The enhancement of the NO/carbon reduction reactions by carbon monoxide has
been demonstrated for carbons of widely varying nature (coal char, phenoli
c resin-derived char and graphite). The evidence supports enhancement of NO
reduction via a carbon-surface-catalyzed reaction such as NO + CO --> 1/2N
(2) + CO2. This reaction appears to be characterized by an activation energ
y of around 116 kJ/mol, and by zero order with respect to CO, in the range
of CO pressures examined here (up to order 500 ppm). This suggests that an
oxide stripping reaction, e.g., CO + C(O) --> CO2 + C*, cannot be invoked i
n its usual form, to explain the rate enhancement. The reaction appears to
be first order with respect to NO, at high temperatures and at NO concentra
tions of above roughly 100 ppm, but kinetic analysis is complicated by the
fact that the NO-carbon reaction itself does not have a unique order at low
temperatures. It is also shown that kinetic analysis can be greatly compli
cated in the presence of other oxidizing gases or surface oxides deposited
by these gases.