| Summary: | 碩士 === 元智工學院 === 化學工程學系 === 84 === The adsorption of oxygen, carbon monoxide, nitrous oxide and
nitric oxide overgold foil were studied by temperature
programmed desorption (TPD) under ultra vacuum (UHV)
environment. The uptaje of oxygen and carbon monoxide on the
goldfoil surface at 323K were lower than the detecting limit of
the instrument we used. Although the gold surface contains
cobalt, rhodium and titanium or theiroxide was not significantly
enhanced. Nitrous oxide could be adsorbed on gold foil only at
very high dosing (360L) condition, and this is considered as an
activated adsorption process. As to the nitric oxide adsorption
study, there was one first-order desorption peakof nitric oxide
from gold foil surface between 270K and 500K. The desorption
activation energy, Ed, is approxmately 22kcal/mole when
analyzed by Redhead method. The
kinetic study of nitric oxide reduction by carbon monoxide
showed that thepretreatment condition can significantly afect
the catalytic activity of Au/ TiO2 catalyst. Among the
different pretreatment conditions tested, The high temperature
reduction/ calcination/ low temperature reduction (HTR/C/LTR)
pretreatment procedure was found to provide the hightest
activity, which is 3 times higher than those pretreated with
only HTR or HTR/C, and is an order higher than those
pretreated with only C or LTR procedure. The main reaction
products were nitrous oxide and carbon dioxide at lower
temperature range ( 323~423K) but nitrogen and carbon dioxide
were found to occure at higher temperature. The catalytic
activity of Au/TiO2(HTR/C/LTR) depended on temperature,
and had a minimum at 523K; an Arrhenius dependency was followed
for temperature higher than 523K, but a slow decreasing was
observed form 323 to 523K
|
|---|
