Hydrogen generation in high temperature countercurrent reactors

Abstract

Systems and methods are provided for reforming in such a manner that a flow providing heat for an endothermic reforming reaction is countercurrent to a flow of the reforming reaction. Although the flow is countercurrent, the systems and methods also allow the heating profile of the reactor to have a temperature peak in the middle of the reactor rather than at the ends of the reactor. Moving temperature peaks to the middle allows for improved heat utilization and recovery during operation of the reactor.

Description

Technical Field

[0001] Systems and methods are provided for generating hydrogen in a high temperature countercurrent reactor. Background Art

[0002] Steam reforming is a common technology for converting methane or other hydrocarbons into hydrogen and carbon oxides. One option for steam reforming is to use a countercurrent configuration with discontinuous or separated flows. One stream corresponds to the stream that is steam reformed. The second stream corresponds to a heat transfer stream that is kept separate from the volume that is steam reformed. These streams are arranged in a countercurrent manner so that the hottest part of the heat transfer stream at one end of the reactor corresponds to the position that provides the highest reforming temperature. Due to the endothermic and reversible nature of the reforming reaction, it is beneficial to have the highest temperature for reforming at the end of the reactor. Higher temperatures are conducive to bringing the reforming reaction closer to completion.

[0003] US Patent 8,168,131 describes a low pressure drop reforming reactor. The reforming reactor is equivalent to a countercurrent reactor. In order to allow at least partial recovery of heat from the reformed product, the reformed product is mixed with a heating stream passing in countercurrent around the reforming reaction volume after the product leaves the reforming reaction volume.

[0004] US Patent 7,918,906 describes a steam reforming reactor with a linear countercurrent heat exchanger. The external volume of the reactor is equivalent to a boiling water heat exchanger. Heat is provided to the reactor by burning a first portion of the reactant stream. The partially burned reactant stream is then used as a feed for reforming.

[0005] US Patent 7,094,363 describes a process for producing synthesis gas.

[0006] US Patent 7,744,664 describes a compact counter-flow fuel reformer.

[0007] U.S. Patent 7,815,873 and U.S. Patent 8,754,276 provide examples of various endothermic processes using a countercurrent reactor in a cyclic reaction environment. A countercurrent reactor is an example of a type of reactor that is advantageous for use in a process with cyclic reaction conditions. For example, due to the endothermic nature of the reforming reaction, it is necessary to continuously introduce additional heat into the reforming reaction environment on a consistent basis. A countercurrent reactor can provide an effective method for introducing heat into the reaction environment. After a portion of the reaction cycle is used for reforming or another endothermic reaction, the second portion of the reaction cycle can be used for combustion or another exothermic reaction to add heat to the reaction environment in preparation for the next reforming step.

[0008] U.S. Patent Application Publication 2020 / 0030778 describes a monolith structure for hydrocarbon reforming, wherein the monolith structure includes a mixture of one or more doped metal oxides and one or more structural oxides. The selection of the doped metal and the structural oxide is based on the relative Gibbs free energy values ​​of the doped metal oxide and the structural oxide. NiO and Al2O3 are described as examples of suitable combinations of doped metal oxides and structural oxides that form the monolith structure. The monolith structure can be used in a circulating flow reactor.

[0009] U.S. Patent Application Publication No. 2022 / 0112082 describes a catalyst system for reforming in a circulating flow reactor. Monoliths for supporting the catalyst system are also described. Some examples of monoliths are described, the composition of which corresponds to 93 wt%-95 wt% Al2O3, 4.0 wt%-5.0 wt% SiO2, and optionally 1.0 wt%-2.0 wt% MgO, TiO2, and / or Na2O. It is noteworthy that the channels in these monoliths correspond to square channels. Summary of the invention

[0010] In one aspect, a method for performing countercurrent reforming is provided. The method includes delivering fuel to a fuel flow path in a recuperation zone of a reactor volume and delivering an oxygen-containing gas to an oxidant flow path in a recuperation zone of the reactor volume. The method also includes delivering a reforming input stream containing at least one hydrocarbon to a plurality of reforming flow channels in a reforming zone of the reactor volume. The flow direction of the reforming input stream may be substantially countercurrent to the flow direction of at least one of the fuel and the oxygen-containing gas. The reforming channel may include a reforming catalyst in the reforming zone. The method also includes mixing the fuel and the oxygen-containing gas in one or more heating flow channels in a mixing zone of the reactor volume to form a fuel mixture. The mixing zone may be adjacent to the recuperation zone, and the opposite side of the mixing zone is adjacent to the reforming zone. The method also includes reacting the mixture in one or more heating flow channels in at least one of the mixing zone and the reforming zone to produce a heat and oxidation product stream. The one or more heating flow channels may be arranged around the plurality of reforming flow channels. The method also includes reforming at least a portion of the at least one hydrocarbon in the reforming channel under reforming conditions to form a reformed product stream. The method also includes discharging the reformed product stream from the heat exchange zone. In addition, the method includes discharging an oxidation product stream from the reforming zone.

[0011] In another aspect, a countercurrent reforming reactor is provided. The reactor includes a reactor volume. The reactor volume may include a heat exchange zone, one or more mixing elements in a mixing zone, a reforming zone, a plurality of first flow channels, and one or more second flow channels. At least a portion of the plurality of first flow channels may be located in the reforming zone. At least a portion of the plurality of first flow channels may include a reforming catalyst on one or more surfaces of the plurality of first flow channels in the reforming zone. The mixing zone may be adjacent to the heat exchange zone, and the opposite side of the mixing zone is adjacent to the reforming zone. One or more second flow channels may be arranged around the plurality of first flow channels. The heat exchange zone may include at least an oxidant flow path and a fuel flow path. At least one of the fuel flow path and the oxidant flow path may provide fluid communication between the end of the heat exchange zone and the mixing zone, without providing fluid communication between the oxidant flow path and the fuel flow path in the heat exchange zone.

[0012] BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 An example of a side view of the internal element stack of a countercurrent reforming reactor is shown.

[0014] Figure 2 A cross-sectional view showing an exemplary configuration of a monolith within a countercurrent reforming reactor is shown.

[0015] Figure 3 An example of a temperature profile for a countercurrent reforming reactor is shown. DETAILED DESCRIPTION

[0016] All numerical values ​​in this detailed description and claims are modified by "about" or "approximately" the indicated value, and take into account experimental error and variations that would be expected by a person skilled in the art.

[0017] Overview

[0018] In various aspects, systems and methods are provided for performing reforming in a manner in which the flow providing heat for the endothermic reforming reaction is countercurrent to the flow of the reforming reaction. Despite the countercurrent flow, the systems and methods also allow the heating profile of the reactor to have a temperature peak toward the middle of the reactor, rather than at the ends of the reactor. This shift of the temperature peak toward the middle allows for improved heat utilization and recovery during reactor operation.

[0019] Typically, a countercurrent reactor can be used for steam reforming. In a conventional countercurrent reactor, a first volume of the reactor is used for heating the stream, while another volume (typically contained within the first volume) corresponds to the volume in which steam reforming occurs. In this conventional configuration, the volume is arranged so that the heating stream does not enter the second volume in which the reforming reaction occurs. This avoids any problems caused by dilution and / or contamination of the steam reforming reactants before the reforming reaction is completed.

[0020] One of the difficulties with conventional methods of steam reforming using countercurrent is that the highest temperature in the reactor is at the end of the reactor. This is due to the heating stream being heated before being introduced into the countercurrent environment. Therefore, the heating stream is at its highest temperature when it first enters the countercurrent environment. In order to take advantage of this highest temperature, catalyst is included all the way to the end of the reactor environment. However, this reduces or minimizes the opportunity to exchange heat from the reformate.

[0021] In contrast to this conventional design, in various aspects, a countercurrent reactor configuration is provided, wherein the reforming zone is located in the middle of the reactor so that the end of the reactor is lower than the peak temperature occurring between the ends of the reactor. This temperature distribution is achieved in part by burning in the heating flow volume of the reactor, wherein the combustion is delayed so that the combustion occurs at a place away from the end of the reactor where the combustion input stream is introduced. By delaying the combustion until the combustion input stream arrives inside the heating flow volume, improved heat utilization in the reactor can be achieved. For example, after the reforming stream in the reactor volume passes through the high temperature zone, heat exchange can be performed between the reactor volume and the heating flow volume. This allows the combustion input stream to be preheated before combustion, and thus allows a portion of the combustion heat to be recovered during the process, rather than simply exhausting any heat that is not used for the endothermic reforming reaction.

[0022] Various types of configurations can be used to achieve countercurrent steam reforming as described herein. In some aspects, the countercurrent reactor can correspond to a reactor housing comprising multiple monoliths (e.g., ceramic monoliths). The monolith can include a channel or a unit. In this type of aspect, a portion of the channel (or unit) corresponds to a reforming flow channel for carrying reforming reactants and products, and a second portion of the channel corresponds to a heating flow channel for carrying a combustion input stream and combustion products. The channel can be configured so that at multiple locations within the monolith, multiple heating flow channels are arranged around one or more reforming flow channels. This allows heat transfer from a heating flow channel to a reforming flow channel or from a reforming flow channel to a heating flow channel.

[0023] In other aspects, a shell and tube heat exchanger configuration can be used. In this type of configuration, the shell volume can correspond to the heating flow channel. One or more tubes used as the reforming flow channel are at least partially contained within the heating flow channel. In other words, the shell volume is arranged around the tube flow channel for reforming.

[0024] In some aspects, there is substantially no fluid communication between the flow channel for reforming and the flow channel for heating. In these aspects, this allows the two types of flows to remain separated so that the reformed products do not mix with the combustion products from the heating flow. In other aspects, mixing of the reformed products with the combustion input flow and / or the combustion output flow can occur after the reformed products leave the reformed flow channel.

[0025] In some aspects, another advantage of the countercurrent reforming reactor can be the ability to perform partial oxidation in the heating flow channels. Using partial oxidation in the heating flow channels can reduce the amount of heat generated per fuel molecule, thereby requiring more fuel to provide heat for the reforming reaction in the reforming flow channels. However, by performing partial oxidation, the heating flow exhaust can also include at least CO in addition to H2O and CO2. The presence of CO (optionally H2) in the heating flow exhaust after partial oxidation means that a portion of the partially oxidized exhaust can be recovered as syngas value, optionally after exposure to a catalyst of some type having water gas shift activity.

[0026] In some aspects, another advantage of the countercurrent reforming reactor can be that a limited amount of additional steam reforming can be performed in the heating flow channel. In this respect, a limited amount of reforming catalyst can be included in the heating flow channel at a position downstream of the fuel and oxygen mixing position, or upstream of the heating flow leaving the reactor. This can avoid the highest temperature when the partial combustion initially occurs, while still being in a sufficiently high temperature zone to maintain a more favorable H2 to CO ratio in the resulting reformed product. Since the heating flow channel also needs to provide heat for the reaction in the reforming flow channel, the amount of reforming that occurs in the heating flow channel is limited relative to the total flow rate. However, this configuration can provide a heating flow exhaust with an improved H2 to CO ratio relative to conventional partial oxidation output flow.

[0027] Flow channel example - monolithic

[0028] One type of configuration for performing countercurrent reforming is to use one or more monoliths to define a plurality of first reforming flow channels and a plurality of second heating flow channels.Any convenient number of monoliths may be placed in the reactor to provide the flow channels.

[0029] The reforming flow channel may correspond to a channel in the monolith, the channel comprising a reforming catalyst deposited on at least a portion of the channel surface. Although the entire length of the channel may include a reforming catalyst, in some aspects, the reforming catalyst may be omitted from the portion of the channel end closest to the recuperator. This allows the reforming catalyst to be present at and / or near the position with the highest temperature in the reforming flow channel, but the last portion of the reforming flow channel can only be used for heat transfer. Since reforming is an equilibrium process, the last portion of the reforming flow channel that does not include a reforming catalyst can avoid the transfer of reforming products back to the reactants because the reverse (methanation) reaction becomes more favorable at lower temperatures.

[0030] The heating flow channel may correspond to a channel in the monolith that does not include a catalyst. However, the heating flow channel may be configured so that combustion of the fuel introduced into the heating flow channel does not occur until the fuel reaches a target location away from the heat exchanger end of the reactor. This can be achieved, for example, by first introducing the fuel and oxidant (e.g., air or another O2-containing gas stream) into separate channels and then mixing the fuel and oxidant using a mixer at a downstream location.

[0031] Figure 1 A side view showing how monoliths can be stacked in combination with other elements to provide reactor internals for a countercurrent reforming reactor. Figure 1 In the embodiment shown, each element in the stack may represent a single element filling the entire reactor cross-section, or each element may represent multiple parallel elements.

[0032] exist Figure 1 In the side view shown, a stack of reactor internal elements is shown. The stack is shown as a horizontal configuration, but a vertical configuration may also be used, such as a configuration in which the heat exchanger element 110 and the mixer element 120 are located at the top of the vertical stack. In this discussion, the end including the heat exchanger element 110 may be referred to as the recuperation side or heat exchange end of the reactor. The end including the monolith 130 may be referred to as the reforming side or reforming end of the reactor.

[0033] During operation, heat exchanger element 110 corresponds to the input flow side of the stack for combustion / heating flow and the output flow side of the stack for reforming flow. The opposite end (starting from monolith 130) corresponds to the output flow side of the stack for combustion / heating flow and the input flow side of the stack for reforming flow.

[0034] exist Figure 1 , the monolith 130 corresponds to a monolith including a reforming flow channel and a heating flow channel. The reforming flow channel in the monolith 130 includes a reforming catalyst. The heating flow channel does not include a catalyst. During operation, combustion is performed in the heating flow channel to add heat to the monolith 130. The heat is transferred to the reforming flow channel to provide heat for the endothermic reforming reaction.

[0035] The heat exchanger element 110 also includes channels, but the operation of the channels is slightly different. Some flow channels in the reflow element 110 correspond to channels for receiving flows from the reforming channels. Optionally, the reforming flow channel in the reflower can be the same as the reforming flow channel in the reforming zone, so that the reforming flow channel is continuous from the reforming end of the reactor to the reflow end of the reactor. However, the part of the reforming flow channel in the reflow element 110 does not include a reforming catalyst. On the contrary, in the heat exchanger, the output flow from the reforming reaction is actually higher than the temperature of the input flow for the combustion reaction. Therefore, heat is transferred from the reforming output flow in the reforming flow channel to the input flow for combustion. This allows the input flow for combustion to be preheated before the combustion reaction is performed. It is worth noting that combustion does not usually occur in the heat exchanger element 110. On the contrary, combustion is delayed until the combustion input flow reaches the heating flow channel in the integral part 130. For example, this combustion delay can be achieved by using a portion of the flow channel to carry fuel for combustion while using another portion of the flow channel to carry oxidant. The fuel and oxidant may then mix in the heated flow channels in the monolith 130 .

[0036] The mixer element 120 helps mix the fuel and oxidant before the combustion input stream passes through the heating flow channels in the monolith 130. Any convenient type of mixer element may be used that can help distribute the fuel and oxidant substantially evenly into the heating flow channels in the monolith 130. By mixing the fuel and oxidant at or near the outlet of the mixer element 120, combustion can be initiated at or near the beginning of the combustion input stream entering the heating flow channels of the monolith 130.

[0037] Figure 1 The stack of internal reactor elements shown in may be housed in any convenient type of reactor. One suitable type of reactor housing may be a housing for a countercurrent reactor, such as the type described in US Pat. No. 7,815,873 and US Pat. No. 8,754,276.

[0038] Figure 2 An example of a hexagonal monolith configuration is shown, where a separate monolith contains reforming flow channels and heating flow channels. This configuration example illustrates how monoliths can be combined together to provide a monolith with heating flow channels arranged around a monolith containing reforming flow channels. Figure 2 The configuration in represents a cross section perpendicular to the channel axis. Figure 2In the embodiment, monolith 210 corresponds to the monolith containing the reforming flow channel. Monolith 220 corresponds to the monolith containing the heating flow channel. It is worth noting that due to the relative amount of heat generated by combustion and the heat consumed by reforming, the flow rate of the input flow for combustion is often greater than the flow rate of the input flow for reforming. One way to accommodate the higher flow rate of the combustion input flow is to use a greater number of heating flow channels, such as Figure 2 Another option is to have a similar number of monoliths for heating flow channels and reforming flow channels, but with a higher flow rate in the heating flow channels. It is worth noting that, for convenience, monoliths with heating flow channels or reforming flow channels are described. In other aspects, the heating flow channels can be arranged around the reforming flow channels for flow channels within a single monolith.

[0039] The flows in the heating flow channel and the reforming flow channel can be kept separate in any convenient way. One option is to use a manifold and / or other fluid connectors to keep the flow path of the reforming flow channel separated from the heating flow channel. In addition or alternatively, each monolith or group of monoliths can be separated by a continuous ceramic barrier to reduce cross leakage, or interlocking monoliths can be used to minimize cross leakage. At the heat exchanger end where the combustion input flow enters the stack, a distribution system can be used to input the combustion input flow to the appropriate monolith / heating flow channel, while the reforming monolith / reforming flow channel is invisible to these combustion input flows. An example of how to do this is to construct the top layer of the monolith so that the connecting lateral channels (not shown) collect the combustion gas flow through the appropriate outlet / inlet. This configuration allows relatively close contact and rapid heat transfer between the reforming flow and the heating flow while still reducing cross leakage.

[0040] One of the purposes of using a monolith or another supporting structure in a reforming environment is to increase the available surface area for accommodating the deposited catalyst / catalyst system. In order to achieve this, some monoliths correspond to structures with a large number of cells or channels that allow gas to flow through the monolith. Since each individual cell provides a surface area for catalyst deposition, a large number of cells or channels per unit area can greatly increase the available surface area of ​​the catalyst. Similarly, a large number of channels can promote a higher volumetric flow rate of the combustion gas, thereby providing heat for the endothermic reforming reaction. Such monoliths can generally be referred to as honeycomb monoliths. It is worth noting that the terms "cell" and "channel" can be used interchangeably to refer to the channel passing through the monolith.

[0041] The monolith can be made of any convenient material that can withstand high temperature environments while being substantially non-reactive in the presence of reforming input streams and combustion input streams. One option is to use a ceramic monolith, such as a monolith made of alumina or an alumina alloy. Such monoliths have been used in, for example, countercurrent reactors, where the monolith is exposed to alternating flows of reducing gas and oxidizing gas at high temperatures. However, in countercurrent reforming applications, any given portion of the monolith will be exposed to either the oxidizing flow or the reforming flow, so durability when exposed to alternating combinations of flows is less important. It is further noted that since both the reforming flow and the heating flow are continuous, the thermal capacity of the monolith material is less important, as long as the monolith material has suitable heat transfer properties. This can expand the range of choices for the monolith material. In some aspects, monoliths with improved heat transfer properties can be used, such as metal monoliths, ceramic monoliths with metal coatings, or monoliths comprising metal-doped alumina, such as copper-doped or titanium-doped alumina.

[0042] For ceramic monoliths and / or monoliths including ceramic portions, in various aspects, monoliths or other structures for providing flow channels for countercurrent reforming systems can be prepared by manufacturing techniques, such as, but not limited to, conventional ceramic powder manufacturing and processing techniques, such as mixing, grinding, degassing, kneading, pressing, extrusion, casting, drying, calcining and sintering. The starting materials can correspond to suitable ceramic powders and organic binder powders in suitable volume ratios. Certain process steps can be controlled or adjusted to obtain the desired particle size and porosity ranges and performance characteristics, such as by adding various manufacturing, performance adjustment and processing additives and reagents generally known in the art. For example, two or more types of oxide powders can be mixed in the presence of an organic binder and one or more suitable solvents for a time sufficient to allow the powders to be fully dispersed in each other. As another example, the precursors of the oxides present in the monolith can be dissolved in water in a desired proportion, spray dried and calcined to form a mixed powder. Such precursors include, but are not limited to, chlorides, sulfates, nitrates and mixtures thereof. The calcined powders can be further mixed in the presence of an organic binder and a suitable solvent to form a mixed "dough". The mixed "dough" material can then be placed into a mold or form, extruded, dried or otherwise formed into a desired shape. The resulting "green body" can then be sintered at a temperature of about 1200°C to 1700°C for at least ten minutes, such as 10 minutes to 10 hours, or possibly from 10 minutes to 48 hours or more.

[0043] The sintering operation can be carried out in an oxidizing atmosphere, a reducing atmosphere, or an inert atmosphere, and at ambient pressure or vacuum. For example, the oxidizing atmosphere can be air or oxygen, the inert atmosphere can be argon, and the reducing atmosphere can be hydrogen, CO / CO2, or a H2 / H2O mixture. Thereafter, the sintered body is cooled, typically to ambient conditions. The cooling rate can also be controlled to provide a desired set of grain and pore structures and performance characteristics in a particular component.

[0044] In certain aspects, the monolith may be formed at least in part from alumina. Notably, following the sintering operation, any alumina present in the monolith will be substantially converted to alpha-alumina. The "alpha" phase of alumina is thermodynamically favorable at high temperatures, and the temperatures during sintering are sufficient to substantially convert any other phase of alumina to the "alpha" phase. This is beneficial from a stability perspective because converting the alumina in the monolith to alpha-alumina means that phase changes will not occur during exposure of the monolith to cyclic reforming conditions, where the presence of alternative phases of alumina may promote the formation and / or propagation of cracks.

[0045] Sintered monoliths and / or other formed ceramic structures can have any convenient shape suitable for use as surfaces receiving catalysts or catalyst systems. Examples of monoliths can be extruded honeycomb monoliths. Honeycomb monoliths can be extruded structures comprising many (e.g., multiple, meaning more than one) small gas flow channels or conduits, arranged in parallel, with thin walls between gas flow channels or conduits. Small reactors can include a single monolith, while larger reactors can include multiple monoliths, and larger reactors can be substantially filled with arrangements of many honeycomb monoliths. Each monolith can be formed by extruding monolithic blocks having a cross section of a shape (e.g., square, triangle or hexagon) and stacking these blocks two-dimensionally or three-dimensionally above, behind and beside each other. Monoliths may be attractive as reactor internal structures because they provide high heat transfer capabilities and minimal pressure drop.

[0046] In some aspects, the density measured by the Archimedean method well known to those skilled in the art can be 3.40 g / cm3 or higher, or 3.50 g / cm3 or higher, such as up to 4.00 g / cm3 or possibly higher. In some aspects, the porosity can be almost completely closed within the honeycomb monolith wall, and the porosity is 10% or less, or 8.0% or less, such as as low as 1.0% or possibly less.

[0047] In some aspects, the honeycomb monolith is characterized by having an open frontal area (or geometric void volume) between 30% and 70%, or 30% and 60%, or 40% and 70%, or 40% and 60%, or 45% and 55%. Additionally or alternatively, the monolith can have a tube density between 50 cells per square inch (CPSI) and 900 cells per square inch, or 50 to 600, or 300 to 900, or 300 to 600, or 350 to 550. This roughly corresponds to 7 to 140 cells per square centimeter, or 45 to 140, or 7 to 95, or 45 to 95, or 55 to 85. In some aspects, this type of cell density roughly corresponds to cells or channels whose diameter / characteristic cell side length is only a few millimeters, such as about one millimeter. Reactor media components, such as monoliths or alternative bed media, may provide channels comprising packing having an average wetted surface area per unit volume of about 50 ft -1 Up to 3000ft -1 (~0.16km -1 To ~10km -1 ), or 100ft -1 Up to 2500ft -1 (~0.32km -1 To ~8.2km -1 ), or 200ft -1 Up to 2000ft -1 (~0.65km -1 To ~6.5km -1 ) range, based on the volume of the first reactor used to transport the reactants. These relatively high values ​​of surface area per unit volume can help achieve relatively rapid changes in temperature within the reactor.

[0048] In some aspects, the reactor media assembly may also provide a channel including a packing material having a high volumetric heat transfer coefficient (e.g., 0.02 cal / cm 3 s℃ or higher, or 0.05cal / cm 3 s℃ or higher, or 0.10cal / cal / cm 3 s°C or higher); have low flow resistance (low pressure drop); have an operating temperature range consistent with the maximum temperature encountered during regeneration; have high resistance to thermal shock; and / or have a high overall heat capacity (e.g., 0.10 cal / cm 3 s℃ or higher, or 0.20cal / cm 3 s°C or higher). The values ​​quoted are average values ​​based on the reactor volumes used to deliver the reactants.

[0049] In various aspects, a sufficient heat transfer rate can be characterized by a heat transfer parameter ΔTHT of less than 500°C, or less than 100°C, or less than 50°C. As used herein, the parameter ΔTHT is the ratio of the average volumetric heat transfer rate of the bed required for heat exchange to the volumetric heat transfer coefficient hv of the bed. A volumetric heat transfer rate (e.g., cal / cm2) sufficient for heat exchange is 3 sec) can be calculated as the product of the gas flow rate (e.g. g / sec) and the heat capacity of the gas (e.g. cal / g°C) and the desired end-to-end temperature change (excluding any reactions, e.g. °C), which can then be divided by the volume of the reactor (or portion of the reactor) that the gas passes through (e.g. cm 3 The volumetric heat transfer coefficient hv of a bed can usually be calculated as a coefficient based on area (e.g. cal / cm 2 s℃) and heat transfer specific surface area (av, for example cm 2 / cm 3 ), the latter of which is usually called the wetted area of ​​the filler.

[0050] Flow Channel Example - Shell and Tube Configuration

[0051] An alternative to using monoliths is to use a shell and tube configuration. In a shell and tube configuration, one gas stream is contained within the shell and the other gas stream is contained within the tubes. Typically, reforming will occur in the tubes due to their smaller volume. However, if desired, reforming can be performed in the shell with the heating stream in the tubes.

[0052] In this type of alternative configuration, Figure 1 The reactor volume corresponding to the monolith 130 in the shell contains a tube corresponding to the reforming flow channel, and the shell (e.g., the remaining reactor volume) corresponds to the heating flow channel. However, the heat exchanger element 110 and the mixer element 120 are retained. The function of the heat exchanger element 110 can be maintained in any convenient manner. For example, the tube containing the reforming catalyst and the reforming flow in the shell and tube design can extend through the mixer element and the heat exchanger section. The amount of reforming catalyst in the tube section located in the mixing and / or heat exchanger section can be reduced, minimized or eliminated, so that the tubes in the mixing and heat exchanger section are mainly used to transfer heat back to the combustion input gas flow entering. Preferably, there is substantially no catalyst in the reforming flow tube section located in the mixer section and / or heat exchange section of the reactor.

[0053] Combustion input gas can be maintained in the heat exchanger and mixer section respectively by any convenient method. One option is to use a separate pipeline in the recirculator section to carry the oxidant stream, and the fuel stream is introduced into the shell of the recirculator section. In this type of aspect, the reforming stream in the reforming tube may be mainly used to heat the fuel before combustion. Then, the mixer can allow the oxidant stream and the fuel to mix at or near the interface between the mixer element and the shell volume on the opposite side of the mixer element, which corresponds to the position where the reforming catalyst density in the reforming tube begins to decrease, minimize or eliminate. In this way, the temperature curve can be maintained so that the highest temperature in the shell and tube configuration is located at or near the interface between the mixer element and the reforming tube, rather than having the highest temperature at the reactor end.

[0054] To keep the start of combustion toward the middle of the shell, a barrier can be included at or near the mixer so that there are separate shell volumes on either side of the mixer. The mixer can then be configured so that the only path for fuel to flow from the fuel inlet side of the shell to the heated stream exhaust side of the shell is through the mixer. This can aid in the mixing of the fuel and oxidant and prevent the oxidant from flowing back to the end of the shell where the combustion gases are input.

[0055] With regard to tube design, the reforming catalyst may be loaded into the tube in any convenient manner. One option may be to line the interior of the tube with a refractory material, which is then used as a carrier for the reforming catalyst. Another option may be to incorporate a monolith into the tube, such as a monolith as described herein. Metal tubes without refractory linings may also be suitable, as long as the metal tubes are suitable for use in the case of combustion for heating the interior of the housing.

[0056] To facilitate heat transfer into the reformer flow tubes, the reformer flow tubes may have diameters of approximately 1.0 cm to 8.0 cm, or 1.0 cm to 6.0 cm, or 1.0 cm to 4.0 cm, or 2.0 cm to 8.0 cm, or 2.0 cm to 6.0 cm. To the extent that flow tubes are used to combust an input stream (e.g., flow tubes are used to separate oxidant from fuel in the heat exchanger end of the reactor to delay combustion to the middle portion of the reactor), similar tube diameters may be used.

[0057] Catalysts and catalyst systems

[0058] In various aspects, catalysts and / or catalyst systems for reforming hydrocarbons, and methods of using such catalysts and / or catalyst systems are provided. The catalyst and / or catalyst system can be deposited or otherwise coated on a surface or structure (e.g., a monolith) to achieve improved activity and / or structural stability. In this discussion, the catalyst system is defined as comprising at least one catalyst corresponding to one or more catalytic metals (optionally in the form of a metal oxide) and at least one metal oxide support layer. In some aspects, the catalyst and the metal oxide support layer can be coated on the monolith at the same time, for example in the form of a coating on a support. In these aspects, the catalyst can be mixed with the metal oxide support layer. Alternatively, the catalyst and the metal oxide support layer can be deposited in sequence, so that the support layer is deposited first, and then the catalyst is deposited. In some aspects, the metal oxide support layer may correspond to a thermally stable metal oxide support layer, such as a metal oxide support layer that is thermally stable at a temperature of 800° C. to 1600° C. Optionally, before depositing the catalyst system, an intermediate bonding layer may be applied to at least a portion of the monolith or other structure. The catalyst system may be advantageously used in a cyclic reaction environment, such as a countercurrent reactor or other types of reactors that operate using streams in opposite directions and at different times within a reaction cycle. The reaction conditions in a cyclic reaction environment may also experience fluctuations in temperature and / or pressure during the reaction cycle. In yet other aspects, the catalyst may be deposited without using a corresponding metal oxide support layer.

[0059] In some aspects, the catalyst or catalyst system may correspond to one or more catalysts in a single zone. In other aspects, the catalyst or catalyst system may correspond to multiple catalyst zones. Optionally, in these aspects, at least one catalyst zone may include a catalyst different from the catalyst in the second catalyst zone.

[0060] In some aspects, the catalyst system can include a thermally stable metal oxide support layer. The thermally stable metal oxide support layer corresponds to a metal oxide that has thermal phase stability with respect to a structural phase transition at a temperature between 800° C. and 1600° C. In some aspects, such a thermally stable metal oxide support layer can be formed by using a surface area of ​​20 m 2 / g or less of metal oxide powder coated on the surface (e.g., using a coating). For example, the metal oxide powder used to form the thermally stable metal oxide coating may have a surface thickness of 0.5 m 2 / g to 20m 2 / g, or 1.0m 2 / g to 20m 2 / g, or 5.0m 2 / g to 20m 2 / g of surface area. High temperature reforming refers to reforming performed at a reforming temperature of 1000°C or more, or 1100°C or more, or 1200°C or more (e.g., up to 1500°C or possibly more). In various aspects, the catalyst may be annealed at a temperature of 1000°C or more, or 1100°C or more, or 1200°C or more, or 1300°C or more, such as up to 1600°C or possibly more. The temperature may be substantially similar to or greater than the peak temperature to which the catalyst is exposed during the reforming process cycle. An annealing temperature substantially similar to the peak temperature may correspond to an annealing temperature that differs from the peak temperature by 0°C to 50°C.

[0061] As an example of a thermally stable metal oxide support layer, alumina has a variety of phases, including α-Al2O3, γ-Al2O3, and θ-Al2O3. The metal powder of α-Al2O3 can generally have a thickness of 20 m 2 / g or less. In contrast, the γ-Al2O3 phase and the θ-Al2O3 phase have a higher surface area, and the metal powder used for the γ-Al2O3 and / or θ-Al2O3 coating solution will have a surface area greater than 20 m 2 / g surface area. It is traditionally believed that phases such as θ-Al2O3 or γ-Al2O3 are superior as supporting structures for deposited catalysts because the larger surface per gram of θ-Al2O3 or γ-Al2O3 will allow the utilization of more catalyst active sites than α-Al2O3. However, phases such as γ-Al2O3 and θ-Al2O3 are not thermally phase stable at temperatures between 800°C and 1600°C. At such high temperatures, phases such as γ-Al2O3 and θ-Al2O3 will undergo phase transformations to phases of higher stability. For example, at high temperatures, γ-Al2O3 will first transform into Δ-Al2O3 at about 750°C; then Δ-Al2O3 will transform into θ-Al2O3 at about 950°C; then θ-Al2O3 will transform into α-Al2O3 upon further exposure to high temperatures between 1000°C and 1100°C. Therefore, α-Al2O3 is the thermally stable version of Al2O3 at temperatures between 800°C and 1600°C.

[0062] In various aspects, one option for adding a catalyst or catalyst system to a monolith can be to coat the monolith with a mixture of a catalyst (optionally in oxide form) and an optional metal oxide support layer. For example, a powder of a catalyst oxide and / or a metal oxide support layer can be used to form a coating, which is then applied to the monolith (or other structure). In some aspects, this can result in a catalyst system in which the catalyst is mixed / distributed throughout the metal oxide support layer within the metal oxide support layer, rather than the catalyst being deposited on the metal oxide support layer. In these aspects, at least a portion of the catalyst system can correspond to a mixture of a catalyst and a support layer. In other aspects, any convenient method can be used to deposit or otherwise coat the catalyst and / or catalyst system on the monolith or other structure. The weight of the catalyst and / or catalyst system on the monolith (or other structure) can correspond to 0.1wt% to 10wt%, or 0.5wt% to 10wt%, or 2.0wt% to 10wt%, or 0.1wt% to 6.0wt%, or 0.5wt% to 6.0wt%, or 2.0wt% to 6.0wt% of the total weight of the catalyst system plus the monolith.

[0063] The catalyst and / or catalyst system can be applied to a monolith or other structure, for example, by applying the catalyst system as a coating suspension. In order to form a coating suspension, the catalyst and / or catalyst system can be added to water to form an aqueous suspension with 10wt% to 50wt% solids. For example, the aqueous suspension can include 10wt% to 50wt% solids, or 15wt% to 40wt%, or 10wt% to 30wt%. Alternatively, an acid or base can be added to the aqueous suspension to reduce or increase the pH value, respectively, thereby changing the particle size distribution of the alumina catalyst and / or binder particles. For example, acetic acid or another organic acid can be added to bring the pH value to 3 to 4. The suspension can then be ball-milled (or treated in another way) to obtain the desired particle size of the catalyst particles, such as a particle size of 0.5μm to 5μm. After grinding, the suspension can be stirred until the time of use so that the particles are substantially uniformly distributed in the solution.

[0064] The coating suspension can then be applied to the monolith structure to achieve a desired amount of catalyst (e.g., nickel or rhodium) on the monolith surface. For example, in one aspect, a coating thickness of 10 microns is achieved by forming a coating corresponding to 10 wt % of the monolith structure. Any convenient type of monolith structure can be used to provide a large surface area for supporting catalyst particles. The coating can be applied to the monolith to form a unit having an inner surface coated with the catalyst. One option for applying the coating can be to immerse or otherwise submerge the monolith in the coating suspension.

[0065] After cleaning the excess coating in the unit channels, the catalyst system coated on the monolith can be optionally dried. Drying can correspond to heating at 100° C. to 200° C. for 0.5 to 24 hours. After any optional drying, calcination can be performed. In some aspects, calcination can correspond to heating at 200° C. to 800° C. for 0.5 to 24 hours.

[0066] In other aspects, a high temperature calcination step can be used such that the catalyst system coated on the monolith is calcined at a temperature substantially similar to or greater than the peak temperature to which the monolith will be exposed during the cyclic high temperature reforming reaction. For a monolith in a high temperature zone, this can correspond to calcining the catalyst system coated on the monolith at a temperature of 800° C. or higher, or 1000° C. or higher, or 1200° C. or higher, or 1300° C. or higher (e.g., up to 1600° C. or possibly higher). Notably, if multiple catalyst zones are present, the calcination of the monolith in different catalyst zones can be different.

[0067] Surprisingly found that calcining at a temperature similar to or greater than the peak temperature in the cyclic high temperature reforming process can unexpectedly allow the activity of the catalyst system and / or the adhesion of the catalyst system to the lower monolith to be improved. Not bound by any particular theory, it is believed that exposing the monolith and the deposited catalyst system to high temperature before the catalyst is exposed to the cyclic reaction environment can promote the formation of a stable interface between the catalyst system and the monolith. Then, this stable interface can have the resistance to the enhancement of high temperature oxidation and / or reduction environment in the reforming process, thereby obtaining the stability for the enhancement of the catalyst system being maintained on the monolith surface.

[0068] One of the differences between using a catalyst system that includes a thermally stable metal oxide and a catalyst system that does not use a thermally stable oxide is that the catalyst system that includes a thermally stable metal oxide may have improved adhesion to the underlying support structure after exposure to a cyclic high temperature reforming environment.

[0069] In various aspects, suitable catalytic metals may include, but are not limited to, Ni, Co, Fe, Pd, Rh, Ru, Pt, Ir, Cu, Ag, Au, Zr, Cr, Ti, V, Mo, Nb, and combinations thereof. Catalytic metals may be selected according to the desired catalytic activity type. Such catalytic metals may be used in catalysts in the form of metal oxides. In some aspects, in order to reform hydrocarbons to produce hydrogen in the presence of H2O and / or CO2, Ni, Rh, Ru, Pd, Pt, Ir, Cu, Co, or combinations thereof may be suitable catalytic metals. Relative to the gross weight of the catalyst system, the weight of the catalytic metal oxide in the catalyst system may be in the range of 0.1wt% to 70wt%, or 1.0wt% to 60wt%, or 2.0wt% to 50wt%. In some aspects, when the catalytic metal corresponds to a precious metal or a noble metal, the weight of the catalytic metal oxide in the catalyst system can be in a range of 0.1 wt % to 10 wt %, or 0.2 wt % to 7.0 wt %, or 0.5 wt % to 4 wt %.

[0070] The catalytic metal can be selected to provide long-term stable performance in a specific temperature region of the catalyst bed. This can achieve stable methane conversion, phase stability with the metal oxide carrier, and reduce or minimize the sintering of the catalytic metal. As an example involving three catalyst regions, the catalyst system in the highest temperature catalytic region (e.g., 800-1250°C) exposed to the highest temperature and some of the most violent temperature fluctuations can be composed of Ni as a catalytic metal (NiO as a catalytic metal oxide) and Al2O3 as a metal oxide carrier. For example, the catalyst system can be formed by using a mixture of NiO and Al2O3 as a coating on an α-Al2O3 monolith. In such an example, the catalyst system in the medium temperature catalytic region (e.g., 600-1150°C) can be composed of Ni and Rh as catalytic metals (NiO and Rh2O3 as catalytic metal oxides) and Al2O3 as a metal oxide carrier. To form the catalyst system, a mixture of NiO and Rh2O3 can be used as a catalytic material and Al2O3 (optionally but preferably α-Al2O3) can be used as a metal oxide carrier material, coated on a monolith consisting of 95wt% α-Al2O3, 4wt% SiO2, and 1wt% TiO2. In such an example, the catalyst system in the low-temperature catalytic region (e.g., 400-1050°C) can be composed of Rh as a catalytic metal (Rh2O3 as a catalytic metal oxide) and α-Al2O3 as a metal oxide carrier. To form the catalyst system, a mixture of Rh2O3 and α-Al2O3 can be used as a catalytic material and coated on a monolith consisting of 93wt% α-Al2O3, 5wt% SiO2, and 2wt% MgO.

[0071] In various aspects, suitable metals for the metal oxide support layer in the catalyst system may include, but are not limited to, Al, Si, Mg, Ca, Sr, Ba, K, Na, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Ni, Co, Y, La, Ce, and combinations thereof. The metal (or metals) of the metal oxide support may be selected so that the metal oxide support is substantially not converted to a metallic form under the reducing conditions in a cyclic reaction environment. For example, when the catalytic metal oxide is NiO, one option for the metal oxide support is Al2O3, preferably α-Al2O3. Another example of a suitable metal oxide support is a mixture of Al2O3 with SiO2, MgO and / or TiO2, optionally combined with NiO as a catalytic metal oxide. In such an example, SiO2 may be combined with Al2O3 to form a mullite phase, which may increase resistance to thermal shock and / or mechanical failure. Additionally or alternatively, in such an example, MgO and / or TiO2 may be added. The weight of the metal oxide support in the catalyst bed may range from 1.0 wt% to 40 wt%, or from 2.0 wt% to 30 wt%, or from 3.0 wt% to 20 wt%, relative to the total weight of the monolith in the catalyst bed.

[0072] In various aspects, the metal oxide support layer (e.g., a thermally stable metal oxide support layer) may correspond to at least one oxide selected from the group consisting of corundum, stabilized zirconia, perovskite, pyrochlore, spinel, hibonite, zeolite, and mixtures thereof. The weight of the metal oxide support may be in the range of 1.0 wt% to 40 wt%, or 2.0 wt% to 30 wt%, or 3.0 wt% to 20 wt%, relative to the total weight of the monolith plus catalyst system.

[0073] One type of metal oxide support layer may correspond to conventional refractory oxides commonly used to form supported catalysts. For example, the metal oxide support may correspond to α-Al2O3, LaAlO3, LaAl 11 O 18 , MgO, CaO, ZrO2, TiO2, CeO2, Y2O3, La2O3, SiO2, Na2O, K2O and mixtures thereof. This group is defined herein as the "corundum" oxide group, although many oxides in this group do not have a corundum lattice structure. For example, both CeO2 and MgO can have a rock salt crystal structure. α-Al2O3 consists essentially of a dense arrangement of oxygen ions, with the oxygen ions being hexagonally closest packed and Al 3+ The ions occupy two-thirds of the available octahedral sites. LaAlO3, often abbreviated as LAO, is an optically transparent ceramic oxide with a distorted perovskite structure. 11 O18 It can be formed by the solid-state reaction of LaAlO3 and α-Al2O3. 11 O 18 The plate-like crystals are particularly suitable for use as metal oxide supports because the catalytic metals can be trapped between the plate-like crystal structures. It inhibits the sintering of minute catalytic metals in the active material coated on the monolithic piece of the catalyst bed. Other examples of oxides from the corundum group may include, but are not limited to: i) 95wt% α-Al2O3 and 5wt% SiO2; ii) 93wt% α-Al2O3, 5wt% SiO2 and 2wt% MgO; iii) 94wt% α-Al2O3, 4wt% SiO2, 2wt% MgO and 1wt% Na2O; iv) 95wt% α-Al2O3, 4wt% SiO2 and 1wt% TiO2; v) 7wt% CeO2 and 93wt% MgO; vi) 5wt% CaO and 95wt% α-Al2O3; vii) 5wt% MgO, 5wt% CeO2 and 90wt% α-Al2O3; viii) 20wt% ZrO2 and 80wt% CeO2, ix) 5wt% CeO2, 20wt% ZrO2 and 75wt% α-Al2O3, and x) 6wt% La2O3 and 94wt% α-Al2O3, based on the weight of the metal oxide support.

[0074] Process Example - Reforming and Heating

[0075] In various aspects, the reforming of hydrocarbons can be carried out under steam reforming conditions in the presence of H2O, under dry reforming conditions in the presence of CO2, or under conditions in which H2O and CO2 are simultaneously present in the reaction environment. As a general overview of the reforming operation in a countercurrent reactor, heat for the reforming reaction is provided by heating in a heating flow tube or a heating flow volume. For example, heat is provided by combustion at a combustion location having a heating flow tube or a heating flow volume. The heat generated by the combustion is then transmitted downstream in the heating flow tube or the heating flow volume by the gas flow of the combustion products and / or any carrier gas (e.g., N2) present in the combustion input flow. Reforming can then be carried out in the reforming flow tube, and the reforming reaction consumes the heat provided by the heating flow tube and / or the heating volume.

[0076] During operation of a countercurrent reforming reactor, fuel and oxidant are introduced into the reactor from the heating end of the reactor. The heat exchanger portion of the reactor may absorb heat, but typically does not include a catalyst for reforming. As the fuel and oxidant pass through the heat exchange portion, heat is transferred from the heat exchange portion to at least one of the fuel and oxidant. Combustion does not occur immediately, but the location of the combustion is controlled to occur in the middle portion of the reactor. The flow of the reactants continues after combustion, resulting in additional transfer of the heat generated by the combustion to the reforming end of the reactor.

[0077] Reactants for reforming can be introduced into the reforming end of the reactor, and thus effectively flow in the opposite direction relative to the heating flow. The bed and / or the monolith in the reactor reforming part may include a catalyst for reforming. In various aspects, at least a portion of the catalyst may correspond to a catalyst formed by a ceramic composition as described herein. When reforming occurs, the heat introduced into the reforming flow channel by heat transfer from the heating flow channel can be consumed by the endothermic reforming reaction. After leaving the reforming zone, the reforming product (and unreacted reactants) are optional but preferably no longer exposed to the reforming catalyst. When the reforming product passes through the heat exchange zone, heat can be transferred from the product to the heating flow channel in the heat exchange zone.

[0078] The reforming reactions carried out within the reactor may correspond to reforming methane and / or other hydrocarbons using steam reforming in the presence of H2O, using dry reforming in the presence of CO2, or using "double" reforming in the presence of H2O and CO2. Examples of stoichiometries for steam, dry, and "double" reforming of methane are shown in Equations (1)-(3).

[0079] (1) Dry reforming: CH4+CO2=2CO+2H2

[0080] (2) Steam reforming: CH4+H2O=CO+3H2

[0081] (3) Double preparation: 3CH4+2H2O+CO2=4CO+8H2.

[0082] As shown in equations (1)-(3), dry reforming can produce a lower H2 to CO ratio than steam reforming. Reforming reactions performed with steam alone can typically produce a H2 to CO ratio of about 3, such as 2.5 to 3.5. In contrast, reforming reactions performed in the presence of CO2 can produce much lower ratios, potentially approaching a H2 to CO ratio of about 1.0 or even lower. By using a combination of CO2 and H2O in the reforming process, the reforming reaction can potentially be controlled to produce a wide variety of H2 to CO ratios in the resulting syngas.

[0083] It is worth noting that the ratio of H2 to CO in the syngas may also depend on the water-gas shift equilibrium. Although the above stoichiometry shows a ratio of about 1 or about 3 for dry reforming and steam reforming, respectively, the balance of H2 and CO in the syngas may be different from the reaction stoichiometry. The balance can be determined based on the water-gas shift equilibrium, which relates the concentrations of H2, CO, CO2, and H2O based on the following reaction,

[0084] (4) H2O + CO <=> H2 + CO2

[0085] Most reforming catalysts, such as rhodium and / or nickel, can also be used as water-gas shift catalysts. Therefore, if the reaction environment producing H2 and CO also includes H2O and / or CO2, the initial stoichiometry of the reforming reaction may change according to the water-gas shift equilibrium. This balance also depends on temperature, and higher temperatures are conducive to the generation of CO and H2O. It is worth noting that higher temperatures can also increase the rate of reaching equilibrium. Therefore, the ability to carry out reforming reactions at high temperatures may bring a variety of benefits. For example, CO2 can be added to the reaction environment instead of steam reforming in an environment containing excess H2O. This can allow both the ratio of H2 to CO produced based on dry reforming stoichiometry to be reduced, and the ratio of H2 to CO produced based on water-gas shift equilibrium to be reduced. Alternatively, if a higher ratio of H2 to CO is required, CO2 can be removed from the environment, and the ratio of H2O to CH4 (or other hydrocarbons) can be controlled to produce the desired type of synthesis gas. By selecting the appropriate amount of feed composition, this can potentially allow the production of a syngas having a ratio of H2 to CO of 0.1 to 15, or 0.1 to 3.0, or 0.5 to 5.0, or 1.0 to 10.

[0086] A common source of methane is natural gas. In some applications, natural gas (including associated hydrocarbons and impurity gases) can be used as a feed for the reforming reaction. The supplied natural gas can also be desulfurized and / or dehydrated natural gas. Natural gas generally includes associated gases of various concentrations, such as ethane and other alkanes, preferably at a concentration lower than that of methane. The supplied natural gas may include impurities, such as H2S and nitrogen. More generally, the hydrocarbon feed for reforming can include any convenient combination of methane and / or other hydrocarbons. Optionally, the reforming feed can also include some hydrocarbon compounds, such as alcohols or mercaptans, which are similar to hydrocarbons, but include one or more heteroatoms different from carbon and hydrogen. In some aspects, the additional components present in the feed can correspond to impurities, such as sulfur, that can be adsorbed onto the catalytic monolith during the reduction cycle (e.g., reforming cycle). Such impurities can be oxidized to form sulfur oxides in subsequent cycles, which can then be reduced to release additional sulfur-containing components (or other impurity-containing components) into the reaction environment.

[0087] In some aspects, the reformate feed may include 5 wt% or more C 2+Compounds, such as ethane or propane, or 10wt% or more, or 15wt% or more, or 20wt% or more, such as up to 50wt% or possibly higher. It is worth noting that nitrogen and / or other gases that do not react in the combustion environment, such as H2O and CO2, may also be present in the reforming feed. In terms of the reformer corresponding to an onboard reforming environment, such non-reactive products can be optionally introduced into the feed, such as based on exhaust gas recirculation to the reformer. In addition or alternatively, the reforming feed may include 40wt% or more of methane, or 60wt% or more, or 80wt% or more, or 95wt% or more, such as a feed (98wt% or more) substantially consisting of methane. In terms of reforming corresponding to steam reforming, the molar ratio of steam molecules to carbon atoms in the feed can be 0.3 to 4.0. It is worth noting that methane has 1 carbon atom per molecule, while ethane has 2 carbon atoms per molecule. In aspects where the reforming corresponds to dry reforming, the molar ratio of CO2 molecules to carbon atoms in the feed can be from 0.05 to 3.0.

[0088] In the reforming zone of a countercurrent reactor, due to the nature of the way in which heat is added to the reactor and / or due to the kinetics of the reforming reaction, the temperature can vary throughout the region. The highest temperature portion of the region can generally be located near the middle portion of the reactor, such as at or near the interface between the reforming flow channel and the mixer element. If the monolith with the reforming catalyst extends into the mixing zone, at least a portion of the mixing zone can correspond to a portion of the reforming zone. Therefore, the position at which combustion begins during regeneration can generally be near the end of the reforming zone in the reactor. From the center of the reactor (and / or from the position of the highest temperature) to the end of the reactor, the temperature can be reduced. Therefore, the temperature at the beginning of the reforming zone (at the end of the reactor) can be lower than the temperature at the end of the reforming zone (at the middle portion of the reactor).

[0089] In order to generate heat in the heating flow channel, fuel and oxygen such as methane, natural gas or H2 can be introduced into the reactor and burned. The position allowing fuel and oxidant to mix can be controlled in any convenient way, for example, by introducing fuel and oxidant through different channels. By delaying combustion until reactants arrive at the center of the reactor, the non-reforming end of the reactor can be maintained at a cooler temperature. This may also cause the center of the reactor to reach a temperature peak. Alternatively, the temperature peak can be located in the part of the reactor that also includes a reforming catalyst.

[0090] Since heat is transferred from the heating flow channel (and / or the heating flow volume) to the reforming flow channel, the peak temperature may be different in two different types of flow channels. In the heating flow channel, the peak temperature may be 1100°C or higher, or 1200°C or higher, or 1300°C or higher, or may be a higher temperature, such as up to 1500°C or possibly higher. In the reforming flow channel, the peak temperature may be 750°C to 1200°C, or 750°C to 1100°C, or 750°C to 1000°C, or 850°C to 1200°C, or 850°C to 1100°C, or 950°C to 1200°C. It is worth noting that at temperatures below about 500°C, reforming is reduced or minimized. In some aspects, the peak temperature in the reforming channel may be high enough so that the temperature at the end of the reforming channel remains above 500°C.

[0091] In various aspects, the reaction conditions for reforming hydrocarbons may include one or more of the following: an average reforming zone temperature range of 400°C to 1000°C, or 400°C to 800°C, or 500°C to 1000°C, or 500°C to 800°C, or 600°C to 1000°C; a peak temperature in the reforming zone / in the reforming flow channel of 750°C to 1200°C, or 750°C to 1100°C, or 750°C to 1000°C, or 850°C to 1200°C, or 850°C to 1100°C, or 950°C to 1200°C; and a difference between the temperature in the reforming flow channel at the end of the heat exchange zone and the peak temperature in the reforming flow channel of 100°C to 800°C, or 100°C to 600°C, or 100°C to 400°C, or 200°C to 800°C, or 200°C to 600°C. Alternatively, the difference between the peak temperature in the reforming flow channel and the temperature in the reforming flow channel at the end of the reforming zone (where the reforming input flow enters the reactor) may be 50°C to 500°C, or 100°C to 500°C, or 50°C to 300°C, or 100°C to 300°C.

[0092] Additionally or alternatively, the reaction conditions for reforming hydrocarbons may include a pressure of 0 psig to 1500 psig (10.3 MPa), or a pressure of 0 psig to 1000 psig (6.9 MPa), or a pressure of 0 psig to 550 psig (3.8 MPa); a gas hourly space velocity of 1000 hr. -1 Up to 50,000hr -1 The space velocity corresponds to the volume of reactants per unit time relative to the monolith volume. The monolith volume is defined as the volume of the monolith as if it were a solid cylinder.

[0093] In some aspects, the advantage of operating the reforming reaction at high temperature can be that substantially all of the methane and / or other hydrocarbons in the reforming feed can be converted. For example, for a reforming process (i.e., steam reforming or double reforming) in which water is present in the reforming reaction environment, the reaction conditions may be suitable for converting 10wt% to 100wt% of the methane in the reforming feed, or 20wt% to 80wt%, or 50wt% to 100wt%, or 80wt% to 100wt%, or 10wt% to 98wt%, or 50wt% to 98wt%. Additionally or alternatively, the reaction conditions may be suitable for converting 10wt% to 100wt% of the hydrocarbons in the reforming feed, or 20wt% to 80wt%, or 50wt% to 100wt%, or 80wt% to 100wt%, or 10wt% to 98wt%, or 50wt% to 98wt%.

[0094] In other aspects, for reforming processes in which carbon dioxide is present in the reforming reaction environment (i.e., dry reforming or dual reforming), the reaction conditions may be suitable for converting 10 wt% to 100 wt% of the methane in the reforming feed, or 20 wt% to 80 wt%, or 50 wt% to 100 wt%, or 80 wt% to 100 wt%, or 10 wt% to 98 wt%, or 50 wt% to 98 wt% of the methane in the reforming feed. Additionally or alternatively, the reaction conditions may be suitable for converting 10 wt% to 100 wt% of the hydrocarbons in the reforming feed, or 20 wt% to 80 wt%, or 50 wt% to 100 wt%, or 80 wt% to 100 wt%, or 10 wt% to 98 wt%, or 50 wt% to 98 wt% of the hydrocarbons in the reforming feed.

[0095] In some alternative aspects, the reforming reaction can be carried out under dry reforming conditions, wherein the reforming is carried out with CO2 as a reagent, but the amount of H2O in the reaction environment is reduced or minimized. In such alternative aspects, the goal of the reforming reaction can be to produce a synthesis gas having a ratio of H2 to CO of 1.0 or less. In some aspects, the temperature during reforming can correspond to the temperature range described in steam reforming. Alternatively, in some aspects, the dry reforming reaction can be carried out at a lower temperature between 500°C and 700°C or 500°C and 600°C. In these aspects, the ratio of H2 to CO can be 0.3 to 1.0, or 0.3 to 0.7, or 0.5 to 1.0. Carrying out a dry reforming reaction under these conditions can also result in a large amount of coke generation, which may need to be removed during the regeneration process to maintain catalytic activity.

[0096] Example of an alternative process - partial oxidation for heating

[0097] In certain alternative aspects, reforming can be performed in the reforming flow channel and the heating flow channel. This can be achieved by operating the heating flow channel under partial oxidation conditions.

[0098] In the partial oxidation process, hydrocarbons are exposed to combustion conditions, but the amount of oxygen provided to the reaction environment is less than the stoichiometric amount. Therefore, the substoichiometric amount of O2 present under the partial oxidation conditions does not form primarily CO2 and H2O, but rather forms a mixture of CO2, CO, H2, and H2O. Partial oxidation-based hydrocarbon reforming generally produces a relatively low molar ratio of H2 to CO, such as a molar ratio of about 1.4 to 1.7. Optionally, the partial oxidation product can be exposed to water gas shift reaction conditions to form additional H2 from a portion of the CO and H2O present in the partial oxidation product.

[0099] It is noteworthy that partial oxidation generally results in less heat generation per mole of hydrocarbons in the input stream because much less exothermic product (CO) is formed from at least a portion of the fuel. Thus, operation under partial oxidation conditions may involve increasing the relative flow rate of the heating stream input in order to generate sufficient heat under partial oxidation conditions to maintain a target amount of reforming in the reforming stream channel.

[0100] In some alternative aspects, by including a limited amount of reforming catalyst in the heating flow channel, the ratio of H2 to CO in the partial oxidation product can be further increased. It is worth noting that the amount of reforming catalyst in the heating flow channel is limited by the fact that the heating flow channel also needs to provide heat for the reforming reaction in the reforming flow channel. Generally, this means that the amount of reforming catalyst in the heating flow channel will be smaller relative to the amount of catalyst in the reforming flow channel. The relative amount of reforming catalyst in the heating flow channel and the reforming flow channel can be determined by, for example, comparing the total weight of the catalyst in the heating flow channel with the total weight of the reforming catalyst in the reforming flow channel. For example, this can be calculated by multiplying the average catalyst density in one type of flow channel by the surface area covered by the average catalyst density. In some aspects, the total weight of the reforming catalyst in the heating flow channel can be 25% or less of the total weight of the reforming catalyst in the reforming flow channel, or 15% or less, or 10% or less, or 5.0% or less, or 3.0% or less, such as as low as 0.1% of the total weight or possibly lower. In the aspect that the reforming catalyst is provided in the form of a catalyst system, the comparison is based on the weight of the catalyst system in the heating flow channel and the reforming flow channel. It should be noted that the catalyst in the heating flow channel may be different from the catalyst in the reforming flow channel. Even if the reforming catalyst / catalyst system between the heating flow channel and the reforming flow channel is different, the total weight comparison can still be performed.

[0101] By incorporating a limited amount of reforming catalyst in the heating stream tubes, the molar ratio of H2 to CO in the heating stream output can be increased from about 1.4 to 1.7 for typical PO x The values ​​increase to higher values ​​of 1.8 to 2.1.

[0102] In certain aspects, one strategy for incorporating a reforming catalyst may be to incorporate a limited amount of reforming catalyst at a location downstream of where the partial oxidation reaction begins. Figure 1 In addition to the mixing and heat exchanger parts, a series of 5 monoliths are shown as part of the internal structure of the reactor. In this embodiment, the reforming catalyst can be contained only in the heating flow channel of the second monolith from the left. This will allow the reforming catalyst in the heating flow channel to deviate from the mixer / monolith interface, and partial oxidation will start from this interface (due to the mixing delay of fuel and oxidant to approximately this position). Therefore, the reforming catalyst will not be in the highest temperature area. This position of the reforming catalyst means that the reforming catalyst in the heating flow channel is still relatively far away from the end of the reactor, so the reforming catalyst is not present in the colder part of the reactor. This avoids the situation where the reforming catalyst reduces the ratio of H2 to CO based on the water-gas shift activity under lower temperature conditions.

[0103] In some aspects, to help make hydrocarbons available for reforming by the reforming catalyst, additional fuel can be introduced into the reactor at a downstream location in the heated flow channel or near the location of the reforming catalyst. Partial oxidation conditions will produce H2O and CO2, so by adding additional fuel at or near the location of the reforming catalyst in the heated flow channel, PO can be increased. x The amount of hydrocarbons available downstream of the reaction initiation.

[0104] In other aspects, the reforming catalyst can be located closer to the mixer / monolith interface so that the reforming catalyst in the heated flow channels is present at or near the location in the reactor where the partial oxidation reaction begins. In this aspect, the reforming reaction directly competes and / or supplements the partial oxidation reaction occurring at or near the mixer interface.

[0105] Example - Temperature profile during countercurrent reforming

[0106] Figure 3 An example of a temperature profile within the reforming flow channel / tube during counter-flow reforming is shown. The temperature profile may also represent the temperature within the heating flow channel tube. Figure 3 Temperature values ​​are not provided on the vertical axis in the . This is because the temperature values ​​will vary depending on the peak temperature selected, the flow rate in the individual flow channels / tubes, and based on other factors.

[0107] Figure 3The temperature curve in corresponds to the curve for a pilot scale reactor with a size of 12 inches. The interface between the mixer element and the monolith / reforming flow tube is 4 inches. This corresponds to the position where the fuel and oxidant are allowed to mix during operation, and therefore this is where the peak temperature occurs. The temperature towards the heat exchanger end of the reactor drops sharply from the peak temperature. This is because the only heat that is transferred to the heat exchanger end of the reactor is the heat carried by the reforming flow products. In contrast, the heat from the combustion reaction is transferred to the reforming end by the larger volume of the combustion flow, resulting in higher temperatures in most of the reforming zone.

[0108] In some aspects, the peak temperature of the heating flow channel / tube can be 1100°C or higher, or 1200°C or higher, such as up to 1500°C or possibly higher. In some aspects, the peak temperature of the reforming flow channel can be 750°C to 1200°C, or 750°C to 1100°C, or 750°C to 1000°C, or 850°C to 1200°C, or 850°C to 1100°C, or 950°C to 1200°C. In some aspects, the difference between the peak temperature in the reforming flow channel and the temperature in the reforming flow channel at the heat exchange end can be 100°C to 800°C, or 100°C to 600°C, or 100°C to 400°C, or 200°C to 800°C, or 200°C to 600°C. In some aspects, the difference between the peak temperature in the reforming flow channel and the temperature in the reforming flow channel at the end of the reforming zone (i.e., where the reforming input flow enters the reactor) can be 50°C to 500°C, or 100°C to 500°C, or 50°C to 300°C, or 100°C to 300°C.

[0109] Additional Implementations

[0110] Embodiment 1. A method for performing countercurrent reforming, comprising: delivering a fuel to a fuel flow path in a heat exchange zone of a reactor volume and delivering an oxygen-containing gas to an oxidant flow path in the heat exchange zone of the reactor volume; delivering a reforming input flow comprising at least one hydrocarbon to a plurality of reforming flow channels in the reforming zone of the reactor volume, wherein the flow direction of the reforming input flow is substantially countercurrent to the flow direction of at least one of the fuel and the oxygen-containing gas, and the reforming channels include a reforming catalyst located in the reforming zone; mixing in one or more heating flow channels in a mixing zone of the reactor volume The fuel and the oxygen-containing gas are mixed to form a fuel mixture, the mixing zone is adjacent to the heat exchange zone, and the opposite side of the mixing zone is adjacent to the reforming zone; the mixture is reacted in one or more heating flow channels within at least one of the mixing zone and the reforming zone to produce heat and an oxidation product flow, and the one or more heating flow channels are arranged around a plurality of reforming flow channels; under reforming conditions, at least a portion of the at least one hydrocarbon in the reforming channel is reformed to form a reformed product flow; the reformed product flow is discharged from the heat exchange zone; and the oxidation product flow is discharged from the reforming zone.

[0111] Embodiment 2. The method of embodiment 1, wherein the peak temperature in the reformate flow channel is 200° C. or more higher than the temperature in the reformate flow channel at the end of the heat exchanger zone.

[0112] Embodiment 3. The method of embodiment 1 or 2, wherein the peak temperature in the reforming flow channel is 50° C. or more higher than the temperature in the reforming flow channel at the end of the reforming zone.

[0113] Embodiment 4. The method of any of the above embodiments, wherein the plurality of reformate flow channels comprises a plurality of channels in one or more monolithic pieces.

[0114] Embodiment 5. The method of embodiment 4, wherein the one or more heating flow channels include multiple channels in one or more integral parts; or wherein the reforming zone includes multiple first integral parts and multiple second integral parts, the multiple first integral parts include multiple reforming flow channels, and the multiple second integral parts include multiple heating flow channels; or a combination thereof.

[0115] Embodiment 6. The method of any of the above embodiments, wherein the fuel flow path and the oxidant flow path comprise channels in one or more heat exchanger monoliths.

[0116] Embodiment 7. The method of any of Embodiments 1-3, wherein the plurality of reformate flow channels comprises a plurality of tubes, the reactor volume comprises a reactor shell, the plurality of tubes optionally comprising a plurality of monoliths contained within the plurality of tubes.

[0117] Embodiment 8. The method of embodiment 7, wherein the reactor includes a shell, the fuel flow path includes a portion of the reactor volume within the shell, and the oxidant flow path includes one or more conduits that provide fluid communication between the end of the heat exchange zone and the mixing zone.

[0118] Embodiment 9. A method according to any of the above embodiments, a) wherein the reforming flow channel is not substantially fluidically connected to the heating flow channel; b) wherein reforming at least a portion of the at least one hydrocarbon comprises reforming without exposing a portion of the fuel, a portion of the oxidant flow, or a portion of the oxidation product flow to reforming conditions; c) wherein the reforming input flow and the reforming product flow are not mixed with the fuel, oxygen-containing gas, and oxidation product flow in the reforming flow channel; or d) a combination of two or more of a), b) and c) above.

[0119] Embodiment 10. The method of any of the above embodiments, wherein the reaction comprises partial oxidation of the fuel, and the oxidation products comprise CO, CO2, and H2O.

[0120] Embodiment 11. The method of embodiment 10 further includes reforming at least a portion of the fuel by exposing at least a portion of the fuel in the heating flow channel to a second reforming catalyst in the heating flow channel, wherein optionally, the total weight of the second reforming catalyst in the heating flow channel is 25% or less of the total weight of the reforming catalyst in the reforming flow channel.

[0121] Embodiment 12. A countercurrent reforming reactor, comprising: a reactor volume, wherein the reactor volume includes a heat exchange zone, one or more mixing elements in a mixing zone, a reforming zone, a plurality of first flow channels and one or more second flow channels, at least a portion of the plurality of first flow channels are located in the reforming zone, at least a portion of the plurality of first flow channels include a reforming catalyst located on one or more surfaces of the plurality of first flow channels in the reforming zone, the mixing zone is adjacent to the heat exchange zone, the opposite side of the mixing zone is adjacent to the reforming zone, the one or more second flow channels are arranged around the plurality of first flow channels, wherein the heat exchange zone includes at least an oxidant flow path and a fuel flow path, at least one of the fuel flow path and the oxidant flow path provides fluid connection between an end of the heat exchange zone and the mixing zone, but does not provide fluid connection between the oxidant flow path and the fuel flow path in the heat exchange zone.

[0122] Embodiment 13. The reactor of Embodiment 12, wherein the plurality of first flow channels and the one or more second flow channels comprise channels in one or more monolithic pieces.

[0123] Embodiment 14. The reactor of Embodiment 12, wherein the plurality of first flow channels comprise tubes and the one or more second flow channels comprise a reactor volume in the reforming zone.

[0124] Embodiment 15. The reactor of embodiment 14, wherein the second flow channel further comprises a second reforming catalyst on one or more surfaces of the plurality of second flow channels in the reforming zone, and the total weight of the second reforming catalyst is 25% or less of the total weight of the reforming catalyst.

[0125] Additional Embodiments A. The method of any of the above embodiments, wherein the reaction comprises combustion of a fuel and an oxygen-containing gas.

[0126] Although the present invention has been described and illustrated by specific embodiments, those skilled in the art will appreciate that the invention lends itself to variations not necessarily illustrated herein. Therefore, for this reason, only reference should be made to the appended claims to determine the true scope of the present invention.

Claims

1. A method for countercurrent reforming, comprising: delivering a fuel to a fuel flow path within a heat exchange zone of a reactor volume and delivering an oxygen-containing gas to an oxidant flow path within the heat exchange zone of the reactor volume; delivering a reforming input stream comprising at least one hydrocarbon to a plurality of reforming flow channels in a reforming zone of the reactor volume, the reforming input stream flowing in a direction that is substantially countercurrent to the flow of at least one of the fuel and the oxygen-containing gas, the reforming channels comprising a reforming catalyst located in the reforming zone; mixing the fuel and the oxygen-containing gas to form a fuel mixture in one or more heating flow channels in a mixing zone of the reactor volume, the mixing zone being adjacent to the heat exchange zone and having an opposite side of the mixing zone being adjacent to the reforming zone; reacting the mixture in one or more heating flow channels within at least one of the mixing zone and the reforming zone to produce a hot and oxidized product stream, the one or more heating flow channels being arranged around a plurality of reforming flow channels; reforming at least a portion of the at least one hydrocarbon in the reforming passage under reforming conditions to form a reformate stream; discharging the reformate stream from the heat exchange zone; and discharging the oxidation product stream from the reforming zone. 2 . The method according to claim 1 , wherein a peak temperature in the reformed flow channel is 200° C. or more higher than a temperature in the reformed flow channel at an end of the heat exchanger zone. 3 . The method according to claim 1 , wherein a peak temperature in the reforming flow channel is 50° C. or more higher than a temperature in the reforming flow channel at an end of the reforming zone.

4. The method of any one of the preceding claims, wherein the plurality of reformate flow channels comprises a plurality of channels in one or more monolithic pieces.

5. The method according to claim 4, wherein the one or more heating flow channels include multiple channels in one or more integral parts; or wherein the reforming zone includes multiple first integral parts and multiple second integral parts, the multiple first integral parts include multiple reforming flow channels, and the multiple second integral parts include multiple heating flow channels; or a combination thereof.

6. A method according to any one of the preceding claims, wherein the fuel flow path and the oxidant flow path comprise channels in one or more heat exchanger monoliths.

7. The method of any one of claims 1-3, wherein the plurality of reformate flow channels comprises a plurality of tubes, the reactor volume comprises a reactor shell, the plurality of tubes optionally comprising a plurality of monoliths contained within the plurality of tubes.

8. A method according to claim 7, wherein the reactor includes a shell, the fuel flow path includes a portion of the reactor volume within the shell, and the oxidant flow path includes one or more conduits that provide fluid communication between the end of the heat exchange zone and the mixing zone.

9. A method according to any one of the above claims, a) wherein the reforming flow channel is not substantially fluidly connected to the heating flow channel; b) wherein reforming at least a portion of the at least one hydrocarbon comprises reforming without exposing a portion of the fuel, a portion of the oxidant flow, or a portion of the oxidation product flow to reforming conditions; c) wherein the reforming input flow and the reforming product flow are not mixed with the fuel, oxygen-containing gas, and oxidation product flow in the reforming flow channel; or d) a combination of two or more of a), b) and c) above.

10. A method according to any one of the preceding claims, wherein the reaction comprises partial oxidation of the fuel, the oxidation products comprising CO, CO2 and H2O.

11. The method according to claim 10 further includes reforming at least a portion of the fuel by exposing at least a portion of the fuel in the heating flow channel to a second reforming catalyst within the heating flow channel, wherein optionally, the total weight of the second reforming catalyst in the heating flow channel is 25% or less of the total weight of the reforming catalyst in the reforming flow channel.

12. A countercurrent reforming reactor comprising: A reactor volume, the reactor volume comprising a heat exchange zone, one or more mixing elements in a mixing zone, a reforming zone, a plurality of first flow channels and one or more second flow channels, at least a portion of the plurality of first flow channels being located in the reforming zone, at least a portion of the plurality of first flow channels comprising a reforming catalyst located on one or more surfaces of the plurality of first flow channels in the reforming zone, the mixing zone being adjacent to the heat exchange zone, an opposite side of the mixing zone being adjacent to the reforming zone, the one or more second flow channels being arranged around the plurality of first flow channels, wherein the heat exchange zone comprises at least an oxidant flow path and a fuel flow path, at least one of the fuel flow path and the oxidant flow path providing fluid communication between an end of the heat exchange zone and the mixing zone, but not providing fluid communication between the oxidant flow path and the fuel flow path in the heat exchange zone.

13. The reactor of claim 12, wherein the plurality of first flow channels and the one or more second flow channels comprise channels in one or more integral pieces.

14. The reactor of claim 12, wherein a plurality of first flow channels comprise tubes and one or more second flow channels comprise a reactor volume in the reforming zone.

15. The reactor according to claim 14, wherein the second flow channel further comprises a second reforming catalyst on one or more surfaces of the plurality of second flow channels in the reforming zone, and the total weight of the second reforming catalyst is 25% or less of the total weight of the reforming catalyst.

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