Chemical Recycling by Degradation of Low-Density Polyethylene into Petrochemicals Using Gallium Zeolite Catalysts

Degradation of low-density polyethylene (LDPE) containing small amounts of other plastics, which are polyvinyl chloride (PVC), polyamides 66 and 6 (PA66 and PA6), polyethylene terephthalate (PET) and polystyrene (PS), has been investigated using gallium zeolite catalysts. Gallium silicate catalyst showed a high activity for converting LDPE into aromatic hydrocarbons, and its catalytic activity was hardly influenced by the presence of PET and PS in the plastic mixtures. However, PVC and PA66 mixed with LDPE caused significant reduction of the catalytic performance probably because of deposition of Cl- and N-containing compounds and more formation of coke on the catalyst surface. Ga/H-ZSM-5, newly prepared in this work, was found to be promising as a catalyst for producing aromatics from degradation of PVC- and PA66-containing LDPE. The catalyst has a high potential for use in advanced chemical recycling of waste polyolefins. (C) 2013, The Society of Polymer Science, Japan