Abstract: A method and device for removal of N2O in nitric acid production are disclosed. The device is arranged after a heat exchanger, post ammonia burning, before the absorption tower and contains a catalyst, which essentially comprises one or several iron loaded zeolites.

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: Improved reactors for catalytic, exothermic gas-phase reactions, which comprise, viewed in the flow direction of a feed gas, an inlet zone (1), a reaction zone (2) containing at least one catalyst (4) an outlet zone (3) for the product gas, are described. The reactors are provided in the region of the inlet zone (1) or in the region of the inlet zone (1) and the reaction zone (2) with means, for example an insulating liner (6) and/or apparatuses for the transport of cooling media, which 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) and/or the interior walls of the reactor in the region of the inlet zone (1) or in the region of the inlet zone (1) and the reaction zone (2) consist of inert material.

Abstract: The method comprises passing an N2O- and NOx-containing gas over a sequence of two catalyst beds, adding reducing agents for NOx and for N2O between the catalyst beds in such an amount that not only NOx but also a predetermined proportion of N2O is reduced. The reaction conditions are set so that the N2O content of the gas is reduced by not more than 95%, based on the N2O content at the entrance of the first catalyst bed, by decomposition to nitrogen and oxygen in the first catalyst bed and that not only chemical reduction of NOx but also chemical reduction of N2O occurs in the second catalyst bed so that the N2O content of the gas is reduced by at least 50%, based on the N2O content at the entrance of the second catalyst bed.

Abstract: A process is described for reducing the NOx concentration and N2O concentration from the residual gas from nitric acid production. The process encompasses the passing of the residual gas leaving the absorption column, prior to entry into the residual gas turbine, through a combination of two stages. The first stage here reduces the NOx content and the second stage the N2O content of the gas, the NOx/N2O ratio prior to entry of the gas into the second stage being in the range from 0.001 to 0.5, and this gas being brought into contact in the second stage with a catalyst which is substantially composed of one or more iron-loaded zeolites.

Abstract: The disclosure involves a method for reducing the content of NOx and N2O in gases. The method includes the conduction of a gas containing N2O and NOX over a series of two catalyst beds containing of one or more zeolites charged with iron followed by the: addition of a reduction agent for NOX between the catalyst beds. The first catalyst bed reaction zone is used to degrade the N2O and the catalyst bed second reaction zone reduces the NOX and breaks down at least part of the remaining N2O. The inventive device comprises at least one radially traversed catalyst bed.

Abstract: The method comprises passing an N2O- and NOx-containing gas over a sequence of two catalyst beds, adding reducing agents for NOx and for N2O between the catalyst beds in such an amount that not only NOx but also a predetermined proportion of N2O is reduced. The reaction conditions are set so that the N2O content of the gas is reduced by not more than 95%, based on the N2O content at the entrance of the first catalyst bed, by decomposition to nitrogen and oxygen in the first catalyst bed and that not only chemical reduction of NOx but also chemical reduction of N2O occurs in the second catalyst bed so that the N2O content of the gas is reduced by at least 50%, based on the N2O content at the entrance of the second catalyst bed.

Abstract: A process for reducing the content of NOx and N2O in gases, in particular in process gases and offgases, which comprises the measures: a) addition of at least one nitrogen-containing reducing agent to the NOx- and N2O-containing gas in at least the amount required for complete reduction of the NOx; b) addition of a hydrocarbon, of carbon monoxide, of hydrogen, or of a mixture of one or more of these gases to the NOx- and N2O-containing gas for the reduction of the N2O; and c) introduction of the gas mixture into at least one reaction zone at temperatures of up to 450° C., which contains one or more iron-laden zeolites. The process can be used, in particular, in nitric acid production, for offgases from power stations or for gas turbines.

Abstract: A method of reducing the content of NOx and N2O in gases using a gaseous reducing agent which is used in the amount required for reduction of the NOx in the presence of one or more iron-laden zeolites which have no pores or channels having a width of greater than or equal to 7 ?ngström in the crystal structure and at temperatures of less than 450° C. in the reaction zone is described. In this method, the flow rate of the gas mixture and/or the amount of catalyst is/are selected so that the desired degree of decomposition of N2O is achieved. The method can be used, in particular, in nitric acid production, in power stations and in gas turbines.

Abstract: A method of reducing the N2O content in gases is described. A selected zeolite catalyst is used in the method. This catalyst is present in the H form and/or contains exchanged iron and is characterized by the presence of nonlattice aluminum in addition to the lattice aluminum in a molar ratio of from 1:2 to 20:1. The method can be used in nitric acid production for reducing the N2O content of process gases or offgases.

Abstract: The method comprises the following steps: conduction of the gas containing N2O and NOx over a series of two catalyst beds consisting of one or more zeolites° charged with iron: addition of a reduction agent for NOx between the catalyst beds; setting of a temperature of less than 500° C. in the first and second catalyst bed; setting of a gas pressure of at least 2 bar in the two catalyst beds; and the selection of a space velocity in the first and second catalyst bed that achieves a degradation of the N2O content of the gas in the first catalyst bed by a maximum of up to 90%, in relation to the N2O content at the entrance to the catalyst bed and an additional degradation of the N2O content of the gas in the second catalyst bed by at least 30% in relation to the N2O content at the entrance to the second catalyst bed. The first reaction zone is used to degrade the N2O and the second reaction zone reduces the NOx and breaks down at least part of the remaining N2O.

Abstract: A process for reducing the content of NOx and N2O in gases, in particular in process gases and offgases, which comprises the measures: a) addition of at least one nitrogen-containing reducing agent to the NOx- and N2O-containing gas in at least the amount required for complete reduction of the NOx, b) addition of a hydrocarbon, of carbon monoxide, of hydrogen or of a mixture of one or more of these gases to the NOx- and N2O-containing gas for the reduction of the N2O and c) introduction of the gas mixture into at least one reaction zone at temperatures of up to 450° C. which contains one or more iron-laden zeolites, is described. The process can be used, in particular, in nitric acid production, for offgases from power stations or for gas turbines.

Abstract: Catalyst for decomposing N2O, its use, and process for its production A process is described for the decomposition of N2O during nitric acid production by bringing the N2O-containg waste gas leaving the absorption column into contact with a catalyst which comprises at least one oxidic cobalt compound and at least one oxidic magnesium compound, under conditions which permit conversion of N2O to gaseous nitrogen and oxygen. The content of oxidic cobalt compounds is in the range from 0.1 to 50% by weight and the content of oxidic magnesium compounds is in the range from 50 to 99.9% by weight, based in each case on the total weight of the catalyst, and at least 30% of the Co atoms present in the catalyst are present in the trivalent state.

Abstract: Method of reducing the N2O content of gases and selected catalysts

Abstract: A method of reducing the content of NOx and N2O in gases using a gaseous reducing agent which is used in the amount required for reduction of the NOx in the presence of one or more iron-laden zeolites which have no pores or channels having a width of greater than or equal to 7 Ångström in the crystal structure and at temperatures of less than 450° C. in the reaction zone is described. In this method, the flow rate of the gas mixture and/or the amount of catalyst is/are selected so that the desired degree of decomposition of N2O is achieved.

Abstract: A method and device for removal of N2O in nitric acid production are disclosed. The device is arranged after a heat exchanger, post ammonia burning, before the absorption tower and contains a catalyst, which essentially comprises one or several iron-loaded zeolites.

Abstract: A process is described for reducing the NOx concentration and N2O concentration from the residual gas from nitric acid production. The process encompasses the passing of the residual gas leaving the absorption column, prior to entry into the residual gas turbine, through a combination of two stages. The first stage here reduces the NOx content and the second stage the N2O content of the gas, the NOx/N2O ratio prior to entry of the gas into the second stage being in the range from 0.001 to 0.5, and this gas being brought into contact in the second stage with a catalyst which is substantially composed of one or more iron-loaded zeolites.

Abstract: An apparatus and a process are described for reducing the content of NOx and N2O in process gases and waste gases. The apparatus encompasses at least one catalyst bed comprising a catalyst which is substantially composed of one or more iron-loaded zeolites, and two reaction zones, where the first zone (reaction zone I) serves for decomposing N2O and in the second zone (reaction zone II) NOx is reduced, and, located between the first and second zone, there is an apparatus for the introduction of NH3 gas.

Abstract: A process is described for the decomposition of N2O during nitric acid production by bringing the N2O-containg waste gas leaving the absorption column into contact with a catalyst which comprises at least one oxidic cobalt compound and at least one oxidic magnesium compound, under conditions which permit conversion of N2O to gaseous nitrogen and oxygen. The content of oxidic cobalt compounds is in the range from 0.1 to 50% by weight and the content of oxidic magnesium compounds is in the range from 50 to 99.9% by weight, based in each case on the total weight of the catalyst, and at least 30% of the Co atoms present in the catalyst are present in the trivalent state. The preparation of the catalyst involves dry mixing of the oxidic cobalt compounds and the oxidic magnesium compounds or of appropriate precursors which are converted into the oxidic compounds by heat treatment, and compacting the mix, with exclusion of water, so that the resultant catalyst has the desired envelope density.