Studies On Gas-Phase Oxidation Of Nitric Oxide Using Ozone
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Date
2007-09
Authors
Abdul Patah, Abir
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Abstract
Emission of nitrogen oxides (NOx) such as nitric oxide and nitrogen
dioxide presents a significant problem in environmental pollution control. NOx is
difficult to remove in wet scrubbers because most of it is in the form of NO,
which has a very low in solubility properties. If NO could be converted to higher
oxidized states such as N02, HN02, and HN03, then these species could be
removed by wet scrubbing. Thus, the main aim of this work is to study the gasphase
oxidation reaction of nitric oxide using ozone. Experimental works were
carried out in a plug flow reactor at atmospheric pressure with reaction
temperatures varying from 30 to 300 °C, residence times ranging from 0 to 300s
and ratios of ozone to NO ranging from 0.5 to 1.5 were carried out. In addition,
a study is carried out with the presence of moisture in the inlet NO in order to
ascertain whether there is any effect of dominance of moisture on oxidation
reaction of NO with ozone.
A mathematical model is presented to describe this oxidation process
theoretically using Matlab programming software. The effect of factors namely
residence time, ratio of O:JNO and temperature on percentage conversion of
NO were studied using the model with the two sets of data. The simulation of
the model with rate equation of Atkinson showed that the conversion of NO
increased with residence time. However optimum for ratio of O:JNO and
temperature were observed at 1.0 and 200°C respectively. The results of
simulations of the model using data from Atkinson showed compatibility of data
with experimental results. A study was made for identification of parameters
ratio O:/NO and temperature for optimization of the traverse length/time. This
study showed a ratio of O:/NO of 1.5 and temperature of 200°C suited well for
optimum traverse length.
Design of Experiment (DOE) was used to assess the effects of
temperature, residence time and concentration ratio of O:/NO on the conversion
of NO. The yield of nitrogen dioxide was maximized by determining the optimum
conditions using response surface methodology. The optimum reaction
conditions were reaction temperature of 224°C, residence time of 158s and
concentration ratio of O:/NO of 1 .4 which give the percentage conversion of NO
of 98%.
Description
Keywords
Oxidation Of Nitric Oxide , Using Ozone