EP0805712A1 - Reduction catalytique selective des oxydes d'azote - Google Patents

Reduction catalytique selective des oxydes d'azote

Info

Publication number
EP0805712A1
EP0805712A1 EP96900482A EP96900482A EP0805712A1 EP 0805712 A1 EP0805712 A1 EP 0805712A1 EP 96900482 A EP96900482 A EP 96900482A EP 96900482 A EP96900482 A EP 96900482A EP 0805712 A1 EP0805712 A1 EP 0805712A1
Authority
EP
European Patent Office
Prior art keywords
oxide
catalyst
nitrogen
mole
catalyst comprises
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
EP96900482A
Other languages
German (de)
English (en)
Inventor
Raj Narain Pandey
Kebir Ratnani
Raghunandan Lal Varma
Rupesh Narain Pandey
David Elkaim
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.)
Gaz Metro LP
Original Assignee
Pandey Raj Narain
Gaz Metro LP
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
Priority claimed from CA002141734A external-priority patent/CA2141734C/fr
Application filed by Pandey Raj Narain, Gaz Metro LP filed Critical Pandey Raj Narain
Publication of EP0805712A1 publication Critical patent/EP0805712A1/fr
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—Nitrogen oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—Nitrogen oxides
    • B01D53/8628—Processes characterised by a specific catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/70—Organic acids

Definitions

  • the present invention pertains to improvements in the emission control of environmentally harmful and regulated nitrogen oxides (NO x ) which are produced in a variety of processes such as the combustion of fossil fuels. More particularly, the invention relates to an improved process for the selective catalytic reduction of nitrogen oxides to nitrogen.
  • NO x environmentally harmful and regulated nitrogen oxides
  • Atmospheric pollution caused by N0 X emissions has become a matter of growing global concern in recent years.
  • Nitrogen oxides contribute to acid rain and photochemical smog, and can cause respiratory problems. It is now recognized that the ground-level ozone is formed in the atmosphere through a photochemical reaction not only from volatile organic compounds but also from oxides of nitrogen.
  • the main sources of NO x emissions in industrialized countries are transportation, electric utilities, and industrial boilers. Much of the NO x is a product of combustion of fossil fuels such as coal, oil or gas.
  • Known catalytic systems which are able to catalyze effectively the above N0 X reduction reactions using NH3 are supported noble metals, supported base metal oxides and zeolites.
  • Noble metal catalysts such as those based on Pt, Rh, Ru or Pd supported on AI2O3 or other carriers, which are used widely in catalytic converters for automobile-exhaust NO x reduction, are usually not considered for flue gas treatment due to several drawbacks. These drawbacks include high cost, susceptibility to SO2 poisoning and substantial reduction of the catalytic activity at high temperatures or in the presence of excess oxygen due to accumulation of adsorbed oxygen.
  • Catalysts based on vanadia or tungsten-vanadia as active components supported on porous anatase-type titania are currently known to be most promising for the selective catalytic reduction of NO by NH3 mainly because of their high activity at low temperatures and good resistance to SO2 poisoning. These catalysts are presently used in many commercial installations.
  • ammonia slip Another serious disadvantage with the selective catalytic reduction of NO x by NH3 is the risk of unacceptably high levels of ammonia emission known as "ammonia slip".
  • ammonia slip can, in principle, be suppressed by lowering the reactor inlet NH3 NO x ratio. This however, adversely affects the NO x removal efficiency.
  • vanadia and tungsten-vanadia based catalysts exhibit resistance to SO2 poisoning, they catalyze oxidation of SO2 to SO3.
  • This latter compound (SO3) reacts with NH3 and H2O to form compounds such as NH4HSO4 and (NH4)2S2 ⁇ 7-
  • SO3 reacts with NH3 and H2O to form compounds such as NH4HSO4 and (NH4)2S2 ⁇ 7-
  • NH4HSO4 and (NH4)2S2 ⁇ 7- These compounds cause corrosion, plugging of the catalytic reactor and other parts of the system, and more undesirably, plugging of the pores of the catalysts.
  • Pore plugging of the catalyst eventually results in a deactivation of the catalyst at a fixed NH3/NO ratio and an increase of ammonia slip.
  • the loss in activity can be restored by increasing the inlet NH3/NO ratio.
  • increasing the NH3/NO ratio has the effect that ammonia slip also increases. Plugging of the catalyst pores and the reactor can also
  • a process for the selective catalytic reduction of nitrogen oxides to nitrogen which comprises reacting nitric oxide, nitrogen dioxide or a mixture thereof with a reducing agent consisting of an aliphatic carboxylic acid having 1 to 5 carbon atoms at a temperature ranging from about 250 to about 600°C, in the presence of a catalyst comprising a metal oxide selected from the group consisting of vanadium oxide, copper oxide, nickel oxide and iron oxide, the catalyst being supported on a porous carrier.
  • the above defined catalysts used in the RC00H- based selective catalytic reduction according to the invention are effective in promoting reactions (1) to (4) and suppressing the side reaction (11).
  • the loading of metal oxide on the support may vary in the range of about 5 to about 50 mole % , and more preferably in the range of about 8 to about 20 mole %.
  • the total (BET) surface area of the catalyst may vary in the range of about 50 to about 500 m ⁇ /g, and more preferably in the range of about 100 to about 300 m 2 /g.
  • the reaction is preferably carried out at a temperature of about 450 to about 500°C.
  • nitrogen or water vapor is admixed with the reducing agent.
  • the process of the invention enables one to substantially completely reduce NO x to harmless 2 in an efficient, environmentally friendly and cost- effective manner.
  • Figure 1 is a flow diagram of a process for the selective reduction of nitrogen oxides according to the invention.
  • the N0 X containing gaseous mixture produced in the fuel burner 10 by the combustion of fuel and discharged via line 12 is passed through a heat exchanger 14 for recovering most of the heat generated by the fuel combustion and lowering the temperature of the gas stream to about 250-600°C, and then sent to a catalytic converter 16 containing a fixed bed of a vanadium oxide, copper oxide, nickel oxide or iron oxide based catalyst.
  • a catalytic converter 16 containing a fixed bed of a vanadium oxide, copper oxide, nickel oxide or iron oxide based catalyst.
  • the N0 X containing gas stream enters into the converter 16, it is mixed with a reducing gas stream which is fed via feed line 18 and contains, as a reducing agent, an aliphatic carboxylic acid having 1 to 5 carbon atoms in admixture with nitrogen and water vapor.
  • the resulting gaseous mixture is passed through the catalyst bed maintained at a temperature of 250-600°C and reacted with the reducing agent.
  • the effluent stream which is discharged via line 20 and is free of N0 X contaminants is passed through a heat exchanger 22 for recovering useful heat and then through a stack 24 before being discharged at a regulatory height to the natural environment.
  • a V2 ⁇ 5 ⁇ -Al2 ⁇ 3 catalyst containing 10 mole % V2O5 was prepared by impregnating -AI2O3 (10 g) with a solution of oxalic acid (4.0 g) and ammonium metavanadate (2.34 g) in distilled water (50 ml). The impregnation was carried out by adding the V2O5/ -AI2O3 to the solution followed by mixing and water evaporation. The impregnated material was further dried in an oven at 120°C for 8 hours and calcined in a muffle furnace at 500°C for 2 hours. The BET surface area of the catalyst was 175 rn ⁇ /g.
  • a quartz microreactor was packed with 0.3 g of the above catalyst and placed in a continuous flow reactor.
  • a gaseous mixture containing nitric oxide and acetic acid was passed through the downflow reactor at a flow rate of 70 ml/min.
  • the molar composition of the feed gaseous mixture was as follows: 0.106% NO, 0.28% acetic acid, 2.15% water vapor and balance nitrogen.
  • the reactor temperature was maintained at 435°C.
  • N.D. Not Detected NO x Detection Limit - 50 ppb
  • concentration of nitric oxide was reduced from 1060 ppm to 3.9 ppm, indicating a conversion of 99.6%.
  • formation of other oxides of nitrogen such as NO2 or N2O was not detected.
  • Example 2 The same feed mixture as in Example 1 was passed through a microreactor packed with 0.3 g of a V2O5/7- AI2O3 catalyst containing 10 mole % V2O5, at 70 ml/min. flow rate. The reactor temperature was maintained at 445°C. The composition of the reactor effluent was analyzed in the same manner as in Example 1. The concentration of NO x in the reactor effluent is reported in Table 2.
  • a catalyst consisting of a ZSM-5 type zeolite in protonated form having a Si ⁇ 2/Al2 ⁇ 3 ratio of 36 was prepared by crystallizing silica rich gels containing tetrapropyl ammonium bromide as template, following the procedure outlined in US Patent N° 3,702,886.
  • the BET surface area of this catalyst was 376 rn ⁇ /g.
  • a gaseous mixture containing 0.15 mole % nitric oxide, 0.31 mole % acetic acid, 0.95 mole % water vapor and 98.59 mole % nitrogen was passed through a microreactor packed with 0.15 g of the zeolite catalyst at a flow rate of 45 ml/min. The reactor temperature was maintained at 500°C.
  • the reactor effluent was analyzed under steady state conditions.
  • the concentration of nitric oxide in the reactor effluent was 0.14%, indicating a NO conversion of only 4.7%. This is much lower compared to 99% conversion obtained using V2O5/7- AI2O3 and CuO- iO/ ⁇ Al2 ⁇ 3 catalysts under similar conditions.

Landscapes

  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Catalysts (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

On réalise la réduction catalytique sélective des oxydes d'azote en azote en faisant réagir de l'oxyde nitrique, du dioxyde d'azote ou un mélange de ceux-ci avec un agent réducteur constitué d'un acide carboxylique aliphatique ayant de 1 à 5 atomes de carbone, à une température située entre 250 DEG C environ et 600 DEG C environ, en présence d'un catalyseur constitué d'un oxyde de métal choisi dans le groupe constitué par l'oxyde de vanadium, l'oxyde de cuivre, l'oxyde de nickel et l'oxyde de fer, le catalyseur étant sur un support poreux. Le procédé selon l'invention permet une réduction sensiblement complète de NOx en N2 (qui est inoffensif), d'une manière efficace, peu coûteuse et sans danger pour l'environnement.
EP96900482A 1995-01-25 1996-01-19 Reduction catalytique selective des oxydes d'azote Ceased EP0805712A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
CA002141734A CA2141734C (fr) 1995-01-25 1995-01-25 Reduction catalytique selective d'oxydes d'azote
CA2141734 1995-01-25
PCT/CA1996/000027 WO1996022828A1 (fr) 1995-01-25 1996-01-19 Reduction catalytique selective des oxydes d'azote

Publications (1)

Publication Number Publication Date
EP0805712A1 true EP0805712A1 (fr) 1997-11-12

Family

ID=4155174

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96900482A Ceased EP0805712A1 (fr) 1995-01-25 1996-01-19 Reduction catalytique selective des oxydes d'azote

Country Status (7)

Country Link
EP (1) EP0805712A1 (fr)
JP (1) JPH10512806A (fr)
AU (1) AU698950B2 (fr)
BR (1) BR9606854A (fr)
HU (1) HUP9801723A2 (fr)
NO (1) NO973320L (fr)
NZ (1) NZ298726A (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100366342C (zh) * 2004-12-17 2008-02-06 南化集团研究院 一种低温下还原脱除氮氧化物催化剂及其制备方法
CN115121110A (zh) * 2021-03-24 2022-09-30 中国石油化工股份有限公司 一种催化一氧化二氮分解的方法

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4231318A (en) * 1978-07-03 1980-11-04 The Black Clawson Company Dual blade coater
JPH02233124A (ja) * 1989-03-03 1990-09-14 Hitachi Zosen Corp 窒素酸化物の除去方法
JP3276191B2 (ja) * 1993-01-29 2002-04-22 三菱重工業株式会社 窒素酸化物の浄化方法

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9622828A1 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100366342C (zh) * 2004-12-17 2008-02-06 南化集团研究院 一种低温下还原脱除氮氧化物催化剂及其制备方法
CN115121110A (zh) * 2021-03-24 2022-09-30 中国石油化工股份有限公司 一种催化一氧化二氮分解的方法
CN115121110B (zh) * 2021-03-24 2023-08-08 中国石油化工股份有限公司 一种催化一氧化二氮分解的方法

Also Published As

Publication number Publication date
NO973320D0 (no) 1997-07-18
AU698950B2 (en) 1998-11-12
NZ298726A (en) 1998-11-25
BR9606854A (pt) 1997-11-25
HUP9801723A2 (hu) 1998-10-28
AU4428296A (en) 1996-08-14
NO973320L (no) 1997-09-05
JPH10512806A (ja) 1998-12-08

Similar Documents

Publication Publication Date Title
US5612010A (en) Selective catalytic reduction of nitrogen oxides
Qi et al. Low-temperature SCR of NO with NH3 over USY-supported manganese oxide-based catalysts
US5149512A (en) Catalytic reduction of NOx using methane in the presence of oxygen
EP0491726B1 (fr) Procede combine sncr (non catalytique) et scr (catalytique) de reduction des oxydes azotes
US5260043A (en) Catalytic reduction of NOx and carbon monoxide using methane in the presence of oxygen
AU778960B2 (en) Method for removal of NOX and N2O
US4080426A (en) Reduction of nitric oxide using catalysts pretreated with selenium
US20060159607A1 (en) Catalyst and method for reduction of nitrogen oxides
CN108993476B (zh) 金属氧化物-钒酸盐/TiO2催化剂及其制备方法和应用
EP0652040B1 (fr) Procédé et catalyseur pour la réduction de NOx dans des gaz de combustion
AU698950B2 (en) Selective catalytic reduction of nitrogen oxides
KR20220156030A (ko) 공정 오프가스에서 NOx 및 산화이질소의 제거 방법
JPH0587291B2 (fr)
KR100382051B1 (ko) 이산화황을 포함하고 있는 배가스 중의 질소산화물을저온에서 제거하기 위한 선택적 환원촉매
WO1998024534A1 (fr) Reduction catalytique selective d'oxydes d'azote
US5869013A (en) Process and catalyst for reducing Nox in exhaust combustion gases
KR20220112227A (ko) 배기가스 처리장치
MXPA97005622A (en) Catalytic selective reduction of nitrog oxides
JP2004074139A (ja) 排ガス浄化触媒及び浄化方法
US5078982A (en) Reduction of nitrogen oxide in effluent gases using formaldehyde
Coppola et al. De-NOx SCR: Catalysts and Process Designs in the Automotive Industry
KR20240004113A (ko) 가스터빈 복합화력 발전소에서 기동 및 정지시 및 정상운전시발생하는 질소산화물 제거 촉매
Moffat Department of Chemistry and Guelph-Waterloo Centre for Graduate Work in Chemistry
HK1024651A (en) Catalyst for reducing nox in combustion exhaust gases
KR20050019708A (ko) 배기가스 정화용 촉매 및 배기 가스 정화 방법

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19970815

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB GR IE IT LI LU MC NL PT SE

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: GAZ METROPOLITAIN AND COMPANY, LIMITED PARTNERSHIP

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

17Q First examination report despatched

Effective date: 20001228

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION HAS BEEN REFUSED

18R Application refused

Effective date: 20010831