Methane pyrolysis in a hot filament reactor

An electrically heated platinum filament mounted inside a quartz tube was u sed as a high temperature flow reactor for methane pyrolysis. The reaction products included carbon and a mixture of hydrocarbons, mainly C1-C5 alkane s, alkenes, and benzene. The hydrocarbons were measured by gas chromatograp hy and the carbon gravimetrically. At 1275 degrees C filament temperature a nd 100ms residence time in the hot region of the reactor, methane conversio n was 19.7% and selectivity of hydrocarbon products 68%. Lowering the flow rate increased the conversion but lowered sharply the selectivity of hydroc arbon products. Coking of the filament surface gradually lowered the filame nt temperature and the conversion of methane. This deactivation process cou ld be slowed by adding a few percent of oxygen to the methane feed.