Novel catalysts, their preparation methods, and their application in the direct conversion of waste plastics to low-carbon olefins.

Abstract

This invention relates to the fields of catalysts and polymer material recycling, and discloses a novel catalyst, its preparation method, and its application in the direct conversion of waste plastics to low-carbon olefins. The novel catalyst comprises ZSM-5 molecular sieve, SBA-16 all-silica mesoporous molecular sieve, a first modified oxide, and a second modified oxide. Based on the total weight of the novel catalyst, the content of ZSM-5 molecular sieve is 35-65% by weight, the content of SBA-16 all-silica mesoporous molecular sieve is 26-52.5% by weight, the content of the first modified oxide is 0.5-8% by weight, and the content of the second modified oxide is 1-12% by weight. This method solves the problem of waste plastic recycling and increases the production of important chemical raw materials such as low-carbon olefins.

Description

Technical Field

[0001] This invention relates to the fields of catalysts and polymer recycling, specifically to a novel catalyst, its preparation method, and its application in the direct conversion of waste plastics into low-carbon olefins. Background Technology

[0002] Since their invention in the 20th century, plastic products have been widely used in various fields worldwide due to their lightweight, high strength, corrosion resistance, good chemical stability, ease of processing, and aesthetic appeal. However, plastics are difficult to degrade naturally. While conventional landfill technology requires less investment and is simple to operate, it occupies large amounts of land and causes soil pollution. Incineration technology can achieve volume reduction requirements and recover some energy, but this process easily releases large amounts of hydrocarbons, nitrogen oxides, sulfides, and highly toxic substances, directly threatening human and environmental health. Therefore, the recycling and high-value utilization of waste plastics is a measure to save energy and protect the environment, and has received widespread attention from countries around the world. Methods for recycling and utilizing waste plastics mainly include sorting and recycling, producing monomer raw materials, producing clean fuels, and using them for power generation.

[0003] my country's plastics industry is one of the pillar industries of the national economy, and my country has now entered the ranks of the world's major plastic producers. Under the backdrop of new plastic restriction orders, a sharp decline in imports, and waste sorting policies, my country's waste plastic recycling companies are gradually moving away from the old path of extensive expansion and are beginning to examine their industrial layout from a green development perspective. They are continuously deepening cooperation with environmental protection and sanitation companies to gradually achieve the goals of green, low-carbon, and circular development. Large-scale waste plastic recycling companies with standardized operations will gradually further refine the classification of recycled waste plastics, continuously develop and apply new technologies and products for waste plastics, gradually broaden the application fields of waste plastics, and increase the added value of recycled plastic products. Among existing technologies, the main chemical recycling solution for waste plastics is waste plastic pyrolysis technology. Waste plastic pyrolysis includes three basic methods: thermal pyrolysis (one-stage method), catalytic pyrolysis (one-stage method), and thermal pyrolysis-catalytic modification (two-stage method). The earliest developed waste plastic pyrolysis technology was thermal pyrolysis. This technology refers to a thermal conversion process that involves a thermochemical decomposition reaction under high-temperature, oxygen-free conditions, transforming large-molecule organic matter in waste plastic products into small-molecule liquids, fuel gas, and coke. The reaction temperature in this process is generally controlled between 350-900℃. Adding a catalyst during the pyrolysis process creates catalytic pyrolysis, which not only lowers the pyrolysis temperature but also improves product performance. The pyrolysis-catalytic modification method, an improvement on catalytic pyrolysis, uses a catalyst to catalytically modify the pyrolysis gas after the waste plastic pyrolysis. This method produces higher-quality products, offers greater operational flexibility, and lower operating costs compared to both pyrolysis and catalytic pyrolysis, but the process is more complex.

[0004] Pyrolysis technology for treating waste plastics offers great flexibility and good energy recovery, making it one of the most promising technologies for waste plastic treatment. In existing technologies, one-step pyrolysis and one-step catalytic pyrolysis primarily produce fuel oil, yielding only small amounts of low-carbon olefins (ethylene, propylene, butene). If a large quantity of low-carbon olefins is required, a two-stage process of pyrolysis-catalytic reforming is necessary. Therefore, exploring a new chemical recycling process to produce pure and high-quality final products is an important research direction in plastic waste treatment. Summary of the Invention

[0005] The purpose of this invention is to address the current problem of low-carbon olefin content in the products of catalytic cracking reactions of waste plastics by providing a novel catalyst, its preparation method, and its application in the direct conversion of waste plastics to low-carbon olefins. This method not only solves the problem of waste plastic recycling but also increases the production of important chemical raw materials such as low-carbon olefins.

[0006] To achieve the above objectives, the first aspect of the present invention provides a novel catalyst, wherein the novel catalyst comprises ZSM-5 molecular sieve, SBA-16 all-silica mesoporous molecular sieve, a first modified oxide, and a second modified oxide, and based on the total weight of the novel catalyst, the content of ZSM-5 molecular sieve is 35-65% by weight, the content of SBA-16 all-silica mesoporous molecular sieve is 26-52.5% by weight, the content of the first modified oxide is 0.5-8% by weight, and the content of the second modified oxide is 1-12% by weight.

[0007] A second aspect of the present invention provides a method for preparing the aforementioned novel catalyst, wherein the preparation method comprises:

[0008] ZSM-5 molecular sieve and SBA-16 all-silica mesoporous molecular sieve were mixed with an aqueous solution of modified components and reacted in contact; then, after dehydration, drying and calcination, a novel catalyst was obtained.

[0009] The modified component aqueous solution comprises an acid, a metal salt, and water; the acid is phosphoric acid and / or boric acid; the metal salt is selected from one or more nitrates of magnesium, calcium, strontium, barium, zinc, copper, cobalt, cerium, lanthanum, and zirconium, preferably one or more of calcium nitrate, barium nitrate, and magnesium nitrate hexahydrate.

[0010] A third aspect of the present invention provides the application of the aforementioned novel catalyst in the direct conversion of waste plastics to low-carbon olefins.

[0011] Compared with the prior art, the technical solution of the present invention has the following advantages through the above technical solution:

[0012] (1) The novel catalyst provided by the present invention has readily available raw materials, a simple preparation method, easy-to-control conditions, and good product repeatability.

[0013] (2) The novel catalyst provided by the present invention includes acidic zeolite molecular sieves and large-pore mesoporous materials, which have stable structure, good high temperature resistance, and facilitate the diffusion of raw material and product molecules during the pyrolysis reaction.

[0014] (3) The novel catalyst provided by this invention can convert waste plastics into low-carbon olefins in one step when used in the direct conversion reaction of waste plastics into low-carbon olefins, which is a new method for the chemical recycling of waste plastics. It not only solves the problem of waste plastic recycling, but also increases the production of important chemical raw materials such as low-carbon olefins, and has good economic benefits.

[0015] (4) The novel catalyst provided by this invention has mild process conditions, is easy to operate and has low requirements for reaction equipment when used for the direct conversion of waste plastics to low carbon olefins.

[0016] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0017] Figure 1 This is the small-angle X-ray diffraction (XRD) pattern of the novel catalyst A in Example 1;

[0018] Figure 2 This is the wide-angle X-ray diffraction (XRD) spectrum of the novel catalyst A in Example 1. Detailed Implementation

[0019] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0020] As previously stated, the first aspect of this invention provides a novel catalyst, wherein the novel catalyst comprises ZSM-5 molecular sieve, SBA-16 all-silica mesoporous molecular sieve, a first modified oxide, and a second modified oxide, and based on the total weight of the novel catalyst, the content of ZSM-5 molecular sieve is 35-65% by weight, the content of SBA-16 all-silica mesoporous molecular sieve is 26-52.5% by weight, the content of the first modified oxide is 0.5-8% by weight, and the content of the second modified oxide is 1-12% by weight.

[0021] The inventors of this invention discovered that the main components of the pyrolysis catalysts disclosed in the prior art are microporous zeolite molecular sieves (including ZSM-5, ZSM-11, ZSM-35, or ZRP). Although microporous molecular sieves have an ordered and stable structure, their pore size is relatively narrow, generally between 0.4-0.7 nm. Waste plastic products have a large molecular weight and relatively long molecular chains. During the pyrolysis reaction of waste plastic products, the diffusion of larger reactant and product molecules is difficult in the narrow pores, which not only affects the contact between reactants and active centers but also easily leads to side reactions such as deep dehydrogenation. SBA-16 all-silica mesoporous molecular sieve has the structural advantages of large specific surface area and large pore volume, as well as the performance advantage of high temperature resistance. However, the silica surface, which is composed of silicon and oxygen as the basic framework structure, does not contain functional groups, resulting in poor activity in the pyrolysis reaction. The inventors of this invention discovered during their research and development of catalysts for the pyrolysis of waste plastics that by comprehensively utilizing the structural advantages of all-silica mesoporous inorganic materials and the surface acidic centers of zeolite molecular sieves, and by mixing and modifying a certain amount of SBA-16 all-silica mesoporous molecular sieve with ZSM-5 zeolite molecular sieve, which has a high silicon-to-aluminum molar ratio, as the main component of the catalyst for the pyrolysis reaction of waste plastics, not only can the activity of the pyrolysis catalyst be effectively improved, but also the selectivity of low-carbon olefins can be increased.

[0022] According to the present invention, the ZSM-5 molecular sieve framework structure is fixed, and its framework consists of two intersecting channel systems. The cylindrical channels are elliptical, with their major axis being... minor axis is Another type is a "Z"-shaped transverse channel with a nearly circular cross-section and a diameter of [missing information]. Compared to the narrow-pore ZSM-5 molecular sieve, the SBA-16 all-silica mesoporous molecular sieve has an average pore size between 5-8 nm and a specific surface area higher than 600 m². 2 / g. Mixing an appropriate amount of SBA-16 all-silica mesoporous molecular sieve with high silica-to-alumina ratio ZSM-5 facilitates the smooth diffusion of reactant and product molecules with larger molecular volumes, effectively preventing the occurrence of side reactions.

[0023] According to the present invention, preferably, based on the total weight of the novel catalyst, the content of the ZSM-5 molecular sieve is 40-60% by weight, the content of the SBA-16 all-silica mesoporous molecular sieve is 32-50% by weight, the content of the first modified oxide is 1-6% by weight, and the content of the second modified oxide is 2-9% by weight; more preferably, based on the total weight of the novel catalyst, the content of the ZSM-5 molecular sieve is 45-55% by weight, the content of the SBA-16 all-silica mesoporous molecular sieve is 35- The content of the first modified oxide is 1.5-3.5% by weight, and the content of the second modified oxide is 3.5-8.5% by weight, based on the total weight of the novel catalyst. More preferably, the content of the ZSM-5 molecular sieve is 46.7-54.6% by weight, the content of the SBA-16 all-silica mesoporous molecular sieve is 35.7-45.9% by weight, the content of the first modified oxide is 1.6-3.5% by weight, and the content of the second modified oxide is 3.9-8.1% by weight. In this invention, by using the aforementioned specific content of each component, the prepared cracking catalyst can have better catalytic activity and higher low-carbon olefin selectivity when used for the direct conversion of waste plastics to produce low-carbon olefins.

[0024] According to the present invention, the inventors use a mixture of ZSM-5 molecular sieve and SBA-16 all-silica mesoporous molecular sieve with a silicon-to-aluminum molar ratio (Si / Al) of 50-500 as the main active component, and introduce oxides as a modifying component, thereby improving both catalyst activity and low-carbon olefin selectivity. Preferably, when the silicon-to-aluminum molar ratio of the ZSM-5 zeolite molecular sieve is 100-300, both catalyst activity and low-carbon olefin selectivity are significantly improved.

[0025] According to the present invention, the first oxide may be one or more of non-metallic oxides or metal-like oxides, preferably one or more of boron oxide or phosphorus pentoxide.

[0026] According to the present invention, the second oxide is selected from one or more of alkaline earth metal oxides, transition metal oxides and rare earth metal oxides; preferably, the second oxide is selected from one or more of magnesium oxide, calcium oxide, strontium oxide, barium oxide, zinc oxide, copper oxide, cobalt oxide, cerium oxide, lanthanum oxide and zirconium dioxide.

[0027] According to the present invention, the specific surface area of ​​the SBA-16 all-silica mesoporous molecular sieve is 600-1000 m². 2 / g, pore volume of 0.4-1.0 mLg, and average pore size of 5-8 nm; preferably, the specific surface area of ​​the SBA-16 all-silica mesoporous molecular sieve is 700-900 m² / g. 2The SBA-16 all-silica mesoporous molecular sieve has a pore volume of 0.5-0.8 mL / g and an average pore size of 5.5-7.5 nm; more preferably, the specific surface area of ​​the SBA-16 is 749-853 m² / g. 2 The pore volume is 0.6-0.7 mL / g, and the average pore size is 6.0-7.0 nm. In this invention, the use of SBA-16 all-silica mesoporous molecular sieve with the aforementioned specific parameters enables the prepared cracking catalyst to exhibit better catalytic activity and higher selectivity when used in the direct conversion of waste plastics to produce low-carbon olefins.

[0028] According to the present invention, the preparation method of the SBA-16 all-silica mesoporous molecular sieve includes:

[0029] (1) Mix the template agent, acidic aqueous solution, n-butanol and chitosan to obtain a mixture;

[0030] (2) The mixture is reacted with a silicon source, then allowed to stand for crystallization and separation to obtain a solid product;

[0031] (3) The solid product is washed, dried and calcined to obtain SBA-16 all-silica mesoporous molecular sieve.

[0032] According to the present invention, the template agent can be an amphoteric triblock polymer, preferably F127 (polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer, molecular formula EO). 106 PO 70 EO 106 ).

[0033] According to the present invention, the acidic aqueous solution can be an inorganic acid aqueous solution, preferably one or more of dilute hydrochloric acid or dilute nitric acid, more preferably dilute hydrochloric acid; the concentration of the acidic aqueous solution can be 0.2-10%, preferably 0.5-3%.

[0034] According to the present invention, the silicon source can be an organic silicon-containing compound or an inorganic silicon-containing compound, preferably one or more of methyl orthosilicate, ethyl orthosilicate, isopropyl orthosilicate or silica sol, and more preferably ethyl orthosilicate.

[0035] According to the present invention, the weight ratio of the template agent: acidic aqueous solution: n-butanol: chitosan: silicon source can be 1:(10-200):(0.2-10):(0.05-1.0):(1-8), preferably 1:(20-100):(0.5-3):(0.1-0.5):(2-4).

[0036] According to the present invention, the mixing conditions include: a stirring rate of 50-300 r / min, a temperature of 20-60°C, and a time of 0.5-6 h; preferably, the stirring rate is 150-250 r / min, the temperature is 20-40°C, and the time is 0.5-3 h.

[0037] According to the present invention, the conditions for the reaction to occur in the contact can be a temperature of 50-150°C, preferably 80-120°C; and a time of 3-40 h, preferably 10-20 h.

[0038] According to the present invention, the conditions for static crystallization can be a temperature of 50-150°C, preferably 80-120°C; and a time of 10-48h, preferably 16-30h.

[0039] And / or, the contact conditions include: a temperature of 50-150°C and a time of 3-40 hours;

[0040] And / or, the crystallization conditions include: a temperature of 50-150°C and a time of 10-48 hours;

[0041] And / or, the calcination conditions include: a temperature of 400-700℃ and a time of 2-24h.

[0042] According to the present invention, there are no special requirements for the solid-liquid two-phase separation process, and it 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 vacuum flask to create a vacuum at the bottom of a funnel or using a centrifugal filter.

[0043] According to the present invention, there are no special requirements for the method of washing the solid product. For example, deionized water can be used to wash the solid product, the volume ratio of deionized water to solid product can be 5-20, and the number of washing cycles can be 2-8.

[0044] According to the present invention, the drying conditions can be a temperature of 80-150°C, preferably 100-130°C; and a time of 2-30 hours, preferably 5-20 hours.

[0045] According to the present invention, the calcination conditions can be a temperature of 400-700℃, preferably 500-600℃; and a time of 2-24h, preferably 4-12h.

[0046] A second aspect of the present invention provides a method for preparing the aforementioned novel catalyst, wherein the preparation method comprises:

[0047] ZSM-5 molecular sieve and SBA-16 all-silica mesoporous molecular sieve were mixed with an aqueous solution of modified components and reacted in contact; then, after dehydration, drying and calcination, a novel catalyst was obtained.

[0048] The modified component aqueous solution comprises an acid, a metal salt, and water; the acid is phosphoric acid and / or boric acid; the metal salt is selected from one or more nitrates of magnesium, calcium, strontium, barium, zinc, copper, cobalt, cerium, lanthanum, and zirconium, preferably one or more of calcium nitrate, barium nitrate, and magnesium nitrate hexahydrate.

[0049] According to the present invention, the mass concentration of the modified component aqueous solution can be 1-20%, preferably 2-10%.

[0050] According to the present invention, the weight ratio of the ZSM-5 molecular sieve, the SBA-16 all-silica mesoporous molecular sieve and the modified component aqueous solution is 1:(0.3-1.6):(3-30), preferably 1:(0.5-1.3):(6-20).

[0051] According to the present invention, the conditions for the contact reaction include: a temperature of 10-100°C, preferably 30-80°C; and a time of 0.5-50 h, preferably 2-20 h. Preferably, to achieve better mixing, rapid stirring or ultrasonic means can be used to improve mixing efficiency during the mixing of ZSM-5 molecular sieve, SBA-16 all-silica mesoporous molecular sieve, and the modified component aqueous solution.

[0052] According to the present invention, the water removal method is not particularly limited and can be any water removal method known in the art, such as using a rotary evaporator to evaporate water or using a heating and stirring method to remove water.

[0053] According to the present invention, the drying conditions include: a temperature of 60-150°C, preferably 80-130°C; and a time of 1-30 hours, preferably 3-20 hours.

[0054] According to the present invention, the calcination conditions include: a temperature of 400-700℃, preferably 500-600℃; and a time of 2-20h, preferably 3-10h.

[0055] A third aspect of the present invention provides the application of the aforementioned novel catalyst in the direct conversion of waste plastics to low-carbon olefins.

[0056] According to the present invention, the application includes: reacting plastic powder with the novel catalyst.

[0057] And / or, the contact conditions include: a temperature of 420-580℃, a pressure of 0.01-1MPa, and a contact time of 0.5-12h;

[0058] And / or, the weight ratio of the novel catalyst to the waste plastic powder is 1:(0.5-50).

[0059] In this invention, the contact conditions between the waste plastic powder and the novel catalyst include: the contact temperature can be 420-580℃, preferably 450-540℃; the contact pressure can be 0.01-1.0 MPa, preferably 0.05-0.5 MPa; the contact time can be 0.5-12 h, preferably 1-5 h; and the weight ratio of the novel catalyst to the waste plastic powder can be 1:0.5-50, preferably 1:2-30.

[0060] The present invention will be described in detail below through embodiments.

[0061] In the following examples and comparative examples:

[0062] Small-angle XRD tests of the samples were performed on a BRUKER AXS D8 ADVANCE high-power rotating target X-ray diffractometer, with a scanning range of 0.5-10°.

[0063] Wide-angle XRD tests of the samples were performed on a Philips X'Pert MPD X-ray powder diffractometer with a Cu Kα target and a scanning range of 2θ = 5-90°.

[0064] The pore structure parameters of the samples were analyzed using an ASAP2020-M+C adsorption analyzer manufactured by Micromeritics, USA. Before measurement, the samples were degassed under vacuum at 350℃ for 4 hours. The specific surface area of ​​the samples was calculated using the BET method, and the pore volume was calculated using the BJH model.

[0065] Elemental analysis of the samples was performed on an Eagle III energy-dispersive X-ray fluorescence spectrometer manufactured by EDAX Corporation in the United States.

[0066] The rotary evaporator was manufactured by IKA GmbH in Germany, model RV10digital.

[0067] The drying oven was manufactured by Shanghai Yiheng Scientific Instruments Co., Ltd., model DHG-9030A.

[0068] The muffle furnace is manufactured by CARBOLITE, model CWF1100.

[0069] The ZSM-5 molecular sieves with different silica-to-alumina ratios used in the examples and comparative examples were all purchased from Nankai Catalyst Factory; other reagents used in the examples and comparative examples were all purchased from Sinopharm Chemical Reagent Co., Ltd., and the reagent purity was analytical grade.

[0070] Example 1

[0071] (1) Preparation of SBA-16 all-silica mesoporous molecular sieve

[0072] In a 1000ml round-bottom flask, add 10g of polyether F127, 20g of concentrated hydrochloric acid, and 500ml of deionized water, and mix and stir at room temperature for 30 minutes. Continue by adding 15g of n-butanol and 2g of chitosan to the flask, and stir for 1 hour. Slowly add 25g of tetraethyl orthosilicate, raise the temperature to 100℃, and stir and react for 16 hours. Then, allow the mixture to crystallize at 100℃ for 24 hours. After crystallization, filter to obtain a white solid product, wash 8 times with deionized water, dry in air at 120℃ for 10 hours, and then calcine at 550℃ for 8 hours to obtain SBA-16 mesoporous molecular sieve A.

[0073] The specific surface area of ​​SBA-16 all-silica mesoporous molecular sieve A is 794 m². 2 / g, pore volume 0.65cm³ 3 / g, with an average pore size of 6.5nm.

[0074] (2) Preparation of novel catalysts

[0075] 3.6 g of phosphoric acid and 17.6 g of calcium nitrate were dissolved in 400 g of distilled water to prepare an aqueous solution of the modified component. 51 g of ZSM-5 molecular sieve (Si / Al = 200) and 42 g of SBA-16 all-silica mesoporous molecular sieve A were added to the above aqueous solution of the modified component. After stirring at 60 °C for 5 h, the 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 the novel catalyst A.

[0076] Figure 1 This is the small-angle XRD pattern of catalyst A. The pattern shows that the sample exhibits a strong diffraction signal corresponding to the (110) crystal plane in the range of 2θ = 0.5°-1°, indicating that the SBA-16 all-silica mesoporous molecular sieve still has a relatively regular mesoporous channel structure after being prepared into a catalyst, and the catalyst preparation process did not destroy the basic structure of the mesoporous molecular sieve.

[0077] Figure 2 This is the wide-angle XRD pattern of catalyst A. The pattern shows that the main X-ray diffraction angles of this sample are: 2θ = 8.0°, 8.8°, 14.8°, 23.0°, and 24.0°. These five diffraction signals are consistent with the diffraction pattern of ZSM-5 molecular sieve, indicating that the ZSM-5 molecular sieve in catalyst A still maintains its typical MFI crystal phase structure, and the catalyst preparation process did not destroy the basic structure of the ZSM-5 molecular sieve. No diffraction signals corresponding to the modified oxides appear in the wide-angle XRD pattern, indicating that the modified components are uniformly dispersed on the catalyst.

[0078] The specific surface area, pore volume, and composition of catalyst A are listed in Table 1.

[0079] (3) Evaluation of the reaction performance of direct conversion of waste plastics to low-carbon olefins

[0080] The performance of the catalyst in the catalytic cracking of methyl tert-butyl ether was evaluated in a fixed-bed reactor. The catalyst loading was 10.0 g, the polypropylene waste plastic loading was 60.0 g, the reaction temperature was 500℃, the reaction pressure was 0.1 MPa, and the reaction time was 2 hours. After product cooling and gas-liquid separation, the gas composition was analyzed using an Agilent 6890 gas chromatograph equipped with an Al2O3-S capillary column and a flame ionization detector (FID), with programmed temperature ramping and quantitative analysis using correction factors. The liquid composition was analyzed using an Agilent 6890 gas chromatograph equipped with a PONA column. The reaction results are shown in Table 2.

[0081] Example 2

[0082] (1) Preparation of SBA-16 all-silica mesoporous molecular sieve

[0083] In a 1000ml round-bottom flask, add 10g of polyether F127 and 200g of 3% dilute hydrochloric acid, and mix and stir at room temperature for 30 minutes. Continue by adding 5g of n-butanol and 1g of chitosan to the flask, and stir for 1 hour. Slowly add 20g of tetraethyl orthosilicate, raise the temperature to 80℃, and stir and react for 20 hours. Then, allow the mixture to crystallize at 80℃ for 30 hours. After crystallization, filter to obtain a white solid product, wash six times with deionized water, dry in air at 100℃ for 20 hours, and then calcine at 500℃ for 12 hours to obtain SBA-16 mesoporous molecular sieve B.

[0084] The specific surface area of ​​SBA-16 mesoporous molecular sieve B is 853 m². 2 / g, pore volume 0.7cm³ 3 / g, with an average pore size of 6.0nm.

[0085] (2) Preparation of novel catalysts

[0086] 2.8 g of boric acid and 50.8 g of magnesium nitrate hexahydrate were dissolved in 600 g of distilled water to prepare an aqueous solution of the modified component. 55 g of ZSM-5 molecular sieve (Si / Al = 300) and 36 g of SBA-16 all-silica mesoporous molecular sieve B were added to the above aqueous solution of the modified component. After stirring at 80 °C for 2 h, the 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 the novel catalyst B.

[0087] The specific surface area, pore volume, and composition of catalyst B are listed in Table 1.

[0088] The reaction performance of catalyst B was tested according to the reaction performance evaluation method for direct conversion of waste plastics to low-carbon olefins in step (3) of Example 1. The evaluation results are listed in Table 2.

[0089] Example 3

[0090] (1) Preparation of SBA-16 all-silica mesoporous molecular sieve

[0091] In a 2000ml round-bottom flask, 10g of polyether F127 and 200g of 0.5% dilute hydrochloric acid were added and stirred at room temperature for 30 minutes. Then, 30g of n-butanol and 5g of chitosan were added, and the mixture was stirred for 1 hour. 40g of tetraethyl orthosilicate was slowly added, and the temperature was raised to 120℃. After stirring and reacting for 10 hours, the mixture was allowed to crystallize at 120℃ for 16 hours. After crystallization, the product was filtered to obtain a white solid product, washed 8 times with deionized water, dried in air at 130℃ for 5 hours, and then calcined at 600℃ for 4 hours to obtain SBA-16 mesoporous molecular sieve C.

[0092] The specific surface area of ​​SBA-16 mesoporous molecular sieve C is 749 m². 2 / g, pore volume 0.6cm³ 3 / g, with an average pore size of 7.0nm.

[0093] (2) Preparation of novel catalysts

[0094] 4.8 g of phosphoric acid and 6.7 g of barium nitrate were dissolved in 300 g of distilled water to prepare an aqueous solution of the modified component. 47 g of ZSM-5 molecular sieve (Si / Al = 100) and 46 g of SBA-16 all-silica mesoporous molecular sieve C were added to the above aqueous solution of the modified component. After stirring at 30 °C for 20 h, the water was removed using a rotary evaporator. The solid product was dried at 80 °C for 20 h and then calcined at 500 °C for 10 h to obtain the novel catalyst C.

[0095] The specific surface area, pore volume, and composition of catalyst C are listed in Table 1.

[0096] The reaction performance of catalyst C was tested according to the reaction performance evaluation method for direct conversion of waste plastics to low-carbon olefins in step (3) of Example 1. The evaluation results are listed in Table 2.

[0097] Example 4

[0098] SBA-16 all-silica mesoporous molecular sieve A was prepared according to the method in step (1) of Example 1.

[0099] The novel catalyst D was prepared according to step (2) of Example 1. The preparation conditions were changed, and the specific process is as follows:

[0100] 1.4 g of phosphoric acid and 26.4 g of calcium nitrate were dissolved in 400 g of distilled water to prepare an aqueous solution of the modified component. 40 g of ZSM-5 molecular sieve (Si / Al = 200) and 50 g of SBA-16 all-silica mesoporous molecular sieve A were added to the above aqueous solution of the modified component. After stirring at 60 °C for 5 h, the 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 the novel catalyst D.

[0101] The specific surface area, pore volume, and composition of catalyst D are listed in Table 1.

[0102] The reaction performance of catalyst D was tested according to the reaction performance evaluation method for direct conversion of waste plastics to low-carbon olefins in step (3) of Example 1. The evaluation results are listed in Table 2.

[0103] Example 5

[0104] SBA-16 all-silica mesoporous molecular sieve B was prepared according to the method in step (1) of Example 2.

[0105] The novel catalyst E was prepared according to step (2) of Example 2. The preparation conditions were changed, and the specific process is as follows:

[0106] 10.6 g of boric acid and 12.8 g of magnesium nitrate hexahydrate were dissolved in 600 g of distilled water to prepare an aqueous solution of the modified component. 60 g of ZSM-5 molecular sieve (Si / Al = 100) and 32 g of SBA-16 all-silica mesoporous molecular sieve B were added to the above aqueous solution of the modified component. After stirring at 80 °C for 2 h, the 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 the novel catalyst E.

[0107] The specific surface area, pore volume, and composition of catalyst E are listed in Table 1.

[0108] The reaction performance of catalyst E was tested according to the reaction performance evaluation method for direct conversion of waste plastics to low-carbon olefins in step (3) of Example 1. The evaluation results are listed in Table 2.

[0109] Example 6

[0110] SBA-16 all-silica mesoporous molecular sieve A was prepared according to the method in step (1) of Example 1.

[0111] The novel catalyst F was prepared according to step (2) of Example 1. The preparation conditions were changed, and the specific process is as follows:

[0112] 0.7 g of phosphoric acid and 35.2 g of calcium nitrate were dissolved in 400 g of distilled water to prepare an aqueous solution of the modified component. 35 g of ZSM-5 molecular sieve (Si / Al = 200) and 52.5 g of SBA-16 all-silica mesoporous molecular sieve A were added to the above aqueous solution of the modified component. After stirring at 60 °C for 5 h, the 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 the novel catalyst F.

[0113] The specific surface area, pore volume, and composition of catalyst F are listed in Table 1.

[0114] The reaction performance of catalyst F was tested according to the reaction performance evaluation method for direct conversion of waste plastics to low-carbon olefins in step (3) of Example 1. The evaluation results are listed in Table 2.

[0115] Example 7

[0116] SBA-16 all-silica mesoporous molecular sieve B was prepared according to the method in step (1) of Example 2.

[0117] The novel catalyst G was prepared according to step (2) of Example 2. The preparation conditions were changed, and the specific process is as follows:

[0118] 14.1 g of boric acid and 6.4 g of magnesium nitrate hexahydrate were dissolved in 600 g of distilled water to prepare an aqueous solution of the modified component. 65 g of ZSM-5 molecular sieve (Si / Al = 100) and 26 g of SBA-16 all-silica mesoporous molecular sieve B were added to the above aqueous solution of the modified component. After stirring at 80 °C for 2 h, the 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 the novel catalyst G.

[0119] The specific surface area, pore volume, and composition of catalyst G are listed in Table 1.

[0120] The reaction performance of catalyst G was tested according to the reaction performance evaluation method for direct conversion of waste plastics to low-carbon olefins in step (3) of Example 1, and the evaluation results are listed in Table 2.

[0121] Comparative Example 1

[0122] SBA-16 all-silica mesoporous molecular sieve A was prepared according to the method in step (1) of Example 1.

[0123] The novel catalyst D1 was prepared according to the method in step (2) of Example 1. The preparation conditions were changed, and the specific process is as follows:

[0124] 0.1 g of phosphoric acid and 66.0 g of zinc nitrate hexahydrate were dissolved in 400 g of distilled water to prepare an aqueous solution of the modified component. 16 g of ZSM-5 molecular sieve (Si / Al = 200) and 87 g of SBA-16 all-silica mesoporous molecular sieve A were added to the above aqueous solution of the modified component. After stirring at 60 °C for 5 h, the 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 the novel catalyst D1.

[0125] The specific surface area, pore volume, and composition of catalyst D1 are listed in Table 1.

[0126] The reaction performance of catalyst D1 was tested according to the reaction performance evaluation method for direct conversion of waste plastics to low-carbon olefins in step (3) of Example 1. The evaluation results are listed in Table 2.

[0127] Comparative Example 2

[0128] SBA-16 all-silica mesoporous molecular sieve B was prepared according to the method in step (1) of Example 2.

[0129] The novel catalyst D2 was prepared according to step (2) of Example 2. The preparation conditions were changed, and the specific process is as follows:

[0130] 24.8 g of boric acid and 1.8 g of copper nitrate hexahydrate were dissolved in 500 g of distilled water to prepare an aqueous solution of the modified component. 74 g of ZSM-5 molecular sieve (Si / Al = 100) and 12 g of SBA-16 all-silica mesoporous molecular sieve B were added to the above aqueous solution of the modified component. After stirring at 80 °C for 2 h, the 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 the novel catalyst D2.

[0131] The specific surface area, pore volume, and composition of catalyst D2 are listed in Table 1.

[0132] The reaction performance of catalyst D2 was tested according to the reaction performance evaluation method for direct conversion of waste plastics to low-carbon olefins in step (3) of Example 1. The evaluation results are listed in Table 2.

[0133] Comparative Example 3

[0134] SBA-16 all-silica mesoporous molecular sieve B was prepared according to the method in step (1) of Example 2.

[0135] The novel catalyst D3 was prepared according to step (2) of Example 1. The preparation conditions were changed, and ZSM-5 molecular sieve was not used. The specific process is as follows:

[0136] 3.6 g of phosphoric acid and 17.6 g of calcium nitrate were dissolved in 400 g of distilled water to prepare an aqueous solution of the modified component. 92 g of SBA-16 all-silica mesoporous molecular sieve B was added to the above aqueous solution of the modified component. After stirring at 60 °C for 5 h, the 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 the novel catalyst D3.

[0137] The specific surface area, pore volume, and composition of catalyst D3 are listed in Table 1.

[0138] The reaction performance of catalyst D3 was tested according to the reaction performance evaluation method for direct conversion of waste plastics to low-carbon olefins in step (3) of Example 1. The evaluation results are listed in Table 2.

[0139] Comparative Example 4

[0140] The novel catalyst D4 was prepared according to step (2) of Example 1. The preparation conditions were changed, and SBA-16 all-silica mesoporous molecular sieve was not used. The specific process is as follows:

[0141] 3.6 g of phosphoric acid and 17.6 g of calcium nitrate were dissolved in 400 g of distilled water to prepare an aqueous solution of the modified component. 92 g of ZSM-5 molecular sieve (Si / Al = 200) was added to the above aqueous solution of the modified component. After stirring at 60 °C for 5 h, the 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 the novel catalyst D4.

[0142] The specific surface area, pore volume, and composition of catalyst D4 are listed in Table 1.

[0143] The reaction performance of catalyst D4 was tested according to the reaction performance evaluation method for direct conversion of waste plastics to low-carbon olefins in step (3) of Example 1. The evaluation results are listed in Table 2.

[0144] Comparative Example 5

[0145] SBA-16 all-silica mesoporous molecular sieve A was prepared according to the method in step (1) of Example 1.

[0146] The novel catalyst D5 was prepared according to step (2) of Example 1. The preparation conditions were changed, and the first modifying component was not added. The specific process is as follows:

[0147] 25.2 g of calcium nitrate was dissolved in 400 g of distilled water to prepare an aqueous solution of the modified component. 51 g of ZSM-5 molecular sieve (Si / Al = 200) and 42 g of SBA-16 all-silica mesoporous molecular sieve A were added to the above aqueous solution of the modified component. After stirring at 60 °C for 5 h, the 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 the novel catalyst D5.

[0148] The specific surface area, pore volume, and composition of catalyst D5 are listed in Table 1.

[0149] The reaction performance of catalyst D5 was tested according to the reaction performance evaluation method for direct conversion of waste plastics to low-carbon olefins in step (3) of Example 1. The evaluation results are listed in Table 2.

[0150] Comparative Example 6

[0151] SBA-16 all-silica mesoporous molecular sieve B was prepared according to the method in step (1) of Example 2.

[0152] The novel catalyst D6 was prepared according to step (2) of Example 1. The preparation conditions were changed, and the second modifying component was not added. The specific process is as follows:

[0153] 11.9 g of phosphoric acid was dissolved in 400 g of distilled water to prepare an aqueous solution of the modified component. 51 g of ZSM-5 molecular sieve (Si / Al = 100) and 42 g of SBA-16 all-silica mesoporous molecular sieve B were added to the above aqueous solution of the modified component. After stirring at 60 °C for 5 h, the 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 the novel catalyst D6.

[0154] The specific surface area, pore volume, and composition of catalyst D6 are listed in Table 1.

[0155] The reaction performance of catalyst D6 was tested according to the reaction performance evaluation method for direct conversion of waste plastics to low-carbon olefins in step (3) of Example 1. The evaluation results are listed in Table 2.

[0156] Comparative Example 7

[0157] SBA-16 all-silica mesoporous molecular sieve A was prepared according to the method in step (1) of Example 1.

[0158] The novel catalyst D7 was prepared according to step (2) of Example 1. The preparation conditions were changed, and the first and second modifying components were not added. The specific process is as follows:

[0159] 55g of ZSM-5 molecular sieve (Si / Al = 200) and 45g of SBA-16 all-silica mesoporous molecular sieve A were mixed with 400g of distilled water and stirred at 60℃ for 5h. The water was removed by rotary evaporator, the solid product was dried at 110℃ for 8h, and then calcined at 550℃ for 6h to obtain the novel catalyst D7.

[0160] The specific surface area, pore volume, and composition of catalyst D7 are listed in Table 1.

[0161] The reaction performance of catalyst D7 was tested according to the reaction performance evaluation method for direct conversion of waste plastics to low-carbon olefins in step (3) of Example 1. The evaluation results are listed in Table 2.

[0162] Comparative Example 8

[0163] SBA-16 all-silica mesoporous molecular sieve A was prepared according to the method in step (1) of Example 1.

[0164] The novel catalyst D8 was prepared according to step (2) of Example 1. The preparation conditions were changed, and the second modified oxide was replaced with sodium oxide, as follows:

[0165] 3.6 g of phosphoric acid and 16.5 g of calcium nitrate were dissolved in 400 g of distilled water to prepare an aqueous solution of the modified component. 51 g of ZSM-5 molecular sieve (Si / Al = 200) and 42 g of SBA-16 all-silica mesoporous molecular sieve A were added to the above aqueous solution of the modified component. After stirring at 60 °C for 5 h, the 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 the novel catalyst D8.

[0166] The specific surface area, pore volume, and composition of catalyst D8 are listed in Table 1.

[0167] The reaction performance of catalyst D8 was tested according to the reaction performance evaluation method for direct conversion of waste plastics to low-carbon olefins in step (3) of Example 1. The evaluation results are listed in Table 2.

[0168] Table 1

[0169]

[0170]

[0171]

[0172] Table 2

[0173]

[0174]

[0175] The results above demonstrate that the novel catalyst provided by this invention can directly catalytically convert waste plastics into low-carbon olefins. The waste plastic conversion rate is 100%, and the low-carbon olefin yield is high.

[0176] In Comparative Example 1, the content of SBA-16 all-silica mesoporous molecular sieve was too high, the content of ZSM-5 molecular sieve was too low, and the content of modified components was not within the scope of the claims. Due to the limited number of acidic centers on the catalyst and insufficient activation sites during the reaction, the feed conversion rate and the yield of low-carbon olefins were low.

[0177] In Comparative Example 2, the content of SBA-16 all-silica mesoporous molecular sieve was too low, the content of ZSM-5 molecular sieve was too high, and the content of the modified component was not within the scope of the claims. Due to the limited number of macropores in the catalyst, the diffusion of reactant and product molecules was hindered during the reaction, resulting in a low yield of low-carbon olefins.

[0178] In Comparative Example 3, the catalyst contained only SBA-16 all-silica mesoporous molecular sieve, without ZSM-5 molecular sieve. Due to the near absence of acidic centers on the catalyst and the severe lack of activation sites during the reaction, the feed conversion rate was very low and the yield of low-carbon olefins was also low.

[0179] In Comparative Example 4, the catalyst contained only ZSM-5 molecular sieve and no SBA-16 all-silica mesoporous molecular sieve. Because the catalyst contained almost no large-pore channels, the diffusion of reactant and product molecules was severely hindered during the reaction, resulting in a low yield of low-carbon olefins.

[0180] In Comparative Example 5, the catalyst contained only the second modified oxide and no first modified oxide, resulting in a lower yield of low-carbon olefins.

[0181] In Comparative Example 6, the catalyst contained only the first modified oxide and no second modified oxide, resulting in a lower yield of low-carbon olefins.

[0182] In Comparative Example 7, the catalyst did not contain modified oxides, resulting in a lower yield of low-carbon olefins.

[0183] In Comparative Example 8, sodium oxide was used instead of the second modified oxide specifically defined in this invention. Due to the lower modification effect of sodium oxide of the same weight, the yield of low-carbon olefins was lower.

[0184] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. The application of a novel catalyst in the direct conversion of waste plastics to low-carbon olefins, the application including: The reaction involves contacting plastic powder with a novel catalyst, characterized in that the plastic powder is waste polypropylene plastic, and the novel catalyst comprises ZSM-5 molecular sieve, SBA-16 all-silica mesoporous molecular sieve, a first modified oxide, and a second modified oxide. Based on the total weight of the novel catalyst, the content of ZSM-5 molecular sieve is 40-60% by weight, the content of SBA-16 all-silica mesoporous molecular sieve is 32-50% by weight, the content of the first modified oxide is 1-6% by weight, and the content of the second modified oxide is 2-9% by weight; the specific surface area of ​​the SBA-16 all-silica mesoporous molecular sieve is 600-1000 m² / g. 2 / g, pore volume is 0.4-1.0mL / g, and average pore size is 5-8nm; The preparation method of the novel catalyst includes: ZSM-5 molecular sieve and SBA-16 all-silica mesoporous molecular sieve were mixed with an aqueous solution of modified components and reacted in contact; then, after dehydration, drying and calcination, a novel catalyst was obtained. The modified component aqueous solution comprises an acid, a metal salt, and water; the acid is phosphoric acid and / or boric acid, and the metal salt is selected from one or more nitrates selected from magnesium, calcium, strontium, barium, zinc, copper, cobalt, cerium, lanthanum, and zirconium.

2. The application according to claim 1, wherein, Based on the total weight of the novel catalyst, the content of the ZSM-5 molecular sieve is 45-55% by weight, the content of the SBA-16 all-silica mesoporous molecular sieve is 35-46% by weight, the content of the first modified oxide is 1.5-3.5% by weight, and the content of the second modified oxide is 3.5-8.5% by weight.

3. The application according to claim 1 or 2, wherein, The silicon-aluminum molar ratio (Si / Al) of the ZSM-5 molecular sieve is 50-500.

4. The application according to claim 3, wherein, The silicon-aluminum molar ratio (Si / Al) of the ZSM-5 molecular sieve is 100-300.

5. The application according to claim 1, wherein, The specific surface area of ​​the SBA-16 all-silica mesoporous molecular sieve is 700-900 m². 2 / g, pore volume is 0.5-0.8mL / g, and average pore size is 5.5-7.5nm.

6. The application according to claim 5, wherein, The specific surface area of ​​the SBA-16 all-silica mesoporous molecular sieve is 749-853 m². 2 / g, pore volume is 0.6-0.7mL / g, and average pore size is 6.0-7.0nm.

7. The application according to claim 1 or 2, wherein, The preparation method of the SBA-16 all-silica mesoporous molecular sieve includes: (1) Mix the template agent, acidic aqueous solution, n-butanol and chitosan to obtain a mixture; (2) The mixture is reacted with a silicon source, then allowed to stand, crystallize, and separate to obtain a solid product; (3) The solid product is washed, dried and calcined to obtain SBA-16 all-silica mesoporous molecular sieve.

8. The application according to claim 7, wherein, The weight ratio of the template agent, acidic aqueous solution, n-butanol, chitosan, and silicon source can be 1:(10-200):(0.2-10):(0.05-1.0):(1-8). And / or, the contact conditions include: a temperature of 50-150°C and a time of 3-40 hours; And / or, the crystallization conditions include: a temperature of 50-150°C and a time of 10-48 hours; And / or, the calcination conditions include: a temperature of 400-700℃ and a time of 2-24h.

9. The application according to claim 1, wherein, The metal salt is selected from one or more of calcium nitrate, barium nitrate, and magnesium nitrate hexahydrate.

10. The application according to claim 1, wherein, The mass concentration of the modified component aqueous solution is 1-20%; The weight ratio of the ZSM-5 molecular sieve, the SBA-16 all-silica mesoporous molecular sieve, and the modified component aqueous solution is 1:(0.3-1.6):(3-30). The conditions for the contact reaction include: a temperature of 10-100℃ and a time of 0.5-50h; The roasting conditions include: a temperature of 400-700℃ and a time of 2-20h.

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

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