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KR-20260068069-A - Method for disposing of liquid waste plastic

KR20260068069AKR 20260068069 AKR20260068069 AKR 20260068069AKR-20260068069-A

Abstract

The present invention relates to an improved method for treating liquefied waste plastic, comprising the steps of: providing a volume of liquefied waste plastic-based oil; heat-treating the volume of LWP-based oil; separating the generated heat-treated mixed volume into a first aqueous phase volume and a first oil phase volume; separating the first aqueous phase volume; adjusting the pH of the first aqueous phase volume to pH 9.0 or lower; and separating the pH-adjusted volume into at least a second aqueous phase volume and a second oil phase volume.

Inventors

  • 파시칼리오, 빌레
  • 카우피, 잉케리
  • 파사넨, 안티
  • 말리넨, 페카

Assignees

  • 네스테 오와이제이

Dates

Publication Date
20260513
Application Date
20240902
Priority Date
20230907

Claims (12)

  1. As a method for treating liquefied waste plastic (LWP), (i) a step of providing a volume of liquid waste plastic-based oil (A), (ii) a step of heat-treating (1) the volume of the above LWP-based oil (A) together with the volume of an alkaline aqueous medium (B) to provide a heat-treated mixed volume (C), (iii) A step of separating the heat-treated mixed volume (C) into at least two separate phase volumes (D; E), wherein one separated phase volume is a first aqueous phase volume (D) and the other separated phase volume is a first oil phase volume (E). (iv) A step of separating (2) the first aqueous phase volume (D) above, (v) a step of adding an acidic medium (F) to the first aqueous phase volume (D) to adjust the pH of the first aqueous phase volume (D) to pH 9.0 or lower (3) to form a pH-adjusted volume (G), and (vi) A step of separating the pH-adjusted volume (G) into at least two separate phase volumes (H; I) in a phase separation (4), wherein one separate phase volume is a second aqueous phase volume (I) and the other separate phase volume is a second oil phase volume (H). A method including
  2. In paragraph 1, The above acidic medium (F) comprises an organic acid and/or an inorganic acid, such as hydrochloric acid (HCl), nitric acid ( HNO₃ ), sulfuric acid ( H₂SO₄ ), phosphoric acid (H₃PO₄ ) , sulfamic acid ( H₃NSO₃ ), or a carboxylic acid.
  3. In paragraph 1 or 2, The above acidic medium (F) is a solution of acid, preferably an aqueous solution of acid, method.
  4. The method according to paragraph 3, wherein the acid is at least one selected from the group consisting of hydrochloric acid (HCl), nitric acid ( HNO₃ ), sulfuric acid ( H₂SO₄ ), phosphoric acid ( H₃PO₄ ), sulfamic acid ( H₃NSO₃ ), or carboxylic acid, and preferably at least sulfuric acid or hydrochloric acid.
  5. In paragraph 3 or 4, A method in which the above acid solution has a concentration in the range of 1 to 98 mass%, preferably 1 to 96 mass%, more preferably 50 to 70 mass%.
  6. In any one of paragraphs 1 through 5, The method in which the phase separation (2) of step (iii) is performed at a temperature in the range of 15°C to 200°C, preferably 40°C and 200°C, 50°C to 175°C, or 60°C and 150°C.
  7. In any one of paragraphs 1 through 6, A method in which the first oil phase volume (E) and/or the second oil phase volume (H) is further washed, preferably by water washing.
  8. In any one of paragraphs 1 through 7, A method in which, in step (iii), the pH of the first aqueous phase volume (D) is adjusted to a pH in the range of 1.5 to 9.0, preferably 2.0 to 9.0, more preferably 3.0 to 9.0, 4.0 to 8.7, 5.0 to 8.5, 6.0 to 8.3, or 7.0 to 8.0.
  9. In any one of paragraphs 1 through 8, The above alkaline aqueous medium (B) is an aqueous solution of a metal hydroxide, and the metal hydroxide is selected from the group consisting of alkali metal hydroxides and alkaline earth metal hydroxides.
  10. In any one of paragraphs 1 through 9, A method in which the water-oil ratio between the volume of the alkaline aqueous medium (B) and the volume of the liquefied waste plastic-based oil (A) in the heat treatment (1) of step (ii) is in the range of 0.1 to 1.4 by weight, preferably in the range of 0.2 to 1.0, e.g., 0.2 to 0.7.
  11. In any one of paragraphs 1 through 10, A method in which the heat treatment (1) of step (ii) is performed at a temperature in the range of 150°C to 450°C, preferably 180°C to 450°C, 200°C to 400°C, 210°C to 350°C, 220°C to 330°C, 240°C to 320°C, or 260°C to 300°C.
  12. In any one of paragraphs 1 through 11, A method further comprising the step of adjusting (5) the pH of the second aqueous phase volume (I) to a pH of 9.5 or higher, preferably 10.0 or higher, or 10.5 or higher, and preferably further comprising the step of evaporating (6) at least a portion of the second aqueous phase volume (M) after adjusting the pH (5) to provide at least one condensate (N) and at least one evaporation residue (P).

Description

Method for disposing of liquid waste plastic The present invention relates to an improvement in the treatment of liquefied waste plastics. More specifically, the present invention relates to an improved method for treating crude (untreated) liquefied waste plastics at high temperatures using an alkaline aqueous medium. Research has been conducted for years on purifying liquid waste plastic (LWP) into more valuable (pure) materials and converting liquid waste plastic (LWP) into more valuable materials. For example, FI 128848 B discloses a method comprising pre-treating liquefied waste plastic material at high temperature in the presence of an alkaline aqueous medium, followed by liquid-liquid separation and hydrogenation, as well as post-treatment to provide a steam cracking feed. FIG. 1 is a flowchart illustrating an embodiment of the method and system of the present invention. Figure 2 is a flowchart showing an example of wastewater treatment. Liquid waste plastics (LWP) (volume), such as the pyrolysis products of collected waste plastics (e.g., collected consumer plastics), contain large amounts of various contaminants harmful to downstream processes. These contaminants include halogens (e.g., chlorine and bromine) derived from halogenated plastics (e.g., PVC and PTFE) or flame retardants, sulfur derived from crosslinking agents of rubber polymers (e.g., end-of-life tires), and metal or metalloid (e.g., Si, Al) contaminants derived from composite materials and additives (e.g., films coated with metals or metal compounds, end-of-life tires, or plastic processing aids). These contaminants may exist in elemental form, ionic form, or as part of organic or inorganic compounds. These impurities must be removed before the LWP is subjected to further processing. The inventors of the present invention previously proposed a process involving phase separation following contact of (crude) LWP with an alkaline aqueous medium at high temperature (hereinafter also referred to as heat treatment (HT) processing). HT processing can also be called " reactive extraction ." That is, the inventors discovered that an appropriate combination of high pH in the alkaline aqueous medium and heat (HT processing process) causes the reaction of impurities (e.g., organically bonded) and provides advantages over simple "washing" or "neutralization treatment" of the LWP. In particular, the reactive extraction process is useful for removing at least some silicon compounds (organosilicon compounds are particularly problematic) and also removes chlorine compounds (organic and inorganic forms) and nitrogen-containing compounds. That is, reactive extraction can convert (organic) impurities into a water-soluble form and remove (separate) them along with the aqueous phase. The present invention is based on the aforementioned HT processing and provides an improved operation of the aqueous phase (hereinafter referred to as the "first aqueous phase volume") resulting from the HT processing after phase separation. Specifically, the inventors have surprisingly discovered that a significant amount of LWP is "lost" along with the aqueous phase, causing yield problems and wastewater handling problems. The inventors have surprisingly discovered that acidifying the first aqueous phase (volume) to a pH of 9.0 or lower allows for the separation of an additional amount (volume) of the oil phase in the subsequent (second) phase separation step. Consequently, the yield of the finally obtained LWP increases, and the purity of the aqueous phase increases (total organic carbon content decreases), thereby facilitating the operation. Based on these findings, the inventors have completed the invention. In the context of the present invention, liquefied waste plastic (LWP) refers to the product effluent from a liquefaction process comprising at least depolymerizing waste plastic. Thus, LWP is a material that can be obtained by depolymerizing waste plastic. LWP may also be referred to as polymer waste-based oil or liquefied waste plastic. Furthermore, whenever LWP (which is an abbreviation for "LWP-based oil") is mentioned, it naturally includes " volume of liquefied waste plastic-based oil ." This applies equally to the (volume) of an alkaline aqueous medium, the first/second aqueous phase (volume), the first/second oil phase (volume), the pH-adjusted (aqueous) volume, etc. Waste plastics may originate from any source, such as (recycled or collected) consumer plastics, (recycled or collected) industrial plastics, or (recycled or collected) end-of-life tires (ELT). In particular, the term waste plastics refers to organic polymer materials that are no longer suitable for use or have been discarded for other reasons. More specifically, waste plastics may refer to end-of-life tires (including rubber of natural origin), collected consumer plastics (consumer plastics refer to organic polymer materials in consumer products, even if they do not possess " plastic " characteri