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CN-122003291-A - Catalytic partial wall-flow filter

CN122003291ACN 122003291 ACN122003291 ACN 122003291ACN-122003291-A

Abstract

Catalytic portion wall-flow filters suitable for use in exhaust treatment systems, methods of making catalytic portion wall-flow filters, and methods of using catalytic portion wall-flow filters to treat an engine exhaust stream are disclosed. The filter includes a partial wall-flow filter substrate having an inlet end, an outlet end, and a plurality of porous walls forming channels from the inlet end to the outlet end, wherein some of the channels are plugged channels and some are unplugged flow-through channels. A Selective Catalytic Reduction (SCR) catalyst is coated on the porous walls.

Inventors

  • D. Bunechada
  • F. Foski
  • I. Yahovic
  • J. G. Kosgren
  • D. R. Marvel
  • M. J. VORTON
  • M. Zisman

Assignees

  • 庄信万丰股份有限公司

Dates

Publication Date
20260508
Application Date
20241105
Priority Date
20231106

Claims (15)

  1. 1. A catalytic portion wall-flow filter for use in an exhaust treatment system, the filter comprising: b) A partial wall-flow filter substrate having an inlet end, an outlet end, and a plurality of porous walls forming channels from the inlet end to the outlet end, wherein some of the channels are plugged channels and some are unplugged flow-through channels, and C) A Selective Catalytic Reduction (SCR) catalyst coated on the porous wall.
  2. 2. The catalytic portion wall-flow filter of claim 1, wherein the channels are plugged only adjacent the inlet end.
  3. 3. The catalytic portion wall-flow filter of claim 2, wherein about 50% of the channels are plugged.
  4. 4. The catalytic portion wall-flow filter of claim 1, wherein the channels are plugged only adjacent the outlet end.
  5. 5. The catalytic portion wall-flow filter of claim 4, wherein about 50% of the channels are plugged.
  6. 6. The catalytic portion wall-flow filter of any one of claims 1-5, wherein the hydraulic diameter of the plugged channels is greater than the hydraulic diameter of the unplugged, flow-through channels.
  7. 7. The catalytic portion wall-flow filter of any one of claims 1-5, wherein the hydraulic diameter of the plugged channels is less than the hydraulic diameter of the unplugged, flow-through channels.
  8. 8. The catalytic partial wall-flow filter of any preceding claim, wherein the SCR catalyst comprises vanadium and antimony.
  9. 9. The catalytic portion wall-flow filter of claim 8, wherein the SCR catalyst has a molar ratio of antimony to vanadium of 0.6 to 0.9.
  10. 10. The catalytic portion wall-flow filter of claim 9, wherein the SCR catalyst comprises vanadium, antimony, and cerium.
  11. 11. The catalytic portion wall-flow filter of any preceding claim, wherein the SCR catalyst has a washcoat length of 50% to 90% of a substrate length (L).
  12. 12. The catalytic portion wall-flow filter of any preceding claim, wherein the SCR catalyst has a washcoat length of 60% to 80% of a substrate length (L).
  13. 13. A method for manufacturing a catalytic partial wall-flow filter according to any one of claims 1 to 12, comprising (a) providing a partial wall-flow filter substrate having an inlet end, an outlet end and a plurality of porous walls forming channels from the inlet end to the outlet end, wherein some of the channels are plugged channels and some are unplugged flow-through channels, (b) applying an SCR catalyst washcoat slurry on the porous walls to form a coated wall-flow filter substrate, and (c) calcining the resulting coated wall-flow filter substrate to produce a partial catalytic wall-flow filter.
  14. 14. An exhaust treatment system for treating a combustion exhaust stream, the system comprising a catalytic portion wall-flow filter according to any one of claims 1 to 12.
  15. 15. A method for treating a combustion exhaust stream comprising NOx, the method comprising passing the exhaust stream through a catalytic portion wall-flow filter according to any one of claims 1 to 12, wherein the inlet end is upstream of the outlet end.

Description

Catalytic partial wall-flow filter Technical Field The present invention relates to a catalytic portion wall-flow filter suitable for use in an exhaust gas treatment system, such as an automotive internal combustion exhaust system. The present invention provides an efficient method for remediating engine exhaust flow. Background In automotive applications, there are concerns about the emission of Particulate Matter (PM) from internal combustion engines such as diesel, gasoline or hydrogen engines. The main problem is associated with potential health effects, in particular with very small particles in the nanometer range. Diesel Particulate Filters (DPFs) and Gasoline Particulate Filters (GPFs) have been manufactured using a variety of materials including sintered metal, ceramic or metal fibers, among which the most common types in actual mass production are wall-flow types made of porous ceramic materials manufactured in a monolithic array of many small channels extending along the length of the body. The alternating channels are plugged at one end so that the exhaust gases are forced through the porous ceramic channel walls, which prevent most of the particles from passing through, so that only the filtered gases enter the environment. Ceramic wall-flow filters in commercial production include those made of cordierite, various forms of silicon carbide and aluminum titanate. The actual shape and size of the practical filter on the vehicle and characteristics such as the channel wall thickness and its porosity depend on the application of interest. The average size of the pores in the filter channel walls of the ceramic wall flow filter through which the gas passes is typically in the range 5 μm to 50 μm and is typically about 20 μm. In sharp contrast, most diesel particulate matter from modern passenger car high speed diesel engines is much smaller in size, e.g., 10nm to 200nm. The most widely used DPF is a wall-flow filter. Conventional wall-flow filters include a ceramic honeycomb body having longitudinal, generally parallel cell channels formed by a plurality of intersecting porous walls. The cell channels are typically plugged with ceramic plugging cement to form a checkered pattern of plugs at the end faces of the honeycomb. The cell channels of the filter typically have some ends that are not plugged at the inlet end face of the honeycomb body, referred to herein as "inlet channels". Also, typically, the cell channels also have plugged remaining ends to form a checkered pattern of plugs at the outlet end face of the honeycomb substrate, some of which are unplugged, referred to herein as "outlet channels". The conventional porous wall-flow filter 100, as shown in fig. 1, includes an inlet end 101, an outlet end 102, and a plurality of generally parallel cell channels (inlet cell channels 111 and outlet cell channels 112) separated by porous cell walls 120. The inlet channel includes a plug 130 at the outlet end 102. The outlet channel comprises a plug at the inlet end 101. The plugs 130 are generally located at the ends of the bore passages and typically have a depth of about 5mm to 20 mm. Some PM may remain within the pore structure in the filter wall and this may in some applications build up until the pores are bridged by a network of PM, and this PM network then enables easy formation of a particulate cake on the inner walls of the filter channels. The particulate cake is an excellent filter medium and its presence provides very high filtration efficiency. In some applications, the soot is continuously combusted on the filter as it is deposited, which prevents particulate cake from accumulating on the filter. For some filters, such as light duty diesel particulate filters, it is necessary to periodically remove trapped PM from the filter to prevent the accumulation of excessive back pressure, which is detrimental to engine performance and may result in poor fuel economy. Thus, in diesel applications, the retained PM is removed from the filter by burning it in air during a process during which the amount of available air and the amount of excess fuel used to reach the high temperatures required to ignite the retained PM are very carefully controlled. Removal of the last remaining particulates in the filter, toward the end of this process, commonly referred to as regeneration, can result in a significant reduction in filtration efficiency and release of many small particle bursts into the environment. Thus, the filter may have low filtration efficiency when first used and subsequently used after each regeneration event and also during the latter part of each regeneration process. Accordingly, it is desirable to consistently improve and/or maintain filtration efficiency, such as during the early life of the filter when first used, and/or during and immediately after regeneration, and/or when the filter is loaded with soot. Diesel exhaust systems based on "active" regeneration have become industry stan