Res. Chem. Intermed.
, Vol. 28, No. 5, pp. 409–417 (2002)
Ó
VSP 2002.
Also available online - www.vsppub.com
Modi cation of active carbon and zeolite as ammonia
separation materials for a new de-NO
x
process
with ammonia on-site synthesis
CHUN YI LIU and KEN-ICHI AIKA
¤
Department of Environmental Chemistry and Engineering, InterdisciplinaryGraduate
School of Science and Engineering, Tokyo Institute of Technology,
4259 Nagatsuta, Midori-ku, Yokohama, 226-8502, Japan
Received 20 September 2001; accepted 30 November 2001
Abstract—Ammonia adsorption and desorption behavior of surface treated active carbon (AC) and
ion-exchanged Y zeolite, as ammonia separation and storage materials for a new de-NO
x
process
with ammonia on-site synthesis, were studied. Surface oxidized AC adsorbed more ammonia than
non-treated AC due to ammonium ion formation. These materials were found to increase weak
adsorption of ammonia and to be useful for pressure swing adsorption. Transition metal ion exchanged
Y-zeolite adsorbed more ammonia (both weak and strong form) than Na Y-zeolite due to ammine
complex formation. These materials adsorb and desorb more ammonia than treated AC when used for
temperature swing adsorption.
INTRODUCTION
In the modern power plant, liquid ammonia is used as reducing agent for NO
x
removal. But the on-site cost of ammonia is more expensive than that at the
ammonia plant, because of the transfer and storage. The authors have proposed a
new de-NO
x
process equipped with ammonia on-site synthesis reactor (Fig. 1) [1].
This process involves three steps. In the rst step, ammonia is synthesized on a Ru
catalyst under pressure of 1.0 MPa. The ammonia pressure produced is expected to
be 40– 60 kPa. In the second step, ammonia is separated and stored by an adsorbent
at 298 – 323 K. Adsorbed ammonia is transferred to the next step by a pressure swing
adsorption (PSA) or temperature swing adsorption (TSA) method. In the third step,
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To whom correspondence should be addressed. E-mail: kenaika@chemenv.titech.ac.jp
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