Method for preparing aliphatic hydrocarbon through co-pyrolysis of waste ethylene-vinyl acetate copolymer and waste polyolefin elastomer

Abstract

The invention discloses a method for preparing aliphatic hydrocarbon through co-pyrolysis of a photovoltaic module laminated part waste ethylene-vinyl acetate copolymer and a waste polyolefin elastomer. Physical and chemical complementation and free radical synergy of the ethylene-vinyl acetate copolymer and the polyolefin elastomer in the pyrolysis process are utilized; compared with independent pyrolysis, hydrogen transfer and deoxidation in co-pyrolysis have a synergistic effect, so that the selectivity and yield of aliphatic hydrocarbon are improved, generation of acidic oxygen-containing components and aromatics caused by deacetic acid is remarkably reduced, a liquid product is mainly composed of aliphatic hydrocarbon, carbon chain distribution is directionally concentrated to a short chain range, and meanwhile, tail gas corrosivity and post-treatment load are reduced. The solid carbon generated in the reaction process has a certain microporous structure and can be used as an adsorbent, an electrode material or a carbon-based fertilizer carrier, so that clean treatment and resource utilization of organic components of the retired photovoltaic module are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of comprehensive utilization of solid waste, and particularly relates to a method for preparing aliphatic hydrocarbons by co-pyrolysis of waste ethylene-vinyl acetate copolymer and waste polyolefin elastomer of photovoltaic module laminates. BACKGROUND

[0002] A typical crystalline silicon photovoltaic module is formed by vacuum lamination of multiple layers of materials such as tempered glass, encapsulant film, photovoltaic cell, backsheet or second glass, wherein the mass proportion of glass is about 70% to 75%, and the mass proportion of encapsulant film is about 8% to 12%. The encapsulant film is mainly composed of ethylene-vinyl acetate copolymer and polyolefin elastomer, and contains peroxide crosslinking agent, silane coupling agent, antioxidant and ultraviolet absorber. After lamination, a highly cross-linked and dense network structure is formed, which is difficult to dissolve and melt for reprocessing. Existing disposal methods focus on recycling glass and metal, and the encapsulant film is often stripped and then landfilled or incinerated, which not only wastes carbon-hydrogen resources, but also releases acidic volatile substances such as acetic acid and increases the load of tail gas treatment. Pyrolysis technology can crack high molecular into gaseous, liquid and solid products under oxygen-free conditions, but ethylene-vinyl acetate copolymer alone is prone to de-acetate and carbonization, resulting in increased acidity and reduced calorific value of the product, which is not conducive to storage, transportation and direct use. Although polyolefin elastomer alone is mainly aliphatic hydrocarbon, the carbon number distribution is wide and the light and heavy are not balanced, making it difficult to obtain target products directly. Considering that the two types of encapsulant films often coexist or are co-extruded in actual retired laminates, the front-end sorting is difficult and costly. SUMMARY

[0003] The purpose of the present application is to provide a method for preparing aliphatic hydrocarbons by co-pyrolysis of waste ethylene-vinyl acetate copolymer and waste polyolefin elastomer of photovoltaic module laminates, which solves the problem of high sorting difficulty and low calorific value of the product in the prior art.

[0004] The present application is realized by the following technical solutions:

[0005] The method for preparing aliphatic hydrocarbons by co-pyrolysis of waste ethylene-vinyl acetate copolymer and waste polyolefin elastomer of photovoltaic module laminates comprises the following steps: waste ethylene-vinyl acetate copolymer and waste polyolefin elastomer of photovoltaic module laminates are mixed at a mass ratio of 1:0.2 to 5, and co-pyrolysis is carried out at an argon, nitrogen or helium atmosphere and a temperature of 450 to 750 DEG C, with a heating rate of 10 to 10 4 ℃ / s and a holding time of 5 to 60 s, to obtain a pyrolysis product mainly composed of aliphatic hydrocarbons.

[0006] Preferably, the pyrolysis product is mainly composed of short-chain aliphatic hydrocarbons, and contains a certain proportion of medium-chain aliphatic hydrocarbons and long-chain aliphatic hydrocarbons, and has a low content of acids and aromatic compounds.

[0007] The short-chain aliphatic hydrocarbons refer to straight-chain or branched-chain alkanes, alkenes and cycloalkanes with a carbon number of not more than 10. The medium-chain aliphatic hydrocarbons refer to aliphatic hydrocarbons with a carbon number of 11-20, and the long-chain aliphatic hydrocarbons refer to aliphatic hydrocarbons with a carbon number of more than 20.

[0008] Preferably, the ethylene-vinyl acetate copolymer and the polyolefin elastomer are taken from a scrapped photovoltaic module laminate with a particle size of 60-240 mesh.

[0009] Preferably, the mass ratio of the waste ethylene-vinyl acetate copolymer to the waste polyolefin elastomer is 1:1-5.

[0010] Preferably, the temperature of the co-pyrolysis is 650-750 DEG C, and the holding time is 20 s.

[0011] The ethylene-vinyl acetate copolymer and the polyolefin elastomer in the present application are complementary in physicochemical properties and synergistic in free radicals during pyrolysis, realizing the directional conversion and synergistic disposal of the organic components of the retired photovoltaic module. The ethylene-vinyl acetate copolymer is first subjected to de-acetic acid reaction to generate acidic oxygen-containing intermediates and unsaturated polyolefin fragments under heating, which are prone to condensation carbonization and aromatization when pyrolyzed alone, resulting in a decrease in the quality of the oil product and the generation of corrosive gases. The polyolefin elastomer has a very low oxygen content and a high hydrogen-carbon ratio, and the cracking produces hydrogen-rich hydrocarbon fragments and active hydrogen radicals. Under the condition of co-pyrolysis, the two types of materials undergo synergistic reactions such as hydrogen transfer, hydrogenation cracking and deoxygenation decarboxylation, which can quickly passivate the unsaturated intermediates, inhibit the condensation and aromatization channels, significantly reduce the proportion of acidic oxygen-containing components and aromatic compounds, make the liquid product mainly composed of aliphatic hydrocarbons, and direct the carbon chain distribution to the short-chain range. Due to the complementarity of the two types of raw materials in thermal behavior, hydrogen donor ability and reaction path, the co-pyrolysis has a higher liquid yield and a more optimal carbon chain distribution than the pyrolysis of a single raw material, and can be controlled and adjusted between short-chain, medium-chain and long-chain according to needs, while reducing the corrosiveness of tail gas and the load of post-processing. The solid carbon generated in the reaction process has a certain microporous structure, which can be used as an adsorbent, an electrode material or a carbon-based fertilizer carrier. Therefore, the present application utilizes the complementary characteristics of ethylene-vinyl acetate copolymer and polyolefin elastomer in physics and chemistry, and adopts pyrolysis to synergistically dispose the two types of materials derived from photovoltaic module laminates, which not only prepares liquid products mainly composed of aliphatic hydrocarbons, but also realizes the harmless and resourceful disposal of the organic components of the retired photovoltaic module.

[0012] The beneficial effects of the present application are as follows:

[0013] 1) The present application utilizes the physicochemical complementarity and radical synergy of ethylene-vinyl acetate copolymer and polyolefin elastomer in the pyrolysis process, the hydrogen transfer and deoxygenation synergy in co-pyrolysis, compared with single pyrolysis, to improve the selectivity and yield of aliphatic hydrocarbons, significantly reduce the generation of acidic oxygen-containing components and aromatics caused by deacetic acid, make the liquid product mainly aliphatic hydrocarbons, and direct the carbon chain distribution to the short chain range, while reducing the corrosion of tail gas and the load of post-treatment. The solid carbon generated in the reaction process has a certain microporous structure, which can be used as an adsorbent, electrode material or carbon-based fertilizer carrier for utilization, realizing the clean disposal and resource utilization of the organic components of the retired photovoltaic module.

[0014] 2) The present application can obtain aliphatic hydrocarbon liquid mainly composed of short chains, while considering the retention and inhibition of medium and long chains, reducing secondary condensation and coking, and reducing the tail gas treatment and equipment corrosion pressure.

[0015] 3) The method of the present application is simple to operate and does not require additional investment, and can be further applied to the resource utilization of other carbon-containing high molecular solid waste. DETAILED DESCRIPTION

[0016] The following is a further description of the present application, but not a limitation of the present application.

[0017] Example 1:

[0018] 120 mesh waste ethylene-vinyl acetate copolymer and waste polyolefin elastomer were uniformly mixed in a mass ratio of 1:1, and co-pyrolysis was carried out at a heating rate of 10 4 ℃ / s, pyrolysis temperature 650 ℃, pyrolysis atmosphere argon for 20 s; the relative content of various chemicals in the pyrolysis products was analyzed by gas chromatography-mass spectrometry, and the relative content of short chain aliphatic hydrocarbons in the pyrolysis products was calculated to be 60.8%, the relative content of medium chain aliphatic hydrocarbons was 29.3%, the relative content of long chain aliphatic hydrocarbons was 8.7%, the relative content of acid was 0%, the relative content of aromatic compounds was 1.2%, and the total amount of aliphatic hydrocarbons was 98.6%. See Table 1.

[0019] Table 1

[0020] Comparative Example 1:

[0021] The same as example 1, except that the raw material is only waste ethylene-vinyl acetate copolymer. By gas chromatography-mass spectrometry analysis of the relative content of various chemicals in the pyrolysis products, the relative content of short-chain aliphatic hydrocarbons in the pyrolysis products is calculated to be 32.8%, the relative content of medium-chain aliphatic hydrocarbons is 29.1%, the relative content of long-chain aliphatic hydrocarbons is 22.4%, the relative content of acids is 12.8%, the relative content of aromatic compounds is 2.3%, and the total amount of aliphatic hydrocarbons is 84.3%.

[0022] Comparative example 2:

[0023] The same as example 1, except that the raw material is only waste ethylene-vinyl acetate copolymer. By gas chromatography-mass spectrometry analysis of the relative content of various chemicals in the pyrolysis products, the relative content of short-chain aliphatic hydrocarbons in the pyrolysis products is calculated to be 32.8%, the relative content of medium-chain aliphatic hydrocarbons is 29.1%, the relative content of long-chain aliphatic hydrocarbons is 22.4%, the relative content of acids is 12.8%, the relative content of aromatic compounds is 2.3%, and the total amount of aliphatic hydrocarbons is 84.3%.

[0024] From example 1, comparative example 1 and comparative example 2, it can be seen that the pyrolysis of ethylene-vinyl acetate copolymer or polyolefin elastomer alone is difficult to obtain pyrolysis oil mainly composed of short-chain aliphatic hydrocarbons, and the acid content and aromatic compound content are high; while the co-pyrolysis of the two can significantly increase the total amount of aliphatic hydrocarbons, direct the carbon chain distribution to short-chain, and reduce the acid content and aromatic compound content.

[0025] Example 2:

[0026] 120 mesh waste ethylene-vinyl acetate copolymer and waste polyolefin elastomer are uniformly mixed in a mass ratio of 1:1, and co-pyrolysis is carried out at a pyrolysis temperature of 750 ℃, a heating rate of 10 4 ℃ / s, and an argon atmosphere for 20 s; by gas chromatography-mass spectrometry analysis of the relative content of various chemicals in the pyrolysis products, the relative content of short-chain aliphatic hydrocarbons in the pyrolysis products is calculated to be 63.6%, the relative content of medium-chain aliphatic hydrocarbons is 26.9%, the relative content of long-chain aliphatic hydrocarbons is 7.5%, the relative content of acids is 0.2%, the relative content of aromatic compounds is 1.5%, and the total amount of aliphatic hydrocarbons is 98.0%.

[0027] Example 3

[0028] 120 mesh waste ethylene-vinyl acetate copolymer and waste polyolefin elastomer are uniformly mixed in a mass ratio of 1:1, and co-pyrolysis is carried out at a pyrolysis temperature of 550 ℃, a heating rate of 10 4Co-pyrolysis was carried out at ℃ / s under helium atmosphere for 20 s. The relative contents of various chemicals in the pyrolysis products were analyzed by gas chromatography-mass spectrometry. The relative contents of short-chain aliphatic hydrocarbons were calculated to be 41.9%, medium-chain aliphatic hydrocarbons were 34.1%, long-chain aliphatic hydrocarbons were 21.5%, acids were 1.1%, aromatic compounds were 1.0%, and the total aliphatic hydrocarbons were 97.5%.

[0029] Example 4

[0030] Waste ethylene-vinyl acetate copolymer (60 mesh) and waste polyolefin elastomer were uniformly mixed at a mass ratio of 1:1, and then subjected to pyrolysis at a temperature of 450 °C and a heating rate of 10 °C. 4 Co-pyrolysis was carried out at ℃ / s under a nitrogen atmosphere for 20 s. The relative contents of various chemicals in the pyrolysis products were analyzed by gas chromatography-mass spectrometry. The relative contents of short-chain aliphatic hydrocarbons were calculated to be 36.5%, medium-chain aliphatic hydrocarbons 33.4%, long-chain aliphatic hydrocarbons 26.2%, acids 2.1%, aromatic compounds 0.8%, and the total aliphatic hydrocarbons 96.1%.

[0031] Example 5

[0032] 120-mesh waste ethylene-vinyl acetate copolymer and waste polyolefin elastomer were uniformly mixed at a mass ratio of 1:3, and the mixture was subjected to pyrolysis at a temperature of 550 ℃ and a heating rate of 10 °C. 3 Co-pyrolysis was carried out at ℃ / s under helium atmosphere for 20 s. The relative contents of various chemicals in the pyrolysis products were analyzed by gas chromatography-mass spectrometry. The relative contents of short-chain aliphatic hydrocarbons were calculated to be 52.5%, medium-chain aliphatic hydrocarbons 29.1%, long-chain aliphatic hydrocarbons 15.6%, acids 1.1%, aromatic compounds 1.5%, and the total aliphatic hydrocarbons 97.2%.

[0033] Example 6

[0034] 120-mesh waste ethylene-vinyl acetate copolymer and waste polyolefin elastomer were uniformly mixed at a mass ratio of 1:0.3, and the mixture was subjected to pyrolysis at a temperature of 550 °C and a heating rate of 10 °C. 4Co-pyrolysis was carried out at ℃ / s under an argon atmosphere for 20 s. The relative contents of various chemicals in the pyrolysis products were analyzed by gas chromatography-mass spectrometry. The relative contents of short-chain aliphatic hydrocarbons were calculated to be 31.5%, medium-chain aliphatic hydrocarbons 26.2%, long-chain aliphatic hydrocarbons 38.2%, acids 2.9%, aromatic compounds 0.9%, and the total aliphatic hydrocarbons 95.9%.

[0035] Example 7

[0036] 240-mesh waste ethylene-vinyl acetate copolymer and waste polyolefin elastomer were uniformly mixed at a mass ratio of 1:1, and the mixture was subjected to pyrolysis at a temperature of 450 ℃ and a heating rate of 10 °C. 4 Co-pyrolysis was carried out at ℃ / s under helium atmosphere for 20 s. The relative contents of various chemicals in the pyrolysis products were analyzed by gas chromatography-mass spectrometry. The relative contents of short-chain aliphatic hydrocarbons were calculated to be 34.2%, medium-chain aliphatic hydrocarbons 34.7%, long-chain aliphatic hydrocarbons 26.7%, acids 1.9%, aromatic compounds 1.1%, and the total aliphatic hydrocarbons 95.6%.

[0037] Example 8

[0038] 240-mesh waste ethylene-vinyl acetate copolymer and waste polyolefin elastomer were uniformly mixed at a mass ratio of 1:3, and the mixture was subjected to pyrolysis at a temperature of 750 °C and a heating rate of 10 °C. 3 Co-pyrolysis was carried out at ℃ / s under an argon atmosphere for 20 s. The relative contents of various chemicals in the pyrolysis products were analyzed by gas chromatography-mass spectrometry. The relative contents of short-chain aliphatic hydrocarbons were calculated to be 65.6%, medium-chain aliphatic hydrocarbons 24.5%, long-chain aliphatic hydrocarbons 7.1%, acids 0.2%, aromatic compounds 2.3%, and the total aliphatic hydrocarbons 97.2%.

[0039] Example 9

[0040] 120-mesh waste ethylene-vinyl acetate copolymer and waste polyolefin elastomer were uniformly mixed at a mass ratio of 1:5, and the mixture was subjected to pyrolysis at a temperature of 650 ℃ and a heating rate of 10 °C. 4Co-pyrolysis was carried out at ℃ / s under a nitrogen atmosphere for 20 s. The relative contents of various chemicals in the pyrolysis products were analyzed by gas chromatography-mass spectrometry. The relative contents of short-chain aliphatic hydrocarbons were calculated to be 64.2%, medium-chain aliphatic hydrocarbons were 24.3%, long-chain aliphatic hydrocarbons were 7.3%, acids were 0%, aromatic compounds were 3.9%, and the total aliphatic hydrocarbons were 95.8%.

[0041] Example 10

[0042] 60-mesh waste ethylene-vinyl acetate copolymer and waste polyolefin elastomer were uniformly mixed at a mass ratio of 1:1, and the mixture was subjected to pyrolysis at a temperature of 550 ℃ and a heating rate of 10 °C. Co-pyrolysis was carried out at ℃ / s under an argon atmosphere for 20 s. The relative contents of various chemicals in the pyrolysis products were analyzed by gas chromatography-mass spectrometry. The relative contents of short-chain aliphatic hydrocarbons were calculated to be 38.2%, medium-chain aliphatic hydrocarbons 31.2%, long-chain aliphatic hydrocarbons 26.7%, acids 1.2%, aromatic compounds 1.1%, and the total aliphatic hydrocarbons 96.1%.

[0043] Example 11

[0044] 120-mesh waste ethylene-vinyl acetate copolymer and waste polyolefin elastomer were uniformly mixed at a mass ratio of 1:0.2, and the mixture was subjected to pyrolysis at a temperature of 650 °C and a heating rate of 10 °C. 4 Co-pyrolysis was carried out at ℃ / s under helium atmosphere for 20 s. The relative contents of various chemicals in the pyrolysis products were analyzed by gas chromatography-mass spectrometry. The relative contents of short-chain aliphatic hydrocarbons were calculated to be 27.9%, medium-chain aliphatic hydrocarbons were 24.6%, long-chain aliphatic hydrocarbons were 42.8%, acids were 3.7%, aromatic compounds were 0.6%, and the total aliphatic hydrocarbons were 95.3%.

[0045] Example 12

[0046] 240-mesh waste ethylene-vinyl acetate copolymer and waste polyolefin elastomer were uniformly mixed at a mass ratio of 1:1, and the mixture was subjected to pyrolysis at a temperature of 550 °C and a heating rate of 10 °C. 4Co-pyrolysis was carried out at ℃ / s under a nitrogen atmosphere for 20 s. The relative contents of various chemicals in the pyrolysis products were analyzed by gas chromatography-mass spectrometry. The relative contents of short-chain aliphatic hydrocarbons were calculated to be 39.7%, medium-chain aliphatic hydrocarbons were 36.0%, long-chain aliphatic hydrocarbons were 21.4%, acids were 1.2%, aromatic compounds were 0.9%, and the total aliphatic hydrocarbons were 97.1%.

[0047] Example 13

[0048] 60-mesh waste ethylene-vinyl acetate copolymer and waste polyolefin elastomer were uniformly mixed at a mass ratio of 1:5, and the mixture was subjected to pyrolysis at a temperature of 750 ℃ ​​and a heating rate of 10. Co-pyrolysis was carried out at ℃ / s under an argon atmosphere for 20 s. The relative contents of various chemicals in the pyrolysis products were analyzed by gas chromatography-mass spectrometry. The relative contents of short-chain aliphatic hydrocarbons were calculated to be 68.0%, medium-chain aliphatic hydrocarbons were 21.4%, long-chain aliphatic hydrocarbons were 6.1%, acids were 0%, aromatic compounds were 4.0%, and the total aliphatic hydrocarbons were 95.5%.

[0049] Example 14

[0050] 120-mesh waste ethylene-vinyl acetate copolymer and waste polyolefin elastomer were uniformly mixed at a mass ratio of 1:1, and the mixture was subjected to pyrolysis at a temperature of 450 ℃ and a heating rate of 10 °C. 3 Co-pyrolysis was carried out at ℃ / s under a nitrogen atmosphere for 20 s. The relative contents of various chemicals in the pyrolysis products were analyzed by gas chromatography-mass spectrometry. The relative contents of short-chain aliphatic hydrocarbons were calculated to be 32.9%, medium-chain aliphatic hydrocarbons were 33.7%, long-chain aliphatic hydrocarbons were 29.0%, acids were 2.3%, aromatic compounds were 0.9%, and the total aliphatic hydrocarbons were 95.6%.

Claims

1. Process for the preparation of aliphatic hydrocarbons by co-pyrolysis of waste ethylene-vinyl acetate copolymer and waste polyolefin elastomer from photovoltaic module laminates, characterized in that, The method comprises the following steps: mixing photovoltaic module laminate waste ethylene-vinyl acetate copolymer and waste polyolefin elastomer at a mass ratio of 1:0.2-5, and performing co-pyrolysis at 450-750 DEG C under an argon, nitrogen or helium atmosphere, with a temperature rising rate of 10-10 4 ℃ / s, and a co-pyrolysis holding time of 5-60 s, to obtain a pyrolysis product mainly composed of aliphatic hydrocarbons.

2. The method of claim 1, wherein, The pyrolysis product mainly contains short-chain aliphatic hydrocarbons, and also contains a certain proportion of medium-chain aliphatic hydrocarbons and long-chain aliphatic hydrocarbons.

3. The method of claim 2, wherein, The short-chain aliphatic hydrocarbons refer to straight-chain or branched-chain alkanes, alkenes and cycloalkanes with carbon number not greater than 10, the medium-chain aliphatic hydrocarbons refer to aliphatic hydrocarbons with carbon number of 11-20, and the long-chain aliphatic hydrocarbons refer to aliphatic hydrocarbons with carbon number greater than 20.

4. The method of claim 1, wherein, The ethylene-vinyl acetate copolymer and the polyolefin elastomer are taken from a scrapped photovoltaic module laminate, and the particle size is 60-240 mesh.

5. The method of claim 1, wherein, The mass ratio of the waste ethylene-vinyl acetate copolymer and the waste polyolefin elastomer is 1:1-5.

6. The method of claim 1, wherein, The temperature of the co-pyrolysis is 650-750 DEG C, and the holding time is 20 s.

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