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EP-4737538-A1 - METHOD FOR REFINING PYROLYSIS OIL

EP4737538A1EP 4737538 A1EP4737538 A1EP 4737538A1EP-4737538-A1

Abstract

Provided is a method for refining a pyrolysis oil including: supplying a waste plastic raw material to a pyrolysis reactor to perform pyrolysis, and discharging a gaseous stream produced by the pyrolysis upwards; supplying an upper discharge stream from the pyrolysis reactor to a distillation column, and discharging a pyrolysis oil stream having a decreased content of a heavy oil fraction from the distillation column; and supplying the pyrolysis oil stream to an anion exchange resin column to bring the stream into contact with the anion exchange resin and remove impurities included in the pyrolysis oil stream.

Inventors

  • NA, SU JIN
  • AN, JI WON
  • LEE, SANG BEOM

Assignees

  • LG Chem, Ltd.

Dates

Publication Date
20260506
Application Date
20250629

Claims (12)

  1. A method for refining a pyrolysis oil, the method comprising: supplying a waste plastic raw material to a pyrolysis reactor to perform pyrolysis, and discharging a gaseous stream produced by the pyrolysis upwards; supplying an upper discharge stream from the pyrolysis reactor to a distillation column, and discharging a pyrolysis oil stream having a decreased content of a heavy oil fraction from the distillation column; and supplying the pyrolysis oil stream to an anion exchange resin column to bring the stream into contact with the anion exchange resin and remove impurities included in the pyrolysis oil stream.
  2. The method for refining a pyrolysis oil of claim 1, wherein the waste plastic raw material is a mixture including one or more selected from the group consisting of polyethylene (PE) and polypropylene (PP).
  3. The method for refining a pyrolysis oil of claim 1, wherein an operating temperature of the pyrolysis reactor is 400°C to 500°C.
  4. The method for refining a pyrolysis oil of claim 1, wherein an upper operating temperature of the distillation column is 30°C to 50°C.
  5. The method for refining a pyrolysis oil of claim 1, wherein in the distillation column, the upper discharge stream from the pyrolysis reactor is separated into a stream including a C20+ heavy oil fraction, a stream including a C1 to C4 light oil fraction, and a stream including a C4 to C25 middle oil fraction depending on their boiling points and discharged, and the pyrolysis oil stream is the stream including the middle oil fraction.
  6. The method for refining a pyrolysis oil of claim 1, wherein a content of the heavy oil fraction included in the pyrolysis oil stream is less than 40 wt%.
  7. The method for refining a pyrolysis oil of claim 1, wherein the pyrolysis oil stream is cooled to 40°C or lower through a heat exchanger and then supplied to the anion exchange resin column.
  8. The method for refining a pyrolysis oil of claim 1, wherein the anion exchange resin column is operated at a temperature of 20°C or higher and a pressure of 0 barg or more.
  9. The method for refining a pyrolysis oil of claim 1, wherein the anion exchange resin filling the inside of the anion exchange resin column is a resin including any one or more exchange groups selected from the group consisting of a primary amine group, a secondary amine group, a tertiary amine group, and a quaternary ammonium group.
  10. The method for refining a pyrolysis oil of claim 9, wherein the anion exchange resin is any one or more resins selected from styrene-based resins and acryl-based resins.
  11. The method for refining a pyrolysis oil of claim 1, wherein a weight ratio between the anion exchange resin and the pyrolysis oil in the anion exchange resin column is 1:1 or more.
  12. The method for refining a pyrolysis oil of claim 1, wherein the impurities include one or more selected from the group consisting of nitrogen (N), chlorine (Cl), and silicon (Si) .

Description

[Technical Field] CROSS-REFERENCE TO RELATED APPLICATIONS The present application claims the benefit of priority to Korean Patent Application No. 10-2024-0124333, filed on September 11, 2024, the entire contents of which are incorporated herein as a part of the specification. Technical Field The present invention relates to a method for refining a pyrolysis oil, and more particularly, to a method for removing impurities included in a pyrolysis oil produced from waste plastics. [Background Art] Waste plastics, which are manufactured using petroleum as a raw material, have low recyclability and are mostly disposed of as garbage. Since it takes a long time to decompose these wastes in natural conditions, soil is polluted, and serious environmental pollution is caused. As a method for recycling the waste plastics, waste plastics are pyrolyzed to be converted into an available oil fraction, and the oil fraction produced therefrom is referred to as a waste plastic pyrolysis oil. However, since a pyrolysis oil obtained by pyrolyzing waste plastics has a high content of impurities such as nitrogen (N), chlorine (Cl), and silicon (Si) as compared with an oil fraction manufactured from crude oil by a common method, it may not be directly used as a high value-added fuel such as gasoline and diesel oil and should go through a post-treatment process. As a conventional post-treatment process, a process of hydrogenating a waste plastic pyrolysis oil in the presence of a hydrogenation catalyst to remove chlorine, nitrogen, or other metal impurities is being performed, but in this process, an excessive amount of HCl is produced by a high content of chlorine included in the waste plastic pyrolysis oil, and the HCl causes problems such as equipment corrosion and abnormal reactions and deterioration of product properties. In particular, HCl and a nitrogen compound are reacted to produce an ammonium salt (NH4Cl), which causes corrosion of a reactor to decrease durability and also causes various process problems such as pressure differential occurrence, reactor clogging, and process efficiency reduction. Meanwhile, a waste plastic pyrolysis oil is a mixture of hydrocarbon oil fractions having various boiling points and various molecular weight distributions, and since the composition and the reaction activity of impurities in the pyrolysis oil vary depending on the boiling point and the molecular weight distribution properties of the hydrocarbon mixture, the waste plastic pyrolysis oil may not be directly used in the petrochemical industry or field, and a high value addition process such as a separation process by boiling point or a lightening process is performed. Among the hydrocarbon oil fraction mixtures, olefins, in particular, light olefins such as ethylene and propylene are widely used in the petrochemical industry. As a lightening process for high value addition of the waste plastic pyrolysis oil, a hydrogenation decomposition process is being performed, but since the waste plastic pyrolysis oil has an excessive amount of impurities as compared with crude oil, natural gas, a naphtha fraction, or the like, reaction activity is significantly reduced by the impurities in the hydrogenation decomposition process, a hydrogenation decomposition process should be separately performed apart from a hydrogenation treatment process, and thus, process efficiency is also lowered. As such, since a pyrolysis oil including many impurities has limitations in its use, in order to use the pyrolysis oil as a petrochemical raw material, impurities in the pyrolysis oil should be removed, and a technology for removing the impurities in the pyrolysis oil without using a post-treatment process such as hydrogenation treatment or hydrogenation decomposition is needed. [Disclosure] [Technical Problem] In order to solve the problems mentioned in the Background Art, an object of the present invention is to provide a method for removing impurities in a pyrolysis oil. That is, the present invention allows flowability even under room temperature and normal pressure conditions by removing a heavy oil fraction in the pyrolysis oil through a distillation column, so that impurities in the pyrolysis oil may be then continuously removed with a small energy usage using an anion exchange resin column. However, the object to be solved in the present application is not limited to the object mentioned above, and other objects which are not mentioned may be clearly understood by a person skilled in the art from the following descriptions. [Technical Solution] In one general aspect, a method for refining a pyrolysis oil includes: supplying a waste plastic raw material to a pyrolysis reactor to perform pyrolysis, and discharging a gaseous stream produced by the pyrolysis upwards; supplying an upper discharge stream from the pyrolysis reactor to a distillation column, and discharging a pyrolysis oil stream having a decreased content of a heavy oil fraction from the dis