WO2010141366A2

WO2010141366A2 - Pressure resistant honeycomb reactor

Info

Publication number: WO2010141366A2
Application number: PCT/US2010/036631
Authority: WO
Inventors: James S Sutherland
Original assignee: Corning Incorporated
Priority date: 2009-05-31
Filing date: 2010-05-28
Publication date: 2010-12-09
Also published as: WO2010141366A3; TW201109080A

Abstract

Methods and devices for providing a honeycomb monolith reactors 12 or heat exchangers 12 having improved pressure resistance are disclosed, including the method of (1) providing a honeycomb monolith 20 having a plurality of cells 22, 24 extending in parallel along a common direction, with the cells divided by walls 23, (2) plunge-machining at least a plurality of walls 32 dividing selected adjacent cells 24 of the honeycomb monolith 20 by inserting a plunge machining tool 70 into the honeycomb monolith 20 along a direction 54 lying at an angle to the common direction, such that the machined walls 32 each are breached by an aperture 48 having an edge 50, the edge 50 having a shape, in the direction around the aperture 48, of a smooth curve, and (3) plugging the selected adjacent cells 24 such that at least a portion of the aperture 48 remains open.

Description

PRESSURE RESISTANT HONEYCOMB REACTOR

[0001] This application claims the benefit of priority of U.S. Provisional Application Serial No. 61/182,759 filed on May 31, 2009.

Background

[0002] The present disclosure relates to honeycomb monolith based reactors or heat exchangers, and particularly to such honeycomb monolith based reactors or heat exchangers providing improved pressure resistance, and to methods for forming such devices.

Summary

[0003] According to one embodiment of the present disclosure, a method for providing a honeycomb monolith reactor or heat exchanger having improved pressure resistance is provided, the method comprising (1) providing a honeycomb monolith having a plurality of cells extending in parallel along a common direction, with the cells divided by walls (2) plunge-machining from one or both ends of the honeycomb monolith at least a plurality of walls that divide selected adjacent cells of the honeycomb monolith using a tool with a smoothly tapered end in a manner such that the machined walls each form an obtuse angle with an abutting non-machined wall, and (3) plugging a least some of the selected adjacent cells such that a gap remains between the plug and at least a portion of the machined wall.

[0004] According to another embodiment of the present disclosure, a method for providing a honeycomb monolith reactor or heat exchanger having improved pressure resistance, the method comprising (1) providing a honeycomb monolith having a plurality of cells extending in parallel along a common direction, with the cells divided by walls, (2) plunge-machining at least a plurality of walls dividing selected adjacent cells of the honeycomb monolith by inserting a plunge machining tool into the honeycomb monolith along a direction lying at an angle to the common direction, such that the machined walls each are breached by an aperture having an edge, the edge having a shape, in the direction around the aperture, of a smooth curve, and (3) plugging the selected adjacent cells 24 such that at least a portion of the aperture remains open.

[0005] According to yet another embodiment of the present disclosure, a honeycomb monolith reactor or heat exchanger is provided, the reactor or heat exchanger comprising a honeycomb monolith having a plurality of cells extending in parallel along a common direction, the cells divided by walls. At least a plurality of the walls that divide selected adjacent cells of the honeycomb monolith are lower than walls they abut and form an obtuse angle therewith. Plugging material or plugs close off at least some of the selected adjacent cells from the exterior of the honeycomb monolith such that a gap remains inside the monolith between the inside surface of the plug and at least a portion of an associated lower wall.

[0006] According to still another embodiment of the present disclosure, a honeycomb monolith reactor or heat exchanger is provided, the reactor or heat exchanger comprising a honeycomb monolith having a plurality of cells extending in parallel along a common direction, the cells divided by walls. At least a plurality of the walls dividing selected adjacent cells of the honeycomb monolith are each breached by an aperture having an edge, the edge having a shape, in the direction around the aperture, of a smooth curve. A plugging material or plugs are positioned so as to close off at least some of the selected adjacent cells from the exterior of the honeycomb monolith while leaving at least a portion of a respective associated aperture open.

[0007] Other features and advantages of the present invention will be apparent from the figures and following description and claims. Brief Description of the Figures

[0008] Fig. 1 illustrates a cutaway perspective view of a honeycomb monolith processed according to the prior art;

[0009] Figs. 2 and 3 illustrate a cutaway perspective view of a portion of honeycomb monolith according to, and being processed according to, an embodiment of the present disclosure;

[0010] Fig. 4 illustrates a cutaway perspective view of another portion of a honeycomb monolith according to, and being processed according to, another embodiment of the present disclosure;

[0011] Figs. 5 and 6 illustrate cross-sectional diagrammatic views of yet another portion of a honeycomb monolith according to, and being processed according to, yet another embodiment of the present disclosure;

[0012] Fig. 7 shows a perspective view of a reactor according to and that may be produced according to the methods of the present disclosure;

[0013] Figs. 8 and 9 are cross sections showing alternate internal structure of the reactor of Fig. 7; and

[0014] Figs. 10-12 show plan views of alternate configurations of the reactor of

Fig. 7.

Detailed Description

[0015] Various techniques for fabricating low-cost continuous flow chemical reactors or heat exchangers based on honeycomb monolith technology have been presented by the present inventor and/or his associates, such as those disclosed in

PCT Publication No. WO2008121390, for example, assigned to the present assignee.

[0016] As shown herein in the perspective view of Fig. 7 and in the partial cross section of Fig. 8, in reactors 12 or heat exchangers 12 of the type generally utilized in the context of the present disclosure, a working fluid flows along a path or passage 28 defined within a set of typically millimeter-scale channels 24 in a honeycomb monolith 20, which channels 24 are closed, generally at both ends, by individual plugs or plugging material 26. Selected walls 32 between channels 24 are lowered as seen in the cross-section of Fig. 8 (where every other wall in the cross-section is lowered).

[0017] A gap is left between plugs 26 or continuous plugging material 26 and the top/bottom of the lowered walls 32. This can allow for a long, relatively large volume serpentine fluid passage 28 to be formed in the honeycomb monolith 20 as seen in Fig. 8.

[0018] The passage 28 may be accessed via access ports or holes 30 in the sides of the honeycomb monolith 20. Typically, heat exchange fluid is flowed parallel to the extrusion direction through the many open millimeter-scale channels 22.

[0019] As shown in the cross-section of Fig. 9, If the lowered walls 32 are lowered nearly to the respective far end of the body 20 by means of plunge machining, a high-aspect ratio passage 28 can be produced, which may be accessed by from multiple ports 30. Variations between the two extremes of Figs. 8 and 9 may also be used, such as a serpentine passage that follows more than one cell of the honeycomb monolith at a time, in parallel. Such passages are disclosed in PCT Publication No. WO2008121390, mentioned above.

[0020] Plugs 26 or continuous plugging material 26 can take various forms, including sintered plugs or plugging material 26 typically assuming a shape somewhat like that shown at the bottom of Fig. 9, or other forms, including epoxy or other polymer material and other materials that result in more or less square plugs or plugging material 26 as shown at the top of Figure 9.

[0021] The shape of path or passage 28 in the plane perpendicular to the direction of the cells of the honeycomb monolith 20 may take various forms, as shown in the plan views of Figs. 10-12. As shown in Fig. 10 and as an alternative to a straight line shape as shown in Fig. 7, the passage 28 may have a serpentine shape in the plane perpendicular to the cells of the honeycomb monolith 20. As an additional alternative, a branching shape may be used as shown in Fig. 11, in which the passage 28 divides within the extruded structure 20 into many sub- passages, then re-joins before exiting the structure 20. As another additional alternative, multiple separate paths 28 may be defined through the honeycomb monolith 20 as shown in Fig. 12.

[0022] Sawing with a channel-width sized saw or vertical plunge machining with a straight cutting head are two existing possible means for lowering the walls 23 to form lowered or machined walls 32. As may be seen in the perspective cutaway of a small section of a honeycomb monolith 20 shown in Fig. 1 (prior art), such means have the risk of forming a sharp (acute) or right angle 40 between the machined or lowered wall 32 and an abutting non-machined (non-lowered) wall 52. The sharp or right angle 40 can act as a stress concentration point for internal pressures in the reactor or heat exchanger 12, tending to concentrate those stresses that would tend to separate the machined wall 32 from the abutting non-machined wall 52.

[0023] The present inventor has recognized that, even within the channels of a monolith having millimeter or even sub-millimeter scale channel widths, a honeycomb monolith reactor or heat exchanger 12 formed within such a monolith may be provided with increased pressure resistance by reducing the concentration of stress where a machined wall 32 joins an abutting non-machined wall 52 as shown in Fig. 1. One method for achieving such, shown close-up in the perspective cutaway views of Figs. 2 and 3, and with reference to Figs. 7 and 8, includes providing a honeycomb monolith 20 having a plurality of cells 22, 24 extending in parallel along a common direction, with the cells divided by walls 23, then plunge-machining from one or both ends of the honeycomb monolith 20 using a tool 58 with a smoothly tapered end 60 in a manner such that the machined walls 32 each form an obtuse angle 42 with an abutting non-machined wall 52. Thus the stress concentration produced by the sharp or right angle 40 is reduced.

[0024] For the complete reactor or heat exchanger 12, at least a plurality of the walls 32 that divide selected adjacent cells 24 of the honeycomb monolith 20, desirably all of the walls 32 that divide adjacent pairs of cells 24, are machined in this fashion, some at one end and some at the opposite end of the monolith 20. After this machining, selected adjacent cells 24 are plugged with a plug or plug material 26 such that a gap 44 remains between the plug 26 and at least a portion of the machined wall 32. As seen hi the cutaway perspective view of Fig. 3, the gap 44 can join, adjacent ones of the cells 24 to form a portion of the path or passage 28.

[0025] Desirably, the plunge machining is performed with a tool and in a manner such that the machined walls 32 each have a machined edge 46 having, in the direction along the edge 46, the shape of a smooth curve. This prevents or reduces stress concentration along the edge 46. Desirably, the shape may be circular, elliptical, or parabolic, but other smooth shapes may also be useful.

[0026] The perspective cut-away view of a small portion of a honeycomb monolith 20 as shown in Figs. 4 and 5, with reference also to Figs. 7 and 8, illustrates another method for providing a honeycomb monolith reactor or heat exchanger 12 having improved pressure resistance. As shown in Fig. 4, a honeycomb monolith 20 having a plurality of cells 22, 24 extending in parallel along a common direction, with the cells divided by walls 23, may be plunge- machined by inserting a plunge machining tool 70 into the honeycomb monolith 20 along a direction 54 lying at an angle to the common direction of the honeycomb cells 22, 24. The tool 70 may be a flat-headed plunge cutter or may have a rounded cutting head, as desired. The angle of the direction 54 may be chosen such that the machined walls 32 each are breached by an aperture 48 having an edge 50, with the edge 50 having a shape, in the direction around the aperture 48, of a smooth curve.

[0027] Desirably all but at least a plurality of walls 32 dividing selected adjacent cells 24 of the honeycomb monolith 20 are so machined. The cells 24 are then plugged with plugs 26 or a plugging material 26, such that at least a portion of the aperture 48 remains open.

[0028] Machining such as that depicted in Figure 4 may be performed at both ends of a honeycomb monolith 20 in order to provide openings for a passage 28 like that shown in Fig. 8. As another alternative, plunge machining at an angle may be performed at one end of the honeycomb monolith 20 only, at a relatively shallow angle, as shown in the schematic cross-sectional view of Fig. 5. Such machining may be used to open a high aspect ratio passage 28 like the passage 28 shown in Fig. 9. Desirably, such machining from one end of the monolith 20 is performed such that pairs of remaining portions 56 of the machined walls 32 above and below the respective apertures 48 have roughly the same length, desirably a maximum ratio of lengths in the common direction of 3 : 1 or less, more desirably of 1.5:1 or less. As with other machining methods herein disclosed, at least a plurality of walls 32 dividing selected adjacent cells 24 of the honeycomb monolith 20, desirably all, are thus machined.

[0029] For all methods and devices of the present invention, the honeycomb monolith 20 is desirably, at the start, an extruded green ceramic or glass or glass- ceramic honeycomb monolith 20. Desirably, the monolith 20 is fired only after the relevant selected plunge-machimng as been performed. The plugs may be inserted or formed before or after firing. For maximum thermal and chemical durability, fired plugs are desirable.

[0030] The above-described methods or combinations and variations thereof allow the production of a honeycomb monolith reactor or heat exchanger 12, such as any of those types shown in Figs. 7-12, with improved pressure resistance. The resulting monolith reactor or heat exchanger 12, according to one alternative embodiment of the present disclosure, comprises a honeycomb monolith 20 having a plurality of cells 22, 24 extending in parallel along a common direction, with the cells 22, 24 divided by walls 23 and with at least a plurality of the walls 32 that divide selected adjacent cells 24 of the honeycomb monolith 20 being lower than walls 52 they abut, and forming an obtuse angle 42 therewith.

[0031] The reactor 12 further includes plugging material or plugs 26 closing off at least some of the selected adjacent cells 24 from the exterior of the honeycomb monolith 20 such that a gap 44 remains inside the monolith 20 between the inside surface of the plug 26 and at least a portion of an associated lower wall 32. Desirably, the machined walls 32 of the reactor or heat exchanger 12 each have a machined edge 46 having in the direction along the edge 46 the shape of a smooth curve.

[0032] The monolith reactor or heat exchanger 12 according to another alternative embodiment of the present disclosure comprises a honeycomb monolith 20 having a plurality of cells 22, 24 extending in parallel along a common direction with the cells divided by walls 23, and with at least a plurality of walls 32 of the walls 23 dividing selected adjacent cells 24 of the honeycomb monolith 20 each breached by an aperture 48 having an edge 50, the edge 50 having a shape, in the direction around the aperture 48, of a smooth curve. The reactor further comprises plugging material or plugs 26 positioned so as to close off at least some of the selected adjacent cells 24 from the exterior of the honeycomb monolith 20, while leaving at least a portion of a respective associated aperture 48 open.

[0033] Not as a limiting feature, but as one potential benefits, the methods and devices of the present disclosure can allow greater operating pressures within a honeycomb monolith-based reactor or heat exchanger. This can provide greater productivity for a given chemical process within a given reactor, such as by allowing higher flow rates with corresponding greater throughput.

[0034] Accordingly, the methods and/or devices disclosed herein are generally useful in performing any process that involves mixing, separation, extraction, crystallization, precipitation, or otherwise processing fluids or mixtures of fluids, including multiphase mixtures of fluids — and including fluids or mixtures of fluids including multiphase mixtures of fluids that also contain solids — within a microstructure. The processing may include a physical process, a chemical reaction defined as a process that results in the interconversion of organic, inorganic, or both organic and inorganic species, a biochemical process, or any other form of processing. The following non-limiting list of reactions may be performed with the disclosed methods and/or devices: oxidation; reduction; substitution; elimination; addition; ligand exchange; metal exchange; and ion exchange. More specifically, reactions of any of the following non-limiting list may be performed with the disclosed methods and/or devices: polymerisation; alkylation; dealkylation; nitration; peroxidation; sulfoxidation; epoxidation; amrnoxidation; hydrogenation; dehydrogenation; organometallic reactions; precious metal chemistry/ homogeneous catalyst reactions; carbonylation; thiocarbonylation; alkoxylation; halogenation; dehydrohalogenation; dehalogenation; hydroformylation; carboxylation; decarboxylation; amination; arylation; peptide coupling; aldol condensation; cyclocondensation; dehydrocyclization; esteriflcation; amidation; heterocyclic synthesis; dehydration; alcoholysis; hydrolysis; ammonolysis; etheriflcation; enzymatic synthesis; ketalization; saponification; isomerisation; quaternization; formylation; phase transfer reactions; silylations; nitrile synthesis; phosphorylation; ozonolysis; azide chemistry; metathesis; hydrosilylation; coupling reactions; and enzymatic reactions.

Claims

What is claimed is:

1. A method for providing a honeycomb monolith reactor or heat exchanger 12 having improved pressure resistance, the method comprising: providing a honeycomb monolith 20 having a plurality of cells 22, 24 extending in parallel along a common direction, said cells divided by walls 23; plunge-machining from one or both ends of the honeycomb monolith 20 at least a plurality of walls 32 that divide selected adjacent cells 24 of the honeycomb monolith 20 using a tool 58 with a smoothly tapered end 60 in a manner such that the machined walls 32 each form an obtuse angle 42 with an abutting non-machined wall 52; plugging a least some of the selected adjacent cells 24 such that a gap 44 remains between the plug 26 and at least a portion of the machined wall 32.

2. The method according to claim 1 wherein the step of plunge machining includes machining such that the machined walls 32 each have a machined edge 46 having in the direction along the edge 46 the shape of a smooth curve.

3. The method according to claim 2 wherein the shape is circular.

4. The method according to any of claims 1-3 wherein the step of providing a honeycomb monolith 20 includes providing an extruded green ceramic or glass or glass- ceramic honeycomb monolith 20, and wherein the method further comprises the step of firing the honeycomb monolith 20 after the step of plunge-machining.

5. A method for providing a honeycomb monolith reactor or heat exchanger 12 having improved pressure resistance, the method comprising: providing a honeycomb monolith 20 having a plurality of cells 22, 24 extending in parallel along a common direction, said cells divided by walls 23; plunge-machining at least a plurality of walls 32 dividing selected adjacent cells 24 of the honeycomb monolith 20 by inserting a plunge machining tool 58 into the honeycomb monolith 20 along a direction 54 lying at an angle to the common direction such that the machined walls 32 each are breached by an aperture 48 having an edge 50, the edge 50 having a shape, in the direction around the aperture 48, of a smooth curve; plugging the selected adjacent cells 24 such that at least a portion of the aperture 48 remains open.

6. The method according to claim 5 wherein the step of plunge machining comprises plunge machining performed at two ends of the honeycomb monolith 20.

7. The method according to claim 5 wherein the step of plunge machining comprises plunge machining performed at one end of the honeycomb monolith 20 such that pairs of remaining portions 56, above and below the respective apertures 48 of at least some of the machined walls 32, have a maximum ratio of lengths in the common direction of 3 : 1 or less.

8. The method according to claim 5 wherein the step of plunge machining comprises plunge machining performed at one end of the honeycomb monolith 20 such that pairs of remaining portions 56, above and below the respective apertures 48 of at least some of the machined walls 32, have a maximum ratio of lengths in the common direction of 1.5:1 or less.

9. The method according to any of claims 5-8 wherein the step of providing a honeycomb monolith 20 includes providing an extruded green ceramic or glass or glass- ceramic honeycomb monolith 20, and wherein the method further comprises the step of firing the honeycomb monolith 20 after the step of plunge-machining.

10. The method according to claim 9 wherein the step of firing comprises firing after the step of plugging.

11. A honeycomb monolith reactor or heat exchanger 12 comprising a honeycomb monolith 20 having a plurality of cells 22, 24 extending in parallel along a common direction, said cells 22, 24 divided by walls 23; at least a plurality of walls 32 that divide selected adjacent cells 24 of the honeycomb monolith 20 being lower than walls 52 they abut and forming an obtuse angle 42 therewith; and plugging material or plugs 26 closing off at least some of the selected adjacent cells 24 from the exterior of the honeycomb monolith 20 such that a gap 44 remains inside the monolith 20 between the inside surface of the plug 26 and at least a portion of an associated lower wall 32.

12. The reactor or heat exchanger 12 according to claim 11 wherein the machined walls 32 each have a machined edge 46 having in the direction along the edge 46 the shape of a smooth curve.

13. A honeycomb monolith reactor or heat exchanger 12 comprising: a honeycomb monolith 20 having a plurality of cells 22, 24 extending in parallel along a common direction, said cells divided by walls 23; at least a plurality of walls 32 of the walls 23 dividing selected adjacent cells 24 of the honeycomb monolith 20 each breached by an aperture 48 having an edge 50, the edge 50 having a shape, in the direction around the aperture 48, of a smooth curve; plugging material or plugs 26 positioned so as to close off at least some of the selected adjacent cells 24 from the exterior of the honeycomb monolith 20 while leaving at least a portion of a respective associated aperture 48 open.

14. The honeycomb monolith reactor or heat exchanger 12 according to claim 13 wherein pairs of remaining portions 56 of walls 32 that remain above and below the respective apertures 48 of at least some of the machined walls 32 have a maximum ratio of lengths in the common direction of 3:1 or less and wherein the length of the respective aperture 48 in the common direction is at least twice the length of the shortest respective remaining portion 56.

15. The honeycomb monolith reactor or heat exchanger 12 according to claim 13 wherein pairs of remaining portions 56 of walls 32 that remain above and below the respective apertures 48 of at least some of the machined walls 32 have a maximum ratio of lengths in the common direction of 1.5:1 or less and wherein the length of the respective aperture 48 in the common direction is at least twice the length of the shortest respective remaining portion 56.