The polyoleﬁns production has increased rapidly in the 40 years to make polyoleﬁns the major tonnage plastics material worldwide. In 2003, 55 million tons of polyethene and 38 million t/a polypropene were produced . These products are used for packing material, receptacles, pipes, domestic articles, foils, and ﬁbers. Polyoleﬁns consist of carbon and hydrogen atoms only and the monomers are easily available. Considering environmental aspects, clean disposal can be achieved by burning or by pyrolysis, for instance. Burning involves conversion to CO2 and H2O, exclusively.