Waste plastics: lignite mixtures co-liquefaction over Si/Al catalysts

Abstract

The results of an investigation of the conversion of lignite and post-consumer polymers into liquid products are reported in this paper. At first, a series of silica-alumina acidic catalysts were prepared by sol-gel chemistry with different Si/Al compositions and the catalysts ratio of Bronsted to Lewis acid sites was determined. Then thermal and catalytic col-iquefactions were attempted on 1/1 mixtures of lignite and waste plastics, e.g., PS, PISO and PE. It was found that the catalysts prepared enhanced oil formation in all cases although lignite and polymeric materials demonstrated a variety of catalytic characteristics. Thermal and catalytic reactions of polystyrene (PS) and polyisoprene (PISO) showed that both polymers were liquefied easily at 420°C while polyethylene (PE) did not interact promptly under the same conditions. The conversion of the solid materials correlated with the concentration of Bronsted acidity on the catalysts employed.