Chemistry of inorganic compounds – Modifying or removing component of normally gaseous mixture – Nitrogen or nitrogenous component
Patent
1995-04-27
2000-06-27
Lewis, Michael
Chemistry of inorganic compounds
Modifying or removing component of normally gaseous mixture
Nitrogen or nitrogenous component
502 60, 502 64, 502 66, 502 71, 502 74, 502 78, 502 79, 502 77, 4232135, B01J 800
Patent
active
060803770
ABSTRACT:
A method for reducing gaseous nitrogen oxides present in a gas stream by reaction with a reductant species is practiced by flowing the gas stream under lean NO.sub.X -reducing conditions in contact with a catalytic material containing a catalytically effective amount of a catalytic species, e.g., a platinum group metal, and a reductant storage material, e.g., a zeolite, effective for storing reductant species for reaction with NO.sub.X, and providing an intermittent supply of the reductant to the gas stream. The catalytic material may be prepared in any manner, but one method is to incorporate a catalytically effective amount of the platinum into a template-bearing molecular sieve material, preferably ZSM-5 zeolite, to hinder the platinum from being incorporated into the pores of the molecular sieve material, and then calcining the molecular sieve material, whereby the template is removed from the molecular sieve material after the platinum is incorporated therein. Another method is to add a blocking agent to the molecular sieve material, then incorporate the platinum therein, and then calcine the material to remove the blocking agent. The catalytic material may contain less than about two percent by weight of zeolite plus platinum, e.g., less than about 0.5%, or from about 0.025% to 0.1% or 0.2% platinum.
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Deeba Michel
Farrauto Robert J.
Feeley Jennifer S.
Dunn Jr. Thomas G.
Engelhard Corporation
Lewis Michael
Negin R. A.
Shatynski T. J.
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