Banca de DEFESA: WANDSON LUKAS DO NASCIMENTO AMORIM

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : WANDSON LUKAS DO NASCIMENTO AMORIM
DATE: 16/11/2022
TIME: 14:00
LOCAL: Por participação remota em https://conferenciaweb.rnp.br/webconf/dalmo-2
TITLE:

SYNTHESIS OF HETEROGENEOUS CATALYSTS BASED ON METAL-ORGANIC FRAMEWORKS (MOFs) MODIFIED WITH IRON FOR APPLICATION IN THE SELECTIVE OXIDATION OF ALKANES

PAGES: 75
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Cinética Química e Catálise
SUMMARY:

The selective oxidation of alkanes is one of the main challenges of Catalysis and Organic Chemistry today. The C-H bonds present in these molecules demand high activation energies and the products formed to have greater reactivity, which directly affects the selectivity in oxidative processes. Cyclohexane is an important alkane for the polymer industry such as nylon-6 and nylon-6,6. The oxidation of this compound leads to the formation of two main products, cyclohexanol and cyclohexanone, commonly called KA oil (KA oil), which are industrially produced using homogeneous catalysts based on cobalt salts and boric acid under high pressure. between 10 and 20 bar and temperatures between 140 and 180 °C. The conversion rates are in the order of 7% with low yields, however, with high selectivity. One of the ways to optimize this process can happen through the heterogenization of the catalyst. In this sense, a new class of materials, the Metal-Organic Frameworks (MOFs), have drawn attention to the construction of heterogeneous catalysts according to the desired application, as they present crystallinity, high porosity, large specific surface area and chemical, thermal and structural stability. In this work, MOF UiO-66(Zr) was used to support active Fe species to catalyze the selective oxidation of cyclohexane with hydrogen peroxide (50% w/w). The prepared materials were evaluated by specific surface area and porosity analysis (ASAP), X-ray powder diffraction (PXRD), X-ray excited photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy coupled with X-ray energy dispersive spectroscopy (SEM-EDS) and thermogravimetric analysis (TGA). The catalytic activity was evaluated under mild reaction conditions at atmospheric pressure and 40°C with magnetic stirring at 1000 rpm for 2 h with a substrate:oxidant ratio equal to 1:1 and the products were quantified by gas chromatography with a flame ionization detector (GC-FID). The results indicate that both MOF and the catalyst – Fe(III)-UiO-66(Zr) – show structural and thermal stability after post-synthesis processes and reaction cycles. Additionally, the FTIR data showed that the catalyst may not have chemical stability, as there was a reduction in the intensity of one of the characteristic bands after application in reaction. The specific surface area of the MOF was 1621 m²/g and of the catalyst 1347 m²/g, which indicates that Fe was incorporated into the MOF, and this result corroborates the semiquantitative analysis performed by EDX which demonstrated the presence of Fe(III), about 1.4%, in catalytic amounts and well distributed on the surface of the support. The results of the catalytic tests showed that the catalyst was active with high conversion of cyclohexane with yields in the order of 7%, however, with limited selectivity for cyclohexanol. In conclusion, the leaching tests showed that the catalytic system has mostly heterogeneous character, because, after hot filtration of the catalyst, there was a reduction in the production of cyclohexanol over time, proving that this process occurs with greater intensity in the presence of the catalyst.

BANKING MEMBERS:
Presidente - Interno ao Programa - 1762430 - DALMO MANDELLI
Membro Titular - Examinador(a) Interno ao Programa - 1601156 - WAGNER ALVES CARVALHO
Membro Titular - Examinador(a) Externo à Instituição - MARCO ANDRÉ FRAGA - INT
Membro Suplente - Examinador(a) Externo à Instituição - FABIANE DE JESUS TRINDADE
Membro Suplente - Examinador(a) Externo à Instituição - ESTEVAM VITORIO SPINACÉ