A method for the production of nitric acid, comprising a step of oxidation of ammonia in the presence of a catalyst, comprising a step of monitoring the temperature of said catalyst by at least one contactless infrared sensor.

An apparatus is provided for treatment of process gas formed during nitric acid production by catalytic oxidation of NH.sub.3. The apparatus includes a reactor, a first catalyst bed for N.sub.2O decomposition, an absorption tower to react the NO.sub.x formed with an absorption medium downstream of the first catalyst bed, a device for adding NH.sub.3 added to tailgas entering the second catalyst bed, and a second catalyst bed for NO.sub.x reduction and further decrease in N.sub.2O in the tailgas exiting the absorption tower. The second catalyst bed contains at least one iron-loaded zeolite catalyst. N.sub.2O removal in the first catalyst bed is limited such that the process gas exiting the first catalyst bed exhibits a N.sub.2O content of >100 ppmv and a molar N.sub.2O/NO.sub.x ratio of >0.25. Treated gas exiting the second catalyst bed has a NO.sub.x concentration of <40 ppmv and a N.sub.2O concentration of <200 ppmv.

An ammonia oxidation catalyst basket design has two support grids. A first grid supports the primary catalyst and a separate, second grid supports the secondary catalyst. This dual grid design separates the two catalysts, and enables the catalysts to be independent of each other. Any interruption in the primary or the secondary catalyst does not impede or adversely impact on the structure or function of the other catalyst.

An ammonia oxidation catalyst basket design has two support grids. A first grid supports the primary catalyst and a separate, second grid supports the secondary catalyst. This dual grid design separates the two catalysts, and enables the catalysts to be independent of each other. Any interruption in the primary or the secondary catalyst does not impede or adversely impact on the structure or function of the other catalyst.

A nitric acid production process, comprising tertiary abatement of N2O and NOx on a tail gas withdrawn from an absorption stage, said abatement including passing the tail gas over a sequence of a deN2O stage comprising a Fe-z catalyst and a deNOx stage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.

An ammonia oxidation catalyst basket design has two support grids. A first grid supports the primary catalyst and a separate, second grid supports the secondary catalyst. This dual grid design separates the two catalysts, and enables the catalysts to be independent of each other. Any interruption in the primary or the secondary catalyst does not impede or adversely impact on the structure or function of the other catalyst.

An ammonia oxidation catalyst basket design has two support grids. A first grid supports the primary catalyst and a separate, second grid supports the secondary catalyst. This dual grid design separates the two catalysts, and enables the catalysts to be independent of each other. Any interruption in the primary or the secondary catalyst does not impede or adversely impact on the structure or function of the other catalyst.

A process is disclosed for removing nitrous components from a raw liquid nitric acid stream to produce a bleached nitric acid product (55). The raw liquid nitric acid stream (37) is from an absorber (19) of a nitric acid process. The process comprises contacting the raw nitric acid liquid stream with an oxidising gas (12) in a bleaching stage (52). At least some of the gas effluent (12c) from the bleaching stage enters (12d) a combustion stage (15) of the nitric acid process. The oxidising gas (12) entering the bleaching stage (52) may comprise at least about one-third of an oxidising gas feed (12) to the nitric acid process. At least about one-tenth of the bleaching stage gas effluent (12c) may enter (12d) the combustion stage (15).

A process comprising: subjecting a process gas containing NOx to a stage for absorption of NOx in a suitable absorption means, obtaining nitric acid and a tail gas containing nitrogen, argon and residual NOx; subjecting said tail gas to a treatment which comprises at least one NOx removal stage, obtaining a conditioned tail gas; subjecting at least a portion of said conditioned tail gas to a separation treatment, obtaining a product stream containing argon and a product stream containing nitrogen.