Efficient disposal of waste polyolefins through microwave assisted pyrolysis

Waste or contaminated polyolefins were disposed through microwave assisted pyrolysis (MAP) using tires or carbonaceous char as microwave (MW) absorber. High density polyethylene (HDPE) was converted into waxy products when standard heating was employed. However HDPE was converted into a low viscosity fraction by using a very low MW power, but a not completed conversion was achieved while PP was always converted into a liquid having a low viscosity. Using an oven containing a system able to fractionate the vapor formed, the residence time of the waxy products in the oven was improved together with the overall pyrolysis efficiency. However the time of the process was strongly reduced with respect to processes using a classical heating. The liquid fraction from HDPE contained linear alkanes and 1-alkenes with negligible formation of branched, cyclic, or aromatic hydrocarbons, while liquid from PP was formed by a mixture of methyl-branched alkane and alkenes, and sometimes aromatics as a function of pyrolysis conditions.