Recycling of waste PET‐bottles using dimethyl sulfoxide and hydrotalcite catalyst

Abstract

The degradation of PET bottles has been successfully achieved using hydrotalcite as catalyst and dimethyl sulfoxide (DMSO) as solvent. The reaction was carried out at boiling point of DMSO (190°C) and degradation was complete in 10 min. The oligomer (tetramer) obtained was treated with NaOH at room temperature in methanol to get dimethyl terephthalate (DMT) and ethylene glycol (EG). Thus, it is a safe and cleaner process. Oligomer was characterized by MS,13C‐NMR, X‐ray diffractometric, and thermogravimetric analysis. DMT and EG were characterized by GC‐MS. DMT was also characterized by FT‐IR. GC‐MS analysis shows that the purity of DMT was 99%. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012

Chemical Recycling of PET Wastes with Different Catalysts

“…Hydrotalcite catalyzed synthesis of polyethylene terephthalate was studied to clarify the effect of hydrotalcite properties on its catalytic activity [15]. Hydrotalcite was modified by various treatments to tune its activity as a polycondensation catalyst [14]. Hydrotalcite activity was found to decrease upon calcination.…”

“…Replacement of the carbonate anions of hydrotalcite by more nucleophilic ones like hydroxide and alkoxide groups resulted in a faster polycondensation reaction. Hydrotalcite has two assembly orders: primary, lamination of sheets into plates, and secondary, agglomeration of plates into particles [14,15]. Hydrotalcite with larger sheet size showed lower activity.…”

“…The degradation of PET bottle was achieved in 10 minutes using hydrotalcite (Al:Mg:CO 3 ) as catalyst in solvent DMSO. The oligomer on treatment with sodium hydroxide in methanol at room temperature resulted in the precipitation of MT and EG in methanol, according to the following chemical reaction (Scheme 2) [14].…”

Recycling of poly(ethylene terephthalate) – A review focusing on chemical methods

“…Neutral hydrolysis of PET is generally conducted with excess water at high temperature ranges between 115-420°C and high pressure ranges from 10 to 480 bar. Correspondingly, reaction times are up to 7 hours [149][150][151][152][153][154][155][156][157][158]. Güçlü et al [149] found that the solvent xylene provided greater de-polymerization of PET, whereas the catalysts zinc acetate or potassium hydroxide had negligible effect.…”

“…They obtained low molecular weight oligomers (540+ 2047 g·mol -1 , Table 2) with yields of 97+99%. Other studies investigated the effects of different reaction parameters on neutral hydrolysis of PET, such as catalysts (zinc acetate, potassium hydroxide, phase transfer catalyst, hydrotalcite) [151,153,156], steam or plasma treatment [154,155] and microwave irradiation [157]. Although having different foci in these papers, the monomer TPA was obtained as reaction product in yields of 90-100% (Table 2).…”