METHOD AND DEVICE SYSTEM FOR PRODUCING FEED STOCK OF ETHYLENE STEAM CRACKER AND NANO-CARBON MATERIAL FROM WASTE PLASTICS
20250115812 ยท 2025-04-10
Inventors
Cpc classification
C10G1/002
CHEMISTRY; METALLURGY
C10G5/00
CHEMISTRY; METALLURGY
International classification
C10G1/00
CHEMISTRY; METALLURGY
C10G65/12
CHEMISTRY; METALLURGY
Abstract
The present application relates to a method and a device system for producing feed stock of ethylene steam cracker and a nano-carbon material from waste plastics, and the method comprises: firstly, subjecting a waste plastic to thermal pyrolysis to obtain hydrocarbon oil and gas from thermal pyrolysis; then, subjecting the hydrocarbon oil and gas from thermal pyrolysis to gas-liquid separation to obtain crude plastic pyrolysis oil and pyrolysis gas; subsequently, subjecting the pyrolysis gas to decarbonization to obtain a nano-carbon material, and sequentially subjecting the crude plastic pyrolysis oil to hydrocracking and fractionating to obtain the feed stock of ethylene steam cracker. The device system comprises a thermal pyrolysis unit, a gas-liquid separation unit, a hydrocracking unit, a fractionating unit, and a decarbonization unit. The method and device system provided in the present application can prepare the steam-cracking feedstock of ethylene steam cracker with a high proportion of chain alkanes, which can achieve a higher yield of target products when used to produce downstream products, and the production process has no carbon dioxide emission, and is green and clean. The device system provided in the present application has a simple structure and can be used in industrial application.
Claims
1-13. (canceled)
14. A method for producing feed stock of ethylene steam cracker and a nano-carbon material from waste plastics, comprising the following steps: (1) subjecting a waste plastic to thermal pyrolysis to obtain hydrocarbon oil and gas from thermal pyrolysis; (2) subjecting the hydrocarbon oil and gas from thermal pyrolysis obtained in step (1) to gas-liquid separation to obtain crude plastic pyrolysis oil and pyrolysis gas; (3) subjecting the pyrolysis gas obtained in step (2) to decarbonization to obtain the nano-carbon material and hydrogen, and subjecting the hydrogen to purification and then using in hydrocracking in step (4); (4) subjecting the crude plastic pyrolysis oil obtained in step (2) to hydrocracking to obtain hydrotreated plastic pyrolysis oil; and (5) fractionating the hydrotreated plastic pyrolysis oil obtained in step (4) to obtain the feed stock of ethylene steam cracker; the decarbonization in step (3) adopts a high-temperature thermal pyrolysis technology; the decarbonization is performed at a temperature of 1500-3500 C.; the decarbonization is performed at a pressure of 0.5-5 MPa; a heavy component and mixed hydrocarbon gas are also obtained after the fractionating in step (5); the heavy component is used back for the hydrocracking in step (4); the mixed hydrocarbon gas is used back for the decarbonization in step (3).
15. The method according to claim 14, wherein the waste plastic in step (1) comprises polyethylene and/or polypropylene.
16. The method according to claim 14, wherein the waste plastic is subjected to a pretreatment before the thermal pyrolysis.
17. The method according to claim 16, wherein a method of the pretreatment comprises any one or a combination of at least two of magnetic separation, infrared separation, or density separation.
18. The method according to claim 14, wherein the thermal pyrolysis is performed at a temperature of 400-550 C.
19. The method according to claim 14, wherein the pyrolysis gas in step (2) comprises hydrogen and non-condensable hydrocarbon gas.
20. The method according to claim 19, wherein the non-condensable hydrocarbon gas comprises C1-C4 gaseous hydrocarbon.
21. The method according to claim 14, wherein the purification comprises pressure swing adsorption or membrane separation.
22. The method according to claim 14, wherein the hydrocracking in step (4) is performed at a temperature of 300-400 C.
23. The method according to claim 14, wherein the hydrocracking is performed at a pressure of 3-15 MPa.
24. The method according to claim 14, wherein a fraction range of the heavy component is 350-550 C.
25. The method according to claim 14, wherein the mixed hydrocarbon gas comprises C1-C4 gaseous hydrocarbon.
26. The method according to claim 14, wherein a fraction range of the feed stock of ethylene steam cracker is 65-400 C.
27. The method according to claim 14, comprising the following steps: (1) subjecting a waste plastic to a pretreatment, where a method of the pretreatment comprises any one or a combination of at least two of magnetic separation, infrared separation, or density separation, and then performing thermal pyrolysis at a temperature of 400-550 C. to obtain hydrocarbon oil and gas from thermal pyrolysis; (2) subjecting the hydrocarbon oil and gas from thermal pyrolysis obtained in step (1) to gas-liquid separation to obtain crude plastic pyrolysis oil and pyrolysis gas; (3) subjecting the pyrolysis gas obtained in step (2) to decarbonization by a high-temperature thermal pyrolysis technology at a temperature of 1500-3500 C. and a pressure of 0.5-5 MPa to obtain the nano-carbon material and hydrogen, and subjecting the hydrogen to pressure swing adsorption or membrane separation and then using in hydrocracking in step (4); (4) subjecting the crude plastic pyrolysis oil obtained in step (2) to hydrocracking at a temperature of 300-400 C. and a pressure of 3-15 MPa to obtain hydrotreated plastic pyrolysis oil; and (5) fractionating the hydrotreated plastic pyrolysis oil obtained in step (4) to obtain the feed stock of ethylene steam cracker, a heavy component, and mixed hydrocarbon gas, where a fraction range of the feed stock of ethylene steam cracker is 65-400 C., a fraction range of the heavy component is 350-550 C., the mixed hydrocarbon gas comprises C1-C4 gaseous hydrocarbon, the heavy component is used back for the hydrocracking in step (4), and the mixed hydrocarbon gas is used back for the decarbonization in step (3).
28. A device system for producing feed stock of ethylene steam cracker and a nano-carbon material from waste plastics, which is used for the method for producing feed stock of ethylene steam cracker and a nano-carbon material from waste plastics according to claim 14; the device system comprises a thermal pyrolysis unit, a gas-liquid separation unit, a hydrocracking unit, and a fractionating unit which are connected in sequence; an outlet of the thermal pyrolysis unit is connected to an inlet of the gas-liquid separation unit; a liquid-phase outlet of the gas-liquid separation unit is connected to an inlet of the hydrocracking unit; an outlet of the hydrocracking unit is connected to an inlet of the fractionating unit; a gas-phase outlet of the gas-liquid separation unit is connected to an inlet of a decarbonization unit.
29. The device system according to claim 28, wherein the device system further comprises a pretreatment unit; an outlet of the pretreatment unit is connected to an inlet of the thermal pyrolysis unit.
30. The device system according to claim 28, wherein a gas-phase outlet of the decarbonization unit is connected to the inlet of the hydrocracking unit.
31. The device system according to claim 28, wherein a gas-phase outlet of the fractionating unit is connected to the inlet of the decarbonization unit.
32. The device system according to claim 28, wherein a heavy-component outlet of the fractionating unit is connected to the inlet of the hydrocracking unit.
Description
BRIEF DESCRIPTION OF DRAWINGS
[0074] Accompanying drawings are used to provide a further understanding of the technical solutions herein, form part of the specification, explain the technical solutions together with examples of the present application, and do not limit the technical solutions herein.
[0075]
[0076] reference list: 100pretreatment unit; 200thermal pyrolysis unit; 300gas-liquid separation unit; 400hydrocracking unit; 500fractionating unit; and 600decarbonization unit.
DETAILED DESCRIPTION
[0077] The technical solutions of the present application are further described below in terms of embodiments. It should be understood by those skilled in the art that the example are merely intended for assist in the understanding of the present application and should not be regarded as specific limitations of the present application.
[0078] In one embodiment, the method for producing feed stock of ethylene steam cracker and a nano-carbon material from waste plastics provided in the present application is performed in a device system for producing feed stock of ethylene steam cracker and a nano-carbon material from waste plastics, and the structural schematic diagram of the device system is shown in
[0079] The device system further comprises a pretreatment unit 100: an outlet of the pretreatment unit 100 is connected to an inlet of the thermal pyrolysis unit 200: impurities in waste plastics can be further removed by providing the pretreatment unit 100.
[0080] A gas-phase outlet of the decarbonization unit 600 is connected to an inlet of the hydrocracking unit 400, whereby the hydrogen obtained by the decarbonization can be subjected to hydrocracking and improved in utilization rate.
[0081] A gas-phase outlet of the fractionating unit 500 is connected to an inlet of the decarbonization unit 600, and a heavy-component outlet of the fractionating unit 500 is connected to an inlet of the hydrocracking unit 400, so that the circulation of the mixed hydrocarbon gas and the heavy component can be realized, and the yield of the feed stock of ethylene steam cracker can be further improved.
Example 1
[0082] This example provides a method for producing feed stock of ethylene steam cracker and a nano-carbon material from waste plastics, the structural schematic diagram of the device system used therein is shown in
Example 2
[0088] This example provides a method for producing feed stock of ethylene steam cracker and a nano-carbon material from waste plastics, the device system used therein is the same as in Example 1, and the method comprises the following steps: [0089] (1) the polypropylene waste plastic was pretreated in the pretreatment unit 100, and in the pretreatment, magnetic separation was first used to remove impurities such as metal, stone, and sand, and then density separation was used to remove the plastic not made of polypropylene, then thermal pyrolysis was performed at 400 C. in the thermal pyrolysis unit 200 to obtain hydrocarbon oil and gas from thermal pyrolysis, and also ash was generated; [0090] (2) the hydrocarbon oil and gas from thermal pyrolysis obtained in step (1) was sent to the gas-liquid separation unit 300 for gas-liquid separation to obtain crude plastic pyrolysis oil and pyrolysis gas; [0091] (3) the pyrolysis gas obtained in step (2) was introduced to the decarbonization unit 600, and decarbonization was performed at a temperature of 1500 C. and a pressure of 1.5 MPa by a high-temperature thermal pyrolysis technology to obtain a nano-carbon material and hydrogen, and the hydrogen was subjected to membrane separation, thus having a purity of 99.99%, and then used in step (4); [0092] (4) the crude plastic pyrolysis oil obtained in step (2) was sent to the hydrocracking unit 400 for hydrocracking at a temperature of 400 C. and a pressure of 3 MPa to obtain hydrotreated plastic pyrolysis oil; and [0093] (5) the hydrotreated plastic pyrolysis oil obtained in step (4) was sent to the fractionating unit 500 for fractionating to obtain the feed stock of ethylene steam cracker, a heavy component, and mixed hydrocarbon gas, where a fraction range of the feed stock of ethylene steam cracker was 65-400 C., a fraction range of the heavy component was 350-550 C., and the mixed hydrocarbon gas was C1-C4 gaseous hydrocarbon: the heavy component was returned to the hydrocracking unit 400 for use in the hydrocracking in step (4), and the mixed hydrocarbon gas was returned to the decarbonization unit 600 for use in the decarbonization in step (3).
Example 3
[0094] This example provides a method for producing feed stock of ethylene steam cracker and a nano-carbon material from waste plastics, the device system used therein is the same as in Example 1, and the method comprises the following steps: [0095] (1) the polypropylene waste plastic and polyethylene waste plastic were pretreated in the pretreatment unit 100, and in the pretreatment, magnetic separation was first used to remove impurities such as metal, stone, and sand, and then density separation was used to remove the plastic not made of polypropylene, then thermal pyrolysis was performed at 550 C. in the thermal pyrolysis unit 200 to obtain hydrocarbon oil and gas from thermal pyrolysis, and also ash was generated; [0096] (2) the hydrocarbon oil and gas from thermal pyrolysis obtained in step (1) was introduced to the gas-liquid separation unit 300 for gas-liquid separation to obtain crude plastic pyrolysis oil and pyrolysis gas; [0097] (3) the pyrolysis gas obtained in step (2) was introduced to the decarbonization unit 600, and decarbonization was performed at a temperature of 3500 C. and a pressure of 5 MPa by a high-temperature thermal pyrolysis technology to obtain a nano-carbon material and hydrogen, and the hydrogen was subjected to membrane separation, thus having a purity of 99.99%, and then used in step (4); [0098] (4) the crude plastic pyrolysis oil obtained in step (2) was sent to the hydrocracking unit 400 for hydrocracking at a temperature of 300 C. and a pressure of 15 MPa to obtain hydrotreated plastic pyrolysis oil; and [0099] (5) the hydrotreated plastic pyrolysis oil obtained in step (4) was sent to the fractionating unit 500 for fractionating to obtain the feed stock of ethylene steam cracker, a heavy component, and mixed hydrocarbon gas, where a fraction range of the feed stock of ethylene steam cracker was 65-400 C., a fraction range of the heavy component was 350-550 C., and the mixed hydrocarbon gas was C1-C4 gaseous hydrocarbon: the heavy component was returned to the hydrocracking unit 400 for use in the hydrocracking in step (4), and the mixed hydrocarbon gas was returned to the decarbonization unit 600 for use in the decarbonization in step (3).
Example 4
[0100] This example provides a method for producing feed stock of ethylene steam cracker and a nano-carbon material from waste plastics, which differs from Example 1 only in that the heavy component obtained by the fractionating was not used back for the hydrocracking in step (4).
[0101] This example provides a device system for producing feed stock of ethylene steam cracker and a nano-carbon material from waste plastics, which differs from Example 1 only in that the heavy-component outlet of the fractionating unit 500 was not connected to the inlet of the hydrocracking unit 400.
[0102] Compared to Example 1, the heavy component was not involved in hydrocracking in this example, reducing the yield of the feed stock of ethylene steam cracker by about 25%.
Example 5
[0103] This example provides a method for producing feed stock of ethylene steam cracker and a nano-carbon material from waste plastics, which differs from Example 1 only in that the mixed hydrocarbon gas obtained by the fractionating was not used back for the decarbonization in the step (3), and the hydrogen required for the hydrocracking was obtained by electrolysis for hydrogen production.
[0104] This example provides a device system for producing feed stock of ethylene steam cracker and a nano-carbon material from waste plastics, which differs from Example 1 only in that the gas-phase outlet of the fractionating unit 500 was not connected to the inlet of the decarbonization unit 600, and the gas-phase outlet of the decarbonization unit was not connected to the inlet of the hydrocracking unit.
[0105] Compared to Example 1, in this example, the mixed hydrocarbon gas was not used back for the decarbonization in step (3), thus failing to participate in the hydrogen production: the mixed hydrocarbon gas was combusted, which produced a large amount of carbon dioxide, and caused material loss; and the hydrogen of hydrocracking was obtained by the electrolysis for hydrogen production, which is more energy-consuming and costly.
Comparative Example 1
[0106] This comparative example provides a method for producing steam-cracking feedstock from waste plastics, which differs from Example 1 only in that the gas-liquid separation, decarbonization, and hydrocracking were not performed, and the method comprises the following steps: [0107] (1) the polyethylene waste plastic was pretreated, and in the pretreatment, magnetic separation was first used to remove impurities such as metal, stone, and sand, and then infrared separation was used to remove the plastic not made of polyethylene, then thermal pyrolysis was performed at 450 C. to obtain hydrocarbon oil and gas from thermal pyrolysis, and also ash was generated; and [0108] (2) the hydrocarbon oil and gas from thermal pyrolysis obtained in step (1) was fractionated to obtain plastic pyrolysis oil with a fraction range of 65-400 C. and plastic pyrolysis heavy oil with a fraction range of more than 400 C.
[0109] In this comparative example, the nano-carbon material cannot be obtained.
Comparative Example 2
[0110] This comparative example provides commercially available steam-cracking feedstock.
[0111] The total metal content, silicon content, chlorine content, nitrogen content, and oxygen content of the steam-cracking feedstock in Examples 1-5 and Comparative Examples 1-2 are shown in Table 1. The total metal content is measured by the methods of ASTM D5158, ASTM D711, UOP-946, UOP-952, and UOP-938; the silicon content is measured by the methods of ASTM D5158 and ASTM D711; the chlorine content is measured by ASTM D5808-18 method: the nitrogen content is measured by the methods of ASTM D4629 and ASTM D5762; and the oxygen content is measured by chromatography.
[0112] The alkane content, olefin content, and aromatic hydrocarbon and cycloalkane content of the steam-cracking feedstock in Examples 1-5 and Comparative Examples 1-2 are shown in Table 2. The chain alkane content, olefin content, and aromatic hydrocarbon and cycloalkane content are measured by SH/T0714 method.
[0113] Taking Example 1 as an example, the properties of the nano-carbon material in Example 1 are measured, and the results are shown in Table 3. The iodine absorption value is measured by GB/T 3780.1-2008 method: the DBP oil absorption is measured by HG/T 2152-2011 method; the CTAB adsorption specific surface area is measured by GB/T 3780.5-2008 method: the tinting strength is measured by GB/T 3780.6-2008 method: the heating loss is measured by GB/T 3780.8-2008 method: the ash content is measured by GB/T 3780.10-2008 method: the particle size is measured by GB/T 3781.5-2006 method; and the electrical resistivity is measured by GB/T 3781.9-2006 method.
TABLE-US-00001 TABLE 1 Metal (Fe, Na, Al, As, Cr, As, Pd, Hg) total Silicon Chlorine Nitrogen Oxygen content/ content/ content/ content/ content/ (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) Example 1 <1 <1 1 8 1 Example 2 <1 <1 1 10 1 Example 3 <1 <1 1 7 1 Example 4 <1 <1 1 8 1 Example 5 <1 <1 1 8 1 Comparative 1.6 466 16 85.6 8 Example 1 Comparative <1 <1 1 <10 Example 2 In Table 1, indicates that the value is not available.
TABLE-US-00002 TABLE 2 Chain alkane Olefin Aromatic hydrocarbon and content/wt % content/wt % cycloalkane content/wt % Example 1 93.1 0.9 6 Example 2 94.0 0.8 5.2 Example 3 92.4 0.6 7 Example 4 91.6 1.4 7 Example 5 93.1 0.9 6 Comparative 30.2 64 5.8 Example 1 Comparative 65.0 1.5 15 Example 2
TABLE-US-00003 TABLE 3 Example 1 Iodine absorption value/(g/kg) 412 DBP oil absorption/(ml/100 g) 230 10 CTAB adsorption specific surface area/(10.sup.3 m.sup.2/kg) 311 Tinting strength/% 102 Heating loss/wt % 0.3 Ash content/wt % 0.01 Partical size/nm 30 3 Electrical resistivity/( .Math. m) 2
[0114] The following can be seen from Tables 1-3.
[0115] (1) As can be seen from Examples 1-5, in the present application, the feed stock of ethylene steam cracker is obtained which has a stable quality and a low impurity content and satisfies the raw material demand of the downstream polyolefin plant, wherein the content of chain alkane can reach more than or equal to 91.6 wt %, the content of metal impurities and silicon is less than 1 mg/kg, and the content of chlorine, nitrogen, and oxygen is less than or equal to 10 mg/kg; taking Example 1 as an example, in the present application, the nano-carbon material with excellent performance can be obtained, which has a high purity, a high specific surface area, and a high structure, and has a broad application prospect.
[0116] (2) Compared to Comparative Examples 1-2, the steam-cracking feedstock obtained in Example 1 not only has a high purity, but also has a high content of chain alkane, which is more conducive to efficiently converting the steam-cracking feedstock to the target product such as olefin, propylene, and butadiene, while the steam-cracking feedstock obtained in Comparative Examples 1-2 has a high content of impurities and a high content of unsaturated hydrocarbon, and adversely produces a higher number of by-products when used to produce downstream products. It can be seen that the feed stock of ethylene steam cracker provided in the present application can achieve a higher yield of target product, and in the production process, the output of by-products and wastes is lower, and the downstream device is less prone to coking during operation.
[0117] In summary, the method and device system provided in the present application can produce the feed stock of ethylene steam cracker with excellent performance and the nano-carbon material with a high added value, which can reduce the treatment cost, avoid the generation of the waste and gas exhaust, and have high economic benefit and environmental benefit.
[0118] The applicant declares that the above is only the embodiments of the present application, but the protection scope of the present application is not limited thereto, and those skilled in the art should understand that any change or replacement which can be easily thought of by those skilled in the art within the technical scope disclosed in the present application falls within the scope of protection and disclosure of the present application.