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WO1998057887A1 - Oxydation ammoniacale - Google Patents

Oxydation ammoniacale Download PDF

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Publication number
WO1998057887A1
WO1998057887A1 PCT/GB1998/001649 GB9801649W WO9857887A1 WO 1998057887 A1 WO1998057887 A1 WO 1998057887A1 GB 9801649 W GB9801649 W GB 9801649W WO 9857887 A1 WO9857887 A1 WO 9857887A1
Authority
WO
WIPO (PCT)
Prior art keywords
catalyst
reflector
ammonia
catalyst bed
oxidation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/GB1998/001649
Other languages
English (en)
Inventor
David Graham Shipley
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Imperial Chemical Industries Ltd
Original Assignee
Imperial Chemical Industries Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Imperial Chemical Industries Ltd filed Critical Imperial Chemical Industries Ltd
Priority to AU77816/98A priority Critical patent/AU7781698A/en
Publication of WO1998057887A1 publication Critical patent/WO1998057887A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/20—Nitrogen oxides; Oxyacids of nitrogen; Salts thereof
    • C01B21/24—Nitric oxide (NO)
    • C01B21/26—Preparation by catalytic or non-catalytic oxidation of ammonia
    • C01B21/28—Apparatus
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/008—Details of the reactor or of the particulate material; Processes to increase or to retard the rate of reaction
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/02—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
    • B01J2208/00008—Controlling the process
    • B01J2208/00017—Controlling the temperature
    • B01J2208/00477—Controlling the temperature by thermal insulation means
    • B01J2208/00495—Controlling the temperature by thermal insulation means using insulating materials or refractories
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
    • B01J2208/00008—Controlling the process
    • B01J2208/00017—Controlling the temperature
    • B01J2208/0053—Controlling multiple zones along the direction of flow, e.g. pre-heating and after-cooling

Definitions

  • This invention relates to ammonia oxidation.
  • Ammonia oxidation is widely employed in the manufacture of nitric acid and hydrogen cyanide.
  • ammonia is oxidised with air to nitric oxide
  • hydrogen cyanide a mixture of ammonia and methane (often as natural gas) is oxidised with air.
  • the gas mixture is passed at an elevated temperature over a catalyst to effect the oxidation.
  • Side reactions such as the formation of nitrogen or nitrous oxide, are undesirable. Consequently, in addition to good activity, the catalyst is required to have a good selectivity.
  • the oxidation reaction is exothermic: as the heated gas mixture passes through the catalyst, the oxidation reaction proceeds with the evolution of heat, causing the temperature of both the gas mixture and the catalyst to increase until a steady state condition is reached.
  • the selectivity of the reaction depends on the catalyst temperature, and for any given operating conditions, i.e. gas composition, catalyst, catalyst age, flow rate etc. there is generally an optimum temperature.
  • the catalyst temperature may be controlled by modification of one or more of the process variables, for example the temperature to which the gas mixture is pre-heated and/or the proportion of ammonia in the gas mixture.
  • the present invention provides for the oxidation of ammonia comprising passing a mixture of ammonia and an oxygen containing gas preheated to an elevated temperature through at least one bed of a catalyst effective for the oxidation of ammonia wherein, in order to render the catalyst temperature more uniform, the gas mixture is passed through a perforate reflector disposed upstream of the catalyst bed, said reflector being effective to reflect heat radiated from the inlet face of the catalyst bed back towards the catalyst bed.
  • the catalyst may be platinum, optionally alloyed with other precious metals such as rhodium, in the form of meshes or gauzes formed from the metal wire.
  • the catalyst may be in the form of pellets, extrudates or granules of an oxidic material such as a composition containing cobalt oxide.
  • lanthana/ceria/cobalt oxide compositions of the general formula La 1 . x Ce x Co0 3 (where x is from 0 to 1 ) made by a specified co-precipitation route as ammonia oxidation catalysts.
  • Oxidic catalysts preferably contain at least one mixed oxide phase containing cobalt and at least one element A selected from rare earths and yttrium, said cobalt and element A being in such proportions that the element A to cobalt atomic ratio is in the range 0.8 to 1.2, particularly 1.0 to 1.2.
  • at least one element selected from yttrium, cerium, lanthanum, neodymium, and praseodymium is used as part or all of element A.
  • Element A may comprise a mixture of at least one variable valency element Vv selected from cerium and praseodymium and at least one non-variable valency element Vn selected from yttrium and the non-variable valency rare earth elements such as lanthanum or neodymium.
  • Vv variable valency element
  • Vn non-variable valency element
  • the atomic proportions of variable valency element Vv to non-variable valency element Vn is in the range 0 to 1 , particularly 0 to 0.3.
  • Such oxidic catalysts may be in a form wherein the amount of oxygen is non-stoichiometric. This arises from the variable valency of cobalt and also of any variable valency rare earth present as part, or all, of element A.
  • a radiation reflector is disposed upstream of the catalyst to reflect heat radiated from the inlet face of the catalyst back to the catalyst. In this way heat loss from the inlet face of the catalyst is minimised and so the catalyst temperature is more uniform.
  • the reflector is preferably a perforate plate disposed just upstream of the catalyst. The perforations should be of sufficient number and size that the reflector presents only an insignificant impedance to the flow of the gas mixture therethrough, but, on the other hand they should only form a minor proportion of the area of the reflector so that a substantial amount of the radiation is reflected.
  • the perforations are in the form of louvres so that essentially all the area of the reflector acts to reflect the radiated heat.
  • the reflector may also act as a diffuser to ensure even distribution of the gas mixture through the catalyst bed.
  • the reflector is preferably positioned between 1 and 30 cm above the top of the catalyst bed.
  • FIG. 1 there is shown a vessel 1 having an inlet port 2 and an outlet port 3. Disposed across the vessel are catalyst beds 4, 5 each composed of a wad of gauzes formed from a platinum/rhodium alloy wire . Upstream of the bed 4 nearest the inlet port is disposed a reflector plate 6 formed from a suitable heat resistant metal such as Incalloy. A plurality of louvres 7 are provided in the reflector plate 6.
  • the reflector consists of a pair of metal plates 8, 9 spaced one above the other. Each plate is perforate so as to allow passage of the reactants through the plates, but the perforations are staggered so that heat radiated from the catalyst bed passing through the perforations of the lower plate is reflected by the lower surface of the upper plate.
  • the oxidation process may be operated at temperatures of 800-1000 C, particularly 850-950°C, pressures of 1 to 15 bar abs., with ammonia in air concentrations of 5-15%, often about 10%, by volume.
  • the selectivity tends to increase as the space velocity is increased, and so high space velocity
  • velocities greater than 1.5 x 10 h , are desirable.
  • the space velocity depends on the linear velocity of the feed gas (at NTP) and the depth of the catalyst bed.
  • Linear gas velocities conventionally employed in commercial atmospheric pressure ammonia oxidation processes are usually in an excess of 2000 m/h, and typically are in the range 2500-8000 m/h, preferably 4000-6000 m/h.
  • Commercial processes operating at elevated pressures tend to employ considerably higher linear gas velocities, for example 30000-40000 m/h.
  • the bed depth it is desirable for the bed depth to be less than 50 mm. For example with a bed of depth 20 mm, at a

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Catalysts (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

L'invention concerne un procédé qui permet d'assurer une meilleure uniformité de la température du catalyseur dans un procédé d'oxydation ammoniacale catalytique. Selon ce procédé, le mélange de réactifs préchauffés, à savoir, le gaz contenant de l'oxygène et de l'ammoniac, passe à travers un réflecteur perforé placé en amont du lit du catalyseur. Ce réflecteur permet de réfléchir avec efficacité la chaleur irradiée à partir de la face d'entrée du lit du catalyseur pour la renvoyer vers le lit du catalyseur.
PCT/GB1998/001649 1997-06-17 1998-06-04 Oxydation ammoniacale Ceased WO1998057887A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU77816/98A AU7781698A (en) 1997-06-17 1998-06-04 Ammonia oxidation

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9712444.0 1997-06-17
GBGB9712444.0A GB9712444D0 (en) 1997-06-17 1997-06-17 Ammonia oxidation

Publications (1)

Publication Number Publication Date
WO1998057887A1 true WO1998057887A1 (fr) 1998-12-23

Family

ID=10814187

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1998/001649 Ceased WO1998057887A1 (fr) 1997-06-17 1998-06-04 Oxydation ammoniacale

Country Status (4)

Country Link
AU (1) AU7781698A (fr)
GB (1) GB9712444D0 (fr)
TW (1) TW426637B (fr)
WO (1) WO1998057887A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7563419B2 (en) 2002-07-03 2009-07-21 Yara International Asa Method and device for supporting catalyst gauzes in an ammonia oxidation burner
US8734728B2 (en) 2011-06-20 2014-05-27 Honeywell International Inc. NH3 oxidizer gas distributor
US9878309B2 (en) 2013-12-06 2018-01-30 Danmarks Tekniske Universitet Catalyst for ammonia oxidation

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3462243A (en) * 1967-11-13 1969-08-19 Belge Produits Chimiques Sa Process and burner for the conversion of ammonia into oxides of nitrogen
US4170455A (en) * 1976-03-11 1979-10-09 Rockwell International Corporation Gas monitoring method and apparatus therefor
EP0275681A1 (fr) * 1986-12-23 1988-07-27 Johnson Matthey Public Limited Company Bloc catalyseur pour l'oxydation de l'ammoniac
DE3731988A1 (de) * 1987-09-23 1989-04-06 Steinmueller Gmbh L & C Reaktor fuer die behandlung eines gases mittels eines katalysators mit grosser anstroemflaeche

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3462243A (en) * 1967-11-13 1969-08-19 Belge Produits Chimiques Sa Process and burner for the conversion of ammonia into oxides of nitrogen
US4170455A (en) * 1976-03-11 1979-10-09 Rockwell International Corporation Gas monitoring method and apparatus therefor
EP0275681A1 (fr) * 1986-12-23 1988-07-27 Johnson Matthey Public Limited Company Bloc catalyseur pour l'oxydation de l'ammoniac
DE3731988A1 (de) * 1987-09-23 1989-04-06 Steinmueller Gmbh L & C Reaktor fuer die behandlung eines gases mittels eines katalysators mit grosser anstroemflaeche

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
B. ELVERS ET AL.: "Ulmann's Encyclopedia of industrial chemistry; vol A17, 5th Ed.", 1991, VCH, WEINHEIM (DE), XP002077606 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7563419B2 (en) 2002-07-03 2009-07-21 Yara International Asa Method and device for supporting catalyst gauzes in an ammonia oxidation burner
US8734728B2 (en) 2011-06-20 2014-05-27 Honeywell International Inc. NH3 oxidizer gas distributor
EP2723489A4 (fr) * 2011-06-20 2015-05-13 Honeywell Int Inc Nh3-oxidationsgasverteiler
US9878309B2 (en) 2013-12-06 2018-01-30 Danmarks Tekniske Universitet Catalyst for ammonia oxidation

Also Published As

Publication number Publication date
TW426637B (en) 2001-03-21
GB9712444D0 (en) 1997-08-13
AU7781698A (en) 1999-01-04

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