Banca de QUALIFICAÇÃO: ADRIANA PERPETUA FIGUEIREDO PAULISTA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : ADRIANA PERPETUA FIGUEIREDO PAULISTA
DATE: 29/02/2024
TIME: 14:00
LOCAL: videoconferência
TITLE:

Synthesis of carbon nanotubes from the catalytic ethylbenzene conversion of over SrFe₁₂O₁₉/SiO₂ oxides: Application in the photodegradation of the remazol red dye

KEY WORDS:

carbon nanotube; strontium hexaferrite; ethylbenzene; CVD method; photocatalysis

PAGES: 60
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Cinética Química e Catálise
SUMMARY:

Carbon-based materials have stood out due to their variety of applications such as photocatalysis. Thus, strontium hexaferrite dispersed in silica was prepared by the Pechini method and used as a catalyst in the ethylbenzene reaction to produce carbon filaments and subsequent application in the photodegradation of the remazol red dye. The presence of SrFe₁₂O₁₉, Fe₂O₃ and amorphous silica phases was confirmed according to XRD, Raman and XPS analysis. The SEM and TEM results of the oxides indicate cluster and sponge-like morphology. It was possible to observe the formation of carbon filaments by SEM analysis after the CVD method that arose during the catalytic ethylbenzene reaction. TEM images confirm the generation of carbon nanotubes (~67 nm). The XRD after reaction shows the formation of graphite carbon, SrFe₁₂O₁₉, amorphous SiO₂, and Fe⁰ phases, confirming the hematite reduction. The growth of nanotubes occurs from metallic iron, considering that the tip of the tube contains only iron, according to EDS results. The Raman spectrum exhibited the characteristic D and G bands of carbon, where the I_D/I_G ratio decreased with increasing temperature, indicating an increase in carbon encapsulation with increasing temperature. The reaction with the best catalytic performance achieved an average ethylbenzene conversion of 99% was more selective to ethene (~ 93%) at 650°C. Furthermore, it was possible to carry out a simple theoretical-computational study regarding the distribution of the sites in a 2D plane by constructing maps and proposing a mechanism for the carbon nanotubes formation from the ethylbenzene conversion. Finally, the obtained materials were applied in the remazol red dye degradation, achieving complete degradation in 15 min for the material synthesized at 650°C.

COMMITTEE MEMBERS:
Externo à Instituição - MAICON OLIVEIRA MIRANDA - IFPI
Externo ao Programa - 1674707 - MARCO ANTONIO MORALES TORRES - UFRNInterna - 1308577 - SIBELE BERENICE CASTELLA PERGHER
Presidente - 2087667 - TIAGO PINHEIRO BRAGA