Uhde Gmbh

Thyssenkrupp Industrial Solutions Ag

Thyssen Krupp Ag

Thyssenkrupp Uhde Gmbh

Unde Gmbh

Michael Groves

Meinhard Schwefer

Rolf Siefert

Jürgen Fuchs

Rainer Maurer

Klaus Ruthardt

Bernhard Hündgen

Jurgen Fuchs

Christian Perbandt

Jens Mathiak

Paul Kern

Bernhard Hundgen

Juergen Fuchs

Bernhard Huendgen

Bernhard HÜNDGEN

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 NHoxidation according to 4NH+5O&#x2192;4NO+6HO revealed that an optimum mode of operation of an NHburner in an HNOplant is not to be achieved by maintenance of a constant gauze temperature of the catalyst gauze by automatic setting of the NH:air ratio. Rather, there is an optimum temperature for each process condition that should be set not by changing the NH:air ratio but instead by altering the temperature of the NH/air mixed gas before contact with the catalyst gauzes.

Method for the catalytic oxidation of ammonia gas

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

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

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

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

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.

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Gevelsberg, Germany

Michael Groves