Chemical recycling of solvolysis terephthalyl column bottoms coproduct streams
Described are methods for processing waste plastic that comprise withdrawing a terephthalyl column bottoms coproduct stream from a solvolysis facility used to process PET-containing waste plastic and introducing at least a portion of the coproduct stream into at least one of the following: (i) a partial oxidation (POX) gasification facility; (ii) a pyrolysis facility; (iii) a cracker facility; and (iv) an energy generation/energy production facility; and solvolysis coproduct compositions formed within a solvolysis facility for processing polyester terephthalate-containing waste plastic.
1 . A method for processing waste plastic, said method comprising:
(a) withdrawing a terephthalyl column bottoms coproduct stream from a solvolysis facility used to process PET-containing waste plastic; and
(b) introducing at least a portion of said coproduct stream into at least one of the following: (i) a partial oxidation (POX) gasification facility; (ii) a pyrolysis facility; (iii) a cracker facility; and (iv) an energy generation/energy production facility.
2 . The method of claim 1 , wherein said withdrawing is performed in a continuous manner.
3 . The method of claim 1 , wherein said solvolysis facility produces a principal terephthalyl and wherein said terephthalyl column bottoms coproduct stream has a mid-range boiling point higher than the boiling point of said principal terephthalyl.
4 . The method of claim 1 , further comprising introducing another coproduct stream from said solvolysis facility into at least one of the following: (i) a partial oxidation (POX) facility; (ii) a pyrolysis facility; (iii) a solidification facility; (iv) a cracker facility; and (v) an energy generation/energy production facility.
5 . The method of claim 4 , wherein said terephthalyl column bottoms coproduct stream and said another coproduct stream are introduced into different ones of (i) through (v).
6 . The method of claim 4 , wherein said terephthalyl column bottoms coproduct stream and said another coproduct stream are introduced into the same ones of (i) through (v).
7 . The method of claim 1 , wherein at least a portion of said terephthalyl column bottoms coproduct stream is introduced into a POX gasification facility.
8 . The method of claim 7 , wherein said POX gasification facility includes a liquid-fed gasifier.
9 . The method of claim 7 , wherein said POX gasification facility includes a solid-fed gasifier.
10 . A method for processing waste plastic, said method comprising:
(a) separating a stream of mixed plastic waste (MPW) into a polyethylene terephthalate-enriched (PET-enriched) stream and a polyolefin-enriched stream (PO-enriched) stream;
(b) subjecting at least a portion of said PET-enriched stream to solvolysis in a solvolysis facility to form a principal glycol product, a principal terephthalyl product, and at least one coproduct stream, wherein said coproduct stream comprises a terephthalyl column bottoms coproduct stream; and
(c) introducing at least a portion of said terephthalyl column bottoms coproduct stream from said solvolysis facility into at least one of the following: (i) a partial oxidation (POX) gasification facility; (ii) a pyrolysis facility; (iii) a solidification facility; (iv) a cracker facility; and (v) an energy generation/energy production facility.
11 . The method of claim 10 , wherein said PET-enriched stream comprises at least 60 weight percent PET and not more than 40 weight percent of polyolefins, based on the total weight of the PET-enriched stream, wherein said PO-enriched stream comprises at least 60 weight percent polyolefins and not more than 40 weight percent of PET, based on the total weight of the PO-enriched stream, and wherein said PET-enriched stream comprises not more than 10 weight percent of halogens, based on the total weight of the PET-enriched stream.
12 . The method of claim 10 , wherein said terephthalyl column bottoms coproduct stream has a temperature in the range of from 130 to 290° C. when withdrawn from said solvolysis facility.
13 . The method of claim 10 , wherein said introducing is performed in a batch manner.
14 . The method of claim 10 , further comprising introducing at least a portion of said PO-enriched stream into at least one of the following: (i) a partial oxidation (POX) gasification facility; (ii) a pyrolysis facility; (iii) a solidification facility; and (iv) an energy generation/energy production facility.
15 . The method of claim 10 , wherein said solvolysis facility comprises a methanolysis facility.
16 . The method of claim 10 , further comprising introducing said terephthalyl column bottoms coproduct stream into at least two of facilities (i) through (v).
17 . A solvolysis coproduct composition formed within a solvolysis facility for processing polyester terephthalate-containing waste plastic to form a principal glycol product and a principal terephthalyl product using a solvent, said composition comprising:
at least 70 weight percent of oligomers comprising polyester moieties; and
at least 1 part per billion (ppb) by weight and not more than 25 weight percent of substituted terephthalyl components, based on the total weight of the composition,
wherein said composition has a mid-range boiling point higher than the boiling point of said terephthalyl.
18 . The composition of claim 7 wherein said oligomers comprise moieties of at least one ester other than dimethyl terephthalate, at least one carboxylic acid other than terephthalic acid, and/or at least one glycol other than ethylene glycol.
19 . The composition of claim 7 , wherein said oligomers have an average chain length of 2 to 25 and wherein said oligomers further comprise residues of 1,4-cyclohexanedimethanol (CHDM), neopentyl glycol, isophthalic acid, and combinations thereof.
20 . The composition of claim 7 , wherein said solvolysis coproduct composition has a viscosity of at least 0.01 poise (P), measured using a Brookfield R/S rheometer with V80-40 vane spindle operating at a shear rate of 10 rad/s and a temperature of 250° C., and wherein said solvolysis comprises methanolysis, said principal glycol comprises ethylene glycol, and wherein said principal terephthalyl product comprises dimethyl terephthalate (DMT).