WO2001041904A1 - Procede de traitement des gaz d'echappement comprenant so¿x? - Google Patents

Procede de traitement des gaz d'echappement comprenant so¿x? Download PDF

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Publication number
WO2001041904A1
WO2001041904A1 PCT/GB2000/004695 GB0004695W WO0141904A1 WO 2001041904 A1 WO2001041904 A1 WO 2001041904A1 GB 0004695 W GB0004695 W GB 0004695W WO 0141904 A1 WO0141904 A1 WO 0141904A1
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WO
WIPO (PCT)
Prior art keywords
sulfate
absorber
gas
soot
sox
Prior art date
Application number
PCT/GB2000/004695
Other languages
English (en)
Inventor
Martyn Vincent Twigg
Original Assignee
Johnson Matthey Public Limited Company
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 Johnson Matthey Public Limited Company filed Critical Johnson Matthey Public Limited Company
Priority to EP00981474A priority Critical patent/EP1235633A1/fr
Priority to JP2001543242A priority patent/JP2003516491A/ja
Priority to US10/149,505 priority patent/US20030049191A1/en
Publication of WO2001041904A1 publication Critical patent/WO2001041904A1/fr

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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
    • B01D53/92—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
    • B01D53/9445—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC]
    • B01D53/9454—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC] characterised by a specific device
    • 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
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/04—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of alkali metals, alkaline earth metals or magnesium
    • B01J20/041—Oxides or hydroxides
    • 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
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/06—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04
    • 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
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
    • B01J20/16—Alumino-silicates
    • B01J20/18—Synthetic zeolitic molecular sieves
    • 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
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • 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
    • B01D2259/804—UV light
    • 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
    • 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
    • F01N2250/00—Combinations of different methods of purification
    • F01N2250/02—Combinations of different methods of purification filtering and catalytic conversion
    • 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
    • F01N2250/00—Combinations of different methods of purification
    • F01N2250/12—Combinations of different methods of purification absorption or adsorption, and catalytic conversion
    • 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
    • F01N2250/00—Combinations of different methods of purification
    • F01N2250/14—Combinations of different methods of purification absorption or adsorption, and filtering
    • 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
    • F01N2570/00—Exhaust treating apparatus eliminating, absorbing or adsorbing specific elements or compounds
    • F01N2570/04—Sulfur or sulfur oxides
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the present invention provides a process for treating an exhaust gas including sulfur oxides (SOx) and to an exhaust system for carrying out the process.
  • SOx sulfur oxides
  • vehicular exhaust systems typically include a catalytic treatment to control levels of major pollutants emitted by the engine such as unburnt hydrocarbons (HC), CO, soot and nitrogen oxides (NOx).
  • the catalytic converter is designed to assist in converting these pollutants to less harmful species so that the amounts of the major pollutants exiting the exhaust system are within legislatively prescribed levels.
  • SOx One other pollutant found in exhaust gas, SOx, is derived from sulfur in the engine fuel and/or lubricant and is more difficult to treat.
  • SO 2 in exhaust gas can be converted to 'sulfate' over a catalytic converter by oxidation to SO 3 and thence via reaction with water to give sulfuric acid.
  • sulfuric acid potentially damaging to health and the environment, but it forms a mist and is measured as particulate matter (PM) in legislatively prescribed emission test procedures.
  • PM particulate matter
  • Levels of sulfur in fuel and lubricant are set to decrease to meet future emission legislation, but for the meantime the problems it causes in exhaust gas after-treatment remain.
  • SOx can compromise the efficiency of components for controlling exhaust emissions such as Johnson Matthey's Continuously Regenerating Trap CRTTM technology.
  • NO and soot from an internal combustion engine particularly from a diesel engine, by passing it unfiltered over an oxidation catalyst to convert NO to NO , collecting the soot on a filter and combusting the collected soot by reaction with the NO 2 .
  • EP 0582917A1 describes an exhaust system including a NOx trap and an upstream SOx trap.
  • a NOx trap generally includes a component for oxidising NO to NO 2 during lean running conditions e.g. platinum. The NO 2 is subsequently absorbed by a component such as BaO in the NOx trap composition, and is stored as the nitrate. Subsequently, the engine is controlled to run rich, and the stored NO is released (thereby regenerating the NOx trap) and is reduced to N 2 , typically over a catalytic reduction component such as rhodium.
  • EP 0582917A1 includes a SOx trap upstream of the NOx trap of similar formulation to the NOx trap.
  • the invention provides a process for treating an exhaust gas from a lean-burn internal combustion engine containing sulfur oxides (SOx) and at least one other atmospheric pollutant selected from HC, CO, NO and soot, which gas is untreated or has undergone some chemical and/or catalytic treatment, which process comprises the steps of absorbing a sulfate-forming SOx component in a solid absorbent material, passing gas containing SO to atmosphere and periodically replacing the absorbent material.
  • SOx sulfur oxides
  • the absorbent material can be removed from the exhaust system and replaced with fresh absorbent material at intervals.
  • the duration of the interval may depend on, amongst other factors, the capacity of the material for absorbing the sulfate-forming SOx component, and on the level of sulfate-forming SOx component in the exhaust gas flowing in the exhaust system.
  • the capacity remaining in a sulfate trap for absorbing sulfate-forming SOx component can be assessed using standard techniques. These include the use of sensors and/or the programming of an engine management system with pre-determined "maps" to estimate cumulative sulfate-forming SOx component formation in the exhaust system from the use of the engine since the absorbent material was last fresh.
  • the most convenient duration of an interval is that of the service interval, e.g. one year or 12,000 miles on a conventional family vehicle including a light-duty diesel engine. This would enable the absorbent material to be replaced at the same time as other components such as spark plugs and oil filters. Of course, the circumstances may allow that the absorbent material be replaced only at intervals which are multiples of, e.g. two or three times, the regular service interval. It is nevertheless possible that the duration of the interval could extend to the effective lifetime of the vehicle to which the absorbent material is fitted, without it being necessary to replace the absorbent material. Put another way, a vehicle may be scrapped during a period at the end of which the absorbent material will need to be replaced.
  • 'Replacing means removing the absorbent from the exhaust system and inserting a fresh charge thereof.
  • the removed absorbent depending on its composition, can be regenerated off- engine with precautions to avoid impermissible emission of sulfate.
  • the gas to be treated may be raw, i.e. untreated, or may have undergone some chemical and or catalytic treatment prior to the step of absorbing the sulfate-forming SOx component.
  • such preceding treatment comprises oxidising NO to NO 2 .
  • Such a step typically oxidises also HC and CO and possibly some soot components, and may if desired be effected in stages, the first of which oxidises mainly the HC and CO and possibly soot components, and the second oxidises mainly the NO.
  • the step of oxidising NO to NO 2 can also promote oxidation of SO 2 to SO 3 .
  • the catalyst can be chosen and/or the temperature controlled so as to limit SO 2 oxidation, and gas-phase oxidation of SO 2 by NO 2 .
  • the gas may be treated by introduction of ozone, as described in WO 99/36162 or by the action of a plasma generator, as described in WO
  • the skilled person will be aware of a number of ways of reducing the formation of sulfate-forming SOx components in an exhaust system.
  • One way is to keep the temperature of the exhaust gas as low as possible. This can be accomplished by using, for example, exhaust gas recirculation (EGR) to the engine inlet or positioning oxidation catalysts in cooler parts of the exhaust system e.g. underfioor, away from the exhaust manifold.
  • EGR exhaust gas recirculation
  • reducing the level of oxidation of SO 2 is not the sole concern and it usually assumes secondary importance to e.g. hydrocarbon oxidation or oxidation of NO to NO 2 in the CRTTM.
  • HDD vehicles in Europe are defined as vehicles of greater than 3.5 tonnes gross weight. In the majority of US States, HDD is defined as vehicles of greater than 8500 lbs (3856 kg) gross weight. In California, we believe that vehicles of gross weight greater than 6000 lbs (2722 kg) are categorised as non-light duty, with a band for medium-duty diesel from 6000-14000 lbs (2722-6350 kg) gross weight, with heavy-duty diesel above 14000 lbs (6350 kg). For the purposes of this description we intend that the definition "heavy-duty diesel” embrace both medium-duty and heavy-duty diesel as defined under Californian law.
  • SO 3 may be absorbed as such or as a product of further reaction, in particular with water vapour normally present, especially in exhaust gas from an engine consuming hydrocarbon fuel.
  • the gas is treated, e.g. by filtration to remove soot before sulfate removal but after catalytic NO oxidation or ozone introduction or plasma action.
  • Such a process typically uses the above-mentioned CRTTM technology. If the filter is catalysed, with or without a preceding separate NO oxidation, catalytic oxidation of SO 2 on the filter can be limited by choice of catalytic material and/or by control of temperature.
  • the invention provides a system for treating an exhaust gas from a lean-bum internal combustion engine, which process includes an exhaust passage and a sulfate absorber comprising a substrate supporting a solid material for absorbing a sulfate-forming component from SOx in the exhaust gas, which sulfate absorber is adapted to be replaceable.
  • the invention provides a lean-burn internal combustion engine, preferably a diesel engine, most preferably a heavy-duty diesel engine in combination with a system according to the invention.
  • a lean-burn internal combustion engine preferably a diesel engine, most preferably a heavy-duty diesel engine in combination with a system according to the invention.
  • the engine is preferably run on fuel of low sulfur content, for example less than 50, especially less than 10 ppm w/w as sulfur.
  • the invention provides a vehicle including an engine according to the invention.
  • the invention provides a sulfate absorber according to the invention wherein the solid absorbent comprises from 2 to 5 g per cubic inch of a mixed washcoat containing barium oxide (10-20% w/w), ceria (15-40% w/w) and alumina (balance).
  • the invention provides a sulfate absorber according to the invention wherein the solid absorbent comprises from 0.5 to 4.0 g per cubic inch of a 2:1 to 1 :2 mixture of a high-surface area alumina (50-150 m 2 g _1 ) and zeolite beta, the washcoat including calcium oxide at from of 0.1 to 0.5 g per cubic inch (as calcium metal).
  • the absorbent is suitably supported on the surface of a ceramic or metal honeycomb.
  • a conventional washcoat layer may be used.
  • the absorbent may be applied to an uncoated honeycomb. It may be in a vessel adapted to be interchangeably joined to an exhaust treatment reactor or between upstream and downstream sections thereof; or in a cassette adapted to be positioned in such a central section or in the open end of such an upstream or downstream section.
  • the reactor or reactor section may be constructed to removeably accommodate such a cassette or the coated honeycomb.
  • the invention provides a process for regenerating a sulfate-loaded absorber according to the invention comprising removing, preferably by washing, spent absorbent from the surfaces of the substrate and applying fresh absorbent thereto.
  • washing may employ additives such as detergents and measures such as pH adjustment.
  • the washings may be treated to recover spent absorbent components if this is economic.
  • the honeycomb substrate for the absorbers, catalysts and filter for use in the process or system according to the invention may be made structurally of ceramic, for example cordierite, alumina, mullite, silicon carbide, zirconia or sodium/zirconia/phosphate, or metal, for example thermally resistant alloy such as FecraloyTM.
  • the honeycomb has at least 50 cells per square inch (cpsi), possibly more, e.g. up to 800 cpsi if ceramic, or still more e.g. up to 1200 cpsi if metal. Generally the range 100-900 cpsi is preferred.
  • the honeycomb walls are substantially gas-impermeable and preferably carry a surface area-enlarging washcoat suitably comprising one or more of alumina, ceria, zirconia, silicon carbide or other, generally oxidic, material.
  • alumina, ceria, zirconia, silicon carbide or other in and/or on the washcoat, in one or more layers, is the absorbent and/or catalytic material.
  • the gas-impermeability of the walls may be inherent or may be provided by using filter-grade honeycomb and obstructing its pores by wash-coating.
  • the structural material of the filter honeycomb may be selected from the same materials as used for the catalyst honeycomb.
  • the filter honeycomb is ceramic, it may be the product of shaping (e.g. by extrusion) a composition containing sufficient fugitive material to leave on removal e.g. by calcination, the required pores.
  • Honeycomb whether ceramic or metal, may be the product of moulding and sintering a powder, possibly via foam.
  • Other filters may comprise metal mesh or wire.
  • Filter-grade honeycomb suitably has a mean pore diameter in the range 0.1 x 10 " to 20 x 10 " inch (0.25 to 50 ⁇ m).
  • the filter may carry a coating such as the above-mentioned washcoat and/or a catalyst such as one or more PGMs such as Pt+MgO, or La/Cs/V 2 O 5 ⁇ , provided its fluid permeability is not seriously impaired and provided such catalyst is formulated to avoid or limit SO 2 oxidation at accessible temperatures.
  • a coating such as the above-mentioned washcoat and/or a catalyst such as one or more PGMs such as Pt+MgO, or La/Cs/V 2 O 5 ⁇ , provided its fluid permeability is not seriously impaired and provided such catalyst is formulated to avoid or limit SO 2 oxidation at accessible temperatures.
  • the active material comprises for example a platinum group metal (PGM), especially Pt and/or Pd, optionally with other PGMs, e.g. Rh, and other catalytic or promoting components.
  • PGM platinum group metal
  • Rh e.g. Rh
  • a low temperature light- off formulation is generally preferred for the oxidation catalyst.
  • the oxidation catalyst(s) and filter may be provided on a single brick of filter-grade honeycomb, the pores in the catalyst region being obstructed by washcoat.
  • the chemically active coating may comprise for example: (a) compounds of alkali metals, alkaline earth metals, rare earth metals and transition metals, capable of forming sulfates of adequate stability; and (b) adsorptive materials such as zeolites, carbons and high-area oxides.
  • Compounds (a) may be present (before absorption) as composite oxides, e.g. of alkaline earth metal and copper such as Ba-Cu-O or MnO 2 -BaCuO 2 , possibly with added Ce oxide, or Y-Ba-Cu-O and Y-Sr-Co-O, or rare earth mixed oxides such as CeO 2 /ZrO 2 .
  • alkaline earth metal and copper such as Ba-Cu-O or MnO 2 -BaCuO 2 , possibly with added Ce oxide, or Y-Ba-Cu-O and Y-Sr-Co-O, or rare earth mixed oxides such as CeO 2 /ZrO 2 .
  • absorber materials are specified in terms of oxides, it will be appreciated that during operation of the process they may be present as for example hydroxides, carbonates and nitrates appropriate to the gas contacting them.
  • the absorbent is preferably free of material catalytic for
  • the absorbent may be provided in one unit or a succession of separate units.
  • the sulfate absorber may contain materials selected on economic grounds, since it is not regenerated in situ but has a life limited by its chemical absorption capacity.
  • a suitable SOx absorbent comprises at least one alkaline earth oxide, especially calcium oxide, possibly with others such as magnesium oxide e.g. dolomite, or formulations containing SrO or BaO.
  • alkaline earth oxide especially calcium oxide, possibly with others such as magnesium oxide e.g. dolomite, or formulations containing SrO or BaO.
  • Such oxide may adhere direct to the honeycomb or with the aid of a surface- increasing washcoat.
  • it is applied as carbonate, as a mechanically or chemically formed dispersion or by precipitation on to the honeycomb surface.
  • Methods of preparing the sulfate absorber include assembling a washcoat suspension containing sulfate-reactive material, high-surface oxide such as alumina and optionally auxiliary materials such as rare earth oxide, and applying it to the honeycomb.
  • a washcoat suspension containing high-surface oxide such as alumina and/or zeolite is applied to honeycomb and then impregnated with sulfate-reactive material, possibly in solution.
  • one or more components may be applied as a precursor compound convertible e.g. by heating or contacting with hot exhaust gas, to the required active or high-surface material. Examples of such precursors are nitrates, acetates and bicarbonates of alkaline earth metals and hydrated aluminas.
  • the invention is illustrated by the accompanying drawing, which shows in sectional elevation an exhaust gas treatment reactor containing catalysts and absorbers corresponding to the steps of the process of the invention.
  • material items are shown in full lines and the flow of information and control power is shown in dotted lines.
  • the reactor comprises a can having inlet section 10, outlet section 12 and central section 14, the three sections being held together by flanges 16.
  • Inlet 18 is to be connected to the exhaust pipe of an engine cylinder block. Nearest inlet 18 is ceramic honeycomb-supported oxidation catalyst 22.
  • the reactor includes sensors 28, 30, 32 for temperature and gas composition. Sensors 28 and 30 also measure pressure-drop across filter 24. Values sensed by the sensors are reported to and processed by computer 42, to provide control signals, for example, notifying the need to replace sulfate absorber 26. For convenience in replacement, section 14 contains no control gear.
  • exhaust gas first encounters oxidation catalyst 22, which may be in two or more serially connected parts if the oxidation of HC and NO are to be separately optimised. Oxidation of SO 2 to SO 3 by O 2 and NO 2 is limited by choice of catalyst and control of temperature.
  • the gas, containing soot and NO 2 enters filter 24, where the collected soot is combusted by the NO 2 . It now enters reactor central section 14 and is stripped of its sulfate-forming content in absorber 26. It may then be discharged to atmosphere or further treated (not shown).
  • the replaceable trap would also accumulate approximately 80g of sulfate in 20000 miles. Thus a reasonably-sized sulfate absorber for a medium-heavy vehicle would last the service interval.
  • a 12 litre 318 kW turbo-charged, after-cooled direct-injection diesel engine was operated with a series of fuels derived from Swedish class 1 diesel fuel by addition of thiophene to provide three samples each of: no thiophene added fuel and 10, 20, 30 and 40 ppm sulfur w/w fuels.
  • the engine was run on the standard European Steady State (ESC) test cycle and the particulate matter (PM) in the exhaust gas measured in the prescribed way, after the gas had passed through an oxidation catalyst (22) containing platinum on alumina at a platinum loading of 75 g ft "3 (2.65 g litre "1 ) deposited on a ceramic substrate 10.5 inch diameter x 6 inch long (267 x 152 mm) containing 400 cells per square inch (65 cm “2 ) and a cordierite wall flow particulate filter (24) 10.5 inch diameter x 12 inch long (267 x 304 mm) containing 100 cells per square inch (16 cells cm " ).
  • ESC European Steady State
  • a solid absorbent material according to the invention can absorb sulfate-forming SOx components, such as SO 3 , from a gas stream whilst allowing SO 2 to pass.
  • SOx components such as SO 3
  • the sulfate 'trap' was prepared by application of a washcoat of calcium oxide to a loading density of approximately 2.5g in "3 (41. Og cm “3 ) a ceramic honeycomb substrate of 400 cells in "2 (65 cells cm “2 and wall thickness 6 x 10 "3 inch (0.015cm). Cores 1.5 inches (3.8 cm) long were obtained for testing.
  • SO 3 was generated in the gas stream by oxidising the SO 2 using a platinum on alumina catalyst upstream of the core.
  • the synthetic gas mixture entering the oxidation catalyst had the composition CO 2 200ppm, NO 2 200 ppm, SO 2 20 ppm (approximating to about 500 ppm sulfur content diesel fuel), hydrocarbon (C 3 ) 100 ppm, O 2 12%, H 2 O 4.5%, CO 2 4.5%, N 2 balance at a space velocity of 40000 hr "1 for the whole system.
  • Gas exiting the core was analysed using mass spectrometry in real time.
  • a standard oxidation catalyst comprising platinum on alumina coated on a cordierite monolithic substrate (4.66" (11.84 cm) diameter, 3" (7.62 cm) long) having 400 cells/inch 2 (65 cells cm “ ) and wall thickness of 8 1/1000 inch (0.02 cm) with a platinum loading of 1.4 g/litre and a washcoat loading of 150 g/litre, was fitted in an underfloor position on a 1999 model year vehicle with a 1.7 litre naturally aspirated direct injection diesel engine compliant to European Stage 3 emissions regulations. The vehicle was run over the European Stage 3 drive cycle using diesel fuel containing 350 ppm sulfur with typical exhaust gas temperatures experienced in a light duty TransitTM-style van. The measured particulate emissions were 0.146 g/km.
  • the catalyst was then removed and replaced by a bare monolithic substrate having the same dimensions as the previous catalyst, and the vehicle was run under identical conditions over the European Stage 3 test cycle.
  • the particulate emissions were 0.077 g/km showing at least 0.069 g/km of sulfate was produced over the catalyst (the catalyst also removed some hydrocarbon from the particulate emission).
  • a catalyst identical to that used in the first test was prepared with addition of MgO corresponding to 18 g/litre was then fitted to the vehicle, and run over the European stage 3 test cycle, as before.
  • the particulate emissions were 0.056 g/km showing the sulfate absorber removed 0.090 g/km of sulfate.
  • a standard oxidation catalyst comprising platinum on alumina coated on a cordierite monolithic substrate (4.66" (11.84 cm) diameter, 3" (7.62 cm) long) having 400 cells/inch 2 inch (65 cells cm “ ) and wall thickness of 8 1/1000 inch (0.02 cm) with a platinum loading of 2.8 g/litre and a washcoat loading of 150 g/litre, was fitted in an underfloor position on a 1999 model year vehicle with a 1.7 litre naturally aspirated direct injection diesel engine compliant to European Stage 3 emissions regulations.
  • a bare monolithic substrate having the same dimensions as the catalyst was placed behind the catalyst. The vehicle was run over the European Stage 3 drive cycle using diesel fuel containing 350 ppm sulfur with typical exhaust gas temperatures experienced in a light duty TransitTM-style van. The measured particulate emissions were 0.120 g/km.
  • the catalyst was then removed and replaced by a bare monolithic substrate having the same dimensions as the previous catalyst, and the vehicle was run under identical conditions over the European Stage 3 test cycle.
  • the particulate emissions were 0.077 g/km showing at least 0.043 g/km of sulfate was produced over the catalyst (the catalyst also removed some hydrocarbon from the particulate emission).
  • a substrate coated with alumina containing CaO corresponding to 24.5 g/litre was placed behind the platinum on alumina catalyst from the first test, and run over the European Stage 3 test cycle, as before.
  • the particulate emissions were 0.046 g/km showing the sulfate absorber removed 0.074 g/km of sulfate

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Analytical Chemistry (AREA)
  • Combustion & Propulsion (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • General Chemical & Material Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Biomedical Technology (AREA)
  • Health & Medical Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Exhaust Gas After Treatment (AREA)
  • Filtering Of Dispersed Particles In Gases (AREA)
  • Treating Waste Gases (AREA)

Abstract

L'invention concerne un procédé de traitement d'un gaz d'échappement d'un moteur à combustion interne à gaz pauvre contenant des oxydes de soufre (Sox) et au moins un autre polluant atmosphérique choisi parmi HC, CO, NO et des suies, ce gaz ayant été traité ou ayant été soumis à des traitements chimique et/ou catalytique. Ce procédé comprend les étapes consistant à absorber un composant formant du sulfate dans un matériau absorbant solide, à répandre le gaz contenant SO2 dans l'atmosphère et à remplacer de façon périodique le matériau absorbant. Un système permettant de mettre en oeuvre le procédé comprend un passage d'échappement, un absorbant de sulfate (26) comprenant un substrat contenant un matériau solide en vue de l'absorption d'un composé formant du sulfate à partir de SOx dans le gaz d'échappement, cet absorbant de sulfate étant conçu pour être remplacé.
PCT/GB2000/004695 1999-12-11 2000-12-11 Procede de traitement des gaz d'echappement comprenant so¿x? WO2001041904A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP00981474A EP1235633A1 (fr) 1999-12-11 2000-12-11 Procede de traitement des gaz d'echappement comprenant so x?
JP2001543242A JP2003516491A (ja) 1999-12-11 2000-12-11 ＳＯｘを含有する排気ガスの処理方法
US10/149,505 US20030049191A1 (en) 1999-12-11 2000-12-11 Process for treating exhaust gas including sox

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9929252.6 1999-12-11
GBGB9929252.6A GB9929252D0 (en) 1999-12-11 1999-12-11 Engine exhaust treatment

Publications (1)

Publication Number Publication Date
WO2001041904A1 true WO2001041904A1 (fr) 2001-06-14

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PCT/GB2000/004695 WO2001041904A1 (fr) 1999-12-11 2000-12-11 Procede de traitement des gaz d'echappement comprenant so¿x?

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EP (1) EP1235633A1 (fr)
JP (1) JP2003516491A (fr)
GB (1) GB9929252D0 (fr)
WO (1) WO2001041904A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1731727A1 (fr) * 2004-03-24 2006-12-13 Hitachi, Ltd. Dispositif de clarification de gaz d'echappement derive de moteur a combustion interne, procede de clarification de gaz d'echappement, et agent de capture de constituant de soufre pour moteur a combustion interne

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101316992B (zh) * 2005-12-01 2010-06-09 丰田自动车株式会社 内燃机排气净化装置
JP5276487B2 (ja) * 2009-03-18 2013-08-28 日本碍子株式会社 原子力施設から排出されるシリコンオイルの焼却方法
JPWO2012117566A1 (ja) * 2011-02-28 2014-07-07 トヨタ自動車株式会社 内燃機関の排気浄化装置
CN111467947B (zh) * 2020-04-15 2021-01-19 鄂托克旗红缨煤焦化有限责任公司 一种高温工业烟气排放脱硫脱硝处理***

Citations (4)

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Publication number Priority date Publication date Assignee Title
EP0758713A1 (fr) * 1995-08-14 1997-02-19 Toyota Jidosha Kabushiki Kaisha Procédé de purification des gaz d'échappement d'un moteur diesel
EP0814242A1 (fr) * 1996-06-20 1997-12-29 Johnson Matthey Public Limited Company Lutte contre la pollution atmosphérique
EP0815925A1 (fr) * 1996-07-04 1998-01-07 Toyota Jidosha Kabushiki Kaisha Appareil pour purifier les gaz d'échappement d'un moteur Diesel
US5792436A (en) * 1996-05-13 1998-08-11 Engelhard Corporation Method for using a regenerable catalyzed trap

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0758713A1 (fr) * 1995-08-14 1997-02-19 Toyota Jidosha Kabushiki Kaisha Procédé de purification des gaz d'échappement d'un moteur diesel
US5792436A (en) * 1996-05-13 1998-08-11 Engelhard Corporation Method for using a regenerable catalyzed trap
EP0814242A1 (fr) * 1996-06-20 1997-12-29 Johnson Matthey Public Limited Company Lutte contre la pollution atmosphérique
EP0815925A1 (fr) * 1996-07-04 1998-01-07 Toyota Jidosha Kabushiki Kaisha Appareil pour purifier les gaz d'échappement d'un moteur Diesel

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1731727A1 (fr) * 2004-03-24 2006-12-13 Hitachi, Ltd. Dispositif de clarification de gaz d'echappement derive de moteur a combustion interne, procede de clarification de gaz d'echappement, et agent de capture de constituant de soufre pour moteur a combustion interne
EP1731727A4 (fr) * 2004-03-24 2007-07-18 Babcock Hitachi Kk Dispositif de clarification de gaz d'echappement derive de moteur a combustion interne, procede de clarification de gaz d'echappement, et agent de capture de constituant de soufre pour moteur a combustion interne

Also Published As

Publication number Publication date
GB9929252D0 (en) 2000-02-02
EP1235633A1 (fr) 2002-09-04
JP2003516491A (ja) 2003-05-13

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