Russian Journal of Applied Chemistry, Vol. 76, No. 4, 2003, pp. 561 565. Translated from Zhurnal Prikladnoi Khimii, Vol. 76, No. 4, 2003,
pp. 582 585.
Original Russian Text Copyright
2003 by Grinevich, Ivanova, Kostrov.
CATALYSIS
Plasma-Enhanced Catalytic Oxidation of Carbon Monoxide
V. I. Grinevich, N. V. Ivanova, and V. V. Kostrov
Ivanov State University of Chemical Engineering, Ivanovo, Russia
Received October 9, 2002
Abstract Data on the kinetics of plasma-enhanced and plasma-enhanced catalytic oxidation of carbon(II)
oxide with IK-1-6 catalyst are presented. The influence exerted by IK-1-6 catalyst on the conversion of
carbon-containing components of the CO CO CH SO air gas mixture in barrier-discharge plasma is
2
4
2
analyzed.
Methods using fast-electron beams or low-tem-
perature plasma (barrier or corona discharge) to ini-
tiate oxidation are presently recognized as promising
methods for purification of exhaust gases of thermal
power plants and internal-combustion engines, with
the plasma activation being, as a rule, more advanta-
geous energetically [1]. Combining the action of non-
equilibrium plasma on the gas mixtures with the ac-
tivating properties of catalysts may lead to a decrease
in energy expenditure and increase in the process rate
and degree of conversion. However, data on the ki-
netics of plasma-enhanced catalytic oxidation, and all
the more, on their mechanisms, are scarce. Therefore,
a study of the conversion of the main components of
real exhaust gases or model gas mixtures in barrier-
discharge (BD) plasma and in a combined plasma-
enhanced catalytic process is a topical task.
between the electrodes were the same in all the ex-
periments (1.5 and 3 mm, respectively). The discharge
was excited with a high-voltage transformer (ac fre-
quency 50 Hz,) at a voltage varied within the range
12 16 kV. The discharge current was monitored with
an oscilloscope.
Plasma-enhanced catalytic processes were studied
with an IK-1-6 (V O5 K O/SiO ) commercial cat-
2
2
2
alyst [3]. The catalyst (grain size 1.0 1.6 mm) was
placed in the plasma zone and fixed there with flu-
oroplastic rings with holes for the gas mixture to flow.
The concentration of CO, CO , and CH in the initial
2
4
gas mixture and at the reactor outlet was monitored
chromatographically [4] (LKhM 80 chromatograph
with heat-conductivity detector, carrier gas helium),
and the SO2 concentration, photometrically, using
a standard procedure [5]. The gas flow rate was var-
3
1
The aim of this study was to analyze the processes
of plasma-enhanced catalytic oxidation of carbon
monoxide in various gas mixtures.
ied from 0.08 to 0.63 cm s , which corresponded
to 20 to 120 s of contact of the gas with the plasma.
The random error in measuring the CO, CO , and CH
2
4
concentrations in a set of runs was no more than 30%
at confidence probability of 0.95.
EXPERIMENTAL
One of parameters determining the kinetics of pro-
cesses occurring in BD plasma is the plasma dose
D (mA s cm ), related to the current density j and to
As test objects were chosen gas mixtures of com-
position (vol %): CO O He (CO 6, O 24, and He
2
2
2
7
0
0), CO CO SO air (CO 5.84, CO 0.16, and SO
2 2 2 2
the time
of contact between gas and plasma by
c
.10), and CO CO CH SO air (CO 0.74, CO 17,
2
4
2
2
SO 0.10, and CH 0.26). The initial gas mixture
2
4
D = j c.
was fed at a certain rate into the discharge cell, where
a barrier discharge was excited at atmospheric pres-
sure. The reactor was in the form of two coaxial cyl-
inders, one of which (outer) was made of molybde-
num glass (dielectric barrier), and the other (inner
electrode), of an aluminum alloy [2]. The thicknes-
ses of the dielectric layer (S-49 glass) and air layer
The plasma dose was varied within 0.1
2
2
.0 mA s cm .
It is known that use of BD leads to rather high de-
grees of carbon(II) oxide conversion in stoichiometric
mixtures with an oxidant [6]. Measurements of the
1
070-4272/03/7604-0561 $25.00 2003 MAIK Nauka/Interperiodica