Fuels obtained by thermal cracking of individual and mixed polymers

Utilization of oils/waxes obtained from thermal cracking of individual LDPE (low density polyethylene), HDPE (high density polyethylene), LLDPE (linear low density polyethylene), PP (polypropylene), or cracking of mixed polymers PP/LDPE (1: 1 mass ratio), HDPE/LDPE/PP (1: 1: 1 mass ratio), HDPE/LDPE/LLDPE/PP (1: 1: 1: 1 mass ratio) for the production of automotive gasolines and diesel fuels is overviewed. Thermal cracking was carried out in a batch reactor at 450°C in the presence of nitrogen. The principal process products, gaseous and liquid hydrocarbon fractions, are similar to the refinery cracking products. Liquid cracking products are unstable due to the olefins content and their chemical composition and their properties strongly depend on the feed composition. Naphtha and diesel fractions were hydrogenated over a Pd/C catalyst. Bromine numbers of hydrogenated fractions decreased to values from 0.02 g to 6.9 g of Br₂ per 100 g of the sample. Research octane numbers (RON) before the hydrogenation of naphtha fractions were in the range from 80.5 to 93.4. After the hydrogenation of naphtha fractions, RON decreased to values from 61.0 to 93.6. Diesel indexes (DI) for diesel fractions were in the range from 73.7 to 75.6. After the hydrogenation of diesel fractions, DI increased up to 104.9.