Banca de QUALIFICAÇÃO: WANDSON LUKAS DO NASCIMENTO AMORIM
Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.STUDENT : WANDSON LUKAS DO NASCIMENTO AMORIM
DATE: 28/09/2022
TIME: 14:00
LOCAL: Por participação remota - 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 LIGHT ALKANES
PAGES: 22
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Cinética Química e Catálise
SUMMARY:
The selective oxidation of light alkanes is one of the main challenges of Catalysis and Organic Chemistry today. The C-H bonds 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 metallic boric acid under pressures between 10 and 20 bar and temperatures between 140 and 180 °C. However, conversion rates are on the order of 7% with low yields and 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 and 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 catalyse the selective oxidation of cyclohexane with hydrogen peroxide (50% w/w). The synthesized materials were evaluated by specific surface area and porosity analysis (SAPA), powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy coupled to energy dispersive spectroscopy of X-rays (SEM-EDS), and thermogravimetric and differential thermogravimetric analysis (TGA-DTG). 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 might 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 that of the catalyst 1347 m2/g, which indicates that Fe was incorporated into the MOF, and this result corroborates the semiquantitative analysis performed by EDS which demonstrated the presence of Fe, about 1.4%, in catalytic amounts and with good distribution. The results of the catalytic tests showed that the catalyst was active with high conversion of cyclohexane with yields comparable to industrial ones, however, with low selectivity for KA oil. In conclusion, the leaching tests showed that the catalytic system is heterogeneous, since, after hot filtration, the yield reached a plateau in the kinetic curves.
BANKING MEMBERS:
Presidente - Interno ao Programa - 1762430 - DALMO MANDELLI
Membro Titular - Examinador(a) Externo à Instituição - MARCO ANDRÉ FRAGA - INT
Membro Titular - Examinador(a) Externo à Instituição - ESTEVAM VITORIO SPINACÉ
Membro Suplente - Examinador(a) Externo à Instituição - LUANA DOS SANTOS ANDRADE
Membro Suplente - Examinador(a) Externo à Instituição - FABIANE DE JESUS TRINDADE