Uhde Gmbh

Thyssenkrupp Industrial Solutions Ag

Thyssenkrupp Uhde Gmbh

Unde Gmbh

Meinhard Schwefer

Rolf Siefert

Michael Groves

Rainer Maurer

Jürgen Fuchs

Klaus Ruthardt

Alberto Cremona

Edoardo Vogna

Thomas Turek

Bernhard Hündgen

Jurgen Fuchs

Bernhard Hundgen

Markus Kögel

Carsten Gehlen

Joachim Motz

Christian Perbandt

Wolfgang Burckhardt

Frank Froehlich

Stefan Pinnow

Frank Seifert

Ivo Müller

Juergen Fuchs

Bernhard Huendgen

Bernhard HÜNDGEN

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 Ocontent of &#x3c;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.

Method for oxidizing ammonia and system suitable therefor

An apparatus is provided for treatment of process gas formed during nitric acid production by catalytic oxidation of NH. The apparatus includes a reactor, a first catalyst bed for NO decomposition, an absorption tower to react the NOformed with an absorption medium downstream of the first catalyst bed, a device for adding NHadded to tailgas entering the second catalyst bed, and a second catalyst bed for NOreduction and further decrease in NO in the tailgas exiting the absorption tower. The second catalyst bed contains at least one iron-loaded zeolite catalyst. NO removal in the first catalyst bed is limited such that the process gas exiting the first catalyst bed exhibits a NO content of &#x3e;100 ppmv and a molar NO/NOratio of &#x3e;0.25. Treated gas exiting the second catalyst bed has a NOconcentration of &#x3c;40 ppmv and a NO concentration of &#x3c;200 ppmv.

Method for removing NO and NOfrom the nitric acid production process, and an installation suitable for same

Methods for the combined elimination of both ammonia and lower alkanes and/or hydrogen, which are contained in one or more waste gas streams in an industrial plant, are disclosed herein. The method is effectuated by combined oxidation and reduction according to the reduction-oxidation process, wherein the ammonia and the lower alkanes and/or hydrogen are completely or partially reacted by chemical reaction to form nitrogen, carbon dioxide and water. The waste gas stream containing ammonia and lower alkanes and/or hydrogen is passed over one or more catalysts for the combined oxidation and reduction, and the oxygen content in the waste gas stream is set in such a way that ammonia and the lower alkanes and/or hydrogen are oxidized first in an oxidation zone to form nitrogen, carbon dioxide and water, and the nitrogen oxides resulting therefrom are subsequently reduced in a reduction zone to form elemental nitrogen.

Elimination of ammonia and lower alkanes and/or hydrogen from waste gas streams in industrial plants

A process for removing NO and NOfrom offgases by catalytic decomposition of NO by means of iron-containing zeolite catalysts and catalytic reduction of the NOby means of reducing agents, the deNOstage connected downstream of the deNO stage being operated at inlet temperatures of T&#x3c;=400&#xb0; C., and the inlet gas for the deNO stage comprising water and having a selected NO/NOratio, and the operating parameters of temperature, pressure and space velocity of the deNO stage being selected so as to result in an NO degradation of 80 to 98%. Under these conditions, a degree of NOoxidation of 30-70% is established at the outlet of the deNO stage, which is defined as the ratio of the molar amounts of NOto the total molar amount of NO. The result of this is that the downstream deNOstage can be operated under optimal conditions. Also provided is an apparatus for carrying out the process.

Process and apparatus for eliminating NOX and N2O

The invention relates to a process and apparatus for preparing nitric acid by catalytic oxidation of NHby means of oxygen and subsequent reaction of the NOformed with an absorption medium in an absorption tower, which comprises a catalyst bed for NO decomposition arranged in the process gas downstream of the catalytic NHoxidation and upstream of the absorption tower in the flow direction and a catalyst bed for NOreduction and effecting a further decrease in the amount of NO arranged in the tailgas downstream of the absorption tower in the flow direction,

[object Object]

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 (), a reaction zone () comprising at least one catalyst () and an exit zone () for the product gas are described. The reactors, at least in the area of the entry zone (), have means, for example insulating jackets () and/or devices for the transport of cooling agents, which decrease the transport of heat produced in the reaction zone () into the entry zone () 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 () and/or wherein the inner walls of the reactor, at least in the area of the entry zone (), are elaborated from inert material. The feed gas enters into the entry zone () as a homogeneous gas mixture with respect to its substance composition via one or more feed lines (). The reactors can especially be employed for ammonia oxidation, for example in nitric acid plants, in which transition metal catalysts preferably elaborated in honeycomb form with smaller cross sections than the customarily employed platinum gauzes are used.

Device and process for catalytic gas phase reactions and use thereof

Disclosed herein is a device and method for lowering the content of NOand NO in gases. The device comprises a container having therein two reaction steps connected in series. The first step removes NO(DeNOstage) by reducing NOwith a nitrogen-containing reducing agent. Downstream thereof, the second step removes NO by catalytic decomposition of NO to Nand O(DeNO stage). Each step comprises one or more catalyst beds through which flows gas to be purified. The catalyst bed of the DeNOstage containing zeolites doped with transition metals, including lanthanides. The at least one catalyst bed of the DeNO-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 NOand NO-containing gas is further disposed upstream of the DeNOstage.

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

Device and method for catalytic gas phase reaction and the use thereof

Catalysts for the decomposition of NO 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.

A method and device for removal of NO 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.

Removal of laughing gas in nitric acid production

The method comprises passing an NO- and NO-containing gas over a sequence of two catalyst beds, adding reducing agents for NOand for NO between the catalyst beds in such an amount that not only NObut also a predetermined proportion of NO is reduced. The reaction conditions are set so that the NO content of the gas is reduced by not more than 95%, based on the NO 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 NObut also chemical reduction of NO occurs in the second catalyst bed so that the NO content of the gas is reduced by at least 50%, based on the NO content at the entrance of the second catalyst bed.

Method for reducing the nitrogen oxide concentration in gases

A process is described for reducing the NOconcentration and NO 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 NOcontent and the second stage the NO content of the gas, the NO/NO 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.

The disclosure involves a method for reducing the content of NOand NO in gases. The method includes the conduction of a gas containing NO and NOover a series of two catalyst beds containing of one or more zeolites charged with iron followed by the: addition of a reduction agent for NObetween the catalyst beds. The first catalyst bed reaction zone is used to degrade the NO and the catalyst bed second reaction zone reduces the NOand breaks down at least part of the remaining NO. The inventive device comprises at least one radially traversed catalyst bed.

A process for reducing the content of NOand NO 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 NO- and NO-containing gas in at least the amount required for complete reduction of the NO; b) addition of a hydrocarbon, of carbon monoxide, of hydrogen, or of a mixture of one or more of these gases to the NO- and NO-containing gas for the reduction of the NO; and c) introduction of the gas mixture into at least one reaction zone at temperatures of up to 450&#xb0; 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.

Growing community of inventors

Meschede, Germany

Meinhard Schwefer