Circular economy for plastic waste to polyethylene via refinery FCC and alkylation units

Patent metadata

Field	Value
Publication number	US-11905466-B2
Application number	US-202218051001-A
Country	US
Kind code	B2
Filing date	Oct 30, 2022
Priority date	Dec 23, 2019
Publication date	Feb 20, 2024
Grant date	Feb 20, 2024

Abstract

Provided in one embodiment is a continuous process for converting waste plastic into recycle for polyethylene polymerization. The process comprises selecting waste plastics containing polyethylene and/or polypropylene, and passing the waste plastics through a pyrolysis reactor to thermally crack at least a portion of the polyolefin waste and produce a pyrolyzed effluent. The pyrolyzed effluent is separated into offgas, a pyrolysis oil and optionally wax comprising a naphtha/diesel and heavy fraction, and char. The pyrolysis oil and wax is passed to a refinery FCC unit from which a liquid petroleum gas C 3 -C 5 olefin/paraffin mixture fraction is recovered. The liquid petroleum gas C 3 -C 5 olefin/paraffin mixture fraction is passed to a refinery alkylation unit, with a propane and butane fraction recovered from the alkylation unit. The propane and butane fraction is then passed to a steam cracker for ethylene production. In another embodiment, a naphtha fraction (C 5 -C 8 ) is recovered from the alkylation unit and passed to the steam cracker. In another embodiment, a propane/propylene fraction (C 3 -C 3 ) is recovered from the FCC and passed to the steam cracker.

First claim

What is claimed is:

1. A continuous process for converting waste plastic into polyethylene recycle comprising:
(a) selecting waste plastics containing polyethylene and/or polypropylene;
(b) passing the waste plastics from (a) through a pyrolysis reactor to thermally crack at least a portion of the waste plastics and produce a pyrolyzed effluent;
(c) separating the pyrolyzed effluent into offgas, char and a pyrolysis oil comprising a naphtha/diesel fraction and a heavy fraction;
(d) passing the pyrolyzed oil from (c) to a refinery FCC unit along with virgin crude oil with volume flow of the pyrolysis oil comprising about 50 volume % or less of total hydrocarbon flow to the FCC unit;
(e) recovering a liquid petroleum gas C 3 olefin/paraffin mixture fraction from the FCC unit; and
(f) passing the C 3 olefin/paraffin fraction to a steam cracker for ethylene production.

2. The process of claim 1 , wherein a gasoline and heavy fraction are recovered from the refinery FCC unit.

3. The process of claim 1 , wherein ethylene produced in (f) is subsequently polymerized.

4. The process of claim 3 , wherein polyethylene products are prepared from the polymerized ethylene.

5. The process of claim 1 , wherein the waste plastics selected in (a) are from plastics classification group 2, 4, and/or 5.

6. The process of claim 1 , wherein the volume flow of pyrolysis flow to the refinery FCC unit is up to about 20 volume % of the total hydrocarbon flow to the FCC unit.

7. A process for converting waste plastic into useful chemicals comprising:
(a) selecting waste plastics containing polyethylene and/or polypropylene;
(b) pyrolyzing the waste plastics and recovering a pyrolysis oil and optionally wax comprising a naphtha/diesel fraction and a heavy fraction;
(c) passing the pyrolysis oil and wax from (b) to a refinery FCC unit along with virgin crude oil with volume flow of the pyrolysis oil comprising about 50 volume % or less of total hydrocarbon flow to the FCC unit;
(d) recovering a C 3 -C 5 olefin/paraffin mixture from the FCC unit; and
(e) passing the C 3 -C 5 olefin/paraffin mixture to a refinery alkylation unit.

8. The process of claim 7 , wherein a gasoline and heavy fraction are recovered from the refinery FCC unit.

9. The process of claim 7 , wherein an alkylate gasoline fraction is recovered from the refinery alkylation unit.

10. The process of claim 8 , wherein the gasoline fraction recovered from the refinery FCC unit is combined with an alkylate gasoline fraction recovered from the alkylation unit.

11. The process of claim 7 , wherein the waste plastics selected in (a) are from plastics classification group 2, 4, and/or 5.

12. The process of claim 7 , where the volume flow of pyrolysis oil to the refinery FCC unit is up to about 20 volume % of the total hydrocarbon flow to the FCC unit.

Assignees

• Chevron Usa Inc

Inventors

• Timken Hye-Kyung

Classifications

• C10G1/10 Primary

  from rubber or rubber waste · CPC title

• C07C2/76

  by condensation of hydrocarbons with partial elimination of hydrogen · CPC title

• C07C4/04

  Thermal processes {(C07C4/025 takes precedence)} · CPC title

• C08F10/02

  Ethene · CPC title

• C10B53/07

  {of solid raw materials consisting} of synthetic polymeric materials, e.g. tyres (recovery or working-up of waste materials of organic macromolecular compounds or compositions based thereon by dry-heat treatment for obtaining partially depolymerised materials C08J11/10; production of liquid hydrocarbon mixtures from rubber or rubber waste C10G1/10) · CPC title