Predicting gasification rates of pyrolytic graphite deposited from methane

This work describes the gasification of carbon produced during the pyrolysis of methane. Carbon was deposited on nonporous α−Al₂O₃ at temperatures ranging between 950 and 1150 °C. The time α−Al₂O₃ was in contact with methane was varied between 60 and 8400 s. Gasification tests were performed in the range of 1000 to 1100 °C and steam, CO₂ and air were used as oxidizer. It was observed that the gasification rate cannot be described by only parameters related to the gasification conditions (temperature, pressure, gas composition). In fact, it became clear that information about the carbon is needed in the gasification rate equation. The H/C ratio and the peak oxidation temperature, as reactivity measures, turned out not to relate uniquely to the gasification rate and are thus not suited as completing parameters. However, it was possible to relate the gasification reactivity of the carbon to the pyrolysis conditions (temperature, contact time between α−Al₂O₃ and CH₄) under which it was produced. After parameterization of the thus obtained rate equation using data obtained in a single particle reactor, an adequate prediction on the gasification of carbon deposited by pyrolysis of methane in a fixed could be made. The developed method is therefore a suitable way of predicting gasification rates for reactor design purposes.