The Fe-Co-Cu supported on MWCNT as catalyst for the tri-reforming of methane – Investigating the structure changes of the catalysts

• Published in: Fuel (Guildford) 2019-11, Vol.256, p.115917, Article 115917
• Main Authors: Kozonoe, Camila Emilia, de Paiva Floro Bonfim, Rodrigo, Brito Alves, Rita M., Schmal, Martin
• Format: Article
• Language: English
• Subjects: Bimetals; Carbon; Carbon dioxide; Catalysis; Catalysts; Chemical synthesis; Cobalt; Copper; Feed composition; Functionalized MWCNTs; Iron; Metals; Methane; Methane Tri-reforming; Morphology; Reforming; Steam
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2019.115917

•Syntheses of Fe, Cu and Co nanoparticles nanocomposites on multi-walled carbon nanotubes (MWCNTs).•The controlling incorporation of Cu/Co and Fe nanoparticles in the carbon nanotubes.•The tri-reforming on (Fe@MWCNT/Metal, (Cu/Co)) catalysts presented high conversions.•XRD showed the appearance of different species and phases before and after reaction.•The feed H2, O2 and CO suggests a redox process of the catalysts during the reaction. In this work we synthesized Fe-Co-Cu catalysts supported on MWCNT, using a selective mode of addition of metal on functionalized MWCNT as mono and bimetallic catalysts. The Fe was inserted in the MWCNT after functionalization and Cu impregnated selectively. Co was added in sequence. The (Fe@MWCNT/Metal, (Metal = Cu and/or Co)) catalysts were tested for methane tri-reforming at 800 °C and GSVH 60,000 h−1, for 24 h. The Fe@MWCNT/Cu catalyst was more active and very stable compared to the Fe@MWCNT/CuCo. The influence of the feed composition CH4:CO2:O2:H2O and H2/CO ratio were tested, indicating prevailing steam and reverse WGSR reactions. Both catalysts were very stable for 24 h. However, TG results of the functionalized MWCNT indicated destruction of the carbon at higher temperature in the presence of oxygen. In view of the good stability and high activity of these catalysts during the tri-reforming at 800 °C we searched the causes, analyzing the structure and morphology of these materials, using different methods, before and after reaction. In fact, the functionalized MWCNT was destroyed for this reaction condition. However, TGA, MEV-FEG, Raman and XRD results showed the presence of very small amounts of carbon and the appearance of different species and phases before and after reaction. These results evidenced that the functionalized MWCNT is like a sacrificial support, dispersing very well the active and metal oxide species, and the formation of new phases as isolated active and stable nano particles, which inhibit carbon formation.