Catalyst for preparing low-carbon olefins from waste plastics and preparation method and application thereof

Abstract

The present application relates to the field of catalyst and the field of recycling of polymer materials, and discloses a waste plastic low-carbon olefin catalyst, a preparation method and application thereof.The waste plastic low-carbon olefin catalyst comprises a molding precursor and a modified oxide supported on the molding precursor, the molding precursor comprises MCM-22 zeolite molecular sieve, SBA-15 full-silicon mesoporous molecular sieve and aluminum oxide, and the content of the molding precursor is 90-98 wt% and the content of the modified oxide is 2-10 wt% based on the total weight of the waste plastic low-carbon olefin catalyst.The catalyst of the present application can solve the problem of waste plastic recycling and increase the production of important chemical raw material low-carbon olefin in the reaction of direct conversion of waste plastic into low-carbon olefin.

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 catalyst for producing low-carbon olefins from waste plastics and a preparation method and application thereof. BACKGROUND

[0002] Plastic products 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 human beings 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 waste plastic recycling and utilization 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 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 thermal cracking, it is a catalytic thermal cracking technology, which can not only reduce the cracking temperature, but also improve the product performance. Thermal cracking-catalytic upgrading method is an improvement of catalytic cracking method, which 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 thermal cracking and catalytic cracking methods, but the process is more complex.

[0004] 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. If a large amount of low-carbon olefins is needed, a two-stage thermal cracking-catalytic upgrading method needs to be used.

[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 application aims to overcome the problem of low content of low-carbon olefins in the plastic catalytic cracking reaction product in the prior art, and provides a low-carbon olefin catalyst prepared from waste plastics, a preparation method and application thereof.

[0007] In order to achieve the above-mentioned purpose, the application provides a low-carbon olefin catalyst prepared from waste plastics, wherein the low-carbon olefin catalyst prepared from waste plastics comprises a molding precursor and a modified oxide loaded on the molding precursor, the molding precursor comprises MCM-22 zeolite molecular sieve, SBA-15 full-silicon mesoporous molecular sieve and aluminum oxide, and the content of the molding precursor is 90-98% by weight and the content of the modified oxide is 2-10% by weight based on the total weight of the low-carbon olefin catalyst prepared from waste plastics.

[0008] The application provides a preparation method of a low-carbon olefin catalyst prepared from waste plastics, wherein the preparation method comprises:

[0009] (1) mixing the molding precursor with an aqueous solution of metal salt and performing a first contact reaction, and then performing water removal and first drying treatment to obtain a catalyst intermediate; the molding precursor comprises MCM-22 zeolite molecular sieve, SBA-15 full-silicon mesoporous molecular sieve and aluminum oxide;

[0010] (2) mixing the catalyst intermediate with an acidic aqueous solution and performing a second contact reaction, and then performing water removal, second drying and calcination treatment to obtain the low-carbon olefin catalyst prepared from waste plastics.

[0011] The application provides a low-carbon olefin catalyst prepared from waste plastics prepared by the preparation method.

[0012] The application provides an application of the low-carbon olefin catalyst prepared from waste plastics in a reaction of directly converting waste plastics into low-carbon olefins.

[0013] The application has the following advantages:

[0014] (1) The low-carbon olefin catalyst prepared from waste plastics provided by the application has raw materials that are easy to obtain, a simple preparation method, easy-to-control conditions and good product repeatability.

[0015] (2) The low-carbon olefin catalyst prepared from waste plastics provided by the application comprises zeolite molecular sieve with certain surface acidity and mesoporous material with a large pore size, has stable structure, good high-temperature resistance and helps the diffusion of raw materials and product molecules in the cracking reaction process; in addition, the molding precursor comprises aluminum oxide, and the strength of the sample after molding is good.

[0016] (3) The waste plastic low-carbon olefin catalyst provided by the application can convert waste plastics into low-carbon olefins in one step when used in the reaction of directly converting waste plastics into low-carbon olefins, which is a new method for chemical recycling of waste plastics. It not only solves the problem of waste plastic recycling, but also increases the production of important chemical raw material low-carbon olefin, and has good economic benefits.

[0017] (4) The waste plastic low-carbon olefin 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 converting waste plastics into low-carbon olefins.

[0018] Other features and advantages of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0019] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the specification, and together with the specific embodiments below, serve to explain the application, but do not constitute a limitation on the application. In the drawings:

[0020] Figure 1 is the wide-angle X-ray diffraction (XRD) spectrum of the waste plastic low-carbon olefin catalyst A of Example 1;

[0021] Figure 2 is the small-angle X-ray diffraction (XRD) spectrum of the waste plastic low-carbon olefin catalyst A of Example 1. DETAILED DESCRIPTION

[0022] 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 numerical values need not be a precision as the same is understood in the art. The endpoints of the ranges of values recited are not to be understood as limiting. Without further ado, it is understood that the end points of the ranges can be combined with one another to form one or more new ranges, which are to be considered disclosed herein.

[0023] As described above, the first aspect of the present application provides a waste plastic low-carbon olefin catalyst, wherein the waste plastic low-carbon olefin catalyst comprises a shaped precursor and a modified oxide supported on the shaped precursor, the shaped precursor comprises MCM-22 zeolite molecular sieve, SBA-15 full-silicon mesoporous molecular sieve and aluminum oxide, and the content of the shaped precursor is 90-98% by weight and the content of the modified oxide is 2-10% by weight based on the total weight of the waste plastic low-carbon olefin catalyst.

[0024] 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 the purpose of the present application is to solve this problem. According to the understanding of the physical and chemical properties of the heterogeneous catalyst by the inventors, 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, the zeolite molecular sieve with a stable skeleton structure and a certain acidity is very suitable as the main component of the catalyst for preparing low-carbon olefins from waste plastics. However, because the pore size of the zeolite molecular sieve is small (generally between 0.4-0.7 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 pore, which not only affects the contact between the reactants and the 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. For example, the MCM-22 zeolite molecular sieve has two independent and unconnected pore structures, the intra-layer pore is a 10-membered ring two-dimensional sinusoidal pore with a pore size of 0.4x0.6 nm; the inter-layer pore is a 12-membered ring supercage with a pore size of 0.7x0.8 nm; and the supercage opening is a 10-membered ring with a pore size of 0.4x0.5 nm. Compared with the zeolite molecular sieve, the SBA-15 full-silicon mesoporous molecular sieve material has a large pore size and a large pore volume, and is very suitable for catalytic reactions involving large molecules. However, the surface acidity of the full-silicon mesoporous molecular sieve material is extremely weak, and it is not suitable for being used alone as a catalyst for cracking waste plastics. The inventors of the present application found that if the structural advantages of the full-silicon mesoporous inorganic material and the surface acid center of the zeolite molecular sieve are comprehensively utilized, a certain amount of SBA-15 full-silicon mesoporous molecular sieve is mixed with the MCM-22 zeolite molecular sieve and modified, and is used as the main component of the catalyst for the cracking reaction of waste plastics, the activity of the catalyst for preparing low-carbon olefins from waste plastics can be effectively improved, and the selectivity of low-carbon olefins can also be increased.

[0025] According to the present application, preferably, the content of the shaped precursor is 92-97 wt%, and the content of the modified oxide is 3-8 wt%, based on the total weight of the catalyst for preparing low-carbon olefins from waste plastics; more preferably, the content of the shaped precursor is 93-96 wt%, and the content of the modified oxide is 4-7 wt%, based on the total weight of the catalyst for preparing low-carbon olefins from waste plastics. In the present application, the use of the specific content of each component can make the catalyst for preparing low-carbon olefins from waste plastics have better catalytic activity and higher selectivity of low-carbon olefins when used in the reaction of directly converting waste plastics to prepare low-carbon olefins.

[0026] According to the present application, the content of the MCM-22 zeolite molecular sieve is 34-55 wt%, the content of the SBA-15 full-silica mesoporous molecular sieve is 27-58 wt%, and the content of the alumina is 8-18 wt%, based on the total weight of the shaped precursor; preferably, the content of the MCM-22 zeolite molecular sieve is 37-51 wt%, the content of the SBA-15 full-silica mesoporous molecular sieve is 34-53 wt%, and the content of the alumina is 10-15 wt%, based on the total weight of the shaped precursor; more preferably, the content of the MCM-22 zeolite molecular sieve is 41-48 wt%, the content of the SBA-15 full-silica mesoporous molecular sieve is 40-45 wt%, and the content of the alumina is 12-14 wt%, based on the total weight of the shaped precursor. In the present application, the use of the specific content of each component can make the prepared waste plastic low-carbon olefin catalyst have better catalytic activity and higher low-carbon olefin selectivity in the reaction of directly converting waste plastics to prepare low-carbon olefins.

[0027] According to the present application, the specific surface area of the MCM-22 zeolite molecular sieve is 400-600 m 2 / g, and the pore volume is 0.4-0.7 cm 3 / g; preferably, the specific surface area of the MCM-22 zeolite molecular sieve is 450-500 m 2 / g, and the pore volume is 0.5-0.6 cm 3 / g. In the present application, the MCM-22 zeolite molecular sieve can be a MCM-22 molecular sieve of model NKF-10 from the Catalyst Factory of Nankai University (molar ratio of silicon to aluminum SiO2 / Al2O3 is 30, specific surface area is 472 m 2 / g, and pore volume is 0.5 cm 3 / g).

[0028] According to the present application, the specific surface area of the SBA-15 full-silica mesoporous molecular sieve is 650-1100 m 2 / g; the pore size (average pore diameter) is 5-8 nm, and the pore volume is 1.2-1.6 cm 3 / g; preferably, the specific surface area of the SBA-15 full-silica mesoporous molecular sieve is 892-967 m 2 / g; the pore size (average pore diameter) is 6.4-7 nm, and the pore volume is 1.2-1.4 cm 3 / g. In the present application, the SBA-15 full-silicon mesoporous molecular sieve with the aforementioned specific parameters can make the prepared waste plastic low-carbon olefin catalyst have better catalytic activity and higher selectivity in the reaction of directly converting waste plastics to prepare low-carbon olefins. In the present application, the SBA-15 full-silicon mesoporous molecular sieve can be prepared by a conventional method, or the SBA-15 full-silicon mesoporous molecular sieve can be prepared by the following steps:

[0029] (a) mixing a template solvent, a silicon source and dilute hydrochloric acid to prepare a gel mixture under hydrolysis gel preparation conditions;

[0030] (b) performing crystallization treatment on the gel mixture.

[0031] (c) performing solid-liquid separation, washing, drying and calcination treatment on the product after the crystallization treatment to obtain the SBA-15 full-silicon mesoporous molecular sieve.

[0032] Specifically, under the hydrolysis gel preparation conditions, the template agent, the silicon source and the dilute hydrochloric acid are mixed to obtain a gel mixture; wherein the concentration of the dilute hydrochloric acid is 1-2 mol / L; then the gel mixture is transferred to a polytetrafluoroethylene-lined reaction kettle, and crystallized at 80-120℃ for 10-40 hours; the product after the crystallization treatment is separated, washed with deionized water, and then the solid product after the crystallization is dried in air at 70-120℃ for 3-10 hours, and calcined at 450-650℃ for 3-12 hours to obtain the full-silicon SBA-15 mesoporous molecular sieve.

[0033] In the preparation method of the SBA-15 full-silicon mesoporous molecular sieve described above, the weight ratio of the template agent: the silicon source: the dilute hydrochloric acid is 1:(0.5-5.0):(5-100), preferably 1:(1.5-2.5):(15-50).

[0034] In the preparation method of the SBA-15 full-silicon mesoporous molecular sieve described above, a conventional template agent used for synthesizing SBA-15 molecular sieve can be used, for example, it can be a non-ionic surfactant, and preferably the template agent is a polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer; wherein the general formula of the template agent is EO a PO b EO a , wherein the value of a is 5-140, the value of b is 30-100, EO is the abbreviation of ethylene oxide, and PO is the abbreviation of propylene oxide; and particularly preferably P123 (EO 20 PO 70 EO 20 ). In addition, it should be noted that P123 is a commercial brand, which can be purchased from Sigma-Aldrich Chemistry Company.

[0035] In the preparation method of the SBA-15 full-silicon mesoporous molecular sieve, the silicon source is an organic silicon source and / or an inorganic silicon source, wherein the organic silicon source is an organic silicate, preferably methyl orthosilicate and / or ethyl orthosilicate; and the inorganic silicon source is one or more of inorganic silicon-containing compounds, preferably water glass, sodium metasilicate and silica sol.

[0036] In the preparation method of the SBA-15 full-silicon mesoporous molecular sieve, the hydrolysis and gelation conditions are not particularly required, and preferably, the hydrolysis and gelation conditions include a hydrolysis temperature of 20-60°C, more preferably 30-50°C, and a hydrolysis time of 12-36 hours, more preferably 18-30 hours.

[0037] In the preparation method of the SBA-15 full-silicon mesoporous molecular sieve, the crystallization conditions include a temperature of 80-120°C and a time of 10-40h.

[0038] In the preparation method of the SBA-15 full-silicon mesoporous molecular sieve, the solid-liquid phase separation process is not particularly required, and can be a separation mode 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 to perform vacuum suction on the bottom side of a funnel or using a centrifugal filter to perform filtration.

[0039] In the preparation method of the SBA-15 full-silicon mesoporous molecular sieve, the method for washing the solid product is not particularly required, for example, the solid product can be washed with deionized water, and the volume ratio of the deionized water to the solid product can be 5-20, and the washing times can be 2-8 times.

[0040] In the preparation method of the SBA-15 full-silicon mesoporous molecular sieve, the drying conditions include a temperature of 60-150°C, preferably 70-120°C, and a time of 2-30h, preferably 3-10h.

[0041] In the preparation method of the SBA-15 full-silicon mesoporous molecular sieve, the calcination treatment conditions can be a temperature of 400-700°C, preferably 450-650°C, and a time of 2-40h, preferably 3-12h.

[0042] According to the present application, the preparation method of the shaped precursor includes: mixing MCM-22 zeolite molecular sieve, full-silicon SBA-15 mesoporous molecular sieve, alumina precursor and extrusion aid in the presence of an acidic aqueous solution to perform extrusion molding, and then performing drying and calcination treatment to obtain a shaped precursor.

[0043] In the preparation method of the shaped precursor, the acidic aqueous solution is selected from one or more of dilute nitric acid, dilute hydrochloric acid, dilute phosphoric acid and dilute sulfuric acid, and preferably is dilute nitric acid; the concentration of the acidic aqueous solution can be 1-30%, and preferably is 2-15%.

[0044] In the preparation method of the shaped precursor, the alumina precursor is selected from one or more of pseudoboehmite, aluminum hydroxide gel, aluminum sol, gibbsite and bayerite; and preferably is pseudoboehmite. In the present application, the pseudoboehmite can be obtained by commercial purchase or preparation. In particular, the pseudoboehmite includes one or more of SB type German original imported pseudoboehmite powder (purchased from Beijing Asia Pacific Owhua Chemical Auxiliary Co., Ltd., with a specific surface area of 241 m 2 / g and 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 and 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 and a pore volume of 1.02 cm 3 / g).

[0045] In the preparation method of the shaped precursor, the extrusion aid is selected from one or more of cellulose, sesbania powder, polyacrylamide, polyvinyl alcohol, glycerol and polyethylene glycol, and preferably is cellulose or sesbania powder.

[0046] In the preparation method of the shaped precursor, the weight ratio of the MCM-22 molecular sieve, the all-silicon SBA-15 mesoporous molecular sieve, the alumina precursor, the extrusion aid and the acidic aqueous solution is 1:(0.4-2.0):(0.2-0.6):(0.02-0.16):(0.8-1.6), and preferably is 1:(0.6-1.5):(0.3-0.5):(0.04-0.12):(1.0-1.4).

[0047] In the preparation method of the shaped precursor, the drying condition includes a temperature of 60-140°C and a time of 5-20h.

[0048] In the preparation method of the shaped precursor, the calcination condition includes a temperature of 450-650°C, and preferably 500-600°C; and a time of 2-30h, and preferably 5-16h.

[0049] According to the present application, the shaped precursor can be spherical, granular, strip-shaped, cylindrical, tooth ball-shaped or clover-shaped.

[0050] According to the present application, the modified oxide is selected from one or more of alkaline earth metal oxides, transition metal oxides, rare earth metal oxides and non-metal oxides; preferably, the modified oxide is selected from one or more of magnesium oxide, calcium oxide, strontium oxide, barium oxide, zinc oxide, cerium oxide, lanthanum oxide, zirconium dioxide, phosphorus-containing oxide and boron oxide. In the present application, the specific modified oxide selected from the present application has the advantage of improving the surface electron distribution of the molecular sieve and selectively covering part of the excessively strong acid centers, so that the surface properties of the catalyst are more suitable for the performance of the waste plastic cracking reaction.

[0051] According to the present application, the specific surface area of the waste plastic low-carbon olefin catalyst is 400-800 m 2 / g, and the pore volume is 0.5-1.1 cm 3 / g; preferably, the specific surface area of the catalyst is 532-675 m 2 / g, and the pore volume is 0.7-0.9 cm 3 / g. In the present application, the specific surface area and pore volume of the mesoporous material are large, but the specific surface area and pore volume of the shaped product mixed with the zeolite molecular sieve and the binder are both reduced.

[0052] The second aspect of the present application provides a preparation method of a waste plastic low-carbon olefin catalyst, wherein the preparation method comprises:

[0053] (1) mixing the shaped precursor with an aqueous solution of metal salt and performing a first contact reaction, and then removing water and performing a first drying treatment to obtain a catalyst intermediate; the shaped precursor comprises MCM-22 zeolite molecular sieve, SBA-15 full-silicon mesoporous molecular sieve and aluminum oxide;

[0054] (2) mixing the catalyst intermediate with an acidic aqueous solution and performing a second contact reaction, and then removing water, performing a second drying and calcination treatment to obtain a waste plastic low-carbon olefin catalyst.

[0055] According to the present application, in step (1), the metal salt is selected from inorganic salts containing alkaline earth metals, transition metals and rare earth metals; preferably, the modified oxide precursor is selected from inorganic salts containing magnesium, calcium, strontium, barium, zinc, cerium, lanthanum and zirconium;

[0056] According to the present application, in step (1), the concentration of the aqueous solution of the metal salt is 1-20%, preferably 2-10%;

[0057] According to the present application, in step (1), the first contact reaction conditions include: temperature is 20-90℃, time is 0.5-20h.

[0058] According to the present application, in step (1), the weight ratio of the molding precursor to the aqueous solution of the metal salt is 1:(2-30), preferably 1:(5-20).

[0059] According to the present application, in step (1), the first drying conditions include: temperature is 60-120℃; time is 3-12h.

[0060] According to the present application, in step (2), the acidic aqueous solution is selected from one or more of phosphoric acid or boric acid;

[0061] According to the present application, in step (2), the acidic aqueous solution concentration is 0.5-10%, preferably 1-5%;

[0062] According to the present application, in step (2), the weight ratio of the catalyst intermediate to the acidic aqueous solution is 1:(1-20), preferably 1:(3-15).

[0063] According to the present application, in step (2), the second contact reaction conditions include: temperature is 20-90℃, time is 0.5-10h.

[0064] According to the present application, in step (2), the second drying conditions include: temperature is 80-150℃; time is 3-30h.

[0065] According to the present application, in step (2), the calcination conditions include: temperature can be 450-650℃, preferably 500-600℃; time can be 2-20h, preferably 3-10h.

[0066] The third aspect of the present application provides a waste plastic low-carbon olefin catalyst prepared by the preparation method described above.

[0067] The fourth aspect of the present application provides an application of a waste plastic low-carbon olefin catalyst in a reaction of directly converting waste plastics into low-carbon olefins.

[0068] According to the present application, the application method of the catalyst includes: waste plastic powder is contacted with the waste plastic low-carbon olefin catalyst to perform a reaction.

[0069] In the present application, the conditions for contacting the waste plastic powder with the waste plastic low-carbon olefin catalyst include that the temperature for contacting can be 420-580℃, preferably 450-540℃; the pressure for contacting can be 0.01-1.0Mpa, preferably 0.05-0.5Mpa; the time for contacting can be 0.5-12h, preferably 1-5h; and the weight ratio of the waste plastic low-carbon olefin catalyst to the waste plastic powder can be 1:0.5-50, preferably 1:2-30.

[0070] The present application will be described in detail below through examples.

[0071] In the following examples and comparative examples:

[0072] The small-angle XRD test of the sample was performed on a high-power rotating target X-ray diffractometer of D8 ADVANCE type of BRUKER AXS company in Germany, and the scanning range was 0.5-10°.

[0073] The wide-angle XRD test of the sample was performed on an X-ray powder diffractometer of X'Pert MPD type of Philips company in the Netherlands, Cu Kα target, and the scanning range 2θ=5-90°.

[0074] The pore structure parameter analysis of the sample was performed on an adsorptometer of ASAP2020-M+C type 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.

[0075] 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.

[0076] The drying oven was produced by Shanghai Yiheng Scientific Instrument Co., Ltd., and the model was DHG-9030A.

[0077] The muffle furnace was produced by CARBOLITE company, and the model was CWF1100.

[0078] The MCM-22 zeolite molecular sieve with the model of NKF-10 used in the examples and comparative examples was purchased from Nankai University Catalyst Factory; the boehmite powder with the model of SB was purchased from Beijing Yatopuohua Chemical Auxiliary Co., Ltd.; the pseudo-boehmite powder with the model of P-DF-09-LSi was purchased from Shandong Aluminum Industry Co., Ltd.; the macroporous pseudo-boehmite powder with the model of PB-0101 was purchased from Zibo Hengqi Powder New Material Co., Ltd.; P123 (EO 20 PO 70 EO 20) were purchased from Sigma-Aldrich Chemistry Co. Ltd. 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.

[0079] Example 1

[0080] (1) Preparation of SBA-15 full-silicon mesoporous molecular sieve

[0081] 24.0 g of non-ionic surfactant P123 was added to 600 g of 2M hydrochloric acid aqueous solution, and stirred at 35℃ for 1 hour; 51.2 g of tetraethyl orthosilicate was added to the above solution, and stirred at 35℃ for 24 hours; the above mixture was transferred to an autoclave, and hydrothermally crystallized at 100℃ for 24 hours. After the hydrothermal reaction was completed, the solid product was separated from the mother liquor, washed with deionized water until neutral, dried at 110℃ for 6 hours and calcined at 550℃ for 6 hours to obtain full-silicon SBA-15 mesoporous molecular sieve A.

[0082] The specific surface area of the full-silicon SBA-15 mesoporous molecular sieve A was 967 m 2 / g; the average pore size was 7.0 nm, and the pore volume was 1.4 cm 3 / g.

[0083] (2) Preparation of the shaped precursor

[0084] 86 g of the full-silicon SBA-15 mesoporous molecular sieve A prepared in the above step was uniformly mixed with 88 g of MCM-22 molecular sieve (SiO2 / Al2O3 molar ratio of 30), 37 g of pseudo-boehmite powder with model number P-DF-09-L Si and 7 g of cellulose, 110 g of 5% nitric acid was added, stirred uniformly, extruded and cut into cylindrical shape with a diameter of 2 mm and a length of 2 mm; dried at 100℃ for 10 hours, and finally calcined at 580℃ for 6 hours to obtain the shaped precursor A.

[0085] Based on the total weight of the shaped precursor A, the content of the MCM-22 zeolite molecular sieve was 44% by weight, the content of the SBA-15 full-silicon mesoporous molecular sieve A was 43% by weight, and the content of the alumina was 13% by weight.

[0086] (3) Preparation of the waste plastic low-carbon olefin catalyst

[0087] A transparent aqueous solution was prepared by dissolving 6.6 g of calcium nitrate and 5.0 g of cerium nitrate in 1000 g of distilled water. 94 g of the shaped precursor A was mixed with the above aqueous solution and stirred at 50°C for 6 hours. The solvent water was removed by using a rotary evaporator and the product was dried at 80°C for 6 hours to obtain catalyst intermediate A. 3 g of boric acid was dissolved in 500 g of distilled water to obtain an aqueous boric acid solution. The catalyst intermediate A was mixed with the aqueous boric acid solution and stirred at 40°C for 4 hours. After removing the water by using a rotary evaporator, the solid product was dried at 120°C for 15 hours and calcined at 550°C for 6 hours to obtain catalyst A.

[0088] The content of the shaped precursor was 94 wt%, the content of calcium oxide was 2.2 wt%, the content of cerium oxide was 2.0 wt%, and the content of boron oxide was 1.8 wt% based on the total weight of catalyst A.

[0089] Figure 1 is the wide-angle XRD pattern of catalyst A; from Figure 1 It can be seen from the pattern of Figure 1 that the x-ray diffraction angles of the sample are mainly: 2θ = 7.0°, 7.1°, 8.2°, 10.0°, 14.2°, 26.1° and 28.1°. These seven diffraction signals are consistent with the diffraction pattern of MCM-22 zeolite molecular sieve, indicating that the MCM-22 zeolite molecular sieve in catalyst A still maintains a regular crystal phase structure, and the catalyst preparation process does not destroy the basic structure of the MCM-22 zeolite molecular sieve. In addition, the wide-angle XRD pattern of catalyst A shows four clear diffraction signals at 2θ = 37.1°, 45.3°, 61.0° and 66.6°. These four signals are consistent with the diffraction pattern of γ-Al2O3, indicating that the pseudo-boehmite with model number P-DF-09-LSi in catalyst A presents a typical γ-Al2O3 crystal phase after dehydration. There are no diffraction signals corresponding to the modified oxides in the wide-angle XRD pattern, indicating that the modified oxides are in a uniformly dispersed state on the catalyst.

[0090] Figure 2 is the small-angle XRD pattern of catalyst A; from Figure 2 It can be seen from the pattern of Figure 2 that the sample shows a sharp strong diffraction peak and two weak but clear diffraction peaks between 2θ = 0.5° and 2.0°. The above diffraction signals are characteristic diffraction peaks of SBA-15 mesoporous molecular sieve. It indicates that the SBA-15 mesoporous molecular sieve still has a relatively regular two-dimensional hexagonal 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.

[0091] The specific surface area of catalyst A is 675 m 2 / g, and the pore volume is 0.9 cm 3 / g.

[0092] (4) Performance evaluation of direct conversion of waste plastics to light olefins

[0093] The performance of the catalyst in the catalytic cracking of waste plastics was evaluated on a fixed bed reactor. The catalyst A was loaded at 10.0 g, and the polyethylene waste plastics were loaded at 50.0 g. The reaction temperature was 500°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). The quantitative analysis was performed by programmed temperature and correction factor. The liquid composition was analyzed by Agilent 6890 gas chromatograph equipped with a PONA column. The reaction results are shown in Table 1.

[0094] Example 2

[0095] (1) Preparation of SBA-15 all-silicon mesoporous molecular sieve

[0096] 30.0 g of non-ionic surfactant P123 was added to 450 g of 1M hydrochloric acid aqueous solution and stirred at 40°C for 1 hour. 45.0 g of tetramethyl orthosilicate was added dropwise to the above solution and stirred at 40°C for 24 hours. The mixture was transferred to an autoclave and hydrothermally crystallized at 120°C for 10 hours. After the hydrothermal reaction was completed, the solid product was separated from the mother liquor, washed with deionized water until neutral, dried at 120°C for 3 hours and calcined at 450°C for 12 hours to obtain SBA-15 all-silicon mesoporous molecular sieve B.

[0097] The specific surface area of SBA-15 all-silicon mesoporous molecular sieve B was 920 m 2 / g; the average pore size was 6.7 nm, and the pore volume was 1.3 cm 3 / g.

[0098] (2) Preparation of shaped precursor

[0099] 80 g of SBA-15 all-silicon mesoporous molecular sieve B prepared in the above step was uniformly mixed with 96 g of MCM-22 molecular sieve (SiO2 / Al2O3 molar ratio of 30), 34 g of pseudo-boehmite powder with model number PB-0101, and 10 g of sesbania powder. Then, 110 g of 3% nitric acid was added, and the mixture was stirred uniformly, extruded, and cut into cylindrical shapes with a diameter of 2 mm and a length of 2 mm. After drying at 120°C for 8 hours, the shaped precursor B was finally calcined at 600°C for 5 hours.

[0100] Based on the total weight of the shaped precursor B, the content of MCM-22 zeolite molecular sieve was 48% by weight, the content of SBA-15 all-silicon mesoporous molecular sieve B was 40% by weight, and the content of alumina was 12% by weight.

[0101] (3) Preparation of catalyst for producing low-carbon olefins from waste plastics

[0102] A transparent aqueous solution was prepared by dissolving 6.0 g of magnesium nitrate and 3.8 g of zinc nitrate in 800 g of distilled water. 96 g of the molding precursor B was mixed with the above aqueous solution and stirred at 70°C for 3 hours. The solvent water was removed using a rotary evaporator, and then the mixture was dried at 120°C for 2 hours to obtain a catalyst intermediate B. An aqueous solution of phosphoric acid was prepared by dissolving 1.6 g of phosphoric acid in 400 g of distilled water. The catalyst intermediate B was mixed with the aqueous solution of phosphoric acid and stirred at 30°C for 5 hours. After removing the water using a rotary evaporator, the solid product was dried at 150°C for 3 hours and then calcined at 600°C for 4 hours to obtain a catalyst B.

[0103] The content of the molding precursor was 96 wt%, the content of magnesium oxide was 1.8 wt%, the content of zinc oxide was 1.2 wt%, and the content of phosphorus-containing oxide was 1.0 wt% based on the total weight of the catalyst B.

[0104] The specific surface area of the catalyst B was 618 m 2 / g, and the pore volume was 0.8 cm 3 / g.

[0105] The reaction performance of the catalyst B was tested according to the method for evaluating the reaction performance of waste plastics for direct conversion to low-carbon olefins in step (4) of Example 1, and the evaluation results are shown in Table 1.

[0106] Example 3

[0107] (1) Preparation of SBA-15 all-silicon mesoporous molecular sieve

[0108] A non-ionic surfactant P123 was added to 800 g of 1.5 M aqueous hydrochloric acid solution and stirred at 40°C for 1 hour. 40.0 g of water glass (SiO2 content: 28.26 wt%) was added to the above solution and stirred at 40°C for 24 hours. The mixture was transferred to an autoclave and hydrothermally crystallized at 80°C for 40 hours. After the hydrothermal reaction, the solid product was separated from the mother liquor, washed with deionized water until neutral, dried at 70°C for 10 hours, and calcined at 650°C for 3 hours to obtain an SBA-15 all-silicon mesoporous molecular sieve C.

[0109] The specific surface area of the SBA-15 all-silicon mesoporous molecular sieve C was 892 m 2 / g, the average pore diameter was 6.4 nm, and the pore volume was 1.2 cm 3 / g.

[0110] (2) Preparation of molding precursor

[0111] SBA-15 full-silica mesoporous molecular sieve C 90 g prepared in the above step was mixed with 82 g of MCM-22 zeolite (molar ratio of SiO2 / Al2O3 was 30), 38 g of pseudo-boehmite powder of SB type, and 5 g of cellulose, and then 106 g of 8% dilute nitric acid was added. After stirring, the mixture was extruded and cut into cylinders with a diameter of 2 mm and a length of 2 mm. After drying at 80°C for 20 hours, the final calcination was performed at 500°C for 16 hours to obtain a shaped precursor C.

[0112] The content of MCM-22 zeolite was 41% by weight, the content of SBA-15 full-silica mesoporous molecular sieve C was 45% by weight, and the content of alumina was 14% by weight, based on the total weight of the shaped precursor C.

[0113] (3) Preparation of a waste plastic-to-olefin catalyst

[0114] Strontium nitrate 5.0 g, lanthanum nitrate 4.6 g, and zinc nitrate 3.4 g were dissolved in 1200 g of distilled water to obtain a transparent aqueous solution. 93 g of the shaped precursor C was mixed with the above aqueous solution and stirred at 40°C for 10 hours. The solvent water was removed using a rotary evaporator, and then the mixture was dried at 70°C for 10 hours to obtain a catalyst intermediate C. Boric acid 2.7 g was dissolved in 600 g of distilled water to obtain an aqueous boric acid solution. The above catalyst intermediate C was mixed with the aqueous boric acid solution and stirred at 60°C for 3 hours. After removing the water using a rotary evaporator, the solid product was dried at 80°C for 30 hours and then calcined at 500°C for 4 hours to obtain a catalyst C.

[0115] The content of the shaped precursor was 93% by weight, the content of strontium oxide was 2.5% by weight, the content of lanthanum oxide was 1.7% by weight, the content of zinc oxide was 1.2% by weight, and the content of boric oxide was 1.6% by weight, based on the total weight of the catalyst C.

[0116] The specific surface area of the catalyst C was 532 m 2 / g, and the pore volume was 0.7 cm 3 / g.

[0117] The reaction performance of the catalyst C was tested according to the waste plastic direct conversion to olefin reaction performance evaluation method of step (4) in Example 1, and the evaluation results are shown in Table 1.

[0118] Example 4

[0119] SBA-15 full-silica mesoporous molecular sieve A was prepared according to the method of step (1) in Example 1.

[0120] The shaped precursor D was prepared according to the method of step (2) in Example 1, except that the preparation conditions were changed as follows:

[0121] The SBA-15 mesoporous molecular sieve A prepared in the above step was mixed with 74 g of MCM-22 molecular sieve (SiO2 / Al2O3 molar ratio of 30), 26 g of pseudo-boehmite powder of type P-DF-09-LSi, and 8 g of cellulose, and then 102 g of 5% nitric acid was added. After stirring, the mixture was extruded and cut into cylinders with a diameter of 2 mm and a length of 2 mm. The cylinders were dried at 100°C for 10 hours and then calcined at 580°C for 6 hours to obtain the shaped precursor D.

[0122] The content of the MCM-22 zeolite was 37% by weight, the content of the SBA-15 mesoporous molecular sieve A was 53% by weight, and the content of the alumina was 10% by weight, based on the total weight of the shaped precursor D.

[0123] The waste plastic to light olefins catalyst D was prepared according to the method of step (3) in Example 1, except that the preparation conditions were changed as follows:

[0124] A transparent aqueous solution was prepared by dissolving 3.3 g of calcium nitrate and 2.5 g of cerium nitrate in 1000 g of distilled water. 97 g of the shaped precursor D was mixed with the aqueous solution and stirred at 50°C for 6 hours. The solvent water was removed using a rotary evaporator, and then the mixture was dried at 80°C for 6 hours to obtain the catalyst intermediate D. A boric acid aqueous solution was prepared by dissolving 1.5 g of boric acid in 500 g of distilled water. The catalyst intermediate D was mixed with the boric acid aqueous solution and stirred at 40°C for 4 hours. After removing the water using a rotary evaporator, the solid product was dried at 120°C for 15 hours and then calcined at 550°C for 6 hours to obtain the catalyst D.

[0125] The content of the shaped precursor was 97% by weight, the content of the calcium oxide was 1.1% by weight, the content of the cerium oxide was 1.0% by weight, and the content of the boron oxide was 0.9% by weight, based on the total weight of the catalyst D.

[0126] The specific surface area of the catalyst D was 704 m 2 / g, and the pore volume was 1.0 cm 3 / g.

[0127] The reaction performance of the catalyst D was tested according to the method for evaluating the reaction performance of the waste plastic to light olefins catalyst in step (4) in Example 1, and the evaluation results are shown in Table 1.

[0128] Example 5

[0129] The SBA-15 mesoporous molecular sieve B was prepared according to the method of step (1) in Example 2.

[0130] The shaped precursor E was prepared according to the method of step (2) in Example 2, except that the preparation conditions were changed as follows:

[0131] The SBA-15 all-silica mesoporous molecular sieve B prepared in the above step was mixed with 102 g of MCM-22 molecular sieve (molar ratio of Si02 / Al203was 30), 43 g of PB-0101 type pseudo-boehmite powder, and 10 g of sesbania powder, and then 106 g of 3% nitric acid was added and stirred uniformly, followed by extrusion and cutting into a cylindrical shape with a diameter of 2 mm and a length of 2 mm. After drying at 120°C for 8 hours, final calcination was performed at 600°C for 5 hours to obtain the shaped precursor E.

[0132] The content of the MCM-22 zeolite was 51% by weight, the content of the SBA-15 all-silica mesoporous molecular sieve B was 34% by weight, and the content of the alumina was 15% by weight, based on the total weight of the shaped precursor E.

[0133] The waste plastic-to-light olefins catalyst E was prepared according to the method of step (3) in Example 2, except that the preparation conditions were changed as follows:

[0134] The waste plastic-to-light olefins catalyst E was prepared according to the method of step (3) in Example 2, except that the preparation conditions were changed as follows:

[0135] The content of the MCM-22 zeolite was 51% by weight, the content of the SBA-15 all-silica mesoporous molecular sieve B was 34% by weight, and the content of the alumina was 15% by weight, based on the total weight of the shaped precursor E.

[0136] The specific surface area of the catalyst E was 490 m 2 / g, and the pore volume was 0.6 cm 3 / g.

[0137] The reaction performance of the catalyst E was tested according to the method for evaluating the reaction performance of the waste plastic-to-light olefins reaction of step (4) in Example 1, and the evaluation results are shown in Table 1.

[0138] Example 6

[0139] The SBA-15 all-silica mesoporous molecular sieve A was prepared according to the method of step (1) in Example 1.

[0140] The shaped precursor F was prepared according to the method of step (2) in Example 1, except that the preparation conditions were changed as follows:

[0141] The SBA-15 mesoporous molecular sieve A prepared in the above step was mixed with 68 g of MCM-22 molecular sieve (SiO2 / Al2O3molar ratio of 30), 11 g of pseudo-boehmite powder of type P-DF-09-L Si, and 8 g of cellulose, and then 102 g of 5% nitric acid was added. After stirring, the mixture was extruded and cut into cylinders with a diameter of 2 mm and a length of 2 mm. After drying at 100°C for 10 hours, the product was calcined at 580°C for 6 hours to obtain the shaped precursor F.

[0142] The content of the MCM-22 zeolite was 34% by weight, the content of the SBA-15 mesoporous molecular sieve A was 58% by weight, and the content of the alumina was 8% by weight, based on the total weight of the shaped precursor F.

[0143] The waste plastic to light olefins catalyst F was prepared according to the method of step (3) in Example 1, except that the preparation conditions were changed as follows:

[0144] Calcium nitrate 2.4 g and cerium nitrate 1.5 g were dissolved in 1000 g of distilled water to obtain a transparent aqueous solution. 98 g of the shaped precursor F was mixed with the above aqueous solution and stirred at 50°C for 6 hours. The solvent water was removed using a rotary evaporator, and then the product was dried at 80°C for 6 hours to obtain the catalyst intermediate F. Boric acid 1.0 g was dissolved in 500 g of distilled water to obtain an aqueous boric acid solution. The above catalyst intermediate F was mixed with the aqueous boric acid solution and stirred at 40°C for 4 hours. After removing the water using a rotary evaporator, the solid product was dried at 120°C for 15 hours and then calcined at 550°C for 6 hours to obtain the catalyst F.

[0145] The content of the shaped precursor was 98% by weight, the content of calcium oxide was 0.8% by weight, the content of cerium oxide was 0.6% by weight, and the content of boron oxide was 0.6% by weight, based on the total weight of the catalyst F.

[0146] The specific surface area of the catalyst F was 769 m 2 / g, and the pore volume was 1.1 cm 3 / g.

[0147] The reaction performance of the catalyst F was tested according to the method for evaluating the reaction performance of the waste plastic to light olefins catalyst in step (4) in Example 1, and the evaluation results are shown in Table 1.

[0148] Example 7

[0149] SBA-15 full-silica mesoporous molecular sieve B was prepared according to the method of step (1) in Example 2.

[0150] Molded precursor G was prepared according to the method of step (2) in Example 2, except that the preparation conditions were changed as follows.

[0151] The SBA-15 full-silica mesoporous molecular sieve B 54 g prepared in the above step was mixed with 110 g of MCM-22 zeolite (SiO2 / Al2O3 molar ratio of 30), 51 g of pseudo-boehmite powder of PB-0101 type, and 10 g of sesbania powder, and then 110 g of 3% nitric acid was added. After stirring, the mixture was extruded and cut into a cylindrical shape having a diameter of 2 mm and a length of 2 mm. After drying at 120°C for 8 hours, the product was calcined at 600°C for 5 hours to obtain the molded precursor G.

[0152] The content of the MCM-22 zeolite was 55% by weight, the content of the SBA-15 full-silica mesoporous molecular sieve B was 27% by weight, and the content of the alumina was 18% by weight, based on the total weight of the molded precursor G.

[0153] Waste plastic-to-light olefins catalyst E was prepared according to the method of step (3) in Example 2, except that the preparation conditions were changed as follows.

[0154] Magnesium nitrate 15.0 g and zinc nitrate 9.5 g were dissolved in 800 g of distilled water to obtain a transparent aqueous solution. 90 g of the molded precursor G was mixed with the above aqueous solution and stirred at 70°C for 3 hours. The solvent water was removed using a rotary evaporator, and then the product was dried at 120°C for 2 hours to obtain a catalyst intermediate G. Phosphoric acid 4.0 g was dissolved in 400 g of distilled water to obtain an aqueous phosphoric acid solution. The above catalyst intermediate G was mixed with the aqueous phosphoric acid solution and stirred at 30°C for 5 hours. After removing the water using a rotary evaporator, the solid product was dried at 150°C for 3 hours and then calcined at 600°C for 4 hours to obtain the catalyst G.

[0155] The content of the molded precursor was 90% by weight, the content of magnesium oxide was 4.5% by weight, the content of zinc oxide was 3.0% by weight, and the content of phosphorus-containing oxide was 2.5% by weight, based on the total weight of the catalyst G.

[0156] The specific surface area of the catalyst G was 437 m 2 / g, and the pore volume was 0.5 cm 3 / g.

[0157] The reaction performance of the catalyst E was tested according to the waste plastic direct conversion to light olefins reaction performance evaluation method of step (4) in Example 1, and the evaluation results are shown in Table 1.

[0158] Comparative Example 1

[0159] SBA-15 full-silica mesoporous molecular sieve A was prepared according to the method of step (1) in Example 1.

[0160] D1 of the shaped precursor was prepared according to the method of step (2) in Example 1, except that the preparation conditions were changed as follows.

[0161] 140 g of the full-silica SBA-15 mesoporous molecular sieve A prepared in the above step, 48 g of MCM-22 molecular sieve (SiO2 / Al2O3 molar ratio of 30), 9 g of pseudo-boehmite powder of type P-DF-09-LSi, and 7 g of cellulose were uniformly mixed, 120 g of 5% nitric acid was added, and after uniform stirring, extrusion and cutting were performed to form a cylinder shape having a diameter of 2 mm and a length of 2 mm; drying was performed at 100°C for 10 hours, and finally calcination was performed at 580°C for 6 hours to obtain the shaped precursor D1.

[0162] The content of the MCM-22 zeolite molecular sieve was 24% by weight, the content of the SBA-15 full-silica mesoporous molecular sieve A was 70% by weight, and the content of the alumina was 6% by weight, based on the total weight of the shaped precursor D1.

[0163] The waste plastic low-carbon olefin catalyst D1 was prepared according to the method of step (3) in Example 1, except that the preparation conditions were changed as follows.

[0164] 1.2 g of calcium nitrate and 0.7 g of cerium nitrate were dissolved in 1000 g of distilled water to obtain a transparent aqueous solution. 99 g of the shaped precursor D1 was mixed with the above aqueous solution and stirred at 50°C for 6 hours; a rotary evaporator was used to remove the solvent water, and then drying was performed at 80°C for 6 hours to obtain a catalyst intermediate D1. 0.5 g of boric acid was dissolved in 500 g of distilled water to obtain an aqueous boric acid solution. The above catalyst intermediate D1 was mixed with the aqueous boric acid solution and stirred at 40°C for 4 hours, and then the water was removed using a rotary evaporator; the solid product was dried at 120°C for 15 hours and calcined at 550°C for 6 hours to obtain the catalyst D1.

[0165] The content of the shaped precursor was 99% by weight, the content of calcium oxide was 0.4% by weight, the content of cerium oxide was 0.3% by weight, and the content of boron oxide was 0.3% by weight, based on the total weight of the catalyst D1.

[0166] The specific surface area of the catalyst D1 was 811 m 2 / g, and the pore volume was 1.1 cm 3 / g.

[0167] The reaction performance of catalyst D1 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.

[0168] Comparative Example 2

[0169] SBA-15 full-silica mesoporous molecular sieve B was prepared according to the method in step (1) in Example 2.

[0170] The shaped precursor D2 was prepared according to the method in step (2) in Example 2, except that the preparation conditions were changed, and the specific process was as follows:

[0171] The SBA-15 full-silica mesoporous molecular sieve B prepared in the above step was mixed with 136 g of MCM-22 molecular sieve (molar ratio of SiO2 / Al2O3 was 30), 28 g of pseudo-boehmite powder with model number PB-0101, and 12 g of sesbania powder, and then 115 g of 3% nitric acid was added. After stirring, it was extruded and cut into a cylindrical shape with a diameter of 2 mm and a length of 2 mm. After drying at 120°C for 8 hours, it was finally calcined at 600°C for 5 hours to obtain the shaped precursor D2.

[0172] The content of the MCM-22 zeolite molecular sieve was 68% by weight, the content of the SBA-15 full-silica mesoporous molecular sieve B was 12% by weight, and the content of the aluminum oxide was 20% by weight, based on the total weight of the shaped precursor D2.

[0173] The waste plastic light olefin catalyst D2 was prepared according to the method in step (3) in Example 2, except that the preparation conditions were changed, and the specific process was as follows:

[0174] 24.0 grams of magnesium nitrate and 15.2 grams of zinc nitrate were dissolved in 800 g of distilled water to obtain a transparent aqueous solution. 84 g of the shaped precursor D2 was mixed with the above aqueous solution and stirred at 70°C for 3 hours. The solvent water was removed using a rotary evaporator, and then dried at 120°C for 2 hours to obtain a catalyst intermediate D2. 6.4 grams of phosphoric acid was dissolved in 400 g of distilled water to obtain a phosphoric acid aqueous solution. The above catalyst intermediate D2 was mixed with the phosphoric acid aqueous solution and stirred at 30°C for 5 hours. After removing the water using a rotary evaporator, the solid product was dried at 150°C for 3 hours and calcined at 600°C for 4 hours to obtain the catalyst D2.

[0175] The content of the shaped precursor was 84% by weight, the content of the magnesium oxide was 7.2% by weight, the content of the zinc oxide was 4.8% by weight, and the content of the phosphorus-containing oxide was 4.0% by weight, based on the total weight of the catalyst D2.

[0176] The specific surface area of the catalyst D2 was 384 m 2 / g, and the pore volume was 0.4 cm3 / g.

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

[0178] Comparative Example 3

[0179] SBA-15 full-silicon mesoporous molecular sieve A was prepared according to the method in step (1) in Embodiment 1.

[0180] The shaped precursor D3 was prepared according to the method in step (2) in Embodiment 1, except that the preparation conditions were changed, and no MCM-22 zeolite molecular sieve was used, and the specific process was as follows:

[0181] The full-silicon SBA-15 mesoporous molecular sieve A 174 g prepared in the above step was mixed uniformly with 37 g pseudo-boehmite powder with a model number of P-DF-09-LSi and 7 g cellulose, 110 g 5% nitric acid was added, and after stirring uniformly, it was extruded and cut into a cylindrical shape with a diameter of 2 mm and a length of 2 mm; dried at 100°C for 10 hours, and finally calcined at 580°C for 6 hours to obtain the shaped precursor D3.

[0182] The content of the SBA-15 full-silicon mesoporous molecular sieve A was 87% by weight, and the content of the aluminum oxide was 13% by weight, based on the total weight of the shaped precursor D3.

[0183] The waste plastic light olefin catalyst D3 was prepared according to the method in step (3) in Embodiment 1. The content of the shaped precursor D3 was 94% by weight, the content of the calcium oxide was 2.2% by weight, the content of the cerium oxide was 2.0% by weight, and the content of the boron oxide was 1.8% by weight, based on the total weight of the catalyst D3.

[0184] The specific surface area of the catalyst D3 was 857 m 2 / g, and the pore volume was 1.2 cm 3 / g.

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

[0186] Comparative Example 4

[0187] The catalyst D4 was prepared according to the same method as in Embodiment 2, except that step (1) in Embodiment 2 was cancelled; the shaped precursor D4 was prepared according to the method in step (2) in Embodiment 2, except that the preparation conditions were changed, and no full-silicon SBA-15 mesoporous molecular sieve was used, and the specific process was as follows:

[0188] 176 g of MCM-22 molecular sieve (molar ratio of SiO2 / Al2O3 of 30), 34 g of pseudo-boehmite powder of PB-0101 type and 10 g of sesbania powder were mixed uniformly, 110 g of 3% nitric acid was added, and after stirring uniformly, extrusion and cutting into a cylindrical shape with a diameter of 2 mm and a length of 2 mm were performed; drying at 120°C for 8 hours, and finally calcination at 600°C for 5 hours were performed, to obtain a shaped precursor D4.

[0189] The content of the MCM-22 zeolite molecular sieve was 88% by weight and the content of the alumina was 12% by weight, based on the total weight of the shaped precursor D4.

[0190] The waste plastic-to-light olefins catalyst D4 was prepared according to the method of step (3) in Example 2. The content of the shaped precursor D4 was 96% by weight, the content of the magnesium oxide was 1.8% by weight, the content of the zinc oxide was 1.2% by weight, and the content of the phosphorus-containing oxide was 1.0% by weight, based on the total weight of the catalyst D4.

[0191] The specific surface area of the catalyst D4 was 326 m 2 / g, and the pore volume was 0.4 cm 3 / g.

[0192] The reaction performance of the catalyst D4 was tested according to the waste plastic direct conversion to light olefins reaction performance evaluation method of step (4) in Example 1, and the evaluation results are listed in Table 1.

[0193] Comparative Example 5

[0194] The SBA-15 all-silicon mesoporous molecular sieve A was prepared according to the method of step (1) in Example 1.

[0195] The shaped precursor A was prepared according to the method of step (2) in Example 1.

[0196] The waste plastic-to-light olefins catalyst D5 was prepared according to the method of step (3) in Example 1, except that the preparation conditions were changed and the modified oxide was changed to sodium oxide, and the specific process was as follows:

[0197] 22.2 g of sodium nitrate was dissolved in 1000 g of distilled water to obtain a transparent aqueous solution. 94 g of the shaped precursor A was mixed with the above aqueous solution and stirred at 50°C for 6 hours; after removing the water using a rotary evaporator, the solid product was dried at 120°C for 15 hours and calcined at 550°C for 6 hours to obtain the catalyst D5. The content of the shaped precursor A was 94% by weight and the content of the sodium oxide was 6% by weight, based on the total weight of the catalyst D5.

[0198] The reaction performance of catalyst D5 was tested according to the reaction performance evaluation method of direct conversion of waste plastics to light olefins reaction in step (4) in embodiment 1, and the evaluation results are listed in Table 1.

[0199] Comparative example 6

[0200] SBA-15 full-silica mesoporous molecular sieve A was prepared according to the method in step (1) in embodiment 1.

[0201] The shaped precursor D6 was prepared according to the method in step (2) in embodiment 1, except that the pseudo-boehmite powder with model number P-DF-09-L Si was not used as the binder, and the silicon sol with trade name HS-30 (purchased from Zhejiang Yuda Chemical Co., Ltd.) was used as the binder. As a result, the content of the MCM-22 zeolite molecular sieve was 44% by weight, the content of the SBA-15 full-silica mesoporous molecular sieve A was 43% by weight, and the content of the silicon dioxide remaining after calcination of the binder was 13% by weight, based on the total weight of the shaped precursor D6.

[0202] The waste plastic light olefin catalyst D6 was prepared according to the method in step (3) in embodiment 1, and the content of the shaped precursor was 94% by weight, the content of the calcium oxide was 2.2% by weight, the content of the cerium oxide was 2.0% by weight, and the content of the boron oxide was 1.8% by weight, based on the total weight of the catalyst D6.

[0203] The reaction performance of catalyst D6 was tested according to the reaction performance evaluation method of direct conversion of waste plastics to light olefins reaction in step (4) in embodiment 1, and the evaluation results are listed in Table 1.

[0204] Comparative example 7

[0205] Catalyst D7 was prepared according to the same method as in embodiment 1, except that the “MCM-22 molecular sieve” in embodiment 1 was replaced by “full-silica silicalite-1 molecular sieve (purchased from Tianjin Nanhua Catalyst Co., Ltd., with a specific surface area of 318 m 2 / g, and a pore volume of 0.35 cm 3 / g)”, and the specific surface area of the catalyst was 521 m 2 / g, and the pore volume was 0.6 cm 3 / g.

[0206] The reaction performance of catalyst D7 was tested according to the reaction performance evaluation method of direct conversion of waste plastics to light olefins reaction in step (4) in embodiment 1, and the evaluation results are listed in Table 1.

[0207] Comparative example 8

[0208] Catalyst D8 was prepared in the same manner as Example 1, except that the "full-silica SBA-15 mesoporous molecular sieve" in Example 1 was replaced by "commercially available silica (purchased from Qingdao Hailang Silica Gel Dryer Factory, specific surface area 329 m 2 / g, pore volume 0.6 cm 3 / g) and the specific surface area of the catalyst was 204 m 2 / g, pore volume 0.4 cm 3 / g.

[0209] The reaction performance of catalyst D8 was tested according to the method for evaluating the reaction performance of direct conversion of waste plastics to low-carbon olefins in step (4) in Example 1, and the evaluation results are listed in Table 1.

[0210] Table 1

[0211]

[0212]

[0213] From the above results, it can be seen that the waste plastic low-carbon olefin catalyst provided by the present application can directly catalytically convert waste plastics to generate low-carbon olefins. The conversion rate of waste plastics is 100%, and the yield of low-carbon olefins is high.

[0214] In Comparative Example 1, the content of SBA-15 full-silica mesoporous molecular sieve is too high, the content of MCM-22 zeolite molecular sieve is too low, and the content of the modification component is not within the scope of the claims. Due to the small number of acid sites on the catalyst and the lack of active sites during the reaction, the conversion rate of the raw material is low and the yield of low-carbon olefins is low.

[0215] In Comparative Example 2, the content of SBA-15 full-silica mesoporous molecular sieve is too low, the content of MCM-22 zeolite molecular sieve is too high, and the content of the modification component is not within the scope of the claims. Due to the small number of mesoporous channels in the catalyst and the diffusion of reactant and product molecules during the reaction, the yield of low-carbon olefins is low.

[0216] In Comparative Example 3, the catalyst does not contain MCM-22 zeolite molecular sieve, but only contains SBA-15 full-silica mesoporous molecular sieve. Due to the lack of almost no acid sites on the catalyst and the severe lack of active sites during the reaction, the conversion rate of the raw material is very low and the yield of low-carbon olefins is low.

[0217] In Comparative Example 4, the catalyst does not contain SBA-15 full-silica mesoporous molecular sieve, but only contains MCM-22 zeolite molecular sieve. Due to the lack of mesoporous channels in the catalyst and the severe diffusion of reactant and product molecules during the reaction, the yield of low-carbon olefins is low.

[0218] In Comparative Example 5, instead of the modified oxide specifically defined in the present application, sodium oxide was used. Due to the lower modification effect of the same weight of sodium oxide, the low carbon olefin yield was low.

[0219] In Comparative Example 6, instead of the pseudo-boehmite powder with the type P-DF-09-LSi as the binder, a silica sol with the trade name HS-30 (purchased from Zhejiang Yuda Chemical Co., Ltd.) was used as the binder. The residual component after the binder was calcined was silicon dioxide. In the present application, when the silica sol was used as the binder, the binding effect was poor, the shape of the shaped precursor was irregular, the strength was poor, and the mixing of the components was not uniform enough. Therefore, the catalyst had a poor effect during the reaction, resulting in a low low carbon olefin yield.

[0220] In Comparative Example 7, the "MCM-22 molecular sieve" was replaced by "all-silica silicalite-1 molecular sieve". Although the all-silica silicalite-1 molecular sieve also belongs to microporous materials, the surface acidity is extremely weak and almost has no catalytic activity. Therefore, the prepared catalyst D7 almost does not contain acid sites on the surface, and the waste plastic catalytic cracking reaction process lacks active sites, resulting in only thermal cracking of the raw material, so the conversion rate is low and the low carbon olefin yield is low.

[0221] In Comparative Example 8, the "all-silica SBA-15 mesoporous molecular sieve A" was replaced by "commercially available silica". Although the pore of the commercially available silica also belongs to the mesoporous category, it belongs to an amorphous crystal phase structure, and the pore size is irregular. Compared with the all-silica SBA-15 mesoporous molecular sieve, the diffusion promoting effect is poor, resulting in a low low carbon olefin yield.

[0222] 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 disclosed in the present application and fall within the protection scope of the present application.

Claims

1. Application of a catalyst for producing light olefins from waste plastics in the direct conversion of waste plastics to light olefins, the application comprising: The method comprises contacting plastic powder with a waste plastics catalyst for light olefin production to carry out a reaction, wherein the plastic powder is polyethylene waste plastic, the waste plastics catalyst for light olefin production comprises a forming precursor and a modified oxide supported on the forming precursor, the forming precursor comprises MCM-22 zeolite molecular sieve, SBA-15 all-silicon mesoporous molecular sieve and alumina, and based on the total weight of the waste plastics catalyst for light olefin production, the content of the forming precursor is 90-98% by weight, and the content of the modified oxide is 2-10% by weight; Based on the total weight of the formed precursor, the content of the MCM-22 zeolite molecular sieve is 37-51% by weight, the content of the SBA-15 all-silica mesoporous molecular sieve is 34-53% by weight, and the content of the alumina is 10-15% by weight; The specific surface area of ​​the waste plastics light olefin catalyst is 532-675m 2 / g, pore volume of 0.7-0.9cm 3 / g.

2. The use according to claim 1, wherein Based on the total weight of the waste plastics-based light olefin catalyst, the content of the forming precursor is 92-97 weight %, and the content of the modified oxide is 3-8 weight %.

3. The use according to claim 2, wherein: Based on the total weight of the waste plastics-based light olefin catalyst, the content of the forming precursor is 93-96 weight %, and the content of the modified oxide is 4-7 weight %.

4. The use according to claim 1, wherein The average pore size of the SBA-15 all-silica mesoporous molecular sieve is 5-8 nm, and the specific surface area is 650-1100 m 2 / g, pore volume of 1.2-1.6cm 3 / g; And / or, the specific surface area of ​​the MCM-22 zeolite molecular sieve is 400-600m 2 / g, pore volume of 0.4-0.7cm 3 / g.

5. The use according to any one of claims 1 to 3, wherein: The modified oxide is selected from one or more of alkaline earth metal oxides, transition metal oxides and non-metal oxides.

6. The use according to claim 5, wherein: The modified oxide is selected from one or more of magnesium oxide, calcium oxide, strontium oxide, barium oxide, zinc oxide, cerium oxide, lanthanum oxide, zirconium dioxide, phosphorus-containing oxides and boron oxide.

7. The use according to claim 1, wherein: The preparation method of the molded precursor comprises: In the presence of an acidic aqueous solution, MCM-22 zeolite molecular sieve, all-silicon SBA-15 mesoporous molecular sieve, alumina precursor and an extrusion aid are mixed, extruded and then dried and calcined to obtain a formed precursor.

8. The use according to claim 7, wherein: The acidic aqueous solution is selected from one or more of dilute nitric 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 alumina precursor is selected from one or more of pseudo-boehmite, aluminum hydroxide gel, aluminum sol, gibbsite and boehmite; 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 MCM-22 molecular sieve, the all-silicon SBA-15 mesoporous molecular sieve, the alumina precursor, the extrusion aid, and the acidic aqueous solution is 1: (0.4-2): (0.2-0.6): (0.02-0.16): (0.8-1.6); And / or, the calcination conditions include: temperature of 450-650° C. and time of 2-30 h.

9. The use according to claim 8, wherein: The acidic aqueous solution is dilute nitric acid; and / or, the concentration of the acidic aqueous solution is 2-15%; and / or, the extrusion aid is cellulose or sesbania powder; And / or, the weight ratio of the MCM-22 molecular sieve, the all-silicon SBA-15 mesoporous molecular sieve, the alumina precursor, the extrusion aid and the acidic aqueous solution is 1: (0.6-1.5): (0.3-0.5): (0.04-0.12): (1.0-1.4).

10. The use according to any one of claims 1 to 3, wherein: The preparation method of the catalyst for preparing light olefins from waste plastics comprises: (1) mixing a shaped precursor with an aqueous solution of a metal salt and performing a first contact reaction, and then performing a first drying treatment to obtain a catalyst intermediate; the shaped precursor comprises MCM-22 zeolite molecular sieve, SBA-15 all-silica mesoporous molecular sieve and alumina; (2) The catalyst intermediate is mixed with an acidic aqueous solution and subjected to a second contact reaction, and then subjected to water removal, a second drying and calcination treatment to obtain a waste plastics-to-low-carbon olefin catalyst.

11. The use according to claim 10, wherein in step (1), the metal salt is selected from inorganic salts containing alkaline earth metals and transition metals; and / or, in step (1), the concentration of the aqueous solution of the metal salt is 1-20%; And / or, in step (1), the conditions of the first contact reaction include: The temperature is 20-90℃ and the time is 0.5-20h; And / or, in step (1), the weight ratio of the forming precursor to the aqueous solution of the metal salt is 1:(2-30).

12. The use according to claim 11, wherein in step (1), the metal salt is selected from inorganic salts containing magnesium, calcium, strontium, barium, zinc, cerium, lanthanum and zirconium; and / or, in step (1), the concentration of the aqueous solution of the metal salt is 2-10%; And / or, in step (1), the weight ratio of the forming precursor to the aqueous solution of the metal salt is 1:(5-20).

13. The use according to claim 10, wherein in step (2), the acidic aqueous solution is selected from one or more of phosphoric acid and boric acid; and / or, in step (2), the concentration of the acidic aqueous solution is 0.5-10%; and / or, in step (2), the weight ratio of the catalyst intermediate to the acidic aqueous solution is 1:(1-20); And / or, in step (2), the conditions of the second contact reaction include: The temperature is 20-90℃ and the time is 0.5-10h; And / or, in step (2), the calcination conditions include: temperature of 450-650°C; time of 2-20h.

14. The use according to claim 13, wherein in step (2), the concentration of the acidic aqueous solution is 1-5%; and / or, in step (2), the weight ratio of the catalyst intermediate to the acidic aqueous solution is 1:(3-15); And / or, in step (2), the roasting conditions include: The temperature is 500-600℃; the time is 3-10h.

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

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