Nitrogen oxides (NOx) are formed during the combustion of coal and oth
er fuels. The Clean Air Act Amendments of 1990 require reductions in N
Ox emission by all industrial processes. In this NOx abatement process
, NOx in flue gas are adsorbed by a carbon adsorbent and then reduced
by carbon to nitrogen and carbon oxides with microwave energy. Six car
bon adsorbents were tested in this study to investigate the effects of
the microwave treatment on the NOx adsorption capacity and rate. The
surface areas of FMC calcined char and FMC cake increased from about 1
00 m(2)/g to around 800 m(2)/g. This is due to the carbon consumption
in the microwave-induced NOx reduction reactions. Through increasing t
he internal surface area and nitrogen content, the microwave treatment
improved the NOx adsorption capacity and rate for all carbon adsorben
ts, except the commercial activated carbon. The FMC calcined char show
ed the best improvement in NOx adsorption capacity and rate by microwa
ve regenerations and was thus studied further to obtain the mechanisms
of NOx adsorption on char and their reduction in the microwave energy
held. The experimental results show that in the presence of oxygen an
d moisture, NO is converted to NO2 and HNO3 on carbon surfaces. The NO
x adsorbed on carbon adsorbents can be reduced using microwave energy
with the product gas at room temperature. Nearly 90% of NOx adsorbed o
n FMC calcined char is reduced in this process.