Banca de DEFESA: PEDRO PAULO LINHARES FERREIRA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : PEDRO PAULO LINHARES FERREIRA
DATE: 10/10/2022
TIME: 10:00
LOCAL: Auditório do CCET
TITLE:

Effect of Mn doping on MgAl2O4 spinel, heat treatment and addition of Aloe Vera on the synthesis of Carbon Nanotubes.

KEY WORDS:

carbon nanotubes, catalysts, green synthesis, aloe vera, spinel

PAGES: 106
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUMMARY:

Discovered in the mid-1990s, carbon nanotubes (CNTs) have special properties that expand their range of applications. CNTs can be produced from the decomposition reaction of methane in the presence of catalysts. However, the quality and quantity of CNTs produced strongly depends on the structure and properties of the catalysts. Thus, the objective of this thesis was to evaluate the relationship of the synthesis parameters of Mn-doped Ni catalysts in MgAl2O4, obtained using the green extract of Aloe Vera for the production of carbon nanotubes. For that, the supports of the catalysts were synthesized via microwave combustion, achieving two routes. The first was using only water; and the second using Aloe Vera as a chelating agent. Both routes had the objective of doping Mn ions in the A and B sites of MgAl2O4 for the evaluation of its characteristics. From the synthesized support, part was subjected to calcination at 900 °C for 3 h and part remained without heat treatment. Then, the materials were impregnated with 50% nickel and subjected to heat treatment (550 °C/3h). The formed catalyst was taken to the catalytic unit for activation and then to the synthesis of carbon nanotubes. The supports were characterized by X-ray diffraction (XRD). The catalysts were also subjected to XRD and thermal analysis (TG). The nanotubes were characterized by Raman, MEV-FEG and TG. XRD results indicated that the supports were replaced with the ion in different proportions, as well as the same analysis showed successful nickel impregnation. The CNTs along with the catalysts were analyzed by Raman spectroscopy, thermal analysis (TG) and scanning electron microscopy (SEM). The Raman results showed the formation of carbon nanotubes in all catalysts, with a GI/ID ratio > 1, indicating a crystallinity of the material formed. The relationship between the results of thermal analysis (TG) and Raman spectroscopy indicates that the nickel catalyst impregnated in MgAl2O4 with Mn2+ substituted in the A site, synthesized using Aloe Vera and calcined at 900 °C (Ni/Mn-SAAV900) produced less defective CNT's (GI/ID = 1.42), but with lower CNT production (4%p). In contrast, the nickel catalyst impregnated in MgAl2O4 with Mn2+ substituted in the B site, synthesized using Aloe Vera and calcined at 900 °C (Ni/Mn-SBAV900) showed a GI/ID ratio = 0.77, revealing more defective NTC's , but with a little more than twice as many NTC's formed. The micrographs corroborated the other analyses, indicating the formation of carbon nanotubes. The methodology adopted using green synthesis proved to be a way to produce carbon nanotubes.

COMMITTEE MEMBERS:
Presidente - 349770 - DULCE MARIA DE ARAUJO MELO
Externa ao Programa - 1979301 - RENATA MARTINS BRAGA - UFRNExterno ao Programa - 3304576 - RODOLFO LUIZ BEZERRA DE ARAÚJO MEDEIROS - UFRNExterno à Instituição - DENER DA SILVA ALBUQUERQUE - IFRN
Externo à Instituição - GILVAN PEREIRA DE FIGUEREDO - IFMA