ammonia to nitrogen (>90%) by -Al2O3-supported Ni in selective
catalytic oxidation processes. Furthermore, Wang et al.
[15], who developed Ni-based catalysts for fuel gas oxidation
from biomass gasification, found fresh Ni-based catalysts to be
more active at lower temperature for the decomposition process
of ammonia, and the partial pressure of hydrogen in the flue
gas was a key factor to model ammonia oxidation. Liang [18]
studied ammonia oxidation in a fixed-bed microreactor in the
temperature range of 600–750 ◦C at GHSV= 1800–3600 h−1.
He observed that the conversion of ammonia reached 98.7 and
99.8% on nitrided MoNx/-Al2O3 and NiMoNy/-Al2O3 catalysts,
respectively. Olofsson et al. [19] have demonstrated that
excellent catalytic conversion of ammonia for nitrogen formation
and by -Al2O3-supported Pt/CuO in selective catalytic
oxidation processes. Among these, Schmidt-Szałowski [14] also
published a paper covering a hypothetical model to explain the
effect, the activity, and the selectivity in ammonia oxidation of
the cobalt oxide catalyst’s macrostructure on its properties.
As concerns reaction kinetic model, Lou [20] used a catalyst
composed of Pt, Ni and Cr alloy of foam type to study
the kinetics of catalytic incineration of butanone and toluene.
He found that the Mars and van Krevelen model was suitable to
describe the catalytic incineration of those volatile organic compounds
(VOCs). Lou [21] used a Pt/Al2O3 alloy catalyst to study
the kinetics of catalytic incineration of trichloromethane. He
adopted power-rate law kinetics and found that the reaction was
first-order in trichloromethane concentration and the activation
energy was 16.2 kcal/mol. Lou [22] also used a 0.05% Pt/Ni/Cr
alloy catalyst to study the kinetics of catalytic incineration of
trichloromethane. He found that the Mars and van Krevelen
model was suitable to describe the catalytic incineration of these
VOCs. Gangwal [23] used a 0.1% Pt, 3% Ni/-Al2O3 catalyst to
study the kinetics of deep catalytic oxidation with n-hexane and
benzene. They found that the Mars and van Krevelen model was
favorable to explain the catalytic combustion of a binary mixture
at temperature ranging from 160 to 360 ◦C. Nitrogen compounds
have been shown the similar manner, which were reversible
inhibitors to the catalyst [24]. However, the kinetic studies of
catalytic oxidation of NH3 on metal composite catalysts have
not been thoroughly investigated.
In this study, we investigate the nature of the adsorbed
species formed on the catalyst surface using an interpretation
of the kinetic data. Various kinetic models, including the
power-rate law, the Mars and van Krevelen model, and the
Langmuir–Hinshelwood model were evaluated in driving the
rate expression for NH3 oxidation. Hence, we sought to study
the activity of the nanoscale copper-cerium bimetallic catalyst
on oxidation of ammonia at various parameters and the kinetic
behavior of ammonia removal in the effluent stream. Our results
can provide valuable information for designing and treating an
ammonia-related system.
2. Materials