Development of first-stage co-liquefaction of Chinese coal with waste plastics

Polyethylene (PE), polypropylene (PP), and polystyrene (PS), etc. have been successfully converted to oil under typical direct liquefaction conditions (410–450 °C, reaction time of 60 min, 10 MPa of H2 cold) with Chinese coal. A series of liquefaction experiments were run using ground coal and plastic waste, individually and in combination. Results on individual plastics showed that high density PE (HDPE) was by far the most difficult of the model plastics to convert, higher conversions could be obtained with higher temperatures. Co-liquefaction experiments were performed on coal–plastic mixtures (usually 1:1 mixtures) using a Chinese Xianfeng lignite with the fly ash of molybdenum concentrates calcined (FAMo) as catalyst. The oil yields except Xianfeng lignite–HDPE co-liquefaction were as high as 60.3–78.1%, while the total conversions reached levels of over 95%. Anyway, oil yields for Chinese coal–plastic co-liquefaction were higher, typically by 5.1–22.6%, than the average of the oil yields for the coal and plastic alone, hydrogen consumption was also reduced by 7.7–17.9%, implying synergistic effects in co-liquefaction reaction of Chinese coal and waste plastics (WP).