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CN-121986150-A - Process for upgrading oil derived from pyrolysis of plastic waste

CN121986150ACN 121986150 ACN121986150 ACN 121986150ACN-121986150-A

Abstract

A process for purifying a crude pyrolysis oil comprising (i) treating the crude pyrolysis oil with a liquid non-hydrocarbon polar compound and (ii) separating the resulting product into a purified pyrolysis oil fraction having a reduced content of contaminants relative to the crude pyrolysis oil and a fraction comprising the non-hydrocarbon liquid polar compound, the fraction comprising the non-hydrocarbon liquid polar compound containing at least a portion of the contaminants present in the crude pyrolysis oil.

Inventors

  • D cloth Rita
  • F. Menikeli
  • N Alishendefeinidi

Assignees

  • 巴塞尔聚烯烃意大利有限公司

Dates

Publication Date
20260505
Application Date
20241106
Priority Date
20231106

Claims (15)

  1. 1. A process for producing and purifying a crude pyrolysis oil, the process comprising: a) Providing a molten plastic waste material comprising at least a polyolefin fraction in an amount of more than 70 wt% based on the total weight of the plastic waste material; b) Subjecting the molten product obtained in (a) to a temperature of 280 ℃ to 600 ℃ to obtain a depolymerized product; (c) Subjecting the depolymerization product to a condensation stage at a temperature in the range of from 10 ℃ to 250 ℃, preferably from 15 ℃ to 200 ℃, more preferably from 15 ℃ to 150 ℃, thereby obtaining the crude pyrolysis oil and a gaseous fraction as liquid fractions, the crude pyrolysis oil containing oxygenates and nitrogen-containing compounds as contaminants; (d) Contacting the crude pyrolysis oil with a non-hydrocarbon liquid polar compound selected from the group consisting of eutectic complexes having the formula [ A ] [ B ] x, wherein x ranges from 0.3 to 20, [ A ] is selected from the group consisting of metal salts, non-metal salts, and non-ionic Hydrogen Bond Acceptors (HBAs), and [ B ] is selected from the group consisting of metal salts, hydrated metal salts, and non-ionic hydrogen bond donor compounds (NIHBD), the eutectic complexes being immiscible with the crude pyrolysis oil, and (E) Recovering from the above steps (1) a purified pyrolysis oil fraction having reduced levels of nitrogen-containing compounds and oxygenates relative to the crude pyrolysis oil, and (2) a fraction comprising the liquid non-hydrocarbon liquid polar compounds, the fraction containing at least a portion of the contaminants present in the crude pyrolysis oil.
  2. 2. The process according to claim 1, wherein the liquid non-hydrocarbon polar compound is liquid at atmospheric pressure in the range of 10 ℃ to 250 ℃, more preferably 15 ℃ to 200 ℃.
  3. 3. A process according to any one of the preceding claims, wherein the eutectic compound is formed from at least two compounds and exhibits a single melting point that is lower than the melting point of each of the respective compounds.
  4. 4. The process of any one of the preceding claims, wherein [ a ] is a non-metal salt selected from the group consisting of non-metal salts formed from the following cations and anions : Wherein the R 1 to R 4 groups are independently selected from C 1 -C 20 alkyl or arylalkyl and C 6 -C 20 aryl or alkylaryl groups.
  5. 5. The process of any of the preceding claims, wherein [ B ] is selected from a nonionic hydrogen bond donor compound (NIHBD) selected from amides including cyclic amides, carboxylic acids and alcohols (NIHBD).
  6. 6. The process of claim 5, wherein [ B ] is selected from the following compounds:
  7. 7. The process according to any one of the preceding claims, wherein [ a ] is selected from the non-metal salts according to claim 4 and [ B ] is selected from the NIHBD compounds according to claim 6.
  8. 8. A process according to any one of the preceding claims, wherein in the eutectic compound the value of x ranges from 0.5 to 15, more preferably from 1 to 10, and in particular from 1 to 8.
  9. 9. The process of claim 7, wherein the eutectic compound is selected from the group consisting of:
  10. 10. The process according to any of the preceding claims, wherein step (d) is carried out at a temperature in the range of 20 to 250 ℃, more preferably 25 to 150 ℃, especially 25 to 100 ℃.
  11. 11. The process of any one of the preceding claims, wherein step (d) is performed as a plurality of steps, each of the plurality of steps being performed using one or more eutectic compounds.
  12. 12. A process according to any one of the preceding claims, wherein in step (d) the total mass ratio of eutectic compound to crude pyrolysis oil is such that at the end of the process the mass ratio of EC/Pyoil ranges from 0.01:1 to 100:1, preferably from 0.02:1 to 0.8:1, and more preferably from 0.02:1 to 0.5:1.
  13. 13. A process according to any one of the preceding claims, wherein in step (d) the total mass ratio of eutectic compound to crude pyrolysis oil is such that at the end of the process the mass ratio of EC/Pyoil ranges from 1:1 to 100:1, preferably from 2:1 to 80:1, and more preferably from 2:1 to 50:1.
  14. 14. The process according to any of the preceding claims, wherein the total contact time of step (d) ranges from 0.5 to 10 hours, more particularly from 1 to 6 hours.
  15. 15. The process of any one of the preceding claims, wherein step (e) is performed by removing the liquid non-hydrocarbon polar compound as a denser immiscible phase.

Description

Process for upgrading oil derived from pyrolysis of plastic waste Technical Field The present disclosure relates to a process for producing and purifying pyrolysis oil derived from plastic waste pyrolysis to obtain a upgraded pyrolysis oil having a reduced content of contaminants (such as nitrogen, oxygen, and halogens) based on its initial content in the unmodified pyrolysis oil. The disclosure also relates to the use of the pyrolysis oil, in particular as feedstock for a (steam) cracker. Background Plastics include a wide range of synthetic and semi-synthetic materials using polymers as their principal components. Their plasticity allows plastics to be molded, extruded or pressed into solid objects of various shapes. This adaptability combined with a wide range of other properties such as light weight, durability and low production costs has led to their widespread use. Over the last few decades, the production of plastics has increased dramatically. At the same time, an increase in the amount of plastic causes environmental problems, since most plastics are resistant to the natural degradation process. Thus, the material can last for centuries or longer, fill up landfills, and even appear as microplastic in the food chain. Accordingly, there is an increasing effort to improve the recovery of polymeric waste materials. Current recovery procedures rely primarily on mechanical recovery and chemical recovery. For mechanical recycling, the plastics are mechanically transformed without changing their chemical structure, so that they can be used to produce new articles. During chemical recycling, plastics are broken down into smaller pieces and their structure and chemical properties are altered so that they can be used as raw materials for different industries or as raw materials for manufacturing new polymer products. Chemical recovery typically involves the steps of collecting plastic waste, then heating the plastic waste to decompose the polymer, thereby obtaining smaller organic molecules, which can then be recycled in the petrochemical industry. Typically, the main effluent from the pyrolysis step is a liquid stream, also known as pyrolysis oil, which may be refined and used as fuel or subjected to a further steam cracking step to produce a fraction consisting of C 2-C4 olefins. In theory, polyolefins consisting of carbon and hydrogen only (such as polypropylene and polyethylene) are able to produce pyrolysis oils with low heterogeneous element content. However, plastic waste is typically mixed plastic waste composed of different types of polymers, including, for example, not only polyolefin, but also PET, polyamide (nylon), PU polymer, PVC, and the like. In addition, the polymers present in the plastic waste generally include heteroatom-containing additives, such as stabilizers and plasticizers, which have been introduced to improve the properties of the polymers. Such additives also often include nitrogen, halogen and sulfur containing compounds and heavy metals. In summary, unpurified (crude) pyrolysis oil from the chemical recovery of plastic waste contains relatively high amounts of undesirable contaminants such as oxygen, nitrogen, oxygen, halogens and metals. These materials are considered to be very detrimental to the steam cracking process because they can cause process problems, such as the formation of NOx materials and damage to process equipment. In addition, elements other than carbon and hydrogen may be detrimental during processing of the crude pyrolysis oil because they may deactivate or poison catalysts used in further processing of the pyrolysis oil. For example, during steam cracking, halogen-containing compounds may release hydrogen halide, thereby damaging the cracker by corrosion. Nitrogen-containing impurities may also poison downstream catalysts. In addition, they form explosive NOx when heated, which can lead to safety concerns. The oxygenates may produce compounds with an acidic/corrosive action, such as methanol, or form emulsions during the quench stage. For the above reasons, it is generally desirable to reduce or completely remove contaminants by the purification stage, thereby upgrading the crude pyrolysis oil for smooth use in the refinery process. EP2650345 A1 relates to the use of eutectic solvents for the removal of sulfur-containing species from liquid hydrocarbons (such as crude oil, mineral oil). Attempts to remove oxygen-containing and/or nitrogen-containing species are not described. The efficiency of sulfur compound removal is unsatisfactory (40%) when the EC/Pyoil mass ratio is 1:1. Jelena D Jovanovic et al also describe in paper (extractive desulfurization of cracked tire oils by hydrodynamic cavitation using eutectic solvents) (environmental science and pollution study (2021) 28:59268-59276) similar inefficiencies when DES/PO 1:1 or lower are used. The removal of oxygen, nitrogen and other contaminants by use of solid adsorbents is the most common technique in