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.

Known catalyst systems for the catalytic combustion of ammonia to form nitrogen oxides consist of a plurality of single- or multilayer catalyst gauzes warp-knitted, weft-knitted or woven from platinum-based noble metal wire, which, when arranged one behind the other in a fresh gas flow direction, form a front group of gauze layers and at least one downstream group of gauze layers arranged after the front group. To provide from this starting point a catalyst system for use in a medium-pressure plant for ammonia oxidation, with which a high service life and a high yield of the main product NO can be achieved, it is proposed that the front group comprises a gauze layer or a plurality of gauze layers made of a first, rhodium-rich noble metal wire, wherein the gauze layer or one of the gauze layers made of the rhodium-rich noble metal wire is a front gauze layer facing the fresh gas, and that the downstream group comprises gauze layers made of a second, rhodium-poor noble metal wire, wherein the rhodium content in the rhodium-rich noble metal wire is at least 7 wt. % and no more than 9 wt. % and is at least 1 percentage point higher than the rhodium content in the rhodium-poor noble metal wire

Known catalyst systems for the catalytic combustion of ammonia to form nitrogen oxides consist of a plurality of catalyst gauze layers which are knitted, woven or braided from platinum-based precious metal wire, which form a catalyst package when arranged after one another when viewed in a fresh gas flow direction. In order to provide a catalyst system on this basis for use in a medium-pressure system, with which a yield of the main product NO comparable to the industry standard can be achieved despite the reduced precious metal use, according to the invention, the catalyst package is formed from a front assembly with three catalyst gauzes with a first average mass per unit area and a downstream assembly of catalyst gauze layers arranged after the front assembly and having a second average mass per unit area, wherein the average mass per unit area of the front assembly has a short weight in the region of 1.5% to 29% in relation to the second average mass per unit area, and the first average mass per unit area lies in the regions of 410 to 30 g/m.sup.2 and the second average mass per unit area lies in the region of 540 to 790 g/m.sup.2.

The invention relates to a precious metal mesh which is knitted on a flat-bed knitting machine, having at least two float stitches per wale, thus having a significantly higher density for a given latch needle density of the flat-bed knitting machine than the precious metal mesh according to the prior art.

Process for reducing the content of NOx and N2O from an input tail gas (10) of a nitric acid process, said input tail gas having a temperature lower than 400 C., the process comprising an abatement stage at least including a deN2O stage and deNOx stage and providing a conditioned tail gas (12) having a temperature greater than the input tail gas (10), wherein, prior to submission to said abatement stage, said input tail gas (10) is pre-heated to a temperature of at least 400 C. by indirect heat exchange with at least a portion of said conditioned gas (12).

The invention relates to a method for producing noble metal nets on flatbed knitting machines, the steps involvingproviding noble metal wire comprising platinumproviding yarn that is combustible or soluble in solventknitting two-bed items by simultaneous knitting on the front and rear needle beds and joining the two knitted fabrics by means of connecting pile threads, wherein, on the front or on the rear needle bed, a combustible or soluble yarn is used which is burnt off or dissolved after the knitting process, and a noble metal wire is used on the other needle bed and for the pile threads such that, after the combustible or soluble yarn has been burnt off or dissolved, there remain only the pile threads and the knitted fabric made of noble metal wire and produced on the rear or front needle bed.

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.

The present disclosure provides systems and method for electric plasma synthesis of nitric oxide. In particular, the present disclosure provides a nitric oxide (NO) generation system configured to produce a controllable output of therapeutic NO gas at the point of care.

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.