US 5,589,147 AGranted

Catalytic system for the reducton of nitrogen oxides

AssigneeMobil Oil Corporation

InventorsMaria D. Farnos, John P. McWilliams, Sanjay B. Sharma, David S. Shihabi

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Abstract

There is presented a process for the treatment of exhaust gas, which process uses a specially prepared catalyst composition, for the selective catalytic reduction of NO.sub.x contained in the exhaust gas. An embodiment of the process of this invention comprises a catalytic stage to selectively catalytically reduce NO.sub.x over a catalyst composition comprising a molecular sieve that has been treated with a metal in a way effective to maximize metal dispersion. The catalyst of this invention typically comprises a silica, titania, or zirconia binder, e.g. a binder including a high molecular weight, hydroxyl functional silicone resin. The catalyst of this invention may be formed into a desired shape, e.g., by extrusion, and finished in a humidified atmosphere after forming.

Claims11

Dependent claims

A method for treating an exhaust gas comprising NO.sub.x and ammonia, said method comprising directing the exhaust gas along with a source of oxygen over a catalyst under treating conditions effective for the selective catalytic reduction of NO.sub.x ;

said catalyst comprising a molecular sieve which has been physically mixed with a metal and a binder or a binder precursor under contacting conditions effective to produce a metal loading of about 0.01 wt. % to about 5 wt. % with reference to the molecular sieve;
said molecular sieve being at least one selected from the group consisting of ZSM-5, ZSM-11, ZSM-12, ZSM-21, ZSM-22, ZSM-23, ZSM-35, ZSM-38, ZSM-48, ZSM-58, and combinations thereof;
said binder or binder precursor comprising at least one selected from the group consisting of titania, zirconia, and silica;
said process further comprising finished said catalyst in a humidified atmosphere under conditions effective to produce improved hydrothermal stability;
the metal being selected from the group consisting of at least one of the Groups of the Periodic Table of IIIA, IB, IIB, VA, VIA, VIIA, VIIIA, and combinations thereof.

2 more elements

Dependencies are inferred from the claim text.