Effect of coexistence of siloxane on production of hydrogen and nanocarbon by methane decomposition using Fe catalyst

Biogas derived from sewage sludge contains CO₂, siloxane, and methane. In this study, the effect of coexistence of siloxane on the production of hydrogen and carbon nanofiber by methane decomposition using iron oxide-alumina catalyst was investigated. The catalyst was reduced by heating in a flow of methane. Siloxane addition to methane caused a catalytic activity at lower temperatures, shortened the induction period prior to the activity, and accelerated catalytic deactivation. Thermal decomposition of siloxane can occur at a lower temperature compared to that of methane. Carbon species formed by the siloxane decomposition may have a higher reducibility than methane does. The reactivity may lead to a carbon deposition at a lower temperature. Coexistence of CO₂ and siloxane can prolong a catalytic lifetime because CO₂ may inhibit the carbon deposition on catalyst to some extent.