CN110819372B

CN110819372B - Method for preparing aromatic hydrocarbon and hydrogen-rich fuel gas by catalytic thermal conversion of polyolefin waste plastic

Info

Publication number: CN110819372B
Application number: CN201910979991.5A
Authority: CN
Inventors: 袁浩然; 程磊磊; 顾菁; 陈勇
Original assignee: Guangzhou Institute of Energy Conversion of CAS
Current assignee: Guangzhou Institute of Energy Conversion of CAS
Priority date: 2019-10-15
Filing date: 2019-10-15
Publication date: 2022-02-25
Anticipated expiration: 2039-10-15
Also published as: CN110819372A

Abstract

The invention discloses a method for preparing aromatic hydrocarbon and hydrogen-rich fuel gas by catalytic thermal conversion of polyolefin waste plastics. The method comprises the following steps: feeding pretreated polyolefin waste plastic into a reaction container, adopting a metal-loaded zeolite molecular sieve as a catalyst, wherein the mass ratio of the polyolefin waste plastic to the catalyst is 5-30: 1, introducing nitrogen into the reaction container, keeping the reaction system sealed when the initial nitrogen pressure in the reaction container is 1-30 bar, heating the reaction container to 320-500 ℃, stopping heating, cooling the reaction container to normal temperature, collecting a gas product and a solid-liquid product in the reaction container, collecting the gas product through a gas collection tank, collecting the catalyst and residues of reaction raw materials through a filter by the solid-liquid product, and further treating the obtained liquid product. The invention takes polyolefin waste plastic as raw material, directionally prepares aromatic hydrocarbon compound by catalytic thermal conversion, and takes the aromatic hydrocarbon compound as chemical raw material for production and processing, thus being an effective waste plastic resource utilization method.

Description

Method for preparing aromatic hydrocarbon and hydrogen-rich fuel gas by catalytic thermal conversion of polyolefin waste plastic

Technical Field

The invention relates to the technical field of resource recycling, in particular to a method for preparing aromatic hydrocarbon and hydrogen-rich fuel gas by catalytic thermal conversion of polyolefin waste plastics.

Background

As a daily product with huge yield, plastic brings great treatment pressure because the plastic is difficult to degrade. Statistics show that only 9% of plastic waste is recycled, 12% is incinerated, and 79% is dumped into land and marine ecosystems by landfilling or dumping. Not only causes the waste of land resources and the pollution of soil, water quality and atmospheric environment, but also loses the opportunity of resource utilization.

Proportion of waste plastics in the household garbage-polyethylene: polypropylene: polystyrene: polyvinyl chloride: the other 48:18:16:7:11, the waste of polyolefin plastics (mainly polyethylene and polypropylene) accounts for 66%, and is an important component in waste plastics. Pyrolysis technology has become a hot research point in the field of plastic waste disposal, and the target product is fuel oil or chemical raw materials, including hydrocarbons such as alkane, olefin and aromatic hydrocarbon. At present, a fuel oil product obtained by pyrolyzing waste plastics is difficult to meet the operation requirement of an engine and lacks reasonable application. Accordingly, the prior art is in need of improvement and development.

Disclosure of Invention

The invention provides a method for preparing aromatic hydrocarbon and hydrogen-rich fuel gas by catalytic thermal conversion of polyolefin waste plastic, which takes the polyolefin waste plastic as a raw material, directionally prepares an aromatic hydrocarbon compound by catalytic thermal conversion, and takes the aromatic hydrocarbon compound as a chemical raw material for production and processing, thereby being an effective waste plastic resource utilization method.

The invention aims to provide a method for preparing aromatic hydrocarbon and hydrogen-rich fuel gas by catalytic thermal conversion of polyolefin waste plastics, which comprises the following steps: feeding pretreated polyolefin waste plastic into a reaction container, introducing nitrogen into the reaction container by using a metal-loaded zeolite molecular sieve as a catalyst, wherein the metal is selected from one of zinc, gallium, iron, molybdenum and cobalt, the mass ratio of the polyolefin waste plastic to the catalyst is 5-30: 1, keeping the reaction system closed when the initial nitrogen pressure in the reaction container is 1-30 bar, heating the reaction container to 320-500 ℃, stopping heating, cooling the reaction container to normal temperature, collecting a gas product and a solid-liquid product in the reaction container, collecting the gas product through a gas collection tank, collecting the catalyst and residues of reaction raw materials through a filter by using the solid-liquid product, and further treating the obtained liquid product.

The long polyolefin chains are broken in the reactor by heating to generate shorter hydrocarbon chains. The small molecular olefin or the precursor thereof obtained by pyrolysis is subjected to secondary reaction-diene synthesis to further generate the cyclic olefin, and the cyclic olefin is subjected to two-step dehydrogenation reaction to generate the aromatic hydrocarbon. And cyclizing part of the olefin or the precursor thereof to obtain cycloalkane or cycloalkene, and further carrying out dehydrogenation reaction on the cycloalkane or cycloalkene to generate the aromatic hydrocarbon. Therefore, the obtained gas product has low olefin content and high hydrogen and small molecular alkane gas content.

Compared with the common noble metal supported catalyst, the zeolite molecular sieve catalyst supported by non-noble metals is used, so that the catalyst cost is reduced. The aromatic hydrocarbon content in the liquid product obtained by the invention is higher than that of other similar thermal conversion technologies, the coke yield is low, and the gas product is rich in hydrogen and micromolecular alkane gas.

Preferably, the nitrogen pressure is 1-15 bar.

Preferably, the metal-supported zeolite molecular sieve catalyst is prepared by the following steps: and (2) putting the metal salt solution into a water bath container at the temperature of 50-80 ℃, adding the zeolite molecular sieve into the metal salt solution, soaking until the water is evaporated to dryness, drying at the temperature of 100-150 ℃ for 6-15 h, and roasting at the temperature of 500-600 ℃ for 3-6 h to obtain the metal-loaded zeolite molecular sieve catalyst. Zeolite molecular sieve catalysts include ZSM-5, ZSM-11, and the like.

Preferably, the metal loading is 1-5 wt.%. Further preferably, the metal loading is 1-3 wt.%.

Preferably, the method for preparing aromatic hydrocarbon and hydrogen-rich fuel gas by catalytic thermal conversion of polyolefin waste plastics comprises the following steps: feeding pretreated polyolefin waste plastic into a reaction container, adopting a metal zinc-loaded zeolite molecular sieve as a catalyst, wherein the mass ratio of the polyolefin waste plastic to the catalyst is 10-20: 1, introducing nitrogen into the reaction container, keeping the reaction system sealed when the initial nitrogen pressure in the reaction container is 1-15 bar, heating the reaction container to 340-450 ℃, stopping heating, cooling the reaction container to normal temperature, collecting a gas product and a solid-liquid product in the reaction container, collecting the gas product through a gas collection tank, collecting the catalyst and residues of reaction raw materials through a filter from the solid-liquid product, and further treating the obtained liquid product.

Preferably, the pretreatment of the pretreated polyolefin waste plastic comprises the following steps: collecting polyolefin waste plastics, removing impurities and drying to obtain pretreated polyolefin waste plastics, wherein the polyolefin is polyethylene or polypropylene.

Preferably, the liquid product comprises monocyclic aromatic hydrocarbon, bicyclic aromatic hydrocarbon and low-carbon alkane, and the monocyclic aromatic hydrocarbon comprises toluene, benzene, xylene and ethylbenzene. The liquid product mainly comprises more than 90% of monocyclic aromatic hydrocarbon (mainly comprising toluene, benzene, xylene, ethylbenzene and the like), a small amount of bicyclic aromatic hydrocarbon and low-carbon alkane, and the obtained liquid product is further purified according to industrial requirements and then used. The gas product mainly comprises components such as hydrogen, methane, ethane and propane, the percentage is more than 80%, the content of the micromolecule olefin gas is low, and the gas product is used as high-quality fuel gas for plant area heat supply or power generation. The catalyst obtained by filtering the filter is reused after being regenerated by cleaning, drying and the like.

Compared with the prior art, the invention has the beneficial effects that:

(1) the liquid product obtained by the method has high yield, wherein the content of the monocyclic aromatic hydrocarbon can reach more than 90 wt.%, and the yield of the target product is higher than that of other similar thermal conversion technologies.

(2) The method has the advantages of low coke yield, less carbon deposition of the catalyst and capability of repeatedly using the catalyst for about 10 times.

(3) Compared with the common noble metal supported catalyst, the zeolite molecular sieve catalyst supported by non-noble metals is used, so that the catalyst cost is reduced.

(4) According to the requirements of target products, the invention can achieve the purpose of regulating the product yield and product distribution by regulating the operation parameters (temperature, pressure and catalyst metal loading).

Drawings

FIG. 1 is a schematic structural diagram of a device for preparing aromatic hydrocarbons and hydrogen-rich fuel gas by catalytic thermal conversion of polyolefin waste plastics;

description of reference numerals: 1. a screw conveyor; 2. a nitrogen tank; 3. an air delivery pump; 4. an intake valve; 5. a magnetic stirrer; 6. an autoclave reactor; 7. an electric heating jacket; 8. a filter; 9. a liquid outlet valve; 10. a pressure gauge; 11. an air outlet valve; 12. a gas collection tank; 13. a temperature controller.

Detailed Description

The following examples are further illustrative of the present invention and are not intended to be limiting thereof.

In the following examples, the apparatus for preparing aromatic hydrocarbons and hydrogen-rich fuel gas by catalytic thermal conversion of polyolefin waste plastics as shown in fig. 1 is used to realize the catalytic thermal conversion of polyolefin waste plastics to prepare aromatic hydrocarbons and hydrogen-rich fuel gas, and specifically, the apparatus includes an autoclave reactor 6, the temperature rise rate of the autoclave reactor 6 is set to be 5-30 ℃/min, the bottom of the outside of the autoclave reactor 6 is provided with an electric heating jacket 7, the outside of the autoclave reactor 6 is further provided with a temperature controller 13, the top of the autoclave reactor 6 is provided with a gas inlet, a gas outlet and a feed inlet, polyolefin waste plastics conveyed by a screw conveyor 1 are placed into the autoclave reactor 6 through the feed inlet, the bottom of the autoclave reactor 6 is provided with a liquid outlet, and the autoclave reactor 6 is further provided with a magnetic stirrer 5 and a catalyst module. The nitrogen gas stored in the nitrogen gas tank 2 is transferred to the autoclave reactor 6 through the gas inlet by the gas transfer pump 3, and when the gas inlet valve 4 is opened to introduce the nitrogen gas, the initial pressure of the nitrogen gas in the autoclave reactor is determined by the indication of the pressure gauge 10. After the reaction is finished, the gas outlet valve 11 is opened, high-pressure gas is conveyed into the gas collecting tank 12 through the gas outlet through the high-pressure gas conveying pipeline, liquid products are filtered out of catalysts and collected after carbon precipitation through the liquid outlet by the filter 8, the obtained liquid products are discharged through the liquid outlet valve 9, the liquid products are rich in monocyclic aromatic hydrocarbons such as toluene, benzene and xylene, the monocyclic aromatic hydrocarbons are further purified and used according to different industrial requirements, and the catalysts collected in the filter are regenerated and reused.

The metal-loaded zeolite molecular sieve catalyst is prepared by the following steps: and (2) putting the metal salt solution into a water bath container at the temperature of 50-80 ℃, adding the zeolite molecular sieve into the metal salt solution, soaking until the water is evaporated to dryness, drying at the temperature of 100-150 ℃ for 6-15 h, and roasting at the temperature of 500-600 ℃ for 3-6 h to obtain the metal-loaded zeolite molecular sieve catalyst.

Example 1

Feeding pretreated polyethylene into an autoclave reactor by using a device shown in figure 1, adopting 3 wt.% zinc-loaded ZSM-5 as a catalyst, wherein the mass ratio of a polyethylene raw material to the catalyst is 15:1, purging with nitrogen to remove air in the autoclave, closing a gas outlet on the autoclave, continuously introducing nitrogen, enabling the initial nitrogen pressure to be 1bar (namely, under the condition of no pressurization), closing the autoclave reactor, setting the temperature rise rate of the autoclave reactor to be 15 ℃/min, heating the autoclave reactor to 380 ℃, and then stopping heating. After the high-pressure autoclave reactor is cooled to normal temperature by air, firstly opening an air outlet valve of the high-pressure autoclave reactor, collecting a gas product by using an air bag, then opening a liquid outlet valve of the reactor to collect a liquid product, and filtering and collecting the catalyst and a solid product by using a filter.

The 2 wt.% zinc-supported zeolite molecular sieve catalyst was prepared by the following steps: putting a zinc nitrate solution into a 70 ℃ water bath container, adding zeolite molecular sieve ZSM-5 into a zinc chloride solution, soaking until water is evaporated to dryness, drying at 120 ℃ for 10h, and roasting at 550 ℃ for 3h to obtain the 2 wt.% zinc-loaded zeolite molecular sieve catalyst.

The mass of liquid and solid products is obtained by weighing respectively, the mass of gas product is obtained by subtraction, and the product yield is calculated. The gas product composition was determined using Gas Chromatography (GC) and comparison to standard gas, and the liquid product composition was determined using a gas chromatography-mass spectrometer. The product yields, liquid compositions, and gas compositions obtained are shown in table 1:

TABLE 1

Comparative example 1

The same as example 1, except that: ZSM-5 without supported metal is used as a catalyst. The product yields, liquid product compositions, and gaseous product compositions obtained were collected as shown in table 2:

TABLE 2

As can be seen from a comparison of tables 1 and 2, catalytic thermal conversion using a ZSM-5 catalyst not loaded with zinc produced more coke and gaseous products than the zinc loaded ZSM-5 catalyst used in example 1. The liquid product not only has low yield, but also contains more low-value polycyclic aromatic hydrocarbon, and the content of monocyclic aromatic hydrocarbon is reduced.

Comparative example 2

The same as example 1, except that: ZSM-5 supported on 2 wt.% nickel was used as the catalyst. The product yields, liquid product compositions, and gaseous product compositions obtained were collected as shown in table 3:

TABLE 3

As can be seen from the comparison of tables 1 and 3, catalytic thermal conversion using a nickel-supported ZSM-5 catalyst produced more coke and gaseous products than the zinc-supported ZSM-5 catalyst used in example 1. The liquid product has low yield, high polycyclic aromatic hydrocarbon content and low monocyclic aromatic hydrocarbon content.

Comparative example 3

The same as example 1, except that: biochar is used as a catalyst. The product yields, liquid product compositions, and gaseous product compositions obtained were collected as shown in table 4:

TABLE 4

As shown by the comparison of tables 1 and 4, compared with the zinc-loaded ZSM-5 catalyst used in example 1, the content of aromatic hydrocarbon, which is the target product obtained by catalytic thermal conversion using the biochar catalyst, is greatly reduced because the acid strength of the biochar catalyst is weaker than that of the zeolite molecular sieve catalyst. In addition, the hydrogen content in the obtained fuel gas is correspondingly reduced.

Example 2

Feeding pretreated polyethylene into an autoclave reactor by using a device shown in fig. 1, using 5 wt.% of zinc-loaded ZSM-5 as a catalyst (the step of the zinc-loaded zeolite molecular sieve catalyst is the same as that in example 1), wherein the mass ratio of the polyethylene raw material to the catalyst is 10:1, purging nitrogen to remove air in the autoclave, closing a gas outlet on the autoclave, continuously introducing nitrogen to make the initial nitrogen pressure to 10bar, closing the autoclave reactor, setting the temperature rise rate of the autoclave reactor to be 15 ℃/min, heating the autoclave reactor to 450 ℃, and then stopping heating. After the high-pressure reactor is cooled to normal temperature by air, firstly opening an air outlet valve of the high-pressure reactor to collect a gas product, then opening a liquid outlet valve of the reactor to collect a liquid product, and filtering and collecting the catalyst and the solid product through a filter.

The mass of liquid and solid products is obtained by weighing respectively, the mass of gas product is obtained by subtraction, and the product yield is calculated. The gas product composition was determined using Gas Chromatography (GC) and comparison to standard gas, and the liquid product composition was determined using a gas chromatography-mass spectrometer. The product yields, liquid compositions, and gas compositions obtained are shown in Table 5:

TABLE 5

Example 3

Feeding pretreated polyethylene into an autoclave reactor by using a device shown in fig. 1, using 1 wt.% zinc-loaded ZSM-5 as a catalyst (the step of the zinc-loaded zeolite molecular sieve catalyst is the same as that in example 1), wherein the mass ratio of the polyethylene raw material to the catalyst is 20:1, purging nitrogen to remove air in the autoclave, closing a gas outlet on the autoclave, continuously introducing nitrogen to make the initial nitrogen pressure to 15bar, closing the autoclave reactor, setting the temperature rise rate of the autoclave reactor to 15 ℃/min, heating the autoclave reactor to 340 ℃, and then stopping heating. After the high-pressure reactor is cooled to normal temperature by air, firstly opening an air outlet valve of the high-pressure reactor to collect a gas product, then opening a liquid outlet valve of the reactor to collect a liquid product, and filtering and collecting the catalyst and the solid product through a filter.

The mass of liquid and solid products is obtained by weighing respectively, the mass of gas product is obtained by subtraction, and the product yield is calculated. The gas product composition was determined using Gas Chromatography (GC) and comparison to standard gas, and the liquid product composition was determined using a gas chromatography-mass spectrometer. The product yields, liquid compositions, and gas compositions obtained are shown in Table 6:

TABLE 6

Example 4

Feeding pretreated polyethylene into an autoclave reactor by using a device shown in figure 1, adopting 3 wt.% zinc-loaded ZSM-5 as a catalyst (the step of the zinc-loaded zeolite molecular sieve catalyst is the same as that in example 1), wherein the mass ratio of the polyethylene raw material to the catalyst is 20:1, after air in the autoclave is completely removed by nitrogen purging, closing a gas outlet on the autoclave, continuously introducing nitrogen to ensure that the initial nitrogen pressure is 7bar, closing the autoclave reactor, setting the temperature rise rate of the autoclave reactor to be 15 ℃/min, heating the autoclave reactor to 420 ℃, and then stopping heating. After the high-pressure reactor is cooled to normal temperature by air, firstly opening an air outlet valve of the high-pressure reactor to collect a gas product, then opening a liquid outlet valve of the reactor to collect a liquid product, and filtering and collecting the catalyst and the solid product through a filter.

The mass of liquid and solid products is obtained by weighing respectively, the mass of gas product is obtained by subtraction, and the product yield is calculated. The gas product composition was determined using Gas Chromatography (GC) and comparison to standard gas, and the liquid product composition was determined using a gas chromatography-mass spectrometer. The product yields, liquid compositions, and gas compositions obtained are shown in Table 7:

TABLE 7

Example 5

Feeding pretreated polyethylene into an autoclave reactor by using a device shown in figure 1, adopting 3 wt.% zinc-loaded ZSM-5 as a catalyst (the step of the zinc-loaded zeolite molecular sieve catalyst is the same as that in example 1), wherein the mass ratio of the polyethylene raw material to the catalyst is 15:1, after air in the autoclave is completely removed by nitrogen purging, closing a gas outlet on the autoclave, continuously introducing nitrogen to ensure that the initial nitrogen pressure is 5bar, closing the autoclave reactor, setting the temperature rise rate of the autoclave reactor to be 15 ℃/min, heating the autoclave reactor to 400 ℃, and then stopping heating. After the high-pressure reactor is cooled to normal temperature by air, firstly opening an air outlet valve of the high-pressure reactor to collect a gas product, then opening a liquid outlet valve of the reactor to collect a liquid product, and filtering and collecting the catalyst and the solid product through a filter.

The mass of liquid and solid products is obtained by weighing respectively, the mass of gas product is obtained by subtraction, and the product yield is calculated. The gas product composition was determined using Gas Chromatography (GC) and comparison to standard gas, and the liquid product composition was determined using a gas chromatography-mass spectrometer. The product yields, liquid compositions, and gas compositions obtained are shown in Table 8:

TABLE 8

Example 6

Feeding pretreated polyethylene into an autoclave reactor by using a device shown in figure 1, taking 5 wt.% zinc-loaded ZSM-11 as a catalyst, controlling the mass ratio of the polyethylene raw material to the catalyst to be 30:1, purging the autoclave with nitrogen to remove air, closing a gas outlet on the autoclave, continuously introducing nitrogen to ensure that the initial nitrogen pressure is 30bar, closing the autoclave reactor, setting the temperature rise rate of the autoclave reactor to be 5 ℃/min, heating the autoclave reactor to 320 ℃, and then stopping heating. After the high-pressure reactor is cooled to normal temperature by air, firstly opening an air outlet valve of the high-pressure reactor to collect a gas product, then opening a liquid outlet valve of the reactor to collect a liquid product, and filtering and collecting the catalyst and the solid product through a filter.

The mass of liquid and solid products is obtained by weighing respectively, the mass of gas product is obtained by subtraction, and the product yield is calculated. The gas product composition was determined using Gas Chromatography (GC) and comparison to standard gas, and the liquid product composition was determined using a gas chromatography-mass spectrometer. The product yields, liquid compositions, and gas compositions obtained are shown in Table 9:

TABLE 9

Example 7

Feeding pretreated polyethylene into an autoclave reactor by using a device shown in figure 1, taking 1 wt.% zinc-loaded ZSM-11 as a catalyst, wherein the mass ratio of the polyethylene raw material to the catalyst is 5:1, purging with nitrogen to remove air in the autoclave, closing a gas outlet on the autoclave, continuously introducing nitrogen to enable the initial nitrogen pressure to be 1bar, closing the autoclave reactor, setting the temperature rise rate of the autoclave reactor to be 30 ℃/min, heating the autoclave reactor to 500 ℃, and then stopping heating. After the high-pressure reactor is cooled to normal temperature by air, firstly opening an air outlet valve of the high-pressure reactor to collect a gas product, then opening a liquid outlet valve of the reactor to collect a liquid product, and filtering and collecting the catalyst and the solid product through a filter.

The mass of liquid and solid products is obtained by weighing respectively, the mass of gas product is obtained by subtraction, and the product yield is calculated. The gas product composition was determined using Gas Chromatography (GC) and comparison to standard gas, and the liquid product composition was determined using a gas chromatography-mass spectrometer. The product yields, liquid compositions, and gas compositions obtained are shown in Table 10:

watch 10

The above is only a preferred embodiment of the present invention, and it should be noted that the above preferred embodiment should not be considered as limiting the present invention, and the protection scope of the present invention should be subject to the scope defined by the claims. It will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the spirit and scope of the invention, and these modifications and adaptations should be considered within the scope of the invention.

Claims

1. A method for preparing aromatic hydrocarbon and hydrogen-rich fuel gas by polyolefin waste plastic catalytic thermal conversion is characterized by comprising the following steps: feeding pretreated polyolefin waste plastic into a reaction container, introducing nitrogen into the reaction container by using a metal zinc-loaded zeolite molecular sieve as a catalyst, keeping the reaction system closed when the initial nitrogen pressure in the reaction container is 1-15 bar, heating the reaction container to 340-450 ℃, stopping heating, cooling the reaction container to normal temperature, collecting a gas product and a solid-liquid product in the reaction container, collecting the catalyst and residues of reaction raw materials by a gas collection tank, and further treating the obtained liquid product; the zeolite molecular sieve catalyst loaded with the metal zinc is prepared by the following steps: putting a metal zinc salt solution into a water bath container at 50-80 ℃, adding a zeolite molecular sieve into the metal zinc salt solution, soaking until the water is evaporated to dryness, drying at 100-150 ℃ for 6-15 h, and roasting at 500-600 ℃ for 3-6 h to obtain a metal zinc-loaded zeolite molecular sieve catalyst, wherein the zeolite molecular sieve is ZSM-5 or ZSM-11, and the polyolefin is polyethylene;

the method is realized by a device for preparing aromatic hydrocarbon and hydrogen-rich gas by catalytic thermal conversion of polyolefin waste plastics, the device specifically comprises an autoclave reactor, the heating rate of the autoclave reactor is set to be 5-30 ℃/min, the bottom of the outer side of the autoclave reactor is provided with an electric heating sleeve, the outer side of the autoclave reactor is also provided with a temperature controller, the top of the autoclave reactor is provided with a gas inlet, a gas outlet and a feed inlet, the polyolefin waste plastics conveyed by a screw conveyor are placed into the autoclave reactor through the feed inlet, the bottom of the autoclave reactor is provided with a liquid outlet, the autoclave reactor is also internally provided with a magnetic stirrer and a catalyst module, nitrogen stored in a nitrogen tank is conveyed to the autoclave reactor through the gas inlet by a gas transmission pump, and when an air inlet valve is opened and nitrogen is introduced, the initial pressure of the nitrogen in the autoclave reactor is determined by the indication of a pressure gauge, after the reaction is finished, the gas outlet valve is opened, high-pressure gas is conveyed into the gas collecting tank through the gas outlet through the high-pressure gas conveying pipeline, liquid products are collected after the liquid products are filtered out of catalysts and carbon is separated through the liquid outlet through the filter, the obtained liquid products are discharged through the liquid outlet valve, the liquid products are further purified according to different industrial requirements and then used, and the catalysts collected in the filter are reused after regeneration.

2. The method for preparing aromatic hydrocarbon and hydrogen-rich fuel gas by catalytic thermal conversion of polyolefin waste plastic as claimed in claim 1, wherein the pretreatment of the pretreated polyolefin waste plastic comprises the following steps: collecting polyolefin waste plastics, removing impurities and drying to obtain the pretreated polyolefin waste plastics.

3. The method for preparing aromatic hydrocarbon and hydrogen-rich fuel gas by catalytic thermal conversion of polyolefin waste plastic according to claim 1, wherein the liquid product comprises monocyclic aromatic hydrocarbon, bicyclic aromatic hydrocarbon and low-carbon alkane, and the monocyclic aromatic hydrocarbon comprises toluene, benzene, xylene and ethylbenzene.