalyst sample was obtained.

[0165] Example 4

[0166] The 3D-printed molecular sieve catalyst was prepared according to the method of Example 1, except that the mass ratio of the hydrogen-type molecular sieve catalyst to the nickel salt solution in step (6) was 1:1.28, and the 3D-printed molecular sieve catalyst sample was obtained.

[0167] Example 5

[0168] The 3D-printed molecular sieve catalyst was prepared according to the method in Example 1, except that the hydrogen-type molecular sieve catalyst was not impregnated under room temperature and negative pressure conditions, but the nickel salt solution was directly heated and evaporated to prepare the 3D-printed molecular sieve catalyst sample.

[0169] Example 6

[0170] The 3D printed molecular sieve catalyst was prepared according to the method of Example 1, except that the nickel salt in step (6) was changed to nickel sulfate of equal mass fraction to obtain the 3D printed molecular sieve catalyst.

[0171] Example 7

[0172] (1) Preparation of aluminosilicate ceramic green bodies:

[0173] (1-1) Using silica as the silicon-based powder and kaolin as the auxiliary powder, the silica-based powder and the auxiliary powder were mixed at a mass fraction of 50% (on a dry basis) to obtain aluminosilicate with a D90 particle size of 12.5 μm.

[0174] (1-2) Using phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (819) as a photoinitiator, polyurethane acrylate prepolymer as a prepolymer, and tripropylene glycol diacrylate (TPGDA) as a monomer, the photoinitiator was mixed with 3%, the prepolymer with 45%, and the monomer with 52% to obtain a photosensitive resin.

[0175] (1-3) Aluminosilicate and photosensitive resin were mixed at a mass ratio of 0.72:1 and ball-milled for 10 hours (350 rpm) to obtain aluminosilicate photosensitive resin slurry;

[0176] (1-4) Perform three-dimensional structural design, import the three-dimensional model file into the 3D printing equipment, and perform 3D printing according to the three-dimensional model in Example 1. Pour the aluminosilicate photosensitive resin slurry into the material cylinder of the DLP photopolymer printer for printing. The printing parameters are: exposure power 1mW / cm 2 Exposure time is 10s (exposure time for the first layer is 20s); after printing, the obtained aluminosilicate ceramic blank is thoroughly cleaned in anhydrous ethanol.

[0177] (2) The formed aluminosilicate ceramic blank is dried and then pyrolyzed and sintered. The specific pyrolysis and sintering conditions are: heating from room temperature to 500℃ at a heating rate of 0.5℃ / min and holding for 6h; heating from 500℃ to 1200℃ at a heating rate of 3℃ / min and holding for 10h to obtain the aluminosilicate ceramic carrier.

[0178] (3) Using silica sol (40wt% SiO2, Qingdao Junqiang New Materials Co., Ltd.) and aluminum sulfate (99wt%, Innochem) as silicon and aluminum sources respectively, and tetrapropylammonium hydroxide (TPAOH, 25wt%, Innochem) as template agent, the silicon source, aluminum source, template agent and sodium hydroxide were added to water and mixed to obtain crystallization mother liquor. The molar ratio of each raw material, namely SiO2:Al2O3:template agent:Na2O:H2O, was 1:0.01:0.06:0.2:40. The above mixture was crystallized at 170℃ for 7 hours to obtain crystallization incubation solution.

[0179] (4) The aluminosilicate ceramic support was placed in a crystallization incubation solution with a mass ratio of support to crystallization incubation solution of 1:10. The mixture of support and crystallization incubation solution was hydrothermally crystallized at 170°C for 24 hours. After hydrothermal crystallization, the hydrothermal crystallization product was cooled, separated, washed, dried at 100°C for 4 hours, and calcined at 550°C for 5 hours to obtain the 3D printed molecular sieve catalyst.

[0180] (5) The sodium-type molecular sieve catalyst was placed in an ammonium salt solution for ammonium exchange, wherein the mass ratio of the sodium-type molecular sieve catalyst to the ammonium salt solution was 1:10, the ammonium salt was ammonium chloride, the mass fraction of ammonium chloride in the ammonium salt solution was 10%, the ammonium exchange temperature was 80℃, the reaction time was 1h, and the exchange was repeated 3 times. After the ammonium exchange was completed, the solid product obtained after the ammonium exchange was dried at 100℃ for 4 hours and calcined at 550℃ for 2 hours to obtain the hydrogen-type molecular sieve catalyst.

[0181] (6) The hydrogen-form molecular sieve catalyst was impregnated in a nickel salt solution, wherein the mass ratio of the hydrogen-form molecular sieve catalyst to the nickel salt solution was 1:0.51, and the nickel salt was nickel acetate with a mass fraction of 11.5%. The impregnation conditions were as follows: impregnation was carried out in a Schlenk tube under vacuum at 25°C for 4 hours at a vacuum degree of -0.08 MPa. The solid product obtained after impregnation was then dried at 90°C for 6 hours and calcined at 500°C for 4 hours.

[0182] Test Example 1

[0183] The ZSM-5 mass percentage, molecular sieve particle size, micropore volume, and mesopore volume in the 3D printed molecular sieve catalysts prepared in the examples and comparative examples are shown in Table 1.

[0184] Table 1. Properties of the molecular sieve samples prepared in the examples and comparative examples.

[0185]

[0186] Test Example 2

[0187] The properties of metallic nickel in the molecular sieve catalysts prepared in the test examples and comparative examples are shown in Table 2.

[0188] Table 2

[0189]

[0190]

[0191] As can be seen from the results in Table 2, the nickel particles in the 3D printed molecular sieve catalyst prepared in the examples are small in size, and the particle size of the nickel particles is larger than that of the molecular sieve micropores, indicating that the nickel particles did not enter the interior of the molecular sieve framework and did not damage the molecular sieve pore framework.

[0192] Test Example 3: Catalytic Activity Test of 3D Printed Molecular Sieves Catalyst

[0193] The 3D-printed molecular sieve catalyst was placed in a fixed-bed reactor at a reaction pressure of 0.15 MPa, a reaction temperature of 500 °C, and a feed weight hourly space velocity (WHSV) of 50 h⁻¹. -1 After the reaction, the liquid phase was collected by cold bath, and the gaseous product was collected by water displacement. The liquid phase product was analyzed by Agilent 7890B (HP-PONA column) chromatography, and the gaseous product was analyzed by Agilent 6890 chromatography.

[0194] The conversion rate of n-octane is calculated according to the following formula: Conversion rate = 1 - (mass of n-octane in liquid product / mass of n-octane feedstock), and the results are shown in Table 3.

[0195] The BTX mass fraction in the liquid phase product refers to the sum of the mass fractions of benzene (B), toluene (T), and xylene (X) in all the liquid phase products.

[0196] Table 3

[0197]

[0198]

[0199] As can be seen from the results in Table 3, the catalytic cracking reaction using the 3D-printed molecular sieve catalyst prepared in the examples showed a significantly higher conversion rate than the comparative example under conditions of comparable crystallinity. Furthermore, due to the dehydrogenation effect of metallic nickel, the liquid phase products obtained in the examples had higher mass fractions of high-value products benzene (B), toluene (T), and xylene (X), indicating that the catalyst in the examples is more conducive to obtaining high-value products and can be used for highly selective aromatics production.

[0200] The catalytic cracking reaction using the pure molecular sieve-nickel catalyst of Comparative Example 3 showed a significantly lower conversion rate than that of the Example under the same reaction conditions.

[0201] Compared with traditional molecular sieve powders, the 3D printing ZSM-5 molecular sieve catalyst prepared by this invention is easy to separate and recover from the synthesis solution, the synthesis process has low equipment requirements, and it has high catalytic activity. Therefore, this invention has good application prospects.

[0202] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a 3D-printed molecular sieve catalyst, characterized in that, The method includes the following steps: (1) Provide an aluminosilicate photosensitive resin slurry containing aluminosilicate and photosensitive resin, and then perform 3D printing to obtain an aluminosilicate ceramic blank; (2) The aluminosilicate ceramic blank is sintered to obtain an aluminosilicate ceramic carrier; (3) Crystallize the crystallization mother liquor containing silicon source, aluminum source, template agent, alkali source and water to obtain crystallization incubation solution; (4) The aluminosilicate ceramic support is subjected to hydrothermal crystallization in a crystallization incubation solution, and then the solid product obtained by hydrothermal crystallization is subjected to a first calcination to obtain a sodium-type molecular sieve catalyst. (5) The sodium-type molecular sieve catalyst is subjected to ammonium exchange to obtain a hydrogen-type molecular sieve catalyst; (6) The hydrogen-type molecular sieve catalyst was impregnated with a nickel salt solution, and then the solid product obtained by impregnation was subjected to a second calcination to obtain a 3D printed molecular sieve catalyst. The aluminosilicate comprises silicon-based powder and auxiliary powder, wherein the mass percentage of silicon-based powder is 35-65% on a dry basis, and the mass percentage of auxiliary powder is 35-65% on a dry basis.

2. The method according to claim 1, wherein, The aluminosilicate comprises silicon-based powder and auxiliary powder, wherein the mass percentage of silicon-based powder is 45-60% on a dry basis, and the mass percentage of auxiliary powder is 40-55% on a dry basis.

3. The method according to claim 1, wherein, The silicon-based powder is selected from at least one of silicon dioxide, fumed silica and diatomaceous earth; And / or, the auxiliary powder is selected from at least one of kaolin, metakaolin, bentonite and montmorillonite.

4. The method according to claim 1, wherein, The mass ratio of the aluminosilicate to the photosensitive resin is 0.5-1:

1.

5. The method according to claim 4, wherein, The mass ratio of the aluminosilicate to the photosensitive resin is 0.6-0.9:

1.

6. The method according to claim 1, wherein, The raw materials of the photosensitive resin include 1-5% photoinitiator, 30-65% prepolymer, and 30-65% monomer by mass percentage.

7. The method according to claim 6, wherein, The raw materials of the photosensitive resin include 1.5-4% photoinitiator, 35-60% prepolymer, and 37-62% monomer by mass percentage.

8. The method according to claim 6, wherein, The photoinitiator is selected from at least one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and isopropylthioxanthrone; And / or, the prepolymer is an epoxy acrylate prepolymer and / or a polyurethane acrylate prepolymer; And / or, the monomer is selected from at least one of 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, and trimethylolpropane triacrylate.

9. The method according to claim 1, wherein, The conditions for 3D printing include: photopolymerization exposure power of 0.5-5mW / cm². 2 The first layer exposure time is 15-30s, the exposure time for other layers is 5-15s, and the thickness of a single layer photocured is 20-100μm.

10. The method according to claim 1, wherein, The cross-sectional dimensions of the aluminosilicate ceramic preform are 0.5-15 cm. And / or, the aluminosilicate ceramic carrier has a porous, self-supporting three-dimensional structure.

11. The method according to claim 10, wherein, The aluminosilicate ceramic carrier has a self-supporting three-dimensional structure with parallel radial and axial interconnected channels.

12. The method according to claim 1, wherein, The sintering conditions in step (2) include: a temperature of 1100-1300℃ and a time of 5-20h.

13. The method according to claim 1, wherein, The method further includes pyrolyzing the aluminosilicate ceramic green body before sintering, wherein the pyrolysis conditions include a temperature of 350-550℃ and a time of 5-15h.

14. The method according to claim 1, wherein, In the crystallization mother liquor, the aluminum source is calculated as Al2O3, the silicon source is calculated as SiO2, the alkali source is calculated as Na2O, and the molar ratio of SiO2:Al2O3:template agent:Na2O:H2O is 1:(0.003-0.03):(0.05-0.25):(0.05-0.3):(30-55).

15. The method according to claim 14, wherein, In the crystallization mother liquor, the aluminum source is calculated as Al2O3, the silicon source is calculated as SiO2, the alkali source is calculated as Na2O, and the molar ratio of SiO2:Al2O3:template agent:Na2O:H2O is 1:(0.005-0.025):(0.08-0.2):(0.08-0.25):(35-50).

16. The method according to claim 1, wherein, The silicon source is silica sol and / or tetraethyl orthosilicate; and / or, the aluminum source is selected from at least one of aluminum sulfate, aluminum isopropoxide and aluminum trichloride; and / or, the template agent is an organic amine microporous template agent for preparing ZSM-5.

17. The method according to claim 1, wherein, The crystallization conditions in step (3) include: a crystallization temperature of 155-185℃ and a crystallization time of 3-10h.

18. The method according to claim 17, wherein, The crystallization conditions in step (3) include: a crystallization temperature of 165-180℃ and a crystallization time of 4-9h.

19. The method according to claim 1, wherein, In step (4), the mass ratio of the aluminosilicate ceramic carrier to the crystallization incubation solution is 1:6-20 based on their total mass. And / or, the conditions for hydrothermal crystallization include: a crystallization temperature of 155-185℃ and a crystallization time of 12-40h.

20. The method according to claim 19, wherein, In step (4), the mass ratio of the aluminosilicate ceramic carrier to the crystallization incubation solution is 1:8-15 based on their total mass. And / or, the conditions for hydrothermal crystallization include: a crystallization temperature of 165-180℃ and a crystallization time of 15-35h.

21. The method according to claim 1, wherein, The conditions for the first roasting include: a temperature of 500-600℃ and a time of 4-8 hours.

22. The method according to claim 1, wherein, In step (5), the conditions for ammonium exchange include: a temperature of 60-90℃ and a time of 0.5-3h; And / or, the number of ammonium exchanges is 2-4 times.

23. The method according to claim 22, wherein, In step (5), the conditions for ammonium exchange include: a temperature of 70-80℃ and a time of 1-2h.

24. The method according to claim 1, wherein, The mass ratio of the sodium-type molecular sieve catalyst to the ammonium salt solution is 1:8-20; And / or, the ammonium salt is ammonium chloride and / or ammonium sulfate; And / or, the mass fraction of ammonium salt in the ammonium salt solution is 5-30%.

25. The method according to claim 24, wherein, The mass ratio of the sodium-type molecular sieve catalyst to the ammonium salt solution is 1:10-15; And / or, the mass fraction of ammonium salt in the ammonium salt solution is 10-20%.

26. The method according to claim 1, wherein, In step (6), the impregnation conditions include: a temperature of 20-30°C, a time of 1-5 hours, and a vacuum degree of -0.05 to -0.1 MPa.

27. The method according to claim 1, wherein, The mass ratio of the hydrogen-form molecular sieve catalyst support to the nickel salt solution is 1:0.06-1.29; And / or, the amount of the hydrogen-type molecular sieve catalyst and the nickel salt solution is such that the mass percentage of nickel in the prepared 3D-printed molecular sieve catalyst is 0.5-10%.

28. The method according to claim 27, wherein, The mass ratio of the hydrogen-form molecular sieve catalyst support to the nickel salt solution is 1:0.25-1.02; And / or, the amount of the hydrogen-type molecular sieve catalyst and the nickel salt solution is such that the mass percentage of nickel in the prepared 3D-printed molecular sieve catalyst is 2-8%.

29. The method according to claim 27, wherein, The metallic nickel salt is an organic nickel salt and / or an inorganic nickel salt; And / or, the mass fraction of the nickel salt in the nickel salt solution is 5-20%.

30. The method according to claim 29, wherein, The nickel salt is selected from at least one of nickel nitrate, nickel chloride, and nickel acetate; And / or, the mass fraction of the nickel salt in the nickel salt solution is 10-15%.

31. The 3D printing molecular sieve catalyst prepared by the preparation method according to any one of claims 1-30.

32. The 3D-printed molecular sieve catalyst according to claim 31, wherein, The 3D printed molecular sieve catalyst includes ZSM-5 molecular sieve with a mass percentage of 20-55%.

33. The 3D-printed molecular sieve catalyst according to claim 31, wherein, ZSM-5 molecular sieves are distributed on the surface of the 3D printed molecular sieve catalyst and exist in the form of micron-sized particle aggregates.

34. The 3D-printed molecular sieve catalyst according to claim 33, wherein, The average particle size of the micron-sized particles is 1-5 micrometers.

35. The 3D-printed molecular sieve catalyst according to claim 31, wherein, The nickel content in the 3D-printed molecular sieve catalyst is 0.5-10% by mass. And / or, the micropore volume of the 3D-printed molecular sieve catalyst is 0.04-0.1 cm³. 3 / g; mesopore volume is 0.04-0.09cm³ 3 / g.

36. The 3D-printed molecular sieve catalyst according to claim 35, wherein, The nickel content in the 3D printed molecular sieve catalyst is 2-8% by mass.

37. The application of the 3D-printed molecular sieve catalyst prepared by the method of any one of claims 1-30 or the 3D-printed molecular sieve catalyst of any one of claims 31-36 in catalytic cracking reaction.

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