Double-hole catalyst, preparation method thereof and application of double-hole catalyst in low-carbon olefin production reaction from waste plastics

Abstract

This invention relates to the fields of catalysts and polymer material recycling, and discloses a biporous catalyst, its preparation method, and its application in the reaction of waste plastics to produce low-carbon olefins. The biporous catalyst comprises ZSM-11 molecular sieve, SBA-3 all-silica mesoporous molecular sieve, and optional metal oxides. Based on the total weight of the biporous catalyst, the content of ZSM-11 molecular sieve is 54-90% by weight, the content of SBA-3 all-silica mesoporous molecular sieve is 10-40% by weight, and the content of metal oxides is 0-6% by weight. The specific surface area of ​​the biporous catalyst is 420-630 m². 2 The pore volume is 0.3-0.5 mL / g. This dual-pore catalyst, when applied to waste plastics, provides a new pathway for the one-step catalytic conversion and utilization of waste plastics, solving the problem of waste plastic recycling and increasing the production of important chemical raw materials such as low-carbon olefins.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalysts and the field of recycling of polymer materials, in particular, to a double-pore catalyst, a preparation method thereof and application of the double-pore catalyst in a reaction of producing low-carbon olefins from waste plastics. BACKGROUND

[0002] Since the 20th century, plastic products have been widely used in various fields worldwide due to their light weight, high strength, corrosion resistance, good chemical stability, easy processing and aesthetic and practical characteristics. However, plastics are difficult to degrade naturally, and conventional landfill technology, although it has low investment and simple operation, will occupy a large amount of land and cause land pollution. Incineration technology can achieve the requirement of reduction, and recover part of the energy, but this process easily releases a large amount of hydrocarbons, nitrogen compounds, sulfides and toxic substances, which directly threatens the health of humans and the ecological environment. Therefore, the recycling and high-value utilization of waste plastics, as a measure to save energy and protect the environment, have been widely valued by countries around the world. The main methods of recycling and utilizing waste plastics include classification recycling, production of monomer raw materials, production of clean fuel and power generation.

[0003] Large-scale waste plastic recycling and utilization enterprises with standardized operation will gradually further classify the recycled waste plastics, continuously develop and apply new technologies and new products of waste plastics, gradually expand the application field of waste plastics, and improve the added value of regenerated plastic products. In the prior art, the chemical recycling scheme of waste plastics is mainly waste plastic cracking technology. Waste plastic cracking includes three basic methods, namely thermal cracking method (one-stage method), catalytic cracking method (one-stage method) and thermal cracking-catalytic modification method (two-stage method). The earliest developed waste plastic cracking technology is thermal cracking technology. This technology refers to a thermal conversion process in which high-temperature anaerobic chemical decomposition reaction occurs to convert large-molecular-weight organic matter in waste plastic products into small-molecular-weight liquid matter, fuel gas and coke. The reaction temperature of this process is generally controlled at 350-900℃. If a catalyst is added during the thermal cracking process, it is a catalytic thermal cracking technology, which can not only reduce the cracking temperature, but also improve the product performance. The thermal cracking-catalytic modification method is an improvement of the catalytic cracking method, which uses a catalyst to catalytically modify the cracking gas after thermal cracking of waste plastics. This method has higher product quality, flexible operation and low operating cost than the thermal cracking method and the catalytic cracking method, but the process is more complex.

[0004] The pyrolysis technology for treating waste plastics has wide flexibility, good energy recovery, and is one of the waste plastic treatment technologies with wide application prospect. In the prior art, the products produced by the one-step thermal cracking method and the one-step catalytic cracking method are mainly fuel oil, and only a small amount of low-carbon olefins (ethylene, propylene, butene) can be obtained. If a large amount of low-carbon olefins is needed, a two-stage method of thermal cracking-catalytic modification method needs to be used. Therefore, exploring a new chemical recycling process to produce pure and high-quality final products is an important research direction of plastic waste treatment. SUMMARY

[0005] The purpose of the present application is to solve the problem that the content of low-carbon olefins recovered in the current chemical recycling of waste plastics is low, and to provide a dual-pore catalyst, a preparation method thereof, and an application thereof in the reaction of producing low-carbon olefins from waste plastics. The dual-pore catalyst is applied in waste plastics, providing a new way for one-step catalytic conversion of waste plastics, solving the problem of waste plastic recycling, and increasing the production of important chemical raw material low-carbon olefins.

[0006] In order to achieve the above-mentioned purpose, the first aspect of the present application provides a dual-pore catalyst, wherein the dual-pore catalyst comprises ZSM-11 molecular sieve, SBA-3 full-silicon mesoporous molecular sieve and optional metal oxide, and the content of the ZSM-11 molecular sieve is 54-90% by weight, the content of the SBA-3 full-silicon mesoporous molecular sieve is 10-40% by weight, and the content of the metal oxide is 0-6% by weight, based on the total weight of the dual-pore catalyst.

[0007] The specific surface area of the dual-pore catalyst is 420-630 m 2 / g, and the pore volume is 0.3-0.5 mL / g.

[0008] The second aspect of the present application provides a preparation method of the aforementioned dual-pore catalyst, wherein the preparation method comprises:

[0009] (1) mixing and contacting an aqueous solution of ZSM-11 molecular sieve and optional metal oxide precursor to react, and then performing water removal and drying treatment to obtain a microporous molecular sieve dry powder;

[0010] (2) mixing the microporous molecular sieve dry powder and SBA-3 full-silicon mesoporous molecular sieve raw powder and performing ball milling treatment, and then performing calcination treatment to obtain the dual-pore catalyst.

[0011] The third aspect of the present application provides an application of the aforementioned dual-pore catalyst in the reaction of directly catalytically cracking waste plastics to produce low-carbon olefins.

[0012] Compared with the prior art, the technical scheme of the present application has the following advantages:

[0013] (1) The double-hole catalyst provided by the application has stable structure, good high-temperature resistance, and can ensure no change in use under long-term high-temperature conditions in the catalytic cracking reaction of waste plastics.

[0014] (2) The double-hole catalyst provided by the application comprises zeolite molecular sieves with certain surface acidity, mesoporous materials with large pore diameters, and metal oxides for adjusting surface acidity and electronic distribution, the chemical structure of the catalyst is beneficial to the cracking of waste plastic macromolecules and the generation of target products, and the pore structure of the catalyst is beneficial to the diffusion of raw material and product molecules in the reaction process.

[0015] (3) The double-hole catalyst provided by the application can convert waste plastics into low-carbon olefins in one step when used in the reaction of directly catalytically cracking waste plastics to produce low-carbon olefins, and is a new method for chemical recycling of waste plastics. The method not only solves the problem of recycling waste plastics, but also increases the production of important chemical raw material low-carbon olefins, and has good economic benefits.

[0016] (4) The double-hole catalyst provided by the application has mild process conditions, is easy to operate, and has low requirements for the reaction device when used in the reaction of directly catalytically cracking waste plastics to produce low-carbon olefins.

[0017] Other features and advantages of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the specification, and are used together with the following specific embodiments to explain the application, but do not constitute a limitation on the application. In the drawings:

[0019] Figure 1 is the small-angle X-ray diffraction (XRD) spectrum of the double-hole catalyst A prepared in Example 1 of the application;

[0020] Figure 2 is the wide-angle X-ray diffraction (XRD) spectrum of the double-hole catalyst A prepared in Example 1 of the application;

[0021] Figure 3 is the pore size distribution graph of the double-hole catalyst A prepared in Example 1 of the application. DETAILED DESCRIPTION

[0022] The endpoints of the ranges and any values disclosed in this document are not limited to the precise values stated. The ranges and values should be interpreted as being approximate. For numeric values, the endpoints of each range, the endpoints of each range and individual point values, and individual point values can be combined with each other to form one or more new numeric ranges, which should be considered as specifically disclosed herein.

[0023] As described above, the first aspect of the present application provides a dual-pore catalyst, wherein the dual-pore catalyst comprises ZSM-11 molecular sieve, SBA-3 full-silica mesoporous molecular sieve and optional metal oxide, and the content of the ZSM-11 molecular sieve is 54-90 wt%, the content of the SBA-3 full-silica mesoporous molecular sieve is 10-40 wt%, and the content of the metal oxide is 0-6 wt% based on the total weight of the dual-pore catalyst;

[0024] The specific surface area of the dual-pore catalyst is 420-630 m 2 / g, and the pore volume is 0.3-0.5 mL / g.

[0025] The inventors of the present application found that there is no process for directly catalytic cracking of waste plastics to produce low-carbon olefins (including ethylene, propylene and butene) in the prior art, and the purpose of the present application is to solve this problem. According to the understanding of the physical and chemical properties of heterogeneous catalysts by the inventors, the catalyst for directly preparing low-carbon olefins by catalytic cracking of waste plastics should have certain acidity and good hydrothermal stability. Based on the above requirements, Pentasil type zeolite molecular sieve with stable framework structure and certain acidity is very suitable as the main component of the waste plastic cracking catalyst. As Pentasil type zeolite molecular sieve, ZSM-11 molecular sieve and ZSM-5 molecular sieve have similar chemical composition, and both have elliptical ten-membered ring cross-pore structure. However, compared with ZSM-5 molecular sieve, the pore structure of ZSM-11 molecular sieve is more regular, and the framework symmetry is better, which is more suitable for high-temperature reaction. However, similar to ZSM-5 molecular sieve, the pore size of ZSM-11 zeolite molecular sieve is small (the pore size is between 0.50-0.55 nm), and the pore volume is also small (between 0.1-0.3 cm 3 / g), and the waste plastics are high molecular products with large molecular weight and long molecular chain. During the cracking reaction of waste plastic products, the diffusion of large-sized reactant molecules and product molecules in the narrow pore is difficult, which not only affects the contact of reactants with active centers, but also easily leads to the occurrence of deep dehydrogenation and other side reactions, thereby causing the performance of the catalyst to decrease. Compared with zeolite molecular sieve, the pore size of SBA-3 full-silica mesoporous molecular sieve material is large (greater than 2.0 nm), and the pore volume is large (which can reach 0.9 cm 3 / g, which is very suitable for catalytic reactions involving macromolecules. However, the SBA-3 full-silicon mesoporous molecular sieve material is a full-silicon material, and the surface acidity is extremely weak, which is not suitable for catalyzing waste plastic cracking reactions alone as a catalyst. The inventors of the present application found, during the development and research of waste plastic cracking catalysts, that if the structural advantages of full-silicon mesoporous inorganic materials and the surface acid sites of zeolite molecular sieves are comprehensively utilized, a certain amount of SBA-3 full-silicon mesoporous molecular sieves and ZSM-11 zeolite molecular sieves are mixed, which can effectively improve the specific surface area and pore volume of the catalyst and significantly improve the internal diffusion performance in the reaction.

[0026] In addition, the use of metal oxides to appropriately adjust the surface acidity and electron distribution of the cracking catalyst can effectively promote the progress of the cracking reaction and the generation of target products. The dual-pore catalyst containing ZSM-11 zeolite molecular sieves, SBA-3 full-silicon mesoporous molecular sieves, and metal oxides, when applied to the catalytic conversion reaction of waste plastics as a cracking catalyst, can not only effectively improve the activity of the cracking catalyst, but also increase the selectivity of low-carbon olefins.

[0027] According to the present application, preferably, the content of the ZSM-11 molecular sieves is 60-84% by weight, the content of the SBA-3 full-silicon mesoporous molecular sieves is 15-35% by weight, and the content of the metal oxides is 1-5% by weight, based on the total weight of the dual-pore catalyst; more preferably, the content of the ZSM-11 molecular sieves is 66-78% by weight, the content of the SBA-3 full-silicon mesoporous molecular sieves is 20-30% by weight, and the content of the metal oxides is 2-4% by weight, based on the total weight of the dual-pore catalyst. In the present application, the use of the aforementioned specific content of each component can make the prepared dual-pore catalyst have better catalytic activity and higher selectivity of low-carbon olefins when used in the reaction of directly catalytically cracking waste plastics to prepare low-carbon olefins.

[0028] According to the present application, preferably, the specific surface area of the dual-pore catalyst is 500-590 m 2 / g, and the pore volume is 0.34-0.46 mL / g; more preferably, the specific surface area of the dual-pore catalyst is 535-570 m 2 / g, and the pore volume is 0.38-0.43 mL / g. In the present application, the use of the aforementioned dual-pore catalyst with specific parameters can make the dual-pore catalyst have better catalytic activity and higher selectivity of low-carbon olefins when used in the reaction of directly catalytically cracking waste plastics to prepare low-carbon olefins.

[0029] According to the present application, the pore size of the dual-pore catalyst is bimodal distribution, the micropore size is 0.4-0.6 nm, and the mesopore size is 2-4 nm.

[0030] According to the present application, the SiO2 / Al2O3 molar ratio of the ZSM-11 molecular sieve is 30-300. In the present application, the ZSM-11 molecular sieve can be obtained by commercial purchase. Specifically, the ZSM-11 molecular sieve can be: ZSM-11 molecular sieve with a SiO2 / Al2O3 molar ratio of 35 purchased from Nanjing Jicang Nanometer Technology Co., Ltd.; ZSM-11 molecular sieve with a SiO2 / Al2O3 molar ratio of 90 purchased from Zhuoran Environmental Protection Technology (Dalian) Co., Ltd.; ZSM-11 molecular sieve with model numbers JL-A03 (SiO2 / Al2O3 molar ratio of 50), JL-A04 (SiO2 / Al2O3 molar ratio of 80) and JL-A05 (SiO2 / Al2O3 molar ratio of 280) purchased from Zibo Julong Chemical Technology Co., Ltd.

[0031] According to the present application, the metal oxide is an alkaline earth metal oxide and / or a transition metal oxide; preferably, the metal oxide is selected from one or more of magnesium oxide, calcium oxide, strontium oxide, barium oxide and zinc oxide. In the present application, the specific metal oxide selected from the present application can improve the surface acidity and surface electron distribution of the cracking catalyst, so that the catalyst surface properties are more suitable for the performance of waste plastic cracking reaction.

[0032] According to the present application, the preparation method of the SBA-3 all-silicon mesoporous molecular sieve crude powder comprises: mixing and contacting a template agent, a silicon source, an inorganic acid, a metal salt and water to obtain a mixture, and subjecting the mixture to crystallization, filtration, washing and drying treatment to obtain the SBA-3 all-silicon mesoporous molecular sieve crude powder.

[0033] According to the present application, the template agent is a cationic surfactant, preferably one or more of dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide and octadecyltrimethylammonium bromide.

[0034] According to the present application, the silicon source is an organic silicon source and / or an inorganic silicon source, preferably tetraethyl orthosilicate and / or water glass.

[0035] According to the present application, the inorganic acid is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, acetic acid and citric acid, preferably phosphoric acid and / or acetic acid.

[0036] According to the present application, the metal salt is selected from one or more of chlorides, bromides, nitrates and sulfates of alkali metals, preferably one or more of sodium nitrate, sodium chloride, sodium bromide, sodium sulfate, potassium nitrate, potassium chloride, potassium bromide and potassium sulfate.

[0037] According to the present application, the molar ratio of the silicon source, the template agent, the inorganic acid, the metal salt and the water is 1: (0.05-2.0): (0.5-10): (0.2-5.0): (20-400); preferably 1: (0.1-1.2): (1-6): (0.5-2.0): (50-200).

[0038] According to the present application, the mixing and contacting condition includes: temperature of 15-50℃, preferably 20-40℃; time of 20-120min, preferably 30-60min. In order to facilitate the uniform mixing of the substances, according to a preferred embodiment of the present application, the hydrolysis process is carried out under stirring condition.

[0039] According to the present application, the crystallization condition includes: temperature of 15-50℃, time of 3-120h; preferably, the crystallization condition includes: temperature of 20-40℃, time of 8-50h.

[0040] According to the present application, the filtration method is not particularly limited, and can be a filtration method known in the art, including gravity filtration, pressure filtration, vacuum filtration or centrifugal filtration. Preferably, the filtration process specifically includes: using a suction filter bottle, vacuumizing the bottom side of the funnel or using a centrifugal filter to filter.

[0041] According to the present application, the washing condition is not particularly limited, for example, the washing process can include: after filtration, washing the solid product with distilled water repeatedly (the number of washing times can be 2-10), and then performing suction filtration.

[0042] According to the present application, the drying process can be carried out in a drying oven, and the drying condition can include: temperature of 60-150℃, time of 2-30h; preferably, the drying condition includes: temperature of 70-110℃, time of 6-20h.

[0043] The second aspect of the present application provides a preparation method of the aforementioned dual-pore catalyst, wherein the preparation method includes:

[0044] (1) mixing and contacting the ZSM-11 molecular sieve and the optional metal oxide precursor aqueous solution to react; then performing water removal and drying treatment to obtain a microporous molecular sieve dry powder;

[0045] (2) mixing the microporous molecular sieve dry powder and the SBA-3 all-silicon mesoporous molecular sieve raw powder and performing ball milling treatment, and then performing calcination treatment to obtain the dual-pore catalyst.

[0046] According to the present application, in step (1), the aqueous solution of metal oxide precursor comprises a metal salt and water; the metal salt is an aqueous soluble salt of alkaline earth metal and / or transition metal, preferably nitrate of one or more of magnesium, calcium, strontium, barium and zinc.

[0047] According to the present application, in step (1), the aqueous solution of metal oxide precursor has a mass concentration of 0.2-3.0%, preferably 0.4-1.5%.

[0048] According to the present application, in step (1), the weight ratio of ZSM-11 molecular sieve to the aqueous solution of metal oxide precursor is 1:(3-30), preferably 1:(8-20).

[0049] According to the present application, in step (1), the contacting reaction is carried out under the following conditions: temperature of 10-100℃, preferably 30-80℃; time of 0.5-50h, preferably 2-20h. Preferably, in order to achieve better mixing effect, the ZSM-11 molecular sieve and the aqueous solution of metal oxide precursor can be rapidly stirred or the mixing efficiency can be improved by means of ultrasonic during the mixing process.

[0050] According to the present application, in step (1), the method for removing water is not particularly limited and can be any method known in the art, such as evaporation using a rotary evaporator or removal of water by heating and stirring.

[0051] According to the present application, in step (1), the drying is carried out under the following conditions: temperature of 60-150℃, preferably 80-130℃; time of 1-30h, preferably 3-20h.

[0052] According to the present application, in step (2), the weight ratio of the microporous molecular sieve dry powder to the SBA-3 all-silicon mesoporous molecular sieve raw powder is 1:(0.1-1.5), preferably 1:(0.3-0.8).

[0053] According to the present application, in step (2), the ball milling is carried out in a ball mill, wherein the diameter of the milling balls can be 2-3mm; the number of the milling balls can be reasonably selected according to the size of the ball mill jar, and for a ball mill jar with a size of 100-300mL, 2-8 milling balls are usually used; the material of the milling balls is agate or polytetrafluoroethylene, preferably agate. The ball milling is carried out under the following conditions: the rotating speed of the milling balls is 200-600r / min, preferably 300-500r / min; the temperature in the ball mill jar is 30-90℃, preferably 40-80℃; the ball milling time is 5-50h, preferably 8-24h.

[0054] According to the present application, in step (2), the conditions of the calcination include: temperature of 450-650℃, preferably 500-600℃; time of 5-40h, preferably 8-20h.

[0055] The third aspect of the present application provides an application of the aforementioned double-pore catalyst in a reaction of direct catalytic cracking of waste plastics to produce low-carbon olefins.

[0056] According to the present application, the application includes: contacting the waste plastic powder or particles with the double-pore catalyst under certain conditions to carry out a reaction.

[0057] In the present application, the conditions of contacting the waste plastic powder or particles with the double-pore catalyst include: the temperature of the contacting can be 420-580℃, preferably 450-540℃; the pressure of the contacting can be 0.01-1.0 Mpa, preferably 0.05-0.5 Mpa; the time of the contacting can be 0.5-12h, preferably 1-5h; and the weight ratio of the double-pore catalyst to the waste plastic powder or particles can be 1: (0.5-50), preferably 1: (2-30).

[0058] The present application will be described in detail below through examples.

[0059] In the following examples and comparative examples:

[0060] The small-angle XRD test of the sample was performed on a high-power rotating target X-ray diffractometer of D8 ADVANCE type produced by BRUKER AXS Company in Germany, and the scanning range was 0.5-10°.

[0061] The wide-angle XRD test of the sample was performed on an X-ray powder diffractometer of X’Pert MPD type produced by Philips Company in the Netherlands, Cu Kα target, and the scanning range was 2θ=5-90 o .

[0062] The pore structure parameter analysis of the sample was performed on an adsorptometer of ASAP2020-M+C type produced by Micromeritics Company in the United States. The sample was vacuum degassed at 350℃ for 4 hours before determination, the specific surface area of the sample was calculated by BET method, and the pore volume was calculated by BJH model.

[0063] The elemental analysis experiment of the sample was performed on an energy dispersive X-ray fluorescence spectrometer of Eagle Ⅲ produced by EDAX Company in the United States.

[0064] The drying oven was produced by Shanghai Yiheng Scientific Instrument Co., Ltd., and the model was DHG-9030A.

[0065] The muffle furnace was produced by CARBOLITE Company, and the model was CWF1100.

[0066] Other reagents used in the examples and comparative examples were purchased from National Pharmaceutical Group Chemical Reagent Co., Ltd., and the purity of the reagents was analytical pure.

[0067] Example 1

[0068] This example is to illustrate the application of the dual-pore catalyst prepared by the application in the reaction of preparing low-carbon olefins from waste plastics.

[0069] (1) Preparation of SBA-3 all-silicon mesoporous molecular sieve raw powder

[0070] The template agent cetyltrimethylammonium bromide was dissolved in deionized water, and stirred at 25°C until it was completely dissolved into a colorless transparent solution. Sodium bromide was added first and stirred for 10 minutes to dissolve it, then phosphoric acid was added and stirred for 10 minutes, and finally tetraethyl orthosilicate was slowly added to the above solution, and the crystallization was continued at 25°C for 24 hours. The molar ratio of tetraethyl orthosilicate, cetyltrimethylammonium bromide, phosphoric acid, sodium bromide and water was 1:0.6:3:1.0:150. After the crystallization was completed, the white solid was obtained by centrifugal filtration. The white solid was washed with deionized water for 5 times, and the solid product was dried at 90°C for 12 hours to obtain SBA-3 all-silicon mesoporous molecular sieve raw powder A.

[0071] (2) Preparation of dual-pore catalyst

[0072] 9.6g of magnesium nitrate hexahydrate was dissolved in 400g of distilled water to prepare an aqueous solution. 36g of ZSM-11 molecular sieve (SiO2 / Al2O3=80) was added to the above magnesium nitrate aqueous solution, and after stirring at 60°C for 5h, the water was removed using a rotary evaporator, and the solid product was dried at 110°C for 8h to obtain microporous molecular sieve dry powder A.

[0073] The above microporous molecular sieve dry powder A and 22g of SBA-3 all-silicon mesoporous molecular sieve raw powder A were added to a 300mL ball mill tank, 6 marblen balls with a diameter of 2mm were put in, and the ball milling was started. The temperature in the ball mill tank was controlled at 50°C, the rotating speed of the grinding ball was 400r / min, and the ball milling time was 10h. The powder obtained after ball milling was calcined at 550°C for 16h to obtain dual-pore catalyst A.

[0074] Based on the total weight of catalyst A, the content of ZSM-11 molecular sieve was 72wt%, the content of SBA-3 all-silicon mesoporous molecular sieve was 25wt%, and the content of magnesium oxide was 3wt%.

[0075] The specific surface area of catalyst A was 548m 2 / g, and the pore volume was 0.40cm 3 / g.

[0076] Figure 1is the small angle XRD pattern of catalyst A, Figure 1 The pattern shows that the sample has diffraction peaks at 6 o Three clear diffraction peaks appeared in the small angle, which proved that the mesoporous material in the catalyst had a typical two-dimensional hexagonal mesoporous structure. This indicates that the SBA-3 full-silicon mesoporous molecular sieve still has a relatively regular mesoporous channel structure after being prepared into a catalyst, and the catalyst preparation process does not destroy the basic structure of the mesoporous molecular sieve.

[0077] Figure 2 is the wide angle XRD pattern of catalyst A, Figure 2 The pattern shows that the wide angle x-ray diffraction angle of the sample is mainly: 2θ = 7.9°, 8.8°, 23.1°, 24.0° and 45.2°. The above diffraction signals are consistent with the diffraction pattern of ZSM-11 molecular sieve, indicating that the ZSM-11 molecular sieve crystal phase does not change obviously during the preparation of the catalyst, and still maintains a good skeleton structure. In addition, there is no diffraction signal corresponding to the metal oxide in the wide angle XRD pattern, indicating that the metal oxide component is in a uniform dispersed state on the catalyst, and the particle size is less than 2nm.

[0078] Figure 3 is the pore size distribution of catalyst A, Figure 3 The pattern shows that the sample has a clear double-pore structure, and the double-pore pore sizes are 0.54nm and 2.5nm respectively. Among them, the pore with a pore size of 0.54nm is provided by the ZSM-11 molecular sieve, and the pore with a pore size of 2.5nm is provided by the SBA-3 full-silicon mesoporous molecular sieve.

[0079] (3) Performance evaluation of waste plastic direct conversion to low-carbon olefin reaction

[0080] The performance evaluation of the waste plastic catalytic cracking reaction of the catalyst was carried out on a fixed bed reaction device. The catalyst loading was 10.0g, the waste polyethylene plastic particle loading was 50.0g, the reaction temperature was 520℃, the reaction pressure was 0.1MPa, the reaction time was 1 hour, after the product was cooled and gas-liquid separated, the gas composition was analyzed by Agilent 6890 gas chromatograph equipped with Al2O3-S capillary chromatographic column and hydrogen flame detector (FID), and the quantitative analysis was carried out by using correction factor; the liquid composition was analyzed by Agilent 7890A gas chromatograph equipped with PONA chromatographic column. The reaction results are shown in Table 1.

[0081] Example 2

[0082] This embodiment is to illustrate the application of the dual-pore catalyst prepared by the application in the reaction of waste plastic to low-carbon olefin.

[0083] (1) Preparation of SBA-3 full-silicon mesoporous molecular sieve

[0084] The template agent dodecyl trimethyl ammonium bromide was dissolved in deionized water, and stirred at 20°C until it was completely dissolved into a colorless transparent solution. Sodium nitrate was added first, and stirred for 20 minutes until it was dissolved. Acetic acid was added, and stirred for 10 minutes. Finally, tetraethyl orthosilicate was slowly added into the above solution, and continued to be stirred at 20°C for 50 hours. The molar ratio of tetraethyl orthosilicate, dodecyl trimethyl ammonium bromide, acetic acid, sodium nitrate and water was 1:1.2:6:2.0:200. After the crystallization was completed, the white solid was obtained by centrifugal filtration. The white solid was washed with deionized water for 8 times, and the solid product was dried at 110°C for 6 hours to obtain SBA-3 full-silicon mesoporous molecular sieve raw powder B.

[0085] (2) Preparation of the dual-pore catalyst

[0086] 2.1g of strontium nitrate was dissolved in 500g of distilled water to prepare an aqueous solution. 39g of ZSM-11 molecular sieve (SiO2 / Al2O3=90) was added into the above aqueous solution of strontium nitrate, and stirred at 80°C for 2 hours. Then, water was removed by using a rotary evaporator, and the solid product was dried at 130°C for 3 hours to obtain microporous molecular sieve dry powder B.

[0087] The above microporous molecular sieve dry powder B and 16g of SBA-3 full-silicon mesoporous molecular sieve raw powder B were added into a 300mL ball mill tank, 8 marblen balls with a diameter of 2mm were put into the tank, and the ball milling was started. The temperature in the ball mill tank was controlled at 80°C, the rotating speed of the milling balls was 500r / min, and the ball milling time was 8 hours. The powder obtained after the ball milling was calcined at 600°C for 8 hours to obtain the dual-pore catalyst B.

[0088] The content of ZSM-11 molecular sieve was 78wt% based on the total weight of the catalyst B, the content of SBA-3 full-silicon mesoporous molecular sieve was 20wt%, and the content of strontium oxide was 2wt%.

[0089] The specific surface area of the catalyst B was 535m 2 / g, the pore volume was 0.38cm 3 / g, and the dual-pore pore size was 0.53nm and 2.8nm, respectively.

[0090] The reaction performance of the catalyst B was tested according to the method for evaluating the reaction performance of the direct conversion of waste plastics to low-carbon olefins in Example 1, and the evaluation results are shown in Table 1.

[0091] Example 3

[0092] This example is to illustrate the dual-pore catalyst prepared by the present application and its application in the reaction of waste plastics to low-carbon olefins.

[0093] (1) Preparation of SBA-3 full-silicon mesoporous molecular sieve

[0094] The template agent octadecyl trimethyl ammonium bromide was dissolved in deionized water, and stirred at 40℃ until it was completely dissolved into a colorless transparent solution. Potassium chloride was added first, and stirred for 10 minutes until it was dissolved. Then phosphoric acid was added, and stirred for 10 minutes. Finally, water glass was slowly added into the above solution, and continued to be stirred at 40℃ for 8 hours of crystallization. The molar ratio of water glass, octadecyl trimethyl ammonium bromide, phosphoric acid, potassium chloride and water was 1:0.1:1:0.5:50. After the crystallization was completed, the white solid was obtained by centrifugal filtration. The white solid was washed with deionized water for 3 times, and the solid product was dried at 70℃ for 20 hours to obtain SBA-3 full-silicon mesoporous molecular sieve raw powder C.

[0095] (2) Preparation of the dual-pore catalyst

[0096] 5.8g of calcium nitrate was dissolved in 300g of distilled water to prepare an aqueous solution. 33g of ZSM-11 molecular sieve (SiO2 / Al2O3=50) was added into the above aqueous solution of calcium nitrate, and stirred at 30℃ for 20 hours. Then water was removed by using a rotary evaporator, and the solid product was dried at 80℃ for 20 hours to obtain microporous molecular sieve dry powder C.

[0097] The above microporous molecular sieve dry powder C and 28g of SBA-3 full-silicon mesoporous molecular sieve raw powder C were added into a 300mL ball mill tank, 4 maroon grinding balls with a diameter of 2mm were put into the tank, and the ball milling was started. The temperature in the ball mill tank was controlled at 40℃, the rotating speed of the grinding balls was 300r / min, and the ball milling time was 24 hours. The powder obtained after the ball milling was calcined at 500℃ for 20 hours to obtain the dual-pore catalyst C.

[0098] The content of ZSM-11 molecular sieve was 66wt% based on the total weight of catalyst C, the content of SBA-3 full-silicon mesoporous molecular sieve was 30wt%, and the content of calcium oxide was 4wt%.

[0099] The specific surface area of catalyst C was 570m 2 / g, the pore volume was 0.43cm 3 / g, and the dual-pore pore size was 0.54nm and 2.4nm, respectively.

[0100] The reaction performance of catalyst C was tested according to the method for evaluating the reaction performance of the direct conversion of waste plastics to low-carbon olefins in step (3) of Example 1, and the evaluation results are shown in Table 1.

[0101] Example 4

[0102] This example is to illustrate the dual-pore catalyst prepared by the present application and its application in the reaction of waste plastics to low-carbon olefins.

[0103] SBA-3 full-silicon mesoporous molecular sieve raw powder A was prepared according to the same method as that in step (1) of Example 1.

[0104] (2) Preparation of the dual-pore catalyst

[0105] A solution was prepared by dissolving 1.8 g of zinc nitrate hexahydrate in 400 g of distilled water. 42 g of ZSM-11 molecular sieve (SiO2 / Al2O3=90) was added to the above solution of zinc nitrate, and after stirring at 60 °C for 5 h, water was removed using a rotary evaporator, and the solid product was dried at 110 °C for 8 h to obtain a microporous molecular sieve dry powder D.

[0106] The above microporous molecular sieve dry powder D and 12 g of SBA-3 all-silica mesoporous molecular sieve raw powder A were added to a 300 mL ball mill tank, 6 marblen balls with a diameter of 2 mm were put in, and ball milling was started. The temperature in the ball mill tank was controlled at 50 °C, the rotation speed of the milling balls was 400 r / min, and the ball milling time was 10 h. The powder obtained after ball milling was calcined at 550 °C for 16 h to obtain a dual-pore catalyst D.

[0107] The content of the ZSM-11 molecular sieve was 84 wt%, the content of the SBA-3 all-silica mesoporous molecular sieve was 15 wt%, and the content of zinc oxide was 1 wt% based on the total weight of the catalyst D.

[0108] The specific surface area of the catalyst D was 500 m 2 / g, the pore volume was 0.34 cm 3 / g, and the dual-pore pore sizes were 0.53 nm and 2.5 nm, respectively.

[0109] The reaction performance of the catalyst D was tested according to the same method of direct conversion of waste plastics to light olefins in step (3) of Example 1, and the evaluation results are shown in Table 1.

[0110] Example 5

[0111] This example is to illustrate the dual-pore catalyst prepared by the application and its application in the reaction of waste plastics to light olefins.

[0112] The SBA-3 all-silica mesoporous molecular sieve raw powder B was prepared according to the same method as in step (1) of Example 2.

[0113] (2) Preparation of the dual-pore catalyst

[0114] A solution was prepared by dissolving 4.3 g of barium nitrate in 300 g of distilled water. 30 g of ZSM-11 molecular sieve (SiO2 / Al2O3=35) was added to the above solution of barium nitrate, and after stirring at 80 °C for 2 h, water was removed using a rotary evaporator, and the solid product was dried at 130 °C for 3 h to obtain a microporous molecular sieve dry powder E.

[0115] The microporous molecular sieve dry powder E and 27 g of SBA-3 all-silica mesoporous molecular sieve raw powder B were added into a 300 mL ball mill jar, 8 maroon balls with a diameter of 2 mm were put into the jar, and the ball milling was started. The temperature in the ball mill jar was controlled at 80 ℃, the rotating speed of the balls was 500 r / min, and the ball milling time was 8 h. The powder obtained after the ball milling was calcined at 600 ℃ for 8 h to obtain the dual-pore catalyst E.

[0116] The content of the ZSM-11 molecular sieve was 60% by weight, the content of the SBA-3 all-silica mesoporous molecular sieve was 35% by weight, and the content of the barium oxide was 5% by weight, based on the total weight of the catalyst E.

[0117] The specific surface area of the catalyst E was 590 m 2 / g, the pore volume was 0.46 cm 3 / g, and the dual-pore pore sizes were 0.55 nm and 2.8 nm, respectively.

[0118] The reaction performance of the catalyst E was tested according to the same method for evaluating the reaction performance of the waste plastic direct conversion to low-carbon olefins in step (3) in Example 1, and the evaluation results are shown in Table 1.

[0119] Example 6

[0120] This example is to illustrate the dual-pore catalyst prepared by the application and the application of the dual-pore catalyst in the reaction of waste plastic to low-carbon olefins.

[0121] The SBA-3 all-silica mesoporous molecular sieve raw powder A was prepared according to the same method as in step (1) in Example 1.

[0122] (2) Preparation of the dual-pore catalyst

[0123] 45 g of ZSM-11 molecular sieve (SiO2 / Al2O3=280) and 8 g of SBA-3 all-silica mesoporous molecular sieve raw powder A were added into a 300 mL ball mill jar, 6 maroon balls with a diameter of 2 mm were put into the jar, and the ball milling was started. The temperature in the ball mill jar was controlled at 50 ℃, the rotating speed of the balls was 400 r / min, and the ball milling time was 10 h. The powder obtained after the ball milling was calcined at 550 ℃ for 16 h to obtain the dual-pore catalyst F.

[0124] The content of the ZSM-11 molecular sieve was 90% by weight, and the content of the SBA-3 all-silica mesoporous molecular sieve was 10% by weight, based on the total weight of the catalyst F.

[0125] The specific surface area of the catalyst F was 420 m 2 / g, the pore volume was 0.30 cm 3 / g, and the dual-pore pore sizes were 0.54 nm and 2.5 nm, respectively.

[0126] The reaction performance of catalyst F was tested according to the same reaction performance evaluation method of direct conversion of waste plastics to light olefins in step (3) in Example 1, and the evaluation results are listed in Table 1.

[0127] Example 7

[0128] This example is to illustrate the preparation of the dual-pore catalyst and its application in the reaction of waste plastics to light olefins.

[0129] SBA-3 full-silica mesoporous molecular sieve raw powder B was prepared according to the same method as step (1) in Example 2.

[0130] (2) Preparation of dual-pore catalyst

[0131] 19.2 g of magnesium nitrate hexahydrate was dissolved in 600 g of distilled water to prepare an aqueous solution. 27 g of ZSM-11 molecular sieve (SiO2 / Al2O3=35) was added to the above magnesium nitrate aqueous solution, and after stirring at 80°C for 2 h, water was removed using a rotary evaporator, and the solid product was dried at 130°C for 3 h to obtain microporous molecular sieve dry powder G.

[0132] The above microporous molecular sieve dry powder G and 30 g of SBA-3 full-silica mesoporous molecular sieve raw powder B were added to a 300 mL ball mill tank, 8 maroon grinding balls with a diameter of 2 mm were put in, and the ball milling was started. The temperature in the ball mill tank was controlled at 80°C, the rotation speed of the grinding balls was 500 r / min, and the ball milling time was 8 h. The powder obtained after ball milling was calcined at 600°C for 8 h to obtain dual-pore catalyst G.

[0133] Based on the total weight of catalyst G, the content of ZSM-11 molecular sieve was 54% by weight, the content of SBA-3 full-silica mesoporous molecular sieve was 40% by weight, and the content of magnesium oxide was 6% by weight.

[0134] The specific surface area of catalyst G was 630 m 2 / g, the pore volume was 0.50 cm 3 / g, and the dual-pore pore size was 0.55 nm and 2.8 nm, respectively.

[0135] The reaction performance of catalyst G was tested according to the same reaction performance evaluation method of direct conversion of waste plastics to light olefins in step (3) in Example 1, and the evaluation results are listed in Table 1.

[0136] Comparative Example 1

[0137] SBA-3 full-silica mesoporous molecular sieve raw powder A was prepared according to the same method as step (1) in Example 1.

[0138] (2) Preparation of dual-pore catalyst

[0139] A solution of 10.2 g of barium nitrate was prepared by dissolving it in 200 g of distilled water. 15 g of ZSM-11 molecular sieve (SiO2 / Al2O3=80) was added to the above solution of barium nitrate, and after stirring at 60°C for 5 h, water was removed using a rotary evaporator, and the solid product was dried at 110°C for 8 h to obtain a microporous molecular sieve dry powder D1.

[0140] The microporous molecular sieve dry powder D1 and 46 g of SBA-3 all-silica mesoporous molecular sieve raw powder A were added to a 300 mL ball mill jar, 6 maroon balls with a diameter of 2 mm were put in, and ball milling was started. The temperature in the ball mill jar was controlled at 50°C, the rotation speed of the grinding balls was 400 r / min, and the ball milling time was 10 h. The powder obtained after ball milling was calcined at 550°C for 16 h to obtain a dual-pore catalyst D1.

[0141] The content of ZSM-11 molecular sieve was 30 wt%, the content of SBA-3 all-silica mesoporous molecular sieve was 58 wt%, and the content of barium oxide was 12 wt% based on the total weight of catalyst D1.

[0142] The specific surface area of catalyst D1 was 800 m 2 / g, the pore volume was 0.60 cm 3 / g, and the dual-pore pore sizes were 0.54 nm and 2.5 nm, respectively.

[0143] The reaction performance of catalyst D1 was tested according to the same method of direct conversion of waste plastics to light olefins in step (3) of Example 1, and the evaluation results are shown in Table 1.

[0144] Comparative Example 2

[0145] SBA-3 all-silica mesoporous molecular sieve raw powder B was prepared according to the same method as in step (1) of Example 2.

[0146] (2) Preparation of a dual-pore catalyst

[0147] 47.5 g of ZSM-11 molecular sieve (SiO2 / Al2O3=35) and 4 g of SBA-3 all-silica mesoporous molecular sieve raw powder B were added to a 300 mL ball mill jar, 8 maroon balls with a diameter of 2 mm were put in, and ball milling was started. The temperature in the ball mill jar was controlled at 80°C, the rotation speed of the grinding balls was 500 r / min, and the ball milling time was 8 h. The powder obtained after ball milling was calcined at 600°C for 8 h to obtain a dual-pore catalyst D2.

[0148] The content of ZSM-11 molecular sieve was 95 wt%, and the content of SBA-3 all-silica mesoporous molecular sieve was 5 wt% based on the total weight of catalyst D2.

[0149] The specific surface area of catalyst D2 was 380 m 2 / g, pore volume is 0.27 cm 3 / g, the double pore diameters are 0.55 nm and 2.8 nm, respectively.

[0150] The reaction performance of catalyst D2 was tested according to the same reaction performance evaluation method of direct conversion of waste plastics to light olefins in step (3) in Example 1, and the evaluation results are listed in Table 1.

[0151] Comparative Example 3

[0152] SBA-3 full-silica mesoporous molecular sieve A was prepared according to the same method in step (1) in Example 1, and SBA-3 full-silica mesoporous molecular sieve A was calcined at 550 ℃ for 16 h to obtain SBA-3 full-silica mesoporous molecular sieve A.

[0153] The specific surface area of SBA-3 full-silica mesoporous molecular sieve A is 1217 m 2 / g, pore volume is 0.92 cm 3 / g, pore diameter is 2.5 nm.

[0154] Step (2) in Example 1 was cancelled.

[0155] The reaction performance of SBA-3 full-silica mesoporous molecular sieve A was tested according to the same reaction performance evaluation method of direct conversion of waste plastics to light olefins in step (3) in Example 1, and the evaluation results are listed in Table 1.

[0156] Comparative Example 4

[0157] The catalyst was prepared according to the same method in Example 1, except that:

[0158] Step (1) in Example 1 was cancelled.

[0159] Catalyst D3 was prepared according to the following steps: 9.6 g of magnesium nitrate hexahydrate was dissolved in 400 g of distilled water to prepare an aqueous solution. 36 g of ZSM-11 molecular sieve (SiO2 / Al2O3=80) was added to the above magnesium nitrate aqueous solution, and after stirring at 60 ℃ for 5 h, water was removed using a rotary evaporator, and the solid product was dried at 110 ℃ for 8 h and calcined at 550 ℃ for 16 h to obtain catalyst D3.

[0160] The reaction performance of catalyst D3 was tested according to the same reaction performance evaluation method of direct conversion of waste plastics to light olefins in step (3) in Example 1, and the evaluation results are listed in Table 1.

[0161] Comparative Example 5

[0162] The catalyst was prepared according to the same method in Example 1, except that:

[0163] Step (1) and step (2) in Example 1 were cancelled.

[0164] The reaction performance of ZSM-11 molecular sieve (SiO2 / Al2O3=80) was tested according to the same method of direct conversion of waste plastics to light olefins reaction performance evaluation method of step (3) in Example 1, and the evaluation results are listed in Table 1.

[0165] Comparative Example 6

[0166] SBA-3 all-silica mesoporous molecular sieve raw powder A was prepared according to the same method of step (1) in Example 1.

[0167] The ball milling process in step (2) in Example 1 was cancelled.

[0168] (2) Preparation of dual-pore catalyst

[0169] 10.2 g of barium nitrate was dissolved in 200 g of distilled water to prepare an aqueous solution. 15 g of ZSM-11 molecular sieve (SiO2 / Al2O3=80) was added to the above barium nitrate aqueous solution, and after stirring at 60°C for 5 h, water was removed using a rotary evaporator, and the solid product was dried at 110°C for 8 h to obtain microporous molecular sieve dry powder D1.

[0170] The above microporous molecular sieve dry powder D1 and 46 g of SBA-3 all-silica mesoporous molecular sieve raw powder A were mixed and calcined at 550°C for 16 h to obtain a dual-pore catalyst D4.

[0171] The reaction performance of catalyst D4 was tested according to the same method of direct conversion of waste plastics to light olefins reaction performance evaluation method of step (3) in Example 1, and the evaluation results are listed in Table 1.

[0172] Comparative Example 7

[0173] The catalyst was prepared according to the same method as Example 1, except that:

[0174] Step (1) in Example 1 was cancelled.

[0175] Catalyst D5 was prepared according to the same method as step (2) in Example 1, and SBA-3 all-silica mesoporous molecular sieve raw powder A was replaced by commercially available silica powder (specific surface area of 274 m 2 / g, pore volume of 0.54 cm 3 / g), and the specific process was as follows:

[0176] A solution was prepared by dissolving 9.6 g of magnesium nitrate hexahydrate in 400 g of distilled water. 36 g of ZSM-11 molecular sieve (SiO2 / Al2O3=80) was added to the above magnesium nitrate solution, and after stirring at 60°C for 5 h, water was removed using a rotary evaporator, and the solid product was dried at 110°C for 8 h to obtain microporous molecular sieve dry powder A.

[0177] The above microporous molecular sieve dry powder A and 12.5 g of commercially available silica powder (specific surface area 274 m 2 / g, pore volume 0.54 cm 3 / g) were added to a 300 mL ball mill tank, 6 maroon balls with a diameter of 2 mm were put in, and ball milling was started. The temperature in the ball mill tank was controlled at 50°C, the rotation speed of the ball mill was 400 r / min, and the ball milling time was 10 h. The powder obtained after ball milling was calcined at 550°C for 16 h to obtain a dual-pore catalyst D5.

[0178] The reaction performance of catalyst D5 was tested according to the same method for evaluating the reaction performance of direct conversion of waste plastics to low-carbon olefins in step (3) in Example 1, and the evaluation results are shown in Table 1.

[0179] Table 1

[0180]

[0181] From the above results, it can be seen that the dual-pore catalyst provided by the present application can catalytically convert waste plastics to low-carbon olefins. The conversion rate of waste plastics is 100%, and the yield of low-carbon olefins is high.

[0182] In Comparative Example 1, the content of SBA-3 all-silicon mesoporous molecular sieve is too high, the content of ZSM-11 molecular sieve is too low, and the content of metal oxide is not within the range defined by the present application. Due to the small number of acid sites on the catalyst and the insufficient activation sites during the reaction, the conversion rate of the raw material is low, and the yield of low-carbon olefins is low.

[0183] In Comparative Example 2, the content of SBA-3 all-silicon mesoporous molecular sieve is too low, and the content of ZSM-11 molecular sieve is too high. Due to the small number of large pore channels in the catalyst, the diffusion of reactant and product molecules is hindered during the reaction, resulting in a low yield of low-carbon olefins.

[0184] In Comparative Example 3, only SBA-3 all-silicon mesoporous molecular sieve is used as a catalyst. Since the surface of the all-silicon mesoporous molecular sieve has very weak acidity, it is not conducive to the cracking reaction of waste plastic polymers, resulting in a low conversion rate and a low yield of low-carbon olefins.

[0185] In the comparative example 4, the catalyst only contains ZSM-11 molecular sieve and metal oxide, and no SBA-3 full-silicon mesoporous molecular sieve is added. Due to the fact that the catalyst contains almost no mesoporous channels, the diffusion of reactant and product molecules is seriously hindered during the reaction, which results in a low yield of light olefins.

[0186] In the comparative example 5, the catalyst only contains ZSM-11 molecular sieve, and no SBA-3 full-silicon mesoporous molecular sieve and metal oxide are added. Due to the fact that the catalyst contains almost no mesoporous channels, the diffusion of reactant and product molecules is seriously hindered during the reaction, which results in a low yield of light olefins.

[0187] In the comparative example 6, the ball milling process is cancelled, and the ZSM-11 molecular sieve and the SBA-3 full-silicon mesoporous molecular sieve are mixed directly. Due to the fact that the ZSM-11 molecular sieve with acid sites and the SBA-3 molecular sieve with mesoporous structure are not mixed uniformly, the yield of light olefins is low.

[0188] In the comparative example 7, the commercially available silica powder is used to replace the SBA-3 full-silicon mesoporous molecular sieve. Due to the fact that the mesoporous channel structure of the commercially available silica is irregular, the yield of light olefins is low.

[0189] The above describes the preferred embodiments of the present application in detail, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the disclosed content of the present application, and all fall within the protection scope of the present application.

Claims

1. The application of a dual-porous catalyst in the direct catalytic cracking of waste plastics to produce low-carbon olefins, the application comprising: Waste plastic powder or granules are reacted with the biporous catalyst, wherein the waste plastic is waste polyethylene plastic. The biporous catalyst comprises ZSM-11 molecular sieve, SBA-3 all-silica mesoporous molecular sieve, and metal oxide, wherein, based on the total weight of the biporous catalyst, the content of ZSM-11 molecular sieve is 54-90% by weight, the content of SBA-3 all-silica mesoporous molecular sieve is 10-40% by weight, and the content of metal oxide is 0-6% by weight. The pore size of the dual-porous catalyst exhibits a bimodal distribution, and the specific surface area of ​​the dual-porous catalyst is 420-630 m². 2 / g, pore volume is 0.3-0.5mL / g, micropore diameter is 0.4-0.6nm, and mesopore diameter is 2-4nm; The method for preparing the aforementioned dual-porous catalyst includes: (1) The ZSM-11 molecular sieve and the aqueous solution of the metal oxide precursor are mixed and reacted; then the mixture is dehydrated and dried to obtain microporous molecular sieve powder. (2) The microporous molecular sieve dry powder and SBA-3 all-silica mesoporous molecular sieve raw powder are mixed and ball-milled, and then calcined to obtain a dual-pore catalyst.

2. The application according to claim 1, wherein, Based on the total weight of the dual-porous catalyst, the content of ZSM-11 molecular sieve is 60-84% by weight, the content of SBA-3 all-silica mesoporous molecular sieve is 15-35% by weight, and the content of metal oxide is 1-5% by weight.

3. The application according to claim 2, wherein, Based on the total weight of the dual-porous catalyst, the content of ZSM-11 molecular sieve is 66-78% by weight, the content of SBA-3 all-silica mesoporous molecular sieve is 20-30% by weight, and the content of metal oxide is 2-4% by weight.

4. The application according to any one of claims 1-3, wherein, The specific surface area of ​​the dual-porous catalyst is 500-590 m². 2 / g, with a pore volume of 0.34-0.46 mL / g.

5. The application according to claim 4, wherein, The specific surface area of ​​the dual-porous catalyst is 535-570 m². 2 / g, with a pore volume of 0.38-0.43 mL / g.

6. The application according to any one of claims 1-3, wherein, The SiO2 / Al2O3 molar ratio of the ZSM-11 molecular sieve is 30-300.

7. The application according to any one of claims 1-3, wherein, The metal oxide is an alkaline earth metal oxide and / or a transition metal oxide.

8. The application according to claim 7, wherein, The metal oxide is selected from one or more of magnesium oxide, calcium oxide, strontium oxide, barium oxide, and zinc oxide.

9. The application according to any one of claims 1-3, wherein, The preparation method of the SBA-3 all-silica mesoporous molecular sieve raw powder includes: mixing and contacting a template agent, a silicon source, an inorganic acid, a metal salt, and water to obtain a mixture, and then crystallizing, filtering, washing, and drying the mixture to obtain the SBA-3 all-silica mesoporous molecular sieve raw powder.

10. The application according to claim 9, wherein, The template agent is a cationic surfactant; And / or, the silicon source is an organosilicon source and / or an inorganic silicon source; And / or, the inorganic acid is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, acetic acid, and citric acid; And / or, the metal salt is selected from one or more of alkali metal chlorides, bromides, nitrates and sulfates; And / or, the molar ratio of the silicon source, template agent, inorganic acid, metal salt and water is 1:(0.05-2.0):(0.5-10):(0.2-5.0):(20-400).

11. The application according to claim 10, wherein, The template agent is one or more of dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, and octadecyltrimethylammonium bromide; And / or, the silicon source is tetraethyl orthosilicate and / or water glass; And / or, the inorganic acid is phosphoric acid and / or acetic acid; And / or, the metal salt is one or more of sodium nitrate, sodium chloride, sodium bromide, sodium sulfate, potassium nitrate, potassium chloride, potassium bromide, and potassium sulfate; And / or, the molar ratio of the silicon source, template agent, inorganic acid, metal salt and water is 1:(0.1-1.2):(1-6):(0.5-2.0):(50-200).

12. The application according to claim 1, wherein, The aqueous solution of the metal oxide precursor comprises a metal salt and water; the metal salt is a water-soluble salt of an alkaline earth metal and / or a transition metal. And / or, the mass concentration of the aqueous solution of the metal oxide precursor is 0.2-3.0%; And / or, the weight ratio of the ZSM-11 molecular sieve to the aqueous solution of the metal oxide precursor is 1:(3-30). And / or, the weight ratio of the microporous molecular sieve dry powder to the SBA-3 all-silica mesoporous molecular sieve raw powder is 1:(0.1-1.5).

13. The application according to claim 12, wherein, The metal salt is one or more nitrates selected from magnesium, calcium, strontium, barium, and zinc; And / or, the weight ratio of the microporous molecular sieve dry powder to the SBA-3 all-silica mesoporous molecular sieve raw powder is 1:(0.3-0.8).

14. The application according to claim 1, wherein, The conditions for the contact reaction include: temperature of 10-100℃ and time of 0.5-50h; And / or, the conditions for ball milling include: a ball rotation speed of 200-600 r / min, a temperature inside the ball mill jar of 30-90℃, and a milling time of 5-50 h; And / or, the calcination conditions include: a temperature of 450-650℃ and a time of 5-40h.

15. The application according to claim 1, wherein, The contact conditions include: a temperature of 420-580℃, a pressure of 0.01-1MPa, and a contact time of 0.5-12h. And / or, the weight ratio of the dual-pore catalyst to waste plastic powder or granules is 1:(0.5-50).

Images