Device and method for decomposing nitrogen oxides

A process for decomposing nitrogen (II) oxide or a mixture containing nitrogen (II) oxide and/or a nitrogen oxide of nitrogen oxidation state greater than 2 contained in an effluent composition which process comprises the steps of:

• (a) passing the effluent composition through a first reaction chamber where the effluent composition is contacted with oxygen in the presence of an oxidation catalyst at a temperature range of from 200 to 800° C. and at least a proportion of the nitrogen (II) oxide is oxidized to a nitrogen oxide having a nitrogen oxidation state of greater than 2;
• and
• (b) thereafter passing said effluent composition through a second reaction chamber where said oxidized effluent composition is contacted with an oxidisable material at a temperature in the range of from 100 to 1000° C., and reduces at least a portion of the nitrogen oxides having a nitrogen oxidation state of greater than 2 to produce molecular nitrogen and a reduceable oxide of said oxidation material;
• and
• wherein an electromotive force is applied to the oxidisable material substantially only when the effluent composition is present in the second reaction chamber.

A process for decomposing nitrogen (II) oxide or a mixture containing nitrogen (II) oxide and/or a nitrogen oxide of nitrogen oxidation state greater than 2 contained in an effluent composition which process comprises the steps of:

• (a) passing the effluent composition through a first reaction chamber where the effluent composition is contacted with oxygen in the presence of an oxidation catalyst at a temperature range of from 200 to 800° C. and at least a proportion of the nitrogen (II) oxide is oxidized to a nitrogen oxide having a nitrogen oxidation state of greater than 2;
• and
• (b) thereafter passing said effluent composition through a second reaction chamber where said oxidized effluent composition is contacted with an oxidisable material at a temperature in the range of from 100 to 1000° C., and reduces at least a portion of the nitrogen oxides having a nitrogen oxidation state of greater than 2 to produce molecular nitrogen and a reduceable oxide of said oxidation material;
• wherein an electromotive force is applied across the oxidisable material in the second reaction chamber;
• and
• wherein electromotive force applied to the oxidisable material is a direct current which regenerates the oxidisable material.

A device for decomposing a nitrogen (II) oxide or a mixture of nitrogen (II) oxide and a nitrogen oxide of nitrogen oxidation state greater than 2 in a gaseous effluent composition wherein said device comprises;

• a first reaction chamber containing an oxidation catalyst which, in use, oxidizes said nitrogen (II) oxide to nitrogen (IV) oxide and/or an oxide of nitrogen having a nitrogen oxidation state of more than 2 and a second reaction chamber formed and arranged in series with said first reaction chamber, wherein the second reaction chamber contains an oxidisable material which, in use, reduces said nitrogen (IV) oxide and/or the nitrogen oxides having a nitrogen oxidation state of more than 2 from said first reaction chamber to produce molecular nitrogen and said oxidisable material is oxidized to a reduceable oxide thereof;
• wherein said oxidation catalyst comprises an inorganic oxide support which is impregnated with one or more metals and/or metal compounds;
• and
• wherein said support comprises from 85 to 98 wt % of the metal or metal compound and from 2 to 15 wt % of the total weight of the oxidation catalyst.