Chemistry of inorganic compounds – Modifying or removing component of normally gaseous mixture – Mixture is exhaust from internal-combustion engine
Patent
1991-10-07
1993-01-05
Heller, Gregory A.
Chemistry of inorganic compounds
Modifying or removing component of normally gaseous mixture
Mixture is exhaust from internal-combustion engine
423239, B01J 802, C01B 2100
Patent
active
051768879
ABSTRACT:
A three-way catalyst system for treating the exhaust stream of a compressed natural gas (CNG) fueled engine operating slightly rich of stoichiometry, the said catalyst system providing high conversions and low light-off temperature for the remnoval of HC, CO, and NO.sub.x. A high surface area gamma alumina support is impregnated with an intimate mixture of 0.2-30% Pd and 0.5-20% La.sub.2 O.sub.3, the Pd being in crystalline form with a particle size in the range of 5.500 angstroms.
A method of making such catalyst system comprising sequentially impregnating a high surface area gamma alumina support with lanthana and palladium by incipient wetness techniques, such techniques comprising the procedure of contacting alumina first with a lanthanum nitrate solution of desired concentration to obtain 0.5-20% lanthana, contacting the lanthana impregnated alumina with a palladium nitrate solution of desired concentration to obtain a 0.2-30% palladium content in the catalyst, each of said steps being separated by drying and calcination.
A method of treating exhaust gas from a CNG fueled engine with the catalyst system described above, comprising: (a) operating said engine at slightly rich of stoichiometry; (b) exposing such catalyst to the exhaust gases in the range of 400.degree.-750.degree. C. and at a space velocity in the range of 0-100 K hr.sup.-1, said exhaust gas being converted at an efficiency greater than 90% for each of NO, CO, and CH.sub.4.
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Chattha Mohinder S.
Subramanian Somasundaram
Watkins William L. H.
Ford Motor Company
Heller Gregory A.
Malleck Joseph W.
May Roger L.
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