Circular economy for plastic waste to polyethylene and lubricating oil via crude and isomerization dewaxing units
Provided is a continuous process for converting waste plastic into recycle for polyethylene polymerization. In one embodiment, 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 naphtha/diesel fraction, a heavy fraction, and char. The naphtha/diesel fraction is passed to a crude unit distillation column in a refinery where a straight run naphtha (C 5 -C 8 ) fraction or a propane/butane (C 3 -C 4 ) fraction is recovered. The straight run naphtha fraction (C 5 -C 8 ) or the propane/butane (C 3 -C 4 ) fraction is passed to a steam cracker for ethylene production. The heavy fraction from the pyrolysis unit can also be passed to an isomerization dewaxing unit to produce a base oil.
1. A continuous process for converting waste plastic into recycle for polyethylene polymerization 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, a naphtha/diesel fraction, a heavy fraction, and char;
(d) passing the naphtha/diesel fraction to a crude unit in a refinery 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 crude unit;
(e) recovering a straight run naphtha (C 5 -C 8 ) fraction from the crude unit;
(f) passing the straight run naphtha fraction (C 5 -C 8 ) to a steam cracker for ethylene production and subsequent ethylene polymerization;
(g) recovering heavy naphtha/diesel/gas oil from the crude unit and further processing in the refinery to clean gasoline; and
(h) passing the heavy fraction to an isomerization dewaxing unit to produce a base oil.
2. The process of claim 1 , wherein the naphtha/diesel fraction of (c) is passed directly to a refinery crude unit and contaminants are removed in a crude unit desalter.
3. The process of claim 1 , wherein contaminants are removed at the pyrolysis reactor.
4. The process of claim 1 , wherein consumer 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 heavy naphtha/diesel/gas oil recovered from the crude unit is also further processed in the refinery to diesel or jet fuel.
7. The process of claim 1 , wherein the heavy fraction in (h) is hydrotreated and then isomerized in the dewaxing unit.
8. The process of claim 1 , wherein the naphtha/diesel flow comprises up to 20 volume %.
9. The process of claim 1 , wherein the selected waste plastics contain less than 5 wt % polyethylene terephthalate and polyvinyl chloride.
10. A continuous process for converting waste plastic into recycle for polyethylene polymerization 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, a naphtha/diesel fraction, a heavy fraction, and char;
(d) passing the naphtha/diesel fraction to a crude unit in a refinery 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 crude unit;
(e) recovering a propane and butane (C 3 -C 4 ) fraction from the crude unit;
(f) passing the (C 3 -C 4 ) fraction to a steam cracker for ethylene production and subsequent ethylene polymerization;
(g) recovering heavy naphtha/diesel/gas oil from the crude unit and further processing in the refinery to clean gasoline, and
(h) passing the heavy fraction to an isomerization dewaxing unit to produce a base oil.
11. The process of claim 10 , wherein the naphtha/diesel fraction of (c) is passed directly to a refinery crude unit and contaminants are removed in a crude unit desalter.
12. The process of claim 10 , wherein contaminants are removed at the pyrolysis reactor.
13. The process of claim 10 , wherein consumer polyethylene products are prepared from the polymerized ethylene.
14. The process of claim 10 , wherein the waste plastics selected in (a) are from plastics classification group 2, 4, and/or 5.
15. The process of claim 10 , wherein the selected waste plastics contain less than 5 wt % polyethylene terephthalate and polyvinyl chloride.
16. The process of claim 10 , wherein the heavy naphtha/diesel gas oil recovered from the crude unit is also processed in the refinery to diesel or jet fuel.
17. The process of claim 10 , wherein the heavy fraction in (g) is hydrotreated and then isomerized in the dewaxing unit.
18. The process of claim 10 , wherein the naphtha/diesel flow comprises up to 20 volume %.
19. A process for converting waste plastic into chemicals useful in preparing polyethylene and lubricating oil comprising:
(a) selecting waste plastics containing polyethylene and/or polypropylene;
(b) pyrolyzing the waste plastics and recovering a naphtha/diesel fraction and a heavy fraction;
(c) passing the naphtha/diesel fraction to a crude unit in a refinery 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 crude unit; and
(d) passing the heavy fraction to an isomerization dewaxing unit.