Produção de nanomateriais a base de carbono obtidos a partir da decomposição catalítica de metano
Resumo
The natural gas reforming routes are consolidated technologies in the production of H2, however, these
routes produce significant amounts of greenhouse gases and require the separation and purification of
H2. The catalytic decomposition of methane (CDM) process is a promising alternative to traditional
processes, as it produces COx-free H2 and carbon nanoparticles (nanotubes, carbon nanofibers or
graphene-based structures) with wide applicability. To increase the competitiveness of CDM, it is
necessary that the carbon produced has a high commercial value. Thus, the quality control of carbon
characteristics is essential, as it is expected that carbon nanostructures free of defects and with uniform
characteristics have remarkable mechanical, electronic and magnetic properties. However, the quality
control of these carbon nanostructured materials is still very low by this process due to several factors
that influence their production. To prepare high quality carbon nanotubes or nanofibers and, at the
same time, produce H2 with a high yield, it is necessary to develop active and stable catalysts. In the
present research project, catalysts based on Ni and Fe were prepared by the coprecipitation,
impregnation and fusion method and tested in the decomposition of CH4. The materials were
characterized by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy
(XPS), N2 physisorption, temperature programmed reduction (TPR), Mössbauer spectroscopy,
thermogravimetric analysis, transmission and scanning electron microscopy (TEM and SEM). The
synthesis method influenced the metal-support interaction, particle size and specific surface area. The
catalysts prepared by the coprecipitation and fusion method were more active during the reaction
producing fishbone and bamboo carbon nanofibers on Ni and Fe catalysts, respectively. The
impregnation method was inefficient in generating nanofibers, promoting the formation of short and
irregular fibers. Carbon production was up to 11.8 grams of carbon per gram of iron and 1.4 grams of
carbon per gram of nickel for materials prepared by the coprecipitation method. Subsequently, the
functionalization of the catalysts used was performed and it was observed that there was an increase in
the amount of oxygenated functional groups on the carbon surface, which expands the application and
use of these materials.
Collections
Os arquivos de licença a seguir estão associados a este item: