High-pressure depolymerization of HDPE and PP

Abstract

1. A method of depolymerizing a polymeric material, comprising: (a) feeding a polymeric material to a depolymerization reactor maintained at a temperature in the range of 400°C to 600°C and operated under a pressure in the range of 4 to 15 barg; and (b) depolymerizing at least a portion of the polymeric material to form a first gaseous product and a first liquid product.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 250,997, filed under the Patent Cooperation Treaty and filed on September 30, 2021, the entire contents of which are incorporated herein by reference. Statement Regarding Federally Sponsored Research

[0002] Not applicable.

[0003] The present disclosure relates generally to a process for effectively depolymerizing polymeric materials under pressure. More specifically, the present disclosure relates to a process for depolymerizing polymeric materials under high pressure without the use of a catalyst. The polymeric materials depolymerized may include high density polyethylene and polypropylene. [Background technology]

[0004] Depolymerization followed by further processing such as hydrogenation or cracking offers an attractive method for converting polymer materials back to their raw materials. One problem with thermal depolymerization is that both polyethylene and polypropylene produce depolymerization liquids that contain large amounts of high molecular weight hydrocarbons, which complicates further processing. Summary of the Invention [Means for solving the problem]

[0005] One way to narrow the molecular weight distribution of the depolymerization liquor is to use a catalyst. However, catalysts suitable for depolymerization of plastics are often expensive, making the recycling process economically difficult to achieve. Furthermore, many catalysts can be contaminated by additives, pigments, and contaminants found in most target waste polymer material streams. Therefore, there is a need to reduce the amount of high molecular weight hydrocarbons in the depolymerization liquor obtained from polymer materials.

[0006] Generally, the present disclosure provides a method for depolymerizing a polymeric material, the method including: (a) feeding a polymeric material to a depolymerization reactor maintained at a temperature in the range of 400°C to 600°C and operated under a pressure in the range of 4 to 15 barg (58 to 218 psig); and (b) depolymerizing at least a portion of the polymeric material to form a first gaseous product and a first liquid product.

[0007] As used herein, the term "Cx" refers to a hydrocarbon having a specific number of carbon atoms. For example, C2 refers to a hydrocarbon having 2 carbon atoms, C8 refers to a hydrocarbon having 8 carbon atoms, C9+ refers to a hydrocarbon having 9 or more (9+) carbon atoms, etc.

[0008] As used herein, the term "depolymerization" refers to the breaking down of a polymer into smaller units or its monomers.

[0009] As used herein, "simulated distillation" is a method used to determine the true boiling point distribution of crude oil and refined petroleum fractions by gas chromatography. It is used as an alternative to time-consuming and labor-intensive physical distillation.

[0010] The following abbreviations are used herein: [Table 1]

[0011] This Summary is provided to introduce a selection of concepts that are further described below in the Detailed Description. However, many modifications are possible without substantially departing from the teachings of this disclosure. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined by the claims.

[0012] Specific embodiments of the present disclosure will now be described with reference to the accompanying drawings, in which like reference numerals refer to like elements. It should be understood, however, that the accompanying drawings are illustrative of various implementations described herein and are not intended to limit the scope of the various technologies described herein. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram illustrating an exemplary system according to one embodiment of the present disclosure. [Figure 2] FIG. 2 provides a comparison of boiling point data from Examples 1 and 2. [Figure 3] FIG. 3 provides a comparison of boiling point data from Example 3 and Run 41. [Figure 4] FIG. 4 presents a hydrocarbon analysis comparing depolymerization liquids obtained from polypropylene and high density polyethylene, according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0014] In the following description, numerous details are set forth to provide an understanding of some embodiments of the present disclosure. However, those skilled in the art will recognize that the systems and / or methods may be practiced without these details, and that many variations or modifications from the described embodiments are possible. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating general principles of implementation. The scope of the described implementations should be ascertained by reference to the issued claims.

[0015] The disclosure herein generally includes systems and methods for depolymerizing polymeric materials under high pressure. Depolymerization at high pressure can produce a depolymerized liquid containing reduced amounts of C9+ hydrocarbons compared to depolymerized liquids produced at lower (e.g., ambient) pressures. Using the systems and methods of the present disclosure, the C9+ hydrocarbon content in the depolymerized liquid can be reduced by 5%, 8%, 10%, 12%, 15%, or more compared to similar systems or methods operating at lower pressures. Surprisingly, such reductions can be achieved without the use of a catalyst.

[0016] As a result, the simulated distillation boiling point curves of depolymerized liquids produced in accordance with the present disclosure may decrease with increasing pressure. For polypropylene, the average boiling point depression across the entire curve is -33°C, with the highest quartile boiling point exhibiting an average decrease of -69°C. For polyethylene, the average boiling point depression across the entire curve is -35°C, with the highest quartile boiling point exhibiting an average decrease of -53°C. The effect of increasing pressure can be further confirmed in both specific gravity data and detailed hydrocarbon analysis by GC.

[0017] Generally, the present disclosure provides a method for depolymerizing a polymeric material, the method including: (a) feeding a polymeric material to a depolymerization reactor maintained at a temperature in the range of 400°C to 600°C and operated under a pressure in the range of 4 to 15 barg (58 to 218 psig); and (b) depolymerizing at least a portion of the polymeric material to form a first gaseous product and a first liquid product.

[0018] In some embodiments, the first liquid product has a composition comprising: (i) about 3.5 wt.% to about 6.0 wt.% C2-C4, (ii) about 6.5 wt.% to about 10.0 wt.% C5, (iii) about 11.7 wt.% to about 15.0 wt.% C6, (iv) about 5.0 wt.% to about 16.0 wt.% C7, (v) about 9.0 wt.% to about 16.0 wt.% C8, and (vi) less than about 59.5 wt.% C9+.

[0019] In some embodiments of the present disclosure, the method for depolymerizing a polymeric material further includes (c) sending the first liquid product to a cracking unit, wherein at least a portion of the liquid product is converted to one or more olefins. In some embodiments of the present disclosure, the cracking unit is a steam cracker. In some embodiments of the present disclosure, the cracking unit is a fluid catalytic cracking unit. In some embodiments of the present disclosure, the cracking unit is an olefins furnace.

[0020] In some embodiments of the present disclosure, when the polymeric material comprises polypropylene, the first liquid product has a composition comprising: (i) about 3.0 wt.% to about 4.5 wt.% C2-C4, (ii) about 7.5 wt.% to about 11.5 wt.% C5, (iii) about 12.5 wt.% to about 16.5 wt.% C6, (iv) about 4.2 wt.% to about 6.4 wt.% C7, (v) about 9.0 wt.% to about 13.0 wt.% C8, and (vi) less than about 57.5 wt.% C9+.

[0021] In some embodiments of the present disclosure, the polymeric material comprises at least 60% by weight polypropylene. In some embodiments of the present disclosure, the polymeric material comprises at least 65% by weight polypropylene. In some embodiments of the present disclosure, the polymeric material comprises at least 70% by weight polypropylene. In some embodiments of the present disclosure, the polymeric material comprises at least 75% by weight polypropylene. In some embodiments of the present disclosure, the polymeric material comprises at least 80% by weight polypropylene. In some embodiments of the present disclosure, the polymeric material comprises at least 85% by weight polypropylene. In some embodiments of the present disclosure, the polymeric material comprises at least 90% by weight polypropylene. In some embodiments of the present disclosure, the polymeric material comprises at least 95% by weight polypropylene. In some embodiments of the present disclosure, the polymeric material comprises at least 98% by weight polypropylene.

[0022] In some embodiments of the present disclosure, when the polymeric material comprises high-density polyethylene, the first liquid product has a composition comprising: (i) about 4.5% to about 6.5% by weight of C2-C4, (ii) about 5.5% to about 9.5% by weight of C5, (iii) about 11.5% to about 15.5% by weight of C6, (iv) about 12.0% to about 17.5% by weight of C7, (v) about 12.0% to about 17.5% by weight of C8, and (vi) less than about 50.0% by weight of C9+.

[0023] In some embodiments of the present disclosure, the polymeric material comprises at least 60% by weight of high density polyethylene. In some embodiments of the present disclosure, the polymeric material comprises at least 65% by weight of high density polyethylene. In some embodiments of the present disclosure, the polymeric material comprises at least 70% by weight of high density polyethylene. In some embodiments of the present disclosure, the polymeric material comprises at least 75% by weight of high density polyethylene. In some embodiments of the present disclosure, the polymeric material comprises at least 80% by weight of high density polyethylene. In some embodiments of the present disclosure, the polymeric material comprises at least 85% by weight of high density polyethylene. In some embodiments of the present disclosure, the polymeric material comprises at least 90% by weight of high density polyethylene. In some embodiments of the present disclosure, the polymeric material comprises at least 95% by weight of high density polyethylene. In some embodiments of the present disclosure, the polymeric material comprises at least 98% by weight of high density polyethylene.

[0024] In some embodiments of the present disclosure, the depolymerization is carried out in the absence of a catalyst. In some embodiments of the present disclosure, the depolymerization is carried out in the absence of molecular oxygen. In some embodiments of the present disclosure, the depolymerization is carried out in the absence of both a catalyst and molecular oxygen. In some embodiments of the present disclosure, the depolymerization is carried out in an inert atmosphere.

[0025] In some embodiments of the present disclosure, the reactor is operated at a temperature ranging from 400°C to 500°C. In some embodiments of the present disclosure, the reactor is operated at a temperature ranging from 400°C to 450°C. In some embodiments of the present disclosure, the reactor is operated at a temperature ranging from 425°C to 475°C. In some embodiments of the present disclosure, the reactor is operated at a temperature ranging from 425°C to 525°C. In some embodiments of the present disclosure, the reactor is operated at a temperature ranging from 450°C to 500°C. In some embodiments of the present disclosure, the reactor is operated at a temperature ranging from 450°C to 550°C. In some embodiments of the present disclosure, the reactor is operated at a temperature ranging from 475°C to 525°C. In some embodiments of the present disclosure, the reactor is operated at a temperature ranging from 475°C to 575°C. In some embodiments of the present disclosure, the reactor is operated at a temperature ranging from 500°C to 600°C. In some embodiments of the present disclosure, the reactor is operated at a temperature ranging from 500°C to 550°C. In some embodiments of the present disclosure, the reactor is operated at a temperature ranging from 525°C to 575°C. In some embodiments of the present disclosure, the reactor is operated at a temperature ranging from 550°C to 600°C.

[0026] In some embodiments of the present disclosure, the reactor is operated under a pressure in the range of 4 to 8 barg. In some embodiments of the present disclosure, the reactor is operated under a pressure in the range of 4 to 12 barg. In some embodiments of the present disclosure, the reactor is operated under a pressure in the range of 4 to 14 barg. In some embodiments of the present disclosure, the reactor is operated under a pressure in the range of 6 to 10 barg. In some embodiments of the present disclosure, the reactor is operated under a pressure in the range of 6 to 12 barg. In some embodiments of the present disclosure, the reactor is operated under a pressure in the range of 6 to 15 barg. In some embodiments of the present disclosure, the reactor is operated under a pressure in the range of 8 to 15 barg. In some embodiments of the present disclosure, the reactor is operated under a pressure in the range of 8 to 12 barg. In some embodiments of the present disclosure, the reactor is operated under a pressure in the range of 8 to 10 barg. In some embodiments of the present disclosure, the reactor is operated under a pressure in the range of 10 to 15 barg. In some embodiments of the present disclosure, the reactor is operated under a pressure in the range of 10 to 15 barg. In some embodiments of the present disclosure, the reactor is operated under a pressure in the range of 12 to 15 barg. In some embodiments of the present disclosure, the reactor is operated under a pressure in the range of 12 to 14 barg.

[0027] In some embodiments of the present disclosure, at least a portion of the polymeric material is a polymeric material from post-industrial waste. In some embodiments of the present disclosure, the polymeric material is a polymeric material from industrial waste. In some embodiments of the present disclosure, at least a portion of the polymeric material is a polymeric material from post-consumer waste. In some embodiments of the present disclosure, the polymeric material is a polymeric material from post-consumer waste.

[0028] In some embodiments of the present disclosure, the polymeric material is washed before being fed to the depolymerization reactor. In some embodiments of the present disclosure, the polymeric material is washed with water before being fed to the depolymerization reactor.

[0029] In some embodiments of the present disclosure, the polymeric material is a blend of two or more polymeric materials, which may include polyethylene, polypropylene, high-density polyethylene, low-density polyethylene, linear low-density polyethylene, and ultra-high-density polyethylene.

[0030] FIG. 1 provides a diagram illustrating a system 100 according to one embodiment of the present disclosure. A feed of polymeric material 110 is fed to a depolymerization reactor 120. The polymeric material 110 is depolymerized in the depolymerization reactor 120 under high pressure and without the use of a catalyst to form a gaseous product 130 and a liquid product 140. The gaseous product 130 is discharged from the depolymerization reactor 120 and may be sent to a collection unit (not shown) or incorporated into another chemical process (not shown). The liquid product 140 is collected from the depolymerization reactor 130 and may optionally be sent to one or more processing units 150. The processing units 150 may include one or more processes (e.g., purification, filtration, chemical reaction, physical separation, etc.) that act on the liquid product 140 to produce a treated liquid 160. The liquid product 140, or the treated liquid 160 if an optional processing unit is used, may be directed to a cracking unit 170, where the liquid product 140 (or possibly the treated liquid 160) is at least partially converted to one or more olefins 180.

[0031] The following examples are merely illustrative of the systems and methods of the present disclosure, and those skilled in the art will recognize many variations that are within the spirit of the disclosure and scope of the claims. [Example]

[0032] Examples 1 to 4 Depolymerization of the polymeric material was carried out in a 1.8 L Hastelloy C276 reactor equipped with an agitator and heated by a furnace. The polymeric material was added to the reactor, and the reactor was sealed. A nitrogen gas (N2) purge was established through the reactor and downstream equipment, including a heated overhead line and two product collection vessels maintained at ambient temperature. The overhead line consisted of a vertical section maintained at 150°C and a downward sloping line maintained at 100°C, feeding the product collection vessel. The reactor pressure was controlled by a backpressure regulator.

[0033] The furnace was set to 500°C, and then heating of the reactor was initiated. Once the furnace temperature reached 200°C, the N2 purge was reduced to 50 standard cubic centimeters per minute (sccm). Once the internal temperature reached 200°C, the agitator was started at 60 rpm. The internal temperature was monitored until an inflection point was observed in the time-dependent temperature curve, indicating the onset of depolymerization. Once this point was observed, the reaction was continued for an additional 3 hours. The reactor was then cooled, and the liquid product was collected and weighed. The reactor was opened, and the solid was removed and weighed. The gas yield was calculated by difference.

[0034] The polymeric materials to be depolymerized were the LyondellBasell products HP522 (PP) and Hostalen ACP 9255 Plus (HDPE). calculation

[0035] Liquid product samples were characterized by gas chromatography using an Agilent 7890 equipped with a non-polar column and FID. GC data used to characterize liquids can typically be classified by carbon atom number.

[0036] Additionally, simulated distillation was used to characterize the liquid products. Simulated distillation data for the liquid samples was collected using ASTM D7213 on an Agilent 6980. The simulated distillation data used to characterize the liquids provides the boiling range distribution of the light and medium petroleum fractions, which can provide insight into the composition of the feedstock and products.

[0037] In Example 1, HP522 PP was depolymerized at 30 psig pressure, while in Example 2, HP522 PP was depolymerized at 90 psig pressure. In Example 3, Hostalen ACP 9255 Plus was depolymerized at 30 psig pressure, while in Example 4, the same plastic was depolymerized at 90 psig pressure. The results are shown in Table 1 and Figures 1-3. [Table 2]

[0038] As can be seen from Table 1, the depolymerization onset temperatures for Examples 1-2 (PP) and 3-4 (HDPE) are comparable. The liquid yield at high pressure for Example 2 (86%) is slightly lower than that for Example 1 (89%). Similar results are also found between Example 4 (76%) and Example 3 (80%) at higher pressures. This indicates that depolymerization under high pressure favors the production of lower molecular weight products, as evidenced by the increased gas yields in Examples 2 and 4 (14%, 21%) compared to Examples 1 and 3 (10%, 19%).

[0039] Table 2 shows the specific gravity and simulated distillation data for Examples 1-4. As can be seen, all boiling points in Table 2, except for IBP (initial boiling point), are lower at 90 psig compared to 30 psig. The specific gravity of both polymers at 90 psig is also lower compared to 30 psig. Specific gravity is a measure of the chain length of a polymer, with lower specific gravity indicating a shorter average chain length. Therefore, increasing the pressure in the depolymerization reactor effectively reduces chain length. [Table 3]

[0040] Figure 2 shows the simulated distillation data for polypropylene in Examples 1 and 2, and Figure 3 shows the simulated distillation data for HDPE in Examples 3 and 4. Numerical results are provided in Table 3.

[0041] As can be seen in Figure 2, the boiling point of Example 2 (dotted line) is lower than that of Example 1 (solid line) throughout the process. Similarly, in Figure 3, the boiling point of Example 4 (dotted line) is lower than that of Example 3 (solid line) throughout the process. A lower boiling point means that less energy is needed to heat the reactor to effectively carry out the depolymerization reaction, and maintaining the same temperature can result in more complete depolymerization and shorter chain products that are more suitable for further processing. [Table 4]

[0042] Additionally, the average boiling point depression for polypropylene was calculated by subtracting the boiling point at 30 psig from the boiling point at 90 psig for each point along the simulated distillation curves of Examples 1 and 2 and averaging them across the entire curve as well as over the four quartiles (Table 4). The same process was performed for high density polyethylene, and its average boiling point depression is also shown in Table 4. [Table 5]

[0043] For polypropylene, the average boiling point depression across the curve was −33° C., with the highest quartile boiling point exhibiting an average depression of −69° C. For high-density polyethylene, the average boiling point depression across the curve was −35° C., with the highest quartile boiling point exhibiting an average depression of −53° C.

[0044] A detailed hydrocarbon analysis was performed on the depolymerization liquid and the summary data are shown in Table 5. Figure 4 shows a visualization of the distribution of the various hydrocarbons. [Table 6]

[0045] As can be seen, the yield of preferred short-chain hydrocarbons (C2-C8) increased overall. Specifically, for high-density polyethylene, the largest increase occurred for C7 (an increase of approximately 4.5 wt%), while for PP, the largest increases occurred for C6 and C8, each increasing by approximately 3 wt%.

[0046] The unwanted C9+ hydrocarbons were also significantly reduced. In the case of polyethylene, the yield of C9+ hydrocarbons decreased by approximately 12 wt%. In the case of high-density polyethylene, the yield of C9+ hydrocarbons decreased by almost 18 wt%. This again indicates that the high pressure of 90 psig during depolymerization plays an important role in lowering the boiling point while improving the hydrocarbon distribution.

[0047] Therefore, the present disclosure provides a novel process for molecularly recycling plastic waste, particularly for polypropylene and polyethylene. By increasing the pressure in the depolymerization reactor, the boiling points of the depolymerized solutions produced from polypropylene and high-density polyethylene, respectively, were significantly reduced. The reduced boiling point reduces the reaction temperature, thereby reducing the cost of depolymerization. Furthermore, the reduced boiling point means more complete depolymerization, resulting in less production of long-chain C9+ hydrocarbons. Additional Disclosures

[0048] Embodiments disclosed herein include the following:

[0049] A: A method for depolymerizing a polymeric material, the method comprising: (a) feeding a polymeric material to a depolymerization reactor maintained at a temperature in the range of 400°C to 600°C and operated under a pressure in the range of 4 to 15 barg (58 to 218 psig); and (b) depolymerizing at least a portion of the polymeric material to form a first gaseous product and a first liquid product.

[0050] Embodiment A may include one or more of the following additional elements:

[0051] Element 1: The first liquid product has a composition including: (i) about 3.5 wt% to about 6.0 wt% C2-C4, (ii) about 6.5 wt% to about 10.0 wt% C5, (iii) about 11.7 wt% to about 15.0 wt% C6, (iv) about 5.0 wt% to about 16.0 wt% C7, (v) about 9.0 wt% to about 16.0 wt% C8, and (vi) less than about 59.5 wt% C9+.

[0052] Element 2:(c) further comprising the step of passing the first liquid product to a cracking unit, wherein at least a portion of the liquid product is converted to one or more olefins.

[0053] Element 3: When the polymeric material comprises polypropylene, the first liquid product has a composition comprising: (i) about 3.0 wt% to about 4.5 wt% C2-C4, (ii) about 7.5 wt% to about 11.5 wt% C5, (iii) about 12.5 wt% to about 16.5 wt% C6, (iv) about 4.2 wt% to about 6.4 wt% C7, (v) about 9.0 wt% to about 13.0 wt% C8, and (vi) less than about 57.5 wt% C9+.

[0054] Element 4: The polymeric material comprises at least 60% by weight polypropylene. In some embodiments of the present disclosure, the polymeric material comprises at least 65% by weight polypropylene. Element 5: The polymeric material comprises at least 70% by weight polypropylene. Element 6: The polymeric material comprises at least 75% by weight polypropylene. Element 7: The polymeric material comprises at least 80% by weight polypropylene. Element 8: The polymeric material comprises at least 85% by weight polypropylene. Element 9: The polymeric material comprises at least 90% by weight polypropylene. Element 10: The polymeric material comprises at least 95% by weight polypropylene. Element 11: The polymeric material comprises at least 98% by weight polypropylene.

[0055] Element 12: When the polymeric material comprises high-density polyethylene, the first liquid product has a composition comprising: (i) about 4.5% to about 6.5% by weight of C2-C4, (ii) about 5.5% to about 9.5% by weight of C5, (iii) about 11.5% to about 15.5% by weight of C6, (iv) about 12.0% to about 17.5% by weight of C7, (v) about 12.0% to about 17.5% by weight of C8, and (vi) less than about 50.0% by weight of C9+.

[0056] Element 13: The polymeric material comprises at least 60% by weight of high density polyethylene. Element 14: The polymeric material comprises at least 65% by weight of high density polyethylene. Element 15: The polymeric material comprises at least 70% by weight of high density polyethylene. Element 16: The polymeric material comprises at least 75% by weight of high density polyethylene. Element 17: The polymeric material comprises at least 80% by weight of high density polyethylene. Element 18: The polymeric material comprises at least 85% by weight of high density polyethylene. Element 19: The polymeric material comprises at least 90% by weight of high density polyethylene. Element 20: The polymeric material comprises at least 95% by weight of high density polyethylene. Element 21: The polymeric material comprises at least 98% by weight of high density polyethylene.

[0057] Element 22: The depolymerization is carried out in the absence of a catalyst. Element 23: The depolymerization is carried out in the absence of molecular oxygen. Element 24: The depolymerization is carried out in the absence of both a catalyst and molecular oxygen. Element 25: The depolymerization is carried out in an inert atmosphere.

[0058] Element 26: The reactor is operated at a temperature ranging from 400°C to 500°C. Element 27: The reactor is operated at a temperature ranging from 400°C to 450°C. Element 28: The reactor is operated at a temperature ranging from 425°C to 475°C. Element 29: The reactor is operated at a temperature ranging from 425°C to 525°C. Element 30: The reactor is operated at a temperature ranging from 450°C to 500°C. Element 31: The reactor is operated at a temperature ranging from 450°C to 550°C. Element 32: The reactor is operated at a temperature ranging from 475°C to 525°C. Element 33: The reactor is operated at a temperature ranging from 475°C to 575°C. Element 34: The reactor is operated at a temperature ranging from 500°C to 600°C. Element 35: The reactor is operated at a temperature ranging from 500°C to 550°C. Item 36: The reactor is operated at a temperature ranging from 525°C to 575°C. Item 37: The reactor is operated at a temperature ranging from 550°C to 600°C.

[0059] Element 38: The reactor is operated under a pressure in the range of 4 to 8 barg. Element 39: The reactor is operated under a pressure in the range of 4 to 12 barg. Element 40: The reactor is operated under a pressure in the range of 4 to 14 barg. Element 41: The reactor is operated under a pressure in the range of 6 to 10 barg. Element 42: The reactor is operated under a pressure in the range of 6 to 12 barg. Element 43: The reactor is operated under a pressure in the range of 6 to 15 barg. Element 44: The reactor is operated under a pressure in the range of 8 to 15 barg. Element 45: The reactor is operated under a pressure in the range of 8 to 12 barg. Element 46: The reactor is operated under a pressure in the range of 8 to 10 barg. Element 47: The reactor is operated under a pressure in the range of 10 to 15 barg. Element 48: The reactor is operated under a pressure in the range of 10 to 15 barg. Element 49: The reactor is operated under a pressure in the range of 12 to 15 barg. Element 50: The reactor is operated under a pressure in the range of 12 to 14 barg.

[0060] Element 51: At least a portion of the polymeric material is a polymeric material from post-industrial waste. Element 52: The polymeric material is a polymeric material from post-industrial waste. Element 53: At least a portion of the polymeric material is a polymeric material from post-consumer waste. Element 54: The polymeric material is a polymeric material from post-consumer waste.

[0061] Element 55: The polymeric material is washed before being fed to the depolymerization reactor. Element 56: The polymeric material is washed with water before being fed to the depolymerization reactor.

[0062] Element 57: The polymeric material is a blend of two or more polymeric materials. Element 58: The polymeric material may include polyethylene, polypropylene, high density polyethylene, low density polyethylene, linear low density polyethylene, and ultra high density polyethylene.

[0063] Element 59: The cracking unit is a steam cracker. Element 60: The cracking unit is a fluid catalytic cracking unit. Element 61: The cracking unit is an olefin furnace.

[0064] The specific embodiments disclosed above are illustrative only, as the disclosure may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It will therefore be apparent that the specific exemplary embodiments disclosed above may be altered or modified, and all such variations are considered to be within the scope and spirit of the disclosure. Alternative embodiments obtained by combining, integrating, and / or omitting features of the embodiment(s) are also within the scope of the disclosure. While compositions and methods are described in broader terms such as "having," "comprising," "containing," or "including" various components or steps, compositions and methods can also "consist essentially of," or "consist of," various components or steps. The use of the term "optionally" with respect to any element of a claim means either the presence of the element or the absence of the element; both alternatives are within the scope of the claim. Within the claims, means-plus-function claims are intended to cover the structures described herein that perform the recited function(s) and structural equivalents as well as equivalent structures. It is Applicant's express intent not to invoke 35 U.S.C. 112, paragraph 6, as to any limitation of any claim herein unless the claim expressly uses the term "means for" with the associated function.

[0065] The numbers and ranges disclosed above may vary by a certain amount. Whenever a numerical range with a lower and upper limit is disclosed, any number falling within that range and any included range is specifically disclosed. In particular, all ranges of values ​​disclosed herein (in the form "about a to about b," or, equivalently, "about a to b," or, equivalently, "about a to b") should be understood to represent all numbers and ranges encompassed within the broader range of values. Furthermore, terms in the claims have their plain and ordinary meaning unless expressly and unambiguously defined otherwise by the patent owner. Furthermore, the indefinite article "a" or "an," as used in the claims, is defined herein to mean one or more of the elements it introduces. In the event of a discrepancy in the use of a word or term in this specification and one or more patents or other documents, the consistent definition in this specification should prevail.

[0066] The term "about" refers to the stated value plus or minus the range of measurement error, or plus or minus 10% if the measurement method is not indicated.

[0067] Use of the term "or" in the claims means "and / or," unless expressly stated to refer to only alternatives or where alternatives are mutually exclusive.

[0068] The terms "comprise," "have," "include," and "contain" (and variations thereof) are open-ended linking verbs that, when used in the claims, allow for the addition of other elements.

[0069] The phrase "consisting of" is closed and excludes all additional elements.

[0070] The phrase "consisting essentially of" excludes additional significant elements, but allows for the inclusion of minor elements that do not materially alter the essence of the invention.

[0071] Accordingly, the scope of protection is not limited by the description set out above, but is limited only by the claims that follow, that scope including equivalents of the subject matter of the claims.

Claims

1. 1. A method for depolymerizing a polymeric material, comprising: (a) feeding a polymeric material to a depolymerization reactor maintained at a temperature in the range of 400°C to 600°C and operated under a pressure in the range of 4 to 15 barg (58 to 218 psig); (b) depolymerizing at least a portion of the polymeric material to form a first gaseous product and a first liquid product, the first liquid product comprising: (i) about 3.5% to about 6.0% by weight of C2-C4; (ii) about 6.5 wt.% to about 10.0 wt.% C5; (iii) about 11.7 wt.% to about 15.0 wt.% C6; (iv) about 5.0 wt.% to about 16.0 wt.% C7; (v) about 9.0% to about 16.0% by weight of C8, and (vi) having a composition comprising less than about 59.5 wt.% C9+, wherein the depolymerization is conducted in the absence of a catalyst.

2. 10. The method of depolymerizing a polymeric material according to claim 1, further comprising: (c) sending the first liquid product to a steam cracker or a fluid catalytic cracking unit, wherein at least a portion of the liquid product is converted to one or more olefins.

3. When the polymeric material comprises polypropylene, the first liquid product comprises: (i) about 3.0% to about 4.5% by weight of C2-C4; (ii) about 7.5 wt.% to about 11.5 wt.% C5; (iii) about 12.5 wt.% to about 16.5 wt.% C6; (iv) about 4.2% to about 6.4% by weight of C7; (v) about 9.0% to about 13.0% by weight of C8, and 10. The method of claim 1, wherein the polymeric material has a composition comprising: (vi) less than about 57.5 wt.% C9+.

4. 4. The method of depolymerizing a polymeric material according to claim 3, wherein the polymeric material comprises at least 85% by weight of polypropylene.

5. When the polymeric material comprises high density polyethylene, the first liquid product comprises: (i) about 4.5% to about 6.5% by weight of C2-C4; (ii) about 5.5 wt.% to about 9.5 wt.% C5; (iii) about 11.5 wt.% to about 15.5 wt.% C6; (iv) about 12.0 wt. % to about 17.5 wt. % C7; (v) about 12.0% to about 17.5% by weight of C8, and 10. The method of claim 1, wherein the polymeric material has a composition comprising: (vi) less than about 50.0 wt. % C9+.

6. 6. The method of depolymerizing a polymeric material according to claim 5, wherein the polymeric material comprises at least 85% by weight of high density polyethylene.

7. 10. The method of claim 1, wherein the depolymerization is carried out in the absence of molecular oxygen.

8. 10. The method of claim 1, wherein the depolymerization is carried out in an inert atmosphere.

9. 10. The method of claim 1, wherein the reactor is operated at a temperature in the range of 400°C to 500°C.

10. 10. The method of claim 1, wherein the reactor is operated at a temperature in the range of 450°C to 550°C.

11. 10. The method of claim 1, wherein the reactor is operated at a temperature in the range of 500°C to 600°C.

12. 10. The method of claim 1, wherein the reactor is operated under a pressure in the range of 10 to 15 barg.

13. 2. The method of claim 1, wherein the reactor is operated under a pressure in the range of 6 to 12 barg.

14. 10. The method of claim 1, wherein the reactor is operated under a pressure in the range of 4 to 8 barg.

15. 10. The method for depolymerizing a polymeric material according to claim 1, wherein the polymeric material is a polymeric material from an industrial waste product.

16. 10. The method of claim 1, wherein the polymeric material is a post-consumer polymeric material.

17. 10. The method of claim 1, wherein the polymeric material is washed before being fed to the depolymerization reactor.

18. 10. The method of claim 1, wherein the polymeric material is a mixture of two or more polymeric materials.

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