Experiments on Reaction of Polyethylene and Water under High Pressure and High Temperature

Hydrous and anhydrous pyrolysis of polyethylene under high temperature and high pressure was conducted in diamond anvil cell (DAC) apparatus. Reaction phenomena can be observed by microscope and be recorded by micrography during the experimental processes. At the meantime, in situ fluorescence change can be determined under high pressure. Compositions of gas products were analyzed by gas chromatographic technique. It shows that CH4 make up about 92% of the total gas hydrocarbon products, CO2 and very little solid residue were existed in the hydrous pyrolysis experiment. The results indicate that H2O participates in the chemical reaction directly, offering H to hydrocarbons and O to CO2. Anhydrous pyrolysis of polyethylene generates less gas hydrocarbons and much more solid residue than hydrous run. Thermodynamic theory was used to discuss reaction mechanism in the experiments. Compared polyethylene structure with kerogen, we infer that the ratio of hydrocarbons generation would be increased while H2O exist in the organic matter pyrolysis processes.