Improved pressure swing adsorption recovery using hydrogen membranes

Abstract

Systems and methods are provided for increasing total hydrogen (H2) recovery at high purity when using pressure swing adsorption to recover hydrogen from a stream containing one or more contaminants. The total hydrogen recovery is increased by performing a membrane separation on the hydrogen-containing feed stream prior to introducing the hydrogen-containing feed stream into the pressure swing adsorption apparatus. This separation is performed using a membrane that is selective for allowing hydrogen to pass through into the permeate. The resulting permeate contains less than 5.0 mol% of the hydrogen from the hydrogen-containing feed stream, which means that the remaining 95+ mol% of the hydrogen in the hydrogen-containing feed stream continues on for purification via pressure swing adsorption. The resulting permeate is at a substantially lower pressure than the hydrogen-containing feed stream, and has a purity of 85 vol% or higher of hydrogen.

Description

IMPROVED PRESSURE SWING ADSORPTION RECOVERY USING HYDROGEN MEMBRANESFIELD OF THE INVENTION

[0001] Systems and methods are provided for improving hydrogen recovery by integration of a membrane hydrogen recovery process with a pressure swing adsorption process.BACKGROUND OF THE INVENTION

[0002] A variety of methods are now available for using hydrocarbons as a feed source for generation of synthesis gas, or syngas. Synthesis gas is a mixture of hydrogen, carbon oxides, and water. While some processes can use synthesis gas as an input stream, for many applications it is desirable to separate the synthesis gas to recover a high purity hydrogen stream. When forming such a high purity hydrogen stream, it is also desirable to recover as much of the hydrogen as possible from the synthesis gas stream.

[0003] Pressure swing adsorption (PSA) is a commonly used method for forming a high purity hydrogen-containing product from a feed that contains both hydrogen and carbon oxides. As implied by the name of the process, PSA operates in part based on a pressure differential between the adsorption step and the desorption step. When using PSA for separation of hydrogen from a feed, the adsorption step is used to selectively adsorb components other than hydrogen. In the case of synthesis gas, this corresponds to selective adsorption of carbon oxides. After the adsorption step, the adsorbent bed is regenerated in part by reducing the pressure of the adsorbent bed environment.

[0004] One of the advantages of PSA processes is that a high purity hydrogen product can be generated at an elevated pressure. This is in contrast to membrane separations of hydrogen, where the high purity hydrogen stream is typically a lower pressure permeate stream.

[0005] Similar to most types of separation processes, PSA processes have a tradeoff between the amount of hydrogen recovered from a feed and the purity of hydrogen in the resulting product. For many of the applications where a high purity hydrogen-containing stream is useful, the target purity is a hydrogen content of 99.0 vol% or more. PSA processes can readily achieve such a hydrogen content for hydrogen-containing product. However, achieving this level of purity typically results in recovery of only 90 mol% to 95 mol% of the hydrogenin the initial feed that contains the hydrogen and carbon oxides. The remaining hydrogen in the feed is lost during depressurization of the adsorbent bed and / or during purging of the adsorbent bed as part of desorbing the carbon oxides to regenerate the adsorbent bed.

[0006] A variety of complex schemes have been proposed to mitigate this loss of hydrogen. Some of these schemes including performing membrane separations on the depressurization output and / or the purge output to separate out hydrogen from these streams. This hydrogen is recycled for inclusion as part of the initial feed to the PSA process. U.S. Patent 5,573,010 describes an example of this type of scheme for increasing hydrogen recovery.

[0007] It would be desirable to have improved systems and methods to allow for increased hydrogen recovery from a synthesis gas stream while still maintaining high purity for the resulting recovered hydrogen.SUMMARY OF THE INVENTION

[0008] In an embodiment, a method for separating hydrogen from an input gas stream containing hydrogen and at least one carbon oxide is provided. The method includes providing an input gas stream containing 70 vol% or more of H2 on a dry basis and at least one of CO and CO2, the input gas stream having a partial pressure of H2 of 1 .4 MPa or higher. The method further includes performing a membrane separation on at least a portion of the input gas stream to form a permeate containing 1.0 vol% to 5.0 vol% of the H2 present in the input gas stream and a retentate. Additionally, the method includes passing a swing adsorption input stream comprising at least a portion of the retentate into a pressure swing adsorption stage to form a hydrogen-containing product and at least one tail gas stream. The hydrogen-containing product can have an H2 content of 95 vol% or more. The swing adsorption input stream can have a total pressure of 1.5 MPa-a or higher. Optionally, the combined H2 content of the permeate and the hydrogen-containing product correspond to a recovery of 90 mol% or more of the H2 in the input gas stream.

[0009] In another embodiment, a method for separating hydrogen from an input gas stream containing hydrogen and at least one carbon oxide is provided. The method includes providing an input gas stream containing H2, CO, CO2, and H2O, the input gas stream having 60 vol% or more of H2 on a dry basis and having a partial pressure of H2 of 1.4 MPa or higher. A molar ratio of water to carbon oxides in the input gas stream can be 1.2 or less. The methodfurther includes performing a membrane separation on at least a portion of the input gas stream to form a permeate containing H2 present in the input gas stream and a retentate. The method further includes passing the retentate into a water gas shift stage to form a shifted retentate. Additionally, the method includes passing a swing adsorption input stream containing at least a portion of the shifted retentate into a pressure swing adsorption stage to form a hydrogencontaining product and at least one tail gas stream, the hydrogen-containing product having an H2 content of 95 vol% or more on a dry basis. The swing adsorption input stream can have a total pressure of 1.5 MPa-a or higher. The at least a portion of the shifted retentate can contain 70 vol% or more of H2 on a dry basis. The combined H2 content of the permeate and the hydrogen-containing product correspond to a recovery of 90 mol% or more of the H2 in the input gas stream.BRIEF DESCRIPTION OF THE DRAWING

[0010] FIG. 1 shows an example of a configuration for separating hydrogen from a stream containing hydrogen and at least one carbon oxide.

[0011] FIG. 2 shows another example of a configuration for separating hydrogen from a stream containing hydrogen and at least one carbon oxide.DETAILED DESCRIPTION OF THE EMBODIMENTS

[0012] All numerical values within the detailed description and the claims herein are modified by “about” or “approximately” the indicated value, and take into account experimental error and variations that would be expected by a person having ordinary skill in the art.Overview

[0013] In various embodiments, systems and methods are provided for increasing total hydrogen (H2) recovery at high purity when using pressure swing adsorption to recover hydrogen from a stream containing one or more contaminants. The total hydrogen recovery is increased by performing a membrane separation on the hydrogen-containing feed stream prior to introducing the hydrogen-containing feed stream into the pressure swing adsorption apparatus. This separation is performed using a membrane that is selective for allowing hydrogen to pass through into the permeate. The resulting permeate contains less than 5.0 mol% of the hydrogen from the hydrogen-containing feed stream, which means that theremaining 95+ mol% of the hydrogen in the hydrogen-containing feed stream continues on for purification via pressure swing adsorption. The resulting permeate is at a substantially lower pressure than the hydrogen-containing feed stream, and has a purity of 85 vol% or higher of hydrogen (which is higher than the purity of the hydrogen-containing feed stream). Thus, the permeate corresponds to a low pressure hydrogen-containing stream. In aspects where a water gas shift stage is included to increase the hydrogen content in the feed to the PSA process, the membrane separation can be performed prior to or after the water gas shift stage. When the partial pressure of hydrogen in the hydrogen-containing feed stream is greater than 1.4 MPa, or greater than 2.2 MPa, performing an initial membrane separation to form a low pressure, low purity hydrogen permeate allows for an increase in the net recovery of hydrogen from the hydrogen-con taining feed stream, but with a small portion of the hydrogen being in a second stream at a substantially lower pressure.

[0014] Potential contaminants that can be separated during hydrogen recovery using pressure swing adsorption include, but are not limited to, carbon monoxide, carbon dioxide, methane, nitrogen, or a combination thereof. As an example, various types of reforming processes can be used to form synthesis gas, which is a combination of H2, CO, CO2, and H2O. Synthesis gas is an example of an input gas stream that is often used as a source for generating high purity hydrogen streams via separation using pressure swing adsorption. Depending on the nature of the process for making synthesis gas, methane and / or nitrogen can also be present as additional contaminants in a synthesis gas. As another example, methane pyrolysis can generate hydrogen-containing output flows that primarily contain hydrogen, but that also potentially contain methane and nitrogen.

[0015] There are two primary strategies for using pressure swing adsorption for hydrogen recovery from a stream containing carbon oxides, methane, and / or hydrogen. One option is to perform the desorption step at a pressure below roughly 90 kPa-a (below ambient pressure), which can be referred to as performing the desorption step under “vacuum” conditions. This is sometimes referred to as vacuum pressure swing adsorption. While vacuum pressure swing adsorption can be effective, such configurations also require substantial additional equipment and are more costly to operate.

[0016] The other primary strategy is to introduce the hydrogen-containing feed into the PSA apparatus at a sufficiently high pressure that desorption can occur at a pressure of 90 kPa- a or higher. For this type of PSA process, increasing the input pressure for the feed to the PSAapparatus can generally help with increasing the amount of hydrogen recovered at a target hydrogen purity, as well as increasing the amount of gas that can be processed within a given apparatus footprint. However, the benefits of continuing to increase the input pressure drop off at partial pressures of hydrogen of 1.4 MPa or higher, or 2.2 MPa or higher. Beyond a partial pressure of hydrogen of 1.4 MPa, or beyond a partial pressure of hydrogen of 2.2 MPa, additional increases in the partial pressure of hydrogen in the input feed result in only modest gains in hydrogen recovery.

[0017] In various embodiments, a combination of membrane separation and pressure swing adsorption can be used to increase total hydrogen recovery when forming a high purity hydrogen stream from an input stream that has a hydrogen partial pressure of 1.4 MPa or higher, or 2.2 MPa or higher. Generally, increasing the hydrogen partial pressure to values above 1.4 MPa, or above 2.2 MPa, can be beneficial for increasing the throughput for a PSA system. However, the amount of increase in hydrogen recovery with increasing pressure is reduced or minimized for hydrogen partial pressure values above 1.4 MPa, or above 2.2 MPa. As a result, a net increase in hydrogen recovery can be achieved by performing an initial membrane separation prior to passing the hydrogen-containing feed into the PSA system.

[0018] The initial membrane separation is designed to form a permeate that contains a relatively small portion of the hydrogen present in the hydrogen-containing feed. In some aspects, the amount of hydrogen in the permeate from the initial membrane corresponds to 1.0 mol% to 5.0 mol% of the hydrogen in the hydrogen-containing feed. Conventionally, reducing the partial pressure of hydrogen prior to entering the PSA system would be viewed as a disadvantage, as reducing the partial pressure of hydrogen will reduce the hydrogen recovery in the PSA product. However, because the reduction in partial pressure of the hydrogen- containing feed due to forming this permeate is relatively low (due to the permeate only containing 1.0 mol% to 5.0 mol% of the hydrogen from the original input flow), the net recovery of the combined permeate and PSA product is greater than simply recovering the PSA product alone in the absence of forming the permeate.

[0019] The low pressure permeate generated by the membrane separation can be used, for example, as a low carbon fuel in an appropriate burner or furnace configuration. This can assist with further decarbonizing the process for making the high purity, high pressure hydrogen stream. Alternatively, the low pressure permeate can be used as a low carbonintensity fuel for another process. It is noted that using the low pressure permeate as a fuel avoids the need to re-pressurize the permeate.

[0020] The PSA process also generates one or more tail gas streams. In some embodiments, a portion of at least one of the one or more tail gas streams can be passed into an oxycombustion process, where the composition of the tail gas provides benefits in environments where it is desirable to not introduce the substantial amount of nitrogen that is incorporated when using air as an oxygen source. The remaining H2 and CO (and / or CH4) in the tail gas is beneficial as a fuel, while the CO2 in the tail gas provides additional diluent and / or heat transport fluid for potential distribution of heat away from a combustion location.

[0021] In this discussion, unless otherwise specified, compositions of gas streams or flows are specified on a wet basis, meaning that the composition is described including the water content of the stream. When a flow or stream is described on a “dry basis”, this means that the composition of the stream is described without considering any water content.Configuration Examples

[0022] FIG. 1 shows an example of a configuration for improving the yield of recovered hydrogen when using PSA to separate hydrogen from a feed stream that has a partial pressure of hydrogen of 1.4 MPa or higher and that also contains carbon oxides. In the configuration shown in FIG. 1, a synthesis gas stream 105 (or other stream containing hydrogen and carbon oxides) is passed into optional compressor 110. Synthesis gas stream 105 can be provided from any convenient source. One option is to use a synthesis gas generated by steam reforming or another type of hydrocarbon reforming. Another option is to use a reforming output that has also been passed through a water gas shift In aspects where the initial pressure of synthesis gas stream 105 is sufficiently high, compressor 110 is not needed. In other aspects, optional compressor 110 is used to increase the pressure of synthesis gas stream 105. Increasing the pressure of the stream can improve both throughput and hydrogen recovery.

[0023] In the configuration shown in FIG. 1, the optionally compressed synthesis gas stream 115 is split into two portions. A membrane separation portion 117 is passed into membrane separation stage 120. This produces a low pressure hydrogen-containing permeate 129 and a retentate 125 that has a lower vol% of hydrogen than the membrane separation portion 117. A bypass portion 122 is not sent to membrane separation stage 120, and is instead combined with the retentate output 125 of membrane separation stage 120. The bypass portion 122 can be combined with retentate output 125 prior to and / or after entry into pressure swingadsorption stage 130. The amount of hydrogen in hydrogen-containing permeate 129 corresponds to roughly 1.0 mol% to 5.0 mol% of the hydrogen contained in optionally compressed synthesis gas stream 115. The use of a bypass flow can be beneficial for some types of membrane configurations, so that the amount of flow exposed to the membrane is reduced.

[0024] In an alternative embodiment, all of the optionally compressed synthesis gas stream 115 can be passed into membrane separation stage 120, so that a bypass stream 122 is not formed. In such an embodiment, the retentate output 125 is the stream that is passed into pressure swing adsorption stage 130.

[0025] After the membrane separation, the retentate output 125 and optionally the bypass stream 122 are passed into pressure swing adsorption stage 130. During the adsorption step, the pressure swing adsorption stage 130 produces a high purity, high pressure hydrogencontaining product 135 by adsorbing the non-hydrogen components that are passed into the pressure swing adsorption stage 130. The pressure swing adsorption stage 130 also generates one or more desorption gases, purge gases, and / or depressurization gases that are generated during the steps in the swing adsorption cycle that are used to regenerate the bed after the . In FIG. 1, these gases are represented by tail gas stream 137. Although not shown, additional steps can be performed on tail gas stream 137 to attempt to recover a portion of the hydrogen remaining in the tail gas stream 137. For example, a tail gas membrane separation (not shown) can be performed on one or more portions of the tail gas to recover part of the hydrogen. Although not shown in FIG. 1 , such a recovery stream could then be optionally compressed and added back into the synthesis gas stream 105; and / or added back into optionally compressed synthesis gas stream 115; and / or added back into bypass stream 122.

[0026] The configuration shown in FIG. 1 is generally suitable for separation of hydrogen from a synthesis gas contains any combination of carbon oxides. As an alternative to the configuration in FIG. 1, some membranes have a higher permeability to CO2 relative to CO. For such membranes, it could be advantageous to perform the membrane separation prior to any water gas shift reaction. The water gas shift reaction is typically used to drive additional production of H2, but this also converts CO into CO2. For a membrane with a higher permeability for CO2 than CO, performing the separation before performing water gas shift means that more CO is present and less CO2, thus reducing the amount of carbon oxides that are transported across the membrane.

[0027] FIG. 2 shows an example of a configuration where the initial membrane is upstream from the water gas shift reaction stage. In the configuration shown in FIG. 2, the synthesis gas stream 215, optionally after compression (not shown), is passed into membrane separation stage 220. This forms a low pressure, high hydrogen-content permeate 229 and a retentate stream 225. The retentate stream 225 is then passed into a water gas shift reaction stage 250 under conditions that favor increased formation of H2 and CO2 in place of H2O and CO. The shifted stream is then passed into pressure swing adsorption stage 230 to form the high pressure, high hydrogen-content product 235 and one or more tail gas streams 237.Synthesis Gas

[0028] A synthesis gas stream is an example of a stream that can be separated to form hydrogen-containing streams as described herein. However, it is noted that having hydrogen plus at least one carbon oxide (CO or CO2) are the only required components in the feed. Depending on the nature of the process used to form the synthesis gas stream, the synthesis gas stream may be suitable for separation after optional compression. Alternatively, if the hydrogen content of the synthesis gas stream is lower, a water gas shift stage can also be used to increase the hydrogen content of the stream prior to starting the separation process.

[0029] Various types of reforming processes are available for making a synthesis gas stream. One type of reforming is steam reforming, where hydrocarbons are reformed in the presence of steam. Another type of reforming is “dry reforming”, which is performed in the presence of CO2. Still another type of reforming is partial oxidation, where hydrocarbons are exposed to heat in the presence of a sub- stoichiometric quantity of oxygen. This results in formation of H2 and CO as partial oxidation products, in addition to the traditional combustion products of H2O and CO2. Yet another type of reforming is autothermal reforming, which involves reforming in the presence of both steam and a limited amount of oxygen. Equations 1 to 6 illustrate the basic reactions that take place during reforming of methane using the various techniques. Steam reforming is illustrated by Equations 1 and 2. Equation 3 corresponds to dry reforming. Autothermal reforming can occur according to the process in either Equation 5 or Equation 5, depending on whether an excess of CO2 or H2O is present in addition to a sub- stoichiometric amount of oxygen. Equation 6 shows an example of a possible partial oxidation reaction, but it is noted that the mix of products generated by partial oxidation varies widely depending on the amount of oxygen present. More generally, while the equations below imply a ratio of products based on stoichiometry, it is noted that the reaction conditions for each typeof reforming can result in variations in the exact amounts of H2 and CO that are generated. Of course, combinations of these reactions can also occur if the appropriate reactants are present in a reaction environment.

[0030] (1) CH4+ H2O => CO + 3H2 (Steam reforming)

[0031] (2) CO + H2O => CO2 + H2 (Steam reforming)

[0032] (3) CH4+ CO2 => 2CO + 2H2(Dry reforming)

[0033] (4) 2CH4+ O2+ CO2 => 3H2 + 3CO + H2O (Autothermal reforming)

[0034] (5) 4CH4+ O2+ 2H2O => 10 H2 + 4CO (Autotheraml reforming)

[0035] (6) CH4+ O2=> CO + H2 + H2O (Partial oxidation example - Can also formCO2, variable mix of products)

[0036] The ratio of H2 to CO in a synthesis gas generated by each type of reforming varies. The amount of water in the resulting synthesis gas also varies. Steam reforming tends to produce a synthesis gas with a H2 to CO ratio of roughly 3 : 1. However, steam reforming is typically performed using an excess of steam. Therefore, the resulting synthesis gas from steam reforming typically has a relatively high ratio of water to carbon oxides, so that the molar ratio of water to carbon oxides in the synthesis gas is 2 : 1 or higher. The configuration shown in FIG. 1 can be used to separate hydrogen from this type of synthesis gas.

[0037] By contrast, autothermal reforming and partial oxidation are examples of reforming methods that produce a synthesis gas with a lower ratio of H2O to carbon oxides. Depending on the conditions, the resulting synthesis gas can also have a lower ratio of H2 to CO. In some embodiments, a synthesis gas can be formed, such as by autothermal reforming and / or partial oxidation, that has a molar ratio of H2O to carbon oxides of 0.8 to 1.2, or 0.9 to 1.1. The H2 to CO molar ratio can also be lower, such as 2.0 or less, or 1.5 or less, such as down 1.0 or possibly still lower. For this type of synthesis gas, the configuration shown in FIG. 1 can be used by performing the water gas shift reaction, and then processing the resulting shifted synthesis gas. However, the configuration shown in FIG. 2 can also be used for this type of synthesis gas. If the configuration shown in FIG. 2 is used, a membrane with increased selectivity for rejecting CO can be used, to allow for H2 recovery while reducing or minimizing the CO content in the permeate.Input Flows, Output Flows, and Membrane Separation

[0038] In some embodiments, the input gas flow for the separation process, prior to exposure of a portion of the input gas flow to the initial membrane separation, has a hydrogencontent (wet basis) of 70 vol% or more, or 75 vol% or more, or 80 vol% or more, or 85 vol% or more, such as up to 90 vol% or possibly still higher. In addition to hydrogen, the input gas flow contains at least one carbon oxide, and optionally water. A steam reforming effluent and / or a synthesis gas that has passed through a water gas shift reaction stage are examples of this type of input gas flow. In other embodiments, such as embodiments where the input gas flow corresponds to a synthesis gas made using autothermal reforming and / or partial oxidation, the hydrogen content can be lower, such as a hydrogen content of 40 vol% or more (wet basis), or 50 vol% or more, such as up to 80 vol%. On a dry basis, the corresponding hydrogen content can be 60 vol% or more, or 70 vol% or more, such as up to 90 vol%.

[0039] The input gas flow can also contain the typical components of synthesis gas. In some embodiments, the input gas flow contains 0 vol% to 30 vol% of CO, or 1.0 vol% to 30 vol%, or 5.0 vol% to 30 vol%, or 10 vol% to 30 vol%, or 15 vol% to 30 vol%, or 0 vol% to 20 vol%, or 1.0 vol% to 20 vol%, or 5.0 vol% to 20 vol%, or 0 vol% to 10 vol%, or 1.0 vol% to 10 vol%. Additionally or alternatively, the input gas flow contains 0 vol% to 30 vol% of CO2, or 1.0 vol% to 30 vol%, or 5.0 vol% to 30 vol%, or 10 vol% to 30 vol%, or 15 vol% to 30 vol%, or 0 vol% to 20 vol%, or 1 .0 vol% to 20 vol%, or 5.0 vol% to 20 vol%, or 0 vol% to 10 vol%, or 1.0 vol% to 10 vol%. Further additionally or alternatively, the input gas flow contains 0 vol% to 30 vol% of H2O, or 1.0 vol% to 30 vol%, or 5.0 vol% to 30 vol%, or 10 vol% to 30 vol%, or 15 vol% to 30 vol%, or 0 vol% to 20 vol%, or 1.0 vol% to 20 vol%, or 5.0 vol% to 20 vol%, or 0 vol% to 10 vol%, or 1.0 vol% to 10 vol%. It is noted that in some embodiments, the water content of the input gas flow can be relatively low, so that the water content is 0 vol% to 1.5 vol%, or 0 vol% to 1.0 vol%, or 0.1 vol% to 1.5 vol%, or 0.1 vol% to 1.0 vol%.

[0040] In some embodiments, the combined content of carbon oxides in the input gas flow (wet basis) is 5.0 vol% or more, or 10 vol% or more, or 15 vol% or more, or 20 vol% or more, or 25 vol% or more, such as up to 40 vol% or possibly still higher. It is noted that a synthesis gas stream where water has been removed (such as by condensation) can allow for high contents H2 while also having 30 vol% or more of carbon oxides.

[0041] In some embodiments, methane can be present in the input gas flow. The input gas flow can contain 0% to 10 vol% of methane, or 0 vol% to 5.0 vol%, or 0 vol% to 3.0 vol%, or 0.1 vol% to 10 vol%, or 0.1 vol% to 5.0 vol%, or 0.1 vol% to 3.0 vol%.

[0042] Optionally, the input gas flow may contain small amounts of other components, such as N2 or Ar. Depending on the embodiment, the input gas flow contains 3.0 vol% or lessof N2, Ar, or a combination thereof, or 1.0 vol% or less, such as down to having substantially no content of other components.

[0043] Generally, the input gas flow can have a total pressure of 1.5 MPa-a to 7.0 MPa- а, or 1.5 MPa-a to 6.0 MPa-a, or 1.5 MPa-a to 5.0 MPa-a, or 1.5 MPa-a to 4.0 MPa-a, or 1.5 MPa-a to 3.0 MPa-a, or 1.5 MPa-a to 2.5 MPa-a, or 2.1 MPa-a to 7.0 MPa-a, or 2.1 MPa-a to б.0 MPa-a, or 2.1 MPa-a to 5.0 MPa-a, or 2.1 MPa-a to 4.0 MPa-a, or 3.0 MPa-a to 7.0 MPa- а, or 3.0 MPa-a to 6.0 MPa-a, or 3.0 MPa-a to 5.0 MPa-a, or 3.5 MPa-a to 7.0 MPa-a, or 3.5 MPa-a to 6.0 MPa-a, or 3.5 MPa-a to 5.0 MPa-a, or 4.0 MPa-a to 7.0 MPa-a, or 4.0 MPa-a to б.0 MPa-a. In addition to the total pressure, the partial pressure of hydrogen can also be characterized. In various aspects where performing the initial membrane separation provides a net increase in hydrogen recovery, the partial pressure of hydrogen in the input gas flow can be 1.4 Mpa to 6.5 MPa, or 1.4 MPa to 5.5 MPa, or 1.4 MPa to 4.5 MPa, or 1.4 MPa to 3.5 MPa, or 2.0 MPa to 6.5 MPa, or 2.0 MPa to 5.5 MPa, or 2.0 MPa to 4.5 MPa, or 2.0 MPa to 3.5 MPa, or 2.5 MPa to 6.5 MPa, or 2.5 MPa to 5.5 MPa, or 2.5 MPa to 4.5 MPa, or 3.0 MPa to 6.5 MPa, or 3.0 MPa to 5.5 MPa, or 4.0 MPa to 6.5 MPa, or 4.0 MPa to 5.5 MPa, or 4.5 MPa to 6.5 MPa.

[0044] A variety of membranes are available that are size-selective for allowing permeation of H2 while reducing or minimizing permeation of carbon oxides. Examples of membrane materials that can separate hydrogen from carbon oxides include, but are not limited to, platinum and / or palladium-based membranes; polymeric membranes, such as membranes composed of polyimide, polyaramide, cellulose acetate, and / or polysulfone; and zeolitic materials, including materials such as zeolitic imidazole frameworks (ZIFs). Optionally, the membrane material can be supported on a support layer.

[0045] Any convenient type of membrane configuration can be used. Examples of membrane configurations include, but are not limited to, spiral wound membranes, hollow fiber membranes, and tubular membranes. Although the configurations shown in FIG. 1 and FIG. 2 illustrate a single membrane, it is understood that a membrane separation stage can be used, so that the separation is performed by one or more membranes arranged serially and / or in parallel.

[0046] During the initial membrane separation, a small portion of the hydrogen in the input gas flow is separated out to form a low pressure permeate. The amount of hydrogen in the low pressure permeate corresponds to roughly 1.0 vol% to 5.0 vol% of the hydrogen in the input gas flow. Due to the relatively high purity, little or no content of other components (such as carbon oxides) are passed into the permeate. Thus, after the membrane separation stage, theinitial retentate stream plus any optional bypass stream corresponds to a gas flow with composition and pressure that is somewhat similar to the input gas flow prior to the membrane separation stage. However, for the net flow after the membrane separation stage, the hydrogen partial pressure is reduced by roughly 1.0% to 5.0%, based on the amount of hydrogen that is passed into the low pressure permeate. This also means that the total pressure of the net flow after the membrane separation stage is reduced by an amount similar to the reduction in the hydrogen partial pressure. The amount of reduction for the hydrogen partial pressure and / or for the total pressure for the net flow after the membrane separation stage can be from 0.07 MPa (70 kPa) to 0.2 MPa (200 kPa), depending on the partial pressure of hydrogen and the concentration of hydrogen in the input gas flow prior to membrane separation.

[0047] In various embodiments, the permeate formed by the membrane separation can have a hydrogen content of 85 vol% or more, or 90 vol% or more, or 95 vol% or more, such as up to 98 vol% or possibly still higher. This hydrogen content corresponds to a higher hydrogen content than the input gas flow to the membrane. The remaining 5.0 vol% to 15 vol% of the permeate corresponds to water and carbon oxides, and optionally trace gases such as N2 or Ar. Due to the nature of membrane separations, the permeate is at a pressure that is substantially below the pressure of the input gas flow. Depending on the embodiment, the pressure of the permeate is 0.09 MPa-a (90 kPa-a) to 3.0 MPa-a (1000 kPa-a), or 0.09 MPa-a to 2.0 MPa-a, or 0.09 MPa-a to 1.0 MPa-a, or 0.2 MPa-a to 3.0 MPa-a, or 0.2 MPa-a to 2.0 MPa-a, or 0.2 MPa- a to 1.0 MPa-a, or 0.5 MPa-a to 3.0 MPa-a, or 0.5 MPa-a to 2.0 MPa-a. Additionally or alternatively, the pressure of the permeate is 50% or less of the pressure of the input gas flow to the membrane, or 35% or less, or 25% or less, or 15% or less, such as down to 1.4% of the pressure of the input gas flow, or possibly still less.

[0048] In some embodiments, only a portion of the input gas flow is exposed to the initial membrane. In such aspects, the remaining portion of the input gas flow can form one or more bypass flows that are not exposed to the membrane. The bypass flow is then combined with the retentate from the initial membrane stage to form the input for the pressure swing adsorption stage. Depending on the embodiment, the portion of the input gas flow exposed to the initial membrane can correspond to 10 vol% or more of the input gas flow, or 30 vol% or more, or 50 vol% or more, or 70 vol% or more, such as up to 90 vol%. The corresponding bypass flow(s) contain 10 vol% to 90 vol% of the input gas flow, or 10 vol% to 70 vol%, or 10 vol% to 50 vol%, or 10 vol% to 30 vol%.

[0049] The temperature of the input gas flow can be any convenient temperature for performing the initial membrane separation and then the subsequent PSA separation. In some embodiments, the initial membrane separation is performed at a temperature of 20°C to 300°C, or 20°C to 200°C, or 20°C to 100°C, or 40°C to 300°C, or 40°C to 200°C. Additionally or alternatively, in various embodiments, the adsorption step of the PSA process can be performed at a temperature of 20°C to 300°C, or 20°C to 200°C, or 20°C to 100°C, or 40°C to 300°C, or 40°C to 200°C. It is noted that the temperature for the initial membrane separation stage can be selected separately from the temperature for the input to the PSA separation stage. Thus, depending on the configuration, the adsorption step of the PSA process can be performed at a temperature similar to the temperature of the retentate as the retentate exits from the membrane separation stage. Alternatively, heat exchangers can be used to adjust the temperature of the retentate (and any optional membrane bypass flow) to a different temperature prior to entering the PSA stage. As another example, in embodiments where membrane separation is followed by a water gas shift reaction stage, heaters and / or heat exchangers can be used to adjust the temperature of the retentate stream to be suitable for performing the water gas shift reaction under desired conditions for increasing the hydrogen content. The output from the water gas shift reaction stage can then be exposed to further heat exchangers to adjust the shifted input stream to a target temperature for performing the adsorption step of the PSA separation cycle.

[0050] The hydrogen-containing product generated by the pressure swing adsorption stage can correspond to a typical hydrogen-containing product. The purity of the hydrogencontaining product can be 95.0 vol% or more (dry basis), or 97.0 vol% or more, or 99.0 vol% or more, such as up to being substantially composed of hydrogen (99.9 vol% hydrogen or possibly still more). In various embodiments, the purity of the hydrogen-containing product (dry basis) from the pressure swing adsorption stage is higher than the purity of the permeate (dry basis). Due to the nature of a pressure swing adsorption process, the partial pressure of hydrogen in the hydrogen-containing product can be similar to the partial pressure of hydrogen in the input flow to the pressure swing adsorption stage. However, the total pressure in the hydrogen-containing product is typically lower than the total pressure of the input flow to the pressure swing adsorption stage, due to the removal of carbon oxides and / or water. Due to the relatively high purity of the hydrogen-containing product, the pressure of the hydrogen- containing product is typically similar to the partial pressure of hydrogen in the input flow to the pressure swing adsorption stage. Thus, in some embodiments, the pressure of the hydrogen-containing product from the pressure swing adsorption stage is 1.4 MPa-a to 6.5 MPa-a, or 1.4 MPa-a to 5.5 MPa-a, or 1.4 MPa-a to 4.5 MPa-a, or 1.4 MPa-a to 3.5 MPa-a, or 2.0 MPa-a to6.5 MPa-a, or 2.0 MPa-a to 5.5 MPa-a, or 2.0 MPa-a to 4.5 MPa-a, or 2.0 MPa-a to 3.5 MPa- a, or 2.5 MPa-a to 6.5 MPa-a, or 2.5 MPa-a to 5.5 MPa-a, or 2.5 MPa-a to 4.5 MPa-a, or 3.0 MPa-a to 6.5 MPa-a, or 3.0 MPa-a to 5.5 MPa-a, or 4.0 MPa-a to 6.5 MPa-a, or 4.0 MPa-a to5.5 MPa-a, or 4.5 MPa-a to 6.5 MPa-a.

[0051] The combined recovery of hydrogen is calculated based on the recovery of hydrogen in the permeate from the initial membrane and the recovery of hydrogen in the hydrogen-containing product from the pressure swing adsorption stage. In embodiments where the initial membrane separation is performed after any water gas shift stages, the amount of hydrogen recovery is specified relative to the amount of hydrogen present in the initial gas flow to the membrane. In embodiments where one or more water gas shift stages are present after the initial membrane separation, the amount of hydrogen recovery can be determined in a different manner. First, the amount of hydrogen recovered in the pressure swing adsorption stage is determined, along with the amount of hydrogen introduced into the pressure swing adsorption stage. Any hydrogen recovered in the membrane permeate is then added to both the amount recovered from the pressure swing adsorption stage and the amount introduced into the pressure swing adsorption stage.

[0052] In various embodiments, the combined amount of hydrogen recovered is greater than the amount of hydrogen that would be recovered in the absence of the initial membrane separation (in other words, greater than the amount that would be recovered by simply passing the input gas flow into the pressure swing adsorption stage without performing the membrane separation.) Depending on the embodiment, the combined recovery of hydrogen from the input gas flow can be 90 vol% to 99 vol%, or 92 vol% to 99 vol%, or 95 vol% to 99 vol%, or 90 vol% to 97 vol%, or 92 vol% to 97 vol%, or 90 vol% to 95 vol%. Additionally or alternatively, the combined recovery of hydrogen is greater than the amount of hydrogen that would be recovered in the absence of the membrane by 0.1 vol% or more, or 0.5 vol% or more, or 1.0 vol% or more, such as up to 2.5 vol% or possibly still more. When comparing the combined recovery with a hydrogen recovery in the absence of the membrane, the conditions for the pressure swing adsorption stage when operating without the membrane should be held constant relative to the conditions used for the pressure swing adsorption stage with the membrane. It is noted that this might slightly reduce the total throughput in the absence of the membrane, asthe membrane removes a small amount of the input gas flow prior to entering the pressure swing adsorption stage. However, the recovery is expressed relative to the amount of hydrogen in the input gas flow, so the small reduction in throughput does not impact the recovery value.

[0053] With regard to water gas shift, the input flow compositions described herein can correspond to the composition either after passing through a water gas shift stage, or prior to a water gas shift stage, or a composition between two separate water gas shift stages. In embodiments where the input flow composition corresponds to a composition prior to a water gas shift stage, the water gas shift stage can be operated under conditions to further increase the content of H2 and CO2 in the stream with a corresponding reduction in H2O and CO2.

[0054] Any convenient type of water gas shift reaction stage can be used. The catalyst used for water gas shift is partially dependent on the temperature range used for performing the water gas shift reaction. For low temperature water gas shift, copper or copper oxide catalysts are typically used. An example of a low temperature water gas shift catalyst is a catalyst including copper oxide, alumina, and zinc oxide. Low temperature water gas shift is typically performed at temperatures of 180°C to 250°C. At higher temperatures, other types of catalysts are typically used, such as catalysts based on a combination of iron oxide and chromium. Higher temperature water gas shift is typically performed at temperatures of 310°C to 450°C. Higher temperatures increase the reaction rate, but because the water gas shift reaction is exothermic, formation of hydrogen is favored at lower temperatures, while formation of CO (reverse water gas shift) is favored at higher temperatures.Pressure Swing Adsorption Stage

[0055] A variety of adsorbents can be used for separation hydrogen from carbon oxides. Some adsorbents correspond to materials that have a zeolitic framework structure, referred to herein as zeolites. In this discussion, a zeolite is defined to refer to a crystalline material having a porous framework structure built from tetrahedra atoms connected by bridging oxygen atoms. Examples of known zeolite frameworks are given in the “Atlas of Zeolite Frameworks” published on behalf of the Structure Commission of the International Zeolite Association”, 6threvised edition, Ch. Baerlocher, L.B. McCusker, D.H. Olson, eds., Elsevier, New York (2007) and the corresponding web site, http: / / www. Under this definition,a zeolite can refer to aluminosilicates (i.e., zeolites) having a zeolite framework structure as well as crystalline structures containing oxides of heteroatoms different from silicon and aluminum. Such heteroatoms can include any heteroatom generally known to be suitable forinclusion in a zeotype framework, such as gallium, boron, germanium, phosphorus, zinc, and / or other transition metals that can substitute for silicon and / or aluminum in a zeotype framework. It is noted that under this definition, a zeotype can include materials such as silicoaluminophosphate (SAPO) materials or aluminophosphate (A1P0) materials.

[0056] In this discussion, a siliceous zeolite is defined as a crystalline material including both silicon and aluminum as atoms in the framework structure, wherein the silicon to aluminum ratio for the framework structure is 70 or more, or optionally 100 or more, such as up to 600 or possibly still higher. More generally, a zeolite can have a silicon to aluminum ratio of 3 or more, or 10 or more, or 30 or more.

[0057] Pressure swing adsorption (PSA) is typically performed using a plurality of sorbent beds working in conjunction to provide a continuous process for separating hydrogen from a pyrolysis effluent. Any convenient type of adsorbent suitable for use in a pressure swing adsorption (PSA) process can be used. An example of a suitable PSA adsorbent is a packed bed of sorbent particles. The particles can be composed entirely of a sorbent material, or the particles can correspond to a sorbent material supported on a support. Alternatively, a monolith structure can be used, such as a monolith coated with a sorbent material or a monolith formed from a sorbent material.

[0058] Pressure swing adsorption (PSA) relies on swinging or cycling pressure over a bed of adsorbent through a range of values. In PSA processes, a gaseous mixture is conducted under pressure for a period of time over a first bed of a solid sorbent that is selective, or relatively selective, for one or more components, usually regarded as a contaminant, to be removed from the gaseous mixture. For example, a feed can be introduced into a PSA apparatus at a feed pressure. At the feed pressure, one or more of the components (gases) in the feed can be selectively (or relatively selectively) (ad)sorbed, while one or more other components (gases) can pass through with lower or minimal adsorption. A component (gas) that is selectively (ad)sorbed can be referred to as a “heavy” component of a feed, while a gas that is not selectively (ad)sorbed can be referred to as a “light” component of a feed. For convenience, a reference to the “heavy” component of the feed can refer to all components (gases) that are selectively (ad)sorbed, unless otherwise specified. Similarly, a reference to the “light” component can refer to all components (gases) that are not selectively (ad)sorbed, unless otherwise specified. After a period of time, the feed flow into the PSA apparatus can be stopped. The feed flow can be stopped based on a predetermined schedule, based on detectionof breakthrough of one or more heavy components, based on (ad)sorption of the heavy component(s) corresponding to at least a threshold percentage of the total capacity of the (ad)sorbent, or based on any other convenient criteria. The pressure in the reactor can then be reduced to a desorption pressure that can allow the selectively (ad)sorbed component(s) (gas(es)) to be released from the (ad)sorbent. Optionally, one or more purge gases can be used prior to, during, and / or after the reduction in pressure to facilitate release of the selectively (ad)sorbed component(s) (gas(es)). Depending on its nature, a full PSA cycle can optionally be performed at a roughly constant temperature. As PSA is usually enabled by at least adsorption and usually occurs on gaseous components, the terms “adsorption’7“adsorbent” and “gas(es)” are used as descriptors in the instant specification and claims, without intending to be limiting in scope, even though “absorption’7“absorbent’7“sorbent’7“sorption” and “component(s)” may be more generally applicable.

[0059] Multiple beds can be used to enable a complete cycle, where typically every bed sequentially goes through the same cycle. When a first PSA reactor satisfies a condition, such as the adsorbent in the reactor becoming sufficiently saturated, the feed flow can be switched to a second reactor. The first PSA reactor can then be regenerated by having the adsorbed gases released. To allow for a continuous feed flow, a sufficient number of PSA reactors and / or adsorbent beds can be used so that the first PSA reactor is finished regenerating prior to at least one other PSA reactor satisfying the condition for switching reactors.

[0060] In various emodiments, a PS A reactor can be used for performing a separation on a stream containing H2 and at least one of CO and CO2. Synthesis gas is an example of such a stream. When exhaust stream is introduced into the PSA stage, the H2in the exhaust stream corresponds to a “light” component while the carbon oxides correspond to “heavy” components. Thus, the H2 can primarily pass through the reactor while the carbon oxides can be selectively adsorbed within the reactor. The adsorption of carbon oxides from the feed results in a product hydrogen-containing stream. For a PSA stage that is designed to operate continuously, the feed can be passed through a first PSA reactor (or a plurality of first PSA reactors) until one or more pre-defined criteria are satisfied for switching the feed to another PSA reactor (or second plurality of PSA reactors) or otherwise stopping the flow of feed gas. Any convenient pre-defined criteria can be used. For example, the feed can be passed through the reactor for a specified time period. Additionally or alternatively, the feed can be passed into the reactor until a breakthrough amount of CO and / or CO2 is detected in the product H? stream.Further additionally or alternatively, the feed can be passed into the reactor until the amount of CO and / or CO2 that has entered the reactor is approximately equal to a threshold value of the adsorbent capacity of the reactor. In such a situation, for example, the feed can be passed into the reactor until the amount of CO and / or CO2 that has entered the reactor is equal to at least about 75% of the adsorbent capacity of the adsorbent material in the reactor, such as at least about 80%, at least about 85%, or at least about 90%. The adsorption I product formation step of a typical PSA cycle can involve introducing feed into a reactor for 5 seconds to 100 seconds, or 10 seconds to 50 seconds. The total cycle length, including various desorption, purge, and / or re-pressurization steps, can be from 20 seconds to 250 seconds, or 20 seconds to 150 seconds, or 40 seconds to 250 seconds, or 40 seconds to 150 seconds.

[0061] After the feed for the adsorption step is stopped, a series of steps can be performed to regenerate the adsorbent bed while attempting to reduce or minimize the amount of hydrogen that is lost. The steps can be any combination of blowdown steps, desorption steps, purge steps, pressurization steps, and / or any other type of step that is conventionally included in a PSA process. The exact nature of the PSA process is not critical, as the benefit of performing the initial membrane separation is achieved independent of the PSA process, so long as the hydrogen partial pressure is sufficiently high.

[0062] It is noted that the temperature and pressure of the steps other than the adsorption step in the PSA cycle can differ from the conditions during the adsorption step. With regard to pressure, part of the goal of a PSA process is to use large variations in pressure to rapidly transition from adsorption to desorption. Thus, for the blowdown, desorption, purge, and / or some repressurization steps in a PSA cycle, the pressure is lower than the pressure for the adsorption step that forms the hydrogen-containing product. In some embodiments, one or more of the steps of the PSA cycle can be performed at a pressure near ambient, such as a pressure of 90 kPa-a to 110 kPa-a. More generally, the pressure of one or more of the steps different from the adsorption step can be 90 kPa-a to 500 kPa-a (0.5 MPa-a), or 90 kPa-a to 300 kPa-a, or 90 kPa-a to 150 kPa-a, or 90 kPa-a to 110 kPa-a, or 110 kPa-a to 500 kPa-a, or 110 kPa-a to 300 kPa-a, or 150 kPa-a to 500 kPa-a, or 150 kPa-a to 300 kPa-a.

[0063] A wide variety of adsorbents can be used for the adsorbent bed in the PSA process. Examples of suitable adsorbents include zeolite adsorbents, including both silicoaluminate zeolitic framework structures as well as zeolitic framework structures containing framework atoms different from silicon, aluminum, and oxygen; metal-organic framework adsorbents;amine-based sorbents; and / or any other convenient adsorbent that has selectivity for adsorption of carbon oxides relative to hydrogen.Additional Embodiments

[0064] Embodiment 1. A method for separating hydrogen from an input gas stream containing hydrogen and at least one carbon oxide, comprising: providing an input gas stream comprising 70 vol% or more of H2 on a dry basis and at least one of CO and CO2, the input gas stream having a partial pressure of H2 of 1 .4 MPa or higher; performing a membrane separation on at least a portion of the input gas stream to form a permeate comprising 1.0 vol% to 5.0 vol% of the H2 present in the input gas stream and a retentate; and passing a swing adsorption input stream comprising at least a portion of the retentate into a pressure swing adsorption stage to form a hydrogen-containing product and at least one tail gas stream, the hydrogen-containing product having an H2 content of 95 vol% or more, the swing adsorption input stream having a total pressure of 1.5 MPa-a or higher, wherein the combined H2 content of the permeate and the hydrogen-containing product correspond to a recovery of 90 mol% or more of the H2 in the input gas stream.

[0065] Embodiment 2. The method of Embodiment 1 , wherein the input gas stream has a molar ratio of H2 to CO of 2.5 or higher.

[0066] Embodiment 3. The method of any of the above embodiments, the method further comprising passing the retentate into a water gas shift stage to form a shifted retentate, the swing adsorption input stream comprising at least a portion of the shifted retentate.

[0067] Embodiment 4. A method for separating hydrogen from an input gas stream containing hydrogen and at least one carbon oxide, comprising: providing an input gas stream comprising H2, CO, CO2, and H2O, the input gas stream having 60 vol% or more of H2 on a dry basis and having a partial pressure of H2 of 1.4 MPa or higher, a molar ratio of water to carbon oxides in the input gas stream being 1.2 or less; performing a membrane separation on at least a portion of the input gas stream to form a permeate comprising H2 present in the input gas stream and a retentate; passing the retentate into a water gas shift stage to form a shifted retentate; and passing a swing adsorption input stream comprising at least a portion of the shifted retentate into a pressure swing adsorption stage to form a hydrogen-containing product and at least one tail gas stream, the hydrogen-containing product having an H2 content of 95 vol% or more on a dry basis, the swing adsorption input stream having a total pressure of 1.5 MPa-a or higher, wherein the at least a portion of the shifted retentate comprises 70 vol% ormore of H2 on a dry basis, and wherein the combined H2 content of the permeate and the hydrogen-containing product correspond to a recovery of 90 mol% or more of the H2 in the input gas stream.

[0068] Embodiment 5. The method of Embodiment 4, i) wherein the input gas stream comprises a molar ratio of H2 to CO of 2.0 or less, ii) wherein the input gas stream comprises an autothermal reforming effluent, a partial oxidation effluent, or iii) a combination of i) and ii).

[0069] Embodiment 6. The method of any of the above embodiments, wherein the input gas stream comprises a total pressure of 3.0 MPa-a to 7.0 MPa-a, or wherein the input gas stream comprises a hydrogen partial pressure of 2.1 MPa or higher, or a combination thereof.

[0070] Embodiment 7. The method of any of the above embodiments, wherein the input gas stream comprises 0 - 30 vol% of H2O, 0 - 30 vol% of CO2, 0 - 30 vol% of CO.

[0071] Embodiment 8. The method of any of the above embodiments, wherein the input gas stream comprises H2, H2O, CO2, and CO.

[0072] Embodiment 9. The method of any of the above embodiments, further comprising separating the input gas stream to form at least a membrane input stream and a bypass stream, wherein performing a membrane separation on at least a portion of the input gas stream comprises performing a membrane separation on the membrane input stream, and wherein the swing adsorption stream comprises the bypass stream and the at least a portion of the retentate stream.

[0073] Embodiment 10. The method of any of the above embodiments, wherein the permeate stream comprises 85 vol% to 98 vol% of H2 on a dry basis, the H2 content of the permeate stream being higher than the H2 content of the input gas flow; or wherein the permeate stream comprises a pressure of 0.09 MPa-a to 0.5 MPa-a; or a combination thereof.

[0074] Embodiment 11. The method of any of the above embodiments, wherein the input gas stream comprises 10 vol% to 30 vol% of CO2.

[0075] Embodiment 12. The method of any of the above embodiments, wherein the input gas stream comprises 5.0 vol% to 30 vol% of CO.

[0076] Embodiment 13. The method of any of the above embodiments, wherein the input gas stream comprises 0.1 vol% to 5.0 vol% of CH4, or wherein the input gas stream comprises 3.0 vol% or less of N2, or a combination thereof.

[0077] While the present invention has been described and illustrated by reference to particular embodiments, those of ordinary skill in the art will appreciate that the invention lends itself to variations not necessarily illustrated herein. For this reason, then, reference should be made solely to the appended claims for purposes of determining the true scope of the present invention.

Claims

1. CLAIMS1. A method for separating hydrogen from an input gas stream containing hydrogen and at least one carbon oxide, comprising: providing an input gas stream comprising 70 vol% or more of H2 on a dry basis and at least one of CO and CO2, the input gas stream having a partial pressure of H2 of 1.4 MPa or higher; performing a membrane separation on at least a portion of the input gas stream to form a permeate comprising 1.0 vol% to 5.0 vol% of the H2 present in the input gas stream and a retentate; and passing a swing adsorption input stream comprising at least a portion of the retentate into a pressure swing adsorption stage to form a hydrogen-containing product and at least one tail gas stream, the hydrogen-containing product having an H2 content of 95 vol% or more, the swing adsorption input stream having a total pressure of 1.5 MPa-a or higher, wherein the combined H2 content of the permeate and the hydrogen-containing product correspond to a recovery of 90 mol% or more of the H2 in the input gas stream.

2. The method of claim 1 , wherein the input gas stream has a molar ratio of H2 to CO of 2.5 or higher.

3. The method of any of the above claims, the method further comprising passing the retentate into a water gas shift stage to form a shifted retentate, the swing adsorption input stream comprising at least a portion of the shifted retentate.

4. A method for separating hydrogen from an input gas stream containing hydrogen and at least one carbon oxide, comprising: providing an input gas stream comprising H2, CO, CO2, and H2O, the input gas stream having 60 vol% or more of H2 on a dry basis and having a partial pressure of H2 of 1.4 MPa or higher, a molar ratio of water to carbon oxides in the input gas stream being 1.2 or less; performing a membrane separation on at least a portion of the input gas stream to form a permeate comprising H2 present in the input gas stream and a retentate; passing the retentate into a water gas shift stage to form a shifted retentate; and passing a swing adsorption input stream comprising at least a portion of the shifted retentate into a pressure swing adsorption stage to form a hydrogen-containing product and at least one tail gas stream, the hydrogen-containing product having an H2 content of 95 vol% or more on a dry basis, the swing adsorption input stream having a total pressure of 1.5 MPa-a or higher, wherein the at least a portion of the shifted retentate comprises 70 vol% or more of H2 on a dry basis, and wherein the combined H2 content of the permeate and the hydrogen-containing product correspond to a recovery of 90 mol% or more of the H2 in the input gas stream.

5. The method of claim 4, i) wherein the input gas stream comprises a molar ratio of H2 to CO of 2.0 or less, ii) wherein the input gas stream comprises an autothermal reforming effluent, a partial oxidation effluent, or iii) a combination of i) and ii).

6. The method of any of the above claims, wherein the input gas stream comprises a total pressure of 3.0 MPa-a to 7.0 MPa-a, or wherein the input gas stream comprises a hydrogen partial pressure of 2.1 MPa or higher, or a combination thereof.

7. The method of any of the above claims, wherein the input gas stream comprises 0 - 30 vol% of H2O, 0 - 30 vol% of CO2, 0 - 30 vol% of CO.

8. The method of any of the above claims, wherein the input gas stream comprises H2, H2O, CO2, and CO.

9. The method of any of the above claims, further comprising separating the input gas stream to form at least a membrane input stream and a bypass stream, wherein performing a membrane separation on at least a portion of the input gas stream comprises performing a membrane separation on the membrane input stream, and wherein the swing adsorption stream comprises the bypass stream and the at least a portion of the retentate stream.

10. The method of any of the above claims, wherein the permeate stream comprises 85 vol% to 98 vol% of H2 on a dry basis, the H2 content of the permeate stream being higher than the H2 content of the input gas flow; or wherein the permeate stream comprises a pressure of 0.09 MPa-a to 0.5 MPa-a; or a combination thereof.

11. The method of any of the above claims, wherein the input gas stream comprises 10 vol% to 30 vol% of CO2.

12. The method of any of the above claims, wherein the input gas stream comprises 5.0 vol% to 30 vol% of CO.

13. The method of any of the above claims, wherein the input gas stream comprises 0.1 vol% to 5.0 vol% of CH4, or wherein the input gas stream comprises 3.0 vol% or less of N2, or a combination thereof.

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