Banca de QUALIFICAÇÃO: JENNIFER ELLEN LIMA DA COSTA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : JENNIFER ELLEN LIMA DA COSTA
DATE: 26/06/2025
TIME: 09:30
LOCAL: Auditório do LABTAM
TITLE:

Calcium-doped LaNiO₃ Perovskites for Hydrogen Production via Dry Reforming of Methane.

KEY WORDS:

Dry Reforming of Methane; Hydrogen; Perovskite; Dopant; Calcium

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

The growing energy demand, combined with the dependence on fossil fuels, has exacerbated climate change and continuously increased the concentration of greenhouse gases (GHGs) in the atmosphere, making the development of technologies capable of mitigating these environmental impacts increasingly urgent. Dry reforming of methane (DRM), which uses methane (CH₄) and carbon dioxide (CO₂), two of the main GHGs, stands out as a promising alternative for the production of synthesis gas (H₂ and CO), simultaneously contributing to emission reduction and the generation of energy inputs. Nickel-based catalysts are widely employed in DRM; however, they present limitations related to coke deposition and sintering, which compromise their stability. In this study, LaNiO₃ perovskite catalysts were synthesized via the microwave-assisted combustion method, with modifications through calcium doping at different concentrations, aiming to improve catalytic activity and stability and to mitigate coke formation and sintering issues. The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), elemental mapping via energy-dispersive spectroscopy (EDS), nitrogen physisorption (BET), and temperature-programmed reduction (TPR). These techniques confirmed the formation of the expected phases, characterized the morphology of the materials, and provided insights for defining catalytic evaluation parameters. The catalytic performance was evaluated through CH₄ and CO₂ conversion, reactant deactivation analysis, H₂ yield, and the H₂/CO ratio. Post-reaction samples were analyzed by XRD, SEM, and thermogravimetry (TG) to investigate carbon deposition. The results indicated partial substitution of calcium for lanthanum in the doped perovskite structures, according to the stoichiometric proportions used. TPR analysis revealed that calcium doping increased the reduction temperature of the catalysts, making the activation process more difficult, as confirmed by the catalytic evaluation: the catalyst doped with 25% calcium activated after 2 hours of reaction, while the catalyst doped with 50% calcium required 6 hours. After activation, both catalysts exhibited activity and stability comparable to that of the standard LaNiO₃ catalyst. Additionally, analyses indicated a significant absence of coke formation in the materials. These results suggest that calcium doping in LaNiO₃ perovskites is a promising strategy for improving stability in dry reforming of methane, although further studies are needed to optimize catalytic performance and assess material durability under prolonged operating conditions.

COMMITTEE MEMBERS:
Presidente - 349770 - DULCE MARIA DE ARAUJO MELO
Externo à Instituição - TIAGO ROBERTO DA COSTA - IFRN
Externo à Instituição - VÍTOR RODRIGO DE MELO E MELO - UFRN