Improved method for recycling pet by alcoholysis
OwnerRaouf Medimaghinventor
Life of this patent
Estimating the term…
Abstract
The present invention relates to the field of recycling PET-type plastics commonly used for the manufacture of disposable plastic bottles, food trays, textiles, etc. More specifically, it relates to a method for converting PET into dimethyl terephthalate (DMT) in a few hours (less than 5 hours) by means of a complete reaction resulting in a product free of impurities. The depolymerisation step is carried out in the presence of a monoalcohol as well as an organic base with a guanidine or amidine unit, and a second base which may be either an inorganic base or an ether oxide. These two bases are present in catalytic amounts relative to the amount of PET to be treated.
Claims20
A method for recycling polyethylene terephthalate (PET) plastic waste into a powder of terephthalate ester monomers comprising three steps:
- a. a step of milling the waste to produce fragments;
- b. a step of pre-treating the fragments to facilitate their depolymerization;
- and
- c. a step of depolymerizing the PET in an ester of terephthalate and monoethylene glycol (MEG), in the presence of (i) an organic base comprising an amidine or guanidine unit and (ii) an etheroxide base of the sodium methoxide or potassium methoxide type, or inorganic base of the sodium hydroxide or potassium hydroxide type;
- wherein step c. is done:
- in that the bases are present in catalytic amount relative to the amount of PET;
- in the presence of excess monoalcohol relative to the amount of PET, and
- by heating between 25° C. and 80° C. for a period of between 30 minutes and 5 hours.
A method for recycling polyethylene terephthalate (PET) plastic waste into a powder of terephthalate ester monomers, comprising:
- milling the waste to produce fragments;
- pre-treating the fragments to facilitate their depolymerization;
- and
- depolymerizing the PET in an ester of terephthalate and monoethylene glycol (MEG), in the presence of (i) an organic base comprising an amidine or guanidine unit and (ii) an etheroxide base of at least one of sodium methoxide, potassium methoxide, sodium hydroxide, or potassium hydroxide;
- wherein, during the depolymerization, the organic base and the etheroxide base are present in catalytic amount relative to the amount of PET, the depolymerization is carried out in the presence of excess monoalcohol relative to the amount of PET, and the PET is heated to a temperature between 25° C. and 80° C. for a period of between 30 minutes and 5 hours during the depolymerization.
Dependencies are inferred from the claim text.