The conversion of waste polystyrene into useful hydrocarbons by microwave-metal interaction pyrolysis

Waste polystyrene was pyrolyzed at temperatures as high as the melting point of aluminum into styrene and other substituted aromatic compounds. This temperature was attained by the interaction of microwaves with aluminum in the form of a tightly coiled wire, strips, and cylinder. The rate of reaction was found to depend on the size, shape and form. The reaction was faster for the coil, slower for strips and negligible for the cylindrical form. The yields of pyrolysis were also found to depend on size, shape and form of the metal. The products of the pyrolysis were found to contain 88 wt % liquid, 9–10 wt % gases and residual char. The liquid portion was collected using cold traps and measured, whereas the amount of gas was obtained by taking difference. The liquid portion was analyzed using GC/MS and found that it contains substituted benzene in addition to polycyclic aromatics and condensed ring aromatics. The gases were identified using acetylide formation and Baeyerʹs test. The products, formation, mechanism of the reaction, and nature of products are discussed.