REACTOR SYSTEM COMPRISING A CATALYST BED MODULES AND PROCESS FOR SELECTIVE CATALYTIC REDUCTION OF NITROGEN OXIDE CONTAINED IN A GAS STREAM - Patent application

Abstract

The reactor capable of contacting a gas stream with a catalyst composition includes a catalyst bed module having a first group including a first plurality of foam catalyst blocks, each of the first plurality of foam catalyst blocks being bounded by a first front face having a first surface area with an opposing first back face, a first top side having an opposing first bottom side, and a first side face having an opposing first other side, and a second group adjacent to the first group including a second plurality of foam catalyst blocks, each of the second plurality of foam catalyst blocks being bounded by a second front face having a second surface area with an opposing second back face, a second top side having an opposing second bottom side, and a second side face having an opposing second other side, The first back face of the first plurality of foam catalyst blocks and the second back face of the second plurality of foam catalyst blocks are spaced apart and opposed to each other. The reactor also includes a sealing frame disposed between the first and second groups and capable of maintaining the spaced apart relationship and forming a sealed volume between the first and second plurality of foam catalyst blocks, and a support frame having a support surface and an opening and capable of supporting the first and second groups, the first and second groups being secured to the support surface such that the opening is disposed adjacent the sealed volume between the first and second groups, the sealed volume and the opening providing a passageway for gas flow.

Description

[Technical field]

[0001] The present disclosure relates to a system including a lateral flow reactor having catalyst bed modules and a process for the selective catalytic reduction of nitrogen oxides contained in an exhaust gas stream. [Background technology]

[0002] Lateral flow reactor systems are used in many different catalytic applications. Among these is the removal of nitrogen oxide compounds, or de-NOx treatment, of exhaust gas streams from sources such as boilers in thermal power plants and waste incineration plants. The exhaust streams contain concentrations of nitric oxide (NO), nitrogen dioxide NO2, or both (individually or collectively referred to as NOx). NOx can be removed using selective catalytic reduction (SCR), which reduces NOx to diatomic nitrogen (N2) and water by contacting the exhaust gas with a reducing agent (e.g., ammonia) and the catalytic components of the lateral flow reactor system. The catalytic components of the lateral flow reactor system used in SCR processes typically include oxides of either vanadium (V), molybdenum (Mo), or tungsten (W) supported on supports including titania (TiO2).

[0003] WO 2009 / 083593 discloses a reactor used for removing nitrogen oxides (NOx) from a gas stream containing NOx. The reactor includes a lateral flow reactor section. The lateral flow reactor section of the reactor includes a plurality of fixed catalyst beds, each having an upper and lower end and opposing side walls. The upper and lower ends of each fixed catalyst bed are closed with closure plates to prevent gas flow to the upper and lower ends of the fixed catalyst bed. The side walls of each fixed catalyst bed are left partially open and remain permeable to the lateral flow of gas into and through the fixed catalyst bed. The fixed catalyst beds are spaced apart to define spatial passages between each fixed catalyst bed. The closure plates alternately close the upper portions of the spatial passages defined by the spaced apart fixed catalyst beds, thereby providing alternate upper openings to the passages. The closure plates alternately close the bottoms of the passages defined by the spaced fixed catalyst beds not sealed by an upper closure plate, thereby providing alternating bottom openings of the passages.

[0004] The structural arrangement of the lateral flow reactor section provides for directing the flow of gas from top to bottom into a passage with a top opening, across and through the side walls of the fixed catalyst bed, and out of a passage with a bottom opening. It is important to note that the lateral flow reactor section requires that the top and bottom sides of the fixed catalyst bed be sealed by closure plates to prevent gas flow into the fixed catalyst bed at these locations.

[0005] The catalytic component of the fixed bed may be any suitable catalyst that provides catalytic reduction of the nitrogen oxides contained in the gas stream. Among these catalytic compositions, those that include a titania support and a compound of one or more metals selected from vanadium, molybdenum and tungsten are preferred. The catalyst is preferably in the form of a trilobe, a rifled trilobe or a cylinder. However, there is no mention or suggestion of the use of a foam catalyst.

[0006] WO 2017 / 112618 discloses a lateral flow reactor system for removing NOx from a gas stream. The lateral flow reactor system has similar structural features to those of the lateral flow reactor section disclosed in WO 2009 / 083593. However, the fixed catalyst bed used in the lateral flow reactor system of WO 2017 / 112618 includes a ceramic or metal block foam catalyst support instead of a fixed bed of catalyst particles in trilobe, rifled trilobe or cylindrical form. WO 2017 / 112618 discloses a lateral flow reactor section with spaced apart fixed catalyst beds in the form of ceramic or metal foam blocks on which catalytic components are supported. The fixed catalyst beds are closed at both the upper and lower ends. Closure plates prevent the gas stream from bypassing the fixed catalyst beds. The closure plates alternately close the top and bottom passages of the space defined by the spaced apart fixed catalyst beds to direct the lateral flow of gas through the fixed catalyst beds. It is important to note that the lateral flow reactor section requires that the top and bottom sides of the fixed catalyst beds are sealed by closure plates to prevent gas flow into the fixed catalyst beds at these locations.

[0007] US Patent No. 9,504,958 discloses a catalytic filter module for treating gaseous fluids. The module includes block-shaped filter and catalytic elements arranged in spaced relation to one another within a sealed metal frame structure. The catalytic elements include an upstream supply face and a downstream discharge face for discharging treated gas from the module into a discharge channel having an open end for passing filtered and treated gas received from the catalytic elements.

[0008] No. 6,419,889 discloses a highly active and highly selective catalyst useful for the low temperature conversion of nitrogen oxide compounds (NOx) present in a gas stream. The catalyst comprises a high surface area titania support impregnated with a catalytic metal, preferably by contacting the support with a compound of a metal selected from the group consisting of vanadium, molybdenum and tungsten. The catalyst contains 0.5-10 wt.% of the metal. Preferred catalyst compositions are in the form of trilobe, rifled trilobe or cylindrical. A feature of the catalyst that provides its high activity and selectivity is its bimodal pore distribution. However, the configuration of the reactor and catalyst module to be used in combination with the disclosed catalyst is not described.

[0009] JP 2006-212515 A discloses a denitration catalyst for treating exhaust gas containing nitrogen oxides (NOx) using a selective catalytic reduction method in which the exhaust gas is contacted with a reducing agent and a denitration catalyst to reduce NOx to nitrogen and water. The denitration catalyst uses a high surface area foam to support a thin film of titanium oxide and vanadium oxide on the skeletal surface. The denitration catalyst can be formed into various shapes that can be used in various types of equipment. This Japanese publication discloses certain shapes and equipment layouts, including a catalyst layer and a shape that allows the exhaust gas to flow through the catalyst layer, sometimes referred to as a side stream method. Gas inflow prevention plates are arranged above and below the catalyst shape to regulate the flow direction of the exhaust gas.

[0010] There is a continuing desire to develop improved, lower cost catalytic reactor systems for use in the removal of nitrogen oxides from exhaust gas streams. These improved catalytic reactor systems provide high NOx conversion rates at low temperatures and with low pressure drop across the catalytic reactor system. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] International Publication No. 2009 / 083593 [Patent Document 2] International Publication No. 2017 / 112618 [Patent Document 3] U.S. Pat. No. 9,504,958 [Patent Document 4] U.S. Pat. No. 6,419,889 [Patent Document 5] JP 2006-212515 A Summary of the Invention

[0012] Thus, in one embodiment, a reactor capable of contacting a gas stream with a catalyst composition includes a catalyst bed module having a first group including a first plurality of foam catalyst blocks, each of the first plurality of foam catalyst blocks being bounded by a first front face having a first surface area with an opposing first back face, a first top side having an opposing first bottom side, and a first side face having an opposing first other side, and a second group adjacent to the first group and including a second plurality of foam catalyst blocks, each of the second plurality of foam catalyst blocks being bounded by a second front face having a second surface area with an opposing second back face, a second top side having an opposing second bottom side, and a second side face having an opposing second other side. The first back face of the first plurality of foam catalyst blocks and the second back face of the second plurality of foam catalyst blocks are spaced apart and opposed to each other. The reactor also includes a sealing frame disposed between the first and second groups and capable of maintaining the spaced apart relationship and forming a sealed volume between the first and second plurality of foam catalyst blocks, and a support frame having a support surface and an opening and capable of supporting the first and second groups, the first and second groups being secured to the support surface such that the opening is disposed adjacent the sealed volume between the first and second groups, the sealed volume and the opening providing a passageway for gas flow.

[0013] In another embodiment, the catalyst bed module includes a first group having a first plurality of foam catalyst blocks, each of the first plurality of foam catalyst blocks being bounded by a first front face having a first surface area with an opposing first back face, a first top side having an opposing first bottom side, and a first side face having an opposing first other side, and a second group adjacent to the first group having a second plurality of foam catalyst blocks, each of the second plurality of foam catalyst blocks being bounded by a second front face having a second surface area with an opposing second back face, a second top side having an opposing second bottom side, and a second side face having an opposing second other side. The first back face of the first plurality of foam catalyst blocks and the second back face of the second plurality of foam catalyst blocks are spaced apart and opposed to each other. The catalyst bed module also includes a sealing frame disposed between the first and second groups and capable of maintaining a spaced apart relationship to form a sealed volume between the first and second plurality of foam catalyst blocks. The sealing frame includes a transverse element capable of encircling the sealed volume and maintaining a spaced apart relationship, and an extended rim bypass element extending outwardly from and perpendicular to the transverse element for a length. The catalyst bed module further includes a support frame having a support surface and an opening. The support frame is capable of supporting the first and second groups, the first and second groups secured to the support surface such that the opening is disposed adjacent the sealed volume between the first and second groups, the sealed volume and the opening providing a passageway for gas flow.

[0014] In a further embodiment, a process for selective catalytic reduction of nitric oxide compounds contained in a gas stream having a concentration of NO, a concentration of NO2, or a concentration of both compounds includes introducing the gas stream into a reaction zone defined by a vessel. The reaction zone includes a catalyst bed module having a first group having a first plurality of catalyst blocks and a second group having a second plurality of catalyst blocks, and a sealing frame disposed between the first group and the second group, capable of maintaining a spaced apart relationship and forming a sealed volume between the first plurality of foam catalyst blocks and the second plurality of foam catalyst blocks. Each catalyst block of the first and second plurality of catalyst blocks includes a front side with an opposing back side, a top side with an opposing bottom side, and a side with an opposing other side. The top side, side, and other side of the first and second plurality of foam catalyst blocks forming the periphery of the first and second groups are uncoated, and the first and second plurality of catalyst blocks are capable of removing nitric oxide compounds. The process also includes directing the gas stream flow to a front side, a top side, a side, and another side of each of the first and second plurality of foam catalyst blocks forming an outer periphery of the first and second groups, respectively. The sealing frame includes a transverse element capable of surrounding the sealed volume and maintaining a spaced apart relationship, and an extended rim bypass element extending outwardly from and perpendicular to the transverse element for a length, the extended rim bypass element capable of directing the gas stream flow into the sealed volume from the top side, the side, and another side. The process further includes passing the gas stream through the catalyst bed module under deNOx removal reaction conditions, and recovering a treated gas stream having a reduced concentration of NO or NO2, or both, compared to a concentration of NO, NO2, or both compounds. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view of a catalyst bed module according to one embodiment of the present disclosure having a group of pairs of foam catalyst blocks, each pair of the groups being spaced apart from one another by a sealing frame, with the top and side surfaces of the foam catalyst blocks forming part of the periphery of the group being uncovered. [Diagram 2] FIG. 2 is a perspective view of a portion of the lateral flow reactor having the catalyst bed module of FIG. 1, illustrating its components and operation, according to one embodiment of the present disclosure. [Diagram 3] 1 is a plot of total mass gas flow fraction % as a function of residence time (milliseconds (ms)) for model-predicted gas flow through a catalyst bed having a catalyst foam block and a sealing frame without an extended rim bypass element. [Figure 4] 2 is a plot of total mass gas flow fraction % as a function of model-predicted gas flow residence time (in milliseconds (ms)) through the catalyst bed module of FIG. 1. [Diagram 5] FIG. 5 is a perspective cross-sectional view of the lateral flow reactor of FIG. 2 taken along the vertical section line 5-5 shown in FIG. 2, where the sealing frame includes a transverse element and an extended bypass rim element, according to one embodiment of the present disclosure. [Figure 6] FIG. 2 is a side view of the lateral flow reactor having the catalyst bed module of FIG. 1 according to one embodiment of the present disclosure. [Figure 7] FIG. 7 is a bottom plan view of a portion of a lateral flow reactor in the plane and line of sight indicated by section line 7-7 of FIG. 6 according to an embodiment of the present disclosure. [Figure 8] FIG. 8 is a top plan view of a portion of a lateral flow reactor in the plane and viewing direction indicated by section line 8-8 of FIG. 6 according to an embodiment of the present disclosure. [Figure 9] 9 is a cross-sectional side view of a portion of a lateral flow reactor taken along section line 9-9 of FIG. 8 according to one embodiment of the present disclosure. [Figure 10A] FIG. 1 is a detailed top view of a pair of groups having multiple catalyst blocks separated by a sealing frame of a catalyst bed module, with cuts along cutting lines 10B-10B and 10C-10C shown, according to an embodiment of the present disclosure. [Figure 10B] 10B is a cross-sectional view of the pair of groups and sealing frame of FIG. 10A taken along the plane and line of sight indicated by section line 10B-10B of FIG. 10A. [Figure 10C]10C is a cross-sectional view of the pair of groups and sealing frame of FIG. 10A taken along the plane and line of sight indicated by section line 10C-10C of FIG. 10A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Certain existing structural designs of lateral flow reactor (LFR) systems generally require that all sides of the fixed catalyst bed, except the gas inlet and outlet faces, be sealed to direct gas flow laterally through the catalyst bed of the system. For example, if the sides of the fixed catalyst bed are not sealed, NOx-containing gas flowing through the gas inlet face may exit the catalyst bed through the unsealed side rather than the outlet face. Thus, the NOx-containing gas may not contact the catalyst bed for a sufficient time to achieve the desired de-NOx removal. Thus, the top, bottom, and sides of the catalyst bed are sealed or coated, leaving only the front (gas inlet side) and rear (gas outlet side) of the catalyst bed uncoated. That is, the NOx-containing gas bypasses the catalyst bed through the unsealed open side and is not processed for NOx removal. However, the complexity associated with the design and construction of the fully sealed sides makes the existing coated fixed catalyst bed structures costly to manufacture. Thus, it is desirable to have a lower cost and more efficient fixed catalyst bed design that provides the benefits of increased NOx conversion and reduced pressure drop associated with the use of LFR systems compared to existing systems.

[0017] The present disclosure addresses some of the issues regarding construction complexity and cost by providing a simpler structural design for the fixed catalyst bed used in the LFR system. This simpler design eliminates some of the requirements for complex sealing of the different sides of the catalyst bed of the lateral flow reactor, which is necessary to provide a passage for and direct the lateral flow of the gas stream to be processed in the reactor, resulting in the desired residence time of the gas stream in the catalyst bed. The catalyst bed disclosed herein includes a frame support designed such that the sides of the catalyst bed are not completely sealed and the gas stream flowing through the catalyst bed remains in contact with the catalyst bed for a sufficient time to achieve the desired de-NOx removal. Although the fixed catalyst bed disclosed herein does not require sealing of the different sides, the disclosed structural design mitigates the premature spillage of NOx-containing gases that typically occurs when the top, bottom, and sides of the catalyst bed are not sealed or otherwise covered. Remarkably, as described in more detail below, the disclosed fixed catalyst beds having frame supports unexpectedly provide higher NOx conversion rates when used in combination with lateral flow reactors for the deNOx treatment of NOx-containing gas streams. Moreover, the disclosed catalyst beds are easier and less costly to construct than conventional fixed catalyst beds used in LFR systems.

[0018] With the above in mind, FIG. 1 is a perspective view of a fixed catalyst bed module 10 that can be used in an LFR system having frame supports and seals as disclosed herein. In the illustrated embodiment, the catalyst bed module 10 includes a plurality of foam catalyst blocks 12 arranged in groups to form a foam catalyst bed of the LFR system. The catalyst bed module 10 has an axial axis or direction 2, a direction orthogonal to the radial axis or axis 2, and a direction 6 about the circumferential axis or axis 2. The foam catalyst blocks 12 are arranged in a side-by-side stacked relationship and supported by a support frame 14, thereby forming a lattice of foam catalyst blocks 12 referred to as a catalyst bed 25. The support frame 14 may be of unitary construction or may be comprised of separate components (e.g., rods, tubes, etc.) held together by any suitable fasteners (e.g., bolts, screws, clamps, etc.) arranged to contain the foam catalyst blocks 12. The support frame 14 may be removably or permanently coupled to the foam catalyst blocks 12. The catalyst bed module 10 can have any number of foam catalyst blocks 12 in each group. For example, the foam catalyst blocks 12 can be arranged side-by-side, stacked, or side-by-side stacked in numbers of 1, 2, 3, 4, 5, or more. The support frame 14 can be coupled or attached to the front 15 or inlet side of each foam catalyst block 12 by any suitable attachment means. As non-limiting examples, the support frame 14 can be attached or otherwise connected to the catalyst blocks 12 via bolts, clips, adhesives, fasteners, or any other suitable attachment means and combinations thereof.

[0019] Unlike existing LFR systems that use catalyst modules in which the entire sides of the foam catalyst are sealed or covered, the support frame 14 of the present disclosure is designed such that the sides 16 of the catalyst blocks 12 are substantially open (i.e., uncovered, unsealed). For example, as shown in the illustrated embodiment, the sides 16 of the catalyst blocks 12 on the outermost periphery of the catalyst bed module 10 are not sealed or otherwise covered. In certain embodiments, a portion of the support frame 14 may have a lip that wraps around the catalyst blocks 12 located on the outermost periphery of the catalyst bed module 10 such that a portion of the support frame 14 covers a portion of the sides 16, top side 18, and bottom side 19 of the catalyst blocks 12 on the outermost periphery of the catalyst module 10. For example, the support frame 14 may cover 1% to 5% of the sides 16 and a portion of the top side 18.

[0020] As shown in the illustrated embodiment, the catalyst beds 25, 28 are mounted and secured onto the surface 20 of the support 22. The catalyst beds 25, 28 may be secured onto the surface 20 using any suitable attachment means, such as, but not limited to, bolts, clips, adhesives, welding, brazing, or any other suitable attachment means and combinations thereof. In the illustrated embodiment, the catalyst beds 25, 28 are mounted and secured onto the surface 20 such that the catalyst bed modules 10 are perpendicular to the surface 20. However, in other embodiments, the catalyst beds 25, 28 are mounted and secured onto the surface 20 such that the catalyst bed modules 10 are inclined, thereby forming an acute angle between the catalyst bed modules 10 and the surface 20.

[0021] The support 22 includes openings 24 that provide a passageway (or outlet) for a treated gas stream that has been treated through the catalyst bed module 10. For example, as shown in the illustrated embodiment, the catalyst bed module 10 includes a first catalyst bed 25 having catalyst block groups 26a, 26b in spaced apart relationship and a second catalyst bed 28 having catalyst block groups 29a, 29b in spaced apart relationship. As will be appreciated, the catalyst bed module 10 can have any number of catalyst beds, with each catalyst bed having a pair of catalyst block groups in spaced apart relationship. Each catalyst bed 25, 28 is positioned on the support 22 such that an opening 24 is located between each group 26, 29 of the respective catalyst bed 25, 28.

[0022] For ease of explanation of the catalyst beds 25, 28 in FIG. 1, reference will be made only to the catalyst bed 25. As will be understood, the catalyst bed 28 and any other catalyst beds in the catalyst bed module 10 are arranged and function similarly to the catalyst bed 25. As shown in the illustrated embodiment, the groups 26a, 26b are spaced apart and arranged back-to-back such that the back surface 30a or outlet side of each catalyst block 12 in the group 26a faces the back surface 30b of each corresponding catalyst block 12 in the group 26b. Between the two groups 26a, 26b is a gap that aligns with the opening 24 to form a passage between the groups 26a, 26b, as will be described in more detail below with reference to FIG. 2.

[0023] The catalyst bed 25 includes a sealing frame 32 extending along a portion of the outermost periphery of the catalyst bed 25 between the groups 26a, 26b. For example, as shown in the illustrated embodiment, the sealing frame 32 is positioned adjacent the outlet side (e.g., backside 30) of the catalyst bed 25 and abuts the sides 16, tops 18, and bottoms 19 of the catalyst blocks 12 located at the outermost periphery of the groups 26, thereby forming a frame around the outlet sides of the catalyst beds 25, 28. The sealing frame 32 maintains the spaced apart relationship between the groups 26a, 26b by keeping the groups 26a, 26b spaced apart and forming an open space (e.g., gap) therebetween. The sealing frame 32 also hermetically seals the open space to form a sealed volume defined between the three sides of the foam catalyst block 12 and the backside 30 (i.e., outlet side) by the sealing frame 32.

[0024] During operation, the LFR having catalyst bed modules 10 receives a NOx-containing gas stream flowing into one or more inlets 36 of the catalyst bed modules 10, as indicated by arrows 38. The inlets 36 of the catalyst bed modules 10 are disposed between the catalyst beds 25, 28 at the front side 15 of each catalyst block 12 in the respective groups 26, 29. For example, in the illustrated embodiment, the front side 15 of the catalyst blocks 12 of the group 26b of the first catalyst bed 25 faces the front side 15 of the catalyst blocks 12 of the group 29 of the second catalyst bed 28. That is, the catalyst beds 25, 28 are disposed back-to-back and spaced apart on the support 22, thereby forming a space between them that defines the inlet 36.

[0025] The NOx-containing gas stream 38 can enter the inlet 36 from the axial direction 2 (e.g., the top side of the catalyst bed module 10) and the radial direction 4 (e.g., the side of the catalyst bed module 10). While in the inlet 36, the NOx-containing gas stream 38 changes direction relative to the axial direction 2 and the radial direction 4 to enter and flow through the front side 15 (i.e., the inlet side) of the catalyst block 12 in each catalyst bed 25, 28 of the catalyst bed module 10. For example, as shown in the illustrated embodiment, the flow of the NOx-containing gas stream 38 to the front side 15 (or inlet side) of the catalyst block 12 is in a direction 4 substantially perpendicular to the direction 2, thereby flowing laterally through the catalyst bed module 10. After passing through the catalyst block and exiting through the back side 30 (or outlet side) and entering the passage between the groups 26a, 26b, 29a, 29b, the treated gas stream changes flow direction and exits the catalyst bed module 10 in a direction 2 through the opening 24.

[0026] The disclosed system does not provide a completely lateral flow because the catalyst bed module 10 allows at least a portion of the gas flow 38 to flow through the top, bottom and side ends of the catalyst beds 25, 28 instead of the entire gas flow directly entering a single face (i.e., the front 15 or inlet side) of the catalyst block 12. However, an LFR system with the disclosed catalyst bed module 10 provides the advantages of a conventional LFR system even if the gas flow pattern through the LFR system is not completely lateral. Unlike the disclosed catalyst bed module 10, existing catalyst bed modules for LFR systems attempt to seal the top, bottom and side ends of their catalyst beds to prevent gas inflow at those locations and direct the gas flow laterally to a single face of the catalyst bed. In contrast, the disclosed catalyst bed module 10 leaves the ends of the foam catalyst block 12 substantially open and uncovered to allow gas to flow into the foam catalyst block 12 at those locations. This feature of the reactor system disclosed herein unexpectedly improves NOx conversion in deNOx process applications by increasing the residence time of at least a portion of the NOx-containing gas stream 38 within the catalyst module 10. For example, it has been surprisingly found that a portion of the NOx-containing gas stream 38 exits the catalyst bed module 10 through the top side 18 and side 16 of the catalyst block 12 on the periphery of the catalyst module 10, reverses its flow, re-enters the inlet 36, passes laterally through the front face 15, and then exits through the back face 30. Thus, a portion of the NOx-containing gas stream 38 is reprocessed by the re-entering catalyst block 12, thereby increasing the residence time of the NOx-containing gas stream 38 and improving the NOx removal efficiency.

[0027] As mentioned above, certain existing LFR systems use catalyst bed modules with foam catalyst that are sealed or coated on the sides. Such configurations increase the complexity and overall manufacturing costs of the catalyst bed module. However, by using the support frame 14 and sealing frame 32 disclosed herein, the sides 16 of the catalyst blocks 12 on the outermost periphery of the catalyst bed module 10 remain open (e.g., uncoated), thereby allowing the gas flow 38 to enter the catalyst beds 25, 28 through both the top, bottom, and sides.

[0028] The disclosed catalyst bed module 10, when used in a reactor, provides contact between the gas stream 38 and the spaced apart foam catalyst blocks 12, which can provide a substantially lateral flow of the gas stream 38 into and through the foam catalyst blocks 12 in the reactor. The gas stream 38 contacts the catalyst components supported on the foam blocks 12. By the phrase "substantially lateral flow of gas," it is meant that the disclosed reactor system differs from existing conventional lateral flow reactor systems in that the reactor system disclosed herein allows at least a partial flow of the gas stream 38 into and through the unsealed side 16 of the foam catalyst block 12. In contrast, existing lateral flow reactors have catalyst beds or blocks that are hermetically sealed on all sides except the inlet and outlet faces to direct the gas flow laterally through the catalyst bed or block. The reactor system using the disclosed catalyst bed module 10 differs in that it provides for gas flow through the top, bottom, front, and sides of the foam catalyst block 12. As discussed above, it is unexpected that the unique structural design and configuration of the disclosed catalyst module 10 results in improved NOx conversion in deNOx operations.

[0029] The disclosed catalyst module 10 may form part of a reaction zone of an LFR system to provide a low temperature, low pressure drop process for selective catalytic reduction of nitrogen oxide compounds contained in a gas stream having a concentration of either NO or NO2, or both compounds, such as a NOx-containing gas stream 38. For example, an LFR system may include a feed inlet that receives and introduces a NOx-containing gas stream 38 into a reaction zone having the disclosed catalyst bed module 10. The NOx-containing gas stream 38 may come from a number of sources, including power plants, pyrolysis furnaces, incinerators, metallurgical plants, fertilizer plants, and chemical plants. These gas streams may have concentrations of nitrogen oxides, primarily nitric oxide, in the range of 10-10,000 ppm by volume. The NOx-containing gas stream 38 may also contain 1-200 ppm by volume of sulfur oxides (primarily sulfur dioxide), 1-10% by volume of oxygen, 0.5-15% by volume of carbon dioxide, and 5-40% by volume of water vapor. Gas streams from fertilizer plants typically have NO2 concentrations in excess of 50% by volume.

[0030] Upon entering the reaction zone, the NOx-containing gas stream 38 enters the catalyst beds 25, 28 through the front 15, sides 16, 19, and top side 18 and passes through the foam catalyst block 12 of the catalyst module 10 in a substantially lateral gas flow. The NOx-containing gas stream 38 contacts the catalyst components of the foam catalyst block 12 under de-NOxing reaction conditions. A reducing agent is added to the NOx-containing gas stream 38 passing through and contacting the foam catalyst block 12. The preferred reducing agent is ammonia or an ammonia releasing compound. The amount of reducing agent added to the NOx-containing gas stream 38 is preferably such that the molar ratio of reducing agent to NOx is near, and preferably slightly above, the molar ratio required stoichiometrically to minimize the amount of reductant slippage and optimize NOx removal. Suitable de-NOxing reaction conditions include reaction temperatures in the range of 100-480°C, preferably 110-400°C, more preferably 110-350°C, and most preferably 120-250°C. The reaction pressure can be in the range of 0.9 to 20 bar. The gas hourly space velocity can be in the range of 500 to 50,000 Nm 3 / m 3 / time range.

[0031] As mentioned above, the disclosed catalyst bed module 10 includes a plurality of foam catalyst blocks 12 arranged in groups (e.g., groups 26, 29) spaced apart by a sealing frame 32. The sealing frame 32 not only seals or encloses the space between the respective groups 26, 29, but also allows the sides 16, top side 18 and bottom side 19 of each foam catalyst block 12 on the outermost edge of each group 26, 29 to remain substantially uncovered. Additionally, the disclosed sealing frame 32 prevents premature exit of the NOx-containing gas stream 38 through the open sides 16, 18 of the foam catalyst block 12 by forcing the NOx-containing gas stream 38 to penetrate deeper into the foam catalyst block 12 before exiting the catalyst block 12 through the back side 30, as will be described in more detail below. FIG. 2 is an end perspective view of a reactor 50 having the disclosed catalyst bed module 10. Certain features of the reactor 50 are not shown. However, the reactor 50 may be any suitable reactor used to treat and remove NOx or other harmful gases from exhaust gases generated, for example, in power plants, pyrolysis furnaces, incinerators, metallurgical plants, fertilizer plants, and chemical plants, among others. As described above, the catalyst bed module 10 includes a plurality of catalyst beds 25, 28, each having a catalyst group 26, 29 including a plurality of catalyst blocks 12 stacked side by side. The groups 26, 29 are oriented and operably fixed on the support surface 20 in a back-to-back spaced apart relationship with other groups of foam catalyst blocks 12. Each of the groups 26, 29 provides the same function. To facilitate the description of this embodiment, reference will be made only to the catalyst block 12 or the second catalyst bed 28 in the group 29. Each group 29a, 29b includes a plurality of foam catalyst blocks 12a, 12b, respectively. Each catalyst block 12 includes a porous ceramic foam material carrying a catalyst component. The catalyst component preferably comprises an inorganic oxide support and at least one catalytic metal selected from the group consisting of vanadium, molybdenum, tungsten and combinations thereof. A preferred support is titania.

[0032] The porous ceramic foam material has a cellular structure with a ceramic material having a large volume fraction of gas-filled pores. The porous ceramic foam is preferably an open-cell foam, in that the majority of the cells are not completely surrounded by their cell walls, but are open in that the cells are interconnected with other cells to form a network. The porosity of the porous ceramic foam material is very high. For example, the porosity of the foam is such that the void space is greater than 60%. In one embodiment, the void space of the porous ceramic foam material is at least 75%-95%. In particular, the void space of the porous ceramic foam is 80%-90%. The void space is defined as the volume of the structure that is open space divided by the total volume of the structure (openings and ceramic) multiplied by 100.

[0033] The ceramic foam may include any ceramic material that has sufficient strength and is a suitable support for NOx reduction catalysts, such as cordierite, titanium dioxide, alumina, silica, zirconia, or mixtures thereof. The tortuosity of the ceramic foam is preferably greater than 1.0, more preferably greater than 1.5, and most preferably greater than 2.0. The tortuosity may be calculated as the ratio of the flow path length taken by a gas through the ceramic foam divided by the length of the shortest straight path from the inlet to the outlet of the ceramic foam. A straight channel path has a tortuosity of 1.0.

[0034] Ceramic foams as used herein have a pore density of about 5 ppi (pores per inch) to about 50 ppi, preferably about 10 ppi to 40 ppi. More preferably, the ceramic foam has a pore density of 10 ppi to 30 ppi. The number of pores per inch of the foam affects the ability of gas to flow through the foam. The foam cell size will be larger with fewer pores per inch and the foam cell size will be smaller with more pores per inch. A larger cell structure allows for greater gas flow than a smaller cell structure. Fewer pores per inch are most preferred for greater gas flow through the ceramic foam. The number of pores per inch is limited by the structural integrity of the foam.

[0035] Each foam catalyst block 12 is rectangular and bounded by six sides, including a front side 15 with an opposing back side 30, a top side 18 with an opposing bottom side 19, and a side 16a and an opposing side 16b. The foam catalyst blocks 12 in the catalyst module 10 are defined by their width, height, and depth (thickness), respectively. The depth or thickness of the catalyst blocks 12 is relatively small compared to their width and height. Typically, the depth of the catalyst block 12 relative to either the width or height of the catalyst block 12 ranges from 0.05:1 to 0.4:1, preferably 0.08:1 to 0.3:1, and most preferably 0.12:1 to 0.27:1. As should be understood, the foam catalyst block 12 may have any other geometric shape, such as a square, a triangle, a polygon, or any other suitable shape. A plurality of catalyst blocks 12 may be arranged together in rows and columns to form a single layer of catalyst blocks 12 that functions as a single foam catalyst block component that constitutes a group 26. The foam catalyst block component of a group 26 may further include two or more single layers of catalyst blocks 12 stacked together in a parallel orientation to each other. The stacked catalyst blocks 12 may also function as a single foam catalyst block component of a group 26 that constitutes a catalyst module 10. A group 26 may have one, two, three, four, five, or more rows and columns of foam catalyst blocks 12. Group 26a is in a spaced apart relationship to group 26b. Each group 26a, 26b includes a plurality of catalyst blocks 12 arranged in a side-by-side stacked relationship.

[0036] The width, height and depth of the foam catalyst blocks 12 define their boundaries. Thus, each foam catalyst block 12 is bounded by a front surface 15 (i.e., inlet side) having a surface area with an opposing back surface 30 (i.e., outlet side), a top side 18 having an opposing bottom side 19, and a side surface 16a having another opposing side surface 16b. As described above, the catalyst module 10 includes two foam catalyst block groups 26a, 26b, with the back surfaces 30 of the catalyst blocks 12 in each group 26a, 26b facing each other in a spaced apart relationship. The sealing frame 32 maintains the spaced apart relationship between the groups 26a, 26b to form a sealed volume.

[0037] One of the key elements of the catalyst bed module 10 is the sealing frame 32 disposed between each pair of groups 26, 29. For example, referring now to FIG. 2, the sealing frame 32 maintains a spaced apart relationship between the outlet side (i.e., backside 30 side) of each catalyst block 12 of the respective groups 26a, 26b and 29a, 29b to provide an open space 54. The sealing frame 32 not only maintains the catalyst blocks 12 of each pair of groups 26, 29 spaced apart, but also seals the open space 54 to provide a hermetically sealed volume 56 defined by the backside 30 of each catalyst block 12 of the respective group 26, 29 and the sealing frame 32. As used herein, the phrase "hermetic seal" refers to a seal that prevents premature escape of NOx-containing gases from the catalyst blocks and / or the open space. The sealing frame 32 covers three sides of the open space 54 and leaves the openings 24 unsealed / uncovered to allow the treated gas stream (e.g., the gas stream that has undergone deNOx) to exit the sealed volume 56 through the openings 24 in the support 22. As described above, the catalyst block 12 is operably secured to the support surface 20. For example, the openings 24 are operably connected to or incorporated into the support surface 20 to align the openings 24 with the open space 54 to allow the treated gas stream to pass and discharge from the sealed volume 56 to an external destination.

[0038] An advantageous aspect of the disclosed catalyst bed module 10 is that five of the six sides of the catalyst blocks 12 on the periphery of the catalyst bed module 10 are substantially open and uncoated, and thus exposed to gas flow into the foam catalyst blocks 12 at these locations. That is, the front 15, back 30, sides 16, top side 18, and bottom side 19 are open or otherwise uncoated and unsealed. The NOx-containing gas stream 38 enters each foam catalyst block 12 and passes through the depth of the ceramic foam where it contacts the catalyst supported on the ceramic foam. The resulting treated gas leaves the foam catalyst block 12 through each front 15 (i.e., inlet side) and enters the sealed volume 56 between the pair of groups 26, 29.

[0039] Thus, the top side 18 of each respective catalyst block 12a, 12b is substantially open and uncoated to allow the NOx-containing gas stream 38 to flow into the top side 18 of the foam catalyst block 12. This is similar for the side 16a, 16a' and the other side 16b, 16b', the front 15a, 15b and the bottom 19a, 19b. The boundaries of the foam catalyst block 12 at these locations are substantially open and uncoated to allow the flow of gas. That is, the NOx-containing gas stream 38 can flow into the catalyst block 12 at any location along the length and width of the side 16, the front 15 and the top 18. The back 30 or outlet side of the catalyst block 12 is not open to receive the gas flow. As described above, the treated gas 60 exits the catalyst block 12 through the back 30 and is discharged into the sealed volume 56, from where it flows through the sealed volume toward the opening 24.

[0040] This open structure of the catalyst bed module 10 is significantly less costly to manufacture than existing sealed catalyst bed modules. Furthermore, as described herein, the disclosed catalyst bed module 10, along with the use of foam catalyst blocks 12, improves NOx removal when used in combination with a reactor 50 for de-NOx process applications. While open in design, the reactor system utilizing the disclosed catalyst bed module 10 provides for a substantially lateral flow of gases through the reactor.

[0041] One feature that contributes to the improved performance of the catalyst bed module 10 is the structural aspect of the sealing frame 32. As mentioned above, the sealing frame 32 functions by holding each pair of foam catalyst blocks 12 of the groups 26, 29 in a spaced apart relationship, and hermetically seals the open space 54 by forming an airtight seal along the outer edge of the back side 30 (outlet side) of each catalyst block 12. The sealing frame 32 also functions to bypass gases and direct incoming gases at the open sides (e.g., top side 18, sides 16, and front side 15) of the foam catalyst blocks 12 through the foam catalyst block 12 for a distance or length therein. This prevents the incoming NOx-containing gas stream 38 from passing directly into the sealed volume 56, thereby avoiding contact with the catalyst of the ceramic foam block. Thus, the sealing frame 32 also functions by directing the NOx-containing gas stream 38 entering the side 16 of the catalyst block 12 around the periphery of the catalyst beds 25, 28 to travel a distance 62 into the block 12 and into contact with the catalyst components therein for a period of time long enough to cause the necessary reactions.

[0042] The sealing frame 32 may have a grid pattern similar to the support frame 14 and includes a transverse element 64 and an extended rim bypass element 68 or flange. The foam catalyst blocks 12 in each group 26, 29 are sandwiched between the support frame 14 and the sealing frame 32. FIG. 2 shows the sealing frame 32 having a channel-like shape including a transverse element 64 having a width 70 measured end to end and extended rim bypass elements 68 extending orthogonally outward from each end of the transverse element 64 for a length 72 measured from the outer surface of the transverse element 64 to the end of the extended rim bypass element 68. That is, the extended rim bypass elements 68 each extend outward from and orthogonally to both ends of the transverse element 64. In this embodiment, the sealing frame 32 may have a shape similar to that of a structural channel or a C-channel or a parallel flange channel. The channel shape includes a transverse element 64 and two extended rim bypass elements 68 each extending outward from a respective end of the transverse element 64. The extended rim bypass element 68 presses against the outer edge of the respective back surface 30 of the catalyst block 12 on the periphery of the catalyst bed 29. The outer surface of the extended rim bypass element 68 is preferably flat, thereby facilitating an airtight seal when pressed against the outer edge of the portion of the back surface 30 of each foam catalyst block 12 on the periphery of the catalyst bed 28.

[0043] The cross elements 64 provide and support a seal of the space between the two opposing foam catalyst blocks 12 in each group 29 to provide a sealed volume and maintain the spaced apart relationship between the pair of groups 29. Typically, the air-tight seal is provided by a mechanical sealing means for joining in an air-tight manner a mating surface of the extended rim bypass element 68 and an outer edge of the portion of the back surface 30 of each catalyst block 12 on the periphery of the catalyst bed 28. The mechanical sealing means may be selected from any suitable type of mechanical seal, such as a gasket, an adhesive sealant, or any other suitable type of seal.

[0044] The outer edge of the back faces 30 is defined by the surface area of ​​each back face 30 covered by the flat surface of an extended rim bypass element 68 pressed against the back faces 30 of the foam catalyst blocks 12. The extended rim bypass element 68 forms an airtight mechanical seal along the outer edges of the back faces 30 of the catalyst blocks 12a, 12b disposed about the periphery of the catalyst bed 28. The outer edges cover 1-40% of the total surface area of ​​each back face 30 of the respective groups 29a, 29b of the catalyst bed 28.

[0045] 2 is a partial view of a portion of first catalyst bed 25. Group 26 of foam catalyst blocks 12 of first catalyst bed 25 is disposed on support surface 20 in a manner similar to how group 29 of foam catalyst blocks 12 is affixed to support surface 20. Additional group 26 of foam catalyst blocks 12 is in spaced side-by-side stacked relationship with group 29 of foam catalyst blocks 12 to provide open volume 74.

[0046] The open volume 74 is defined by the front side 15 (i.e., inlet side) of the foam catalyst block 12 of the group 26 adjacent to the foam catalyst block 12b of the group 29b, the support surface 20, and the front side 16b of the foam catalyst block 12b of the group 29b. The group 26 of the foam catalyst blocks 12 is also in a spaced-apart side-by-side stacked relationship with respect to the respective group (e.g., group 26b) of the foam catalyst blocks 12 of the catalyst module 10. The open volume 74 is open to receive the flow of the NOx-containing gas stream 38. During operation of the reactor 50, the open volume 74 is filled with the NOx-containing gas stream 38, which flows from the open volume 74 into the front side 15 and bottom side 19 of each foam catalyst block 12 in the groups 26, 29 of the catalyst module 10.

[0047] As shown, in the illustrated embodiment, the NOx-containing gas stream 38 enters five faces or sides (e.g., front side 15, side 16, top side 18, and bottom side 19) of each foam catalyst block 12 in the groups 26, 29 arranged around the periphery of the catalyst bed module 10. The sealing frame 32 blocks direct gas flow into each back side 30 of the foam catalyst block 12 in the respective groups 26, 29 and into the sealed volume 54. Instead, the sealing frame 32 directs the flow of the NOx-containing gas stream 38 through the front side 15, top side 18, bottom side 19, and side 16 of the foam catalyst block 12, such that the NOx-containing gas stream 38 flows substantially laterally through the depth of each foam catalyst block 12 and exits through the back side 30 of each foam catalyst block 12 in the respective groups 26, 29 that are not sealed at the outer periphery by the sealing frame 32.

[0048] A feature of the disclosed catalyst module 10 not found in existing catalyst modules is that the top (top face 18), bottom (bottom side 19) and side (side) ends of the foam catalyst block 12 are not sealed to prevent the inflow of NOx-containing gas flow 38, as is typically found in existing catalyst modules. The top, bottom and both ends are substantially open and uncovered, allowing gas to enter each foam catalyst block 12 through the top, bottom and side ends in addition to the faces 15, 30. As is typical of existing catalyst modules, the front (i.e., inlet side) of the foam catalyst block is substantially open and uncovered to allow gas flow into the foam catalyst block, while the top, bottom and sides are covered or sealed. By covering the top, bottom and sides of the foam catalyst block, gas only enters the front and exits the back. The flow of gas to the front of the foam catalyst block is in the gas flow direction providing a lateral gas flow. Gas enters the foam catalyst block at the front, passes laterally through the depth of the foam catalyst block, and exits the foam catalyst block at the back (i.e., outlet side) into the sealed volume. The resulting treated gas then flows from the sealed volume through the bottom side openings and the support surface openings, then away from the catalyst module and exits the LFR.

[0049] It has been found that, without the disclosed sealing frame 32, allowing the NOx-containing gas 38 to enter the sealed volume between the two groups 26, 28 of catalyst blocks 12 directly through the open top, bottom and side ends of the catalyst blocks 12, the NOx-containing gas 38 does not contact the catalyst sufficiently to provide good NOx conversion. This is because much of the gas entering these locations does not penetrate the catalyst blocks deeply enough to provide sufficient contact time with the catalyst to promote the necessary NOx conversion. What happens is that the gas enters the top, bottom and sides and then directly enters the volume defined by the space between the two catalyst blocks without penetrating any significant depth of the catalyst blocks. For example, FIG. 3 is a plot 75 of total mass flow fraction % versus residence time showing model predicted data for gas flow through a catalyst bed having a foam catalyst block (e.g., foam catalyst block 12) with unsealed / uncoated front, top, bottom and sides and a sealing frame that does not include an extended rim bypass element (e.g., extended rim bypass element 68). As shown in the illustrated plot 75, approximately 15% of the total mass flow has a residence time of 110 milliseconds (ms) or less, indicating partial bypass. In contrast, model predicted data for gas flow through a catalyst bed having a foam catalyst block (e.g., foam catalyst block 12) with an unsealed / uncoated front, top, bottom, and sides and a sealing frame (e.g., sealing frame 32) with an extended rim bypass element (e.g., extended rim bypass element 68) has a residence time of greater than 160 ms, as shown by plot 76 in FIG. 4.

[0050] The disclosed catalyst module 10 structural design solves the problem caused by using open and unsealed top, bottom and side ends of the catalyst blocks by using a sealing frame 32 having a cross element 64 and an extended rim bypass element 68. The sealing frame 32 solves the problem by providing an airtight seal around the outer edge of the back surface 30 (i.e., outlet side) of the foam catalyst blocks 12 located in the outermost portions of the groups 26, 28, preventing the NOx-containing gas 38 from bypassing and prematurely exiting the foam catalyst blocks 12 at the periphery of the catalyst bed module 10.

[0051] The outer edge of the back surface 30 of the catalyst block 12 at the outermost periphery of the catalyst bed 25, 28 is defined by the amount of the surface area of ​​the back surface 30 that is covered and sealed by the extended rim bypass element 64 of the sealing frame 32. The surface area coverage of the outer edge of the back surface 30 of the foam catalyst block 12 is determined and adjusted by setting the length of the extended rim bypass element. The coverage of the outer edge by the extended rim bypass should be at least 1% of the total surface area of ​​the back surface 30 of the foam catalyst block 12, but less than 40% of the total surface area. Preferably, the outer edge covered by the extended rim bypass element ranges from 5% to 30% of the surface area of ​​the foam catalyst block. Most preferably, the covered outer edge ranges from 10% to 20% of the surface area of ​​the foam catalyst block 12.

[0052] The extended rim bypass element 68 functions to allow NOx-containing gas 38 entering and passing directly through the open top side 18, bottom side 19 and side ends 16 of the foam catalyst blocks 12 of the catalyst module 10 to pass through the length of the foam catalyst blocks 12 before bypassing the extended rim bypass element 68 and entering the sealed volume 54 between the foam catalyst blocks 12. This allows the NOx-containing gas 38 to contact the catalyst of the foam catalyst blocks 12 for a sufficient distance and time to allow reactive conversion of the NOx compounds contained in the gas stream. It is unexpected that this configuration results in a higher NOx conversion rate than a catalyst module in which the top, bottom and side ends of the foam catalyst blocks are completely sealed or unsealed without the sealing frame 32 disclosed herein.

[0053] FIG. 5 is a perspective view of a cross section of the reactor 50 shown in FIG. 2. FIG. 5 shows a cut section of the reactor 50 of FIG. 2 along the vertical cut line 5-5. In FIG. 5, the foam catalyst block 12b has been separated and the sealing frame 32 has been cut to expose the structural features within the open space 54 of the sealed volume 56. Additionally, the back surface 30a of the foam catalyst block 12a is shown. The sealing frame 32 includes a cross element 64 (not shown) and an extended rim bypass element 68 that presses against the outer edge of the back surface 30a. As indicated by arrows 60, the treated gas flows out of the back surface 30a into the open space 54, which constitutes the sealed volume 56 formed by the sealing frame 32, the seal formed by the support surface 20, the back surface 30a of the foam catalyst block 12a and the back surface 30b of the foam catalyst block 12b. The treated gas 60 flows from the sealed volume 56 through the openings 24 in the support surface 20.

[0054] FIG. 6 is a side view of an embodiment of an LFR reactor 200 having a plurality of catalyst bed modules 10 according to an embodiment of the present disclosure. The LFR reactor 200 includes four groups 202, 204, 206, 208 of foam catalyst blocks 210 that form a portion of the LFR reactor 200. Each group 202, 204, 206, 208 of foam catalyst blocks 210 is oriented and operatively secured to a support surface 212 in a side-by-side stacked relationship. Also, each group 202, 204, 206, 208 of foam catalyst blocks 210 provides the same function and has substantially the same structure as the other groups of foam catalyst blocks 210. Thus, a description herein of one of the groups 202, 204, 206, 208 of foam catalyst blocks 210 applies equally to each of the other groups of foam catalyst blocks 210. Thus, to facilitate the description of FIG. 6, only group 202 will be referred to.

[0055] The group 202 of foam catalyst blocks 210 includes a first foam catalyst block 214 and a second foam catalyst block 216. Each foam catalyst block 214, 216 is rectangular and bounded by six sides. The foam catalyst blocks 214, 216 are spaced apart and parallel to one another. However, in other embodiments, the foam catalyst blocks 214, 216 may be angled relative to one another rather than parallel.

[0056] The first foam catalyst block 214 includes a first back side 218 (outlet side) having an opposing first front side 220 (inlet side), a first top side 224 having an opposing first bottom side 226, a first side 228 and an opposing first other side (not shown). The second foam catalyst block 216 is disposed in a spaced apart relationship with the first foam catalyst block 214. The second foam catalyst block 216 includes a second back side 234 (outlet side) having an opposing second front side 236 (inlet side), a second top side 238 having an opposing second bottom side 240, a second side 242 and an opposing second other side (not shown).

[0057] 6 shows a first side 228 and a second side 242 facing the viewer, with an opposing first alternative side and a second alternative side shown opposite sides 228, 242 and not visible. Five of the six sides of each foam catalyst block 214, 216 are shown substantially open and uncovered to be exposed to gas flow into the foam catalyst blocks 214, 216 at those locations.

[0058] The sealing frame 246 resides between the first and second foam catalyst blocks 214, 216 and maintains the spaced apart relationship therebetween by keeping the foam catalyst blocks 214, 216 spaced apart. The sealing frame 246 also functions to seal the open space between the foam catalyst blocks 214, 216 to provide an airtight sealed volume 250 defined by the first back surface 218, the second back surface 234, and the sealing frame 246. The sealing frame 246 covers three sides of the open space between the foam catalyst blocks 214, 216, leaving a bottom opening 252 that can provide a passage for gas flow away from the sealed volume 250.

[0059] The first foam catalyst block 214 and the second foam catalyst block 216 are operably secured to a support surface 212 that defines and includes an opening 254. The bottom opening 252 is operably connected to or incorporated into the support surface 212 such that the bottom opening 252 aligns with the opening 254 to provide for the passage of gas flow from the sealed volume 250 to an external destination. The opening 254 is thus configured with the bottom opening 252 to provide the ability to pass gas flow from the sealed volume 250 through the bottom opening 252 and opening 254 to an external destination.

[0060] The sealing frame 246 maintains the spaced apart relationship between the first and second foam catalyst blocks 214, 216. The sealing frame 246 further hermetically seals the open space defined by the two foam catalyst blocks 214, 216 by forming an airtight seal along the outer edges of the first and second back surfaces 218, 234. The sealing frame 246 also directs incoming gas at the open sides of the first and second foam catalyst blocks 214, 216 into the foam catalyst blocks 214, 216 for a distance or length. This prevents the incoming gas from passing directly into the sealed volume 250, thereby avoiding contact with the catalyst of the ceramic foam blocks. The sealing frame 246 provides for directing gas entering the side of the ceramic foam block to travel a distance into the ceramic foam block, so that the gas contacts the catalyst components for a long enough time to cause the required reaction.

[0061] The sealing frame 246 includes a transverse element 258 and an extended rim bypass element 260. The sealing frame 246 has a channel-like shape that includes the transverse element 258 and the extended rim bypass element 260 extending outwardly from each end of the transverse element 258. The extended rim bypass element 260 presses against the outer edges of the first back surface 218 and the second back surface 234.

[0062] The outer edges of the first back surface 218 and the second back surface 234 are defined by the surface area of ​​each back surface 218, 234 that is covered by a flat surface of an extended rim bypass element 260 that presses against the back surfaces 218, 234 of the foam catalyst blocks 214, 216. The extended rim bypass 260 forms a first airtight mechanical seal along the first outer edge of the first back surface 218 and a second airtight mechanical seal along the second outer edge of the second back surface 234. The first outer edge covers 1-40% of the total surface area of ​​the first back surface 218 and the second outer edge covers 1-40% of the total surface area of ​​the second back surface 234.

[0063] Each group 202a of foam catalyst blocks 210 is positioned and affixed in spaced-apart stacked lateral relationship to the support surface 212 in a similar manner to the other groups 202b. Additional groups 204, 206, 208 of foam catalyst blocks 210 are in spaced-apart side-by-side stacked relationship to the groups of foam catalyst blocks 210 to provide an open volume 272.

[0064] The open volume 272 is defined by the second front side 236 of the second foam catalyst block 210, the support surface 212, and the first front side 274 of the foam catalyst block 280 of the adjacent group 204 of foam catalyst blocks 216. The open volume 272 is open to receive a gas flow. During operation of the LFR reactor 200, the open volume 272 fills with gas 282, which flows from the open volume 272 into the second front side 236 and second bottom side 240 of the group 202 of the foam catalyst block 210 and into the second front side 274 and second bottom side 240 of the adjacent group 204 of the foam catalyst block 210.

[0065] The dashed arrows in Figure 6 represent the flow of gas 282 into the foam catalyst blocks 214, 216 of the LFR reactor 200. As shown, gas 282 enters five faces or sides of each foam catalyst block 214, 216 (e.g., front faces 220, 236, 274, bottom side 240, sides 228, 242, opposing sides and top side 224, 238). The sealing frame 246 prevents gas flow (e.g., gas 282) directly into each back face 218, 234 and sealed volume 250 of the foam catalyst block 210. Instead, the sealing frame 246 directs the flow of gas 282 through the front, top, bottom, and sides of the foam catalyst blocks 210, such that the gas 282 flows substantially laterally across the depth of each foam catalyst block 210 and exits as treated gas 284 through the back sides 218, 234 of each foam catalyst block 210 that are not sealed at their outer edges by the sealing frame 246. Although the illustrated embodiment shows only four groups 202, 204, 206, 208, it should be understood that the LFR reactor 200 may have more or less than four groups without departing from the scope of the present disclosure.

[0066] Figure 7 shows a plan view from below of LFR reactor 200, in the plane and line of sight indicated by section line 7-7 in Figure 6. Shown is support surface or plate 212 defining four openings 254 therein, each of which provides an aperture through which gas (e.g., treated gas 284) can pass. Openings 254 are aligned with bottom openings 252 on the opposite side of support surface 212 to provide passage for gas flow from sealed volume 250.

[0067] The first foam catalyst block 214 has a first front surface 220, a first side surface 228, a first other side surface 230, and a first top side 224. The second foam catalyst block 216 is shown having a second front surface 236, a second side surface 242, a second other side surface 244, and a second top side 238. The first back surface 218 and the second back surface 234 of the foam catalyst blocks 214, 218 face each other with a sealing frame 246 maintaining the two in a spaced apart relationship. The respective back surfaces 218, 234 of the two foam catalyst blocks 214, 216 and the sealing frame 246 together define a sealed volume 250.

[0068] During operation of the LFR reactor 200, gas (e.g., gas 282) flows downward, filling the open volume 272 and the volume surrounding the groups 202, 204, 206, 208 of foam catalyst blocks 210. The gas enters the open side of each foam catalyst block 210 and passes laterally through the depth of the foam catalyst block 210 into a sealed volume (e.g., sealed volume 250) from which the gas exits through bottom side opening 252 (hidden) and opening 254 (hidden) to an external destination. The extended rim bypass element 260 of the sealing frame 246 supports the lateral flow of gas through the foam catalyst blocks 210 by directing the gas flow through a desired length of the foam catalyst blocks 210.

[0069] Figure 8 shows a top or plan view of LFR module 200, taken in the plane and viewing direction indicated by section line 8-8 in Figure 7. Shown are four groups of foam catalyst blocks 210 which make up the entire LFR module 200 on a support surface 212. Each group of foam catalyst blocks 210 includes a first foam catalyst block 214 and a second foam catalyst block 216. The top ends of each of the foam catalyst blocks 214 and 216 and the sealing means 246 face the viewer.

[0070] Figure 9 is a cross-sectional side view of a portion of the LFR reactor 200 taken along section line 9-9 of Figure 8. Shown is a cross-sectional view of four groups 202, 204, 206, 208 of foam catalyst blocks 210 of the LFR reactor 200. Each of the groups 202, 204, 206, 208 of foam catalyst blocks 210 are secured to a support surface 212 in a side-by-side stacked relationship.

[0071] The first back surface 218 of the first foam catalyst block 214 and the second back surface 234 of the second foam catalyst block 216 are in opposing spaced apart relationship. The sealing frame 246 maintains the spaced apart relationship and forms an airtight seal along the outer edge of the back surfaces 218, 234 of each foam catalyst block 210 to provide a sealed volume 250. The sealed volume 250 includes an open space defined on three sides by the first back surface 218, the second back surface 234, and the sealing means 246, which together provide a bottom opening 252 that can provide for the passage of gas flow (e.g., treated gas 284) from the sealed volume 250.

[0072] The sealing frame 246 has a channel-like shape including a transverse element 258 and an extended rim bypass element 260 extending outwardly from and perpendicular to each end of the transverse element 258. The extended rim bypass element 260 presses against the outer edges of the first back surface 218 and the second back surface 234 of each foam catalyst block 214, 216.

[0073] The outer edges of the first back surface 218 and the second back surface 234 are defined by the surface area of ​​each respective back surface 218, 234 that is covered by a planar surface of an extended rim bypass element 260 that presses against the back surfaces 218, 234 of the foam catalyst blocks 214, 216, respectively. The extended rim bypass element 260 forms a first gas-tight mechanical seal along the outer edge of the first back surface 218 and a second gas-tight mechanical seal along the outer edge of the second front surface 234. The surface area coverage of the outer edges of the back surfaces 218, 234 of the foam catalyst block 210 is determined and adjusted by setting the length of the extended rim bypass element 260 to provide the necessary outer edge coverage to direct gas flow.

[0074] The sealing frame 246 also directs incoming gas 282 at the open sides of the first and second foam catalyst blocks 214, 216 into and through the foam catalyst blocks 214, 216 a distance or length. This prevents the incoming gas 282 from passing directly into the sealed volume 250, thereby avoiding contact with the catalyst in the ceramic foam blocks 214, 216. The sealing frame 246 also provides for directing gas 282 entering the sides of the ceramic foam blocks 214, 216 to travel a distance into the ceramic foam blocks, so that the gas 282 contacts the catalyst components for a period of time long enough to cause the necessary reaction.

[0075] Thus, the extended rim bypass element 260 functions to allow the gas 282 to flow directly into and through the open top (first top side 224 and second top side 238), bottom (first bottom side 226 and second bottom side 240), and side ends (first side 228, first other side 230, second side 242, and second other side 244 as shown in FIG. 8 ) of each foam catalyst block 214, 216. The extended rim bypass element 260 allows the gas 282 to pass through the length of the foam catalyst block 210 before bypassing the extended rim bypass element 260 and entering the sealed volume 250. This allows the gas 282 to contact the catalyst of the foam catalyst block 210 for a sufficient distance and time to allow reaction of the components contained within the gas stream.

[0076] Fig. 10A provides a detailed view from above of the groups 202, 204, 206, 208 separated by a sealing frame 246. Fig. 10B shows a cross-sectional view of the groups 202, 204, 206, 208 in a plane and line of sight shown by cutting along the section line 10B-10B. Fig. 10C shows a cross-sectional view of the groups 202, 204, 206, 208 in a plane and line of sight shown by cutting along the section line 10C-10C.

[0077] 10A, a top plan view of the groups 202, 204, 206, 208 and the sealing frame 246 is shown. The dashed lines indicate the subsurface transverse element 258 and the extended rim bypass element 260. Also below the top surface of the sealing frame 246 and sandwiched between the first foam catalyst block 214 and the second foam catalyst block 216 is a sealed volume 250. The first back surface 218 of the first foam catalyst block 214 and the second back surface 234 of the second foam catalyst block 216 are in opposing spaced apart relationship and form the sealed volume 250 with the sealing frame 246.

[0078] 10B is a detailed view of section 10B-10B, showing a channel-shaped sealing frame 256 in relation to the first back surface 218 of the first foam catalyst block 214 and the second back surface 234 of the second foam catalyst block 216. Additionally shown are a transverse element 258 and an extended rim bypass element 260 of the sealing frame 256.

[0079] FIG. 10C is a detailed view of section 10C-10C, showing an elevation of group 202 cut vertically in the middle to show the relationship of sealing frame 246 with first back surface 218 of first foam catalyst block 214. Transverse element 258 of sealing frame 246 and extended rim bypass element 260 are shown. Sealing frame 246 abuts and connects to first foam catalyst block 214 along the outer edge of foam catalyst block 14 forming the outermost periphery of group 202, thereby edging foam catalyst block 214. Extended rim bypass element 260 presses against the outer edge of first back surface 218 to provide an airtight seal. Treated gas passes substantially laterally through first foam catalyst block 214 and exits first back surface 218 into sealed volume 250.

[0080] The following examples illustrate the present invention and demonstrate its advantages, but are not intended to limit the scope of the invention.

[0081] Preparation of catalytic foam blocks As mentioned above, the catalyst bed module 10 includes a group 26, 29 of foam catalyst blocks having catalyst components disposed on and / or within the ceramic foam. The ceramic foam can be made by coating a polymer foam structure, such as polyurethane foam, with an aqueous slurry of ceramic materials, such as alumina (Al2O3) and zirconia (ZrO2), followed by drying and firing the impregnated foam to leave only the ceramic material. Calcination is carried out in air at temperatures above 1000°C. Typically, calcination is carried out at temperatures ranging from 1000°C to 2000°C. The slurry contains ceramic particles with diameters ranging from 0.1 μm to 10 μm and water, along with appropriate amounts of wetting agents, dispersion stabilizers, and viscosity modifiers. Calcination evaporates or burns off the polymer, leaving behind a sintered ceramic.

[0082] After calcination and sintering, the remaining ceramic foam has an interconnected internal tortuous pore structure, also called a reticulated structure. This structure provides turbulent flow of gas through the foam, compared to other types of supports such as honeycomb channels, improving gas contact with any catalyst supported by the ceramic foam. The catalytic components are desirably applied to the ceramic foam as a washcoat of a slurry of particles of titania support and catalytic metal. The most preferred catalysts for application to the ceramic foam are those described in U.S. Pat. No. 6,419,889, which is incorporated herein by reference.

[0083] The titania support of the catalyst component can be made by mixing titania powder with water and a peptizer to form an extrudable paste. The extrudable paste is extruded into extrudates of any suitable shape, such as cylindrical and trilobal, dried, and then calcined at a temperature below 650°C, preferably between 350°C and 600°C. The extrudates are then contacted with one or more metal compounds of metals selected from the group consisting of vanadium, molybdenum, and tungsten. The extrudates are preferably impregnated with an aqueous solution of the metal compounds. After the metals are incorporated into the titania support, it is dried and then calcined at a calcination temperature in the range of 350-550°C for a calcination time in the range of 0.5-6 hours. The titania supported catalyst has a surface area of ​​about 50 m2 as measured by nitrogen adsorption. 2 / g~about 150m 2 The catalyst may have a bimodal pore distribution with greater than 90% of the pore volume residing in pores having a diameter up to about 100 nm, where pore volume is considered to be the pore volume residing in pores having a diameter from about 1 nm to about 100 nm.

[0084] As discussed above, the foam catalyst block 12 includes a catalytic component incorporated on or into the ceramic foam by any suitable impregnation or washcoating method. When the reactor system is used in a deNOx application, the catalytic component preferably includes titania impregnated with a metal selected from the group consisting of vanadium, molybdenum, tungsten, and combinations thereof.

[0085] The titania supported catalyst described above can be used to make a slurry that is applied to a ceramic foam as a washcoat. The supported catalyst is crushed or milled to form particles having diameters ranging from 0.1 μm to 10 μm. The powder is mixed with water and appropriate amounts of wetting agents, dispersion stabilizers, and viscosity modifiers to obtain a slurry that is applied to the ceramic foam as a washcoat. The washed coated ceramic foam is then further dried and calcined to produce a foam catalyst block that is used as a component of the lateral flow reactor module of a reactor system. EXAMPLES

[0086] This example describes an experimentally designed foam catalytic reactor module representative of a comparative fully sealed side-flow deNOx reactor (comparative reactor) and an open side-flow deNOx reactor according to an embodiment of the present disclosure (inventive reactor). The foam catalytic reactor modules were tested for their deNOx performance. A summary of the comparative results from this testing is presented, which shows the improvement in deNOx conversion provided by the open-side reactor design over the fully sealed reactor design.

[0087] The comparative reactor contained a square foam catalyst block having dimensions of 300 mm (W) x 300 mm (L) x 100 mm (H). The comparative reactor was completely sealed on four sides (e.g., top, bottom, and both sides) and configured such that the gaseous feed entered the front of the foam catalyst block and passed through the depth of the foam catalyst block. Treated gas passed out of the foam catalyst block through the back side opposite the front side.

[0088] The components of each foam catalyst block of the foam catalyst reactor module were porous ceramic foam blocks washcoated with a slurry of vanadium impregnated titania particles or powder. The vanadium impregnated titania catalyst was prepared according to the method disclosed in U.S. Pat. No. 6,419,889 and milled into a powder that was used to prepare an aqueous slurry for application as a washcoat. The vanadium impregnated titania contained vanadium in an amount of about 3.2% by weight of the impregnated titania. The foam catalyst blocks contained about 50% by weight of vanadium impregnated titania after drying of the washcoated porous ceramic foam.

[0089] The reactor according to one embodiment of the present disclosure was of the same design as the comparative reactor, except that one of the four sides of the square foam catalyst block was open to the gas feed. This allowed the gaseous feed to pass through the side of the foam catalyst block and the front of the catalyst block. To simulate an industrial-scale reactor with catalyst bed modules as disclosed herein (e.g., the front and top, bottom, and sides are open and unsealed), the catalyst bed modules used in the bench-scale test reactor had a total surface area (SA) of the front of the catalyst bed module. F1 ) to the open side (SA S1 ) total surface area ratio (SA S1 :SA F1 ) is the total frontal surface area (SA) of an industrial-scale reactor having the catalyst bed module of the present disclosure. F2 ) to the total open surface area (SA S2 ) ratio (SA S2 :SA F2 ) was required to be approximately equal to the SA ratio. S1 :SA F1 =SA S2 :SA F2 This was accomplished by leaving open and unsealed one of the four sides and the front of the catalyst bed module in the bench-scale test reactor. For example, for an industrial-scale reactor having a catalyst bed module with a pair of foam catalyst block groups, each group has a total dimension of 1392 x 100 millimeters (mm), four open sides (e.g., top, bottom, and both sides), and an open front, with the total surface area of ​​the four open sides being approximately 5600 cm. 2 The total front surface area is 19,600 cm 2 As a result, SA S2 :SA F2 The ratio is 0.286. SA of catalyst bed module in industrial scale reactor S2 :SA F2 To match the ratio, the bench-scale test reactor was required to have a foam catalyst block with dimensions of 300 x 300 x 10 mm with one open side and an open front, with the total surface area of ​​the single open side being approximately 300 cm. 2 The total front surface area is 900 cm2 and as a result, SA S1 :SA F1 The ratio is 0.333, which corresponds to the SA of the catalyst bed module of the industrial-scale reactor. S2 :SA F2 The ratio is essentially equal to 0.286.

[0090] A natural gas burner was used to test the de-NOx performance of the two reactor modules. The gas had a NOx concentration of 200 ppm and was burned for 18,000 hours. -1 The feed gas to the DeNOx reactor was injected with 19% aqueous ammonia at a rate that provided a space velocity of 100 ppm. The NOx conversion performance of each reactor was tested at five different inlet temperatures: 140°C, 160°C, 180°C, 200°C, and 220°C.

[0091] The results of the performance tests of the DeNOx reactor are summarized in Table 1 below.

[0092] [Table 1]

[0093] The data presented in Table 1 shows that the open-side foam catalytic reactor module provides higher NOx conversion than the comparative fully sealed foam catalytic reactor module at all inlet reactor temperature conditions. This result is unexpected because it was believed that passing the entire feed gas flow through the entire depth of the foam catalyst block would provide better contact between the feed gas and the foam catalyst block, and therefore better reaction. Instead, allowing at least a portion of the feed gas flow to pass through the side of the foam catalyst block provides better NOx conversion. Note that the difference in NOx conversion decreases as the inlet temperature increases. However, even at higher reactor inlet temperatures, the open-side foam catalytic reactor module still provides higher NOx conversion than the fully sealed foam catalytic reactor module. At lower inlet reactor temperatures, the difference in NOx conversion increases significantly. These data demonstrate that by directing the feed gas into the side of the reactor foam catalyst block, NOx conversion is improved compared to directing the entire feed gas flow into the front of the DeNOx reactor foam catalyst block.

Claims

1. A reactor configured to contact a gas stream with a catalyst composition, comprising:

1. A catalyst bed module comprising: a first group including a first plurality of foam catalyst blocks, each of the first plurality of foam catalyst blocks being bounded by a first front side having a first surface area with an opposing first back side, a first top side having an opposing first bottom side, and a first side having an opposing first other side; a second group adjacent to the first group and including a second plurality of foam catalyst blocks, each of the second plurality of foam catalyst blocks being bounded by a second front side having a second surface area with an opposing second back side, a second top side having an opposing second bottom side, and a second side having an opposing second other side, the first back side of the first plurality of foam catalyst blocks and the second back side of the second plurality of foam catalyst blocks opposing each other in a spaced apart relationship; a sealing frame disposed between the first group and the second group and configured to maintain the spaced apart relationship and form a sealed volume between the first plurality of foam catalyst blocks and the second plurality of foam catalyst blocks; a support frame having a support surface and an opening and configured to support the first group and the second group, the first group and the second group being secured to the support surface such that the opening is disposed adjacent the sealed volume between the first group and the second group, the sealed volume and the opening providing a passageway for gas flow; a catalyst bed module comprising: a vessel defining a reaction zone having a feed inlet and a treated gas outlet, said reaction zone including said catalyst bed module, said treated gas outlet being fluidly connected to said passage; A reactor comprising:

2. 2. The reactor of claim 1, wherein the sealing frame includes a transverse element and an extended rim bypass element, the transverse element surrounding the sealed volume and supporting maintaining the spaced apart relationship, the extended rim bypass element extending outwardly from and perpendicular to the transverse element over a length and supporting forming a first gas-tight seal along a first outer edge of the first back surface of one or more catalyst blocks of the first plurality of foam catalyst blocks and forming a second gas-tight seal along a second outer edge of the second back surface of one or more catalyst blocks of the second plurality of foam catalyst blocks, the one or more catalyst blocks of the first plurality of foam catalyst blocks and the second plurality of foam catalyst blocks forming at least a portion of an outer periphery of the first group and the second group.

3. 3. The reactor of claim 2, wherein the first front side, the first top side, the first bottom side, the first side and the first other side of a portion of the first plurality of catalyst blocks and the second front side, the second top side, the second bottom side, the second side and the second other side of a portion of the second plurality of catalyst blocks are substantially open and uncovered, thereby permitting gas flow to the first and second plurality of foam catalyst blocks, respectively, and the portion of the first and second plurality of foam catalyst blocks form part of an outer periphery of the first and second groups, respectively.

4. 3. The reactor of claim 2, wherein said first back sides of said first plurality of foam blocks are substantially open and uncovered except for said first outer edge, thereby permitting gas flow into said sealed volume, and said second back sides of said second plurality of foam blocks are substantially open and uncovered except for said second outer edge, thereby permitting gas flow into said sealed volume.

5. 3. The reactor of claim 2, wherein said first perimeter covers from 1 to 40% of said first surface area and said second perimeter covers from 1 to 40% of said second surface area.

6. 1. A catalyst bed module comprising: a first group including a first plurality of foam catalyst blocks, each of the first plurality of foam catalyst blocks being bounded by a first front side having a first surface area with an opposing first back side, a first top side having an opposing first bottom side, and a first side having an opposing first other side; a second group adjacent to the first group and including a second plurality of foam catalyst blocks, each of the second plurality of foam catalyst blocks being bounded by a second front side having a second surface area with an opposing second back side, a second top side having an opposing second bottom side, and a second side having an opposing second other side, the first back side of the first plurality of foam catalyst blocks and the second back side of the second plurality of foam catalyst blocks opposing each other in a spaced apart relationship; a sealing frame disposed between the first group and the second group and configured to maintain the spaced apart relationship and form a sealed volume between the first plurality of foam catalyst blocks and the second plurality of foam catalyst blocks, the sealing frame including a transverse element configured to encircle the sealed volume and maintain the spaced apart relationship, and an extended rim bypass element extending outwardly from and perpendicular to the transverse element over a length; a support frame having a support surface and an opening, the support frame configured to support the first group and the second group, the first group and the second group secured to the support surface such that the opening is disposed adjacent the sealed volume between the first group and the second group, the sealed volume and the opening providing a passageway for gas flow; A catalyst bed module comprising:

7. 7. The catalyst bed module of claim 6, wherein the extended rim bypass element forms a first airtight seal along a first outer edge of the first back surface of one or more catalyst blocks of the first plurality of foam catalyst blocks and forms a second airtight seal along a second outer edge of the second back surface of one or more catalyst blocks of the second plurality of foam catalyst blocks, and the one or more catalyst blocks of the first plurality of foam catalyst blocks and the second plurality of foam catalyst blocks form at least a portion of an outer periphery of the first group and the second group.

8. 8. The catalyst bed module of claim 7, wherein the first front side, the first top side, the first bottom side, the first side and the first other side of a portion of the first plurality of catalyst blocks and the second front side, the second top side, the second bottom side, the second side and the second other side of a portion of the second plurality of catalyst blocks are substantially open and uncovered, thereby permitting gas flow to the first plurality of foam catalyst blocks and the second plurality of foam catalyst blocks, respectively, and the portion of the first plurality of foam catalyst blocks and the portion of the second plurality of foam catalyst blocks form part of an outer perimeter of the first group and the second group, respectively.

9. 8. The catalyst bed module of claim 7, wherein said first back surface of said first plurality of foam blocks is substantially open and uncovered except for said first outer edge, thereby permitting gas flow into said sealed volume, and said second back surface of said second plurality of foam blocks is substantially open and uncovered except for said second outer edge, thereby permitting gas flow into said sealed volume.

10. 1. A process for the selective catalytic reduction of nitric oxide compounds contained in a gas stream containing a concentration of NO, a concentration of NO2, or a concentration of both compounds, comprising: introducing the gas stream into a reaction zone defined by a vessel, the reaction zone comprising: a catalyst bed module having a first group comprising a first plurality of catalyst blocks and a second group comprising a second plurality of catalyst blocks; and a sealing frame disposed between the first group and the second group and configured to maintain a spaced apart relationship and form a sealed volume between the first plurality of foam catalyst blocks and the second plurality of foam catalyst blocks, each catalyst block of the first plurality of catalyst blocks and the second plurality of catalyst blocks comprising a front side having an opposing back side, a top side having an opposing bottom side, and a side having an opposing other side, the top side, side, and other side of the first plurality of catalyst blocks and the second plurality of foam catalyst blocks forming an outer periphery of the first group and the second group are uncoated, and the first plurality of catalyst blocks and the second plurality of catalyst blocks are configured to remove the nitric oxide composition; directing the flow of the gas stream to the front side, the top side, the side, and the other side of each of a first plurality of foam catalyst blocks and a second plurality of foam catalyst blocks forming the periphery of the first group and the second group, respectively, wherein the sealing frame comprises a transverse element configured to surround the sealed volume and maintain the spaced apart relationship, and an extended rim bypass element extending outwardly from and perpendicular to the transverse element for a length, the extended rim bypass element configured to direct the flow of the gas stream from the top side, the side, and the other side into the sealed volume; passing said gas stream through said catalyst bed module under deNOx reaction conditions; The NO concentration, ２ or both compounds. ２ recovering a treated gas stream having reduced concentrations of argon, argon dioxide, argon sulphate, argon phosphate, argon iodide, argon nitrate, argon phosphate iodide ... The process includes:

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