Product distribution from Yallourn coal by methane microwave plasma conversion

A direct conversion technology of brown coal into relatively important fuels, raw-material gases, and residues of upgraded carbon content by use of methane microwave plasma was developed. Changes with time in the C, H, O contents of each product from Yallourn coal were examined. The desiccated coal was packed in the middle of a cylindrical quartz tube reactor of 25.0 mm inside diameter and 400 mm length. 2.45 GHz of microwaves with desired power level controlled by a waveguide tuner was irradiated onto the upperside of the packed bed by supplying methane (4.0 kPa) successively, and the following results were obtained: (1) Both the C and H supplied from methane were converted into gaseous products (mainly of acetylene and hydrogen). (2) Within 2 minutes of reaction, C contained in the coal was converted to oily products composing mainly of aliphatic hydrocarbons in the H/C ratio range from 1.5 to 1.6; however, after 5 minutes of reaction, it was converted to carbon dioxide. (3) Almost all of the O in coal was converted to and distributed as gaseous products (finally as carbon monoxide) via disintegration of the carboxyl groups and homogeneous transformation of the carbon dioxide produced.