LIQUID FLUIDS FROM THERMO-CATALYTIC DEGRADATION OF WASTE LOW-DENSITY POLYETHYLENE USING SPENT FCC CATALYST

ABSTRACT: The widely-used plastics, especially low-density polyethylene (LDPE), have resulted in a considerable accumulation of plastics in the waste stream, causing a global environmental problem. Therefore, the research aims to examine the thermal and catalytic degradation of waste LDPE plastic using spent fluid catalytic cracking (FCC) catalyst and compare the properties of the produced liquid oils with commercial fuels. The potential of converting the most energy from waste plastics to valuable liquid oil, gaseous, and char was investigated. A batch reactor was used to thermally and catalytically degrade LDPE at temperatures 350 to 550oC and catalyst to plastic ratio of 0.10 to 0.25. The physical properties of the produced liquid oils, flash point, pour point, viscosity, API-gravity, carbon residue, density, etc., were determined using standard methods. We characterized the chemical properties of produced pyrolysis liquid oils with Gas chromatography-mass spectrometry (GC-MS). The liquid oil, gas, and char produced at catalyst to plastic ratio of 0.20 at 500oC were 92.7 wt.%, 6.1 wt.%, and 1.2 wt.% respectively. The thermal pyrolysis at 500 oC gave 76.6 wt.%, 20.7 wt.%, and 2.7 wt.% for produced liquid oil, gas, and char, respectively. The GC-MS shows that the produced LDPE liquid oil contains many hydrocarbons from C7-C29. The major hydrocarbons common to LDPE are benzene, 1, 3 dimethyl benzene, and toluene. The produced liquid oil’s properties compare favorably with that of commercial fuels.