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Pyrolysis and hydrolysis of mixed polymer waste comprising polyethyleneterephthalate and polyethylene to sequentially recover

United States Patent

5,821,553
October 13, 1998
View the Complete Patent at the US Patent & Trademark Office
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A process of using fast pyrolysis in a carrier gas to convert a plastic waste feedstream having a mixed polymeric composition in a manner such that pyrolysis of a given polymer to its high value monomeric constituent occurs prior to pyrolysis of other plastic components therein comprising: selecting a first temperature program range to cause pyrolysis of said given polymer to its high value monomeric constituent prior to a temperature range that causes pyrolysis of other plastic components; selecting a catalyst and support for treating said feed streams with said catalyst to effect acid or base catalyzed reaction pathways to maximize yield or enhance separation of said high value monomeric constituent in said temperature program range; differentially heating said feed stream at a heat rate within the first temperature program range to provide differential pyrolysis for selective recovery of optimum quantities of the high value monomeric constituent prior to pyrolysis of other plastic components; separating the high value monomeric constituents; selecting a second higher temperature range to cause pyrolysis of a different high value monomeric constituent of said plastic waste and differentially heating the feedstream at the higher temperature program range to cause pyrolysis of the different high value monomeric constituent; and separating the different high value monomeric constituent.
Evans; Robert J. (Lakewood, CO), Chum; Helena L. (Arvada, CO)
Midwest Research Institute (Kansas City, MO)
08/ 350,392
December 6, 1994
CONTRACTUAL ORIGIN OF THE INVENTION The United States Government has rights in this invention under Contract No. DE-AC02-83H10093 between the United States Department of Energy and the Solar Energy Research Institute, a Division of the Midwest Research Institute.