The Boc Group, Inc.

Mark H Anderson

Shuen-Cheng Hwang

Robert Francis Workosky

Neeraj Saxena

James K Tseng

Ravi Kumar Jain

Robert James Ferrell

The present invention relates to a process for removing nitrogen oxides from gas streams such as furnace or utility boiler flue gas streams. An adsorber system is used to adsorb nitrogen oxides from the flue gas streams. An oxygen/ozone gas stream contacts the nitrogen oxides to convert the nitrogen oxides to N O which will exit the adsorber with the oxygen stream.

Removal of nitrogen oxides from gas streams

Nitric oxide is removed from a gas stream by contacting the gas stream with oxygen in the presence of a metal-cation exchanged zeolite, thereby oxidizing the nitric oxide to nitrogen dioxide, then contacting the resulting nitrogen dioxide-containing gas stream with ozone, thereby converting the nitrogen dioxide to nitric acid, nitric acid precursors or mixtures thereof, then contacting the gas stream with an aqueous liquid, thereby scrubbing the nitric acid, nitric acid precursors or mixtures thereof from the gas stream. Contact of the gas stream with oxygen in the presence of a zeolite is carried out at a temperature above the temperature at which significant adsorption of nitrogen dioxide occurs, and the aqueous liquid used as scrubbing agent preferably has a pH greater than 7.

Removal of nitric oxide from gas streams

Nitrogen oxides are removed from a waste gas stream by contacting the waste gas stream with ammonia, thereby reducing the nitrogen oxides to nitrogen. Residual nitrogen oxides and unreacted ammonia in the waste gas stream leaving the nitrogen oxides reducing step are oxidized to nitrogen pentoxide or nitric acid by contacting this gas stream with ozone. Contact of the ozone and waste gas is preferably carried out in the presence of an aqueous solution at a pH above about 9 and at a temperature above about 75&deg; C., and this step is preferably carried out in the presence of an ammonia-oxidizing catalyst.

Reduction of toxic substances in waste gas emissions

The present invention relates to a process for removing nitrogen oxides from gas streams such as furnace or utility boiler flue gas streams. An ozone adsorption system is used to adsorb and concentrate ozone. A slip stream containing nitrogen oxides is introduced into an ozone adsorption system to desorb ozone and the ozone-containing slip stream gas is then directed to a reactor duct along with the primary nitrogen oxide-containing gas stream where the nitrogen oxides are converted to N.sub.2 O.sub.5.

Process for the removal of nitrogen oxides from gas streams

A process for the removal of a high percentage of NOx and SOx from the gaseous effluent of a metal pickling operation comprising passing the effluent through an aqueous scrubber, treating the gaseous effluent from the scrubber with ozone, passing the effluent from the ozone treatment through a second aqueous scrubber thereby removing at least 80 vol % of the NOx and SOx present in the original effluent. The scrubbing solutions in both of the scrubbers preferably have a pH of from 7 to 14, more preferably 10 to 14. The scrubbing solutions in both scrubbers are caustic solutions containing sodium hydroxide or calcium hydroxide. The NOx and SOx in the scrubbers are converted into nitrate salts and sulfate salts, which are removed from the scrubbers.

Growing community of inventors

Bethlehem, PA, United States of America

Mark H Anderson