Catalysts for lean burn engine exhaust abatement
AssigneeThe Regents of the University of California
InventorsKevin C. Ott, Noline C. Clark, Mark T. Paffett
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Abstract
The present invention provides a process for catalytically reducing nitrogen oxides in an exhaust gas stream containing nitrogen oxides and a reductant material by contacting the gas stream under conditions effective to catalytically reduce the nitrogen oxides with a catalyst comprising a aluminum-silicate type material and a minor amount of a metal, the catalyst characterized as having sufficient catalytic activity so as to reduce the nitrogen oxides by at least 60 percent under temperatures within the range of from about 200° C. to about 400° C.
Claims17
A process for catalytically reducing nitrogen oxides in an exhaust gas stream containing nitrogen oxides and a reductant material comprising:
- contacting said gas stream under conditions effective to catalytically reduce said nitrogen oxides with a catalyst comprising an aluminum-silicate type material and a metal in an amount of up to about 0.1 weight percent based on total weight of catalyst, said catalyst characterized as having sufficient catalytic activity so as to reduce the nitrogen oxides by at least 60 percent under temperatures within the range of from about 200° C. to about 400° C.
A process for catalytically reducing nitrogen oxides in an exhaust gas stream containing nitrogen oxides and a reductant material comprising:
- contacting said gas stream under conditions effective to catalytically reduce said nitrogen oxides with a catalyst, the catalyst comprising an aluminum-silicate type material and a metal in an from about 0.1 weight percent to about 7.0 weight percent, the aluminum-silicate type material amount having been pretreated prior to contact with said exhaust gas stream by contact with a dilute solution of a material selected from the group consisting of ammonium fluoride, ammonium nitrate, ammonium chloride, nitric acid, hydrochloric acid, hydrofluoric and oxalic acid for a sufficient period of time followed by addition of a metal to said pre-treated ferrierite material to allow for catalytically reducing nitrogen oxides in an exhaust gas stream containing nitrogen oxides and a reductant material, said catalyst characterized as having sufficient catalytic activity so as to reduce the nitrogen oxides by at least 50 percent under temperatures within the range of from about 200° C. to about 600° C.
A composition of matter, useful in a process for catalytically reducing nitrogen oxides in an exhaust gas stream containing nitrogen oxides and a reductant material, comprising a zeolite material having undergone a pretreatment including contact with a dilute solution of a material selected from the group consisting of ammonium fluoride, ammonium nitrate, ammonium chloride, nitric acid, hydrochloric acid, hydrofluoric and oxalic acid for a sufficient period of time followed by addition of a metal to said pretreated ferrierite material to allow for catalytically reducing nitrogen oxides in an exhaust gas stream containing nitrogen oxides and a reductant material by at least 60 percent under temperatures within the range of from about 200° C. to about 600° C.
A composition of matter, useful in a process for catalytically reducing nitrogen oxides in an exhaust gas stream containing nitrogen oxides and a reductant material, comprising a zeolite material including a metal in an amount of up to about 0.1 weight percent based on total weight of zeolite and metal, said composition characterized by catalytically reducing nitrogen oxides in an exhaust gas stream containing nitrogen oxides and a reductant material by at least 60 percent under temperatures within the range of from about 200° C. to about 400° C.
Dependencies are inferred from the claim text.