Methane Pyrolysis over Carbon Catalysts

Abstract

<p>Methane pyrolysis at the temperature range of 550-1000 °C in gas flow reactor with fixed bed of mixed catalysts based on carbon materials of various structure (fullerene cocoons, fullerene black, vacuum black, cathode deposit, onion-like carbon, glassy carbon, carbon fibers, mineral shungite and graphite) has been studied. Methane pyrolysis products, including stoichiometric amount of hydrogen are C<sub>3</sub>-C<sub>4</sub> alkanes, C<sub>2</sub>-C<sub>4</sub> alkenes, aromatics and pyrolytic carbon. Methane pyrolysis is carried out both on a catalytic surface and in a volume and contribution of the surface is determined by pyrolysis temperature. Materials with curved carbon surface show an activity in methane dehydrogenation at lower temperatures, than materials with planar basic structure elements. Materials with a small specific surface area favor methane aromatization at 950–1000 °C with formation of mainly benzene, toluene and naphthalene. The primary activation of C–H bond in methane at temperatures of lower than 850 °C, as well as the multiple dehydrogenation conversions resulting in the formation of pyrolytic carbon and its precursors (aromatics), are, probably, heterogeneous reactions.</p>

Methane Conversion over Vacuum Carbon Black: Influence of Hydrogen

“…at various contents of Ar and H 2 . The basic invariable details of the experiments have been reported earlier [9].…”

“…Also we have noted that catalysts based on fullerene materials are more active than other ones based on carbon materials having planar basic structure elements [9,10]. In contrast to inert gas additions hydrogen additions to feed promoted a coking decrease and an increase of alkene yields [8,9]. In this paper we report kinetic data on pyrolysis of CH 4 /Ar and CH 4 /Ar/H 2 mixtures over a catalyst based on vacuum carbon black.…”

“…We have reported methane dehydrogenation and aromatization over catalysts based on carbon materials. Also we have noted that catalysts based on fullerene materials are more active than other ones based on carbon materials having planar basic structure elements [9,10]. In contrast to inert gas additions hydrogen additions to feed promoted a coking decrease and an increase of alkene yields [8,9].…”

“…A mixed catalyst containing 0.1 g (3.3 %) of carbon material named as vacuum carbon black [10] and 2.9 g of crushed (particles size of 0.25-0.5 mm) quartz has been used. Argon was used as an inert gas.…”

Catalysts for C–H functionalization: Platinum, gold and even nanodiamonds

“…Methane is activated at 500-700° C. A threshold value for FB as catalyst is 600° C. This value is by 250° and 100-200° C lower than the threshold for catalyst free reaction and in the presence of graphite (activated charcoal and others), respectively [143][144][145][146]. At the early stage of the reaction hydrogen is almost a single gaseous product which is an evidence of high activity of parent FB.…”