Fe@CNT-monoliths for the conversion of carbon dioxide to hydrocarbons: structural characterisation and Fischer–Tropsch reactivity investigations

Abstract

The direct conversion of carbon dioxide to hydrocarbons with a high economic value, such as olefins, can contribute to preventing further green house gas emissions in the atmosphere. In this paper, we report a synthesis, characterisation and catalytic study centred on iron nanoparticle–carbon nanotube arrays grown on monoliths (Fe@CNT-m). These have been used for the catalytic conversion of carbon dioxide to hydrocarbons, showing superior properties than the powder form. The monolith-supported structure also overcomes limitations of the powder catalyst, such as high-pressure drops and potential toxicity of airborne CNT powders, that have, so-far, limited its use in industry. The optimal process conditions (temperature pressure, flow rate and reaction time) have been identified along with deactivation mechanisms. The different catalytic performance of the residual iron NPs outside and inside the CNTs has also been investigated.