In:
MRS Proceedings, Springer Science and Business Media LLC, Vol. 111 ( 1987)
Abstract:
A series of iron oxide-chromia on alumina and iron oxide on magnesia materials were made by the aerogel process. These materials had high surface areas (300 to 700 m 2 /g) and demonstrated good activity for the selective reduction of nitric oxide by ammonia. A combination of 4 parts Fe to 1 Part Cr gave the best catalyst for the reaction. Fe-Cr to alumina ratios were varied from 0.1 to 0.4. Activity per unit weight increased with increasing Fe-Cr/A1 2 O 3 ratios, however, activity per unit Fe-Cr favored the lower Fe-Cr to alumina ratios. The fresh material from the autoclave was found reduced (Fe 3 O 4 ) and initially had poor activity for the selective reduction of nitric oxide by ammonia (525 ppm NO & 525 ppm NH 3 in air feed conditions). However, after several testing cycles, in which the catalyst was in continuous contact with oxygen (as air), activity improved dramatically. Upon removal from the reactor the material had a distinct color change (from brown to reddish brown) and magnetic properties were lost. This suggests that Fe 2 O 3 is part of the active site for the selective reduction of nitric oxide by ammonia. At higher temperatures activity decreased because of a competing reaction, ammonia oxidation to nitric oxide.
Type of Medium:
Online Resource
ISSN:
0272-9172
,
1946-4274
DOI:
10.1557/PROC-111-359
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
1987
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