Catalyst system and method for the reduction of NOx

A catalyst system for the reduction of NOx comprising:

• a catalyst comprising (i) a metal oxide catalyst support comprising alumina, (ii) a catalytic metal oxide comprising at least one of gallium oxide or silver oxide in the range of from about 1 mole % to about 31 mole % and (iii) a promoting metal or combination of promoting metals selected from the group consisting of silver, cobalt, molybdenum, tungsten, indium, bismuth, indium and tungsten, silver and cobalt, indium and molybdenum, indium and silver, bismuth and silver, bismuth and indium, and molybdenum and silver in the range of from about 1 mole % to about 31 mole %;
• a gas stream comprising (A) water in the range of from about 1 mole % to about 15 mole %;
• (B) oxygen gas in the range of from about 1 mole % to about 15 mole %;
• and (C) an organic reductant selected from the group consisting of an alkane, an alkene, an alcohol, an ether, an ester, a carboxylic acid, an aldehyde, a ketone, a carbonate and combinations thereof;
• and
• an oxide of sulfur;
• wherein said organic reductant and said NOx are present in a carbon:NOx molar ratio from about 0.5:1 to about 24:1.

A method for reducing NOx comprising the steps of:

• providing a gas mixture comprising NOx, an organic reductant and a compound comprising sulfur;
• and
• contacting said gas mixture with a catalyst, wherein said catalyst comprises a metal oxide catalyst support, a catalytic metal oxide comprising gallium oxide or silver oxide;
• and at least one promoting metal selected from the group consisting of silver, cobalt, molybdenum, tungsten, indium, and bismuth.

A method for reducing NOx comprising:

• providing a gas mixture comprising (A) NOx;
• (B) water in the range of from about 1 mole % to about 15 mole %;
• (C) oxygen in the range of from about 1 mole % to about 15 mole %;
• (D) an organic reductant selected from the group consisting of an alkane, an alkene, an alcohol, an ether, an ester, a carboxylic acid, an aldehyde, a ketone, a carbonate and combinations thereof;
• and (E) an oxide of sulfur;
• and
• contacting said gas mixture with a catalyst comprising (i) a metal oxide catalyst support comprising at least one of alumina, titania, zirconia, silicon carbide, or ceria;
• (ii) a catalytic metal oxide present in an amount in a range of from about 1 mole % to about 31 mole % and comprising at least one of gallium oxide or silver oxide;
• and (iii) a promoting metal or combination of promoting metals present in an amount in a range of from about 1 mole % to about 31 mole % and selected from the group consisting of silver, cobalt, molybdenum, tungsten, indium, bismuth, indium and tungsten, silver and cobalt, indium and molybdenum, indium and silver, bismuth and silver, bismuth and indium, and molybdenum and silver;
• wherein said organic reductant and said NOx are present in a carbon:NOx molar ratio from about 0.5:1 to about 24:1;
• and wherein said contact is performed at a temperature in a range of from about 100° C. to about 600° C. and at a space velocity in a range of from about 5000 hr−1 to about 100000 hr−1.