Shaped pyrolysis catalyst, its preparation method and application in low-carbon olefin reaction from waste plastics

Abstract

The present application relates to the field of catalyst and the field of recycling of high polymer materials, and discloses a shaped cracking catalyst, a preparation method thereof and application of the shaped cracking catalyst in a reaction of preparing low-carbon olefins from waste plastics.The shaped cracking catalyst comprises a composite carrier and a bound oxide supported on the composite carrier, the composite carrier comprises modified ZSM-22 molecular sieve and MCM-41 full-silicon mesoporous molecular sieve; and the content of the modified ZSM-22 molecular sieve is 44-60 wt%, the content of the MCM-41 full-silicon mesoporous molecular sieve is 20-50 wt%, and the content of the bound oxide is 6-20 wt% based on the total weight of the shaped cracking catalyst.The shaped cracking catalyst is used in the direct cracking of waste plastics to prepare low-carbon olefins, which is a new one-step catalytic conversion utilization way of waste plastics, solves the problem of recycling of waste plastics, and increases the production of important chemical raw material, i.e.low-carbon olefins.

Description

TECHNICAL FIELD

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

[0002] Plastic products have the characteristics of light weight, high strength, corrosion resistance, good chemical stability, easy processing and aesthetic practicality, and are widely used in various fields worldwide. 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 at the same time, part of the energy can be recovered, but this process can easily release a large amount of hydrocarbons, nitrogen compounds, sulfur compounds and toxic substances, which directly threaten 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 attracted widespread attention. The methods for recycling and utilizing waste plastics mainly include classification recycling, production of monomer raw materials, production of clean fuel and power generation.

[0003] In the prior art, the chemical recycling scheme of waste plastics mainly includes 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 upgrading 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 thermal chemical decomposition reaction occurs under high-temperature anaerobic conditions, and macromolecular mass organic matter in waste plastic products is converted into small-molecular mass liquid matter, fuel gas and coke. The reaction temperature of this process is generally controlled at 350-900℃. If a catalyst is added during thermal cracking, 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 upgrading method, as an improvement of the catalytic cracking method, uses a catalyst to catalytically upgrade 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 cracking technology has wide flexibility in treating waste plastics, good energy recovery, and is one of the waste plastic treatment technologies with wide application prospect. In the prior art, the products produced by one-step thermal cracking method and one-step catalytic cracking method are mainly fuel oil, and only a small amount of low-carbon olefins (ethylene, propylene, butene) can be obtained.

[0005] Therefore, exploring a new chemical recycling process to produce pure and high-quality final products is an important research direction for plastic waste treatment. SUMMARY

[0006] The present application aims at the current situation that the low-carbon olefin content is less in the recycling of waste plastics by chemical recycling, and provides a shaped cracking catalyst, a preparation method thereof and application of the shaped cracking catalyst in the reaction of preparing low-carbon olefin from waste plastics.

[0007] In order to achieve the above-mentioned purpose, the present application provides a shaped cracking catalyst in the first aspect, wherein the shaped cracking catalyst comprises a composite carrier and a bound oxide supported on the composite carrier, the composite carrier comprises modified ZSM-22 molecular sieve and MCM-41 full-silicon mesoporous molecular sieve; and the content of the modified ZSM-22 molecular sieve is 44-60 wt%, the content of the MCM-41 full-silicon mesoporous molecular sieve is 20-50 wt%, and the content of the bound oxide is 6-20 wt% based on the total weight of the shaped cracking catalyst.

[0008] The present application provides a preparation method of the shaped cracking catalyst in the second aspect, wherein the preparation method comprises:

[0009] The modified ZSM-22 molecular sieve, the MCM-41 full-silicon mesoporous molecular sieve, a binder and a extrusion aid are mixed to be extruded, and then dried and calcined to obtain the shaped cracking catalyst.

[0010] The present application provides application of the shaped cracking catalyst in the third aspect, wherein the shaped cracking catalyst is applied in the reaction of preparing low-carbon olefin from waste plastics by direct catalytic cracking.

[0011] Through the above technical solution, the technical solution of the present application has the following advantages:

[0012] (1) The shaped cracking catalyst provided by the present application has raw materials that are easy to obtain, a preparation method that is simple in process and easy to control, and good product repeatability.

[0013] (2) The shaped cracking catalyst provided by the present application comprises zeolite molecular sieve with certain surface acidity and mesoporous material with large pore size, has stable structure, good high-temperature resistance, and is helpful to the diffusion of raw material and product molecules in the cracking reaction process.

[0014] (3) The shaped cracking catalyst provided by the present application can convert waste plastics into low-carbon olefin in one step when used in the reaction of preparing low-carbon olefin from waste plastics by direct catalytic cracking, and is a new method for chemical recycling of waste plastics. The shaped cracking catalyst not only solves the problem of recycling waste plastics, but also increases the production of important chemical raw material low-carbon olefin, and has good economic benefits.

[0015] (4) The molding cracking catalyst provided by the application has mild process conditions, is easy to operate, and has low requirements on the reaction device when used in the reaction of directly catalytically cracking waste plastics to produce low-carbon olefins.

[0016] Other features and advantages of the present application will be described in detail in the following detailed description of the application. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings are included to provide a further understanding of the application, and are incorporated in and constitute a part of this specification, illustrate embodiments of the application, and together with the description serve to explain the principles of the application. In the drawings:

[0018] Figure 1 is a wide-angle X-ray diffraction (XRD) spectrum of modified ZSM-22 molecular sieve A of Example 1;

[0019] Figure 2 is a small-angle X-ray diffraction (XRD) spectrum of MCM-41 full-silica mesoporous molecular sieve A of Example 1. DETAILED DESCRIPTION

[0020] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not critical to the present application. Any numeric range recited is intended to include all derivatives of and combinations with the recited range of endpoints. Numeric ranges include endpoints that are each independently a point or a range.

[0021] As described previously, in the first aspect, the present application provides a molding cracking catalyst, wherein the molding cracking catalyst comprises a composite carrier and a bound oxide supported on the composite carrier, the composite carrier comprises modified ZSM-22 molecular sieve and MCM-41 full-silica mesoporous molecular sieve; and the content of the modified ZSM-22 molecular sieve is 44-60 wt%, the content of the MCM-41 full-silica mesoporous molecular sieve is 20-50 wt%, and the content of the bound oxide is 6-20 wt% based on the total weight of the molding cracking catalyst.

[0022] 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, butene) in the prior art, and one of the purposes of the present application is to solve this problem. According to the understanding of the inventors on the physical and chemical properties of heterogeneous catalysts, the catalyst for directly preparing low-carbon olefins by catalytic cracking of waste plastics should have a certain acidity and good hydrothermal stability. Based on the above requirements, a zeolite molecular sieve with a stable framework structure and a certain acidity is very suitable as the main component of the cracking catalyst. ZSM-22 zeolite molecular sieve has a TON structure topological framework, and the framework structure contains five-membered rings, six-membered rings and ten-membered rings. The one-dimensional channel composed of ten-membered rings is a parallel channel that is not cross-linked, and the pore opening is elliptical. However, because the channel size of the ZSM-22 zeolite molecular sieve is small (0.56-0.58 nm), and the molecular weight of the waste plastic product is large, the molecular chain is also relatively long. During the cracking reaction of the waste plastic product, the large-sized reactant molecules and product molecules are difficult to diffuse in the narrow channel, which not only affects the contact between the reactants and the active centers, but also easily leads to the occurrence of side reactions such as deep dehydrogenation or carbon deposition, thereby causing the performance of the catalyst to decrease. Compared with the ZSM-22 zeolite molecular sieve, the MCM-41 full-silicon mesoporous molecular sieve material has a larger channel size (greater than 2.0 nm) and a large pore volume, and is very suitable for catalytic reactions involving large molecules. However, the surface acidity of the MCM-41 full-silicon mesoporous molecular sieve material is extremely weak, and it is not suitable for being used alone as a catalyst for waste plastic cracking reaction. The inventors of the present application found during the development and research of waste plastic cracking catalysts that if the structural advantages of the full-silicon mesoporous inorganic material and the surface acid centers of the modified ZSM-22 zeolite molecular sieve are comprehensively utilized, a certain amount of MCM-41 full-silicon mesoporous molecular sieve is mixed with the modified ZSM-22 zeolite molecular sieve and is formed into a shape, which is applied to the catalytic conversion reaction of waste plastics as a cracking catalyst, the activity of the cracking catalyst can be effectively improved, and the selectivity of low-carbon olefins can be increased.

[0023] According to the present application, preferably, the content of the modified ZSM-22 zeolite molecular sieve is 47-58 wt%, the content of the MCM-41 full-silicon mesoporous molecular sieve is 24-45 wt%, and the content of the binding oxide is 8-18 wt%, based on the total weight of the shaped cracking catalyst; preferably, the content of the modified ZSM-22 zeolite molecular sieve is 50-55 wt%, the content of the MCM-41 full-silicon mesoporous molecular sieve is 30-40 wt%, and the content of the binding oxide is 10-15 wt%, based on the total weight of the shaped cracking catalyst. In the present application, the use of the specific content of each component described above can make the prepared shaped cracking catalyst have better catalytic activity and higher selectivity of low-carbon olefins when used in the reaction of directly catalytic cracking of waste plastics to prepare low-carbon olefins.

[0024] According to the present application, the adhesive oxide is an oxide obtained after calcination of the adhesive. According to the type of the adhesive, the adhesive oxide can be alumina and / or silica, preferably alumina.

[0025] According to the present application, the specific surface area of the shaped cracking catalyst is 350-700 m 2 / g, and the pore volume is 0.45-0.8 cm 3 / g; preferably, the specific surface area of the shaped cracking catalyst is 384-646 m 2 / g, and the pore volume is 0.52-0.72 cm 3 / g.

[0026] According to the present application, the MCM-41 full-silica mesoporous molecular sieve can be a commercially available MCM-41 full-silica mesoporous molecular sieve product or a self-made MCM-41 full-silica mesoporous molecular sieve, preferably, the specific surface area of the MCM-41 full-silica mesoporous molecular sieve is 900-1300 m 2 / g, the pore volume is 0.8-1.4 cm 3 / g, and the average pore size is 2-4 nm; more preferably, the specific surface area of the MCM-41 full-silica mesoporous molecular sieve is 1000-1200 m 2 / g, the pore volume is 1.0-1.3 cm 3 / g, and the average pore size is 2-3 nm. In the present application, the use of the MCM-41 full-silica mesoporous molecular sieve with the aforementioned specific parameters can make the prepared shaped cracking catalyst have better catalytic activity and higher selectivity when used in the reaction of preparing low-carbon olefins by direct catalytic cracking of waste plastics.

[0027] In the present application, the preparation of the MCM-41 full-silica mesoporous molecular sieve comprises:

[0028] At room temperature, the template agent and the auxiliary template agent are dissolved in deionized water, and the silicon source is added to the above mixture while stirring to obtain a gel mixture; the gel mixture is transferred to a reaction kettle, and crystallization is carried out at 30-120°C for 5-120 hours; after separation and washing, the solid product is dried at 50-90°C under reduced pressure for 2-10 hours, and calcined at 500-600°C for 3-12 hours to obtain the MCM-41 full-silica mesoporous molecular sieve.

[0029] In the above-mentioned method for preparing the MCM-41 full-silica mesoporous molecular sieve, the molar ratio of the silicon source: template agent: auxiliary template agent: water is 1: (0.05-1): (0.05-1): (5-100), preferably 1: (0.1-0.7): (0.1-0.7): (10-50).

[0030] In the above-mentioned method for preparing the MCM-41 full-silica mesoporous molecular sieve, the template agent is a compound with the general formula of [NR1 R 2 R 3 R 4 ] + X － of the formula R 1 R 12 -C 30 R 2 R 3 R 4 R 2 R 3 R 4 R

[0031] In the preparation method of the MCM-41 full-silicon mesoporous molecular sieve, the auxiliary template agent is one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetraisopropylammonium hydroxide, and preferably tetramethylammonium hydroxide.

[0032] In the preparation method of the MCM-41 full-silicon mesoporous molecular sieve, the silicon source can be an organic silicon source or an inorganic silicon source. The organic silicon source can be one or more of organic silicon esters, and preferably one or more of methyl silicate, ethyl silicate, and isopropyl silicate. The inorganic silicon source can be one or more of inorganic silicon-containing compounds, and preferably one or more of water glass, sodium metasilicate, and silica sol.

[0033] In the preparation method of the MCM-41 full-silicon mesoporous molecular sieve, the separation method is not particularly limited and can be a separation method known in the art, including gravity filtration, pressure filtration, vacuum filtration, or centrifugal filtration. Preferably, the separation process specifically includes using a suction filter bottle, vacuumizing the bottom side of the funnel, or using a centrifugal filter to filter.

[0034] In the preparation method of the MCM-41 full-silicon mesoporous molecular sieve, the method for washing the solid product is not particularly limited, for example, the solid product can be washed with deionized water, the volume ratio of the deionized water to the solid product can be 5-20, and the washing times can be 2-8 times.

[0035] According to the present application, the modified ZSM-22 molecular sieve comprises a ZSM-22 zeolite molecular sieve and a modified oxide, and the content of the ZSM-22 zeolite molecular sieve is 93-98% by weight based on the total weight of the modified ZSM-22 molecular sieve, and the content of the modified oxide is 2-7% by weight; preferably, the content of the ZSM-22 zeolite molecular sieve is 94-97.5% by weight based on the total weight of the modified ZSM-22 molecular sieve, and the content of the modified oxide is 2.5-6% by weight; more preferably, the content of the ZSM-22 zeolite molecular sieve is 95-97% by weight based on the total weight of the modified ZSM-22 molecular sieve, and the content of the modified oxide is 3-5% by weight.

[0036] According to the present application, the inventors of the present application use a ZSM-22 zeolite molecular sieve with a SiO2 / Al2O3 molar ratio of 20-100 as the main base component, and introduce an oxide as a modified component, so that the activity of the shaped cracking catalyst and the selectivity of low-carbon olefins can be improved. Preferably, when the SiO2 / Al2O3 molar ratio of the ZSM-22 zeolite molecular sieve is 40-60, the activity of the catalyst and the selectivity of low-carbon olefins can be significantly improved.

[0037] According to the present application, the ZSM-22 zeolite molecular sieve can be obtained by commercial purchase. In the present application, specifically, the ZSM-22 zeolite molecular sieve is more preferably: a ZSM-22 zeolite molecular sieve with a SiO2 / Al2O3 molar ratio of 42 purchased from Tianjin Nanhua Catalyst Co., Ltd.; and a ZSM-22 zeolite molecular sieve with a SiO2 / Al2O3 molar ratio of 60 purchased from Nanjing Jicang Nanometer Technology Co., Ltd.

[0038] According to the present application, the modified oxide is selected from one or more of alkali metal oxides and alkaline earth metal oxides; preferably, the modified oxide is selected from one or more of sodium oxide, potassium oxide, calcium oxide, magnesium oxide, strontium oxide and barium oxide. In the present application, the specific modified oxide selected from the present application has the advantage of being able to effectively improve the surface electron distribution of the ZSM-22 zeolite molecular sieve, and selectively cover part of the excessively strong acid centers, so that the surface properties of the prepared shaped cracking catalyst are more suitable for the performance of waste plastic cracking reactions.

[0039] According to the present application, the preparation method of the modified ZSM-22 molecular sieve comprises:

[0040] The ZSM-22 zeolite molecular sieve is mixed and contacted with an aqueous solution of a modified component; and then subjected to water removal, drying and calcination treatment to obtain a modified ZSM-22 molecular sieve.

[0041] According to the present application, the modified component aqueous solution comprises a metal salt and water; the metal salt is selected from nitrate of one or more of alkali metal and alkaline earth metal, preferably one or more of sodium, potassium, calcium, magnesium, strontium and barium.

[0042] According to the present application, the mass concentration of the modified component aqueous solution is 0.2-10%, preferably 0.6-3%.

[0043] According to the present application, the weight ratio of the ZSM-22 zeolite molecular sieve to the modified component aqueous solution is 1:(3-30), preferably 1:(8-16).

[0044] According to the present application, the conditions of the contact reaction include: temperature is 10-100℃, preferably 30-80℃; time is 0.5-50h, preferably 2-20h. Preferably, in order to achieve better mixing effect, rapid stirring or ultrasonic means can be used to improve the mixing efficiency during the mixing of ZSM-22 zeolite molecular sieve and modified component aqueous solution.

[0045] According to the present application, the water removal method is not particularly limited, which can be a water removal method known in the art, such as using a rotary evaporator to evaporate water, or using a heating stirring method to remove water.

[0046] According to the present application, the drying conditions include: temperature is 60-150℃, preferably 80-130℃; time is 1-30h, preferably 3-20h.

[0047] According to the present application, the calcination conditions include: temperature is 400-700℃, preferably 500-600℃; time is 2-20h, preferably 3-10h.

[0048] In the second aspect, the present application provides a preparation method of a shaped cracking catalyst, which specifically operates as follows: mixing modified ZSM-22 molecular sieve, MCM-41 full-silicon mesoporous molecular sieve, binder and extrusion aid in the presence of an acidic aqueous solution, and then performing extrusion molding, drying and calcination treatment to obtain the shaped cracking catalyst.

[0049] According to the present application, the acidic aqueous solution is selected from one or more of dilute nitric acid, dilute acetic acid, dilute hydrochloric acid, dilute phosphoric acid or dilute sulfuric acid, preferably dilute nitric acid or dilute acetic acid; the concentration of the acidic aqueous solution can be 1-30%, preferably 2-15%.

[0050] According to the present application, the binder is selected from one or more of pseudoboehmite, aluminum hydroxide gel, aluminum sol, gibbsite and bayerite, preferably pseudoboehmite; in the present application, the pseudoboehmite can be obtained by commercial purchase or preparation, and in the present application, specifically, the pseudoboehmite includes one or more of SB type German original imported pseudoboehmite powder (purchased from Beijing Asia Pacific Aohua Chemical Auxiliary Co., Ltd., with a specific surface area of 241 m 2 / g, a pore volume of 0.53 cm 3 / g), P-DF-09-LSi type pseudoboehmite powder (produced by Shandong Aluminum Co., Ltd., with a specific surface area of 286 m 2 / g, a pore volume of 1.08 cm 3 / g), and PB-0101 type macroporous pseudoboehmite powder (produced by Zibo Hengqi Powder New Material Co., Ltd., with a specific surface area of 327 m 2 / g, a pore volume of 1.02 cm 3 / g).

[0051] According to the present application, the extrusion aid is selected from one or more of cellulose, sesbania powder, polyacrylamide, polyvinyl alcohol, glycerol and polyethylene glycol, preferably cellulose or sesbania powder.

[0052] According to the present application, the weight ratio of the modified ZSM-22 molecular sieve, the MCM-41 full-silicon mesoporous molecular sieve, the binder, the extrusion aid and the acidic aqueous solution is 1:(0.2-2.0):(0.1-1.0):(0.05-0.5):(0.3-1.6), preferably 1:(0.4-1.0):(0.2-0.5):(0.1-0.3):(0.7-1.2).

[0053] According to the present application, the calcination conditions include a temperature of 450-650℃, preferably 500-600℃; and a time of 2-30h, preferably 5-16h.

[0054] In a third aspect, the present application provides an application of the shaped cracking catalyst as described above in a reaction of direct catalytic cracking of waste plastics to produce low-carbon olefins.

[0055] According to the present application, the application of the catalyst includes contacting waste plastic powder with the shaped cracking catalyst.

[0056] In the present application, the conditions for contacting the waste plastic powder with the shaped cracking catalyst include: the temperature for contacting can be 420-580℃, preferably 450-540℃; the pressure for contacting can be 0.01-1Mpa, preferably 0.05-0.5Mpa; the time for contacting can be 0.5-12h, preferably 1-5h; and the weight ratio of the shaped cracking catalyst to the waste plastic powder can be 1:(0.5-50), preferably 1:(2-30).

[0057] The present application will be described in detail below through examples.

[0058] In the following examples and comparative examples:

[0059] The small-angle XRD test of the sample was performed on a high-power rotating target X-ray diffractometer D8 ADVANCE of BRUKER AXS Company in Germany, and the scanning range was 0.5-10°.

[0060] The wide-angle XRD test of the sample was performed on an X-ray powder diffractometer X’Pert MPD of Philips Company in the Netherlands, Cu Kα target, and the scanning range was 2θ=5-90°.

[0061] The pore structure parameter analysis of the sample was performed on an adsorption instrument ASAP2020-M+C purchased from 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.

[0062] The elemental analysis experiment of the sample was performed on an energy dispersive X-ray fluorescence spectrometer Eagle III produced by EDAX Company in the United States.

[0063] The drying oven was produced by Shanghai Yiheng Scientific Instrument Co., Ltd., and the model was DHG-9030A.

[0064] The muffle furnace was produced by CARBOLITE Company, and the model was CWF1100.

[0065] The ZSM-22 zeolite molecular sieve with a SiO2 / Al2O3 molar ratio of 42 used in the examples and comparative examples was purchased from Tianjin Nanhua Catalyst Co., Ltd.; the ZSM-22 zeolite molecular sieve with a SiO2 / Al2O3 molar ratio of 60 was purchased from Nanjing Jicang Nanometer Technology Co., Ltd.; the pseudo-boehmite powder with a model of SB was purchased from Beijing Yataoohua Chemical Auxiliary Co., Ltd.; the pseudo-boehmite powder with a model of P-DF-09-LSi was purchased from Shandong Aluminum Industry Co., Ltd.; the macroporous pseudo-boehmite powder with a model of PB-0101 was purchased from Zibo Hengqi Powder New Material Co., Ltd. The other reagents used in the examples and comparative examples were purchased from National Pharmaceutical Group Chemical Reagent Co., Ltd., and the reagent purity was analytical pure.

[0066] Example 1

[0067] This example is to illustrate the preparation of the shaped cracking catalyst of the present application.

[0068] (1) Preparation of modified ZSM-22 zeolite

[0069] 2.6 g of magnesium nitrate hexahydrate was dissolved in 100 g of distilled water to prepare a modified component aqueous solution. 9.6 g of ZSM-22 zeolite molecular sieve (SiO2 / Al2O3 = 42, purchased from Tianjin Nanhua Catalyst Co., Ltd.) was added to the above modified component aqueous solution, and after stirring at 60 ℃ for 5 h, water was removed using a rotary evaporator, the solid product was dried at 110 ℃ for 8 h, and then calcined at 550 ℃ for 6 h to obtain modified ZSM-22 zeolite A.

[0070] Based on the total weight of the modified ZSM-22 zeolite A, the content of the ZSM-22 zeolite molecular sieve was 96.0 wt%, and the content of the modified oxide (magnesium oxide) was 4.0 wt%.

[0071] Figure 1 is the wide-angle X-ray diffraction (XRD) spectrum of the modified ZSM-22 zeolite A of Example 1. The spectrum shows that the x-ray diffraction angles of the sample are mainly: 2θ = 8.2°, 20.3°, 24.3°, 24.6° and 25.7°. These five diffraction signals are consistent with the diffraction spectrum of the ZSM-22 zeolite molecular sieve with TON topological framework structure, indicating that the ZSM-22 zeolite crystal phase did not change significantly during the preparation of the catalyst. In addition, there is no diffraction signal corresponding to the modified oxide in the wide-angle XRD spectrum, indicating that the modified component is in a uniform dispersed state on the catalyst.

[0072] (2) Preparation of MCM-41 all-silicon mesoporous molecular sieve

[0073] Mix 55 g of 25% tetramethylammonium hydroxide, 218 g of cetyltrimethylammonium bromide and 900 g of deionized water, and stir at room temperature for 30 minutes; add 304 g of tetramethyl orthosilicate to the mixture, and stir for 1 hour; then transfer the mixture to an autoclave, and hydrothermally crystallize at 70°C for 72 hours. After the hydrothermal reaction, separate the solid product from the mother liquor, and wash with deionized water until neutral. Dry the solid product at 70°C under reduced pressure for 5 hours, and then calcine at 550°C for 8 hours to obtain MCM-41 full-silica mesoporous molecular sieve A.

[0074] The specific surface area of the MCM-41 full-silica mesoporous molecular sieve A is 1081 m 2 / g, the pore volume is 1.2 cm 3 / g, and the average pore size is 2.6 nm.

[0075] Figure 2 The small-angle XRD pattern of the MCM-41 full-silica mesoporous molecular sieve A is shown. The XRD pattern has a very strong diffraction peak near 2θ = 2°, and three weaker peaks near 2θ = 4°, 4.5° and 6°. The four distinguishable diffraction peaks correspond to the (100), (110), (200) and (210) crystal planes, respectively, indicating that the sample has a typical MCM-41 type hexagonal mesoporous structure, and the long-range ordered structure has high regularity.

[0076] (3) Preparation of a shaped pyrolysis catalyst

[0077] Mix 53 g of modified ZSM-22 molecular sieve A, 35 g of MCM-41 full-silica mesoporous molecular sieve A, 17 g of pseudoboehmite with a type of P-DF-09-L Si and 8 g of cellulose, and then add 45 g of 8% dilute acetic acid. Stir until uniform, and then extrude and shape. Dry at 120°C for 7 hours, and then calcine at 560°C for 10 hours to obtain a shaped pyrolysis catalyst A.

[0078] Based on the total weight of the catalyst A, the content of the modified ZSM-22 molecular sieve is 53% by weight, the content of the MCM-41 full-silica mesoporous molecular sieve is 35% by weight, and the content of the binding oxide (alumina) is 12% by weight.

[0079] The specific surface area of the catalyst A is 516 m 2 / g, the pore volume is 0.62 cm 3 / g.

[0080] (4) Performance evaluation of direct conversion of waste plastics to low-carbon olefins

[0081] The methyl tert-butyl ether catalytic cracking reaction performance of the catalyst was evaluated on a fixed bed reaction device. The catalyst loading was 10.0 g, the polyethylene waste plastic loading was 50.0 g, the reaction temperature was 480°C, the reaction pressure was 0.1 MPa, and the reaction time was 2 hours. After the product was cooled and gas-liquid separation, the gas composition was analyzed by Agilent 6890 gas chromatograph equipped with an Al2O3-S capillary column and a hydrogen flame detector (FID), and the quantitative analysis was performed by using a correction factor with programmed temperature. The liquid composition was analyzed by Agilent 6890 gas chromatograph equipped with a PONA column. The reaction results are shown in Table 1.

[0082] Example 2

[0083] This example is to illustrate the preparation of the shaped cracking catalyst of the present application.

[0084] (1) Preparation of modified ZSM-22 molecular sieve

[0085] 0.8 g of sodium nitrate was dissolved in 80 g of distilled water to prepare a modified component aqueous solution. 9.7 g of ZSM-22 zeolite molecular sieve (SiO2 / Al2O3=60, purchased from Nanjing Jicang Nanometer Technology Co., Ltd.) was added to the above modified component aqueous solution, and after stirring at 80°C for 2 h, water was removed using a rotary evaporator, the solid product was dried at 130°C for 3 h, and then calcined at 600°C for 3 h to obtain modified ZSM-22 molecular sieve B.

[0086] Based on the total weight of the modified ZSM-22 molecular sieve B, the content of ZSM-22 zeolite molecular sieve was 97.0% by weight, and the content of modified oxide (sodium oxide) was 3.0% by weight.

[0087] (2) Preparation of MCM-41 all-silicon mesoporous molecular sieve

[0088] 126 g of tetramethylammonium hydroxide, 73 g of cetyltrimethylammonium bromide, and 360 g of deionized water were mixed and stirred at room temperature for 30 minutes; 417 g of tetraethyl orthosilicate was added to the mixture, and after stirring for 1 hour, the mixture was transferred to an autoclave and crystallized at 30°C for 120 hours. Then the solid product was separated from the mother liquor and washed with deionized water until neutral. The solid product was dried at 50°C under reduced pressure for 10 hours, and then calcined at 500°C for 12 hours to obtain MCM-41 all-silicon mesoporous molecular sieve B.

[0089] The specific surface area of MCM-41 all-silicon mesoporous molecular sieve B was 1137 m 2 / g, the pore volume was 1.3 cm 3 / g, and the average pore size was 2.7 nm.

[0090] (3) Preparation of shaped cracking catalyst

[0091] The 50 g modified ZSM-22 molecular sieve B, 40 g MCM-41 full-silica mesoporous molecular sieve B, 14 g pseudoboehmite with model number SB and 6 g sesbania grandiflora powder are mixed uniformly, 48 g of 3% dilute nitric acid is added, and after stirring uniformly, extrusion molding is performed; drying at 130°C for 6 hours, and finally calcining at 500°C for 16 hours to obtain a shaped cracking catalyst B.

[0092] The content of the modified ZSM-22 molecular sieve is 50% by weight, the content of the MCM-41 full-silica mesoporous molecular sieve is 40% by weight, and the content of the bound oxide (alumina) is 10% by weight, based on the total weight of the catalyst B.

[0093] The specific surface area of the catalyst B is 558 m 2 / g, and the pore volume is 0.65 cm 3 / g.

[0094] The reaction performance of the catalyst B is tested according to the method for evaluating the reaction performance of the catalyst for directly converting waste plastics into low-carbon olefins in step (4) in Example 1, and the evaluation results are listed in Table 1.

[0095] Example 3

[0096] This example is directed to a shaped cracking catalyst prepared by the present application.

[0097] (1) Preparation of modified ZSM-22 molecular sieve

[0098] 0.9 g of barium nitrate is dissolved in 150 g of distilled water to prepare a modified component aqueous solution. 9.5 g of ZSM-22 zeolite molecular sieve (SiO2 / Al2O3 = 42, purchased from Tianjin Nanhua Catalyst Co., Ltd.) is added to the above modified component aqueous solution, and after stirring at 30°C for 20 h, water is removed using a rotary evaporator, the solid product is dried at 80°C for 20 h, and then calcined at 500°C for 10 h to obtain a modified ZSM-22 molecular sieve C.

[0099] The content of the ZSM-22 zeolite molecular sieve is 95.0% by weight, and the content of the modified oxide (barium oxide) is 5.0% by weight, based on the total weight of the modified ZSM-22 molecular sieve C.

[0100] (2) Preparation of MCM-41 full-silica mesoporous molecular sieve

[0101] Mix 18 g of tetramethylammonium hydroxide, 510 g of cetyltrimethylammonium bromide and 1800 g of deionized water, and stir at room temperature for 30 minutes; add 304 g of tetraethyl orthosilicate to the mixture, and stir for 1 hour; then transfer the mixture to an autoclave, and crystallize at 120°C for 5 hours. Then separate the solid product from the mother liquor, and wash with deionized water until neutral. Dry the solid product at 90°C under reduced pressure for 2 hours, and then calcine at 600°C for 3 hours to obtain MCM-41 full-silica mesoporous molecular sieve C.

[0102] The specific surface area of the MCM-41 full-silica mesoporous molecular sieve C is 1018 m 2 / g, the pore volume is 1.0 cm 3 / g, and the average pore diameter is 2.4 nm.

[0103] (3) Preparation of the shaped pyrolysis catalyst

[0104] Mix 55 g of modified ZSM-22 molecular sieve C, 30 g of MCM-41 full-silica mesoporous molecular sieve C, 21 g of macroporous pseudoboehmite powder with model number PB-0101, and 10 g of sesbania powder, and then add 42 g of 10% dilute nitric acid. Stir until uniform, and then extrude into a shape. Dry at 100°C for 12 hours, and then calcine at 600°C for 5 hours to obtain the shaped pyrolysis catalyst C.

[0105] The content of the modified ZSM-22 molecular sieve is 55% by weight, the content of the MCM-41 full-silica mesoporous molecular sieve is 30% by weight, and the content of the binding oxide (alumina) is 15% by weight, based on the total weight of the catalyst C.

[0106] The specific surface area of the catalyst C is 471 m 2 / g, the pore volume is 0.58 cm 3 / g.

[0107] The reaction performance of the 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 (4) of Example 1, and the evaluation results are listed in Table 1.

[0108] Example 4

[0109] This example is directed to the shaped pyrolysis catalyst prepared according to the present application.

[0110] (1) Preparation of the modified ZSM-22 molecular sieve

[0111] A modified component aqueous solution was prepared by dissolving 0.8 g of calcium nitrate in 120 g of distilled water. 9.7 g of ZSM-22 zeolite molecular sieve (SiO2 / Al2O3=42, purchased from Tianjin Nanhua Catalyst Co., Ltd.) was added to the above modified component aqueous solution, and after stirring at 60°C for 5 h, water was removed using a rotary evaporator, the solid product was dried at 110°C for 8 h, and then calcined at 550°C for 6 h to obtain modified ZSM-22 molecular sieve D.

[0112] The content of ZSM-22 zeolite molecular sieve was 97.5% by weight, and the content of modified oxide (calcium oxide) was 2.5% by weight, based on the total weight of modified ZSM-22 molecular sieve D.

[0113] (2) Preparation of MCM-41 all-silicon mesoporous molecular sieve

[0114] MCM-41 all-silicon mesoporous molecular sieve A was prepared according to the method of step (2) in Example 1.

[0115] (3) Preparation of shaped pyrolysis catalyst

[0116] After 47 g of modified ZSM-22 molecular sieve D, 45 g of MCM-41 all-silicon mesoporous molecular sieve A, 11 g of pseudoboehmite with a type of P-DF-09-LSi, and 5 g of cellulose were uniformly mixed, 50 g of 8% dilute acetic acid was added, and after uniform stirring, extrusion molding was performed; drying was performed at 120°C for 7 hours, and finally calcination was performed at 560°C for 10 hours to obtain shaped pyrolysis catalyst D.

[0117] The content of modified ZSM-22 molecular sieve was 47% by weight, the content of MCM-41 all-silicon mesoporous molecular sieve was 45% by weight, and the content of binding oxide (alumina) was 8% by weight, based on the total weight of catalyst D.

[0118] The specific surface area of catalyst D was 602 m 2 / g, and the pore volume was 0.68 cm 3 / g.

[0119] The reaction performance of catalyst D was tested according to the method for evaluating the reaction performance of direct conversion of waste plastics to light olefins in Example 1, and the evaluation results are shown in Table 1.

[0120] Example 5

[0121] This example is to illustrate the shaped pyrolysis catalyst prepared by the present application.

[0122] (1) Preparation of modified ZSM-22 molecular sieve

[0123] A modified component aqueous solution was prepared by dissolving 1.2 g of strontium nitrate in 100 g of distilled water. 9.4 g of ZSM-22 zeolite molecular sieve (SiO2 / Al2O3=60, purchased from Nanjing Jicang Nanometer Technology Co., Ltd.) was added to the above modified component aqueous solution, and after stirring at 80℃ for 2 h, water was removed using a rotary evaporator, the solid product was dried at 130℃ for 3 h, and then calcined at 600℃ for 3 h to obtain modified ZSM-22 molecular sieve E.

[0124] The content of ZSM-22 zeolite molecular sieve was 94.0% by weight, and the content of strontium oxide was 6.0% by weight, based on the total weight of the modified ZSM-22 molecular sieve E.

[0125] (2) Preparation of MCM-41 all-silicon mesoporous molecular sieve

[0126] MCM-41 all-silicon mesoporous molecular sieve B was prepared according to the method of step (2) in Example 2.

[0127] (3) Preparation of shaped pyrolysis catalyst

[0128] After 58 g of modified ZSM-22 molecular sieve E, 24 g of MCM-41 all-silicon mesoporous molecular sieve B, 25 g of pseudoboehmite with a type of SB, and 12 g of sesbania powder were uniformly mixed, 42 g of 3% dilute nitric acid was added, and after being uniformly stirred, it was extruded into a shape; dried at 130℃ for 6 hours, and finally calcined at 500℃ for 16 hours to obtain a shaped pyrolysis catalyst E.

[0129] The content of modified ZSM-22 molecular sieve was 58% by weight, the content of MCM-41 all-silicon mesoporous molecular sieve was 24% by weight, and the content of binding oxide (alumina) was 18% by weight, based on the total weight of the catalyst E.

[0130] The specific surface area of the catalyst E was 419 m 2 / g, and the pore volume was 0.55 cm 3 / g.

[0131] The reaction performance of the catalyst E was tested according to the method for evaluating the reaction performance of direct conversion of waste plastics to light olefins in step (4) in Example 1, and the evaluation results are shown in Table 1.

[0132] Example 6

[0133] This example is to illustrate the shaped pyrolysis catalyst prepared by the present application.

[0134] (1) Preparation of modified ZSM-22 molecular sieve

[0135] A modified component aqueous solution was prepared by dissolving 0.4 g of potassium nitrate in 120 g of distilled water. 9.8 g of ZSM-22 zeolite molecular sieve (SiO2 / Al2O3= 42, purchased from Tianjin Nanhua Catalyst Co., Ltd.) was added to the above modified component aqueous solution, and after stirring at 60°C for 5 h, water was removed using a rotary evaporator, the solid product was dried at 110°C for 8 h, and then calcined at 550°C for 6 h to obtain modified ZSM-22 molecular sieve F.

[0136] The content of ZSM-22 zeolite molecular sieve was 98.0% by weight, and the content of modified oxide (potassium oxide) was 2.0% by weight, based on the total weight of modified ZSM-22 molecular sieve F.

[0137] (2) Preparation of MCM-41 all-silicon mesoporous molecular sieve

[0138] MCM-41 all-silicon mesoporous molecular sieve A was prepared according to the method of step (2) in Example 1.

[0139] (3) Preparation of shaped pyrolysis catalyst

[0140] After 44 g of modified ZSM-22 molecular sieve F, 50 g of MCM-41 all-silicon mesoporous molecular sieve A, 8 g of pseudoboehmite with a type of P-DF-09-LSi, and 4 g of cellulose were uniformly mixed, 54 g of 2% dilute acetic acid was added, and after uniform stirring, extrusion molding was performed; drying was performed at 120°C for 7 hours, and finally calcination was performed at 560°C for 10 hours to obtain shaped pyrolysis catalyst F.

[0141] The content of modified ZSM-22 molecular sieve was 44% by weight, the content of MCM-41 all-silicon mesoporous molecular sieve was 50% by weight, and the content of binding oxide (alumina) was 6% by weight, based on the total weight of catalyst F.

[0142] The specific surface area of catalyst F was 646 m 2 / g, and the pore volume was 0.72 cm 3 / g.

[0143] The reaction performance of catalyst F was tested according to the method for evaluating the reaction performance of direct conversion of waste plastics to light olefins in Example 1, step (4), and the evaluation results are shown in Table 1.

[0144] Example 7

[0145] This example is intended to illustrate the shaped pyrolysis catalyst prepared by the present application.

[0146] (1) Preparation of modified ZSM-22 molecular sieve

[0147] A modified component aqueous solution was prepared by dissolving 2.1 g of calcium nitrate in 100 g of distilled water. 9.3 g of ZSM-22 zeolite molecular sieve (SiO2 / Al2O3=60, purchased from Nanjing Jicang Nanometer Technology Co., Ltd.) was added to the above modified component aqueous solution, and after stirring at 80°C for 2 h, water was removed using a rotary evaporator, the solid product was dried at 130°C for 3 h, and then calcined at 600°C for 3 h to obtain modified ZSM-22 molecular sieve G.

[0148] The content of ZSM-22 zeolite molecular sieve was 93.0% by weight, and the content of modified oxide (calcium oxide) was 7.0% by weight, based on the total weight of the modified ZSM-22 molecular sieve G.

[0149] (2) Preparation of MCM-41 all-silicon mesoporous molecular sieve

[0150] MCM-41 all-silicon mesoporous molecular sieve B was prepared according to the method of step (2) in Example 2.

[0151] (3) Preparation of shaped pyrolysis catalyst

[0152] After 60 g of modified ZSM-22 molecular sieve G, 20 g of MCM-41 all-silicon mesoporous molecular sieve B, 28 g of pseudoboehmite with a type of SB, and 14 g of sesbania powder were uniformly mixed, 40 g of 12% dilute nitric acid was added, and after stirring uniformly, it was extruded into a shape; dried at 130°C for 6 hours, and finally calcined at 500°C for 16 hours to obtain a shaped pyrolysis catalyst G.

[0153] The content of modified ZSM-22 molecular sieve was 60% by weight, the content of MCM-41 all-silicon mesoporous molecular sieve was 20% by weight, and the content of binding oxide (alumina) was 20% by weight, based on the total weight of the catalyst G.

[0154] The specific surface area of the catalyst G was 384 m 2 / g, and the pore volume was 0.52 cm 3 / g.

[0155] The reaction performance of the catalyst G was tested according to the method for evaluating the reaction performance of direct conversion of waste plastics to light olefins in step (4) of Example 1, and the evaluation results are listed in Table 1.

[0156] Comparative Example 1

[0157] (1) Preparation of modified ZSM-22 molecular sieve

[0158] A modified component aqueous solution was prepared by dissolving 0.3 g of sodium nitrate in 120 g of distilled water. 9.9 g of ZSM-22 zeolite molecular sieve (SiO2 / Al2O3= 42, purchased from Tianjin Nanhua Catalyst Co., Ltd.) was added to the above modified component aqueous solution, and after stirring at 60°C for 5 h, water was removed using a rotary evaporator, the solid product was dried at 110°C for 8 h, and then calcined at 550°C for 6 h to obtain modified ZSM-22 molecular sieve D1.

[0159] The content of ZSM-22 zeolite molecular sieve was 99% by weight, and the content of sodium oxide was 1% by weight, based on the total weight of the modified ZSM-22 molecular sieve D1.

[0160] (2) Preparation of MCM-41 all-silica mesoporous molecular sieve

[0161] MCM-41 all-silica mesoporous molecular sieve A was prepared according to the method of step (2) in Example 1.

[0162] (3) Preparation of shaped pyrolysis catalyst

[0163] After 24 g of modified ZSM-22 molecular sieve D1, 69 g of MCM-41 all-silica mesoporous molecular sieve A, 10 g of pseudoboehmite with a type of P-DF-09-LSi, and 15 g of cellulose were uniformly mixed, 58 g of 1% dilute acetic acid was added, and after uniform stirring, extrusion molding was performed; drying was performed at 120°C for 7 hours, and finally calcination was performed at 560°C for 10 hours to obtain shaped pyrolysis catalyst D1.

[0164] The content of modified ZSM-22 molecular sieve was 24% by weight, the content of MCM-41 all-silica mesoporous molecular sieve was 69% by weight, and the content of binding oxide (alumina) was 7% by weight, based on the total weight of catalyst D1.

[0165] The specific surface area of catalyst D1 was 802 m 2 / g, and the pore volume was 0.85 cm 3 / g.

[0166] The reaction performance of catalyst D1 was tested according to the method for evaluating the reaction performance of direct conversion of waste plastics to light olefins in Example 1, step (4), and the evaluation results are shown in Table 1.

[0167] Comparative Example 2

[0168] (1) Preparation of modified ZSM-22 molecular sieve

[0169] A modified component aqueous solution was prepared by dissolving 6.4 g of magnesium nitrate hexahydrate in 100 g of distilled water. 9.0 g of ZSM-22 zeolite molecular sieve (SiO2 / Al2O3=60, purchased from Nanjing Jicang Nanometer Technology Co., Ltd.) was added to the above modified component aqueous solution, and after stirring at 80°C for 2 h, water was removed using a rotary evaporator, the solid product was dried at 130°C for 3 h, and then calcined at 600°C for 3 h to obtain modified ZSM-22 molecular sieve D2.

[0170] The content of ZSM-22 zeolite molecular sieve was 90% by weight, and the content of magnesium oxide was 10% by weight, based on the total weight of the modified ZSM-22 molecular sieve D2.

[0171] (2) Preparation of MCM-41 all-silica mesoporous molecular sieve

[0172] MCM-41 all-silica mesoporous molecular sieve B was prepared according to the method of step (2) in Example 2.

[0173] (3) Preparation of shaped pyrolysis catalyst

[0174] After 75 g of modified ZSM-22 molecular sieve D2, 10 g of MCM-41 all-silica mesoporous molecular sieve B, 21 g of pseudoboehmite with a type of SB, and 3 g of sesbania powder were uniformly mixed, 40 g of 15% dilute nitric acid was added, and after uniform stirring, it was extruded into a shape; dried at 130°C for 6 hours, and finally calcined at 500°C for 16 hours to obtain a shaped pyrolysis catalyst D2.

[0175] The content of modified ZSM-22 molecular sieve was 75% by weight, the content of MCM-41 all-silica mesoporous molecular sieve was 10% by weight, and the content of bound oxide (alumina) was 15% by weight, based on the total weight of the catalyst D2.

[0176] The specific surface area of the catalyst D2 was 287 m 2 / g, and the pore volume was 0.42 cm 3 / g.

[0177] The reaction performance of the catalyst D2 was tested according to the method for evaluating the reaction performance of direct conversion of waste plastics to light olefins in step (4) of Example 1, and the evaluation results are listed in Table 1.

[0178] Comparative Example 3

[0179] Step (1) in Example 1 was cancelled.

[0180] MCM-41 all-silica mesoporous molecular sieve A was prepared according to the method of step (2) in Example 1.

[0181] (3) Preparation of shaped pyrolysis catalyst

[0182] 88 g of MCM-41 full-silica mesoporous molecular sieve A, 17 g of pseudoboehmite with a model number of P-DF-09-LSi, and 10 g of cellulose were mixed uniformly, 60 g of 3% dilute acetic acid was added, and after stirring uniformly, extrusion molding was performed; drying was performed at 120°C for 7 hours, and finally calcination was performed at 560°C for 10 hours, thereby obtaining a molded pyrolysis catalyst D3.

[0183] The content of the MCM-41 full-silica mesoporous molecular sieve was 88% by weight, and the content of the bound oxide (alumina) was 12% by weight, based on the total weight of the catalyst D3.

[0184] The specific surface area of the catalyst D3 was 923 m2 / g, and the pore volume was 0.91 cm3 / g.

[0185] The reaction performance of the catalyst D3 was tested according to the method for evaluating the reaction performance of direct conversion of waste plastics to light olefins according to step (4) in Example 1, and the evaluation results are shown in Table 1.

[0186] Comparative Example 4

[0187] (1) Preparation of modified ZSM-22 molecular sieve

[0188] 2.1 g of barium nitrate was dissolved in 100 g of distilled water to prepare a modified component aqueous solution. 8.8 g of ZSM-22 zeolite molecular sieve (SiO2 / Al2O3 = 60, purchased from Nanjing Jicang Nanometer Technology Co., Ltd.) was added to the above modified component aqueous solution, and after stirring at 80°C for 2 h, water was removed using a rotary evaporator, the solid product was dried at 130°C for 3 h, and then calcined at 600°C for 3 h, thereby obtaining a modified ZSM-22 molecular sieve D4.

[0189] The content of the ZSM-22 zeolite molecular sieve was 87.6% by weight, and the content of the barium oxide was 12.4% by weight, based on the total weight of the modified ZSM-22 molecular sieve D4.

[0190] Step (2) in Example 2 was omitted.

[0191] (3) Preparation of molded pyrolysis catalyst

[0192] 85 g of the modified ZSM-22 molecular sieve D4, 21 g of pseudoboehmite with a model number of SB, and 6 g of sesbania powder were mixed uniformly, 40 g of 15% dilute nitric acid was added, and after stirring uniformly, extrusion molding was performed; drying was performed at 130°C for 6 hours, and finally calcination was performed at 500°C for 16 hours, thereby obtaining a molded pyrolysis catalyst D4.

[0193] The content of the modified ZSM-22 molecular sieve was 85% by weight, and the content of the bound oxide (alumina) was 15% by weight, based on the total weight of the catalyst D4.

[0194] The specific surface area of catalyst D4 was 195 m2 / g, and the pore volume was 0.36 cm3 / g. 2 / g, and the pore volume was 0.36 cm3 / g. 3 / g.

[0195] The reaction performance of catalyst D4 was tested according to the reaction performance evaluation method for direct conversion of waste plastics to light olefins in step (4) in Example 1, and the evaluation results are listed in Table 1.

[0196] Comparative Example 5

[0197] Step (1) in Example 1 was cancelled.

[0198] MCM-41 full-silica mesoporous molecular sieve A was prepared according to the method in step (2) in Example 1.

[0199] (3) Preparation of shaped pyrolysis catalyst

[0200] After 53 g of ZSM-22 zeolite molecular sieve (SiO2 / Al2O3=42, purchased from Tianjin Nanhua Catalyst Co., Ltd.), 35 g of MCM-41 full-silica mesoporous molecular sieve A, 17 g of pseudo-boehmite with model number P-DF-09-LSi, and 8 g of cellulose were uniformly mixed, 45 g of 8% dilute acetic acid was added, and after uniform stirring, extrusion molding was performed; drying was performed at 120°C for 7 hours, and finally calcination was performed at 560°C for 10 hours to obtain shaped pyrolysis catalyst D5.

[0201] Based on the total weight of catalyst D5, the content of ZSM-22 zeolite molecular sieve was 53% by weight, the content of MCM-41 full-silica mesoporous molecular sieve was 35% by weight, and the content of binder oxide (alumina) was 12% by weight.

[0202] The reaction performance of catalyst D5 was tested according to the reaction performance evaluation method for direct conversion of waste plastics to light olefins in step (4) in Example 1, and the evaluation results are listed in Table 1.

[0203] Comparative Example 6

[0204] (1) Preparation of modified ZSM-22 molecular sieve

[0205] 1.6 g of nickel nitrate hexahydrate was dissolved in 100 g of distilled water to prepare a modified component aqueous solution. 9.6 g of ZSM-22 zeolite molecular sieve (SiO2 / Al2O3=42, purchased from Tianjin Nanhua Catalyst Co., Ltd.) was added to the above modified component aqueous solution, and after stirring at 60°C for 5 h, water was removed using a rotary evaporator, the solid product was dried at 110°C for 8 h, and then calcined at 550°C for 6 h to obtain modified ZSM-22 molecular sieve D6.

[0206] The content of the ZSM-22 zeolite is 96% by weight and the content of the nickel oxide is 4% by weight, based on the total weight of the modified ZSM-22 molecular sieve D6.

[0207] The MCM-41 full-silica mesoporous molecular sieve A was prepared according to the method of step (2) in Example 1.

[0208] (3) Preparation of the shaped pyrolysis catalyst

[0209] The 53 g of modified ZSM-22 molecular sieve, 35 g of MCM-41 full-silica mesoporous molecular sieve A, 17 g of pseudo-boehmite with a type of P-DF-09-LSi and 8 g of cellulose were mixed uniformly, 45 g of 8% dilute acetic acid was added, and after stirring uniformly, extrusion molding was performed; drying was performed at 120°C for 7 hours, and finally calcination was performed at 560°C for 10 hours to obtain the shaped pyrolysis catalyst D6.

[0210] The content of the modified ZSM-22 molecular sieve is 53% by weight, the content of the MCM-41 full-silica mesoporous molecular sieve is 35% by weight, and the content of the bound oxide (alumina) is 12% by weight, based on the total weight of the catalyst D6.

[0211] The reaction performance of the catalyst D6 was tested according to the method for evaluating the reaction performance of the direct conversion of waste plastics to low-carbon olefins in step (4) in Example 1, and the evaluation results are listed in Table 1.

[0212] Table 1

[0213] Item Catalyst Waste plastic conversion (%) Low carbon olefin yield (%) Example 1 Catalyst A 100 43.7 Example 2 Catalyst B 100 43.5 Example 3 Catalyst C 100 43.4 Example 4 Catalyst D 100 41.9 Example 5 Catalyst E 100 41.7 Example 6 Catalyst F 100 40.3 Example 7 Catalyst G 100 40.1 Comparative Example 1 Catalyst D1 95 18.4 Comparative Example 2 Catalyst D2 100 21.7 Comparative Example 3 Catalyst D3 69 5.1 Comparative Example 4 Catalyst D4 100 22.4 Comparative Example 5 Catalyst D5 100 25.8 Comparative Example 6 Catalyst D6 100 26.4

[0214] As can be seen from the above results, the shaped pyrolysis catalyst provided by the present application can make the direct catalytic conversion of waste plastics to low-carbon olefins. The conversion rate of waste plastics is 100%, and the yield of low-carbon olefins is high.

[0215] In Comparative Example 1, the content of the modified component in the modified ZSM-22 molecular sieve is too low, and the modification effect is poor. In addition, the content of the MCM-41 full-silica mesoporous molecular sieve is too high, and the content of the modified ZSM-22 molecular sieve is too low. Due to the uneven distribution of acid sites on the catalyst and the poor dispersion of active sites in the reaction process, the conversion rate of the raw material is low, and the yield of low-carbon olefins is low.

[0216] In Comparative Example 2, the content of the MCM-41 full-silica mesoporous molecular sieve is too low, the content of the modified ZSM-22 molecular sieve is too high, and the content of the modified component exceeds the scope of the claims. Due to the small number of acid sites on the catalyst and the small number of large-pore channels in the catalyst, the diffusion of reactant and product molecules is hindered in the reaction process, resulting in a low yield of low-carbon olefins.

[0217] In the comparative example 3, the catalyst does not contain the modified ZSM-22 molecular sieve, but only contains the MCM-41 full-silica mesoporous molecular sieve. Due to the fact that the catalyst almost does not contain the acid center, the reason for the serious lack of the activation site in the reaction process, the conversion rate of the raw material is very low, and the yield of the low carbon olefin is low.

[0218] In the comparative example 4, the catalyst does not contain the MCM-41 full-silica mesoporous molecular sieve, but only contains the modified ZSM-22 molecular sieve. Due to the fact that the catalyst almost does not contain the large-pore pore channel, the reason for the serious diffusion hindrance of the reactant and product molecules in the reaction process, the yield of the low carbon olefin is low.

[0219] In the comparative example 5, the catalyst does not contain the modified oxide, and the yield of the low carbon olefin is low.

[0220] In the comparative example 6, the modified oxide specified in the present application is not used, but the nickel oxide is used. Due to the fact that the modified effect of the nickel oxide with the same weight is poor, the yield of the low carbon olefin is low.

[0221] The preferred embodiments of the present application are described in detail above, 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. Use of a shaped pyrolysis catalyst in a direct catalytic pyrolysis of waste plastics to light olefins reaction, said use comprising: The plastic powder is polyethylene waste plastic, and the shaped cracking catalyst comprises a composite carrier and a bound oxide supported on the composite carrier, the composite carrier comprises modified ZSM-22 molecular sieve and MCM-41 full-silicon mesoporous molecular sieve, the modified ZSM-22 molecular sieve comprises ZSM-22 zeolite molecular sieve and modified oxide, the content of the ZSM-22 zeolite molecular sieve is 93-98% by weight based on the total weight of the modified ZSM-22 molecular sieve, and the content of the modified oxide is 2-7% by weight based on the total weight of the modified ZSM-22 molecular sieve, the modified oxide is alkali metal oxide and / or alkaline earth metal oxide, and the content of the modified ZSM-22 molecular sieve is 44-60% by weight based on the total weight of the shaped cracking catalyst, the content of the MCM-41 full-silicon mesoporous molecular sieve is 20-50% by weight based on the total weight of the shaped cracking catalyst, and the content of the bound oxide is 6-20% by weight based on the total weight of the shaped cracking catalyst. The preparation method of the shaped cracking catalyst comprises the following steps: The modified ZSM-22 molecular sieve, the MCM-41 full-silicon mesoporous molecular sieve, a binder and an extrusion aid are mixed and extruded to form a shaped body, and the shaped body is dried and calcined to obtain the shaped cracking catalyst.

2. Use according to claim 1, wherein, The content of the modified ZSM-22 molecular sieve is 47-58% by weight based on the total weight of the shaped cracking catalyst, the content of the MCM-41 full-silicon mesoporous molecular sieve is 24-45% by weight based on the total weight of the shaped cracking catalyst, and the content of the bound oxide is 8-18% by weight based on the total weight of the shaped cracking catalyst.

3. Use according to claim 2, wherein, The content of the modified ZSM-22 molecular sieve is 50-55% by weight based on the total weight of the shaped cracking catalyst, the content of the MCM-41 full-silicon mesoporous molecular sieve is 30-40% by weight based on the total weight of the shaped cracking catalyst, and the content of the bound oxide is 10-15% by weight based on the total weight of the shaped cracking catalyst.

4. The use according to claim 1, wherein, The bound oxide comprises alumina and / or silicon oxide.

5. Use according to claim 4, wherein, The bound oxide is alumina.

6. The use according to any one of claims 1 to 3, wherein The shaped cracking catalyst has a specific surface area of 350-700 m 2 / g, and a pore volume of 0.45-0.8 cm 3 / g; and / or, the specific surface area of the MCM-41 full-silica mesoporous molecular sieve is 900-1300 m 2 / g, and the pore volume is 0.8-1.4 cm 3 / g, and the average pore diameter is 2-4 nm.

7. The use according to claim 1, wherein, The content of the ZSM-22 zeolite molecular sieve is 94-97.5% by weight based on the total weight of the modified ZSM-22 molecular sieve, and the content of the modified oxide is 2.5-6% by weight based on the total weight of the modified ZSM-22 molecular sieve.

8. Use according to claim 7, wherein, The content of the ZSM-22 zeolite molecular sieve is 95-97% by weight based on the total weight of the modified ZSM-22 molecular sieve, and the content of the modified oxide is 3-5% by weight based on the total weight of the modified ZSM-22 molecular sieve.

9. The use according to any one of claims 1 to 3, wherein The SiO2 / Al2O3 molar ratio of the ZSM-22 zeolite molecular sieve is 20-100.

10. Use according to claim 9, wherein, The SiO2 / Al2O3 molar ratio of the ZSM-22 zeolite molecular sieve is 40-60. The modified oxide is selected from one or more of sodium oxide, potassium oxide, calcium oxide, magnesium oxide, strontium oxide and barium oxide.

11. The use according to any one of claims 1 to 3, wherein The preparation method of the modified ZSM-22 molecular sieve comprises the following steps: The ZSM-22 zeolite molecular sieve is mixed with a modified component aqueous solution and subjected to contact reaction, and then subjected to water removal, drying and calcination to obtain the modified ZSM-22 molecular sieve, and the modified component aqueous solution comprises a metal salt and water. And / or, the metal salt is selected from nitrates of one or more of alkali metals and alkaline earth metals. And / or, the mass concentration of the modified component aqueous solution is 0.2-10%. And / or, the weight ratio of the ZSM-22 zeolite molecular sieve to the modified component aqueous solution is 1:(3-30). And / or, the conditions of the contact reaction include: temperature is 10-100℃, time is 0.5-50h. And / or, the conditions of the calcination include: temperature is 400-700℃, time is 2-20h.

12. Use according to claim 11, wherein, The metal salt is selected from nitrates of one or more of sodium, potassium, calcium, magnesium, strontium and barium.

13. The use according to claim 1, wherein, The acidic aqueous solution is selected from one or more of dilute nitric acid, dilute acetic acid, dilute hydrochloric acid, dilute phosphoric acid and dilute sulfuric acid. And / or, the concentration of the acidic aqueous solution is 1-30%. And / or, the binder is selected from one or more of pseudo-boehmite, aluminum hydroxide gel, aluminum sol, gibbsite and bayerite. And / or, the extrusion aid is selected from one or more of cellulose, sesbania powder, polyacrylamide, polyvinyl alcohol, glycerol and polyethylene glycol. And / or, the weight ratio of the modified ZSM-22 molecular sieve, the MCM-41 full-silicon mesoporous molecular sieve, the binder, the extrusion aid and the acidic aqueous solution is 1:(0.2-2.0):(0.1-1.0):(0.05-0.5):(0.3-1.6). And / or, the conditions of the calcination include: temperature is 450-650℃, time is 2-30h.

14. The use according to claim 1, wherein, The acidic aqueous solution is dilute nitric acid or dilute acetic acid.

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

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