Catalyst system and method for removing HCN from off-gas of a fluid cracking unit, and FCC unit assembly including said catalyst system

Abstract

A system and method for removing HCN from the flue gas of an FCC process (and / or generated in the catalytic system reaction itself) so that final HCN emissions are satisfactory, while avoiding undesirable levels of NO. x The method avoids other pollutants contained in the exhaust gas, such as HCN and NO. x a fluid catalytic cracking (FCC) unit generating flue gas containing HCN and NO x and a catalytic device disposed in the flue gas line for removing HCl. The catalytic device has one or more SCR catalyst articles, such as a platinum group metal (PGM)-free or PGM-containing dual-function SCR catalyst, or a combination of each. The assembly can be provided with an ammonia feeder and, optionally, an HO feeder, with associated injection for delivery into the flue gas upstream of the catalytic article.

Description

[Technical Field]

[0001] The present invention relates to a method and system for removing contaminants, including hydrogen cyanide (HCN), from off-gas generated in a combustion unit, such as a fluid catalytic cracking unit. [Background technology]

[0002] Fluid catalytic cracking (FCC) units are the primary conversion units present in many refineries worldwide. FCC units are highly flexible and can upgrade feedstocks containing many components ranging from light, hydrogenated, low-sulfur vacuum gas oil (VGO) to heavy, high-sulfur residues. Additionally, FCC feedstocks may contain heavy streams from other refining units, such as coker gas oil, as well as low-value slops of various compositions. Thus, in the FCC process, heavy hydrocarbon fractions are cracked to produce lighter, more valuable products (e.g., gasoline, distillates, and C2-C4 olefins and saturated hydrocarbons).

[0003] NO FCC from such units x and SO x Much attention has been paid to controlling SO (and particulate) emissions. FCC unit design and additives have been improved to minimize SO x and NO xHowever, more recently, hydrogen cyanide (HCN) emissions, which can be present in the flue gas of some FCC units at up to approximately 150 ppm, have come under scrutiny. FCC processes are a known source of HCN gas emissions in petroleum refineries. Such emissions can be problematic in that, if left unaddressed, HCN is a highly toxic, nitrogen-containing volatile organic compound (VOC) that can pose a significant threat to the human environment. On the other hand, efforts to address HCN emissions can result in deviations in other pollutants generated by such combustion units. Furthermore, at temperatures below 78°F, hydrogen cyanide is a colorless or pale blue liquid (hydrocyanic acid), whereas at higher temperatures, it is a colorless gas. Thus, HCN cyanide is highly volatile and therefore easily mixes with air when emitted from FCC units. Therefore, there is a responsibility to ensure that HCN levels do not rise to levels harmful to the environment and / or individuals.

[0004] Therefore, it is important to address the possibility that the atmosphere may reach undesirable levels of HCN after FCC processing. x , VOCs, CO, NO x The demand to reduce emissions of other pollutants such as, for example, carbon monoxide, uranium, and uranium dioxide must still be addressed to meet regulatory requirements regarding pollutants released into the atmosphere from combustion units.

[0005] Prior art, for example, US Pat. No. 1,137,8278, describes a flue gas (herein the terms "flue gas" and "exhaust gas" are used interchangeably) purification system for modern power plants, which is equipped with an oxidation catalyst for the removal of volatile organic compounds (VOCs) and carbon monoxide (CO), and further for the removal of nitrogen oxides (NO x A system with a reduction catalyst for selective catalytic reduction (SCR) of NO is described. xThe removal of VOCs and CO is typically accomplished using two different catalyst compositions.

[0006] Selective catalytic reduction (SCR) is a catalytic reaction in which nitrogen oxides, NO and NO, are catalytically reacted with ammonia, typically acting as a reducing agent (NH-SCR), to form elemental nitrogen and water, according to the reaction scheme below: 4NO+4NH3+O2→4N2+6H2O (1) NO + NO2 + 2NH3 → 2N2 + 3H2O (2) 6NO2+8NH3→7N2+12H2O (3) 2NO2+4NH3+O2→3N2+6H2O (4)

[0007] Reactions 1 and 2 are the main reactions, and each NO x For each mole of NO, one mole of ammonia is consumed. Reactions 3 and 4 x The majority of this occurs with the gas present as NO2. A catalyst is used to drive the reaction at temperatures between 150 and 480°C (300 and 900°F). The most common type of SCR catalyst is based on vanadium pentoxide (V2O5) as the active compound on a titanium dioxide (TiO2) support system.

[0008] Reaction 1 is known as the "standard SCR reaction," reaction 2 is known as the "fast SCR reaction," and reactions 3 and 4 are known as the "NO2 SCR reactions."

[0009] The aforementioned U.S. Pat. No. 1,137,8278 further describes a system for removing volatile organic compounds, carbon monoxide, and nitrogen oxides from off-gas, comprising an ammonia source, a means for introducing ammonia into a catalytic article having an SCR function, and a catalytic article having both an oxidation function and an SCR function, the catalytic article comprising a catalytic substrate and a catalytic composition comprising at least one platinum group metal and / or at least one platinum group metal oxide, at least one oxide of titanium, and at least one oxide of vanadium, thereby achieving a high NO2 to NO ratio. xIt is emphasized that such removal is achieved even in a comparative manner.

[0010] Prior art WO 14 / 063738 discloses a method for purifying sulfur dioxide-containing off-gas by selectively oxidizing carbon monoxide and volatile organic compounds in the off-gas while reducing sulfur trioxide production, comprising contacting the off-gas with an oxidation catalyst comprising palladium supported on a carrier and vanadium oxide. If the off-gas also contains nitrogen oxides, the off-gas is contacted with a catalyst effective for the selective reduction of nitrogen oxides.

[0011] WO 14 / 124830 describes harmful carbon monoxide, organic volatile compounds and NO x A flue gas or exhaust gas containing carbon monoxide and NO is treated with a layered catalyst. x A method and catalyst for simultaneous removal of NH3 by contacting with a layered catalyst, wherein a first layer comprises an oxidation catalyst and a lower layer comprises an ammonia-SCR catalyst (NH3-SCR catalyst), is disclosed.

[0012] WO 17 / 220473 discloses a method for preparing a monolith catalyst for reducing nitrogen oxides, volatile organic compounds, and carbon monoxide in off-gases. The catalyst comprises at least one platinum group metal, vanadium oxide, titania, and optionally tungsten oxide. The problem described as being solved by this method is to avoid the formation of a platinum group metal concentration gradient across the entire axial and vertical length of the substrate. It is described that gradient formation is particularly problematic when the substrate is pre-loaded with vanadium oxide and then impregnated with the platinum group metal.

[0013] U.S. Patent Application Publication No. 2014 / 0241969 describes a method for reducing the amount of HCN emitted to the atmosphere from an FCC unit having a regenerator and a means for collecting and supporting catalyst particles. The method includes adding a catalyst to the regenerator flue gas before it enters the collection means and precipitating the catalyst in the collection means to form a catalyst bed. Ammonia or an ammonia precursor is optionally added to the flue gas. The HCN in the flue gas is reacted in the presence of water and oxygen in the flue gas, and optionally ammonia or an ammonia precursor, in the presence of the catalyst bed at 200°C to 800°C to reduce the amount of HCN, and the reduced HCN flue gas is ultimately released to the atmosphere. The catalyst is described as one or more supported transition metal or lanthanide metal catalysts.

[0014] U.S. Pat. No. 5,173,278 discloses a method for treating small amounts of HCN and NO produced by catalyst regeneration in fluid catalytic cracking of petroleum gas oils. x describes the denitration of flue gas containing both HCN and NO by reaction with HCN under high temperature conversion conditions. x with a catalyst active for the selective catalytic reduction of the undesired HCN and at least a portion of the NO, the catalyst being selected from the group consisting of supported transition metals and crystalline zeolites, the contacting being carried out to remove the undesired HCN and at least a portion of the NO. x HCN and NO x The patent also describes a method for converting HCN and NO into a mixture containing nitrogen gas by reaction between HCN and NO, as shown below, and releasing the denitrified flue gas into the atmosphere. x The estimated reaction is also described. HCN + NO → N2 gas + CO + CO2 + H2O

[0015] U.S. Patent Application Publication No. 2018 / 0111084 describes a method for treating cyanides, hydrocarbons, and NO x An integrated purification method for industrial exhaust gases is described, which are industrial exhaust gases containing multiple pollutants. The method is capable of purifying cyanides, hydrocarbons, nitrogen oxides (NO xThe process involves treating exhaust gas containing pollutants such as cyanides (R-CN), hydrocarbons (C), etc. in a gas-liquid separator to separate free fluids, then mixing them with air blown by a blower, preheating them in a heating unit, and then sending them to an SCC reactor for selective catalytic combustion reaction. This reference also describes the simultaneous denitration of cyanides (R-CN), hydrocarbons (C), etc. in the same reactor by placing catalysts with different functions without placing individual selective catalytic reduction denitration reactors and additional ammonia. x H y ) and nitrogen oxides (NO x The transformation of three pollutants, including .

[0016] The above-mentioned prior art describes several approaches to addressing multi-component pollutants in exhaust gases, some of which involve treating the exhaust gas within an FCC unit before it exits the fractionation or main distillation column and is sent to the FCC unit's stack. In any of the above-mentioned approaches, when prioritizing the removal of one or more pollutants, care should be taken to avoid creating other problems for the passage of one or more other pollutants in the exhaust stream. For example, in addition to HCN being present in the exhaust of an FCC process, it may also be generated in an NH3-SCR system as a by-product of such a reaction, depending on the temperature and other exhaust stream and system characteristics. A discussion of this potential generation of HCN is found, for example, in Zengel et al., "Emission of Toxic HCN During NOx Reactions," in x Removal by Ammonia SCR in the Lean-Burn Natural Gas Engines”, Angew. Chem Int Ed, 2020, 59, p.14423-14428, as well as Elsener et al, “HCN production from formaldehyde during the selective catalytic reduction of NO xwith NH3 over V2O5 / WO3-TiO2”, Applied Catalysis B:Environmental, 2021, 281, p. 119462.

[0017] Thus, the art provides a method for efficiently removing HCN from exhaust gases, such as those generated in FCC processes (and / or generated in the catalytic system reaction itself), thereby reducing undesirable levels of other pollutants (e.g., NH, NO) that may be present in the exhaust gases. x It is believed that the final HCN emissions must be satisfactory while avoiding harmful contaminants (e.g., CO and various VOCs).

[0018] Furthermore, because HCN emissions can be difficult to detect, there is a need in the art to be able to efficiently monitor HCN emissions. [Prior art documents] [Patent documents]

[0019] [Patent Document 1] U.S. Patent No. 1,137,8278 [Patent Document 2] International Publication No. 14 / 063738 [Patent Document 3] WO 14 / 124830 [Patent Document 4] International Publication No. 17 / 220473 [Patent Document 5] US Patent Application Publication No. 2014 / 0241969 [Patent Document 6] U.S. Patent No. 5,173,278 [Patent Document 7] US Patent Application Publication No. 2018 / 0111084 [Patent Document 8] US Patent Application Publication No. 2013 / 0104519 [Patent Document 9] U.S. Patent Application Publication No. 2011 / 635010 [Patent Document 10] U.S. Patent No. 11635010 [Patent Document 11] U.S. Patent No. 7431904 [Patent Document 12] U.S. Patent No. 8323600 [Non-Patent Document]

[0020] [Non-Patent Document 1] Zengel et al., "Emission of Toxic HCN During NOx Removal by Ammonia SCR in the Lean-Burn Natural Gas Engines", Angew. Chem Int Ed, 2020, 59, p.14423-14428 [Non-Patent Document 2] Elsener et al, "HCN production from formaldehyde during the selective catalytic reduction of NOx with NH3 over V2O5 / WO3-TiO2", Applied Catalysis B:Environmental, 2021, 281, p.119462 [Summary of the Invention]

[0021] The present invention addresses the above-mentioned need in the art by providing systems and methods for efficiently removing HCN from exhaust gases generated in an FCC process (and / or generated in the catalytic system reaction itself) so that final HCN emissions are satisfactory, while attempting to avoid undesirable levels of other pollutants in the exhaust gases while doing so. While the systems and methods described below are primarily directed to removing HCN (and preferably other pollutants) contained in off-gases from FCC units, the features of the present invention can be used to address other combustion units that have the potential to release HCN into the environment, such as gas turbine combustion units.

[0022] Accordingly, disclosed herein is a system well suited for the removal of HCN from exhaust gases, such as the removal of HCN contained in the off-gas of a fluid catalytic cracking (FCC) unit.

[0023] While the catalyst system of the present invention may be dedicated solely to the removal of HCN from such off-gases, the catalyst system of the present invention preferably also removes HCN and NO x and more preferably, in conjunction with the removal of NO x , in conjunction with the combined removal of hydrocarbons and VOCs in general (with an emphasis on HCN), and CO.

[0024] SCR catalyst and / or dual function catalyst (i.e., NO x When dealing with the reduction of HCN to off-gas streams over catalytic systems containing catalysts capable of reducing HCN and oxidizing CO and VOCs, there are two main routes to HCN decomposition. Catalytic oxidation: 4HCN + 5O2 → 4CO2 + 2N2 + 2H2O (5) Hydrolysis:HCN+H2O→NH3+CO (6)

[0025] As discussed above in connection with US Pat. No. 5,173,278, it is also speculated that there are additional (denitrification) pathways for the degradation of HCN, which may be as follows: 2HCN + 4NO → 3N2 (gas) + CO + CO2 + H2O (7)

[0026] Accordingly, disclosed herein are systems for removing HCN from FCC unit off-gases (such as systems for treating off-gases exiting or flowing downstream from a fractionation or main distillation column), and preferably systems for use in simultaneously removing multiple pollutants, such as volatile organic compounds (other than focusing on HCN removal), carbon monoxide, and nitrogen oxides, from FCC off-gases. The systems preferably include a reductant source, such as ammonia, and means for introducing the reductant source (such as ammonia) to one or more catalyst articles having SCR functionality, and preferably one or more catalyst articles having both oxidation and SCR functionality (or dual function catalysts "DFCs"), the DFC catalyst articles including a catalyst substrate and a catalyst composition preferably comprising the following: at least one platinum group metal and / or at least one platinum group metal oxide ("PGM"), at least one oxide of titanium, and at least one oxide of vanadium, and a washcoat (or other suitable catalyst to provide the desired material). and other means) are provided in and / or on the walls of the catalyst substrate (said PGMs being represented by Pt, Pd, Rh, Ir, Ru and Os, with a subset of Pt, Pd and Rh being preferred in this circumstance, most preferably having Pd as the predominant PGM, such as Pd alone, Pd and Pt, or Pd and Rh), and preferably also having means for measuring the amount of HCN between the outlet end of the catalyst article and the stack or at the stack (either directly or indirectly by monitoring an indicator level of another exhaust gas constituent), and preferably also having means for adjustment based on such monitoring.

[0027] Optionally, a non-dual function SCR catalyst article ("SCRart"), such as one that does not contain PGMs functioning as an oxidizer, may be used alone or in combination with a DFC, such as an SCRart located upstream or downstream of a DFC or between a pair of DFCs. Alternatively, a DFC may be used alone or in combination with an SCRart, such as an SCRart located upstream or downstream of a SCRart or between a pair of SCRarts.

[0028] Also disclosed is a method for removing HCN (preferably in conjunction with the removal of one or more other pollutants, such as other volatile organic compounds, nitrogen oxides, and carbon monoxide) from off-gases, such as those generated in an FCC. The method utilizes a system according to the present invention, and in some method embodiments, the performance of the HCN reduction is monitored, preferably through analysis to determine the HCN flowing downstream of the system.

[0029] Embodiments of the present invention include items 1-30 listed below, including the various alternative combinations described therein. 1. An assembly comprising: HCN and NO x a fluid catalytic cracking (FCC) unit generating a flue gas comprising: HCN and NO in the flue gas x a catalyst system comprising a catalytic device disposed along the flue gas (such as at a location downstream of a fractionation column or main distillation column of an FCC unit) for removing a first source comprising ammonia or an ammonia precursor; a second source comprising HO; an injector for supplying one or each of the first and second sources to the flue gas upstream of at least one of the one or more catalytic articles. 2. The assembly of embodiment 1, wherein the one or more catalyst articles of the catalytic device comprise an SCRart. 3. The assembly of any one of aspects 1 to 2, wherein the one or more catalytic articles of the catalytic device comprise a DFC. 4. The assembly of any one of aspects 1-3, wherein the one or more catalyst articles of the catalytic device comprise each of a DFC and an SCRart. 5. The assembly of any one of aspects 1-4, comprising at least three catalyst articles such that the catalytic device is characterized by at least two DFCs combined with one SCRart, or at least two SCRarts combined with one DFC. 6. The assembly of embodiment 5, wherein the catalytic device comprises, from upstream to downstream, two DFCs and one SCRart in an arrangement of DFC / SCRart / DFC or SCRart / DFC / DFC or DFC / DFC / SCRart. 7. The assembly of embodiment 6, wherein the sequence is DFC / SCRart / DFC. 8. The assembly of embodiment 6 or 7, wherein the upstream DFC and the downstream DFC have different PGM loadings. 9. The assembly of any one of aspects 1-5, wherein the catalytic device comprises two SCRarts and one DFC in an arrangement from upstream to downstream of SCRart / SCRart / DFC or SCRart / DFC / SCRart or DFC / SCRart / SCRart. 10. The assembly of embodiment 9, wherein the sequence is SCRart / SCRart / DFC. 11. The assembly of any one of aspects 1-10, wherein one of the one or more catalytic articles of the catalytic device comprises vanadium. 12. The assembly of any one of aspects 1-11, further comprising means for determining the level of HCN either directly or indirectly relative to the level of HCN passing downstream of the catalytic device. 13. The assembly of embodiment 12, wherein the means for determining comprises a sensor for directly determining the level of HCN passing downstream of the catalytic device. 14. The assembly of any one of aspects 1-13, further comprising a control unit; and means for determining a level of HCN, wherein the means for determining comprises either a direct (preferably in situ) determination of the level of HCN or an indirect (preferably in situ) determination, such as comprising a CO sensor in communication with the control unit for extrapolation of the amount of HCN level by the control unit. 15. The assembly of any one of aspects 1-14, further comprising a container, wherein the first and second sources are stored one inside the other, and a first supply line extending from the container to the injector for injecting each of the first and second sources together into the flue gas. 16. The assembly of aspect 15, wherein the first and second sources are urea and H2O mixed with the urea in the container, or aqueous ammonia in the container. 17. The assembly of any one of aspects 1-16, further comprising a control unit, wherein the first and second sources are fed to a distribution system having a valving system in communication with the first and second sources, one or more feed lines of the distribution system communicating the first and second sources with the injection device to enable one or both of the first and second sources to be fed to the injection device for injection into the flue gas passing towards the catalytic device, the control unit in communication with sensing means for monitoring one or more properties of the flue gas and the valving system for adjusting the relative percentages of the first and second sources reaching the flue gas. 18. The assembly of embodiment 17, wherein the control unit is configured to adjust the flow from the second source based on one or more sensed properties of the flue gas to provide a variable range of water vapor volume fraction (e.g., 0-15% by volume) in the flue gas flowing to the catalytic device based on a desired level of hydrolysis determined by the control unit. The "0" in the 0-15% range represents the control unit not adding HO (e.g., by adjusting a valve control) to the HO being injected into the flue gas by the injection device. 19. As an additional featured embodiment (Embodiment 19), there is provided a catalytic device for use in removing flue gas generated in a fluid catalytic cracking unit, the catalytic device comprising at least three catalytic articles, a first catalytic article of the at least three catalytic articles being an SCR catalyst article (SCRart) that does not contain a platinum group metal material (PGM), and a second catalytic article of the at least three catalytic articles being an SCR catalyst that includes a PGM to provide a dual function SCR catalyst (DFC), the at least three catalytic articles featuring, in any order, at least two DFCs combined with one SCRart, or at least two SCRarts combined with one DFC. 20. The catalytic device of embodiment 19, wherein the catalytic device comprises at least two DFCs combined with one SCRart. 21. The catalytic device of aspect 19 or 20, wherein the upstream to downstream arrangement of the catalytic articles is DFC / SCRart / DFC. 22. A further embodiment (Embodiment 22) of the present invention is a method of operating the assembly of any one of Embodiments 1 to 18, comprising the steps of generating flue gas in the FCC unit and generating HCN and NO x and passing the flue gas through the catalytic device to remove 23. The method of embodiment 22, further comprising sensing to determine or estimate the level of HCN downstream of the catalytic device. 24. An additional embodiment (Embodiment 24) of the present invention involves a method for removing HCN from the flue gas of an FCC unit, comprising passing the flue gas through and contacting it with any one of the catalytic devices of Embodiments 19-21 (and optionally measuring the level of HCN downstream of the catalytic device). 25. Yet another embodiment (Embodiment 25) of the present invention is a method for removing HCN from a flue gas stream, comprising: The flue gas is passed through a catalytic system including a catalytic device disposed along the flue gas to remove HCN and NO in the flue gas. xwherein the catalytic device has one or more catalyst articles, one of the one or more catalyst articles being a platinum group metal material (PGM)-free SCR catalyst article (SCRart) or an SCR catalyst article containing PGM to provide a dual function SCR catalyst article (DFC); monitoring the level of HCN in the flue gas exiting the catalyst system; The present invention involves a method including: 26. The method of embodiment 25, wherein the flue gas is generated by an FCC unit. 27. Yet another aspect (Aspect 27) of the present invention is an assembly, comprising: HCN and NO x a fluid catalytic cracking (FCC) unit generating a flue gas comprising: a control unit; HCN and NO in the flue gas x a catalytic device disposed along said flue gas for removing PGMs such as palladium, said catalytic device comprising at least one dual function catalyst article (DFC) comprising a substrate which is a corrugated substrate supporting a catalytic composition which comprises, in addition to said PGMs such as palladium, oxides of vanadium and titanium, and preferably further comprises at least one or any combination of oxides of tungsten, oxides of molybdenum, and silica (preferably tungsten alone or tungsten and silica (in the latter case primarily SiO2-doped TiO2 is used as the support)); an example of a DFC comprising: 50 to 10,000 ppmw (parts per million by weight), calculated as pure precious metal, based on the total weight of the catalyst article; the platinum group metal preferably being palladium; 60 to 90 wt. % of at least one oxide of titanium, calculated as TiO2, based on the total weight of the catalyst article, the at least one oxide of titanium being titanium dioxide; and 0.1 to 17 wt. % of at least one oxide of vanadium, calculated as VO5, based on the total weight of the catalyst article, the at least one oxide of vanadium being preferably vanadium pentoxide; the total weight of the catalyst article being the sum of the amount of the at least one platinum group metal, the amount of the at least one oxide of titanium, the amount of the at least one oxide of vanadium, and the amount of the catalyst substrate (if present, plus the amount of the aforementioned "at least one or any combination of tungsten oxide, molybdenum oxide, and silica"); a sensor for directly or indirectly monitoring the level of HCN in the flue gas exiting the catalytic device; The assembly comprises: 28. The assembly of aspect 27, further comprising: a first source having ammonia or an ammonia precursor material; a second source comprising HO; supply means for supplying one or both of the first source material and the second source material to the flue gas upstream of the catalytic device; and a control unit configured to adjust the supply means to vary the amount of first and second source materials supplied to the flue gas. 29. The assembly of any one of aspects 27 to 28, further comprising a PGM-free second SCR catalyst article (SCRart) within the catalytic device. 30. The assembly of aspect 27, 28, or 29, wherein the catalytic device comprises at least three catalytic articles, a first catalytic article of the at least three catalytic articles being an SCR catalyst article (SCRart) that does not contain a platinum group metal material (PGM), and a second catalytic article of the at least three catalytic articles being the DFC, and wherein the at least three catalytic articles are characterized by at least two DFCs combined with one SCRart or at least two SCRarts combined with one DFC.

[0030] The systems and methods described herein for treating FCC flue gases are directed to the efficient removal of HCN so as to avoid the release of undesirable amounts of HCN, and such removal also preferably involves the removal of other hydrocarbon contaminants, such as NO. x This is achieved under embodiments of the present invention by the simultaneous removal of any one, or any combination of portions thereof, or all of the contaminants typically associated with FCC off-gas (such as the off-gas flowing downstream of the fractionation or main distillation column in an FCC unit), such as pollutants, carbon monoxide, and other contaminants that may be found in the off-gas generated in an FCC unit.

[0031] Systems and methods under the present invention for removing HCN (and preferably further pollutants such as those classifiable as volatile organic compounds, carbon monoxide and nitrogen oxides) from combustion gases such as FCC off-gas are described in more detail below, and the invention includes all embodiments shown above and below, individually and, where appropriate, in combination with one another. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a schematic diagram of an example of an FCC unit assembly of the present invention comprising an FCC unit and an associated catalyst system. [Figure 2A] 2 illustrates in more detail the embodiment of the catalyst system shown in FIG. [Figure 2B] 2B is a diagram similar to FIG. 2A, but showing an alternative catalyst system embodiment. [Figure 2C] 1 illustrates another catalyst system embodiment. [Figure 3A] The configuration of each catalytic reactor along the FCC flue gas is shown. [Figure 3B] The configuration of each catalytic reactor along the FCC flue gas is shown. [Figure 3C] The configuration of each catalytic reactor along the FCC flue gas is shown. [Figure 3D]The configuration of each catalytic reactor along the FCC flue gas is shown. [Figure 3E] The configuration of each catalytic reactor along the FCC flue gas is shown. [Figure 3F(a)] The configuration of each catalytic reactor along the FCC flue gas is shown. [Figure 3F(b)] The configuration of each catalytic reactor along the FCC flue gas is shown. [Figure 3F(c)] The configuration of each catalytic reactor along the FCC flue gas is shown. [Figure 3G] The configuration of each catalytic reactor along the FCC flue gas is shown. [Figure 3H] The configuration of each catalytic reactor along the FCC flue gas is shown. [Figure 3I] The configuration of each catalytic reactor along the FCC flue gas is shown. [Figure 3J] The configuration of each catalytic reactor along the FCC flue gas is shown. [Figure 3K] The configuration of each catalytic reactor along the FCC flue gas is shown. [Figure 3L] The configuration of each catalytic reactor along the FCC flue gas is shown. [Figure 4] 1 illustrates an alternative embodiment of a catalyst system under the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0033] An example FCC unit assembly 20 is partially and schematically illustrated in Figure 1, including an FCC unit 22 and an associated catalyst system 24. In Figure 1, the FCC unit 22 is partially illustrated (some standard FCC components, such as an upstream regenerator, are not shown, in order to focus on the components of the associated flue gas stream that leads to the atmosphere). Accordingly, Figure 1 schematically illustrates a conventional FCC unit reactor 26 that processes a feed (e.g., heavy oil) to generate a reactor effluent (e.g., an overhead hydrocarbon gas stream) that exits the reactor along line 28.

[0034] The gas stream flowing along line 28 is fed to a main distillation (or fractionation) column 30, where the hydrocarbonaceous gas stream is distilled into desired products (e.g., light cycle oil), with higher boiling hydrocarbons being removed from main distillation column 30 via bottoms conduit 32 and lower boiling components, including HCN, being removed from column 30 via conduit 34. Conduit 34 routes these lower boiling components, including HCN, to catalyst system 24, where, after catalytic treatment, the effluent gas is routed downstream, e.g., to a stack or additional processing zone (neither shown), via outlet conduit 35, and typically ultimately to the atmosphere 36.

[0035] 1 and 2A, catalytic system 24 includes catalytic reactor 38, a more detailed description of the configuration of which is provided in more detail below. The exhaust gas or flue gas stream passing through conduit 34 enters inlet end 40 of catalytic reactor 38 and is then processed by catalytic reactor 38, after which the processed gas stream exits outlet end 42 of reactor 38 along outlet conduit 35 (an example of conduit 35 could be an outlet stack or outlet stack section that routes FCC unit off-gas to atmosphere 36, or could involve a line leading to another processing zone).

[0036] 1 and 2A show additional components of catalyst system 24, including a reductant source 46 (e.g., NH3 for use with an NH3-SCR (not shown in FIGS. 1 and 2A) forming part of catalytic reactor 38). Source 46 feeds into a supply line 48 that leads to a flow controller 50 that controls the amount of reductant supplied (if present, as flow controller 50 can be controlled from a shut-off setting to a maximum variable flow setting). The downstream end of supply line 48 feeds into a valve unit 52 (shown in this embodiment as a multi-way valve, such as one with variable settings of (off / left flow only / right flow only / and both flow)).

[0037] 1 and 2A further show valve unit 52 in fluid communication with a second (e.g., water for hydrolysis) source 54 (e.g., a heated steam generator to facilitate hydrolytic decomposition in reactor 38, as described below) via supply line 56. Line 56 is also shown with a flow controller 58, similar to flow controller 50 described above, which also feeds valve unit 52.

[0038] A feed line 60 extends from valve unit 52 and is in fluid communication with the flue gas flowing in line 34 at the illustrated injection location 61. Although not shown (as such equipment is conventional in nature), the feed relationship to the downstream end of feed line 60 includes an injection device used to spray, atomize, or otherwise inject material flowing through line 60 so that it mixes with the flue gas flowing in line 34. Such injection devices for distributing ammonia or ammonia precursor into the flue gas (preferably well before reaching catalytic reactor 38 to facilitate complete dispersion) include distribution arrays or grids, examples of which can be found, for example, in U.S. Patent Application Publication No. 2013 / 0104519, as well as U.S. Patent Application Publication No. 2011 / 635010, which describes ammonia injector grids of various resolutions, and which are incorporated herein by reference for informational purposes only.

[0039] 1 and 2A further illustrate the location of the injection system upstream (with respect to the exhaust flow path leading to the discharge) of the inlet 40 of the reactor 38. Such injection locations may be limited to upstream of the most upstream SCR component (whether DFC or SCRart), but could potentially also be configured to supply such ammonia or ammonia precursor upstream of the most upstream SCR component (some examples of which are described below), such as a distribution system supplying each of the first and second sets of SCR components (any combination of SCR components described in the DFC and SCRart mentioned, including direct supply both upstream of and between any pair of catalytic means or SCR components representing the catalytic reactor 38).

[0040] 1 and 2A also show sensor devices 62, 64, and 66. Sensor device 62 is shown upstream of injection location 61 in feed line 60 to flue gas flow conduit 34 and thus upstream of inlet 40 of catalytic reactor 38. Sensor device 64 is shown downstream of injection location 61 and upstream of inlet 40 of reactor 38. Sensor device 66 is shown downstream of reactor outlet 42 to facilitate operation of sensor means 66 used to sense one or more properties of the exiting flue gas. Each of sensor devices 62, 64, and 66 is designed to monitor one or more properties of the passing gas stream, such as temperature and / or content levels of one or more pollutants. For example, outlet sensor device 66 is configured to monitor HCN slip through reactor 38 by direct sample monitoring. Suitable HCN sensors that can represent sensor device 66 include those positioned in-line to receive the flue gas flowing in line 35, either by monitoring directly in line 35 (such as provided in the exit stack of an FCC unit) or via a redirected flue gas flow (a branch line for the sample flue gas), or those that can receive and analyze a sample drawn from said flue gas line 35 (in which case sensor device 66 is in the form of a sample supply means used in the sensing process). For example, sensor device 66 (or sampling means 66 in some circumstances) can be represented by a Fourier transform infrared spectroscopy sensor ("FTIS sensor") that is in line 35, receives the flue gas from line 35 via a branch line, or is at another location to receive a supply sample.Additional sensor device 66 embodiments include detection means for directly monitoring the levels of HCN passing downstream of the catalytic reactor 38, such as those capable of detecting and quantifying HCN in the flue gas using one or more of a variety of analytical methods, either in situ or via sample delivery techniques, such as involving time-of-flight ion mobility spectroscopy (ToF IMS), VIS spectroscopy (e.g., UV-VIS or ultraviolet-visible spectroscopy), gas chromatography coupled with mass spectrometry (GC / MS), liquid chromatography coupled in parallel with mass spectrometry (LC / MS), mass spectrometry, and electrochemical methods (e.g., potentiometry using a cyanide-specific electrode, ion chromatography, or direct current measurement).

[0041] An alternative technique for monitoring the level of HCN (or means for monitoring the level of HCN) is to sense the level of CO leaving the catalytic reactor 38 and monitor indirectly by extrapolation (e.g., according to hydrolysis equation (6) above, the decomposition of HCN by hydrolysis increases CO, and therefore the level of CO can provide information on the level of HCN (preferably, in terms of flue gas VOCs, this may also increase the level of CO in some cases, adding a potential variable reduction control requirement)).

[0042] While three sensor means or devices 62, 64, and 66 are shown in connection with facilitating monitoring of reactor 38 performance parameters, fewer or more sensor means or devices are contemplated by the present invention, such as only one sensor device (either sensor devices 62 or 64) upstream of catalytic reactor 38 and one sensor device 66 downstream. Alternatively, only sensor device 66 may be relied upon, functioning with or without other upstream or downstream catalytic systems (e.g., using only sensor device 66 to monitor only HCN in a dedicated HCN catalytic reactor 38, or to monitor outlet pollutants). Additionally, each of the above-described sensor means or devices 62, 64, and 66 may have one or more individual sensors that serve to provide the desired information used in such monitoring at a designated location area (e.g., a combination of various sensed flue gas components, or a combination of one or more flue gas components with one or more (or any combination of) physical properties of the flue gas, such as flue gas temperature, flow rate, and line pressure).

[0043] 3A-3L show the FCC flue gas path 34 (downstream of the main distillation column - in some FCC unit systems, a SO 4 gas trap is used to reduce contaminants that may be present before reaching the distillation column). x The configuration of each catalytic reactor for use along the distillation column (note that removal of possible contaminants is performed upstream of the distillation column, such as with a scrubber or cyclone catalytic reaction) is shown.

[0044] Before describing various alternative embodiments of catalytic reactor 38 in catalyst system 24, some definitions are provided to facilitate a better understanding of the catalyst attributes featured under the present invention (as well as some additional definitions regarding the interrelationships of the catalyst attributes in the context of catalyst system 24 described herein and / or regarding FCC unit assembly 20 in general).

[0045] That is, a "catalytically active composition" (or, as shortened, "catalyst" or "catalyst composition" depending on the context) is a substance or mixture of substances capable of converting one or more components of exhaust gas into one or more other components. Examples of such catalysts include, for example, oxidation catalysts or oxidation catalyst compositions capable of converting volatile organic compounds and carbon monoxide into carbon dioxide. Another example of such a catalyst is, for example, a selective catalytic reduction catalyst (SCR catalyst) or an SCR catalyst composition designed to convert nitrogen oxides into nitrogen and water (e.g., an SCR catalyst composition typified by the catalytically active composition vanadium pentoxide). In the context of the present invention, a catalyst article with SCR functionality is a catalyst article comprising an SCR catalyst or an SCR catalyst composition.

[0046] A "catalyst support material" is a material onto which a catalytically active composition can be immobilized (e.g., immobilized on the exterior of an externally porous particle and / or within the pores of such a particle), e.g., titanium dioxide, alumina, silica, or molecular sieves such as zeolites / zeotypes. Such catalyst support materials are therefore designed to receive a catalyst or catalyst composition and may be provided together with a catalyst-supported substrate, as described below, for attachment (as in a washcoat or dry impingement spray). It is also noted that materials such as inorganic base metal oxides like Al2O3 (aluminum oxide or alumina), SiO2, TiO2, CeO2, ZrO2, VO5, La2O3, and zeolites can have various uses in washcoat configurations. These uses include use as a "catalyst support material" according to the above, as well as use as a washcoat promoter or stabilizer, although some may also exhibit catalytic activity in their own right.

[0047] Molecular sieves are materials with uniformly sized pores, i.e., very small holes. The diameter of these pores is similar in size to small molecules, so that larger molecules cannot penetrate or adsorb, but smaller molecules can. In the context of the present invention, the molecular sieve is preferably a zeolite. Zeolites consist of corner-sharing tetrahedral SiO4 and AlO4 units. They are also called "silicoaluminates" or "aluminosilicates." In the context of the present invention, these two terms are used interchangeably.

[0048] As used herein, the term "non-zeolitic molecular sieve" refers to a corner-sharing tetrahedral framework in which at least some of the tetrahedral moieties are occupied by elements other than silicon or aluminum. When some, but not all, silicon atoms are replaced by phosphorus atoms, they are called "silicoaluminophosphates" or "SAPOs." When all silicon atoms are replaced by phosphorus, they are called aluminophosphates or "AlPOs."

[0049] "Zeolite framework type," also referred to as "framework type," represents a corner-sharing network of tetrahedrally coordinated atoms. It is common to classify zeolites according to their pore size, defined by the ring size of the largest pore opening. Zeolites with large pore sizes have a maximum ring size of 12 tetrahedral atoms, zeolites with medium pore sizes have a maximum ring size of 10, and zeolites with small pore sizes have a maximum ring size of 8 tetrahedral atoms. Known small-pore zeolites belong to the AEI, CHA (chabazite), ERI (erionite), LEV (levinite), AFX, and KFI frameworks, among others. Examples of large pore sizes are faujasite (FAU) framework-type zeolites and zeolite beta (BEA).

[0050] A "zeotype" includes any family of materials based on the structure of a particular zeolite. Thus, a particular "zeotype" includes, for example, silicoaluminates, SAPOs, and AIPOs based on the structure of a particular zeolite framework type. Thus, for example, chabazite (CHA), silicoaluminates SSZ-13, Linde R, and ZK-14, silicoaluminophosphate SAPO-34, and aluminophosphate MeAlPO-47 all belong to the chabazite framework type. Those skilled in the art know which silicoaluminates, silicoaluminophosphates, and aluminophosphates belong to the same zeotype. Furthermore, zeolites and non-zeolitic molecular sieves belonging to the same zeotype are listed in the International Zeolite Association (IZA) database. Those skilled in the art can use this knowledge and the IZA database without departing from the scope of the claims.

[0051] The silica to alumina ratio (SiO2:Al2O3) of a zeolite is hereinafter referred to as the "SAR value."

[0052] A "catalyst-supported substrate" is a support onto which a catalyst or catalyst composition is deposited to form the final catalyst. Examples include monolith catalyst support structures such as the well-known honeycomb wall-flow, flow-through, and corrugated sheet monoliths. The catalyst-supported substrate is designed to allow exhaust gas to flow along it to facilitate the desired form of catalytic contact with the catalyst composition provided thereon. Thus, the catalyst-supported substrate is a support substrate for the catalyst or catalyst composition (and may also be a support substrate for the catalyst support material when utilized to hold the catalyst or catalyst composition (as is often the case in washcoat applications)).

[0053] A "washcoat" as used herein is an aqueous suspension of a catalytically active composition (e.g., an aqueous suspension having a catalytically active composition, such as those described above, and a catalyst support material, such that after application of the washcoat to a catalyst-supported substrate, e.g., after calcination, the catalytically active composition is provided in and / or on the catalyst support material, and the combination is mutually supported on the catalyst-supported substrate).

[0054] A washcoat applied to a catalyst-supported substrate is called a "coating." It is also possible to apply two or more washcoats to a catalyst-supported substrate. Those skilled in the art know that two or more washcoats can be applied to a single catalyst-supported substrate by "layering" or "zoning," and that layering and zoning can also be combined. In layering, washcoats are applied successively to the catalyst-supported substrate. The washcoat applied first and therefore in direct contact with the catalyst-supported substrate is the "underlayer," and the washcoat applied last is the "upper layer." In zoning, a first washcoat is applied to the catalyst-supported substrate from a first side A of the catalyst-supported substrate toward the other side B, but only up to the end point between sides A and B, rather than along the entire length of the catalyst-supported substrate. A second washcoat is then applied to the catalyst-supported substrate, starting from side B and ending at the end point between sides B and A. The endpoints of the first and second washcoats do not have to be the same, but if they are, both washcoat zones are adjacent to each other. However, if the endpoints of two washcoat zones, both located between face sides A and B of the catalyst-supported substrate, are not the same, there may be a gap between the first washcoat zone and the second washcoat zone, or they may overlap. As mentioned above, layering and zoning can be combined, for example, if one washcoat is applied along the entire length of the catalyst-supported substrate and the other washcoat is applied only from one face side to the endpoint between the two face sides.

[0055] In the context of this invention, "washcoat loading" is the mass of catalytically active composition, and optionally the mass of binder, if the washcoat includes a binder, per volume of catalyst-supported substrate.

[0056] Those skilled in the art know that washcoats are prepared in the form of suspensions and dispersions.

[0057] Suspensions and dispersions are heterogeneous mixtures containing solid particles and a solvent. The solid particles do not dissolve but are suspended throughout the volume of the solvent, remaining freely suspended in the medium. If the solid particles have an average particle size of 1 μm or less, the mixture is called a dispersion; if the average particle size is greater than 1 μm, the mixture is called a suspension. A washcoat in the sense of the present invention comprises a solvent, usually water, suspended or dispersed particles represented by particles of one or more catalytically active compositions, and optionally particles of at least one catalyst support material, as described above. This mixture is often called a "washcoat slurry." The slurry is applied to a catalyst-supported substrate and subsequently dried to form a coating as described above. In the context of the present invention, the term "washcoat suspension" is used to refer to a mixture of a solvent and particles of one or more catalytically active compositions, and optionally particles of at least one catalyst support material, regardless of their individual or average particle size. This means that in the "washcoat suspension" of the present invention, the individual particle size as well as the average particle size of the one or more catalytically active solid particles may be less than, equal to, and / or greater than 1 μm.

[0058] The term "mixture" as used in the context of the present invention is a material consisting of two or more different substances physically combined, with each component retaining its own chemical properties and structure. Despite the fact that there is no chemical change in the components, the physical properties of the mixture, such as its melting point, may differ from those of the components.

[0059] In the context of the present invention, a "catalyst article" includes a catalyst-supported substrate and a catalyst or catalyst composition comprising the catalyst-supported substrate. As a few examples, the catalyst article under the present invention includes, for example, the following (1) and (2) (including respective examples of their formation techniques): 1. Coated substrate monolith: a) Monolith formation (example): - Preparing the (aqueous) inert material from which the monolith will be formed, e.g. cordierite. The inert material and the monolith material are equivalent. Forming a monolith (can be done by extrusion). The monolith thus obtained is dried and fired. (The monolith thus obtained has channels.) b) Preparation of the washcoat: A water-based washcoat is prepared that includes catalytically active material (such as copper-loaded zeolite, or vanadium on titania, or a precious metal) and optionally a binder, and optionally additives (such as rheology modifiers). c) Coating of the monolith: Coating the monolith obtained in a) with the washcoat obtained in b). Coating methods: for example, dip coating (immersing the monolith to be coated in the slurry) or allowing it to penetrate through the monolith under vacuum or pressure. · Optional: Remove excess washcoat (by vacuum or pressure). Dry and calcinate the coated monolith. Result: A catalyzed substrate monolith with the washcoat (dried and calcined) layered in or on the monolith's walls. 2. Extruded substrate monolith: - Preparing an (aqueous) slurry of inert monolith material (e.g. cordierite) and catalytically active material and optionally binder / rheology modifier. The mixture is extruded. The result: a catalyzed substrate monolith whose channel walls consist of a uniformly distributed inert matrix material and catalytically active material. In this case, there is no separation between the inert matrix material and the catalytically active material, since a homogeneous mixture is extruded.

[0060] An example of a catalyst article according to the present invention is a "dual function catalyst" (DFC), the term "dual" being used because the catalyst has both oxidation and reduction functions; the DFC can oxidize volatile organic compounds and carbon monoxide to carbon dioxide and water. Additionally, the DFC can reduce nitrogen oxides to nitrogen and water in the presence of ammonia. This means that the DFC also has an SCR reduction function, or more specifically, an NH3-SCR reduction function.

[0061] A "catalytic device" is represented by one of many catalyst articles. When represented by multiple catalyst articles, the catalytic device may comprise a single catalyst-supported substrate with the catalyst articles represented by different zones and / or layers on the catalyst-supported substrate, or it may comprise separate catalyst articles in coplanar contact (adjacent catalyst substrate supports or adjacent substrate casings of catalyst articles), or it may comprise separate catalyst articles separated by a flue gas flow, such as one with an intermediate or bridging flow conduit containing separate catalyst articles stored within a common housing or passageway.

[0062] A "catalytic reactor" includes a catalytic device (having one or more catalytic articles) and means for supplying flue gas to contact one or more catalytic articles, e.g., a housing having suitable conduits for directing flue gas into catalytic contact with the catalytic articles, or a portion of a flue gas conduit in general that receives the catalytic device.

[0063] The terms "exhaust gas," "flue gas," or "off-gas," as used in the context of this invention, refer to gases emitted as a result of the combustion of fuels such as natural gas, gasoline, petroleum, biodiesel blends, diesel fuel, fuel oil, or coal. Thus, FCC off-gas (or flue gas or exhaust gas) is the gas generated under an FCC process.

[0064] "Unpurified" or "dirty" exhaust gas, flue gas, or off-gas is gas, as defined above, that has not yet passed through an exhaust gas cleaning system (eg, a catalytic system).

[0065] "Upstream" and "downstream" are terms relative to the normal flow direction of off-gas in an exhaust pipeline. "An object, article, or apparatus 1 located upstream of an object, article, or apparatus 2" means that object 1 is positioned near the source of the off-gas, i.e., near the outlet of the main distillation column of an FCC, with respect to the flue gas flow. In this case, object 2 is located "downstream" of object 1; that is, object 2 is farther from the source of the off-gas than object 2. The direction of flow is from the source of the venting off-gas to the atmosphere, such as at a chimney (or stack) or exhaust pipe or conduit outlet.

[0066] The "inlet end" of the catalyst article is the end that faces the combustion source, and the "outlet end" is the end that faces the outlet to the stack or atmosphere with respect to the exhaust stream.

[0067] The reaction that reduces nitrogen oxides to nitrogen and water is well known as the SCR reaction, and the SCR reaction is often known as the reaction used with ammonia (NH3-SCR). This is the reaction that converts unburned hydrocarbons (HC) in the exhaust gas into NO. xThis can be compared to "HC-SCR," which detoxifies HC, a decomposition product of the fuel, and therefore uses the HC as a reducing agent (as opposed to the type that relies on ammonia as in "NH-SCR" systems). A preferred system according to the present invention for many envisioned environments, including those that process flue gas from FCC units, is an "NH-SCR" system, and in such uses, the present invention also preferably includes an ammonia source and means for introducing ammonia (by "ammonia" is meant a direct ammonia feed or a precursor to an ammonia feed to the flue gas that provides ammonia in the flue gas conduit). In the discussion below, references to "SCR" are in the context of SCR components of the NH-SCR type, unless otherwise specified.

[0068] The ammonia source can be ammonia itself or an ammonia precursor capable of releasing ammonia. The ammonia source is preferably selected from aqueous ammonia, anhydrous ammonia, aqueous urea, aqueous ammonium formate, and ammonium carbamate, and mixtures thereof, more preferably anhydrous ammonia, aqueous ammonia, or aqueous urea. Anhydrous ammonia (NH3) can be used as either a gas or a liquid. Suitable ammonia precursors include urea, ammonium carbamate, and ammonium formate, preferably urea. The precursor hydrolyzes to ammonia upon heating. For example, aqueous urea hydrolyzes at temperatures above 130°C, thereby releasing ammonia. The off-gas from an FCC unit during normal operation can be expected to have a temperature above 130°C, and therefore, aqueous urea readily hydrolyzes when introduced into the SCR catalyst in such a plant. Aqueous ammonia can also be effectively decomposed when injected as fine particles into a gas stream at at least 350°C.

[0069] Anhydrous ammonia, aqueous ammonia, or ammonia precursor is preferably stored in a container and added to the off-gas stream as needed to be introduced to the inlet side of the target catalyst article. Storage containers and means for introducing anhydrous ammonia, aqueous ammonia, or ammonia precursor at the inlet side of an SCR catalyst are well known in the art and can be applied to the system of the present invention without departing from the scope of the claims. In the context of the present invention, the term "means for introducing ammonia" encompasses means for introducing ammonia itself as well as means for introducing an ammonia precursor. Preferably, the container contains anhydrous ammonia, aqueous ammonia, or aqueous urea. A preferred means for introducing aqueous ammonia or aqueous ammonia precursor is via an injector located upstream of the catalyst device, i.e., on the inlet side. These means for supplying reagents to the flue stream include distribution arrays or grids (e.g., "ammonia injection grids"), examples of which can be found, for example, in U.S. Patent Application Publication No. 2013 / 0104519, as well as U.S. Patent No. 11,635,010, which describes ammonia injector grids of various resolutions and is incorporated herein by reference for informational purposes only.

[0070] Aspects of the present invention also involve controlling the use of HO to provide the desired level of HCN hydrolysis in the catalyst system, which can include the use of HO found in aqueous ammonia sources, such as the aqueous ammonia and urea solution sources described above. Aqueous ammonia is often supplied as a 29% ammonia solution, while aqueous urea is typically supplied as a 32.5% urea solution. Under embodiments of the present invention, means are provided to vary the percentage, such as by adding HO to the ammonia feed added to the off-gas stream (e.g., at a downstream location including a feed pipe feeding the urea or ammonia solution vessel, or mixing in the flue passage, or in conjunction with ammonia injection at a grid or similar injection location), to provide additional HO for the hydrolytic decomposition of HCN according to equation (6) above.

[0071] In a preferred embodiment of the invention, the means for introducing ammonia into the off-gas is a means for introducing aqueous ammonia or aqueous urea via an ammonia injection grid such as those described above.

[0072] The catalyst-supported substrate is selected from a flow-through substrate, a wall-flow substrate, and a corrugated substrate. The wall-flow substrate and the flow-through substrate may be composed of an inert material such as silicon carbide, aluminum titanate, cordierite, a metal, or a metal alloy. The inert material can be, for example, extruded directly and then coated with at least one washcoat containing the catalyst composition and / or by a dry impinging process to attach the catalyst material to the catalyst-supported substrate. Alternatively, the inert material for the wall-flow or flow-through substrate can be mixed with the catalyst material or its precursor to form a paste, and the mixture can be extruded to obtain the catalyst article as defined above in one step. Furthermore, the substrate can be selected from a ceramic candle filter, a bag filter, or catalyst pellets or beads.

[0073] Such catalyst-supported substrates are known to those skilled in the art and are commercially available. In a preferred embodiment, the catalyst-supported substrate is a corrugated substrate monolith.

[0074] In a preferred embodiment, the corrugated substrate monolith is a high silica content glass paper or E-glass fiber paper, provided with at least one washcoat or impinged with a catalyst composition.

[0075] Methods for preparing washcoats or impinging catalyst compositions onto catalyst-supported substrates, as well as methods for producing extruded catalyst articles, are well known to those skilled in the art and can be applied in the context of the present invention without departing from the scope of the claims.

[0076] The catalyst or catalyst composition can be located "in-wall" (e.g., a catalyst composition having a particulate support material, such as porous alumina particles carrying a platinum group metal, with a particle size that allows significant access into the porous walls of the catalyst-supported substrate), and / or "on-wall" (e.g., a particle size that primarily bridges the intra-wall pores of the wall, such as a catalyst composition support material supported primarily on the walls of the catalyst-supported substrate, such as a surface coating applied to channels similar to those in the catalyst-supported substrate). Preferably, the catalyst or catalyst composition is located within the walls of the catalyst-supported substrate, or on the walls of the catalyst-supported substrate, or a combination of both within and on the walls. For the aforementioned corrugated catalyst-supported substrates of high-silica glass paper or E-glass fiber paper, an application that includes (at least partially) an intra-wall application of the catalyst composition is preferred, as it can help strengthen the overall catalyst article.

[0077] The catalyst or catalyst composition of the catalytic article having both oxidation and SCR functions preferably comprises at least one platinum group metal and / or at least one platinum group metal oxide, at least one oxide of titanium, and at least one oxide of vanadium, examples of which can be found in the aforementioned WO 14 / 124830.

[0078] The at least one platinum group metal and / or at least one platinum group metal oxide is selected from ruthenium, rhodium, palladium, osmium, iridium, platinum, and their oxides. When two or more platinum group metals are present, they can be physical mixtures, alloys, or mixtures of physical mixtures and alloys of the platinum group metals and / or their oxides. For example, when platinum and palladium are selected, they can be present as a) physical mixtures, b) alloys of platinum and palladium, where neither pure platinum nor pure palladium is present, or c) alloys of platinum and palladium as mentioned in b), as well as pure platinum and / or pure palladium. When oxides of two or more platinum group metals are present, they can be present as a) mixtures of oxides of the same metal in various oxidation states, b) mixtures of oxides of one or more different metals in various oxidation states, c) oxides of alloys, or d) combinations of mixtures of oxides of one or more metals in various oxidation states and oxides of different metals. Furthermore, the platinum group metals and platinum group metal oxides described above can coexist.

[0079] Preferably, the at least one platinum group metal is selected from palladium, platinum, iridium, and mixtures, alloys, oxides, and mixtures of alloys, oxides, and physical mixtures. Even more preferably, the at least one platinum group metal is palladium and / or palladium (II) oxide, PdO.

[0080] In a preferred embodiment, the catalyst-supported substrate is a corrugated substrate, and the catalyst or catalyst composition is located within and / or on the walls of the catalyst substrate, preferably both within and on the walls, as described above. In this embodiment, the total weight of the catalyst article is the sum of the amount of at least one platinum group metal and / or at least one platinum group metal oxide, the amount of at least one titanium oxide, the amount of at least one vanadium oxide, and the amount of the catalyst-supported substrate. The amounts of at least one platinum group metal and / or at least one platinum group metal oxide, the amount of at least one titanium oxide, and the amount of at least one vanadium oxide in this embodiment are shown below.

[0081] The at least one platinum group metal and / or platinum group metal oxide is present in the catalyst article in an amount of 50 to 10,000 ppmw, preferably 100 to 3,000 ppmw, and even more preferably 200 to 2,000 ppmw, calculated as pure precious metal and based on the total weight of the catalyst article. The unit "ppmw" stands for "parts per million by weight." Preferably, the at least one platinum group metal is palladium. As used herein, a "high" loading of the at least one platinum group metal and / or platinum group metal oxide is considered to be above the upper half of the stated 200 to 2,000 range, and a "low" loading is considered to be within the lower half of the 200 to 2,000 range. That is, a low loading is 200 to 1,100 ppmw, and a high loading is greater than 1,100 to 2,000 ppmw.

[0082] When present in the catalyst article, the at least one oxide of titanium is present in an amount of 60-90 wt. %, preferably 65-85 wt. %, and more preferably 70-80 wt. %, calculated as TiO2, based on the total weight of the catalyst article. In one embodiment, the at least one oxide of titanium is titanium dioxide (TiO2). Suitable titanium dioxides contain at least 95 wt. %, preferably at least 98 wt. %, and even more preferably at least 99.5 wt. % anatase. The remainder of TiO2, adding up to 100 wt. %, is represented by rutile and / or brookite, preferably rutile. The at least one oxide of titanium serves as a support material for the washcoat.

[0083] When present, the at least one oxide of vanadium is present in an amount of 0.1 to 17 wt. %, preferably 0.6 to 5 wt. %, and more preferably 1.8 to 3.6 wt. %, calculated as VO, based on the total weight of the catalyst article. In one embodiment, the at least one oxide of vanadium is vanadium pentoxide (VO).

[0084] In one embodiment, the applied material (by application of a first washcoat) further comprises at least one oxide of tungsten. The at least one oxide of tungsten is present in an amount of 0.001 to 10 wt. %, preferably 2 to 7 wt. %, more preferably 2.5 to 6 wt. %, and most preferably 2.7 to 3.3 wt. %, calculated as WO, based on the total weight of the catalyst article. In one embodiment, the at least one oxide of tungsten is tungsten trioxide (WO). In this implementation, the total weight of the catalyst article is the sum of the amounts of at least one platinum group metal and / or at least one platinum group metal oxide, at least one oxide of titanium, at least one oxide of vanadium, at least one oxide of tungsten, and the respective amounts of the catalyst article.

[0085] To control the efficiency of the off-gas cleaning, the amount of HCN (preferably also NO) is adjusted between the outlet end of the catalytic device and the chimney or at the chimney of the off-gas cleaning system. x In all embodiments of the present invention, the amount of HCN (preferably also NO x and / or the amount of ammonia slip), can be measured preferably at the chimney.

[0086] The respective amounts of HCN can be determined either directly or indirectly according to the techniques described above. Additionally, the amount of HCN reaching the inlet of the catalytic reactor can also be determined and used to determine the HCN reduction capacity across the catalytic device.

[0087] NO x Measurements of NO (if performed in addition to the determination of HCN) can be determined, for example, by chemiluminescence detection (CLD), Fourier transform infrared spectroscopy (FTIR), or infrared spectroscopy (IR). x These means for determining the amount of are well known to those skilled in the art and may be applied to the present invention without departing from the scope of the claims.

[0088] As stated above NOx Alternatively, or in addition to, and as an adjunct to measuring HCN, it is also possible to measure ammonia slip (NH3 slip) between the outlet end of the catalyst article and the stack or at the stack of the off-gas cleaning system. The ammonia that is emitted at the stack of the off-gas cleaning system is known as "ammonia slip." Ammonia slip is usually measured by FTIR. Ammonia slip measurement can be performed together with the above HCN determination, and can also be used to measure NO between the outlet end of the catalyst article and the stack or at the stack. x This can be done in addition to, or instead of, measuring the amount of

[0089] Optionally, the amount of CO emitted between the outlet end of the catalytic device and the chimney or at the chimney can also be measured. This measurement is preferably made in addition to measuring HCN and NO between the outlet end of the catalytic device and the chimney or at the chimney. x This can be done in addition to measuring the amount of CO and / or NH3 slip. A suitable means for measuring CO is, for example, a non-dispersive infrared analyzer (NDIR). Means and methods for measuring CO are known to those skilled in the art and can be applied in the context of the present invention without departing from the scope of the claims. x As mentioned above for measuring the amount of CO and / or ammonia slip, measurements of CO are also preferably made at the chimney.

[0090] The CO measurements can also be extrapolated to attempt to determine the level of HCN to be taken into account (e.g., through an extrapolation decision of the control unit knowing the expected hydrolysis level for a (preferably also controlled) supply volume of water vapor in the flue gas, based on information stored in the control unit about the operation and supply type and amount of the FCC unit, and sensing of any upstream catalytic articles thereof, with possible additional considerations such as the expected level of VOCs involved).

[0091] In one embodiment of the present invention, the DFC is a gas turbine engine for the removal of HCN (preferably converting HCN to NO). xand preferably together with further pollutants such as volatile organic compounds, carbon monoxide, etc. In this embodiment, the means for introducing ammonia is located sufficiently upstream of the catalyst article to promote good and complete volumetric dispersion upon reaching the catalyst article, and the means for introducing ammonia is the only catalyst article with SCR functionality in the catalyst system (for removal of HCN, and preferably together with further pollutants such as volatile organic compounds, carbon monoxide, etc.). x Means for measuring any one or a combination of CO, ammonia slip, or emitted CO are provided between the outlet end of the DFC and the chimney or in the chimney, preferably in the chimney.

[0092] In another implementation of the invention, a PGM-free SCR catalyst article (or "SCRart") is present alone or together with a DFC (upstream, downstream, or both). In contrast to a DFC, the SCRart has only a selective catalytic reduction function and not an oxidation function. When the SCRart is upstream of the DFC (the most upstream of the SCR components), the means for introducing ammonia is preferably located upstream of the SCRart to achieve the desired ammonia dispersion level upon reaching the SCRart. This means that in the case of an upstream SCRart / downstream DFC combination, the SCRart is located between the ammonia introduction means and the DFC. In this embodiment, the means for measuring the amount of HCN is preferably located downstream of the DFC (after the gas has passed through each catalyst article), or a combination of sensing between the SCRart and the DFC and downstream of the DFC. Such HCN sensing is performed to detect the amount of HCN in the pollutant NOx. x , ammonia slip, and CO emitted, and the sensing preferably includes a sensor located between the outlet end of the DFC and the chimney, or even further upstream between the SCRart and the DFC, for initial insight into the amount, or reduction (e.g., HCN) made by the SCRart, before the flue gas reaches the downstream DFC where it is further processed for subsequent release downstream of the downstream DFC.

[0093] The possible sensor positioning described above for the upstream SCRart and downstream DFC can also be applied to the reverse arrangement of the most upstream DFC and downstream SCRart.

[0094] Thus, in yet another embodiment of the present invention, the SCR catalyst article is located downstream of the DFC. When the SCR is downstream of the DFC, the means for introducing ammonia is preferably located immediately upstream of the DFC or upstream of both the DFC and the SCR. In other words, in embodiments of the present invention, the means for introducing ammonia is located upstream of the DFC, or also upstream of the DFC and between the DFC and the SCR.

[0095] In this embodiment, the means for measuring the amount of HCN is preferably provided downstream of the SCRart (after the gas has passed through each catalyst article), or a combination of sensing between the SCRart and the DFC, as well as downstream of the SCRart. x , ammonia slip, and / or emitted CO, and the sensing preferably includes one or more sensors located between the outlet end of the SCRart and the chimney, or also located between the upstream DFC and the SCRart, for initial insight into the amount or reduction (e.g., HCN) made by the DFC before the flue gas reaches the downstream SCRart where it is further processed for subsequent release downstream of the downstream SCRart.

[0096] In yet another embodiment of the present invention, one or more DFCs are present in combination with one or more SCR catalyst articles ("SCRarts"). Examples (arranged from upstream to downstream) include a DFC-SCRart-DFC arrangement (representing one SCRart and multiple DFCs), or a SCRart-DFC-SCRart arrangement (representing one DFC and multiple SCRarts), or a SCRart-SCRart-DFC (representing another example of multiple SCRarts and one DFC). Suitable representatives of SCRarts are the DNX® series of SCR catalysts available from Umicore Company (for convenience, the registered trademark DNX® is repeated below as the abbreviation "DNX"). Suitable representatives of DFCs are the DNO® series catalysts, also available from Umicore Company (for convenience, the registered trademark DNO® is repeated below as the abbreviation "DNO").

[0097] Examples of DNX "non-binary" SCR configurations are described above and can also be found in the catalytic device configurations described in U.S. Patent No. 7,431,904 to Hoj. Furthermore, the DFCs described herein include the DNOs described above; examples of this type of catalytic device are described above and in WO 14 / 124830 to Castellino et al. and WO 17 / 220473 to Pedersen et al. As seen therein, DNX catalysts can thus include corrugated, fiber-reinforced titanium dioxide (TiO) catalyst substrate support plates, which are uniformly impregnated with active ingredients such that the entire ceramic plate is composed of a uniform distribution of tungsten trioxide (WO) and vanadium pentoxide (VO) in the manner described above. See also the above discussion of representative weight percentages for the mentioned catalyst article components, such as VO, TiO, and WO of DNO, as well as PGM. The DNO may have a configuration similar to that described above for the DNX, with the addition of a zone (e.g., a downstream zone of the DFC in an exemplary embodiment of the invention) characterized by the addition of an impregnated precious metal solution (as with impregnation with a PGM, such as the palladium solution in the example described in WO 17 / 220473) (in conjunction with providing dual functional attributes).

[0098] The term "means for measuring the amount of HCN (or preferably NO) x , ammonia slip, or emitted CO)" or "measuring means" below preferably refers to a measuring means downstream of the catalytic article having the SCR catalytic function located closest to the chimney (or, as mentioned above, additional preliminary monitoring between an upstream / downstream pair of SCR components (e.g., any permutation of a DNX and DNO pair) in addition to measuring after the most downstream SCR component).

[0099] Various SCR catalyst articles (both PGM-free SCRarts and PGM-containing DFCs) can include materials such as zeolites or metal oxides or mixtures of zeolites and metal oxides as the SCR catalyst or catalyst composition and / or as material supports therefor.

[0100] Suitable zeolites are, for example, small pore aluminosilicate zeolites selected from ACO, AEI, AEN, AFN, AFT, AFX, ANA, APC, APD, ATT, BIK, CDO, CHA, DDR, DFT, EAB, EDI, EPI, ERI, ESV, ETL, GIS, GOO, IHW, ITE, ITW, LEV, KFI, MER, MON, NSI, OWE, PAU, PHI, RHO, RTH, SAT, SAV, SIV, THO, TSC, UEI, UFI, VNI, YUG, ZON, and mixtures and intergrowths thereof. Preferably, the zeolite is selected from AEI, AFT, AFX, CHA, DDR, ERI, ESV, ETL, KFI, LEV, UFI, and mixtures and intergrowths thereof, and even more preferably, the zeolite is selected from AEI, CHA, AFX. Furthermore, the small pore zeolite is preferably provided containing, for example, 0.1 to 10 wt. % of a transition metal, calculated as the respective transition metal oxide, based on the total weight of the zeolite. Preferably, the transition metal is selected from Fe, Cu, and mixtures thereof, and more preferably, the transition metal is copper. Furthermore, the SAR of the zeolite used in the present invention is preferably in the following range: 5 to 50, preferably 5 to 30, and most preferably 7 to 25.

[0101] Suitable metal oxides for use in the SCR catalyst composition are, for example, mixtures of titania and vanadia oxides, as described above, which may optionally further contain other oxides such as tungsten oxide, antimony oxide, niobium oxide, molybdenum oxide, cerium oxide, lanthanum oxide, and mixtures thereof.

[0102] As used herein, NO xThe term "nitrogen oxides," also referred to as NO, refers to the total amount of nitric oxide (NO) and nitrogen dioxide (NO) present in the exhaust gas or off-gas, regardless of the relative amounts of NO and NO present in the exhaust gas or off-gas.

[0103] Thus, with reference to the above description of DFC and / or SCRart catalyst articles (i.e., non-DFC SCR catalyst articles) in catalytic reactor embodiments of the present invention, a description of several examples follows, including those shown in Figures 3A-3L. In each case described below, the SCRart referred to may be exemplified by DNX, while the DFC referred to below may be exemplified by DNO.

[0104] Also, throughout this application, similar reference numbers and letters (e.g., 38A and 38B) are used (or hundreds are added, such as 21 / 121 / 221) to facilitate reference to components that are identical or at least somewhat commonly configured or arranged among various embodiments; however, such components may vary in value or attributes from embodiment to embodiment despite commonly used reference numbers (at the actual or base level, such as 21 and 121) or letters, and, where practicable, for purposes of the present invention, in some circumstances, there is the potential for one such identical or at least somewhat commonly configured or arranged component to be interchanged with another component.

[0105] FIG. 3A shows the removal of HCN (if present, preferably NO) from the flue gas of an FCC unit. x 1 and 2A) for use in the flue gas purification system. The catalytic reactor 38A (an example of the catalytic reactor 38 generally shown in FIGS. 1 and 2A) is shown for use in the flue gas purification system. The catalytic reactor 38A is an example of the catalytic reactor 38 generally shown in FIGS. 1 and 2A) ...

[0106] The catalytic reactor 38A is shown generally as including a housing 68 having an inlet 40 for receiving flue gas flowing in line 34, and within the housing 68 (in this embodiment) is housed a catalytic device 70 (limited to one catalyst article 70A in this embodiment). While the housing is shown as being oversized, the housing could also be represented by a continuation of the conduit 34, such as an extended conduit configuration suitable for in-line placement of the catalytic reactor. The catalyst article 70A, in this embodiment, is in the form of an SCRart only (i.e., a non-DFC catalyst article). As shown in FIG. 3A , the housing 68 has a length L from upstream to downstream (inlet to outlet), which, in a preferred embodiment (this embodiment and others described herein), is also the inlet end to outlet end of the catalytic device (70 in this embodiment).

[0107] Thus, flue gas flowing through the housing 68 and catalytically contacting the catalytic device 70A exits the housing 68 through outlet 42 and passes through outlet conduit 35 (e.g., a portion of the exhaust stack or leading to the exhaust stack for off-gas discharge by the FCC unit). The SCRart can be any one of the non-DFC forms of SCR (e.g., SCR components without an active PGM oxidation catalyst) described above / below. A sufficiently suitable SCRart catalytic device 70A is a "DNX" SCRcat having the composition and configuration described above (e.g., PGM-free, non-dual function). Thus, in a DNX catalyst article, the DNX has the aforementioned monolith or integrated structure (e.g., its own outer casing for stability and protection when placed within the housing 68 in addition to the monolith corrugation). Suitable examples of such corrugated monolith materials with casings can be found in U.S. Pat. No. 8,323,600.

[0108] Additionally, the materials of catalytic reactor 38 generally (and thus including catalytic reactor 38A as well as all of catalytic reactors 38B-38M described below) are preferably designed for use in the off-gas stream of an FCC unit (e.g., the off-gas stream after the main distillation column), which in many circumstances will be at or within a temperature range of 550°F to 800°F. Accordingly, catalytic reactor 38 (38A in this example) is designed to function properly catalytically (e.g., to produce desired levels of HCN and NO without generating undesirable by-products within the described temperature range). x (This provides a reduction in the amount of carbon dioxide produced while also avoiding excessive physical degradation, such as excessive sintering levels, in the material of the catalyst article).

[0109] FIG. 3B shows catalytic reactor 38B, designed for use in the same manner as 38A in FIG. 3A and therefore as a component of catalytic system 24 shown in FIG. 1 in the flue gas line receiving the exhaust output of an FCC unit. The difference between reactors 38A and 38B lies in the catalytic device contained within housing 68. That is, in FIG. 3B, catalytic device 72 features the use of a DFC as catalytic article 72A (instead of the above-described SCRart catalytic article 70A within housing 68). DFC catalytic article 72A can take the form of any of the DFC configurations described above / below, such as the above-described DNO (preferably having the same corrugated monolith support within a protective casing as described above in U.S. Pat. No. 8,323,600), and is the catalytic device utilized for the desired level of HCN removal (and in preferred embodiments, in conjunction with the simultaneous removal of other pollutants as described above for reactor 38A). Furthermore, although Figures 3A and 3B refer to "SCRart" and "DFC" as a means of referring to the different catalyst articles involved (also shown with different shading patterns), as noted above, suitable representative examples of SCRart include "DNX" and suitable representative examples of DFC include "DNO" (similarly for Figures 3C-3M).

[0110] 3C shows reactor 38C, similar in configuration and use within catalyst system 24 to reactors 38A and 38B above, but with a modified configuration of catalyst device 73. It includes an upstream catalyst article 74 (denoted as a DFC type, and taking any of the DFC configurations described above and below, where the aforementioned DFCs are used for HCN removal or HCN "plus" contaminant removal (e.g., HCN and NO, such as NO and / or NO). x ) is a potential option for providing a means for the downstream catalytic converter 74 to operate in a catalytic converter. FIG. 3C shows the DFC 74 occupying only a portion of the streamwise length of the housing 68, and this relative length can be adjusted to suit expected environmental characteristics (such as FCC process characteristics such as temperature and exhaust gas composition, which are often determined in large part by the feedstock being processed (e.g., cracked) in the FCC, with the HCN reduction goal being considered therein). FIG. 3C shows that approximately 50% of the catalytic device length L is occupied by the upstream catalyst article 74 (this embodiment also shows 50% of the common length L of the housing 68).

[0111] The remainder of L is shown occupied by catalyst article 76, which in this embodiment is in the form of a SCRart (e.g., DNX), and is therefore shown with 50% occupied by DFC 74 and catalyst article 76 occupying the remaining 50% of L. Again, the relative percentages of the upstream and downstream catalyst articles 74 and 76 can be varied from the illustrated 50 / 50 split to better suit the process conditions and characteristics of the FCC flue gas passing therethrough and / or thereover, and to meet desired HCN reduction targets.

[0112] Additionally, each catalyst article (i.e., 74 and 76 in this embodiment, and similarly for the catalyst article embodiments above and below) making up catalytic device 73 can take any one of the corresponding (DFC, SCRart) forms described above, in any combination possible where the environment is suitable (e.g., using different catalyst support substrate types (e.g., honeycomb catalyst support substrate on one side and corrugated sheet on the other), or using different support materials such as molecular sieves (e.g., zeolites or other microporous support particles) on one side and metal oxide particles (e.g., lanthanum-doped alumina) on the other), or can use different catalyst compositions aimed at achieving the catalytic objectives of each DFC or SCRart. Furthermore, while these various options for catalytic device 73 can represent any of the other catalytic device configurations in FIGS. 3A-3L (and 38M in FIG. 4), the aforementioned DNX and / or DNO with associated characteristics such as corrugated catalyst support substrate and catalyst composition are well suited for use in environments such as the described FCC unit flue gas environment and to achieve desired HCN reduction goals.

[0113] The catalytic reactor 38D of Figure 3D is similar in all respects to that of Figure 3C, except that the upstream / downstream relationship in its catalytic unit 77 is reversed. That is, the DFC and SCRart catalyst articles are swapped in position in the catalytic unit 77, relative to the upstream-to-downstream flow path, so that the upstream 50% of the housing 68 of the catalytic reactor 38D is occupied by the SCRart 78 and the downstream 50% is occupied by the DFC 80 (each of which may be any one of the catalyst article configurations described above, with all combinations being contemplated if circumstances are suitable (as discussed in the options in the immediately preceding paragraph)). The exemplary arrangement of Figure 3D also features DNX and DNO in the flow arrangement.

[0114] FIG. 3E illustrates a catalytic reactor 38E having a catalytic device 81G including three arrangements of catalyst articles A, B, and C, where A is either an SCRart or a DFC, B is either an SCRart or a DFC, and C is either an SCRart or a DFC. Accordingly, FIG. 3E illustrates the catalytic reactor 38E as having any of the possible variations on the options noted between an SCRart and a DFC for each of the illustrated locations A, B, and C. Some examples of such possible combinations are illustrated below in connection with FIGS. 3F(a) through 3F(c), and other combinations, while not specifically illustrated, are possible under the present invention based on the general A, B, and C representations in FIG. 3E (the possibilities for such combinations will be understood based on the discussion and illustrations above, such as the general representation in FIG. 3E and the examples seen in FIGS. 3F(a) through 3F(c) below).

[0115] 3F(a) shows an alternative embodiment in which catalytic reactor 38F(a) houses catalytic device 81, which is comprised of three catalyst articles shown in the following upstream-to-downstream arrangement: DFC 82A → SCRart 83 → DFC 82B. Again, each of the two DFCs and one SCRart may be zoned regions on a single monolith support substrate, or may be separate catalyst-supported substrate components, such as those featuring catalyst articles in a series arrangement with adjacent casings or directly adjacent catalyst-supported substrates (or multiple components within separate housings, or multiple spaced apart components with internal bridging conduits providing sequential outlet-to-inlet flow, as described below).

[0116] Also, each of the two DFCs 82A and 82B may have the same structure and composition, or they may be different. For example, one DFC may have a higher relative loading and / or a different relative length in the upstream-downstream direction. For example, one of DFCs 82A and 82B may have a "high loading" active oxidation catalyst (e.g., PGM) composition (according to the weight ranges above), while the other has a lower loading (as a "low loading" composition, also according to the weight ranges above). For example, the upstream DFC 82A may have a high loading and the downstream DFC 82B a low loading, or vice versa. The relative loading levels can be dictated by the nature (levels and / or composition) of the flue gas pollutants, such that if the nature of the flue gas and the nature of the two upstream catalyst articles (82A and 83) suggest a higher downstream PGM (e.g., palladium) loading, such as when NH3 slip through the two referenced upstream catalyst articles is expected, thereby providing an ammonia oxidation or "AMOX function," then the second downstream DFC can be provided with a higher PGM loading. Furthermore, while each of the catalyst articles is shown occupying approximately one-third of the total length, any one of the three may have a shorter or longer relative length, occupying a range of 10-60% of each division that totals 100% (e.g., 60 / 30 / 10 or 10 / 45 / 45, as some examples of the referenced division ranges), and more preferably, each division ranges from 20-40, as just a few examples of possible relative length variations among the three catalyst articles in this embodiment.

[0117] Figure 3F(b) illustrates another three-stage catalytic reactor embodiment similar to that described above in Figure 3F(a), but with a different composition of catalyst articles arranged in catalytic unit 84(a). That is, within housing 68, catalytic unit 84(a) is arranged along the flue gas flow with catalytic articles 85A→86→85B, where 85A and 85B are each an SCART-type catalytic article (e.g., each a DNX catalytic article), and catalytic article 86 is a DFC such as a DNO catalyst. As with catalytic unit 81, the construction and composition of the two catalyst articles 85A and 85B may be the same, or one may vary relative to the other (such as when each has a different SCR catalyst composition, e.g., the type of SCR composition, such as one based on DNX and the other on a different SCR composition, and / or the use of different support materials (e.g., one with a molecular sieve support material (e.g., zeolite or other microporous support particles) and the other with a metal oxide such as alumina), and / or different relative washcoat loading levels, if washcoat application is used). The range of possible lengths of the three catalyst articles described for catalytic unit 81 also preferably applies to this three-part catalytic unit 84(a). The intermediate DFC may also have a range of PGM loadings, either high or low, depending on the intended environment of use, such as the expected flue gas output composition of the FCC unit with a target for HCN reduction.

[0118] Figure 3F(c) shows another three-stage catalytic reactor embodiment having a catalytic device 84(b) with two SCRarts and one DFC, similar to Figure 3F(b), but in the order 85A→85B→86, where 85A and 85B are each of the SCRart type (e.g., each a DNX catalyst article) and the most downstream catalyst article 86 is a DFC (e.g., a DNO catalyst article). The various options discussed above regarding the various catalyst articles (such as the different SCRart-type compositions described) are equally applicable to this Figure 3F(c) embodiment of the invention.

[0119] As noted above, various other A, B, C fulfillment options for the selection of DFC or SCRart are featured under the present invention, including variations in PGM loading in DFCs where one DFC is present, or combinations of DFCs where two or three are present in A, B, and C (e.g., embodiments where A, B, and C are each a DFC or an SCRart, each of which is all the same or each or some of the group having different compositions and / or structures).

[0120] FIG. 3G illustrates a two-array catalytic reactor 38G having a catalytic device 87 similar in many respects to that described above for FIG. 3D, but with a different percentage length of each of the catalytic articles 88 and 89. As shown, the catalytic device 87 has an upstream catalytic article 88 with a greater length percentage, L, than the downstream catalytic article 89, where the catalytic article 88 is of the SCRart (e.g., DNX) type and the catalytic article 89 is of the DFC (e.g., DNO) type. The catalytic articles 88 and 89 are again shown without an intermediate gap, such as adjacent casings (or adjacent catalyst-supported substrates) within a common housing or conduit passage or different zones on a common catalyst-supported substrate. The greater percentage length of the catalytic article 88 is shown in FIG. 3G as being approximately two-thirds of L, with the remaining one-third being occupied by the DFC catalyst article 89. An alternative example of such a longer / shorter relationship includes an upstream catalyst article 88 having a % of L preferably at least 55% and up to 90%, and the remainder (10% to 45%) being a downstream catalyst article 89.

[0121] FIG. 3H illustrates another two-array catalytic reactor 38H having a catalytic device 90 similar in many respects to that described above for FIG. 3G, but with different percentage lengths of each of the catalytic articles 91 and 92. As shown, the catalytic device 90 has an upstream catalytic article 91 that has a shorter percentage of length L than the downstream catalytic article 92, with the catalytic article 91 being of the SCRart (e.g., DNX) type and the catalytic article 92 being of the DFC (e.g., DNO) type. Again, it is shown without intermediate gaps such as adjacent casings or direct contact of individual catalyst-supported substrates. The smaller percentage length of the catalytic article 91 is shown in FIG. 3H as approximately one-third of L, with the remaining two-thirds being occupied by the downstream catalytic article 92. An example includes the downstream catalytic article 92 having a percentage of L that is preferably at least 55% and up to 90%, and the remaining (10%-45%) being the upstream catalytic article 91.

[0122] FIG. 3I illustrates another two-array catalytic reactor 38I similar in many respects to that described above for FIG. 3C, but with a catalytic device 93 in which each of the catalytic articles 94 and 95 has a different percentage length. As shown, the catalytic device 93 has an upstream catalytic article 94 with a greater percentage of length L than the downstream catalytic article 95, with the downstream catalytic article 95 shown being of the SCRart (e.g., DNX) type and the upstream catalytic article 94 shown being of the DFC (e.g., DNO) type. Again, shown without intermediate gaps such as adjacent casings or direct contact of individual catalyst-supported substrates. The greater percentage of length of the catalytic article 94 is shown in FIG. 3I as being approximately two-thirds of L, with the remaining one-third being occupied by the catalytic article 95. An alternative example of such a longer / shorter relationship includes an upstream catalytic article 94 having a percentage of L preferably at least 55% and up to 90%, and the downstream catalytic article 95 having the remaining (10%-45%).

[0123] FIG. 3J illustrates another two-array catalytic reactor 38J, similar in many respects to that described above for FIG. 3C, but with a catalytic device 96 in which each of the catalytic articles 97 and 98 has a different percentage length. As shown, the catalytic device 96 has an upstream catalytic article 97 with a smaller percentage of length L than the downstream catalytic article 98, where the catalytic article 97 is of a DFC (e.g., DNO) type and the catalytic article 98 is of a SCRart (e.g., DNX) type. Again, shown without intermediate gaps such as adjacent casings or direct contact of individual catalyst-supported substrates. The greater percentage of length of the downstream catalytic article 98 is shown in FIG. 3J as being approximately two-thirds of L, with the remaining one-third being occupied by the upstream catalytic article 97. A further example preferably includes a downstream catalytic article 98 with a percentage of L of at least 55% and up to 90%, and the upstream catalytic article 97 with the remaining (10%-45%).

[0124] 3K shows another two-array catalytic reactor 38K having a catalytic device 99 similar in many respects to that described above with respect to FIG. 3D, but configured differently in that a spacing or bridge conduit 100 exists between an upstream catalytic article 101 and a downstream catalytic article 102, the flow spacing conduit 100 supplying pretreated flue gas exiting the catalytic article 101 to the downstream catalytic article 102 for further catalytic processing. In this catalytic reactor 38K, the upstream catalytic article 101 is of the SCRart (e.g., DNX) type, and the downstream catalytic article 102 is of the DFC (e.g., DNO) type. Also shown are separate housings 103 and 104 communicating via the spacing or bridge conduit 100, although a common housing 105 may be present depending on the length of the spacing and the nature of the flue gas feed (in which case reference numerals 103 and 104 may represent the respective protective casings of the catalytic articles 101 and 102 previously described). Also, in the additional bridging space between catalyst articles 101 and 102, an additional sensor is provided under embodiments of the present invention (as part of the aforementioned sensor apparatus 66 that provides sensing of gas properties, such as the level of HCN in the gas stream). Thus, while sensor apparatus 66 is preferably located downstream of catalyst article 102 for monitoring HCN and preferably in communication with a control unit, embodiments also include sensor apparatus 66 having additional means for sensing flue gas flowing between catalyst articles 101 and 102, which also preferably communicates with control unit 124 (FIG. 1) for suitable adjustments, such as the supply of water vapor to the flue gas.

[0125] 3K, feed lines 106 and 108 are also shown, with feed line 108 shown as an optional dashed line. That is, line 106 or each of lines 106 and 108 can be an example of feed line 60 shown in FIG. 1 used to supply NH or NH precursor (and various examples described above as anhydrous ammonia, aqueous ammonia, or urea solution) to downstream reactor 102 (e.g., DNO with NH-SCR functionality). Alternatively, the feed types can be different, such as an upstream 106 feed line supplying NH or NH precursor (with or without added water, or further diluted with water from its current state) and a downstream feed line 108 that is blocked or provides HO with or without ammonia (or ammonia precursor) for further hydrolytic decomposition of HCN, or lines 106 and 108 providing a mixture of HO and ammonia (or diluted or undiluted ammonia precursor), each with the same or different relative reducing agent feed levels.

[0126] Figure 3L shows a catalytic reactor 38L similar to that of Figure 3K, but in which the catalytic articles SCRart and DFC are arranged in reverse relative to the exhaust gas flow. Thus, the catalytic reactor 38L of Figure 3L includes a catalytic device 110 similar in many respects to that described above for Figure 3C, but the catalytic device 110 is configured differently in that there is a spacing or bridge conduit 112 between the upstream catalytic article 114 and the downstream catalytic article 116, the flow spacing conduit 112 supplying pretreated flue gas exiting the catalytic article 114 to the downstream catalytic article 116 for further catalytic processing. In this catalytic reactor 38L, the downstream catalytic article 116 is of the SCRart (e.g., DNX) type, and the upstream catalytic article 114 is of the DFC (e.g., DNO) type. Also, while separate housings 118 and 120 are shown communicating via a gap or bridging conduit 112, a common housing 122 may be present, depending on the length of the gap and the nature of the flue gas feed (in which case reference numerals 118 and 120 may represent protective casings for the respective catalytic articles 114 and 116). The additional bridging gap provided by conduit 112 as depicted in FIG. 3K may also be used to provide additional flow lines (e.g., two flow lines 106 and 108 shown in upstream positions relative to the catalytic articles 114 and 116) as well as additional sensor means as described above (although not labeled in FIG. 3L, the discussion above relating to sensor means 66 of the FIG. 3K embodiment is applicable, and is also applicable to catalytic reactor 38K for different potential content changes in feed lines 106 and 108 as described above).

[0127] As further seen in Figures 3K and 3L, the length of each housing (or casing) is indicated by lengths L1 and L2, respectively, and is preferably less than or equal to the length L described in other embodiments, such as (L1 + L2 ≦ 2L), such as (L1 + L2 ≦ 1.5L (L1 + L2 = L)).

[0128] Also, the various catalytic devices referenced above are shown as forming components of catalytic reactors (e.g., catalytic reactor 38A) and therefore catalytic systems (e.g., catalytic system 24A). Furthermore, as can be seen from the various embodiments above, references to "catalyst articles" in the context of the various catalytic reactor types described include various catalyst article configurations (e.g., catalyst articles 74 and 76) featuring DFC and SCR arts, such as those provided on a common, single monolith catalyst-supported substrate, or as separate, horizontally stacked, contiguous articles (e.g., preferably within a common housing or contiguous separate housings, with or without a surrounding casing adjacent in flow order), or as separate, flow-separated articles (individual, spaced-apart articles with intermediate flue gas connectors, such as interconnecting conduits).

[0129] Referring again to FIG. 2A , further description will be provided regarding catalyst system 24, including providing desired feed contents within feed line 60. FIG. 2A illustrates a control unit 124 that facilitates controlling various components within catalyst system 24 to achieve the desired feed contents and timing of the source to feed line 60 (leading to an injection device, such as one or more ammonia injector grids, as described above). Control unit 124 is shown in active communication with the sensors and / or the aforementioned components of catalyst system 24. That is, in this embodiment, control unit 124 is shown in communication with reductant (e.g., ammonia or ammonia precursor) source 46, flow controller 50, valve unit 52, second (e.g., water) source 54, flow controller 58, and each of the illustrated sensor devices 62, 64, and 66 (the dashed communication lines shown represent wired and / or wireless communication).

[0130] Control unit 124 may be part of a conventional general control unit used for the operation of the overall FCC unit, or it may be a stand-alone "feed-condition-control" unit used to provide the desired feed contents to feed line 60 (or multiple feed lines such as feed lines 106 and 108 as described above) and monitor flue gas characteristics using sensors such as the illustrated sensor devices 62, 64, and 66.

[0131] The control unit 124 may include non-transitory code or instructions stored in a machine-readable medium (e.g., memory) and used by a processor to implement the techniques disclosed herein. In certain embodiments, the control unit 124 may utilize a memory for storing instructions (e.g., code) and a processor for executing the instructions (e.g., multiple microprocessors, one or more “general-purpose” microprocessors, one or more special-purpose microprocessors, and / or some other processor configuration). The memory may store various tables and / or models (e.g., software models representing and / or simulating various aspects of the desired exhaust gas treatment conditions, as well as historical data based on past performance using similar variables such as catalyst type (e.g., whether it is a DFC and / or SCR and / or their respective lengths, as some examples), and loading amount (e.g., PGM value such as high PGM loading characteristic or low PGM loading characteristic) for known exhaust stream characteristics, such as an FCC unit). The control unit may utilize one or more types of models (e.g., software-based models executable by the processor). For example, the model can include a statistical model such as a regression analysis model. Regression analysis can be used to find a function that can model future trends within a certain margin of error. Correlation techniques can be used to find relationships between variables (e.g., extrapolating sensed amounts of CO as indicative of amounts of HCN). Data utilized with the model can also include historical data, empirical data, knowledge-based data, etc. The control unit 124 can also be hardwired to all sensing means used, or can be configured to operate solely or partially in a wireless manner with the sensing means (e.g., transmitting sensors and corresponding receiving units that provide data to a processing system (e.g., processor circuitry for performing the functions described above)). The control unit can rely on feedforward and / or feedback inputs, such as from any one (or any combination) of the sensor devices 62, 64, and 66.

[0132] 2A, the relative ratios of each source, such as the percentage of reducing agent (e.g., an ammonia source such as that outlined above) provided by source 46 compared to the amount of water (preferably in the form of superheated steam), if any, provided by second source 54, can be adjusted. Sensing means, such as HCN slip sensor 66, can be used to facilitate the desired ratio. For example, as noted above, the prior art describes the concept that HCN can be decomposed by oxidation (Equation (5) above: 4HCN + 5O → 4CO + 2N + 2HO), and / or hydrolysis (Equation (6) above: Hydrolysis: HCN + HO → NH + CO), and / or denitrification processes (Equation (7) above—generally depicted as: HCN + NO → N (gas) + CO + CO + HO).

[0133] Thus, by using sensors to monitor the composition of the flue gas at one or more suitable locations, such as, for example, placing sensor means 66 downstream of the most downstream catalyst article or at an intermediate location between there and two SCR components, and / or by utilizing additional sensor means to monitor both the inlet and outlet characteristics of the ongoing flue gas (and preferably both upstream and downstream of injection point 61 into inlet line 34, as seen by the positioning of sensing means 62 and 64), undesirable levels of other pollutants (particularly NOx) flowing in the flue gas, which are associated with the SCR properties of one or more catalytic devices. x Suitable ratios of primary and secondary sources (e.g., NH3 and HO) can be provided to achieve HCN reduction while also avoiding HCN decomposition via NH3 and HO. For example, additional water vapor can be added upstream to promote hydrolytic decomposition via NH3 and HO, particularly when upstream O2 and / or NO levels are low and deemed to reduce the HCN decomposition capabilities of NH3 and HO, and / or when exhaust gas temperatures favor catalytic reactions over other catalytic reactions.

[0134] Furthermore, the SCR reactor may be designed for the expected type of flue gas received from the combustion unit, e.g., the expected flue gas composition of a typical operating FCC unit. For example, if there is a relatively high amount of hydrolytic decomposition, increased CO emissions are expected. This increased CO emissions (in the absence of a downstream dedicated CO removal unit) can be addressed by a downstream DFC in conjunction with an upstream SCRart (or both an upstream DFC and an SCRart). Furthermore, the level of CO emissions can also be monitored by the sensor device 66 and, together with historical data stored, e.g., in the memory of the control unit 124, used to extrapolate the level of HCN slip, if any. Alternatively, or in addition, the sensor 66 can include a direct HCN monitoring means, or both a direct HCN level sensor and CO level (note that the term "sensor" as in sensor device 66 includes sensor systems that are dedicated to single parameter testing or include multiple parameter testing, such as the described CO and HCN monitoring, as well as various physical property monitoring, such as chemical, pressure, and temperature monitoring, as via the illustrated and described sensor device 66, the latter also potentially including sample collection units for use in various sensing means at the FCC unit location or sample testing off-site (ultimately another example of direct testing for HCN slip at a different sampling location)).

[0135] Furthermore, as noted above, the art recognizes the potential for HCN generation in NH-SCR systems as a by-product of such reactions, depending on temperature and other exhaust stream and system characteristics. Accordingly, the sensing and control means of catalyst system 24 may take into account the potential for HCN generation by NH-SCR during SCR processing, and, for example, reduce the supply of NH via source 46 when sensed conditions (e.g., anticipated or sensed high levels of formaldehyde in the area of ​​the SCR components that may result in the formation of undesirable HCN) indicate that undesirable HCN emissions into outlet line 35 may be expected if appropriate steps are not taken (e.g., based on the control unit's analysis of historical data and / or current or real-time sensed conditions). The two different sources 46 and 54 and associated flow controllers 50 and 58 and valve unit 52 (with possible settings for one or the other or both possible flow rates) allow for flexible manipulation of the relative ratios of the supplied feeds. Alternatively, each of sources 46 and 54 may have its own dedicated flow line, as in catalyst system 24 having means for supplying the foregoing (e.g., ammonia and HO, respectively) via supply lines 106 and 108 (or each a separate line upstream of the SCR component in the first line) shown in FIG. 3K without the need for valve unit 52, or (although not shown) an HO feed may be fed to a reservoir for the first source to increase the overall HO level, thereby providing a more diluted first source. It may be fed via a line from a first source to an injection location such as location 61 in FIG. 2A (e.g., an option in embodiments is for the first and second sources to share a common vessel before being fed to line 60, where the level of HO in that vessel of the two sources is adjusted by the HO in the feed to that vessel, or another option is to adjust the available feed flow rate depending on the given HO content of the source, such as in aqueous urea or aqueous ammonia in that vessel, as an alternative way to adjust the hydrolysis level in the flue gas entering the catalytic reactor).

[0136] FIG. 2B illustrates the dashed-dotted area of ​​FIG. 2A in the context of a particular dual or combination source type for the first and second sources (generally referred to as source 46B), which in this case, for example, is aqueous urea or aqueous ammonia, such that a percentage of HO essentially forms part of dual source 46B and is injected into the flue gas stream via injection location 61 by suitable aqueous urea or aqueous ammonia injection means, such as any one or any combination of the ammonia injection means (such as an ammonia injection grid) described herein.

[0137] Thus, when feeding aqueous urea or aqueous ammonia (or other water-based SCR reductant), a hydrolysis source is provided in the aqueous urea or aqueous ammonia feed, and the control unit takes the hydrolysis source into account when determining the best ratio suitable for removing HCN and preferably other contaminants as described above. Additionally, a second HO source (generally a third source) 54 may be maintained for situations where the typical HO percentage in aqueous urea is deemed insufficient for the desired level of hydrolysis in reactor 38. For example, in a standard aqueous urea having a urea % level such as 32.5 percent, the relative HO / NH ratio can be increased by feeding additional third source 54 (shown as feed valving unit 52, but alternative embodiments include a feed to a tank represented by source 46 for dilution of its contents, or a separate line of HO injection into the reactor itself or upstream of inlet line 34).

[0138] As noted above, dual source 46B is preferably a source essentially comprising HO. Thus, in addition to aqueous urea, sources may also feature aqueous ammonium formate or aqueous ammonia, each of which can be manipulated by varying the level of solvent (water) in each to provide a similar function as described above for aqueous urea (and adjusting the percentage of HO therein). The level of hydrolysis can also be manipulated solely by adjusting the feed from dual source 46B, for example, if variations in the associated ammonia or ammonia precursor can be tolerated per control unit. In alternative embodiments where mixing times are appropriate, either of the aforementioned sources 46B can be provided in dry form, with source 54 being used to provide the desired solvent level upon injection (in which case source 54 represents a second source rather than a third source). Also, in FIG. 2B, control unit 124 is only partially shown (or features sub-control units) and is referred to as control unit 124S.

[0139] FIG. 2C also illustrates the dashed-dotted region of FIG. 2A, featuring a system lacking the added source 54 and instead relying solely on dual source 46B. This includes the aforementioned solvents, such as solvents with HO, which can be supplied with a pre-designed HO content to achieve the desired flue stream addition. Rather than adjusting the solvent level, the supply rate may be adjusted to a lower or higher rate as determined by the control unit (using a sub-control or partial control unit as shown in FIG. 2C). In the above implementation, the same rate adjustments may be made to source supplies 46 and 54 on one side or the other.

[0140] The catalyst system 24 of the present invention (and embodiments thereof, such as catalyst systems 24A, 24B, and 24C) is capable of reducing the mentioned pollutants HCN, and preferably also VOCs, NO, in the flue gas effluent from the main distillation column of an FCC unit. xIn other words, the catalyst system described herein is the only means for removing the aforementioned contaminants exiting the main distillation column of the FCC unit (at least HCN, or NO, positioned between the main distillation column and the atmosphere). x and HCN, or HCN, NO x and CO) by contacting the flue gas with one of the catalytic reactors of the present invention (where oxidation of CO and VOCs is involved and not done by separate means, it is characterized as a DFC).

[0141] FIG. 4 illustrates several alternative embodiments of the present invention having, in addition to any one of the catalytic reactors 38 described above, associated catalytic reactors focusing on one or more additional alternative functions either upstream and / or downstream of the catalytic reactors 38 described above of the present invention, highlighting the catalytic units sequentially located downstream of the main distillation column (as noted above, the more upstream locations of the overall FCC unit, and thus the SO 2 stoichiometric catalytic converters associated with some FCC units, often upstream of the main distillation column). x(Various pre-distillation pollutant removal units, such as scrubbers and cyclone catalytic systems, can be involved in the FCC unit.) In this regard, FIG. 4 illustrates an example of a multiple catalyst group (intended for different functions) that includes one or more catalytic devices in the group other than the HCN reduction catalytic reactor featured in the present invention. Thus, in FIG. 4, a catalyst assembly CA can be seen that includes catalytic reactor 38M (intended as a generic designation for any one of the aforementioned reactors 38 having any one of the catalytic device configurations described and / or illustrated above). The one or more additional catalytic devices are represented by one or the other (or both) of catalytic units 368 and 468 in FIG. 4, which are preferably catalytic reactors focused on a different catalyst than reactor 38M (e.g., units 368 and 468 are not focused on HCN reduction control). Thus, either or both of catalytic reactors 368 and 468 can be placed in the flue gas line in combination with reactor 38M. For example, the addition of an additional active oxidation catalyst 468 downstream of reactor 38M with non-SCR functionality is shown where additional treatment is needed according to the desired HCN removal level (such as additional oxidation catalyst to deal with NH3 slip away from reactor 38M). x It may feature an upstream reactor 368, such as a catalytic reactor for level regulation, designed to treat the flue gas to better form its chemical constituents upon entering reactor 38M.

[0142] Thus, in FIG. 4, additional upstream catalytic reactors 368 and / or downstream reactors 468 are shown in dashed lines (to represent the optional nature of that situation), which may also include additional SCR reactors, catalyzed particulate filters, SO 4 filters, etc. xThe catalytic reactor 38M may take a variety of forms, including catalysts for the removal of nitrogen oxides, stand-alone oxidation catalysts, adsorption catalysts (nitrogen oxide storage and release catalysts), and other alternative forms such as other catalytic means that provide the desired function in combination with the catalytic reactor 38M. Also, where applicable (such as at least some alternatively functioning catalysts may not require additional materials such as reducing agents to operate), any additional catalytic means for use in the catalytic reactor 38M, such as those depicted in Figures 2A-2C, may utilize a common source supply, or may rely on an independent source, preferably featuring sensors and associated control units, or may not be relied on at all if no upstream feed, such as reducing agents, is involved and only flue gas contact is involved.

[0143] The method of the present invention involves the reduction of HCN in flue gases emitted from an FCC unit by passing the off-gas through any one of the catalyst systems described above, preferably with associated sensor monitoring and control, which catalyst system is preferably used not only for the reduction of HCN but also for the production of NO. x , and may also be configured for the simultaneous removal of additional contaminants such as CO and any one or any group of other hydrocarbon contaminants (HCN and NO x (The simultaneous removal of urea and ammonia is exemplary). When featuring sensing and / or control means, the catalyst system can be operated to regulate the supply of SCR reductant, such as the aforementioned ammonia source, by adjusting the flow rate, for example, with a flow controller and / or valving. Additionally or alternatively, if available, a second source, such as a hydrolysis promotion source (comprising ammonia or ammonia precursor and water in a common reservoir), or a source dilution means, such as the aforementioned water source 54, can be regulated (again, by adjusting the flow rate, for example, with a flow controller and / or valving). This involves diluting the aqueous first source and adding dilution water to the reservoir tank of the urea or aqueous ammonia source, thereby providing a more dilute version of the reductant as typically supplied in the market.

[0144] Exemplary embodiments of the systems, methods, and devices are described in detail above. The systems, methods, and devices are not limited to the specific embodiments described herein; rather, the operations of the methods and / or components of the systems and / or devices can be utilized independently and separately from other operations and / or components described herein. Furthermore, the described operations and / or components may also be defined in or used in combination with other systems, methods, and / or devices, and are not limited to practice solely with the systems, methods, and storage media as described herein.

[0145] When introducing elements of aspects of the invention or embodiments thereof, the articles "a," "an," "the," and "said" are intended to mean that there are one or more elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0146] In this disclosure, value points are also intended to include all intermediate points (and all subranges within larger specified ranges) in value in common exponent units, such as a range of 1 to 10 including subranges derived therein, such as 2, 3, 4 to 9, and 3 to 5, or a range of 1.0 to 10.0 including all intermediate points 1.1, 1.2, 1.3 to 9.9 (and all subranges within larger specified ranges, such as 1.3 to 1.7). [Explanation of symbols]

[0147] 20 FCC unit assembly 22 FCC units 24 Catalyst Systems 24A Catalyst System 24B Catalyst System 24C Catalyst System 26 FCC unit reactor 28 lines 30 Main distillation (or fractionation) column 32 Bottom conduit 34 Conduit 35 Outlet conduit 36 Atmosphere 38 Catalytic Reactor 38A Catalytic Reactor 38B Catalytic Reactor 38C Catalytic Reactor 38D Catalytic Reactor 38E Catalytic Reactor 38F(a) Catalytic Reactor 38F(b) Catalytic reactor 38F(c) Catalytic Reactor 38G Catalytic Reactor 38H catalytic reactor 38I Catalytic Reactor 38J Catalytic Reactor 38K Catalytic Reactor 38L catalytic reactor 38M catalytic reactor 40 Inlet end 42 Outlet end 46 Reducing Agent Source 46B Dual Source 48 Supply Line 50 Flow Controller 52 Valve unit 54 Secondary (e.g., water for hydrolysis) source 56 Supply Line 58 Flow Controller 60 Supply Line 61 Injection position 62 Sensor Device 64 Sensor Device 66 Sensor Device 68 Housing 70 Catalytic Converter 70A Catalyst Article 72 Catalytic Converter 72A Catalyst articles 73 Catalytic Converter 74 Catalyst articles 76 Catalyst articles 77 Catalytic Converter 78 SCRart 80 DFC 81 Catalytic converter 81G catalytic converter 82A DFC 82B DFC 83 Catalyst articles 84(a) Catalyst devices 84(b) Catalyst devices 85A SCRart type catalytic converter 85B SCRart type catalytic article 86 Catalyst articles 87 Catalytic Converter 88 Catalyst articles 89 Catalyst articles 90 Catalytic Converter 91 Catalyst articles 92 Catalyst articles 93 Catalytic Converter 94 Catalyst articles 95 Catalyst articles 96 Catalytic Converter 97 Catalyst articles 98 Catalyst articles 99 Catalytic Converter 100 Spacing or bridging conduits 101 Upstream catalytic articles 102 Downstream catalytic articles 103 Housing 104 Housing 105 Housing 106 Supply Line 108 Supply Line 110 Catalytic converter 112 Spacing or bridging conduits 114 Upstream catalytic articles 116 Downstream catalytic articles 118 Housing 120 Housing 122 Housing 124 Control Unit 124S control unit 368 Catalytic Converter 468 Catalytic Converter CA Catalyst Assembly L Length from upstream to downstream (from inlet to outlet) L1 Housing (or casing) length L2 Housing (or casing) length

Claims

1. 1. An assembly comprising: HCN and NO ｘ a fluid catalytic cracking (FCC) unit generating a flue gas comprising: HCN and NO in the flue gas ｘ a catalyst system comprising a catalytic device disposed along the flue gas for removing a first source comprising ammonia or an ammonia precursor; H ２ a second source comprising O; and an injector for supplying one or each of the first and second sources into the flue gas upstream of the one of the one or more catalyst articles.

2. The assembly of claim 1 , wherein the one or more catalytic articles of the catalytic device include each of a DFC and an SCRart.

3. 3. The assembly of claim 2, wherein the catalytic device includes at least three catalytic articles such that the catalytic device is characterized by at least two DFCs combined with one SCRart or at least two SCRarts combined with one DFC.

4. 4. The assembly of claim 3, wherein the catalytic device comprises two DFCs and one SCRart in an arrangement from upstream to downstream of DFC / SCRart / DFC or SCRart / DFC / DFC or DFC / DFC / SCRart.

5. 4. The assembly of claim 3, wherein the catalytic device comprises two SCRarts and one DFC in an arrangement of SCRart / SCRart / DFC or SCRart / DFC / SCRart or DFC / SCRart / SCRart.

6. 6. The assembly of any one of claims 1 to 5, wherein one of the one or more catalytic articles of the catalytic device comprises vanadium.

7. 7. An assembly according to any one of claims 1 to 6, further comprising means for determining the level of HCN either directly or indirectly relative to the level of HCN passing downstream of the catalytic device.

8. 8. The assembly of claim 7, wherein the means for determining comprises a sensor or sampler for directly determining the level of HCN passing downstream of the catalytic device.

9. 9. The assembly of claim 8, further comprising a control unit, wherein the means for determining includes an indirect determination of the level of HCN comprising a CO sensor in communication with the control unit for extrapolation determination of the amount of level of HCN by the control unit.

10. 10. The assembly of claim 1, further comprising a container, wherein the first and second sources are commonly stored within the container, and a first supply line extending from the container to the injector for injecting each of the first and second sources together into the flue gas flowing to the injector.

11. The first and second sources are urea and H mixed with urea or aqueous ammonia in the container. ２ 11. The assembly of claim 10, wherein

12. 12. The assembly of any one of claims 1 to 11, further comprising a control unit, wherein the first and second sources are fed to a distribution system comprising a valving system in communication with the first and second sources, one or more feed lines of the distribution system supply the first and second sources to the injection devices for supplying one or both of the first and second sources to the injection devices for injection into the flue gas passing towards the catalytic device, the control unit being in communication with sensing means for monitoring one or more properties of the flue gas and the distribution system for adjusting the relative percentages of the first and second sources.

13. 15. The assembly of claim 14, wherein the control unit is configured to adjust the flow from the second source based on one or more sensed characteristics of the flue gas to provide a variable range of water vapor volume fraction in the flue gas flowing to the catalytic device between 0% and 15% by volume based on a desired level of hydrolysis determined by the control unit.

14. A method of operating an assembly according to any one of claims 1 to 13, comprising the steps of: generating the flue gas in the fluid catalytic cracking (FCC) unit; HCN and NO ｘ and passing said flue gas through said catalytic device to remove

15. 15. A method of operating the assembly of claim 14, further comprising sensing the flue gas to determine or estimate the level of HCN downstream of the catalytic device.

16. 1. A method for removing HCN from a flue gas stream, comprising: The flue gas is passed through a catalytic system including a catalytic device disposed along the flue gas to remove HCN and NO in the flue gas. ｘ wherein the catalytic device has one or more catalyst articles, one of the one or more catalyst articles being a platinum group metal material (PGM)-free SCR catalyst article (SCRart) or an SCR catalyst article including PGM to provide a dual function SCR catalyst article (DFC); and monitoring the level of HCN in the flue gas exiting the catalyst system.

17. 17. The method of claim 16, wherein the flue gas is generated by a fluid catalytic cracking (FCC) unit.

18. 1. An assembly comprising: HCN and NO ｘ a fluid catalytic cracking (FCC) unit generating a flue gas comprising: a control unit; HCN and NO in the flue gas ｘ a catalytic device disposed along said flue gas for removing PGM (preferably palladium), oxides of vanadium and titanium, preferably oxides of tungsten, oxides of molybdenum and silica (preferably tungsten alone or tungsten with silica, in the latter case mainly SiO ２ Doped TiO ２ a catalytic device comprising at least one dual-function catalyst article (DFC) comprising a substrate that is a corrugated substrate supporting a catalytic composition further comprising at least one or any combination of: a sensor device for directly or indirectly monitoring the level of HCN in the flue gas exiting the catalytic device.

19. a first source having ammonia or an ammonia precursor material; ２ 20. The assembly of claim 18, further comprising: a second source comprising O; supply means for supplying one or both of a first source material and a second source material to the flue gas upstream of the catalytic device; and a control unit configured to adjust the supply means to vary the amount of the first source and the second source material supplied to the flue gas.

20. 20. The assembly of claim 18 or 19, further comprising a PGM-free second SCR catalyst article (SCRart) within the catalytic device.

21. 21. The assembly according to any one of claims 18 to 20, characterized in that the catalytic device comprises at least three catalytic articles, a first catalytic article of the at least three catalytic articles being an SCR catalytic article (SCRart) that does not contain platinum group metal materials (PGM), and a second catalytic article of the at least three catalytic articles being the dual function catalytic article (DFC), the at least three catalytic articles being at least two DFCs combined with one SCRart or at least two SCRarts combined with one DFC.

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