PYROLYTIC CARBON DEPOSITION FROM METHANE - AN ANALYTICAL APPROACH TO THE CHEMICAL PROCESS

The present work was conducted in order to investigate the effects of three important constraints, namely, temperature, flow-rate, and pressure, in the deposition process of pyrolytic carbon from methane, in the vicinity of 1000-1100°C, and at pressures between 150 and 400 mm Hg. The properties of the deposited carbon were studied, and the experimental setup enabled us to obtain a fairly complete qualitative and quantitative description of all the important intermediate reaction products. It is found that more intense pyrolysis conditions (higher temperature and pressure or lower flowrate) accelerate the later steps of the process more than the early ones, and that some particular intermediate polyaromatic hydrocarbons (e.g., anthracene) lead more efficiently to carbon than other ones (e.g., acenaphtylene). The pyrolysis mechanism remains essentially the same when methane is diluted with hydrogen. © 1990.