A process for catalytic oxidation of ammonia gas by way of an oxygen-containing gas in a presence of a noble metal-containing catalyst may be employed to give nitrogen monoxide. A temperature of an ammonia/air mixed gas may be optimized in respect of nitrogen monoxide selectivity of the reaction before contact with the catalyst. Examination of catalytic NH.sub.3 oxidation according to 4NH.sub.3+5O.sub.2.fwdarw.4NO+6H.sub.2O revealed that an optimum mode of operation of an NH.sub.3 burner in an HNO.sub.3 plant is not to be achieved by maintenance of a constant gauze temperature of the catalyst gauze by automatic setting of the NH.sub.3:air ratio. Rather, there is an optimum temperature for each process condition that should be set not by changing the NH.sub.3:air ratio but instead by altering the temperature of the NH.sub.3/air mixed gas before contact with the catalyst gauzes.

A process for catalytic oxidation of ammonia gas by way of an oxygen-containing gas in a presence of a noble metal-containing catalyst may be employed to give nitrogen monoxide. A temperature of an ammonia/air mixed gas may be optimized in respect of nitrogen monoxide selectivity of the reaction before contact with the catalyst. Examination of catalytic NH.sub.3 oxidation according to 4NH.sub.3+5O.sub.2.fwdarw.4NO+6H.sub.2O revealed that an optimum mode of operation of an NH.sub.3 burner in an HNO.sub.3 plant is not to be achieved by maintenance of a constant gauze temperature of the catalyst gauze by automatic setting of the NH.sub.3:air ratio. Rather, there is an optimum temperature for each process condition that should be set not by changing the NH.sub.3:air ratio but instead by altering the temperature of the NH.sub.3/air mixed gas before contact with the catalyst gauzes.

In examples, there is a device for converting ammonia (NH.sub.3) in a human breath sample to nitric oxide (NO). The device comprises a tube and a heater. The tube comprises an inlet, an outlet, and a wall defining an internal surface of the tube and an external surface of the tube. The wall comprises substantially the same material along a thickness from the internal surface of the tube to the external surface of the tube. The material is catalytic for conversion of ammonia to nitric oxide. The heater is configured to heat the wall.

An apparatus and a process are described for preparation of nitric acid from ammonia and oxygenous gas by the single pressure or dual pressure process, in which the oxidation of the ammonia used is accomplished by means of compressed process air which has been compressed in at least one compressor over a catalyst, and the nitrous gas formed by the oxidation is at least partly absorbed by water, forming nitric acid, and the unabsorbed residual gas is expanded for the purpose of recovering compressor work in at least one multistage residual gas turbine (1). The characteristic features of the process and the apparatus are that, at least during the startup and/or shutdown of the nitric acid plant, in the multistage residual gas turbine (1), a substream (3) of the medium (4) flowing through the multistage residual gas turbine (1) is withdrawn and that a substream (2) of the medium (4a) supplied to the multistage residual gas turbine (1) is optionally withdrawn upstream of the multistage residual gas turbine (1), and that the medium withdrawn is supplied to a chimney (5), the withdrawal of the substream (3) taking place between two or more residual gas turbine stages. This measure can effectively prevent freezing of the residual gas turbine.

An apparatus and a process are described for preparation of nitric acid from ammonia and oxygenous gas by the single pressure or dual pressure process, in which the oxidation of the ammonia used is accomplished by means of compressed process air which has been compressed in at least one compressor over a catalyst, and the nitrous gas formed by the oxidation is at least partly absorbed by water, forming nitric acid, and the unabsorbed residual gas is expanded for the purpose of recovering compressor work in at least one multistage residual gas turbine (1). The characteristic features of the process and the apparatus are that, at least during the startup and/or shutdown of the nitric acid plant, in the multistage residual gas turbine (1), a substream (3) of the medium (4) flowing through the multistage residual gas turbine (1) is withdrawn and that a substream (2) of the medium (4a) supplied to the multistage residual gas turbine (1) is optionally withdrawn upstream of the multistage residual gas turbine (1), and that the medium withdrawn is supplied to a chimney (5), the withdrawal of the substream (3) taking place between two or more residual gas turbine stages. This measure can effectively prevent freezing of the residual gas turbine.

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.

The invention relates to a process and apparatus for preparing nitric acid by catalytic oxidation of NH.sub.3 by means of oxygen and subsequent reaction of the NO.sub.x formed with an absorption medium in an absorption tower, which comprises a catalyst bed for N.sub.2O decomposition arranged in the process gas downstream of the catalytic NH.sub.3 oxidation and upstream of the absorption tower in the flow direction and a catalyst bed for NO.sub.x reduction and effecting a further decrease in the amount of N.sub.2O arranged in the tailgas downstream of the absorption tower in the flow direction, wherein the amount of N.sub.2O removed in the catalyst bed for N.sub.2O removal arranged in the process gas is not more than that which results in an N.sub.2O content of >100 ppmv and a molar N.sub.2O/NO.sub.x ratio of >0.25 before entry of the tailgas into the catalyst bed for NO.sub.x reduction and the catalyst bed for NO.sub.x reduction and effecting a further decrease in the amount of N.sub.2O arranged in the tailgas contains at least one iron-loaded zeolite catalyst and NH.sub.3 is added to the tailgas before entry into the catalyst bed in such an amount that an NO.sub.x concentration of <40 ppmv results at the outlet from the catalyst bed and the operating parameters are selected in such a way that an N.sub.2O concentration of <200 ppmv results.

The present invention provides a catalyst for production of nitric oxide from ammonia and oxygen. The catalyst has the composition A.sub.3-xB.sub.xO.sub.9-y, wherein A and B are selected from the group Mn, Co, Cr, Fe and Al, x is between 0 and 3 and y is between 0 and 6. The catalyst has a high selectivity towards nitric oxide and a low ignition temperature in the reactor. Further the present invention relates to a method for the production of gas comprising nitric oxide by the catalyst of the present invention. The produced gas has a low content of nitrous oxide.

A device D accommodated in a reactor R and containing a gas- and/or liquid-permeable bottom B, in the peripheral region of which is arranged a lateral boundary W which completely surrounds the bottom B and forms a volume V which is partially or completely filled with catalytic and/or non-catalytic moldings, there optionally being located on the side facing the bottom B in the upstream direction at least one noble metal and/or non-noble metal fabric, wherein a thermal insulation layer S is located on at least part of the surface of the inner side of the lateral boundary W of the device D, the material for the thermal insulation layer S being selected from the group consisting of ceramic material, microporous material and silicate fibers.

A burner basket for an ammonia oxidation burner includes a gas-permeable bottom plate, with a side wall that is spaced apart from the bottom plate by a gap, and a retaining device covering the bottom plate and the gap for retaining particles of a bulk material that can be arranged in the burner basket. A fastening element is arranged on the bottom plate, by which the retaining device is fixed in place. An ammonia oxidation burner comprises a burner for oxidizing ammonia and a burner basket.