ABSTRACT
Acknowledgments .............................................................................................................. 229
References .......................................................................................................................... 230
The destruction or removal of nitrogen oxides (DeNOx process) is a very important issue in
environmental catalysis [1, 2]. Nitrogen oxides (NO, NO2, and N2O) are formed during
combustion reactions in automotive engines and industrial plants when the nitrogen present
in air-fuel mixtures reacts with oxygen [1]. In addition, the burning of oil-derived fuels with
N-containing impurities [3] also leads to the formation of nitrogen oxides [1, 2]. Subsequent
release of the NOx combustion products into the atmosphere contributes to the generation of
smog and constitutes a serious health hazard for the respiratory system [1]. Furthermore, in the
air, the NOx species undergo oxidation and react with water, producing acid rain that corrodes
monuments and kills vegetation [1]. Thus, to reduce environmental pollution, it is necessary to
use catalysts or sorbents to remove or trap the nitrogen oxides before they reach the atmos-
phere. Although DeNOx operations have been a major concern for the last three decades,
recently, research in this area has intensified [2]. In part, this is motivated by the fact that there is
evidence that emission of the noxious NOx vapors into the atmosphere has increased world-
wide [4]. New and more stringent environmental regulations emphasize the need for more
efficient catalysts or sorbents for preventing or controlling NOx emissions [2, 4]. There is still no
universally acceptable solution to this major problem in environmental chemistry [2-7].
