Methane Conversion over Vacuum Carbon Black: Influence of Hydrogen

Abstract

<p>Methane pyrolysis over vacuum carbon black has been studied in the temperature range 550–1000 °C. The methane conversion degree and selectivity with respect to ethene and propene do not depend on the initial concentration of methane <em>i.e. </em>the process order with respect to methane is first. The selectivity with respect to pyrolytic carbon is antibate to the methane initial concentration. Hydrogen introduced to methane inhibits formation of pyrolytic carbon and aromatics especially in methane pyrolysis. The methane conversion degree in pyrolysis of methane/hydrogen mixture is inversely proportional to the initial concentration of hydrogen while the selectivity with respect to ethene being symbate to the one. A hypothesis on the reason of inhibition of pyrolytic carbon formation by hydrogen is proposed. Methane pyrolysis is a homogeneous-heterogeneous reaction up to 850°C, but homogeneous reaction is prevalent at the temperature range of maximal selectivity with respect to alkenes.</p>