Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
  • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
  • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
  • F01N3/023—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles
  • F01N3/025—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles using fuel burner or by adding fuel to exhaust
  • F01N3/0253—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles using fuel burner or by adding fuel to exhaust adding fuel to exhaust gases
• • 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
  • B01D53/32—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 by electrical effects other than those provided for in group B01D61/00
• • 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
  • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
• • 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
  • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
  • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
  • B01D53/9404—Removing only nitrogen compounds
  • B01D53/9409—Nitrogen oxides
  • B01D53/9431—Processes characterised by a specific device
• • 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
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
  • B01J19/087—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
  • B01J19/088—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
  • F01N13/009—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
  • F01N13/009—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series
  • F01N13/0097—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series the purifying devices are arranged in a single housing
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
  • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
  • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
  • F01N3/023—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles
  • F01N3/0231—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles using special exhaust apparatus upstream of the filter for producing nitrogen dioxide, e.g. for continuous filter regeneration systems [CRT]
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
  • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
  • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
  • F01N3/033—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices
  • F01N3/035—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices with catalytic reactors, e.g. catalysed diesel particulate filters
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
  • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
  • F01N3/0892—Electric or magnetic treatment, e.g. dissociation of noxious components
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2259/00—Type of treatment
  • B01D2259/80—Employing electric, magnetic, electromagnetic or wave energy, or particle radiation
  • B01D2259/818—Employing electrical discharges or the generation of a plasma
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
  • B01J2219/0803—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
  • B01J2219/0805—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
  • B01J2219/0807—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges involving electrodes
  • B01J2219/0809—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges involving electrodes employing two or more electrodes
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
  • B01J2219/0803—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
  • B01J2219/0805—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
  • B01J2219/0845—Details relating to the type of discharge
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
  • B01J2219/0803—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
  • B01J2219/0805—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
  • B01J2219/0845—Details relating to the type of discharge
  • B01J2219/0849—Corona pulse discharge
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
  • B01J2219/0873—Materials to be treated
  • B01J2219/0875—Gas
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
  • B01J2219/0873—Materials to be treated
  • B01J2219/0892—Materials to be treated involving catalytically active material
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N2240/00—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being
  • F01N2240/20—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being a flow director or deflector
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N2240/00—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being
  • F01N2240/28—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being a plasma reactor
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N2610/00—Adding substances to exhaust gases
  • F01N2610/01—Adding substances to exhaust gases the substance being catalytic material in liquid form
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N2610/00—Adding substances to exhaust gases
  • F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N2610/00—Adding substances to exhaust gases
  • F01N2610/03—Adding substances to exhaust gases the substance being hydrocarbons, e.g. engine fuel
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
  • F23J2215/00—Preventing emissions
  • F23J2215/10—Nitrogen; Compounds thereof
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
  • F23J2219/00—Treatment devices
  • F23J2219/20—Non-catalytic reduction devices
  • F23J2219/201—Reducing species generators, e.g. plasma, corona

Definitions

• the present invention relates to reactors for the plasma-assisted processing of gaseous media and in particular to plasma assisted catalytic reactors for the reduction of the emission of carbonaceous and nitrogenous oxide combustion products from the exhausts of internal combustion engines.
• precipitation In a broader context, the precipitation of charged particulate matter by electrostatic forces also is known. However, in this case, precipitation usually takes place upon large planar electrodes or metal screens.
• GB patent 2,274,412 discloses a method and apparatus for removing particulate and other pollutants from internal combustion engine exhaust gases, in which the exhaust gases are passed through a bed of charged pellets of material, preferably ferroelectric, having high dielectric constant.
• pellets of material preferably ferroelectric, having high dielectric constant.
• N0 2 Although nitric oxide is produced from the oxidation of carbon by nitrogen dioxide this reaction also has a pathway for the production of nitrogen as well as nitric oxide that is highlighted in US patent specification 4 902 487 (1990) by Cooper et al. In particular, there is discussed the use of a platinum based catalyst to oxidise NO initially present in the exhaust gases to N0 2 . Particulate carbon which is not also oxidised by the platinum catalyst is collected on a soot trap, for example a ceramic honeycomb. N0 2 then adsorbs onto the trapped particulates and oxidises the trapped particulate carbon.
• the oxidation rate can be enhanced by the presence of water adsorbed on the material of the soot trap, and that the presence of a carbon combustion catalyst derived from an alkali metal salt such as lithium nitrate can lower the temperature required for the combustion of carbon in the presence of nitrogen dioxide.
• a carbon combustion catalyst derived from an alkali metal salt such as lithium nitrate
• the use of alkali metal salts as combustion catalysts also is described in patent specification GB 2 232 613 B.
• Eolys a cerium oxide-based additive for diesel fuel that is injected from an additional tank at the rear of the vehicle into the diesel tank.
• the Eolys reduces the temperature at which carbonaceous particulates trapped on a filter combust from 550°C to 450°C.
• the Eolys reagent is used in conjunction with a post-combustion phase fuel injection that raises the exhaust gas temperature by 200- 250°C and an oxidation catalyst before the trap that increases the exhaust temperature by a further 100°C to between 450-500°C allowing regeneration to take place (FT Automotive Environment Analyst, Issue 52, May 1999, page 27, EP 0 488 831, EP 0 661 429, FR 2668203).
• a method of producing nitrogen dioxide from nitric oxide contained in a gaseous medium comprising the operation of subjecting the gaseous medium to the action of a non- thermal plasma.
• the nitrogen dioxide thus produced is utilised to oxidise carbon.
• Any nitric oxide produced in this reaction together with any residual nitrogenous oxide in the exhaust gases that is not initially converted in the non-thermal plasma to nitrogen dioxide is then reduced to nitrogen.
• Nitric oxide derived from the reaction of carbon with nitrogen dioxide which is produced in the fuel combustion process and not by selective oxidation in a plasma, thus also undergoes reduction to nitrogen according to the present invention.
• a non-thermal plasma is a plasma in which the majority of the electrical energy input goes into the production of energetic electrons and is characterised by high electron mean energies while the gas remains at near ambient temperature and pressure (BM Penetrante, 'Power consumption of non- thermal plasma reactors' in Emerging Technologies in Hazardous Waste Management VI, American Chemical Society, September 19-21, 1994, Page 195).
• the non- thermal plasma can be generated in a number of ways, for example it can be generated in a packed ferroelectric bed reactor similar to that described in specification GB 2 274 412, a pulsed corona discharge reactor, a silent electric discharge reactor (also known as a dielectric barrier reactor), a dielectric barrier reactor filled with a bed of gas permeable dielectric material, or a surface discharge reactor.
• Non-thermal plasma reactors have been known for a considerable time.
• dielectric barrier reactors have been used for over a hundred years, described initially by W von Siemens to produce ozone (Annalen der Physik und Chemie, volume 102, 66-122, 1857).
• the Siemens tube consisted of a narrow annular discharge gap between two coaxial glass cylinders. A 'silent discharge' was established by applying an alternating high voltage through the glass walls. Air or oxygen passing through the discharge was partially converted into ozone.
• Widespread use of dielectric barrier discharges began at the beginning of the 20 th century when large scale application to water purification using ozone was introduced in several cities including Nice (1907) and St Louis (1910).
• Non-thermal plasma reactors such as dielectric barrier discharge reactors have also been used for other applications in plasma chemistry. These include synthesis of inorganic and organic compounds, generation of excimers to produce ultra violet radiation, detoxification of hazardous wastes such as volatile organic compounds and the removal of nitrogen and sulphur oxides from the flue gases of large scale burning processes. Modern ozone generators have been described by Kogelschatz (Proceedings of the 10 th International Conference on Gas Discharges and their Applications, 1992) while a reactor for the remediation of volatile organic compounds is described by Evans et al (Journal of Applied Physics, volume 74, 5378-5386, 1993). Treatment of nitrogen oxides in a dielectric barrier discharge reactor is described by McLarnon and Penetrante (Society of Automotive Engineers paper 98-2434, October 1998).
• a method of removing nitrogenous oxides and carbonaceous particulates from the exhaust gases from an internal combustion engine supplied with a combustion fuel comprises the operations of passing the exhaust gases through a reactor chamber, the exhaust gases containing hydrocarbon either added separately or residually derived from said combustion fuel, exciting a non- thermal plasma therein, characterised by utilising nitrogen dioxide produced in the exhaust gases by the action of the non-thermal plasma upon nitric oxide contained in the exhaust gases to oxidise the carbonaceous particulates contained in the exhaust gases.
• the step of reducing to nitrogen any nitric oxide produced by the oxidation of the carbonaceous particulates together with any nitric oxide remaining in the exhaust having not been converted- to nitrogen dioxide in the plasma is included.
• oxidation of nitric oxide to nitrogen dioxide in a non- thermal plasma is enhanced in the presence of a hydrocarbon in the gaseous phase (see B.M. Penetrante et al, Paper number SAE 982508, 1988, Figure 2)
• the hydrocarbon may be that which is present in the exhaust gases from the fuel combustion processes or be added separately to the exhaust gases to enhance the selective oxidation reaction to nitrogen dioxide.
• the hydrocarbon may be in the form of the fuel as described in our publication WO 99/12638 published on 18 March 1999.
• the N0 2 produced in the plasma is adsorbed on the particulate carbon with which it reacts to produce carbon monoxide, carbon dioxide, nitrogen and NO.
• the oxidation of the carbonaceous particulates is facilitated by passing the excited exhaust gases through a filter element in which the particulate carbon becomes trapped.
• the filter element may be contained either in or outside the plasma forming region and may be ceramic material or, alternatively when outside the plasma forming region, may be metallic or polymeric
• the filter element can be in the form of spheres, pellets, extrudates , fibres, sheets, coils, granules, foams or honeycomb monolith. Combinations of one or more of the above can be used to create a filter structure with a non-uniform surface area and porosity, for example a graded porosity, when presented to the exhaust gas.
• the filter element may contain a coating of, be impregnated with or generally treated by for example ion exchange or doping or be made out of a carbon combustion catalyst for example cerium oxide or alkali metal doped lanthanum oxide-vanadium pentoxide or perovskite as described in our publication WO99/38603 published on 5 August 1999 to aid the regeneration of the filter.
• the fuel supplied to the internal combustion engine from which the exhaust gases come may contain a chemical additive for aiding combustion of carbonaceous particulates by nitrogen dioxide. In this case the additive, or a derivative of it formed on fuel combustion is present in the exhaust gases as they pass through the plasma.
• the chemical additive may be added separately and not be part of the fuel.
• the presence of a combustion catalyst in the fuel or on the filter can reduce the concentration of nitrogen dioxide required to be produced in the exhaust gases by the non-thermal plasma and aid efficiency.
• the temperature of the exhaust gases can be raised in a post -combustion phase through the combustion of additional fuel so as to raise the temperature of the filter, aid the regeneration of the filter and limit the power requirements for the generation of the plasma.
• the temperature of the exhaust gases can also be raisedjby the exothermic reactions on an oxidation catalyst.
• the resultant gas stream can then be mixed with a reductant such as a hydrocarbon vapour for example propene (C 3 H 6 ), passed through a second non-thermal plasma reactor and then over a catalyst, such as a metal -doped zeolite, which acts to reduce the NO to nitrogen; a non- zeolite catalyst such as alumina can be used.
• a catalyst such as a metal -doped zeolite, which acts to reduce the NO to nitrogen; a non- zeolite catalyst such as alumina can be used.
• the catalyst may be present in the plasma zone of the second reactor but can also be outside of the plasma zone and can be in the form of spheres, pellets, extrudates, fibres, sheets, coils, granules, foams, honeycomb monolith or as a coating on a foam or honeycomb monolith.
• Foams and monoliths can be ceramic, metallic or polymeric and examples of foams and monoliths include but are not limited to alumina, zirconia, titania, zeolite for foams and cordierite, alumina, zeolite and Fecralloy metal for honeycomb monoliths.
• the second plasma serves one or more or a combination of the following f nctions, the importance of which is subject to the choice of zeolite, metal dopant, dopant loading and other such factors when the catalyst is a zeolite that can be metal -exchanged, metal-doped or in the H- form.
• activation has been described in our publication W099/12638 filed on 26 August 1998.
• activated hydrocarbon we mean plasma activated hydrocarbon in which the activity of the hydrocarbon has been enhanced in a plasma by for example partial oxidation, free radical formation, ionisation and/or energy absorption (e.g. into vibrational or rotational modes).
• activated hydrocarbon we mean plasma activated hydrocarbon in which the activity of the hydrocarbon has been enhanced in a plasma by for example partial oxidation, free radical formation, ionisation and/or energy absorption (e.g. into vibrational or rotational modes).
• a reductant other than hydrocarbon may be used, in particular nitrogen containing species such as ammonia, urea, ammonium carbonate or cyanuric acid.
• a particularly useful catalyst is vanadium pentoxide-titanium dioxide.
• mixing with effluent can be made after the effluent has passed through the plasma forming region of the second reactor before contact with the catalyst.
• a reactor system for removing nitrogenous oxides and particulate carbon combustion products from the exhaust emissions of internal combustion engines comprising a first reactor chamber including means for establishing a non-thermal plasma therein into which hydrocarbon vapour or gas can be added in addition to any hydrocarbon vapour or gas present in the exhaust gases from the fuel combustion processes, a trap for carbonaceous particulates, means for passing the effluent from the first reactor chamber through the carbonaceous particulate trap that may be in or outside of the plasma zone, means for mixing the effluent from the carbonaceous particulate trap with a reductant that is either hydrocarbon or nitrogen containing species such as ammonia and passing the mixture through a second reactor chamber including means for establishing a non-thermal plasma therein and means for passing the activated mixture over a catalyst adapted to reduce nitric oxide to nitrogen.
• the catalyst may be in or outside of the plasma forming region and the reductant may be mixed with the effluent from the first reactor chamber after this efflu
• the plasma excited in the second reactor chamber also is of the non- thermal type.
• the means for establishing non-thermal plasmas in one, other or both of the reactor chambers may comprise a bed of gas permeable high dielectric and/or ferroelectric material contained between two electrodes, means for establishing a pulsed corona discharge in the reactor chamber concerned, means for establishing a silent electric discharge in the reactor chamber concerned, the combination of means for establishing a silent electric discharge with a gas permeable bed of dielectric material, or means for establishing a surface electric discharge in the reactor chamber concerned.
• a suitable catalyst for the reduction of nitrogenous oxides such as nitric oxide to nitrogen is an alkali metal exchanged zeolite Y, or silver aluminate.
• Other metal -exchanged or metal -doped zeolite material such as that known as Cu/ZSM-5, Fe/ZSM-5 or Co/ZSM-5 with or without catalyst promoting cations of cerium or lanthanum, zeolite beta, hydrogen exchanged zeolites such as H-ZSM-5 are also suitable materials.
• Suitable materials for the reduction of nitrogenous oxides to nitrogen are aluminas including alpha, gamma, chi and other crystalline phases, oxides of titanium, zirconium, cerium and vanadium, perovskites, spinels and mixtures of these materials.
• Metal doped inorganic oxides such as cobalt-doped aluminas are also suitable materials.
• Vanadium pentoxide-titanium dioxide is a particularly suitable catalyst when the reductant is a nitrogen containing species. Catalyst can however trap and activate the trapped carbon even when not in a plasma.
• a reactor system 100 for removing nitrogenous oxide and particulate carbon combustion products from the exhaust gases from internal combustion engines comprises, a first reactor 101 And a second reactor 102 in series with the first reactor, 101.
• the first reactor 101 has an inlet stub 103 and the second reactor 102 has an outlet stub 104 by means of which the reactor 100 can be incorporated into the exhaust system of an internal combustion engine which is not shown in the drawing.
• a chamber 105 which contains a means 106 for generating a plasma in exhaust gases entering the reactor 101 and a second chamber 107 containing a ceramic particulate filter bed 108.
• the particulate filter bed may also be contained in the plasma region thus avoiding the requirement for a second chamber.
• an inlet 121 is available for introducing additional hydrocarbon into the exhaust when insufficient residual hydrocarbon is present from the combustion fuel.
• the plasma generating means 106 is not shown in detail because it can take a number of forms.
• it can be a pellet bed device such as that disclosed in our patent GB 2 274 412, a pulsed corona discharge device such as that disclosed in our patent GB 2 282 738, a silent electric discharge producing device, a silent electric discharge device in association with a gas permeable bed of dielectric material, or a device for producing a surface electric discharge in the chamber 105 of the reactor 100.
• a proviso is that the material of the pellet bed, or similar should not be made of a material which acts to reduce higher oxides of nitrogen.
• a flow- smoothing baffle 109 is positioned between the chambers 105, 107 of the reactor 101.
• the plasma generator 106 is of a type which incorporates a gas permeable bed of dielectric material to assist the generation of a plasma- in the exhaust gases passing through the chamber 105, then its porosity should be such as to minimise the trapping of particulate carbonaceous combustion products in it.
• the second reactor, 102 also is divided into two chambers 110 and 111.
• the chamber 110 contains a plasma generator 112, which can be any of the types of plasma generator mentioned above, and the chamber 111 contains a permeable bed 113 of a catalyst adapted to reduce nitrogenous oxide to nitrogen.
• a flow smoother 114 is provided between the chambers 110, 111 of the reactor 102.
• a suitable catalyst is an alkali metal - exchanged zeolite Y or silver aluminate.
• Other metal - exchanged or metal doped zeolite material such as those known as Cu/ZSM-5, Fe/ZSM-5, Co/ZSM-5, zeolite beta and hydrogen exchanged zeolites such as H-ZSM-5 are suitable materials.
• aluminas including alpha, gamma, chi and other crystalline phases, oxides of titanium, zirconium, cerium and vanadium, perovskites, spinels and mixtures of these materials.
• Metal doped inorganic oxides such as cobalt-doped aluminas are also suitable materials.
• Vanadium pentoxide-titanium dioxide is a particularly suitable catalyst when a nitrogen containing reductant is used to replace hydrocarbon reductant.
• Catalyst can also be present in the second plasma region as a bed of spheres, pellets, extrudates, fibres, sheets, coils, granules, foams, honeycomb monolith or as a coating on a foam or honeycomb.
• Foams and monoliths can be ceramic, metallic or polymeric.
• a port 115 Upstream of the plasma generator 112 is a port 115 through which a gaseous hydrocarbon or nitrogen containing reductant can be added to the effluent from the reactor 101.
• the system operates as follows:
• Exhaust gases containing a mixture of nitrogen oxides and particulate carbonaceous combustion products pass through the plasma generator 106 in which NO contained in the exhaust gases is oxidised to N0 2 and this oxidation is enhanced by the presence of hydrocarbon in the exhaust from uncombusted fuel or additional hydrocarbon added to the exhaust.
• the N0 2 then oxidises carbon particulates trapped in the ceramic filter bed 108 to CO and C0 2 , being itself reduced ' to NO and N 2 in the process.
• the presence of a combustion catalyst in the fuel, injected separately or on the filter can reduce the requirements for nitrogen dioxide for regeneration of the filter and aid efficiency.
• the effluent from the reactor 101 containing nitrogenous oxide from the exhaust that was not oxidised in the plasma to nitrogen dioxide and nitric oxide from the reaction of nitrogen dioxide with carbon is then mixed with the hydrocarbon, which can be the fuel used to run the engine, or additional hydrocarbon such as propene (C 3 H 6 ), and the mixture is passed through the second plasma generator 112 in which activated hydrocarbons are produced.
• the term activated hydrocarbons has been defined above.
• the effluent from the reactor 101 can be mixed with a nitrogen containing reductant instead of hydrocarbon although nitrogen containing reductant can be mixed with the exhaust after the latter has passed through the second reactor and before contact with a catalyst .
• Catalyst can also be present in the second plasma region as spheres, pellets, extrudates, fibres, sheets, coils, granules, foams, honeycomb monolith, or as a coating on a foam or honeycomb.
• the non-thermal plasmas produced in the chambers 105 and 110 of the reactor 100 carry out the oxidation of the NO to

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• 1999
  • 1999-01-23 GB GBGB9901413.6A patent/GB9901413D0/en not_active Ceased
• 2000
  • 2000-01-17 JP JP2000594553A patent/JP2002540331A/ja active Pending
  • 2000-01-17 EP EP00900276A patent/EP1149231A2/de not_active Withdrawn
  • 2000-01-17 KR KR1020017009194A patent/KR20010092791A/ko not_active Application Discontinuation
  • 2000-01-17 WO PCT/GB2000/000079 patent/WO2000043102A2/en not_active Application Discontinuation
  • 2000-01-17 AU AU19939/00A patent/AU1993900A/en not_active Abandoned

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