Banca de QUALIFICAÇÃO: FELIPE MARINHO FERNANDES

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : FELIPE MARINHO FERNANDES
DATE: 29/08/2023
TIME: 09:00
LOCAL: https://meet.google.com/ujz-kmyp-upo
TITLE:

Catalytic Steam Reforming Via Chemical Cycles for Hydrogen Production

KEY WORDS:

Catalutic steam reforming, Reaction chemical cycles, Iron oxides, DFT, Periodic Boundary Conditions

PAGES: 20
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Química Teórica
SUMMARY:

The yield of energy is, nowadays, one of the great challenges faced by humanity.
It is necessary, in this respect, to reconcile, simultaneously, good energy
efficiency and the greatest possible commitment to sustainability. In this way,
steam reforming via chemical cycles for the production of hydrogen emerges as
an excellent option, since it is capable of producing hydrogen in a pure stream,
in addition to producing, as a by-product, a stream of heated carbon dioxide gas,
which can be used as a thermal load to maintain the high temperatures required
for chemical reactions and to avoid the formation of NOx, as occurs in
conventional catalytic reforming. To produce hydrogen gas, it will be necessary
to use three different reactors - Fuel Reactor (FR), Steam Reactor (SR) and Air
Reactor (AR) -, in which the oxygen carrier will circulate, among them, in three
different states of oxidation: Fe2O3 à FeO à Fe3O4 à Fe2O3. This continues
with the addition of fuel based on some light hydrocarbon, such as methane, in
the FR, oxidizing it to CO2 and reducing the catalyst to FeO, which will be sent
to the SR reactor. In this reactor, there will be the reduction of water to hydrogen
gas and then the consequent oxidation of FeO to Fe3O4 will occur. After this step,
the catalyst is sent to the AR reactor to be regenerated to Fe2O3 and therefore
regenerated, it can carry out more cycles, producing more hydrogen gas. It is
worth noting that this procedure, which requires catalysis, has transition metal
oxides as strong candidates for this function, especially iron oxides, as they have
very interesting characteristics, such as: low toxicity, wide availability, relatively
low cost. In addition to having considerable conversion (compared to other
metallic catalysts) and high selectivity to produce hydrogen gas. However,
despite these advantages, the production of hydrogen by this method is still much
less advantageous than the conventional catalytic reforming, when considering
the economic point of view since the reforming technique via chemical cycles still
presents much lower yields. To improve this process, alternatives are sought that
can also be explored, such as the use of dopants such as lithium, potassium, and
sodium, in addition to the use of mixed catalysts such as TiO2/Fe2O3, which
promise to improve the reaction yield. chemical. Therefore, a better
understanding of the reactions involved in this process is required, since, in the
literature, there are still many divergences such as, for example, the activation
barriers of methane converting into hydrogen, ranging from 49 to 271 kJ/mol.
There is also the little-explored possibility of converting ethane, the second main
component of natural gas. Therefore, this project aims to seek a better
understanding of the reactions involved in these cyclic steps, adopting a
computational approach using the density functional theory and the formalism of
periodic boundary conditions. Therefore, it will be necessary to describe at PBE
level the crystalline solids of iron oxides (Fe2O3, FeO and Fe3O4), defining, for
them, the k-point mesh and the kinetic shear energy, as well as the magnetic
configuration of these compounds. In addition, it will be necessary to describe all
reactions through PBE calculations using ultrasoft pseudopotentials, in addition
to including dispersion corrections with the D3BJ method, all implemented in the
Quantum ESPRESSO (QE) program. Still, to characterize the localized potential
energy minima, it is necessary to calculate phonons, through the routine
implemented in QE. Still, you can connect the reagents to their products through
the CI-NEB interpolator also implemented in the program. Still, to carry out such
calculations, it will be necessary to submit a project at the National Laboratory of
Scientific Computing, Santos Dumont.

COMMITTEE MEMBERS:
Presidente - 1220404 - CARLOS MAURICIO RABELLO DE SANT ANNA
Externo à Instituição - GLADSON DE SOUZA MACHADO - UFRRJ
Externo à Instituição - LEONARDO BAPTISTA - UERJ