Method for the preparation of a catalysed particulate filter and catalysed particulate filter
Inactive Publication Date: 2015-08-13
HALDOR TOPSOE AS
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- Application Information
AI Technical Summary
Benefits of technology
The present invention relates to a method for preparing a catalysed particulate filter that can simultaneously remove nitrogen oxides and burn off soot. This is achieved by coating the filter with a single wash coat containing two types of catalysts, one for burning off soot and another for selective catalytic reduction of nitrogen oxides. This method is simpler and more cost-effective compared to previous methods that involve segmentary or zone coating of different catalysts. The coated filter has improved heat transfer and a warm-up during a cold start due to the low thermal mass of the combined filter catalyst brick. The synergy between the two catalysts also increases the soot combustion activity and SCR activity compared to a solution with only one of the catalysts.
Problems solved by technology
In particular NOx and particulate matter are material and chemical compounds representing a health and environmental risk and must be reduced or removed from the engine exhaust gas.
Segmentary or zone coating of different catalysts on the filter is, however, an expensive and difficult preparation process.
Method used
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Experimental program
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Effect test
example
[0037]A suspension of the first catalyst is in a first step prepared from a mixture of cerium nitrate and zirconium nitrate followed by a heat treatment to convert the nitrate mixture into the oxides of cerium and zirconium with a molar ratio of Ce / Zr 3:1. In a second step, a suspension of the first catalysts is prepared by mixing 40 g of the cerium oxide zirconium oxide mixture in 80 ml demineralised water. A dispersing agent Zephrym PD-7000 and an antifoam agent are added. The suspension is milled in a bead mill. The particle sizes must be lower than the mean pore diameter of the pores in the wall of the wall flow filter.
[0038]A suspension of the second catalyst is prepared by mixing cerium nitrate and ammonium meta tungstate solutions followed by impregnating the mixed solution on aluminium oxide particles and heat treating the particles at 550° C. for 4 hours in air. Thereby alumina particles with 10% Cerium oxide and 10% tungsten oxide are obtained. 100 g of this tungsten oxide...
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Abstract
A catalysed particulate filter coated with a wash coat on its dispersion side and its permeate side and within partition walls of the filter. The wash coat contains a first catalyst active in burning off soot, together with a second catalyst active in a selective catalytic reduction of nitrogen oxides.
Description
[0001]This is a division of application Ser. No. 13 / 879,664, filed Apr. 16, 2013, which is a 371 of PCT / EP2011 / 005504, filed Nov. 1, 2011, which claims priority to Danish Application No. PA 2010 00991, filed Nov. 2, 2010.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention:[0003]The present invention relates to multifunctional catalysed diesel particulate filters. In particular, the invention relates to a method for the preparation of catalysed diesel particulate filters having both an activity in the removal of nitrogen oxides by the known selective catalytic reduction (SCR) process and an activity in the burning of soot having been captured on the filter.[0004]The invention provides furthermore a catalysed filter with a catalyst being active in the SCR and a catalyst for improved burning of soot.[0005]2. Description of the Related Art:[0006]In addition to unburnt hydrocarbons, diesel exhaust contains, nitrogen oxides (NOx) and particulate matter. In particular NOx and partic...
Claims
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Patent Timeline
Login to View More IPC IPC(8): B01J23/30B01D53/94
CPCB01J23/30B01D53/9418B01D2255/407B01D2255/904B01D2255/65B01D2255/9155B01D53/944B01D53/9463B01D2255/2065B01D2255/20738B01D2255/20761B01D2255/20776B01D2255/50B01J23/10B01J37/0036F01N3/023F01N2510/065B01J37/0215Y02T10/12B01J21/06B01J35/00B01J37/02B01D53/94
Inventor JOHANSEN, KELD
Owner HALDOR TOPSOE AS