Banca de DEFESA: JULIA VIEIRA DA SILVA BERNARDO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : JULIA VIEIRA DA SILVA BERNARDO
DATE: 17/04/2026
TIME: 14:00
LOCAL: a definir
TITLE:

MESOPOROUS SILICA-BASED MATERIALS AND CARBON REPLICAS FOR CO2 ADSORPTION AND CONVERSION.

KEY WORDS:

Mesoporous materials; Nickel; Adsorption; Methanation; CO₂.

PAGES: 160
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
SPECIALTY: Cerâmicos
SUMMARY:

In this work, mesoporous silica-based materials (SBA-15 and KIT-6) and their corresponding carbon replicas (CMK-3 and CMK-8) were synthesized aiming at CO₂ adsorption and conversion. The materials were used as supports for nickel impregnation, employed as the active phase for CO₂ hydrogenation to methane. Commercial activated carbons were also impregnated and characterized by comparison of structural and textural properties; among them, the material with the best properties (CA-BP-Ni) was selected for the catalytic methanation test. X-ray diffraction (XRD) confirmed the preservation of the ordered mesoporous structure after impregnation. N₂ adsorption/desorption isotherms exhibited type IV behavior for mesoporous silica and carbon materials, and type I for activated carbons, indicating their predominantly microporous nature. The supports exhibited high specific surface areas, with CMK-8 (1187 m² g⁻¹) and CMK-3 (1018 m² g⁻¹) standing out, while SBA-15 and KIT-6 showed areas approximately to 640 and 600 m² g⁻¹, respectively. After nickel impregnation, a decrease in the specific areas (13-30%) was observed, attributed to partial pore occupation by nickel, except for KIT-6. CO₂ adsorption tests demonstrated that adsorption capacity is directly related to specific surface area and pore accessibility, being more pronounced in materials with higher surface areas. Nickel impregnation caused a slight decrease in CO₂ uptake, indicating a minor contribution of the metallic phase to the adsorption process. Temperature-Programmed reduction (TPR) analyses revealed multiple reduction events with maximum temperatures between 336 and 485 °C, indicating varying metal–support interaction strengths. In CO₂ hydrogenation to methane, the SBA-15-Ni catalyst showed the highest average conversion (≈5.2%) and high methane selectivity (≈95%), with slight deactivation over 10 h of reaction. KIT-6-Ni showed lower conversion (≈3.6%) but greater stability over time. CMK-3-Ni presented low conversion (<1%) and lower methane selectivity, highlighting the influence of support nature on metal–support interaction and catalytic performance. Overall, the results demonstrate that structural and textural properties play a decisive role in both CO₂ adsorption and conversion, emphasizing the importance of structural control in the synthesis of catalysts for methanation.

COMMITTEE MEMBERS:
Presidente - 1308577 - SIBELE BERENICE CASTELLA PERGHER
Interno - 1350249 - RUBENS MARIBONDO DO NASCIMENTO
Externo ao Programa - ***.843.440-** - EDUARDO RIGOTI - UFRN
Externa à Instituição - ANNE GABRIELLA DIAS SANTOS - UERN