Methods for removing catalyst residue from a depolymerization process stream
AssigneeCyclics Corporation
InventorsPeter D. Phelps, Jimmy Lynn Webb, David Patrick Phelon, Paul M. Andrusyszyn
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Abstract
The invention relates to methods and systems for selective removal of catalyst residue from a depolymerization product stream without a water quench, as well as methods and systems for subsequent recovery of residual linear oligomer. The substantially metal-free and substantially water-free residual oligomer byproduct can then be advantageously used as recyclate in a process for preparing MPO. For example, the residual oligomer recyclate can be used as a reactant in the polymerization and subsequent depolymerization (cyclization) of low-acid polyester to form MPO.
Claims42
A method for precipitating a metal-containing compound from a mixture without addition of water, the method comprising the step of exposing a mixture to a temperature of at least about 200° C. for at least about 5 minutes, the mixture comprising:
- (a) a metal-containing compound;
- (b) an organic solvent;
- (c) a linear oligomer;
- and optionally
- (d) a macrocyclic polyester oligomer,
- wherein at least a portion of the linear oligomer remains dissolved in the organic solvent following the exposing step.
A method for removing catalyst residue from a depolymerization process stream, the method comprising the steps of:
- (a) exposing a mixture to heat to produce a macrocyclic polyester oligomer, the mixture at least initially comprising:
- (i) a polyalkylene terephthalate product having an acid concentration no greater than about 10 meq/kg;
- (ii) an organic solvent;
- and
- (iii) a depolymerization catalyst;
- and
- (b) exposing at least a portion of the mixture of step (a) to a temperature of at least about 200° C. for at least about 5 minutes to precipitate a residue that comprises or is formed from the depolymerization catalyst.
A method for isolating a filtrate comprising a linear oligomer from a depolymerization process stream, the method comprising the steps of:
- (a) exposing a mixture from a depolymerization process stream to a temperature of at least about 200° C. for at least about 5 minutes to precipitate a metal-containing residue;
- and
- (b) filtering at least a portion of the mixture following step (a) to produce a filtrate comprising a linear oligomer.
Dependencies are inferred from the claim text.