Study of polyester degradation by sub/supercritical ethanol and enhancement of carbon dioxide

Efficient Alcoholysis of Poly(ethylene terephthalate) by Using Supercritical Carbon Dioxide as a Green Solvent

“…The reaction conversion peaked at roughly 98% and 60%, respectively, when the molar ratios of CO 2 to methanol and ethanol reached 0.6 and 0.2, respectively. This is comparable with the results obtained by Liu [ 22 , 23 ] et al, where CO 2 was used to promote PET depolymerization with ethanol and methanol. It is predicted that when the partial pressure of carbon dioxide increased, some of the ethanol involved in the reaction dissolved in the carbon dioxide above the phase interface, resulting in a reduction in the amount of ethanol involved in the reaction.…”

“…Liu et al [ 22 ] obtained 95% DMT yield in only 40 min via the methanol depolymerization of PET by using supercritical CO 2 at 543 K and 10 MPa. Yu et al [ 23 ] found the optimal depolymerization conditions for PET/PE at 543 K, with both ethanol and CO 2 at an initial injection pressure of 2.0 MPa. Li and Guo et al [ 24 , 25 ] conducted PET hydrolysis using a solid acid catalyst in ScCO 2 and proposed a depolymerization mechanism wherein water molecules and hydrated hydrogen ions enter the non-crystalline area of PET through the dissolution of ScCO 2 until achieving the complete hydrolysis of PET.…”

Subcritical CO2–H2O hydrolysis of polyethylene terephthalate as a sustainable chemical recycling platform

“…31 Another application is the use of CO 2 for chemical deconstruction of plastics. [32][33][34][35][36] For instance, Liu and Yin reported that the addition of CO 2 to the supercritical methanolysis of PET resulted in superior dimethyl terephthalate (DMT) yields (up to 95%) relative to the process without CO 2 . 32 Recently, Yu et al reported that the addition of 2 MPa of CO 2 to the ethanolysis of PET resulted in 37% higher product yield in comparision with CO 2 -free ethanolysis.…”

“…32 Recently, Yu et al reported that the addition of 2 MPa of CO 2 to the ethanolysis of PET resulted in 37% higher product yield in comparision with CO 2 -free ethanolysis. 34 and hydronium ions into the amorphous region of PET matrix. 33 The dissolution of CO 2 in H 2 O provides a tunable acidic medium through the generation of carbonic acid (H 2 CO 3 ) in situ, which loses protons to form bicarbonate (HCO 3…”

“…32 Recently, Yu et al reported that the addition of 2 MPa of CO 2 to the ethanolysis of PET resulted in 37% higher product yield in comparision with CO 2 -free ethanolysis. 34 Li et al investigated the mechanism of hydrolysis of waste PET bottles in the presence of a solid super-acid catalyst (SO 4 2− /TiO 2 ) and supercritical CO 2 (scCO 2 ) and reported that scCO 2 improve the efficiency of the process due to its ability to carry more H 2 O and H 3 O + inside the substrate. 37 Also, the hydrolysis of waste bottle PET in WOx/TiO 2 solid acid catalysts and scCO 2 was investigated by Guo et al , who reported that scCO 2 promotes the swelling of the substrate and carries H 2 O and hydronium ions into the amorphous region of PET matrix.…”