Impact of Carbon Dioxide on the Non-Catalytic Thermal Decomposition of Methane

Abstract

Economically and ecologically, the thermal decomposition of methane is a promising process for large scale hydrogen production. In this experimental study, the non-catalytic decomposition of methane in the presence of small amounts of carbon dioxide was analyzed. At large scales, natural gas or biomethane are possible feedstocks for the thermal decomposition and can obtain up to 5% carbon dioxide. Gas recycling can increase the amount of secondary components even further. Experiments were conducted in a packed flow reactor at temperatures from 1250 to 1350 K. The residence time and the amounts of carbon dioxide and hydrogen in the feed were varied. A methane conversion of up to 55.4% and a carbon dioxide conversion of up to 44.1% were observed. At 1300K the hydrogen yield was 95% for a feed of methane diluted in nitrogen. If carbon dioxide was added to the feed at up to a tenth with regard to the amount of supplied methane, the hydrogen yield was reduced to 85%. Hydrogen in the feed decreases the reaction rate of the methane decomposition and increases the carbon dioxide conversion.

Direct biogas reforming to turquoise H2 and carbon material in a catalytic fluidised-bed reactor

“…8,9 There are two main approaches for methane cracking: plasma pyrolysis 10 and catalytic pyrolysis. [11][12][13] However, the thermal decomposition of methane is also being investigated, 14 although the temperatures are much higher and therefore less interesting than with a catalyst. Because of thermodynamic and technological constraints, very high methane conversion is difficult to achieve in a steady state.…”

Methane Decomposition to Hydrogen Over Zirconia‐Supported Fe Catalysts–Effects of the Modified Support

“…At temperatures more than 550 °C, methane cracking is spontaneous and can happen even without the use of a catalyst [10] . To achieve total breakdown, the reaction needs temperatures higher than 1000 °C [11] . Nickel and cobalt catalysts are efficient for the CDM reaction at temperatures of 500 and 600 °C.…”

“… [10] To achieve total breakdown, the reaction needs temperatures higher than 1000 °C. [11] Nickel and cobalt catalysts are efficient for the CDM reaction at temperatures of 500 and 600 °C. However, these catalysts would deactivate quickly at higher temperatures.…”