@PhDThesis{Okamoto:2015:DeMaCa,
author = "Okamoto, Sayuri",
title = "Desenvolvimento de materiais catal{\'{\i}}ticos para
decomposi{\c{c}}{\~a}o do N2O para aplica{\c{c}}{\~o}es
aeroespaciais",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2015",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2015-11-25",
keywords = "{\'o}xidos mistos, catalisadores m{\'a}ssicos,
decomposi{\c{c}}{\~a}o de N2O, propulsor, mixed oxides, bulk
catalysts, N2O decomposition, thruster.",
abstract = "Este trabalho teve como objetivo o desenvolvimento de um
catalisador m{\'a}ssico {\`a} base de {\'o}xidos de cobalto,
mangan{\^e}s e alum{\'{\i}}nio, com estrutura do tipo
espin{\'e}lio, capaz de decompor espontaneamente o {\'o}xido
nitroso (N\$_{2}\$O) para emprego em um propulsor de 2 N,
buscando sempre temperaturas de igni{\c{c}}{\~a}o da
rea{\c{c}}{\~a}o inferiores a 773 K. Inicialmente foram
estudadas as altera{\c{c}}{\~o}es nas propriedades
f{\'{\i}}sico-qu{\'{\i}}micas e texturais dos pellets obtidos,
a partir de diversas t{\'e}cnicas de s{\'{\i}}nteses destes
materiais, tais como: tratamento hidrot{\'e}rmico,
coprecipita{\c{c}}{\~a}o, sol-gel e sol-combust{\~a}o. O
m{\'e}todo de s{\'{\i}}ntese por coprecipita{\c{c}}{\~a}o,
com emprego de dois agentes precipitantes (KOH e
K\$_{2}\$CO\$_{3}\$), foi o {\'u}nico que gerou um material
mold{\'a}vel. Foi tamb{\'e}m estudada a influ{\^e}ncia da
varia{\c{c}}{\~a}o da raz{\~a}o molar dos c{\'a}tions
met{\'a}licos (Co:Mn:Al) na decomposi{\c{c}}{\~a}o do
N\$_{2}\$O. Testes de bancada mostraram que a raz{\~a}o molar
4:1:1 foi aquela que apresentou a maior atividade
catal{\'{\i}}tica, devida a presen{\c{c}}a do par redox
Co\$^{2+}\$/Co\$^{3+}\$. Os materiais foram caracterizados por
Difratometria de Raios X, Adsor{\c{c}}{\~a}o de Nitrog{\^e}nio,
Dessor{\c{c}}{\~a}o de N\$_{2}\$O a Temperatura Programada,
Espectrometria Fotoeletr{\^o}nica de Raios X e Termogravimetria.
Posteriormente, foram otimizadas as dimens{\~o}es
geom{\'e}tricas do leito catal{\'{\i}}tico do micropropulsor de
2 N, empregando a metodologia de Planejamento de Experimentos.
Para tanto, foi feito um propulsor em m{\'o}dulos, com diferentes
geometrias do leito catal{\'{\i}}tico, carregado com o material
contendo a raz{\~a}o molar 4:1:1. Finalmente, foi fabricado um
micropropulsor com empuxo te{\'o}rico de 2 N, onde foram
efetuadas campanhas de testes compostas de tiros
cont{\'{\i}}nuos e pulsados, sendo monitorado o empuxo, a
press{\~a}o e a temperatura do sistema. Os resultados obtidos com
o catalisador 4Co1Mn1Al (4:1:1) neste propulsor, foram comparados
com os do catalisador (5\%
Rh\$_{2}\$O\$_{3}\$/Al\$_{2}\$O\$_{3}\$) tradicionalmente
empregado na decomposi{\c{c}}{\~a}o do N\$_{2}\$O. O
catalisador 4Co1Mn1Al apresentou maior atividade nesta
rea{\c{c}}{\~a}o, exibindo uma efici{\^e}ncia da velocidade
caracter{\'{\i}}stica em torno de 97,5\%, valor este bem
superior {\`a}quele obtido pelo catalisador tradicional de
62,5\%. ABSTRACT: The objective of this work was the development
of bulk catalyst based on cobalt, manganese and aluminium oxide
with spinel structure for nitrous oxide decomposition reaction
applied to microthruster of 2 N with ignition temperature less
than 773 K. Initially were studied modification on
physical-chemical and textural properties on obtained pellets
using a variety of synthesis methods as hydrothermal,
coprecipitation, sol-gel and sol-combustion. Only the
coprecipitation method using two different precipitation agents
(KOH and K\$_{2}\$CO\$_{3}\$) allowed conformable materials.
Later, the influence of different molar ratio of metallic cations
(Co:Mn:Al) was investigated. In laboratory scale tests the molar
ratio of 4:1:1 presented better catalytic activity and presented
redox par Co\$^{2+}\$/Co\$^{3+}\$ on its surface composition.
All the materials were characterized using X-ray diffraction,
nitrogen adsorption, nitrous oxide desorption in programmed
temperature, X-ray photoeletronic emission spectrometry and
thermogravimmetry technics. The catalytic chamber dimensions were
optimized using Design of Experiments methods. For this purpose,
modular thrusters with different geometries containing molar ratio
4:1:1 were used. Finally, a microthruster with theoretical thrust
of 2 N was manufactured where all the tests campaign where
performed. This campaign was composed of continuous and pulsed
fires monitoring pressure, thrust and temperatures of the system.
The tests results obtained for 4Co1Mn1Al (4:1:1) using this
microthruster were compared with one employing 5\%
Rh\$_{2}\$O\$_{3}\$/Al\$_{2}\$O\$_{3}\$, a traditional
catalyst used for nitrous oxide decomposition. The exhaust
characteristic velocity efficiency for 4Co1Mn1Al was 97.5\% which
is superior of the value obtained for 5\%
Rh\$_{2}\$O\$_{3}\$/Al\$_{2}\$O\$_{3}\$ of 62.5\%.",
committee = "Vieira, Ricardo (presidente/orientador) and Soares Neto,
Tur{\'{\i}}bio Gomes and Mineiro, S{\'e}rgio Luiz and Bastos,
Luiz Claudio Antunes and Cortez, Gilberto Garcia",
copyholder = "SID/SCD",
englishtitle = "The development of catalytic materials for N2O decomposition
reaction for aerospace purpose",
language = "pt",
pages = "125",
ibi = "8JMKD3MGP3W34P/3KFLBBP",
url = "http://urlib.net/ibi/8JMKD3MGP3W34P/3KFLBBP",
targetfile = "publicacao.pdf",
urlaccessdate = "27 abr. 2024"
}