Hydrogen generation from polyethylene by milling and heating with Ca(OH)2 and Ni(OH)2

A process to produce hydrogen from polyethylene [–CH2–]n (PE) is developed by milling with Ca(OH)2 and Ni(OH)2 followed by heating the milled product. Characterizations by a set of analytical methods of X-ray diffraction (XRD), infrared spectroscopy (FT-IR), thermogravimetry–mass spectroscopy (TG/MS) and gas chromatography (GC) were performed on the milled and heated samples to monitor the process. It has been observed that addition of nickel hydroxide as well as increases in milling time and rotational speed of the mill is beneficial to the gas generation, mainly composed of H2 and CH4, CO, CO2. Gaseous compositions from the milled samples vary depending on the added molar ratio of calcium hydroxide. H2 emission occurs between 400 and 500 °C, and H2 concentration of 95% is obtained from the mixture of PE/Ca(OH)2/Ni(OH)2 (C:Ca:Ni = 6:14:1) sample, and the concentrations of CO and CO2 remain below 0.5%. The process offers a novel approach to treat waste plastic by transforming it into hydrogen.