Conversion of waste plastic to propylene and cumene
A process for producing cumene comprising converting plastics to hydrocarbon liquid and pyrolysis gas; feeding hydrocarbon liquid to hydroprocessor to yield hydrocarbon product and first gas stream; feeding hydrocarbon product to reforming unit to produce reforming product, second gas stream, and hydrogen; separating reforming product into non-aromatics recycle stream and second aromatics stream (C 6 + aromatics); recycling non-aromatics recycle stream to reforming unit; separating second aromatics stream into benzene, C 7 , C 8 , C 9 , C 10 , and C 11 + aromatics; contacting C 7 , C 9 , and/or C 10 aromatics with a disproportionation&transalkylation catalyst/H2 to yield benzene&xylenes; conveying C 11 + aromatics to hydroprocessor; introducing pyrolysis gas, first and/or second gas stream to first separator to produce first propylene stream, first C 2 &C 4 unsaturated stream, and saturated gas (H 2 and C 1-4 saturated hydrocarbons); introducing first C 2 &C 4 unsaturated stream to metathesis reactor to produce second propylene stream; and feeding benzene, and first and/or second propylene stream to alkylation unit to produce cumene.
1. A process for producing cumene comprising:
(a) converting a plastic waste to a hydrocarbon liquid stream and a pyrolysis gas stream in a pyrolysis unit;
(b) contacting at least a portion of the hydrocarbon liquid stream with a hydroprocessing catalyst in the presence of hydrogen in a hydroprocessing unit to yield a hydrocarbon product and a first gas stream, wherein the hydrocarbon product comprises C 5 + hydrocarbons;
(c) feeding at least a portion of the hydrocarbon product to a reforming unit to produce a reforming unit product, a second gas stream, and a hydrogen stream, wherein the reforming unit comprises a reforming catalyst, and wherein an amount of C 6 to C 8 aromatic hydrocarbons in the reforming unit product is greater than an amount of C 6 to C 8 aromatic hydrocarbons in the hydrocarbon product;
(d) introducing at least a portion of the reforming unit product to a second aromatics separating unit to produce a non-aromatics recycle stream and a second aromatics stream, wherein the second aromatics stream comprises C 6 + aromatic hydrocarbons;
(e) recycling at least a portion of the non-aromatics recycle stream to the reforming unit;
(f) introducing at least a portion of the second aromatics stream to a third aromatics separating unit to produce a benzene stream, a C 7 aromatics stream, a C 8 aromatics stream, a C 9 aromatics stream, a C 10 aromatics stream, and a C 11 + aromatics stream, wherein the benzene stream comprises benzene, wherein the C 7 aromatics stream comprises toluene, and wherein the C 8 aromatics stream comprises xylenes and ethylbenzene;
(g) contacting at least a portion of the C 7 aromatics stream, at least a portion of the C 9 aromatics stream, at least a portion of the C 10 aromatics stream, or combinations thereof with a disproportionation and transalkylation catalyst in the presence of hydrogen in a disproportionation and transalkylation unit to yield a third aromatics stream, wherein the third aromatics stream comprises benzene and xylenes;
(h) conveying at least a portion of the C 11 + aromatics stream to the hydroprocessing unit;
(i) introducing at least a portion of the pyrolysis gas stream, at least a portion of the first gas stream, at least a portion of the second gas stream, or combinations thereof to a first separating unit to produce a first propylene stream, a first C 2 and C 4 unsaturated stream, and a saturated gas stream, wherein the first propylene stream comprises propylene, wherein the first C 2 and C 4 unsaturated stream comprises ethylene and butylenes, and wherein the saturated gas stream comprises hydrogen and C 1 to C 4 saturated hydrocarbons;
(j) feeding at least a portion of the first C 2 and C 4 unsaturated stream to a metathesis reactor to produce a second propylene stream, wherein the metathesis reactor comprises a metathesis catalyst, and wherein the second propylene stream comprises propylene; and
(k) feeding at least a portion of the benzene stream, and at least a portion of the first propylene stream and/or at least a portion of the second propylene stream to an alkylation unit to produce cumene, wherein the alkylation unit comprises an alkylation catalyst.
2. The process of claim 1 , further comprising recycling at least a portion of the non-aromatics recycle stream to the pyrolysis unit.
3. The process of claim 1 , further comprising the step of introducing at least a portion of the hydrocarbon product to a first aromatics separating unit to produce a saturated hydrocarbons stream and a first aromatics stream, wherein the saturated hydrocarbons stream comprises C 5 + saturated hydrocarbons, and wherein the first aromatics stream comprises C 6 + aromatic hydrocarbons.
4. The process of claim 3 , further comprising (i) conveying at least a portion of the saturated hydrocarbons stream to the reforming unit and/or (ii) conveying at least a portion of the first aromatics stream to the third aromatics separating unit.
5. The process of claim 1 , wherein an overall cumene yield is equal to or greater than about 25 wt. %.
6. The process of claim 1 , further comprising the step of recovering at least a portion of the benzene from the third aromatics stream.
7. The process of claim 6 , wherein an overall benzene yield is equal to or greater than about 16 wt. %.
8. The process of claim 1 , further comprising the step of recovering at least a portion of the xylenes from the C 8 aromatics stream.
9. The process of claim 8 , wherein an overall xylenes yield is equal to or greater than about 16 wt. %.
10. The process of claim 1 , wherein the step (a) of converting a plastic waste to a hydrocarbon liquid stream and a pyrolysis gas stream in a pyrolysis unit is performed at a temperature of less than about 450° C.
11. The process of claim 1 , wherein the pyrolysis unit is a low severity pyrolysis unit.
12. The process of claim 1 , wherein the hydrocarbon product comprises equal to or greater than about 95 wt. % C 8− hydrocarbons, based on the total weight of the hydrocarbon product.
13. A process for producing cumene comprising:
(a) converting a first plastic waste to a first hydrocarbon liquid stream and a first pyrolysis gas stream in a first pyrolysis unit;
(b) optionally contacting at least a portion of the first hydrocarbon liquid stream with a first hydroprocessing catalyst in the presence of hydrogen in a first hydroprocessing unit to yield a first hydrocarbon product and a first C 1-4 gas stream, wherein the first hydrocarbon product comprises C 5 + hydrocarbons;
(c) recycling at least a portion of the first hydrocarbon liquid stream and/or at least a portion of the first hydrocarbon product to the first pyrolysis unit;
(d) converting a second plastic waste to a second hydrocarbon liquid stream and a second pyrolysis gas stream in a second pyrolysis unit;
(e) contacting at least a portion of the second hydrocarbon liquid stream with a second hydroprocessing catalyst in the presence of hydrogen in a second hydroprocessing unit to yield a second hydrocarbon product and a second C 1-4 gas stream, wherein the second hydrocarbon product comprises C 5 to C 8 hydrocarbons, and wherein the first hydroprocessing catalyst and the second hydroprocessing catalyst are the same or different;
(f) feeding at least a portion of the second hydrocarbon product to a reforming unit to produce a reforming unit product, a third C 1-4 gas stream, and a hydrogen stream, wherein the reforming unit comprises a reforming catalyst, and wherein an amount of C 6 to C 8 aromatic hydrocarbons in the reforming unit product is greater than an amount of C 6 to C 8 aromatic hydrocarbons in the second hydrocarbon product;
(g) introducing at least a portion of the reforming unit product to a second aromatics separating unit to produce a non-aromatics recycle stream and a second aromatics stream, wherein the second aromatics stream comprises C 6 + aromatic hydrocarbons;
(h) recycling at least a portion of the non-aromatics recycle stream to the reforming unit;
(i) introducing at least a portion of the second aromatics stream to a third aromatics separating unit to produce a benzene stream, a C 7 aromatics stream, a C 8 aromatics stream, a C 9 aromatics stream, a C 10 aromatics stream, and a C 11 + aromatics stream, wherein the benzene stream comprises benzene, wherein the C 7 aromatics stream comprises toluene, and wherein the C 8 aromatics stream comprises xylenes and ethylbenzene;
(j) contacting at least a portion of the C 7 aromatics stream, at least a portion of the C 9 aromatics stream, at least a portion of the C 10 aromatics stream, or combinations thereof with a disproportionation and transalkylation catalyst in the presence of hydrogen in a disproportionation and transalkylation unit to yield a third aromatics stream, wherein the third aromatics stream comprises benzene and xylenes;
(k) conveying at least a portion of the C 11 + aromatics stream to the first hydroprocessing unit and/or the second hydroprocessing unit;
(l) introducing at least a portion of the first pyrolysis gas stream, at least a portion of the second pyrolysis gas stream, at least a portion of the first C 1-4 gas stream, at least a portion of the second C 1-4 gas stream, at least a portion of the third C 1-4 gas stream, or combinations thereof to a first separating unit to produce a first propylene stream, a first C 2 and C 4 unsaturated stream, and a saturated gas stream, wherein the first propylene stream comprises propylene, wherein the first C 2 and C 4 unsaturated stream comprises ethylene and butylenes, and wherein the saturated gas stream comprises hydrogen and C 1 to C 4 saturated hydrocarbons;
(m) feeding at least a portion of the first C 2 and C 4 unsaturated stream to a metathesis reactor to produce a second propylene stream, wherein the metathesis reactor comprises a metathesis catalyst, and wherein the second propylene stream comprises propylene; and
(n) feeding at least a portion of the benzene stream, and at least a portion of the first propylene stream and/or at least a portion of the second propylene stream to an alkylation unit to produce cumene, wherein the alkylation unit comprises an alkylation catalyst.
14. The process of claim 13 , wherein the step (a) of converting a first plastic waste to a first hydrocarbon liquid stream and a first pyrolysis gas stream in a first pyrolysis unit is performed at a temperature of equal to or greater than about 450° C.
15. The process of claim 13 , wherein the step (d) of converting a second plastic waste to a second hydrocarbon liquid stream and a second pyrolysis gas stream in a second pyrolysis unit is performed at a temperature of less than about 450° C.
16. The process of claim 13 , wherein an overall cumene yield is equal to or greater than about 27 wt. %.
17. The process of claim 13 , further comprising the step of recovering at least a portion of the benzene from the third aromatics stream.
18. The process of claim 17 , wherein an overall benzene yield is equal to or greater than about 18 wt. %.
19. The process of claim 13 , further comprising the step of recovering at least a portion of the xylenes from the C 8 aromatics stream.
20. The process of claim 19 , wherein an overall xylenes yield is equal to or greater than about 18 wt. %.