Simultaneous production of hydrogen and carbon nanostructured materials from ethanol over LaNiO3 and LaFeO3 perovskites as catalyst precursors

Abstract

The simultaneous production of hydrogen and carbon materials from ethanol was studied using the perovskites LaNiO3 and LaFeO3 as catalyst precursors. The reaction was performed at temperatures between 700°C and 900°C with ethanol concentration of 50vol%. Using LaNiO3, the yield of carbon materials is maximum at low temperature due to the presence of dense carbon like nanofibers while at higher temperatures, multiwalled carbon nanotubes are produced. A reaction temperature of 900°C is necessary to obtain hydrogen and carbon materials with LaFeO3. The hydrogen yield reaches 16.2L per hour and per gram of catalyst, hydrogen representing 70% in volume of the products in gas phase while methane is only 3.6%. We show that the perovskite LaFeO3 is reduced in situ under ethanol leading to the formation of Fe0 and Fe3C responsible for the carbon growth. A scheme is proposed for the growth of carbon material from the species obtained by LaFeO3 reduction. The morphology of carbon materials depends on the nature of the catalyst, MWCNTs are produced from LaNiO3 as catalyst precursor while twisted nanofibers are obtained from LaFeO3 at 900°C.