Use of multifunctional CO2 for depolymerization of polyethylene terephthalate
View Patent ↗A high-efficiency, low-energy consumption and environmental-friendly recycling technology for PETE plastic waste is disclosed. The degradation of PETE plastic waste includes a method for attacking the —O— ester linkage in the repeat unit of PETE plastic with water in saturated pressure and CO 2 in supercritical (Sc) conditions.
1. An environmentally friendly method for recycling polyethylene terephthalate (PETE), comprising:
pre-loading a supercritical high temperature reactor with a weight ratio of a polyethylene terephthalate and a deionized (DI) water in excess of 1:10;
injecting CO2 into the supercritical high temperature reactor at an injection pressure in excess of 500 psi;
sealing the weight ratio of the polyethylene terephthalate and the deionized water and the CO2 within the supercritical high temperature reactor;
setting a reaction temperature of the supercritical high temperature reactor with a controller, wherein the reaction temperature is in excess of 160° C.;
heating the weight ratio of the polyethylene terephthalate and the deionized water and the CO2 within the supercritical high temperature reactor to the reaction temperature; and
reacting the weight ratio of the polyethylene terephthalate and the deionized water and the CO2 within the reactor for a reaction duration in excess of 0.25 hrs.
2. The method of claim 1 , wherein the weight ratio of the polyethylene terephthalate and the deionized (DI) water is ≤1:30.
3. The method of claim 1 , wherein the reaction temperature is 240° C.
4. The method of claim 1 , wherein the reaction time is 2.0 hrs.
5. The method of claim 1 , further comprising:
collecting the CO2 after the completion of the reaction from the supercritical high temperature reactor.
6. The method of claim 1 , further comprising:
collecting a solid product reactant from the supercritical high temperature reactor, wherein the solid product reactant comprises polyenes and benzoic acid crystals; and
collecting a liquid product reactant from the supercritical high temperature reactor, wherein the liquid product reactant comprises ethylene glycol.