CN-122029256-A - Method for refining pyrolysis oil

Abstract

A method of refining pyrolysis oil includes feeding a waste plastic feedstock to a pyrolysis reactor to perform pyrolysis and discharging a gaseous stream generated by the pyrolysis upward, feeding an upper discharge stream from the pyrolysis reactor to a distillation column and discharging a pyrolysis oil stream having a reduced heavy oil fraction content from the distillation column, and feeding the pyrolysis oil stream to an anion exchange resin column to contact the stream with anion exchange resin and remove impurities contained in the pyrolysis oil stream.

Inventors

• LUO XIUZHEN
• An Chiyuan
• LI XIANGFAN

Assignees

• 株式会社LG化学

Dates

Publication Date

20260512

Application Date

20250629

Priority Date

20240911

Claims (12)

1. 1. A method of refining pyrolysis oil, the method comprising: Feeding waste plastic raw materials into a pyrolysis reactor for pyrolysis, and discharging a gaseous material flow generated by the pyrolysis upwards; Supplying an upper effluent stream from the pyrolysis reactor to a distillation column and discharging a pyrolysis oil stream from the distillation column having a reduced heavy oil fraction content, and The pyrolysis oil stream is supplied to an anion exchange resin column to contact the stream with anion exchange resin and remove impurities contained in the pyrolysis oil stream.
2. 2. The method of refining pyrolysis oil of claim 1, wherein the waste plastic feedstock is a mixture comprising one or more selected from Polyethylene (PE) and polypropylene (PP).
3. 3. The method of refining pyrolysis oil of claim 1, wherein the pyrolysis reactor is operated at a temperature of 400 ℃ to 500 ℃.
4. 4. The method of refining pyrolysis oil of claim 1, wherein an upper operating temperature of the distillation column is from 30 ℃ to 50 ℃.
5. 5. The method for refining pyrolysis oil according to claim 1, wherein in the distillation column, the upper discharge stream from the pyrolysis reactor is separated into a stream containing c20+ heavy oil fraction, a stream containing C1 to C4 light oil fraction, and a stream containing C4 to C25 middle oil fraction according to boiling points and discharged, and The pyrolysis oil stream is a stream comprising the medium oil fraction.
6. 6. The method of refining pyrolysis oil of claim 1, wherein the pyrolysis oil stream comprises less than 40 wt% heavy oil fraction.
7. 7. The method of refining pyrolysis oil of claim 1, wherein the pyrolysis oil stream is cooled to below 40 ℃ by a heat exchanger and then supplied to the anion exchange resin column.
8. 8. The method of refining pyrolysis oil of claim 1, wherein the anion exchange resin column is operated at a temperature above 20 ℃ and a pressure above 0 barg.
9. 9. The method for refining pyrolysis oil according to claim 1, wherein the anion exchange resin filled inside the anion exchange resin column is a resin containing any one or more exchange groups selected from a primary amine group, a secondary amine group, a tertiary amine group and a quaternary ammonium group.
10. 10. The method for refining pyrolysis oil according to claim 9, wherein the anion exchange resin is any one or more resins selected from a styrene-based resin and an acrylic-based resin.
11. 11. The method of refining pyrolysis oil of claim 1, wherein a weight ratio of the anion exchange resin to the pyrolysis oil in the anion exchange resin column is 1:1 or more.
12. 12. The method of refining pyrolysis oil of claim 1, wherein the impurities comprise one or more selected from the group consisting of nitrogen (N), chlorine (Cl), and silicon (Si).

Description

Method for refining pyrolysis oil Cross Reference to Related Applications The present application claims priority from korean patent application No. 10-2024-0124033, filed on day 11, 9, 2024, which is incorporated herein in its entirety as part of the specification. Technical Field The present invention relates to a method of refining pyrolysis oil, and more particularly, to a method for removing impurities contained in pyrolysis oil manufactured from waste plastics. Background Waste plastics produced from petroleum are low in recoverability and are mostly treated as garbage. Since these wastes take a long time to decompose under natural conditions, soil is contaminated, causing serious environmental pollution. As a recycling method of waste plastics, waste plastics are pyrolyzed to be converted into usable oil fractions, and the oil fractions thus produced are called waste plastics pyrolysis oil. However, pyrolysis oil obtained by pyrolysis of waste plastics is high in nitrogen (N), chlorine (Cl), silicon (Si) and other impurities as compared with oil fractions produced from crude oil by a usual method, and therefore cannot be used as it is as a high value-added fuel such as gasoline and diesel oil, and a post-treatment process is sometimes performed. 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 performed, but in this process, HCl is generated excessively due to a high chlorine content contained in the waste plastic pyrolysis oil, and thus, problems such as equipment corrosion, abnormal reaction, and deterioration of product performance are caused by HCl. In particular, the reaction of HCl and nitrogen compounds produces ammonium salts (NH 4 Cl), which lead to corrosion of the reactor and reduced durability, and also to various process problems such as the generation of pressure differences, reactor plugging and reduced process efficiency. Meanwhile, 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 reactivity of impurities in the pyrolysis oil vary with the boiling point and molecular weight distribution properties of the hydrocarbon mixture, the waste plastic pyrolysis oil cannot be directly used in petrochemical industry or field, but is subjected to high added value processes such as a separation process or a lightening process by boiling points. In hydrocarbon oil fraction mixtures, olefins, particularly light olefins such as ethylene and propylene, are widely used in the petrochemical industry. For the purpose of high added value of waste plastic pyrolysis oil, a process of lightening is being performed as a hydrocracking process, but the waste plastic pyrolysis oil has more impurities than crude oil, natural gas, naphtha fraction, etc., and thus, the reactivity is significantly reduced due to impurities in the hydrocracking process, and thus, it is necessary to perform a further hydrocracking process in addition to the hydrotreating process, and thus, the process efficiency is also reduced. Accordingly, since pyrolysis oil containing many impurities has a limit in its use, in order to use the pyrolysis oil as a petrochemical raw material, the impurities in the pyrolysis oil should be removed, and a technique for removing the impurities in the pyrolysis oil without using a post-treatment process such as hydrotreating or hydrocracking is required. Disclosure of Invention 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 pyrolysis oil. That is, the present invention removes heavy oil fractions in pyrolysis oil through a distillation column, allowing fluidity even under room temperature and normal pressure conditions, so that impurities in pyrolysis oil can be subsequently removed continuously with a small energy consumption using an anion exchange resin column. However, the object to be achieved by the present application is not limited to the above object, and other objects not mentioned will be clearly understood by those skilled in the art from the following description. Technical proposal In one general aspect, a method of refining pyrolysis oil includes feeding a waste plastic feedstock to a pyrolysis reactor for pyrolysis and discharging a gaseous stream produced by pyrolysis upward, feeding an upper discharge stream from the pyrolysis reactor to a distillation column and discharging a pyrolysis oil stream having a reduced heavy oil fraction content from the distillation column, and feeding the pyrolysis oil stream to an anion exchange resin column to contact the stream with anion exchange resin and remove impurities contained in the pyrolysis oil stream. Advantageous effects According to the method for ref