(724c) Upcycled Group IV Base Oil Lubricants Generated from Pyrolysis of Military Waste Polyethylene and Polypropylene Plastics

Group IV base oil lubricants are one of the high value products produced by the petroleum industry which are used as synthetic oils for the purpose of lubrication over a wide range of temperatures due to their superior oxidative stability at elevated temperatures and lower pour points at extremely low temperatures. Traditionally, the petroleum industry uses synthetic chemical processes to generate ethylene through crude oil or natural gas cracking followed by polymerization to target a specific carbon range (typically C8-C12) that is further distilled to produce pure normal alpha-olefins (NAOs). These NAOs are then catalytically synthesized and hydrogenated to obtain lubricant grade molecular weight range (C30 trimers) called poly-alphaolefins (PAOs) that possess better tribological performance qualities such as viscosity and oxidation stability. However, one of the challenges for this process is overcoming contamination from sulfur and aromatic compounds that are naturally present in the crude petroleum feedstock. The fast pyrolysis process used in this study has the ability to produce the NAOs without sulfur or aromatic contamination due to the use of a purer feedstock in the form of waste plastic (high and low density polyethylene and polypropylene).

Fast pyrolysis of military waste polyethylene (PE) and polypropylene (PP) at elevated temperatures (450-550˚ C) thermally broke down the longer carbon chains into three products – wax, oil and gas - which were condensed into specific carbon molecular range using condensers operating at specific temperatures. In this study, the wax was collected at two temperatures 75˚ C and 250˚ C while the oil was collected at 25˚ C. Qualitative gas chromatography coupled with mass spectrometry showed that the wax and oil predominantly contained C10-C30 and C8-C17 molecular carbon ranges respectively in the form of paraffinic alkenes, predominantly, without sulfur or aromatics. These products were further fractionated in a distillation column to acquire C9-C12 normal alkene products which were catalytically coupled to form compounds with longer carbon branching typically possessing the C30 isomeric range mimicking the Group IV base lubricant oils. This presentation will report several measurements; kinematic viscosities at 40˚ C and 100˚ C, pour point, flash point, and thermal gravimetric analysis (TGA) were conducted to evaluate the thermal stability, differential scanning calorimetry (DSC) was used to estimate melting point, Fourier transform infrared spectroscopy (FTIR) & nuclear magnetic resonance (NMR) to predict the molecular arrangement and functional groups and, gel permeation chromatography for molecular weight estimation were used to evaluate the tribological properties of the obtained lubricant group IV base lubricant oil. This process is unique in its kind as it aims at generating a high-value synthetic lubricant from waste plastic without sulfur or aromatic contamination.