Abstract: 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 O2 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.

Abstract: An apparatus is provided for treatment of process gas formed during nitric acid production by catalytic oxidation of NH3. The apparatus includes a reactor, a first catalyst bed for N2O decomposition, an absorption tower to react the NOx formed with an absorption medium downstream of the first catalyst bed, a device for adding NH3 added to tailgas entering the second catalyst bed, and a second catalyst bed for NOx reduction and further decrease in N2O in the tailgas exiting the absorption tower. The second catalyst bed contains at least one iron-loaded zeolite catalyst. N2O removal in the first catalyst bed is limited such that the process gas exiting the first catalyst bed exhibits a N2O content of >100 ppmv and a molar N2O/NOx ratio of >0.25. Treated gas exiting the second catalyst bed has a NOx concentration of <40 ppmv and a N2O concentration of <200 ppmv.

Abstract: A method for disposing a bed comprising particles in a burner through which a gas can flow, more particularly in a burner basket of an ammonia oxidation burner, where the particles are disposed such that the bed has a greater flow resistance in an edge region of the burner than in an inner region of the burner. Further, a burner basket for a burner may have a bed comprising particles, wherein the particles are disposed such that the bed has a greater flow resistance in an edge region of the burner basket than in an inner region of the burner basket.

Abstract: 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 O2 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.

Abstract: 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 O2 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.

Abstract: An apparatus is provided for carrying out a process for removing N2O and NOx from offgases by catalytic decomposition of N2O by means of iron-containing zeolite catalysts and catalytic reduction of the NOx by means of reducing agents, the deNOx stage connected downstream of the deN2O stage being operated at inlet temperatures of T<=400° C., and the inlet gas for the deN2O stage comprising water and having a selected N2O/NOx ratio, and the operating parameters of temperature, pressure and space velocity of the deN2O stage being selected so as to result in an N2O degradation of 80 to 98%. Under these conditions, a degree of NOx oxidation of 30-70% is established at the outlet of the deN2O stage, which is defined as the ratio of the molar amounts of NO2 to the total molar amount of NOx. The result of this is that the downstream deNOx stage can be operated under optimal conditions.

Abstract: A process for removing N2O and NOx from offgases by catalytic decomposition of N2O by means of iron-containing zeolite catalysts and catalytic reduction of the NOx by means of reducing agents, the deNOx stage connected downstream of the deN2O stage being operated at inlet temperatures of T<=400° C., and the inlet gas for the deN2O stage comprising water and having a selected N2O/NOx ratio, and the operating parameters of temperature, pressure and space velocity of the deN2O stage being selected so as to result in an N2O degradation of 80 to 98%. Under these conditions, a degree of NOx oxidation of 30-70% is established at the outlet of the deN2O stage, which is defined as the ratio of the molar amounts of NO2 to the total molar amount of NOx. The result of this is that the downstream deNOx stage can be operated under optimal conditions. Also provided is an apparatus for carrying out the process.

Abstract: A method for disposing a bed comprising particles in a burner through which a gas can flow, more particularly in a burner basket of an ammonia oxidation burner, where the particles are disposed such that the bed has a greater flow resistance in an edge region of the burner than in an inner region of the burner. Further, a burner basket for a burner may have a bed comprising particles, wherein the particles are disposed such that the bed has a greater flow resistance in an edge region of the burner basket than in an inner region of the burner basket.

Abstract: The invention relates to a process and apparatus for preparing nitric acid by catalytic oxidation of NH3 by means of oxygen and subsequent reaction of the NOx formed with an absorption medium in an absorption tower, which comprises a catalyst bed for N2O decomposition arranged in the process gas downstream of the catalytic NH3 oxidation and upstream of the absorption tower in the flow direction and a catalyst bed for NOx reduction and effecting a further decrease in the amount of N2O arranged in the tailgas downstream of the absorption tower in the flow direction, wherein the amount of N2O removed in the catalyst bed for N2O removal arranged in the process gas is not more than that which results in an N2O content of >100 ppmv and a molar N2O/NOx ratio of >0.

Abstract: The invention relates to a process and apparatus for preparing nitric acid by catalytic oxidation of NH3 by means of oxygen and subsequent reaction of the NOx formed with an absorption medium in an absorption tower, which comprises a catalyst bed for N2O decomposition arranged in the process gas downstream of the catalytic NH3 oxidation and upstream of the absorption tower in the flow direction and a catalyst bed for NOx reduction and effecting a further decrease in the amount of N2O arranged in the tailgas downstream of the absorption tower in the flow direction, wherein the amount of N2O removed in the catalyst bed for N2O removal arranged in the process gas is not more than that which results in an N2O content of >100 ppmv and a molar N2O/NOx ratio of >0.

Abstract: Improved reactors for catalytic, exothermic gas phase reactions with, as seen in the flow direction of a feed gas, which contains at least one oxidant and at least one component to be oxidized, an entry zone (1), a reaction zone (2) comprising at least one catalyst (4) and an exit zone (3) for the product gas are described. The reactors, at least in the area of the entry zone (1), have means, for example insulating jackets (6) and/or devices for the transport of cooling agents, which decrease the transport of heat produced in the reaction zone (2) into the entry zone (1) and thus decrease the risks of pre-ignition of the feed gas mixture employed or of the course of undesired side reactions in the entry zone (1) and/or wherein the inner walls of the reactor, at least in the area of the entry zone (1), are elaborated from inert material. The feed gas enters into the entry zone (1) as a homogeneous gas mixture with respect to its substance composition via one or more feed lines (30).

Abstract: 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 O2 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.

Abstract: Disclosed herein is a device and method for lowering the content of NOX and N2O in gases. The device comprises a container having therein two reaction steps connected in series. The first step removes NOX (DeNOX stage) by reducing NOX with a nitrogen-containing reducing agent. Downstream thereof, the second step removes N2O by catalytic decomposition of N2O to N2 and O2 (DeN2O stage). Each step comprises one or more catalyst beds through which flows gas to be purified. The catalyst bed of the DeNOX stage containing zeolites doped with transition metals, including lanthanides. The at least one catalyst bed of the DeN2O-stage contains one or more catalytically active compounds of elements selected from groups 5 to 11 of the Periodic Table, but not iron-doped zeolites. A device for introducing a nitrogen-containing reducing agent into the stream of the NOX and N2O-containing gas is further disposed upstream of the DeNOX stage.

Abstract: Improved reactors for catalytic, exothermic gas-phase reactions having, viewed in the flow direction of a feed gas, an inlet zone (1), a reaction zone (2) containing at least one catalyst (4), and an outlet zone (3) for the product gas, are described. The reactors are provided in the inlet zone (1) or in the inlet zone (1) and the reaction zone (2) with an insulating liner (6) and/or apparatuses for the transport of cooling media and/or the interior walls of the reactor in the inlet zone (1) or in the inlet zone (1) and the reaction zone (2) consist of inert material. The insulating liner and/or cooling media reduce heat transport from the reaction zone (2) into the inlet zone (1) and thus reduce the risk of preignition of the feed gas mixture used or occurrence of undesirable secondary reactions in the inlet zone (1).

Abstract: A device and a method are described for lowering the content of NOx and N2O in gases.

Abstract: Catalysts for the decomposition of N2O into nitrogen and oxygen in the gas phase, which comprises a porous support composed of polycrystalline or vitreous inorganic material, a cerium oxide functional layer applied thereto and a layer of oxidic cobalt-containing material applied thereto are described. The catalysts can be used, in particular, as secondary or tertiary catalysts in nitric acid plants.

Abstract: The invention relates to a process and apparatus for preparing nitric acid by catalytic oxidation of NH3 by means of oxygen and subsequent reaction of the NOx formed with an absorption medium in an absorption tower, which comprises a catalyst bed for N2O decomposition arranged in the process gas downstream of the catalytic NH3 oxidation and upstream of the absorption tower in the flow direction and a catalyst bed for NOx reduction and effecting a further decrease in the amount of N2O arranged in the tailgas downstream of the absorption tower in the flow direction, wherein the amount of N2O removed in the catalyst bed for N2O removal arranged in the process gas is not more than that which results in an N2O content of >100 ppmv and a molar N2O/NOx ratio of >0.

Abstract: A process for removing N2O and NOx from offgases by catalytic decomposition of N2O by means of iron-containing zeolite catalysts and catalytic reduction of the NOx by means of reducing agents, the deNOx stage connected downstream of the deN2O stage being operated at inlet temperatures of T<=400° C., and the inlet gas for the deN2O stage comprising water and having a selected N2O/NOx ratio, and the operating parameters of temperature, pressure and space velocity of the deN2O stage being selected so as to result in an N2O degradation of 80 to 98%. Under these conditions, a degree of NOx oxidation of 30-70% is established at the outlet of the deN2O stage, which is defined as the ratio of the molar amounts of NO2 to the total molar amount of NOx. The result of this is that the downstream deNOx stage can be operated under optimal conditions. Also provided is an apparatus for carrying out the process.

Abstract: Improved reactors for catalytic, exothermic gas phase reactions with, as seen in the flow direction of a feed gas, which contains at least one oxidant and at least one component to be oxidized, an entry zone (1), a reaction zone (2) comprising at least one catalyst (4) and an exit zone (3) for the product gas are described. The reactors, at least in the area of the entry zone (1), have means, for example insulating jackets (6) and/or devices for the transport of cooling agents, which decrease the transport of heat produced in the reaction zone (2) into the entry zone (1) and thus decrease the risks of pre-ignition of the feed gas mixture employed or of the course of undesired side reactions in the entry zone (1) and/or wherein the inner walls of the reactor, at least in the area of the entry zone (1), are elaborated from inert material. The feed gas enters into the entry zone (1) as a homogeneous gas mixture with respect to its substance composition via one or more feed lines (30).

Abstract: Catalysts for the decomposition of N2O into nitrogen and oxygen in the gas phase, which comprises a porous support composed of polycrystalline or vitreous inorganic material, a cerium oxide functional layer applied thereto and a layer of oxidic cobalt-containing material applied thereto are described. The catalysts can be used, in particular, as secondary or tertiary catalysts in nitric acid plants.