PROCESS FOR REMOVING INORGANIC CONTAMINANTS FROM PYROLYSIS OILS BY ALKALI HYDROXIDE TO PRODUCE HIGH QUALITY STEAM CRACKER FEEDSTOCKS

Abstract

A novel process for making steam cracker feedstocks from contaminated pyrolysis oil, e.g., derived from waste plastics. The process utilizes an alkali hydroxide hydrolysis to clean the pyrolysis oil. The clean pyrolysis oil is then sent to an isocracking section to prepare high quality steam cracker feedstock. Some products can be sent to a steam cracker as feedstocks, while others can be recycled back into the system to improve feedstock yield. This recycling can also be done for better heat management.

Claims

1. A process for treating pyrolysis oil comprising: a) mixing the pyrolysis oil and an alkali hydroxide solution; b) allowing the mixture of a) to react, wherein the reaction time ranges from 2 to 4 hours; the reaction temperature is in the range of from 250 C. to 350 C.; and the pressure in the reaction in step b) is in the range of 900 to 1200 psi.

2. (canceled)

3.

4. (canceled)

5. (canceled)

6. (canceled)

7. (canceled)

8. (canceled)

9. The process of claim 1, wherein the alkali hydroxide comprises sodium hydroxide or other alkali hydroxide.

10. The process of claim 8, wherein the mixture in a) further comprises an alkaline earth metal hydroxide.

11. The process of claim 8, wherein the mixture in a) further comprises ammonium hydroxide or an organic amine.

12. The process of claim 1, wherein at least 90 wt. % of Cl, Si, and metal contaminants are removed.

13. The process of claim 11, wherein the metal contaminants comprise Zn and Fe.

14. The process of claim 1, wherein the pyrolysis oil is derived from pyrolysis of plastic.

15. The process of claim 13, wherein the plastic is waste plastic.

16. The process of claim 1, wherein the pyrolysis oil is bio-derived pyrolysis oil.

17. The process of claim 1, wherein the pyrolysis oil is derived from general waste.

18. The process of claim 1, wherein the pyrolysis oil and alkali hydroxide is mixed in a volume ratio of 5/95 to 95/5.

19. The process of claim 17, wherein the volume ratio ranges from 25/75 to 75/25.

20. The process of claim 17, wherein the volume ratio is about 50/50.

21. The process of claim 1, wherein a pyrolysis oil is recovered from the reaction and then forwarded to an isoconversion reaction section.

22. The process of claim 20, wherein the isoconversion reaction section comprises a hydrotreating subsection and an isocracking subsection.

23. The process of claim 1, wherein a pyrolysis oil is recovered from the reaction in b), hydrotreated and effluent from the hydrotreatment is hydrocracked.

24. The process of claim 1, wherein a pyrolysis oil is first hydrotreated, and then mixed and reacted with an alkali hydroxide solution.

25. The process of claim 23, wherein after the reaction of the mixture, reaction effluent from the reaction is hydrotreated.

26. The process of claim 1, wherein after the reaction of the mixture, reaction effluent from the reaction is hydrotreated.

27. The process of claim 25, wherein effluent from the hydrotreating of the reaction effluent is hydrotreated.

28. The process of claim 20, wherein a product is recovered from the isoconversion reaction section, with at least a portion of the recovered product passed to a steam cracker.

29. The process of claim 22, wherein a hydrocracked product is recovered and passed to a steam cracker.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The following detailed description of specific embodiments of the disclosure will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the disclosure, specific embodiments are shown in the drawings. It should be understood, however, that the disclosure is not limited to the precise arrangements and instrumentalities of the embodiments shown in the drawings.

[0010] FIGS. 1, 2, and 3 provide process flow diagrams for converting pyrolysis oils with contaminants to a steam cracker feed in accordance with the present process. Each process employs a pyrolysis oil hydrolysis step in accordance with the present process in front of a conversion section.

[0011] FIG. 1 shows a process flow diagram in which the pyrolysis oil is hydrolyzed and then passed to a two stage hydrotreating reactor.

[0012] FIG. 2 shows a process flow diagram in which the pyrolysis oil is first passed to a first stage of a two stage hydrotreating reactor, then to a hydrolysis reactor, and then the second stage of the hydrotreating reactor.

[0013] FIG. 3 shows a process flow diagram where the pyrolysis oil is passed to a hydrolysis reactor and then to a single stage hydrotreating reactor.

DETAILED DESCRIPTION

[0014] Before the present process for making steam cracker feedstocks from pyrolysis oil derived from waste plastics, is disclosed and described, it is to be understood that this disclosure is not limited to the particular structures, process steps, or materials disclosed herein, but is extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting. It must be noted that, as used in this specification, the singular forms a, an, and the include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a step may include multiple steps, reference to producing or products of a reaction or treatment should not be taken to be all of the products of a reaction/treatment, and reference to treating may include reference to one or more of such treatment steps. As such, the step of treating can include multiple or repeated treatment of similar materials/streams to produce identified treatment products.

[0015] Numerical values with about include typical experimental variances. As used herein, the term about means within a statistically meaningful range of a value, such as a stated particle size, concentration range, time frame, molecular weight, temperature, or pH. Such a range can be within an order of magnitude, typically within 10%, and more typically within 5% of the indicated value or range. Sometimes, such a range can be within the experimental error typical of standard methods used for the measurement and/or determination of a given value or range. The allowable variation encompassed by the term about will depend upon the particular system under study, and can be readily appreciated by one of ordinary skill in the art. Whenever a range is recited within this application, every whole number integer within the range is also contemplated as an embodiment of the invention.

[0016] This disclosure describes a hydrolysis process that can remove significant amounts of contaminants such as Cl, Si, and metals from pyrolysis oils with high amounts of contaminants. It has been found that the present alkali hydroxide hydrolysis reaction can remove at least 90 wt. %, or even more, of such contaminants. At the same time, the present process improves processability allowing the production of high quality steam cracker feed.

[0017] The alkali hydroxide used can be any suitable alkali hydroxide. Sodium hydroxide is used in one embodiment, and is preferred. In addition to the alkali hydroxide, other agents can also be used therewith. Alkaline-earth metal hydroxides such as calcium or magnesium hydroxide can be used together with the alkali hydroxide. High pH, basic pH, agents can also be present. For example, ammonium hydroxide or organic amines can be used together with the alkali hydroxide in one embodiment. The amount of the additional agents can vary, but generally, would be such as to not negatively impact the effectiveness of the alkali hydroxide.

[0018] The process can be used successfully on any pyrolysis oil containing contaminants. The pyrolysis oil can be derived from plastics, any plastic. The pyrolysis oil can be bio-derived pyrolysis oil, or derived from general waste, tires, etc. Any pyrolysis oil containing contaminants, can be successfully cleaned by the present hydrolysis process using an alkali hydroxide.

[0019] The hydrolysis process comprises treatment of the contaminated pyrolysis oil with an alkali hydroxide solution, in particular a sodium hydroxide (NaOH) solution. The pyrolysis oil and alkali hydroxide are mixed and placed in a reactor. The temperature and pressure are raised. The temperature and reaction time can vary. The reaction temperature can range from about 25 C. to about 550 C. The reaction time can be at least 2 minutes. Generally, it can range from about 2 minutes to 10 hours, as is appropriate. The pressure in the reaction can generally range from 15 to 3000 psi. Higher temperatures, such as 250 C. to 350 C., e.g., in one embodiment around 280 C., and longer reaction times, such as 2 to 4 hours, e.g., in one embodiment about 3 hours, favor higher contaminant records. Higher pressures, such as 900 to 1200 psi, has also enhanced contaminant removal.

[0020] The present hydrolysis process significantly removes contaminants found in raw pyrolysis oil. The present pyrolysis process employing an alkali hydroxide, such as NaOH, produces a clear pyrolysis oil which can be used as feed to a conversion reaction section, e.g., isoconversion with isocracking, or conversion with cracking, such as hydrocracking. The clean pyrolysis oil feed allows the downstream conversion reaction section to use less amount of demetallization catalyst and lower cost steel allow reactors. The pyrolysis oil hydrolysis reactor using the alkali hydroxide can be either batch or continuous unit.

[0021] This disclosure also describes a process for making steam cracker feedstocks from pyrolysis oil derived from waste plastics. In one embodiment, the present process for the conversion of waste plastic derived pyrolysis oil into steam cracker feedstock includes two sections. The pyrolysis oil hydrolysis section discussed above, and an isoconversion or hydrocracking section. In one embodiment, the process is seen under liquid single stage recycle (SSREC) operational mode. Hydrolysis and isoconversion/hydrocracking are distinctly different catalytic processes, but which also operate at pressures greater than atmospheric in the presence of hydrogen.

[0022] The present pyrolysis oil reaction generally comprises mixing NaOH solution and pyrolysis oil in a reactor. The ratio can vary but is generally about 50/50 vol/vol. A volume ratio of alkali hydroxide solution to pyrolysis oil in the range of 5/95 to 95/5, or 25/75 to 75/25 can generally be effective. The reactor is then sealed and raised to a target temperature and pressure for a target reaction time.

[0023] The clean pyrolysis oil is recovered from the reactor and passed to a conversion reaction section such as an isoconversion reaction section. An isoconversion reaction section can comprise a HDT (hydrotreating) section and an isocracking section. The HDT section can comprise more than one HDT reactor. Any suitable conversion reaction section as is known can be used for reacting and converting the clean pyrolysis oil.

[0024] The product from the conversion reaction section can then be passed as a quality steam cracker feedstock to a steam cracker.

[0025] Turning to the Figures of the Drawings, a first innovative process is shown in FIG. 1 of the Drawing. A pyrolysis oil hydrolysis step 1060 is added in front of an isoconversion reaction section. The conversion reaction section includes HDT and cracking sub sections. The pyrolysis oil hydrolysis process will significantly remove contaminants in raw pyrolysis oil in order to produce a clean pyrolysis oil as feed for the conversion reaction section, which allows the downstream conversion reaction section to use less amount of demetallization catalysts and lower cost steel alloy reactors. The pyrolysis oil hydrolysis reactor could be either a batch or a continuous unit.

[0026] More specifically, in FIG. 1, caustic alkali hydroxide, e.g., NaOH, 1050 is added to plastic derived pyrolysis oil 1001. Other alkali hydroxides can also be used but NaOH is preferred. Other agents such as alkaline earth metal hydroxides, ammonium hydroxide, or organic amines can also be present. A hydrolysis reaction is conducted in a reactor 1060 to provide clean pyrolysis oil. The clean pyrolysis oil is passed to a first stage hydrotreating reactor 1002. Wastewater 1061 from the hydrolysis reactor 1060 is passed to a total wastewater management system 1062. H.sub.2 1000, along with the clean pyrolysis oil can be provided to the first stage hydrotreating reactor 1002. The effluent of the first stage hydrotreating reactor 1002 can be passed to a second stage hydrotreating reactor 1003, wherein amine 1005 can be injected to the effluent of the hydrotreating reactor 1003, before the effluent is passed to a hydrotreating separation stage 1004. The hydrotreating separation stage 1004 produces wastewater 1006, recycle H.sub.2 1007 (which can be sent back to the first stage hydrotreating reactor 1002), C.sub.4-gasses 1008, and an hydrotreatment separation effluent 1009. The hydrotreatment separation effluent 1009 can be passed to an isocracking stage 1010 along with fresh H.sub.2 1011. The reaction is conducted under conventional isocracking reaction conditions. The effluent of the isocracking stage 1010 can be injected with amine 1012 before being passed to an isocracking separation stage 1013. The isocracking separation stage 1013 produces wastewater 1014, recycle H.sub.2 1025 (which can be sent back to isocracking stage 1010), C.sub.4-gasses 1016, and an isocracking separation effluent 1017. The isocracking separation effluent can be passed to an isocracking fractionation stage 1018, and/or recycled 1019 back to the first stage hydrotreating reactor 1002 and/or the isocracking stage 1010 as recycle diesel or water soluble liquid product (WLP) 1019. The isocracking fractionation stage can produce diesel 1020, jet fuel 1021, and naphtha 1022. The naphtha 1022 can be passed to a steam cracker 1023, along with the C.sub.4-gasses 1008.

[0027] As shown in FIG. 2 of the Drawing, a pyrolysis oil hydrolysis step 2060 is added between stage I HDT and stage II HDT sub sections.

[0028] More specifically, in FIG. 2, fresh H.sub.2 2000, along with waste plastic derived pyrolysis oil 2001 can be provided to a first stage hydrotreating reactor 2002. Caustic alkali hydroxide, alone or with other basic agents, 2050, is added to the effluent of the first stage hydrotreating reactor 2002, which mixture can be passed to a hydrolysis reactor 2060 in which a hydrolysis reaction is conducted with the alkali hydroxide caustic to provide a cleaner pyrolysis oil. Wastewater 2061 from the reactor 2060 is passed to a wastewater management system 2062. The cleaner pyrolysis oil is passed to a second stage hydrotreating reactor 2028, wherein amine 2005 can be injected to the effluent of hydrotreating reactor 2028, before the effluent is passed to a hydrotreating separation stage 2004. The hydrotreating separation stage 2004 produces wastewater 2006, recycle H.sub.2 2007 (which can be sent back to the first stage hydrotreating reactor 2002), C.sub.4-gasses 2008, and an hydrotreatment separation effluent 2009. The hydrotreatment separation effluent 2009 can be passed to an isocracking stage 2010 to which fresh H.sub.2 is added 2011. The effluent of the isocracking stage 2010 can be injected with amine 2012 before being passed to an isocracking separation stage 2017. The isocracking separation stage 2017 produces wastewater 2014, recycle H.sub.2 2015 (which can be sent back to isocracking stage 2010), C.sub.4-gasses 2016, and an isocracking separation effluent 2025. The isocracking separation effluent can be passed to an isocracking fractionation stage 2018, and/or recycled back to the first stage hydrotreating reactor 2002 and/or the isocracking stage 2010 as recycle diesel or WLP 2019. The isocracking fractionation stage 2018 can produce diesel 2020, jet fuel 2021, and naphtha 2022. The naphtha 2022 can be passed to a steam cracker 2023, along with the C.sub.4-gasses 2008 and 2016.

[0029] In FIG. 3, a process is shown which employs a single stage hydrotreating reactor. Caustic, generally comprising sodium hydroxide, 3050, is added to plastic derived pyrolysis oil 3001. The mixture is then passed to a hydrolysis reactor 3060 in which a hydrolysis reaction is conducted. Hydrogen 3000 is also passed to the hydrolysis reactor. In FIG. 3, the hydrolysis reactor is a SILIGON Si hydrolysis reactor. Effluent from the hydrolysis reactor is then passed to a single stage hydrotreating reactor 3002. Wastewater 3061 can be passed to a total waste management system 3062.

[0030] The effluent from the hydrotreating reactor 3002 is passed to a hydrotreating separation stage 3004. Amine 3005 can be injected into the effluent of the hydrotreating reactor before the effluent reaches the hydrotreating separation stage 3004. The hydrotreating separation stage produces wastewater 3006, recycle H.sub.2 3007, which can be recycled to the hydrotreating reactor 3002, C.sub.4-gasses 3008, and an hydrotreatment separation effluent 3009. The separation effluent 3009 can be passed to a cracking reactor, generally a catalytic hydrocracking reactor 3010, to which H.sub.2 3011 is passed. The cracking reaction can be run under typical hydrocracking reaction conditions.

[0031] The effluent from the cracking reactor 3010 can be injected with amine 3012 before being passed to a separation stage 3013. The separation stage 3013 produces wastewater 3014, recycle H.sub.2 2015, C.sub.4-gasses 3016, and a separation effluent 3017. The separation effluent 3017 can be passed to a fractionation stage 3018, and/or recycled back 3019 to the hydrotreating reactor 302, or recycled, at least partially, to the cacking reactor 3010. The fractionation stage can produce diesel 3020, jet fuel 3021, and naphtha 3022. The naphtha 3022 can be passed to a steam cracker 3023, along with C.sub.4-gases 3008 and 3016.

[0032] The following examples are provided to further illustrate the present process but is not meant to be limiting.

Examples 1-7

[0033] Pyrolysis oil hydrolysis by NaOH solution with different pHs at different temperatures, pressures, reaction times, and pyrolysis oil/NaOH solution ratios (examples #1-#7) are summarized in Table 1. The pyrolysis oil feed contains 268 ppm Cl, 28.5 ppm Si, 53.0 ppm Fe, and 10.6 ppm Zn.

[0034] The removals of Cl, Si, and metals are all higher than 90% at 280 C. (Examples 5-7). Within the boundaries of the conditions studied, higher temperature, higher initial pH of the NaOH metal solution, and longer reaction time favor higher percentage removal of Cl, Si, and metals at the same time.

[0035] Although Cl and Si were reported as aqueous product, no Fe and Zn were found in the same aqueous product. This indicates Fe and Zn compounds precipitated on the wall of the reactor during the process.

TABLE-US-00001 TABLE 1 Pyrolysis oil hydrolysis by NaOH solution at different temperatures, pressures, reaction times, and pyrolysis oil/NaOH solution ratios Example # 1 2 3 4 5 6 7 Temperature, C. 100 120 160 200 280 280 280 Time, min 180 180 15 15 15 30 180 Pressure, psig 130 180 890 1000 1006 1000 1000 pH of NaOH Solution 11 13 13 13 13.38 13 13 Oil/NaOH solution ratio, 30/30 30/30 30/30 30/30 30/15 30/30 30/30 mL/mL Final pH of Aqueous 4 12.29 12.47 12.3 11.35 11.13 10.7 Solution Cl removal wt % 49 75 72 91.4 97.7 98.3 98.2 Si removal wt % 0 48 49 58 91.8 91.0 96 Fe removal wt % 96 77 94 93 97.4 98.0 92 Zn removal wt % 100 89 89 90 100 100 91

[0036] This hydrolysis process should also remove P which is often detected in pyrolysis oil.

[0037] As used in this disclosure the word comprises or comprising is intended as an open-ended transition meaning the inclusion of the named elements, but not necessarily excluding other unnamed elements. The phrase consists essentially of or consisting essentially of is intended to mean the exclusion of other elements of any essential significance to the composition. The phrase consisting of or consists of is intended as a transition meaning the exclusion of all but the recited elements except for only minor traces of impurities.

[0038] As those skilled in the art will appreciate, numerous modifications and variations of the present invention are possible considering these teachings, and all such are contemplated hereby. For example, in addition to the embodiments described herein, the present invention contemplates and claims those inventions resulting from the combination of features of the invention cited herein and those of the cited prior art references which complement the features of the present invention. Similarly, it will be appreciated that any described material, feature, or article may be used in combination with any other material, feature, or article, and such combinations are considered within the scope of this invention.

[0039] All of the publications cited in this disclosure are incorporated by reference herein in their entireties for all purposes.