Catalysts and method for producing recycled polyester
The present invention describes the preparation of heterogeneous catalysts of mixed oxides based upon niobium and mixed oxides of zinc, manganese, nickel, cobalt and/or aluminum, originating from hydrotalcites (HTs) as precursor phase of heterogeneous catalysts, and application thereof in the chemical recycling of poly(ethylene terephthalate) (PET) for the production of metal free bis(hydroxy)ethylene (BHET) monomers and oligomers having a processing performance similar to that of the homogeneous catalysis system.
1 . A catalyst for the obtainment of recycled polyester, comprising the following general formulas:
(Zn 0.67 Mn 0.33 ) (1-x) Al x (OH) 2 (CO 3 ) x/2 .m H 2 O (II);
(Ni a Mn b ) (1-x) Al x (OH) 2 (A n− ) x/n .m H 2 O (IV);
(Zn a Mn b ) (1-x) Al x (OH) 2 (A n− ) x/n .m H 2 O (V); and
(Co 0.67 Mn 0.33 ) (1-x) Al x (OH) 2 (CO 3 ) x/2 .m H 2 O (VII),
wherein
0.2 ≤x≤ 0.5,
0.1 ≤a/b≤ 5,
A n− =anion of compensation, which may be carbonate, terephthalate or another anion, and
m= 1−(3/2) x+ 0.125.
2 . The catalyst of claim 1 , the catalyst having the following general formula:
(Co 0.67 Mn 0.33 ) (1-x) Al x (OH) 2 (CO 3 ) x/2 .m H 2 O (VII),
wherein x=0.20 and m=1−(3/2)x+0.125.
3 . A catalyst for the obtainment of recycled polyester, the catalyst consisting essentially of one of the following general formulas:
(Zn 0.67 Mn 0.33 ) (1-x) Al x (OH) 2 (CO 3 ) x/2 .m H 2 O (II);
(Ni a Mn b ) (1-x) Al x (OH) 2 (A n− ) x/n .m H 2 O (IV);
(Zn a Mn b ) (1-x) Al x (OH) 2 (A n− ) x/n .m H 2 O (V); and
(Co 0.67 Mn 0.33 ) (1-x) Al x (OH) 2 (CO 3 ) x/2 .m H 2 O (VII),
wherein
0.2 ≤x≤ 0.5,
0.1 ≤a/b≤ 5,
A n− =anion of compensation, which may be carbonate, terephthalate or another anion, and
m= 1−(3/2) x+ 0.125.