Chemical Recycling of PET with Solid State Shear Pulverization Technology

摘要

Post-consumer PET (polyethylene terephthalate) bottles have been recycled into film and sheet products ever since the Containers and Packing Recycling Law came into effect in 1997. There has been a growing need, however, for a chemical recycling process. In this process post-consumer PET bottles are recycled into monomers that can be used as feed stocks for the recycled production of PET bottles for beverages. This paper reveals a chemical recycling process using an alkali solution in order to depolymerize PET material in to its monomers (terephthalic acid and ethylene glycol) within a short time. Unlike other researchers, we did not use the flakes of PET, but used powdered PET produced based on solid state shear pulverization (SSSP) technology to achieve maximum yield (98%) and purity (95%) of the monomers in a short reaction time. The powdered PET has unique physical properties that affect experiment conditions temperature and pressure. The resulting terephthalate salt was treated with sulfuric or hydrochloric acid to yield highly pure terephthalic acid. Results show that the best percentage conversion of PET flakes is 1.5mol/l NaOH for 2 hours in 200 ℃ and for PET powder 1.5 mol/1 NaOH for 1.5 hours inl50℃.