From plastics to jet fuel range alkanes via combined catalytic conversions

Abstract

High carbon yields of jet fuel range alkanes were observed from plastics through a novel route. The integral processes were mainly performed via the catalytic microwave-assisted degradation of low-density polyethylene (a model compound of plastics waste) followed by hydrogenation process. The catalytic microwave degradation was carried out at 375 °C with catalyst to feed mass ratio of 0.1 or 0.2 to manufacture distinct proportions of aliphatic and cyclic hydrocarbons. It was observed that the carbon yields of the raw organics from the catalytic microwave degradation were 66.18 and 56.32%, respectively. Several variables were employed to estimate the optimal conditions for the production of alternative jet fuels in the hydrogenation process. With the presence of 10 or 20 wt% well-promoted ZSM-5 catalyst, the overall carbon yields of hydrogenated organics regarding raw plastics were approximately 54 or 63%. The alterations of reaction conditions did not have a remarkable effect on the overall carbon yield of hydrogenated organics. The raw organics (with the higher yield) could be hydrogenated to fit JP-5 navy fuel at 200 °C for 2 h using the 10 wt% Raney Ni catalyst; while the raw organics (with the lower yield) could be hydrogenated to match high energy-density jet fuels (e.g. RJ-5 and JP-10) under very low-severity conditions. During the hydrogenation process, home-made Raney Ni catalyst showed more notable catalytic performance than that of as-purchased Raney Ni 4200 catalyst. In this regard, the catalytic conversions of plastics can be regarded as a clear breakthrough to produce various grades of jet fuels.