CN115072659A - Method for preparing hydrogen by polyethylene plastic - Google Patents
Method for preparing hydrogen by polyethylene plastic Download PDFInfo
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- CN115072659A CN115072659A CN202210849086.XA CN202210849086A CN115072659A CN 115072659 A CN115072659 A CN 115072659A CN 202210849086 A CN202210849086 A CN 202210849086A CN 115072659 A CN115072659 A CN 115072659A
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- thermal cracking
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- polyethylene plastic
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- 229910052739 hydrogen Inorganic materials 0.000 title claims abstract description 99
- 239000001257 hydrogen Substances 0.000 title claims abstract description 98
- -1 polyethylene Polymers 0.000 title claims abstract description 91
- 239000004698 Polyethylene Substances 0.000 title claims abstract description 90
- 229920000573 polyethylene Polymers 0.000 title claims abstract description 90
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 title claims abstract description 88
- 229920003023 plastic Polymers 0.000 title claims abstract description 77
- 239000004033 plastic Substances 0.000 title claims abstract description 77
- 238000000034 method Methods 0.000 title claims abstract description 41
- 238000004227 thermal cracking Methods 0.000 claims abstract description 86
- 239000003054 catalyst Substances 0.000 claims abstract description 84
- 230000003197 catalytic effect Effects 0.000 claims abstract description 72
- 238000006356 dehydrogenation reaction Methods 0.000 claims abstract description 62
- 238000004519 manufacturing process Methods 0.000 claims abstract description 21
- 239000002994 raw material Substances 0.000 claims abstract description 18
- 239000007789 gas Substances 0.000 claims description 82
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 56
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 34
- 239000006229 carbon black Substances 0.000 claims description 31
- 229910052742 iron Inorganic materials 0.000 claims description 25
- 238000001179 sorption measurement Methods 0.000 claims description 25
- 239000007769 metal material Substances 0.000 claims description 24
- 239000003575 carbonaceous material Substances 0.000 claims description 22
- 229910052723 transition metal Inorganic materials 0.000 claims description 21
- 150000003624 transition metals Chemical class 0.000 claims description 21
- 239000000203 mixture Substances 0.000 claims description 20
- 230000008569 process Effects 0.000 claims description 16
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 12
- 150000002431 hydrogen Chemical class 0.000 claims description 8
- 238000000746 purification Methods 0.000 claims description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 5
- 239000011358 absorbing material Substances 0.000 claims description 4
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 3
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 3
- 239000000969 carrier Substances 0.000 claims description 2
- 229910001567 cementite Inorganic materials 0.000 claims description 2
- SZVJSHCCFOBDDC-UHFFFAOYSA-N ferrosoferric oxide Chemical compound O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 claims description 2
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 claims description 2
- 239000010453 quartz Substances 0.000 claims description 2
- 229910001220 stainless steel Inorganic materials 0.000 claims description 2
- 239000010935 stainless steel Substances 0.000 claims description 2
- 239000013502 plastic waste Substances 0.000 abstract description 16
- 229910052799 carbon Inorganic materials 0.000 abstract description 8
- 230000003993 interaction Effects 0.000 abstract description 4
- 238000002360 preparation method Methods 0.000 abstract description 3
- 230000008929 regeneration Effects 0.000 abstract description 2
- 238000011069 regeneration method Methods 0.000 abstract description 2
- 239000000047 product Substances 0.000 description 78
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 48
- 238000010438 heat treatment Methods 0.000 description 25
- 229910052757 nitrogen Inorganic materials 0.000 description 23
- 239000000843 powder Substances 0.000 description 22
- 238000004458 analytical method Methods 0.000 description 20
- 239000012159 carrier gas Substances 0.000 description 14
- 238000005336 cracking Methods 0.000 description 14
- 229910052751 metal Inorganic materials 0.000 description 13
- 239000002184 metal Substances 0.000 description 13
- 238000006243 chemical reaction Methods 0.000 description 12
- 238000011068 loading method Methods 0.000 description 12
- 238000006555 catalytic reaction Methods 0.000 description 11
- 238000005070 sampling Methods 0.000 description 11
- 238000005406 washing Methods 0.000 description 11
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 8
- 238000002156 mixing Methods 0.000 description 8
- 229930195733 hydrocarbon Natural products 0.000 description 5
- 238000000926 separation method Methods 0.000 description 5
- 239000004215 Carbon black (E152) Substances 0.000 description 4
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 229910052786 argon Inorganic materials 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 150000002430 hydrocarbons Chemical class 0.000 description 4
- 239000011261 inert gas Substances 0.000 description 4
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical compound [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 238000001354 calcination Methods 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 238000003795 desorption Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000003463 adsorbent Substances 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 2
- 238000011065 in-situ storage Methods 0.000 description 2
- 239000013067 intermediate product Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000000197 pyrolysis Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- XTEGARKTQYYJKE-UHFFFAOYSA-M Chlorate Chemical class [O-]Cl(=O)=O XTEGARKTQYYJKE-UHFFFAOYSA-M 0.000 description 1
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 239000004793 Polystyrene Substances 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005285 chemical preparation method Methods 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 238000009841 combustion method Methods 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000012634 fragment Substances 0.000 description 1
- 238000004868 gas analysis Methods 0.000 description 1
- 238000002309 gasification Methods 0.000 description 1
- 229910021389 graphene Inorganic materials 0.000 description 1
- 238000005470 impregnation Methods 0.000 description 1
- 229920002521 macromolecule Polymers 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002808 molecular sieve Substances 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 150000002902 organometallic compounds Chemical class 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 229920006255 plastic film Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 229920000915 polyvinyl chloride Polymers 0.000 description 1
- 239000004800 polyvinyl chloride Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000005201 scrubbing Methods 0.000 description 1
- 239000000741 silica gel Substances 0.000 description 1
- 229910002027 silica gel Inorganic materials 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 1
- 239000011232 storage material Substances 0.000 description 1
- 239000010923 used plastic bag Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
- C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
- C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
- C01B3/22—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by decomposition of gaseous or liquid organic compounds
- C01B3/24—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by decomposition of gaseous or liquid organic compounds of hydrocarbons
- C01B3/26—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by decomposition of gaseous or liquid organic compounds of hydrocarbons using catalysts
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
- C01B2203/04—Integrated processes for the production of hydrogen or synthesis gas containing a purification step for the hydrogen or the synthesis gas
- C01B2203/0415—Purification by absorption in liquids
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
- C01B2203/04—Integrated processes for the production of hydrogen or synthesis gas containing a purification step for the hydrogen or the synthesis gas
- C01B2203/042—Purification by adsorption on solids
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
- C01B2203/10—Catalysts for performing the hydrogen forming reactions
- C01B2203/1041—Composition of the catalyst
- C01B2203/1047—Group VIII metal catalysts
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
- C01B2203/10—Catalysts for performing the hydrogen forming reactions
- C01B2203/1041—Composition of the catalyst
- C01B2203/1082—Composition of support materials
Abstract
The invention belongs to the field of energy regeneration, and particularly discloses a method for producing hydrogen by using polyethylene plastic as a raw material. The method takes polyethylene plastics, particularly polyethylene plastic waste as raw materials, and comprises the steps of continuously performing microwave thermal cracking and microwave catalytic treatment. The efficient and low-carbon hydrogen production method based on the microwave technology realizes high-selectivity and efficient dehydrogenation treatment through the interaction of the catalyst and the microwave, and realizes the preparation of high-purity hydrogen from polyethylene plastic.
Description
Technical Field
The invention belongs to the field of energy regeneration, and particularly relates to a method for producing hydrogen by using polyethylene plastic as a raw material.
Background
Polyethylene is a high molecular polymer and is also a common plastic in daily life. Although there are many types of plastics, such as polyethylene, polypropylene, polyvinyl chloride, polystyrene, etc., the amount of polyethylene plastic used accounts for about 30% of the amount of plastic products commonly used in daily life, and is large. The polyethylene plastic products which we are familiar with include widely used plastic bags, plastic films, plastic boxes and the like. The polyethylene plastic product has short service life, the service cycle is 1-3 months generally, and then the polyethylene plastic product is discarded. The polyethylene plastic waste has large production amount, is difficult to recycle and has low recycling value. At present, polyethylene plastic waste is mostly treated by adopting an incineration method, and the traditional incineration treatment has the defects of high emission and high pollution.
Polyethylene plastic is also a solid raw material rich in hydrogen elements, and the hydrogen content of the polyethylene plastic is about 14.2 percent, so that the polyethylene plastic is a good hydrogen storage material. However, since polyethylene has a stable high molecular structure, it is difficult to achieve selective dehydrogenation treatment. Therefore, it is highly desirable to develop a method for producing hydrogen from polyethylene plastic to make high-value use of polyethylene plastic waste.
Disclosure of Invention
The invention aims to provide a method for preparing hydrogen by using polyethylene plastics, in particular polyethylene plastic waste, which can prepare high-purity hydrogen, can continuously carry out the preparation process and does not generate harmful gases such as carbon dioxide and the like in the preparation process.
Specifically, the method for preparing hydrogen by using polyethylene plastics provided by the invention uses the polyethylene plastics as a raw material to prepare hydrogen, and comprises two continuous sections of treatment; wherein:
the first stage of treatment is microwave thermal cracking of polyethylene plastic to produce thermal cracking product;
the second stage treatment is that the thermal cracking product is subjected to microwave catalytic treatment to generate hydrogen-containing gas;
wherein, the catalyst adopted by the microwave catalytic treatment is selected from carbon materials, transition metal materials or transition metal materials taking carbon materials as carriers.
In some embodiments, the transition metal material is a ferrous metal material.
In some preferred embodiments, the transition metal material is selected from one or more of metallic iron, ferrous oxide, ferric oxide, ferroferric oxide, and iron carbide.
In some embodiments, the carbon material is carbon black, activated carbon, or silicon carbide.
In some preferred embodiments, the carbon material is carbon black.
In some embodiments, the catalyst employed in the present invention is a mixture of a carbon material and the transition metal material or a carbon material supported transition metal material.
In some embodiments, the catalyst comprises a transition metal material and a carbon material in a mass ratio of (1-99): 1, and preferably comprises a transition metal material and a carbon material in a mass ratio of (4-19): 1.
According to a specific embodiment, the catalyst comprises a transition metal material and a carbon material in a mass ratio of (2-9): 1. According to a specific embodiment, the catalyst comprises a transition metal material and a carbon material in a mass ratio of (3-9): 1. According to a specific embodiment, the catalyst comprises a transition metal material and a carbon material in a mass ratio of (4-9): 1. According to a specific embodiment, the catalyst comprises a transition metal material and a carbon material in a mass ratio of 4:1, 5:1, 6:1, 7:1, 8:1, 9: 1.
In some embodiments, the catalyst employed in the present invention is a mixture of carbon black and iron oxide, or a carbon black supported metallic iron catalyst.
More preferably, the catalyst employed in the present invention is a carbon black supported metallic iron catalyst.
In some embodiments, the temperature for microwave thermal cracking is 450 to 800 ℃, preferably 500 to 750 ℃, and more preferably 500 to 550 ℃.
In some embodiments, the power of the microwave catalytic treatment is 100 to 6000W, preferably 1000 to 4000W, for example 1000W, 2000W, 3000W or 4000W, more preferably 3000 to 4000W.
In some embodiments, the microwave frequency of the microwave thermal cracking and the microwave catalytic treatment is 2.45GHz or 915MHz, preferably 2.45 GHz.
In some embodiments, the microwave catalytic treatment is performed for 20 to 60 minutes.
In some embodiments, the microwave thermal cracking and the microwave catalytic treatment employ a microwave thermal cracking reactor and a microwave catalytic dehydrogenation reactor in series.
Preferably, the catalyst in the microwave catalytic dehydrogenation reactor is preheated during microwave thermal cracking. And introducing a reaction product obtained by microwave thermal cracking into the preheated microwave catalytic dehydrogenation reactor for microwave catalytic treatment.
According to some embodiments of the present disclosure, the mass ratio of the catalyst loaded in the microwave catalytic dehydrogenation reactor to the polyethylene plastic is 1 (5-100). According to a specific embodiment, the mass ratio of the catalyst to the polyethylene plastic can be 1 (5-90), 1 (5-80), 1 (5-70), 1 (5-60), 1 (5-50), 1 (5-40), 1 (5-30), 1 (5-20), and 1 (5-15). For example, the mass ratio of the catalyst to the polyethylene plastic can be 1 (10-15).
In some embodiments, the method for producing hydrogen from polyethylene plastic provided by the present invention further comprises an operation of performing separation and purification on the hydrogen-containing gas, and the separation and purification method may adopt a method known in the art.
In some embodiments, the separation purification comprises a scrubbing and/or Pressure Swing Adsorption (PSA) treatment. Pressure swing adsorption generally refers to adsorption under pressure at a constant temperature, desorption under reduced pressure (vacuum) or atmospheric pressure, i.e., adsorption and desorption by varying the pressure. In the present disclosure, pressure swing adsorption means, in particular, adsorption and desorption are performed using periodic variation of pressure based on the difference in selective adsorption capacity of an adsorbent for hydrogen and other gases at different pressures, thereby achieving separation and purification of hydrogen.
According to some embodiments of the present disclosure, the adsorbent comprises one or more of carbon, alumina, silica gel, molecular sieves, silica, graphene.
Before microwave thermal cracking treatment, the polyethylene plastic raw material can be pretreated according to actual conditions, wherein the pretreatment comprises drying treatment and/or crushing treatment.
According to some embodiments of the present disclosure, the microwave thermal cracking and/or microwave catalytic dehydrogenation treatment steps are performed under oxygen-free or low oxygen conditions (e.g., an inert environment with an oxygen content of less than 5000 ppm). According to a specific embodiment, during the microwave thermal cracking and/or microwave catalytic dehydrogenation treatment, an inert gas is introduced, for example nitrogen or argon.
The present invention also provides an apparatus for producing hydrogen gas, the apparatus comprising:
the microwave thermal cracking reactor is used for carrying out microwave thermal cracking treatment to generate a thermal cracking product;
the microwave catalytic dehydrogenation reactor is used for carrying out microwave treatment on the thermal cracking product in the presence of a catalyst to generate hydrogen-containing gas; and
a first gas collection tank for collecting the hydrogen-containing gas product.
The microwave thermal cracking reactor and the microwave catalytic dehydrogenation reactor adopted by the invention can be microwave reactors carrying conventional microwave sources (including magnetron or solid sources).
In some embodiments, the inner wall of the thermal microwave cracking reactor is provided with a wave-absorbing material, such as a silicon carbide-based wave-absorbing material, and the maximum working temperature of the thermal microwave cracking reactor can reach 1600 ℃.
In some embodiments, the body of the microwave catalytic dehydrogenation reactor is made of quartz or stainless steel, and no wave-absorbing material is arranged in the wall of the reactor.
In some embodiments, the apparatus for producing hydrogen provided by the present invention further comprises:
the pressure swing adsorption unit is used for carrying out pressure swing adsorption purification on the hydrogen-containing gas to generate high-purity hydrogen; and
and the second gas collecting tank is used for collecting the high-purity hydrogen.
According to a specific embodiment, the method of the present disclosure may comprise: loading a catalyst in a microwave catalytic dehydrogenation reactor, setting the microwave power to be 500-4000W and 2.45GHz, heating the catalyst to be more than or equal to 350 ℃ under the condition of inert gas (nitrogen or argon), and stably maintaining the temperature; putting the crushed polyethylene plastic fragments into a microwave thermal cracking furnace, setting the thermal cracking temperature to be 450-800 ℃, and introducing inert gas (nitrogen or argon) to carry out thermal cracking on the plastic; introducing gas-liquid mixed hydrocarbon obtained by thermal cracking into a microwave catalytic dehydrogenation reactor through inert gas (carrier gas), and performing catalytic dehydrogenation treatment on the hydrocarbon through the interaction of a catalyst and microwaves to realize high-selectivity in-situ pyrolysis-catalytic dehydrogenation; the resulting gas product, which may pass through a scrubber bottle, is collected in a first vapor collection tank.
According to a specific embodiment, the gas product in the first gas collection tank enters a pressure swing adsorption unit to purify hydrogen to obtain a final hydrogen product, and the final hydrogen product is collected in the second gas collection tank.
In the present disclosure, the microwave thermal cracking reactor rapidly heats the polyethylene plastic by using microwaves, so as to achieve rapid cracking and gasification of the polyethylene plastic; the microwave catalytic dehydrogenation realizes the selective carbon-hydrogen bond fracture through the interaction of microwaves and a catalyst, and the high-purity hydrogen is prepared.
The invention provides a brand-new method for treating polyethylene plastic garbage, which can quickly and efficiently prepare high-purity hydrogen from polyethylene plastic. The method takes a microwave reactor as a reaction furnace, crude hydrogen with high hydrogen content is prepared from polyethylene plastics through microwave pyrolysis and microwave catalytic dehydrogenation, and high-purity hydrogen with the purity of more than 99 percent can be obtained through further pressure swing adsorption and purification. In the method, firstly, polyethylene plastic macromolecules are cracked into micromolecular gas-liquid mixed intermediate products through fast pyrolysis under microwave; and then introducing the intermediate products into a microwave catalytic dehydrogenation reaction furnace through carrier gas, and performing microwave catalytic dehydrogenation treatment on a mixed product obtained by microwave thermal cracking through the interaction of microwaves and a catalyst under the environment of standard atmospheric pressure, oxygen-free/low oxygen to obtain high-purity hydrogen-containing gas. Microwave thermal cracking is mainly based on the rapid heating characteristic of microwaves, thermal cracking of polyethylene plastics is realized, and small molecular hydrocarbons beneficial to subsequent catalytic dehydrogenation are obtained. In the microwave catalytic dehydrogenation treatment process, the in-situ high-selectivity hydrocarbon bond breakage is realized by instantaneous heating of the catalyst under microwaves, so that the catalytic dehydrogenation treatment of the hydrocarbon is improved. The hydrogen production method disclosed by the invention effectively improves the yield and purity of hydrogen. The hydrogen production method disclosed by the invention can be used for fully decomposing polyethylene plastics to prepare hydrogen, and does not generate carbon dioxide gas, so that the process is an energy-saving, environment-friendly and efficient process for treating plastic wastes and producing hydrogen. In addition, the method can continuously prepare high-purity hydrogen, and has important significance for industrial continuous production.
Drawings
FIG. 1 is a diagram of an apparatus used in a method for producing hydrogen from polyethylene plastic provided by the invention.
Detailed Description
The following examples and figures are provided to aid in the understanding of the present invention. It is to be understood that these examples and drawings are illustrative of the invention and are not to be construed as limiting in any way. The actual scope of the invention is set forth in the following claims. It is to be understood that any modifications and variations may be made without departing from the spirit of the invention.
The catalyst used in the present invention can be prepared by chemical preparation methods known in the art, such as an impregnation method, a precipitation method, a combustion method, and the like. For transition metal materials supported on carbon materials or iron-based metal materials supported on carbon materials, the metal may be mixed with the support material in the form of precursors including, but not limited to, nitrates, chlorates, organometallic compounds, and the like. In order to better ensure the effect of microwave absorption of the catalyst, the particle size of the catalyst adopted by the invention is less than 50 μm, and the particle size of the catalyst is preferably 50 nm-10 μm.
Fig. 1 illustrates an apparatus for preparing hydrogen from polyethylene plastic, which includes a microwave thermal cracking reactor (1), a microwave catalytic dehydrogenation reactor (2), a first gas collection tank, a pressure swing adsorption unit, and a second gas collection tank. In the process of preparing hydrogen, polyethylene plastic is put into a microwave thermal cracking reactor (1) for microwave thermal cracking; the obtained gas-liquid mixture enters a microwave catalytic dehydrogenation reactor (2) along with carrier gas, and microwave catalytic dehydrogenation treatment is carried out to obtain a product containing hydrogen; the obtained product containing hydrogen flows into a first gas collecting tank; then the hydrogen enters a pressure swing adsorption unit for separation and purification to obtain high-purity hydrogen, and the high-purity hydrogen is collected into a second gas collection tank.
Example 1
In the embodiment, the hydrogen production reaction is carried out by taking the polyethylene plastic waste as a raw material, and the process flow is shown in fig. 1, and specifically comprises the following steps:
(1) crushing 100g of polyethylene plastic, putting the crushed polyethylene plastic into a microwave thermal cracking reactor (1), introducing nitrogen (50mL/min), setting the heating rate at 20 ℃/min, heating to 500 ℃ and keeping the temperature, and thermally cracking the polyethylene plastic to generate a thermal cracking product;
(2) loading 10g of catalyst (prepared by mixing 325-mesh iron oxide powder and carbon black powder according to a mass ratio of 9: 1) into a microwave catalytic dehydrogenation reactor (2), setting the microwave power to be 1000W and the frequency to be 2.45GHz, starting the microwave catalytic dehydrogenation reactor (2) while opening the microwave thermal cracking reactor (1), and preheating the loaded catalyst;
(3) introducing the thermal cracking product obtained in the step (1) into a microwave catalytic dehydrogenation reactor (2) through nitrogen gas as a carrier gas, carrying out microwave catalytic reaction for 30 minutes under the conditions of microwave power of 1000W and frequency of 2.45GHz to generate a hydrogen-containing gas product, carrying out gas washing, collecting, sampling and analyzing, wherein the result is shown in Table 1; the gas product is further processed by Pressure Swing Adsorption (PSA), the gas is collected, and the sample is taken for analysis, so that the purity of the hydrogen reaches 99.9 percent.
TABLE 1 analysis results of gas products
| Composition (I) | Molar ratio of |
| H 2 | 72.3％ |
| CH 4 | 5.7％ |
| C 2+ | 2.9％ |
| CO | 15.6％ |
| CO 2 | 3.5％ |
The iron oxide powder in the catalyst in the embodiment is prepared by the following method: mixing ferric nitrate and citric acid according to a mass ratio of 1: 1, and calcining at 350 ℃ for 3 hours to obtain orange iron oxide powder.
Example 2
In the embodiment, the hydrogen production reaction is carried out by taking the polyethylene plastic waste as a raw material, and the process flow is shown in fig. 1, and specifically comprises the following steps:
(1) crushing 100g of polyethylene plastic, putting the crushed polyethylene plastic into a microwave thermal cracking reactor (1), introducing nitrogen (50mL/min), setting the heating rate at 20 ℃/min, heating to 550 ℃ and keeping the temperature, and thermally cracking the polyethylene plastic to generate a thermal cracking product;
(2) taking 10g of a catalyst (the catalyst is prepared by mixing 325-mesh iron oxide powder and carbon black powder according to a mass ratio of 9: 1) and loading the catalyst into a microwave catalytic dehydrogenation reactor (2), setting the microwave power to be 2000W and the frequency to be 2.45GHz, starting the microwave catalytic dehydrogenation reactor (2) while opening a microwave thermal cracking reactor (1), and preheating the loaded catalyst;
(3) introducing the thermal cracking product obtained in the step (1) into a microwave catalytic dehydrogenation reactor (2) through carrier gas nitrogen, carrying out microwave catalytic reaction for 30 minutes under the conditions of microwave power of 2000W and frequency of 2.45GHz to generate a hydrogen-containing gas product, carrying out gas washing, collecting, sampling and analyzing, wherein the result is shown in table 2; the gas product is further processed by Pressure Swing Adsorption (PSA), the gas is collected, and the sample is taken for analysis, so that the purity of the hydrogen reaches 99.9 percent.
TABLE 2 gas product analysis results
| Composition (I) | Molar ratio of |
| H 2 | 76.6％ |
| CH 4 | 4.3％ |
| C 2+ | 0.8％ |
| CO | 13.8％ |
| CO 2 | 4.5％ |
Example 3
In the embodiment, the hydrogen production reaction is carried out by taking the polyethylene plastic waste as a raw material, and the process flow is shown in fig. 1, and specifically comprises the following steps:
(1) crushing 100g of polyethylene plastic, putting the crushed polyethylene plastic into a microwave thermal cracking reactor (1), introducing nitrogen (50mL/min), setting the heating rate at 20 ℃/min, heating to 550 ℃ and keeping the temperature, and thermally cracking the polyethylene plastic to generate a thermal cracking product;
(2) loading 10g of catalyst (prepared by mixing 325-mesh iron oxide powder and carbon black powder according to the mass ratio of 4: 1) into a microwave catalytic dehydrogenation reactor (2), setting the microwave power to be 2000W and the frequency to be 2.45GHz, starting the microwave catalytic dehydrogenation reactor (2) while opening the microwave thermal cracking reactor (1), and preheating the loaded catalyst;
(3) introducing the thermal cracking product obtained in the step (1) into a microwave catalytic dehydrogenation reactor (2) through nitrogen gas as a carrier gas, carrying out microwave catalytic reaction for 30 minutes under the conditions of microwave power of 2000W and frequency of 2.45GHz to generate a hydrogen-containing gas product, carrying out gas washing, collecting, sampling and analyzing, wherein the result is shown in Table 3; the gas product is further processed by Pressure Swing Adsorption (PSA), the gas is collected, and the sample is taken for analysis, so that the purity of the hydrogen reaches 99.9 percent.
TABLE 3 gas product analysis results
| Composition (I) | Molar ratio of |
| H 2 | 74.2％ |
| CH 4 | 8.9％ |
| C 2+ | 3.6％ |
| CO | 10.2％ |
| CO 2 | 3.1％ |
Example 4
In the embodiment, the hydrogen production reaction is carried out by taking the polyethylene plastic waste as a raw material, and the process flow is shown in fig. 1, and specifically comprises the following steps:
(1) crushing 100g of polyethylene plastic, putting the crushed polyethylene plastic into a microwave thermal cracking reactor (1), introducing nitrogen (50mL/min), setting the heating rate at 20 ℃/min, heating to 500 ℃ and keeping the temperature, and thermally cracking the polyethylene plastic to generate a thermal cracking product;
(2) loading 10g of catalyst (prepared by mixing 325-mesh iron oxide powder and carbon black powder according to the mass ratio of 4: 1) into a microwave catalytic dehydrogenation reactor (2), setting the microwave power to be 3000W and the frequency to be 2.45GHz, starting the microwave catalytic dehydrogenation reactor (2) while opening the microwave thermal cracking reactor (1), and preheating the loaded catalyst;
(3) introducing the thermal cracking product obtained in the step (1) into a microwave catalytic dehydrogenation reactor (2) through carrier gas nitrogen, carrying out microwave catalytic reaction for 30 minutes under the conditions of microwave power of 3000W and frequency of 2.45GHz to generate a hydrogen-containing gas product, carrying out gas washing, collecting, sampling and analyzing, wherein the result is shown in Table 4; the gas product is further processed by Pressure Swing Adsorption (PSA), the gas is collected, and the sample is taken for analysis, so that the purity of the hydrogen reaches 99.9 percent.
TABLE 4 gas product analysis results
Example 5
In the embodiment, the hydrogen production reaction is performed by using polyethylene plastic waste as a raw material, and the process flow is shown in fig. 1, and specifically comprises the following steps:
(1) crushing 100g of polyethylene plastic, putting the crushed polyethylene plastic into a microwave thermal cracking reactor (1), introducing nitrogen (50mL/min), setting the heating rate at 20 ℃/min, heating to 550 ℃ and keeping the temperature, and thermally cracking the polyethylene plastic to generate a thermal cracking product;
(2) loading 10g of catalyst (the catalyst is a carbon black-supported metal iron catalyst, the mass ratio of metal iron to carbon black is 4: 1) into a microwave catalytic dehydrogenation reactor (2), setting the microwave power to be 2000W and the frequency to be 2.45GHz, starting the microwave catalytic dehydrogenation reactor (2) while opening the microwave thermal cracking reactor (1), and preheating the loaded catalyst;
(3) introducing the thermal cracking product obtained in the step (1) into a microwave catalytic dehydrogenation reactor (2) through carrier gas nitrogen, carrying out microwave catalytic reaction for 30 minutes under the conditions of microwave power of 2000W and frequency of 2.45GHz to generate a hydrogen-containing gas product, carrying out gas washing, collecting, sampling and analyzing, wherein the result is shown in Table 5; the gas product is further processed by Pressure Swing Adsorption (PSA), the gas is collected, and the sample is taken for analysis, so that the purity of the hydrogen reaches 99.9 percent.
TABLE 5 gas product analysis results
| Composition (I) | Molar ratio of |
| H 2 | 84.5％ |
| CH 4 | 6.8％ |
| C 2+ | 3.9％ |
| CO | 3.1％ |
| CO 2 | 1.7％ |
The catalyst in the embodiment is prepared by the following method: fully mixing carbon black and ferric nitrate in distilled water; calcining for 3 hours at 350 ℃ under the inert atmosphere of argon; after calcination was complete, at 5% H 2 And reducing the catalyst in an Ar environment at 650 ℃ for 6 hours. Finally collecting the black powder of the obtained carbon black-supported metallic iron catalyst, whichThe mass ratio of the medium iron to the carbon is 4: 1.
example 6
In the embodiment, the hydrogen production reaction is carried out by taking the polyethylene plastic waste as a raw material, and the process flow is shown in fig. 1, and specifically comprises the following steps:
(1) crushing 100g of polyethylene plastic, putting the crushed polyethylene plastic into a microwave thermal cracking reactor (1), introducing nitrogen (50mL/min), setting the heating rate at 20 ℃/min, heating to 550 ℃ and keeping the temperature, and thermally cracking the polyethylene plastic to generate a thermal cracking product;
(2) loading 10g of catalyst (the catalyst is a carbon black-supported metal iron catalyst, the mass ratio of metal iron to carbon black is 4: 1) into a microwave catalytic dehydrogenation reactor (2), setting the microwave power to be 1000W and the frequency to be 2.45GHz, starting the microwave catalytic dehydrogenation reactor (2) while opening the microwave thermal cracking reactor (1), and preheating the loaded catalyst;
(3) introducing the thermal cracking product obtained in the step (1) into a microwave catalytic dehydrogenation reactor (2) through carrier gas nitrogen, carrying out microwave catalytic reaction for 30 minutes under the conditions of microwave power of 1000W and frequency of 2.45GHz to generate a hydrogen-containing gas product, carrying out gas washing, collecting, sampling and analyzing, wherein the result is shown in Table 6; the gas product is further processed by Pressure Swing Adsorption (PSA), the gas is collected, and the sample is taken for analysis, so that the purity of the hydrogen reaches 99.9 percent.
TABLE 6 gas product analysis results
| Composition (I) | Molar ratio of |
| H 2 | 83％ |
| CH 4 | 7.8％ |
| C 2+ | 5.2％ |
| CO | 2.8％ |
| CO 2 | 1.2％ |
Example 7
In the embodiment, the hydrogen production reaction is carried out by taking the polyethylene plastic waste as a raw material, and the process flow is shown in fig. 1, and specifically comprises the following steps:
(1) crushing 100g of polyethylene plastic, putting the crushed polyethylene plastic into a microwave thermal cracking reactor (1), introducing nitrogen (50mL/min), setting the heating rate at 20 ℃/min, heating to 550 ℃ and keeping the temperature, and thermally cracking the polyethylene plastic to generate a thermal cracking product;
(2) loading 10g of catalyst (the catalyst is a carbon black-supported metal iron catalyst, the mass ratio of metal iron to carbon black is 4: 1) into a microwave catalytic dehydrogenation reactor (2), setting the microwave power to be 3000W and the frequency to be 2.45GHz, starting the microwave catalytic dehydrogenation reactor (2) while opening the microwave thermal cracking reactor (1), and preheating the loaded catalyst;
(3) introducing the thermal cracking product obtained in the step (1) into a microwave catalytic dehydrogenation reactor (2) through carrier gas nitrogen, carrying out microwave catalytic reaction for 30 minutes under the conditions of microwave power of 3000W and frequency of 2.45GHz to generate a hydrogen-containing gas product, carrying out gas washing, collecting, sampling and analyzing, wherein the result is shown in Table 7; the gas product is further processed by Pressure Swing Adsorption (PSA), the gas is collected, and the sample is taken for analysis, so that the purity of the hydrogen reaches 99.9 percent.
TABLE 7 analysis results of gas products
| Composition (I) | Molar ratio of |
| H 2 | 90.1％ |
| CH 4 | 3.4％ |
| C 2+ | 2.8％ |
| CO | 2.3％ |
| CO 2 | 1.4％ |
Example 8
In the embodiment, the hydrogen production reaction is carried out by taking the polyethylene plastic waste as a raw material, and the process flow is shown in fig. 1, and specifically comprises the following steps:
(1) crushing 150g of polyethylene plastic, putting the crushed polyethylene plastic into a microwave thermal cracking reactor (1), introducing nitrogen (50mL/min), setting the heating rate at 20 ℃/min, heating to 550 ℃ and keeping the temperature, and thermally cracking the polyethylene plastic to generate a thermal cracking product;
(2) taking 10g of catalyst (the catalyst is a carbon black loaded metal iron catalyst, the mass ratio of metal iron to carbon black is 4: 1) and loading the catalyst into a microwave catalytic dehydrogenation reactor (2), setting the microwave power to be 3000W and the frequency to be 2.45GHz, starting the microwave catalytic dehydrogenation reactor (2) while opening the microwave thermal cracking reactor (1), and preheating the loaded catalyst;
(3) introducing the thermal cracking product obtained in the step (1) into a microwave catalytic dehydrogenation reactor (2) through carrier gas nitrogen, carrying out microwave catalytic reaction for 30 minutes under the conditions of microwave power of 3000W and frequency of 2.45GHz to generate a hydrogen-containing gas product, carrying out gas washing, collecting, sampling and analyzing, wherein the result is shown in Table 8; the gas product is further processed by Pressure Swing Adsorption (PSA), the gas is collected, and the sample is taken for analysis, so that the purity of the hydrogen reaches 99.9 percent.
TABLE 8 gas product analysis results
| Composition (I) | Molar ratio of |
| H 2 | 88.7％ |
| CH 4 | 4.8％ |
| C 2+ | 3.1％ |
| CO | 2.7％ |
| CO 2 | 0.7％ |
Example 9
In the embodiment, the hydrogen production reaction is carried out by taking the polyethylene plastic waste as a raw material, and the process flow is shown in fig. 1, and specifically comprises the following steps:
(1) crushing 150g of polyethylene plastic, putting the crushed polyethylene plastic into a microwave thermal cracking reactor (1), introducing nitrogen (50mL/min), setting the heating rate at 20 ℃/min, heating to 550 ℃ and keeping the temperature, and thermally cracking the polyethylene plastic to generate a thermal cracking product;
(2) loading 10g of catalyst (the catalyst is a carbon black-supported metal iron catalyst, the mass ratio of metal iron to carbon black is 4: 1) into a microwave catalytic dehydrogenation reactor (2), setting the microwave power to be 4000W and the frequency to be 2.45GHz, starting the microwave catalytic dehydrogenation reactor (2) while opening the microwave thermal cracking reactor (1), and preheating the loaded catalyst;
(3) introducing the thermal cracking product obtained in the step (1) into a microwave catalytic dehydrogenation reactor (2) through carrier gas nitrogen, carrying out microwave catalytic reaction for 30 minutes under the conditions of microwave power 4000W and frequency 2.45GHz to generate a hydrogen-containing gas product, carrying out gas washing, collecting, sampling and analyzing, wherein the results are shown in Table 9; the gas product is further processed by Pressure Swing Adsorption (PSA), the gas is collected, and the sample is taken for analysis, so that the purity of the hydrogen reaches 99.9 percent.
TABLE 9 gas product analysis results
| Composition (A) | Molar ratio of |
| H 2 | 92.3％ |
| CH 4 | 3.2％ |
| C 2+ | 2.1％ |
| CO | 1.3％ |
| CO 2 | 1.1％ |
Example 10
In the embodiment, the hydrogen production reaction is performed by using polyethylene plastic waste as a raw material, and the process flow is shown in fig. 1, and specifically comprises the following steps:
(1) crushing 100g of polyethylene plastic, putting the crushed polyethylene plastic into a microwave thermal cracking reactor (1), introducing nitrogen (50mL/min), setting the heating rate at 20 ℃/min, heating to 550 ℃ and keeping the temperature, and thermally cracking the polyethylene plastic to generate a thermal cracking product;
(2) loading 10g of catalyst into a microwave catalytic dehydrogenation reactor (2), setting the microwave power to be 2000W and the frequency to be 2.45GHz, starting the microwave catalytic dehydrogenation reactor (2) while opening the microwave thermal cracking reactor (1), and preheating the loaded catalyst;
(3) and (2) introducing the thermal cracking product obtained in the step (1) into a microwave catalytic dehydrogenation reactor (2) through carrier gas nitrogen, carrying out microwave catalytic reaction for 30 minutes under the conditions of microwave power of 2000W and frequency of 2.45GHz to generate a hydrogen-containing gas product, carrying out gas washing, collecting, sampling and analyzing, and obtaining the results shown in Table 10.
In the step (2), the adopted catalyst is prepared by mixing 325-mesh iron oxide powder and carbon black powder, the influence of the catalyst in different proportions on the generation of a hydrogen-containing gas product is examined, and the mixing mass ratio of the iron oxide powder to the carbon black powder is respectively shown in the following table.
TABLE 10 gas product analysis results
| Composition (I) | 9:1 | 4:1 | 10:1 | 3:1 | 2:1 | 1:1 | 0.5:1 |
| H 2 | 76.6％ | 74.2％ | 71.9％ | 69.5％ | 68.2％ | 54.2％ | 47.7％ |
| CH 4 | 4.3％ | 8.9％ | 6.9％ | 8.1％ | 8.6％ | 17.9％ | 19.4％ |
| C 2+ | 0.8％ | 3.6％ | 6.1％ | 9.4％ | 9.9％ | 14.1％ | 24.8％ |
| CO | 13.8％ | 10.2％ | 12.4％ | 10.9％ | 11％ | 9.7％ | 5.4％ |
| CO 2 | 4.5％ | 3.1％ | 2.7％ | 2.1％ | 2.3％ | 4.1％ | 2.7％ |
As can be seen from a comparison of the data in table 10, the composition of the catalyst has a significant effect on the composition of the hydrogen-containing gaseous product produced. The mass ratio of the iron oxide powder to the carbon black powder in the catalyst is (4-10): 1, the content of hydrogen in the obtained gas product is more than 70 percent; as the amount of iron oxide powder in the iron oxide powder and carbon black powder mixture decreases, the hydrogen content of the resulting gaseous product decreases significantly.
Example 11
In the embodiment, the hydrogen production reaction is carried out by taking the polyethylene plastic waste as a raw material, and the process flow is shown in fig. 1, and specifically comprises the following steps:
(1) crushing 150g of polyethylene plastic, putting the crushed polyethylene plastic into a microwave thermal cracking reactor (1), introducing nitrogen (50mL/min), setting the heating rate at 20 ℃/min, heating to 550 ℃ and keeping the temperature, and thermally cracking the polyethylene plastic to generate a thermal cracking product;
(2) loading 10g of catalyst in a microwave catalytic dehydrogenation reactor (2), setting the microwave power to be 3000W and the frequency to be 2.45GHz, starting the microwave catalytic dehydrogenation reactor (2) while opening the microwave thermal cracking reactor (1), and preheating the loaded catalyst;
(3) and (2) introducing the thermal cracking product obtained in the step (1) into a microwave catalytic dehydrogenation reactor (2) through carrier gas nitrogen, carrying out microwave catalytic reaction for 30 minutes under the conditions of microwave power of 3000W and frequency of 2.45GHz to generate a hydrogen-containing gas product, carrying out gas washing, collecting, sampling and analyzing, and obtaining the results shown in Table 11.
In the step (2), the catalyst is a metal iron catalyst supported by carbon black, the influence of the catalyst in different proportions on the generation of the hydrogen-containing gas product is examined, and the mass ratio of the metal iron to the carbon black is shown in the following table.
TABLE 11 gas product analysis results
| Composition (I) | 4：1(Fe:C) | 0.5:1(Fe:C) | 1:1(Fe:C) | 2:1(Fe:C) | 3:1(Fe:C) | 5:1(Fe:C) |
| H 2 | 88.7％ | 77.6％ | 79.1％ | 80.6％ | 83.7％ | 85.3％ |
| CH 4 | 4.8％ | 11.1％ | 10.5％ | 7.5％ | 6.7％ | 5.2％ |
| C 2+ | 3.1％ | 9.2％ | 7.9％ | 6.6％ | 4.2％ | 4.5％ |
| CO | 2.7％ | 1.3％ | 1.6％ | 3.3％ | 3.5％ | 3.9％ |
| CO 2 | 0.7％ | 0.8％ | 0.9％ | 2％ | 1.9％ | 1.1％ |
As can be seen from a comparison of the data in table 11, the composition of the catalyst has a significant effect on the composition of the hydrogen-containing gaseous product produced. Compared with a mixed catalyst of iron oxide powder and carbon black powder, the effect of the metallic iron catalyst loaded by the carbon black is better. Particularly, the mass ratio of the metallic iron to the carbon black in the catalyst is (2-5): 1, the content of hydrogen in the obtained gas product is more than 80 percent; when the mass ratio of the metallic iron to the carbon black in the catalyst is 4: at 1, the maximum hydrogen content in the gas product was 88.7%.
The percentages in the above tables for the product gas analysis are all mole percentages.
Although the invention has been described in detail hereinabove by way of general description, specific embodiments and experiments, it will be apparent to those skilled in the art that many modifications and improvements can be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.
Claims (10)
1. The method for producing hydrogen by using polyethylene plastic is characterized in that the method takes the polyethylene plastic as a raw material to produce hydrogen, and comprises two continuous sections of treatment; wherein:
the first stage of treatment is microwave thermal cracking of polyethylene plastic to produce thermal cracking product;
the second stage treatment is that the thermal cracking product is subjected to microwave catalytic treatment to generate hydrogen-containing gas;
wherein, the catalyst adopted by the microwave catalytic treatment is selected from carbon materials, transition metal materials or transition metal materials taking carbon materials as carriers.
2. The method according to claim 1, wherein the transition metal material is an iron-based metal material, preferably selected from one or more of metallic iron, ferrous oxide, ferric oxide, ferroferric oxide, and iron carbide;
and/or the carbon material is carbon black, activated carbon or silicon carbide, preferably carbon black.
3. The method according to claim 1 or 2, wherein the catalyst is a mixture of a carbon material and the transition metal material or a transition metal material supported by a carbon material;
preferably, the catalyst comprises a transition metal material and a carbon material in a mass ratio of (1-99): 1, further preferably comprises a transition metal material and a carbon material in a mass ratio of (4-19): 1, and more preferably comprises a transition metal material and a carbon material in a mass ratio of (4-9): 1.
4. The method according to any one of claims 1 to 3, wherein the catalyst is a mixture of carbon black and iron oxide or carbon black supported metallic iron, preferably carbon black supported metallic iron.
5. A method according to any one of claims 1 to 4, wherein the temperature of the microwave thermal cracking is 450 to 800 ℃, preferably 500 to 750 ℃, more preferably 500 to 550 ℃.
6. The method according to any one of claims 1 to 5, wherein the power of the microwave catalytic treatment is 100 to 6000W, preferably 1000 to 4000W, more preferably 3000 to 4000W;
and/or the microwave frequency of the microwave thermal cracking and the microwave catalytic treatment is 2.45GHz or 915MHz, and is preferably 2.45 GHz.
7. The method according to any one of claims 1 to 6, wherein the microwave thermal cracking and the microwave catalytic treatment adopt a microwave thermal cracking reactor and a microwave catalytic dehydrogenation reactor which are connected in series; preferably, the catalyst in the microwave catalytic dehydrogenation reactor is preheated during microwave thermal cracking.
8. The method according to any one of claims 1 to 7, further comprising purifying the hydrogen-containing gas, preferably by a pressure swing adsorption process.
9. An apparatus for producing hydrogen, the apparatus comprising:
the microwave thermal cracking reactor is used for carrying out microwave thermal cracking treatment to generate a thermal cracking product;
the microwave catalytic dehydrogenation reactor is used for carrying out microwave treatment on the thermal cracking product in the presence of a catalyst to generate hydrogen-containing gas; and
a first gas collection tank for collecting the hydrogen-containing gas product;
preferably, a wave-absorbing material is arranged on the wall of the inner furnace of the microwave thermal cracking reactor; and/or the furnace body of the microwave catalytic dehydrogenation reactor is made of quartz or stainless steel.
10. The apparatus of claim 9, further comprising:
the pressure swing adsorption unit is used for carrying out pressure swing adsorption purification on the hydrogen-containing gas to generate high-purity hydrogen; and
and the second gas collecting tank is used for collecting the high-purity hydrogen.
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| CN114621779A (en) * | 2022-03-22 | 2022-06-14 | 苏州大学 | Method for microwave catalytic cracking of polyolefin waste plastic and production of hydrogen and carbon nanofibers |
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| CN112238122A (en) * | 2020-09-15 | 2021-01-19 | 介翔宇 | Treatment process for microwave catalytic decomposition of medical waste |
| CN112624041A (en) * | 2021-01-19 | 2021-04-09 | 宋金文 | Method for producing hydrogen by using waste biomass carbon |
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| CN115869952A (en) * | 2023-02-22 | 2023-03-31 | 广东以色列理工学院 | Catalyst for plastic degradation hydrogen production and preparation method and application thereof |
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