A catalyst includes a gas-permeable textile sheet material made of noble-metal-containing wire having a three-dimensional secondary structure produced thereon. The secondary structure is a three-dimensional dent structure including dents arranged adjacent to each other in rows in two spatial directions. The dents are in the form of a hexagon. The dent structure is formed by self-organization in a denting process.

A nitric acid production process, comprising tertiary abatement of N2O and NOx on a tail gas withdrawn from an absorption stage, said abatement including passing the tail gas over a sequence of a deN2O stage comprising a Fe-z catalyst and a deNOx stage comprising a V2O5-TiO2 catalyst in the presence of gaseous ammonia, wherein the tail gas at the inlet of deN2O stage and the tail gas at the inlet of deNOx stage have a temperature greater than 400° C.

A nitric acid production process, comprising tertiary abatement of N2O and NOx on a tail gas withdrawn from an absorption stage, said abatement including passing the tail gas over a sequence of a deN2O stage comprising a Fe-z catalyst and a deNOx stage comprising a V2O5-TiO2 catalyst in the presence of gaseous ammonia, wherein the tail gas at the inlet of deN2O stage and the tail gas at the inlet of deNOx stage have a temperature greater than 400° C.

A dual pressure plant for the production of nitric acid, comprising: an air compressor; a converter, operating at a low pressure (LP), operable to be fed with a stream of an ammonia/pressurized air mixture to produce an LP gaseous NOx gas/steam mixture, comprising water, NO, NO.sub.2 and N.sub.2O.sub.4; a NOx gas compressor; an absorber unit (6); and a bleacher unit;
wherein the plant comprises means for directing the NOx-loaded stripping gas to the downstream side of the NOx gas compressor;
the plant being characterized in that it further comprises a high-pressure (HP) water electrolyser, in fluid communication with the bleacher unit.

A catalyst gauze for an ammonia oxidation process is described, containing a first layer of knitted first wire material, whereby said first wire material is made from a platinum-rhodium alloy, characterized in that said first layer contains an activator in the form of a second wire material which is knitted among the first wire material and which is made from un-alloyed platinum.

The disclosure pertains to a nitric acid production process and plant. The process involves supplying an oxygen gas stream and ammonia feedstock to the burner section. In embodiments, a part of the tail gas stream (4) is heated in a tail gas heating section (7) and supplied to the burner section (1).

Three-dimensionally knitted noble metal gauzes, or sections of such gauzes, for carrying out catalytic reactions of fluids are knitted in two or multiple layers and the meshes of the individual layers are connected to one another in one form by a pile thread or multiple pile threads, so that the noble metal gauze has a tertiary structure.

The disclosure pertains to a nitric acid production process and plant. The process involves supplying an oxygen gas stream and ammonia feedstock to the burner section. In embodiments, a part of the tail gas stream (4) is heated in a tail gas heating section (7) and supplied to the burner section (1).

A system suitable for oxidizing ammonia with oxygen in the presence of catalysts is described. The system includes a reactor equipped with at least one supply line for a reactant gas mixture and at least one discharge line for a process gas; a catalyst comprising at least one transition metal oxide that is not an oxide of a platinum metal; and a device for adjusting a molar ratio of oxygen to ammonia of less than or equal to 1.75 mol/mol in the reactant gas mixture by mixing an oxygen-containing gas stream having an O.sub.2 content of <20% by volume with a chosen amount of ammonia. The oxygen-containing gas stream is produced by a device for: diluting an air stream with a gas stream comprising less than 20% by volume oxygen; or depleting oxygen from an oxygen-containing gas mixture, preferably from air; or by a combination thereof.

A dual-pressure plant for the synthesis of nitric acid comprising: a reactor (4) providing a gaseous effluent (15) containing nitrogen oxides; an absorption tower (6) nitrogen oxides react with water providing raw nitric acid and, said absorption tower operating at a pressure greater than the pressure of the reactor; a compressor (5) elevating the pressure of the reactor effluent (15) to the absorption pressure; said plant also comprising a first bleacher (37) and a second bleacher (7), said first bleacher (37) stripping with air (39) nitrogen oxides from the output stream (27) of the absorption tower (6) providing a partially stripped nitric acid stream (40) and a nitrogen oxides-loaded air stream (41), the former being fed to the second bleacher (7) and the latter being recycled to the delivery-side of said compressor (5).