GB2509115A - Particulate filter soaked in acid - Google Patents

Particulate filter soaked in acid Download PDF

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Publication number
GB2509115A
GB2509115A GB1223124.7A GB201223124A GB2509115A GB 2509115 A GB2509115 A GB 2509115A GB 201223124 A GB201223124 A GB 201223124A GB 2509115 A GB2509115 A GB 2509115A
Authority
GB
United Kingdom
Prior art keywords
filter body
acid
filter
particulate filter
particulate
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.)
Withdrawn
Application number
GB1223124.7A
Other versions
GB2509115A8 (en
GB201223124D0 (en
Inventor
Jeffrey Girbach
Jong Hwan Lee
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.)
Mercedes Benz Group AG
Original Assignee
Daimler AG
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 Daimler AG filed Critical Daimler AG
Priority to GB1223124.7A priority Critical patent/GB2509115A/en
Publication of GB201223124D0 publication Critical patent/GB201223124D0/en
Publication of GB2509115A publication Critical patent/GB2509115A/en
Publication of GB2509115A8 publication Critical patent/GB2509115A8/en
Withdrawn legal-status Critical Current

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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
    • F01N3/022—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 characterised by specially adapted filtering structure, e.g. honeycomb, mesh or fibrous
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/02—Loose filtering material, e.g. loose fibres
    • B01D39/06—Inorganic material, e.g. asbestos fibres, glass beads or fibres
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/04—Additives and treatments of the filtering material
    • B01D2239/0464—Impregnants
    • 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
    • F01N2260/00—Exhaust treating devices having provisions not otherwise provided for
    • F01N2260/10—Exhaust treating devices having provisions not otherwise provided for for avoiding stress caused by expansions or contractions due to temperature variations
    • 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
    • F01N2330/00—Structure of catalyst support or particle filter
    • F01N2330/06—Ceramic, e.g. monoliths
    • 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

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Filtering Materials (AREA)

Abstract

A method for treatment of a particulate filter, in particular for a vehicle exhaust system, in which at least a filter body of the particulate filter is handled, and at least the filter body is soaked in an acid during a predetermined period of time. The filter body may be arranged in a housing prior to soaking in acid. The acid may be an organic acid, for example citric acid diluted in water. The filter body may be soaked for between one and three hours, and preferably for about two hours. An acid solution of a pH below six, and preferably below three, may be used. The acid may have a temperature of between 20ºC and 95ºC, and preferably about 60ºC. After soaking the filter body may be dried at a temperature above 100ºC, and preferably at about 150ºC. The filter body may be ceramic, preferably comprising cordierite and/or aluminium titanate.

Description

Method for treatment of a particulate filter and particulate filter The invention relates to a method for treatment of a particulate filter, in particular for a vehicle, in which at least a filter body of the particulate filter is handled. Furthermore, the invention relates to a particulate filter.
Particulate filters which are used in vehicles, in particular diesel particulate filters, are limited in operation by the ability to survive extreme high temperature evehts. In the course of normal operation a particulate filter collects particulate matter from the exhaust of an engine. This collected particulate matter is burned off in the filter from time to time.
When the quantities of particulate matter which are stored in the particulate filter under many operating conditions are combusted in the filter, heat is released. This heat can crack a filter body of the particulate filter. The ability to survive such thermal events is a key operating parameter of the filter.
The mechanism of failure for a particulate filter is through thermal expansion. During combustion of the collected particulate matter the center of the filter body will become much hotter than the edges, creating a strong thermal gradient from center to edge. This leads to differential expansion from the middle of the filter body to the edge1 which places the center of the filter in compression and the edges in tension. Failure occurs when the amount of growth creates a stress level that is higher than the ultimate strength of the filter body. The amount of growth is related to the magnitude of the temperature gradient and the coefficient of thermal expansion (CTE) of the filter. As a consequence of a considerable amount of growth, the brittle material of the filter body cracks.
Survivability of the particulate filter is improved by designing materials for the filter body that have a low coefficient of thermal expansion or a high strength. Cordierite and aluminium titanate materials which are commonly used for filter bodies of particulate filters achieve acceptable survivability by controlling the coefficient of thermal expansion via the formation of micro cracks in the structure of the filter body. Such micro cracks close as the material expands, taking up the thermal growth of the material and reducing the coefficient of thermal expansion of the filter body as a whole.
It is the object of the present invention to provide a method as well as a particulate filter of the initially mentioned type, by means of which an increased duration of life is achieved.
This object is solved by a method having the features of claim 1 and by a particulate filter having the features of claim 10. Advantageous embodiments with convenient developments of the invention are specified in the dependent claims.
In the method according to the invention at least the filter body is soaked in an acid during a predetermined period of time. It has been found that applying an acid soak process at least to the filter body of the particulate filter significantly reduces the coefficient of thermal expansion of the filter body. This improves the survivability or the duration of life of the particulate filter in extreme thermal events. As the acid soak process dramatically decreases the coefficient of thermal expansion of the filter body, this also considerably reduces the risk of cracking of the filter body in situations with a thermal gradient.
Increased survivability of the particulate filter allows for increased limits of the mass of collected particulate matter in the particulate filter during the utilisation of the particulate filter, in particular in a vehicle. An increased soot mass limit allows less frequent active regeneration of the particulate filter. As fuel is introduced into the exhaust system in order to raise the temperature of the particulate filter during active regeneration, this results in an improved fuel economy. Increasing the survivability of the particulate filter also reduces the warranty efforts and service failures in the field. This leads to reduced costs and down time for customers, and an increase in customer satisfaction.
In an advantageous embodiment of the invention, the filter body is arranged in a housing of the particulate filter prior to the soaking in the acid. In other words the filter body assembled in the housing or canning is soaked in the acid together with the housing.
There is a loss of strength of the filter body due to the soaking process. As the filter body is arranged in the housing, the effect of the soaking on the strength does not affect the handling of the filter body and the ability to arrange the filter body in the housing.
Preferably an organic acid,, in particular diluted in water, is utilized for the soaking process. For example, citric acid has shown good results with respect to a significant decrease in the, coefficient of thermal expansion while the loss of strength is tolerable.
It has proven further advantageous, if at least the filter body is soaked in the acid during one hour to three hours, in particular duilng two hours. An acid solution of a pH below 6, in particular of a pH below 3, can be utilized.
For an efficient treatment of the particulate filter with regard to its survivability, it has been further proven advantageous, if at least the filter body is soaked in the acid with a temperature of about 20 °C to 95 °C, in particular of about 60 t.
In general, the soaking time is dependent on the acid concentration, the pH and the temperature.
In order to facilitate the assembly of the particulate filter, it is further advantageous, if after the soaking process at least the filter body is dried at a temperature above 100 °C, in particular at a temperature of about 150 °G.
The particulate filter according to the invention, which is in particular designed to be arranged in a vehicle, comprises a filter body. At Feast the filter body has undergone soaking in an acid during a predetermined period of time. Such a particulate filter exhibits an improved survivabiUty due to decrease of the coefficient of thermal expansion of the filter body, The preferred embodiments presented with respect to the method for treatment of a particulate filter and the advantages thereof correspondingly apply to the particulate filter according to the invention.
The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figure and/or shown in the figure alone are usable not only in the respectively specified combination, but also in other combinations or alone without departing from the scope of the invention.
Further advantages, features and details of the invention are apparent from the claims, the following description of preferred embodiments as well as based on the drawing.
Therein shows the figure a flow chart illustrating the production of a particulate filter for a vehicle.
The figure illustrates the steps during the production of a ceramic based diesel particulate filter for a vehicle. In a first step 10 a ceramic filter body is arranged in a housing or canning of the particulate filter. The ceramic filter body may comprise cordierite, aluminium titanate, or silicon carbide. This assembly is followed by a soaking process 12, during which the canned filter body is soaked in citric acid with a pH below 3 at a temperature of 66 °C. Other acids, in particular organic acids which are preferably diluted with water can be utilized for this acid treatment.
The canned filter body is soaked in the diluted acid for about two hours. In a next step drying 14 is performed, for example in an oven. During the drying 14 a temperature of about 150°C may be maintained during several hours. After the drying 14 if the particulate filter arrangement 16 of the particulate filter in an exhaust system of a vehicle takes place.
Handling of the filter body during assembly in the housing and handling of the canned filter body can be performed with handling equipment that is known in the art.
A material evaluation of the soaked parts of the particulate filter which has undergone the soaking prOcess 12 in citric acid with a pH below 3 at 66 °C has been performed. Three significant effects on material properties have been found.
The filter lost between 0.3 % to 0.5 % of mass. The modulus of rupture (MOR) decreased from an average of 350 psi (24,13 bar) to an average of 275 psi (18,96 bar). Hence there is a significant loss of strength of the filter body. In order to facilitate the handling of the particulate filter despite of the reduction in the modulus of rupture due to the acid soaking process 12 the filter body is soaked while being arranged in the housing of the particulate filter.
On the other hand the coefficient of thermal expansion (CTE) decreased from an average of 3.5 x io7 per degree Cto 0.4 x per degree C. This reduction of the coefficient of thermal expansion largely offsets the effect of the decrease in the modulus of rupture.
The reduction in the coefficient of thermal expansion significantly improves the survivability of the particulate filter in extreme thermal events. This is due to the fact that with the lower coefficient of thermal expansion the stress level created in the particulate filter due to a rise in temperature during active regeneration of the particulate filter is less important. Therefore the probability that the filter body cracks due to thermal expansion is reduced.
Thermal expansion normally occurs when the particulate matter collected in the particulate filter is burned off during the active regeneration of the particulate filter. In such cases the centre of the filter body becomes much hotter than the edges. This creates a strong thermal gradient from the centre to the edge. With a lower coefficient of thermal expansion this thermal gradient has a lower effect on the differential expansion from the centre of the filter to its edges. As with the acid treatment of the filter body the coefficient of thermal expansion is dramatically decreased the acid soaking process 12 leads to an increased survivability of the particulate filter.

Claims (10)

  1. A fl...;.,....L...-Ar' ffl..t fl7fl4 ma ir'fl I.fl Claims 1. Method for treatment of a particulate filter, in particular for a vehicle, in which at least a filter body of the particulate filter is handled, characterized in that at least the filter body is soaked (12) in an acid during a predetermined period of time.
  2. 2. Method according to claim 1, characterized in that the filter body is arranged (10) in a housing of the particulate filter prior to the soaking (12) in the acid.
  3. 3. Method according to claim 1 or 2, characterized in that an organic acid, in particular diluted in water, is utilized for the soaking process (12).
  4. 4. Method according to any one of claims ito 3, characterized in that at least the filter body is soaked (12) in the acid during one hour to three hours, in particular during about two hours.
  5. 5. Method according to any one of claims ito 4, characterized in that an acid solution of a pH below 6, in particular of a pH below 3, is utilized.
  6. 6, Method according to any one of claims ito 5, characterized in that at least the filter body is soaked (12) in the acid at a temperature of about 20°C to °C, in particular of about 60 °c.
  7. 7. Method according to any one of claims Ito 6, characterized in that after the soaking process (12) at east the filter body is dried (14) at a temperature above 100 °C, in particular at a temperature of about 150 °C.
  8. 8. Method according to any one of claims ito 7, characterized in that after the soaking process (12) of at least the filter body in the acid the particulate filter is arranged (16) in an exhaust system of the vehicle.
  9. 9. Method according to any one of claims ito 8, characterized in that a ceramic filter body, in particular comprising cordierite and/or aluminium titanate, is soaked (12) in the acid.
  10. 10. Particulate filter, in particular for a vehicte, comprising a filter body, characterized in that at least the filter body has undergone soaking (12) in an acid during a predetermined period of time.
GB1223124.7A 2012-12-20 2012-12-20 Particulate filter soaked in acid Withdrawn GB2509115A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB1223124.7A GB2509115A (en) 2012-12-20 2012-12-20 Particulate filter soaked in acid

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1223124.7A GB2509115A (en) 2012-12-20 2012-12-20 Particulate filter soaked in acid

Publications (3)

Publication Number Publication Date
GB201223124D0 GB201223124D0 (en) 2013-02-06
GB2509115A true GB2509115A (en) 2014-06-25
GB2509115A8 GB2509115A8 (en) 2014-08-20

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ID=47682366

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1223124.7A Withdrawn GB2509115A (en) 2012-12-20 2012-12-20 Particulate filter soaked in acid

Country Status (1)

Country Link
GB (1) GB2509115A (en)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1568669A1 (en) * 2002-11-20 2005-08-31 Ngk Insulators, Ltd. Silicon carbide porous body, process for producing the same and honeycomb structure
WO2006080816A1 (en) * 2005-01-27 2006-08-03 End Solutions Inc. Catalyst and system for reducing exhaust of diesel engines
EP1889647A1 (en) * 2005-05-27 2008-02-20 Ibiden Co., Ltd. Honeycomb filter
EP1974792A1 (en) * 2007-03-30 2008-10-01 Ibiden Co., Ltd. Honeycomb filter
EP1997943A1 (en) * 2007-05-25 2008-12-03 Ibiden Co., Ltd. Honeycomb structured body and method for manufacturing the same
WO2011150145A2 (en) * 2010-05-28 2011-12-01 Corning Incorporated Cordierite porous ceramic honeycomb articles

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1568669A1 (en) * 2002-11-20 2005-08-31 Ngk Insulators, Ltd. Silicon carbide porous body, process for producing the same and honeycomb structure
WO2006080816A1 (en) * 2005-01-27 2006-08-03 End Solutions Inc. Catalyst and system for reducing exhaust of diesel engines
EP1889647A1 (en) * 2005-05-27 2008-02-20 Ibiden Co., Ltd. Honeycomb filter
EP1974792A1 (en) * 2007-03-30 2008-10-01 Ibiden Co., Ltd. Honeycomb filter
EP1997943A1 (en) * 2007-05-25 2008-12-03 Ibiden Co., Ltd. Honeycomb structured body and method for manufacturing the same
WO2011150145A2 (en) * 2010-05-28 2011-12-01 Corning Incorporated Cordierite porous ceramic honeycomb articles

Also Published As

Publication number Publication date
GB2509115A8 (en) 2014-08-20
GB201223124D0 (en) 2013-02-06

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