Circular economy for plastic waste to polypropylene and lubricating oil via refinery FCC and isomerization dewaxing units

Patent metadata

Field	Value
Publication number	US-12319877-B2
Application number	US-202418636100-A
Country	US
Kind code	B2
Filing date	Apr 15, 2024
Priority date	Dec 23, 2019
Publication date	Jun 3, 2025
Grant date	Jun 3, 2025

Abstract

A continuous process for converting waste plastic into recycle for polypropylene polymerization is provided. The process integrates refinery operations to provide an effective and efficient recycle process. The process comprises selecting waste plastics containing polyethylene and polypropylene and then 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 naphtha/diesel fraction, a heavy fraction, and char. The naphtha/diesel fraction is passed to a refinery FCC unit, from which is recovered a liquid petroleum gas C 3 olefin/paraffin mixture. The C 3 paraffins and C 3 olefins are separated into different fractions with a propane/propylene splitter. The C 3 olefin fraction is passed to a propylene polymerization reactor. The C 3 paraffin fraction is optionally passed to a dehydrogenation unit to produce additional propylene and then the resulting C 3 olefin is passed to a propylene polymerization reactor. The heavy fraction of pyrolyzed oil is passed to an isomerization dewaxing unit to produce a lubricating base oil.

First claim

What is claimed is:

1. A continuous process for converting waste plastic into recycle for polypropylene polymerization comprising:
(a) selecting waste plastics containing polyethylene and/or polypropylene wherein the selected plastics contain less than 5 wt % polyethylene terephthalate and polyvinyl chloride;
(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, a naphtha/diesel fraction, a heavy fraction, and char;
(d) passing the naphtha/diesel fraction to a refinery FCC unit along with virgin crude oil with volume flow of the naphtha/diesel fraction 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 from the FCC unit;
(f) separating the C 3 paraffin and C 3 olefin into different fractions;
(g) passing the C 3 paraffin to a dehydrogenation unit to produce C 3 olefin;
(h) passing C 3 olefin to a propylene polymerization reactor;
(i) passing the heavy fraction to an isomerization dewaxing unit to produce a base oil; and
(j) recovering a gasoline and heavy fraction from the FCC unit and further processing in the refinery to gasoline.

2. The process of claim 1 , wherein polypropylene is produced in the propylene polymerization reactor of (h).

3. The process of claim 1 , wherein the naphtha/diesel fraction of (d) is passed directly to a refinery FCC unit distillation section.

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

5. The process of claim 1 , wherein a heavy fraction is recovered from the FCC unit distillation column and further processed in the refinery to diesel or jet fuel.

6. The process of claim 1 , wherein gasoline and heavy fractions are produced by the FCC unit, with the amounts being increased due to the naphtha/diesel fraction passed to the FCC unit.

7. The process of claim 1 , wherein the amount of base oil produced by the isomerization dewaxing unit is increased due to the naphtha/diesel fraction passed to the FCC unit.

8. The process of claim 1 , wherein the heavy fraction in (i) is hydrotreated and then isomerized in the dewaxing unit.

9. The process of claim 1 , wherein the naphtha/diesel flow to the FCC unit comprises up to about 20 volume % of the total hydrocarbon flow to the FCC unit.

10. A process for converting waste plastic to chemicals useful in preparing polypropylene and lubricating oil comprising:
(a) selecting waste plastics containing polyethylene and/or polypropylene wherein the selected plastics contain less than 5 wt % polyethylene terephthalate and polyvinyl chloride;
(b) pyrolyzing the waste plastic and recovering a naphtha/diesel fraction and a heavy fraction;
(c) passing the naphtha/diesel fraction to a refinery FCC unit along with virgin crude oil with volume flow of the naphtha/diesel fraction comprising about 50 volume % or less of total hydrocarbon flow to the FCC unit; and
(d) passing the heavy fraction to an isomerization dewaxing unit.

Assignees

• Chevron Usa Inc

Inventors

• Timken Hye-Kyung

Classifications

• F26B25/003

  for articles · CPC title

• F26B11/022

  Arrangements of drives, bearings, supports · CPC title

• F26B5/08

  by centrifugal treatment · CPC title

• B68G15/00

  Auxiliary devices and tools specially for upholstery · CPC title

• C10G1/002 Primary

  in combination with oil conversion- or refining processes · CPC title