Banca de DEFESA: FELIPE MARINHO FERNANDES

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : FELIPE MARINHO FERNANDES
DATA : 14/03/2019
HORA: 09:00
LOCAL: Sala 50, Pavilhão de Química - ICE
TÍTULO:

Theoretical Description of the Chemical Loop Reform Reaction 

PALAVRAS-CHAVES:

Reform reaction, iron oxides

PÁGINAS: 92
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Físico-Química
ESPECIALIDADE: Química Teórica
RESUMO:

The world energy matrix is mostly dependent on petroleum-based fuels. However, this pattern leads to several negative impacts mainly on the Earth's atmosphere. In addition, it is well known that, following the current rate of oil consumption, these inputs must end in less than 50 years. Therefore, the adoption of a sustainable energy matrix is fundamental for the future. Hydrogen is an excellent candidate to take over the reins of this energy matrix. When burned, it produces water as a product (considerably less harmful than the products of combustion of fossil fuels), and in car engines, for example, are up to three times more efficient than gasoline. There are a few ways, however, to produce hydrogen. The most usual, at present, are steam reform processes. However, a process has been revisited: steam reforming through chemical cycles. This is because, due to nanotechnology, iron oxide-based nanocatalysts were made possible by increasing the resistance of these important participants in the reactions involved in the process and thus making this method of hydrogen production synthesis possible. With this, we will approach with a theoretical bias the stage of reduction of the magnetite (chosen catalyst) in the catalytic reform to steam via chemical cycles: CH4 + 4Fe3O4 CO2 + H2O + 12Fe0. For this, it was approached the magnetite, which is a mineral, solid at temperature and ambient pressure and has minimum formula Fe3O4 was approximated to a Fe12O16 cluster structure. Due to the magnetic properties of the mineral, the reaction stages were studied in three different electronic state levels: singlet, triplet and quintet.To date, the triplet multiplicity was observed as the ground state of the cluster study carried out that swept from a molecule up to four molecules of Fe3O4, where the triplet difference for singlet and quintet was at least 94 kcal / mol for the largest cluster for the BPW91 DFT with dual polarized LAV2P base (BPW91 / LAV2P **). The largest cluster, Fe12O16, was adopted as the cluster used in the steps with chemical reactions. To date, only results on the singlet multiplicity have been evaluated and a physical adsorption channel (fisistion) was proposed with two distinct fisistion products, having energy differences between them of less than 5 kcal / mol, followed by an adsorption step (chemisorption), with five chemisorption products with a high energy dispersion value, all calculations performed at DFT level B3LYP with LAV2P ** base. Physical adsorption was related to chemical adsorption through a transition state that connected a fisistion product to a chemisorption product. This state was confirmed by a frequency calculation where an imaginary frequency of 1335.37i cm-1 was reported. In the future, it is intended to study the same paths in the two different multiplicities in order to compare which channel has the lowest energy. It will still be necessary to continue with the theoretical description to better understand this reaction channel and, with that, to contribute with the optimization of the process in order to better enable it.

MEMBROS DA BANCA:
Interno - 1716351 - GLAUCO FAVILLA BAUERFELDT
Interno - 1354432 - CLARISSA OLIVEIRA DA SILVA
Interno - 1115883 - ANTONIO MARQUES DA SILVA JUNIOR
Externo ao Programa - 1808284 - MARCIO SOARES PEREIRA
Externo à Instituição - VICTOR DE OLIVEIRA RODRIGUES - UFRJ
Externo à Instituição - THIAGO MESSIAS CARDOZO - UFRJ