Conversion of nitrogen oxides in the presence of a catalyst supported on a mesh-like structure

• US 20030180205A1
• Filed: 03/10/2003
• Published: 09/25/2003
• Est. Priority Date: 10/15/1999
• Status: Active Grant

• Current Assignee: Chuen Y. Yeh, Joakim A. Carlborg, Lawrence L. Murrell, Lothar Schuh, Robert E. Trubac, Rudolf A. Overbeek, Verena R. Schmidt, Yun-Feng Chang
• Original Assignee: Chuen Y. Yeh, Joakim A. Carlborg, Lawrence L. Murrell, Lothar Schuh, Robert E. Trubac, Rudolf A. Overbeek, Verena R. Schmidt, Yun-Feng Chang
• Inventors: Carlborg, Joakim A., Chang, Yun-Feng, Yeh, Chuen Y., Trubac, Robert E., Murrell, Lawrence L., Overbeek, Rudolf A., Schmidt, Verena R., Schuh, Lothar
• Granted Patent: US 6,946,107 B2
• Time in Patent Office: Days
• US Class Current: 423/239.1
• CPC Class Codes: B01D 2257/402 Dinitrogen oxide
• CPC Class Codes: B01D 2257/502 Carbon monoxide
• CPC Class Codes: B01D 2257/702 Hydrocarbons
• CPC Class Codes: B01D 2257/708 Volatile organic compounds V.O.C.'s
• CPC Class Codes: B01D 53/8631 Processes characterised by a specific device
• CPC Class Codes: B01D 53/864 Removing carbon monoxide or hydrocarbons
• CPC Class Codes: B01D 53/8687 Organic components
• CPC Class Codes: B01D 53/885 Devices in general for catalytic purification of waste gases
• CPC Class Codes: B01D 53/9431 Processes characterised by a specific device
• CPC Class Codes: B01D 53/9477 with catalysts positioned on separate bricks, e.g. exhaust systems
• CPC Class Codes: B01J 21/063 Titanium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 21/066 Zirconium or hafnium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 23/22 Vanadium
• CPC Class Codes: B01J 23/30 Tungsten
• CPC Class Codes: B01J 23/42 Platinum
• CPC Class Codes: B01J 35/56 Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
• CPC Class Codes: B01J 35/58 Fabrics or filaments
• CPC Class Codes: B01J 37/0225 of metal substrates
• CPC Class Codes: B01J 37/0228 in several steps
• CPC Class Codes: F01N 13/0097 the purifying devices are arranged in a single housing
• CPC Class Codes: F01N 2330/10 : Fibrous material, e.g. mineral or metallic wool
• CPC Class Codes: F01N 2330/12 : Metallic wire mesh fabric or knitting
• CPC Class Codes: F01N 2330/14 : Sintered material
• CPC Class Codes: F01N 2330/38 : flow channels with means to enhance flow mixing,(e.g. protrusions or projections)
• CPC Class Codes: F01N 3/281 : Metallic honeycomb monoliths made of stacked or rolled sheets, foils or plates
• CPC Class Codes: F01N 3/2814 : all sheets, plates or foils being corrugated
• CPC Class Codes: F01N 3/2821 : the support being provided with means to enhance the mixing process inside the converter, e.g. sheets, plates or foils with protrusions or projections to create turbulence
• CPC Class Codes: F01N 3/2828 : Ceramic multi-channel monoliths, e.g. honeycombs
• CPC Class Codes: F01N 3/2835 : fibrous
• CPC Class Codes: Y02C 20/10 : of nitrous oxide (N2O)
• CPC Class Codes: Y02P 20/151 : Reduction of greenhouse gas [GHG] emissions, e.g. CO2

Abstract

An apparatus for converting at least one nitrogen oxide, such as NO₁O₂, or N₂O converts oxide in the presence of a catalyst supported on a metal mesh-like structure. The mesh-like structure is preferably fibrous formed of metal or ceramic fibers which may include knitted wire, sintered metal fibers and so on and has a porosity greater than about 85%. The mesh is formed into channels, preferably corrugations, and includes vortex generators, which generate turbulence to create a pressure differential across the mesh, to promote flow of fluids through the mesh pores which normally do not exhibit flow therethrough in the absence of such pressure differential. Preferred embodiments of structured packing and monoliths are disclosed each having a catalyst preferably in the mesh pores and/or coated on the fibers for converting the nitrogen oxide. In one embodiment, corrugated mesh-like sheets are arranged in series with a ceramic solid monolith structure with the corrugated sheets initially receiving the fluid with the at least one nitrogen oxide to be converted and which fluid then flows into the monolith structure to complete the conversion. In other embodiments, the mesh-like structure may have different configurations including a honeycomb arrangement and may include metal, metal and ceramic or ceramic and may be fibrous.

Claims

1. A process for removing at least one nitrogen oxide from a fluid, comprising:

forming a mesh structure of a porous material having internal pores and opposing sides, the average pore size of the material being sufficiently small that normally fluid flow is not exhibited through the porous material in the presence of negligible pressure differential thereacross on opposite surfaces, said mesh structure having a porosity of greater than about 85%, the opposing sides forming channels, each channel having a fluid receiving inlet and a fluid outlet, the received fluid for flowing through the channels along the surfaces of the material to and through said outlets from the respective inlets, the pores being in fluid communication with each other and with the channels externally the material at each said side, said material including turbulence generator means one piece therewith for creating a pressure differential across the opposing sides in said flowing fluids, said pressure differential for causing the flowing fluids to flow through the pores transversely through the material from one side to the other side of the material to promote contact between the fluids flowing on the opposite sides of the material and to promote contact with the material in the pores over essentially the entire surface of the material; and

supporting a nitrogen oxide conversion catalyst on the material on the- opposing surfaces and in said pores for reacting with said fluids as the received fluids flow through the channels and through the pores from one side to the opposite side of the material over essentially the entire surface of the material.

2. The process of claim 1 wherein said at least one nitrogen oxide is selected from the group consisting of NO and NO₂ and N₂O.

3. The process of claim 1 wherein the supporting step comprises coating the catalyst onto the mesh structure.

4. The process of claim 3 wherein the coating thickness is less than 30 microns.

5. The process of claim 1 wherein the step of forming the mesh structure includes forming the mesh structure of at least one of a fibrous metal, ceramic-metal or ceramic.

6. The process of claim 1 wherein the step of forming the mesh structure includes forming corrugations in the mesh structure, the corrugations forming said channels, the step of forming the mesh structure including orienting said channels to each other to form said turbulence generator means.

7. The process of claim 1 including the steps of forming the mesh structure into a corrugated structure, forming the corrugated structure into turbulence generator means and then flowing the-fluid through a series arrangement of the corrugated structure and a monolith honeycomb structure.

8. The process of claim 1 comprising:

oxidizing the at least one NO to NO₂ and contacting the NO₂ with a metal carbonate, bicarbonate or hydroxide supported on the mesh structure, said mesh structure comprising one of a metal, ceramic and ceramic/metal and having a porosity of at least 87%.

9. The process of claim 1 wherein said mesh structure has a porosity of greater than 90%.