Hydrogen production using membrane reformers

Abstract

A system and method for producing hydrogen from hydrocarbons and steam includes a membrane reformer having a plurality of membrane reactors, each having a tubular membrane. The bore of the tubular membrane is a hydrogen permeate side. The region outside the tubular membrane is a carbon dioxide retentate side. A sweep gas flows through the bore to move hydrogen in a direction counter to the flow of hydrocarbons and steam in the region outside the tubular membrane. The method includes the steps of using the sweep gas to discharge hydrogen as permeate from the bore and discharging carbon dioxide from the region outside the tubular membrane as retentate from the membrane reactor.

Description

[Technical Field]

[0001] [Priority Claim] This application claims priority to U.S. Patent Application No. 16 / 905,798, filed June 18, 2020, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to reforming hydrocarbons to produce hydrogen. [Background technology]

[0003] Hydrogen can be produced from fossil fuels. Hydrogen is commercially produced, for example, by hydrocarbon reforming or water electrolysis. Hydrogen is produced by coal gasification, biomass gasification, water electrolysis, or reforming or partial oxidation of natural gas or other hydrocarbons. The produced hydrogen can be a feedstock for chemical or electrochemical processes such as fuel cells, ammonia production, aromatization, hydrodesulfurization, and hydrocarbon hydrogenation or hydrocracking.

[0004] Natural gas reforming is the most common source of hydrogen production. Bulk hydrogen is typically produced by steam reforming of natural gas (methane). Conventional steam reforming involves heating natural gas (e.g., between 700°C and 1100°C) in the presence of steam and a nickel catalyst. This endothermic reaction produces carbon monoxide and hydrogen. The carbon monoxide gas can undergo a water-gas shift reaction to produce additional hydrogen. Summary of the Invention

[0005] One embodiment relates to a membrane reformer for producing hydrogen. The membrane reformer includes multiple membrane reactors. Each membrane reactor includes: (1) a feed conduit as the outer conduit of the membrane reactor, which receives hydrocarbons and steam into a region outside a tubular membrane within the feed conduit; (2) a catalyst (including a steam reforming catalyst) disposed in a region within the feed conduit outside the tubular membrane for converting the hydrocarbons to hydrogen and carbon dioxide; and (3) a tubular membrane within the feed conduit, which diffuses hydrogen from the region through the tubular membrane to a bore in the tubular membrane. This region is the retentate side of the tubular membrane, and discharges a retentate containing carbon dioxide. The bore is the permeate side of the tubular membrane, and discharges a permeate containing hydrogen. Each membrane reactor has an insert tube disposed within the bore to facilitate the flow of a sweep gas through the bore in a countercurrent direction to the flow of hydrocarbons and steam in the region outside the tubular membrane.

[0006] Another aspect relates to a method for producing hydrogen, comprising supplying hydrocarbons and steam to a membrane reformer having a plurality of membrane reactors. The method includes converting the hydrocarbons to hydrogen and carbon dioxide via a catalyst (including a steam reforming catalyst) disposed on the exterior of tubular membranes in the plurality of membrane reactors. The method includes diffusing hydrogen through the tubular membranes in the plurality of membrane reactors into respective bores of the tubular membranes. The method includes flowing a sweep gas through each bore to move the hydrogen countercurrently to the flow of the hydrocarbons and steam on the exterior of the tubular membranes. The method includes using the sweep gas to discharge hydrogen as a permeate from each bore and discharging carbon dioxide as a retentate from the plurality of membrane reactors to the exterior of the tubular membranes.

[0007] Yet another aspect is a method for producing hydrogen. The method includes producing hydrogen using a membrane reformer having a plurality of membrane reactors. Each membrane reactor has an outer tube and a tubular membrane within the outer tube. Hydrogen production in each membrane reactor includes (1) converting hydrocarbons to hydrogen and carbon dioxide in the presence of steam in a region within the outer tube outside the tubular membrane via a catalyst (including a reforming catalyst) disposed within the region; (2) diffusing hydrogen from the region through the tubular membrane and into a bore of the tubular membrane, the region being on the retentate side of the tubular membrane and the bore being on the permeate side of the tubular membrane; (3) venting carbon dioxide from the region; (4) flowing a sweep gas through the bore to displace hydrogen from within the bore in a direction counter to the flow of hydrocarbons within the region outside the tubular membrane; and (5) venting the hydrogen and sweep gas from the bore.

[0008] The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features and advantages will become apparent from the description and drawings, and from the claims. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram of a membrane reactor. [Figure 2] FIG. 2 is a diagram of a membrane reactor. [Figure 3] FIG. 3 is a diagram of a membrane reactor. [Figure 4] FIG. 4 is a diagram of a membrane reactor. [Figure 5] FIG. 5 is a diagram of a membrane reactor.

[0010] [Figure 6] FIG. 6 is a diagram of a tubular membrane.

[0011] [Figure 7] FIG. 7 is a diagram of a membrane reformer. [Figure 8] FIG. 8 is a diagram of a membrane reformer. [Figure 9] FIG. 9 is a diagram of a membrane reformer. [Figure 10] FIG. 10 is a diagram of a membrane reformer. [Figure 11] FIG. 11 is a diagram of a membrane reformer.

[0012] [Figure 12] FIG. 12 is a diagram of the feed interface of the membrane reformer.

[0013] [Figure 13] FIG. 13 is a diagram of the interconnection interface in a membrane reformer.

[0014] [Figure 14] FIG. 14 is a diagram of a membrane reformer. [Figure 15] FIG. 15 is a diagram of a membrane reformer. [Figure 16] FIG. 16 is a diagram of a membrane reformer. [Figure 17A] FIG. 17A is a diagram of a membrane reformer. [Figure 17B] FIG. 17B is a diagram of a membrane reformer.

[0015] Like reference numbers and designations in the various drawings indicate like elements. DETAILED DESCRIPTION OF THE INVENTION

[0016] A common large-scale route for producing hydrogen is steam methane reforming (SMR) of natural gas at high temperatures (e.g., 800°C to 900°C) and pressures (e.g., 15 bar to 40 bar) over nickel-based catalysts in alloy tubes within a furnace. This conventional SMR is typically optimized for large-scale hydrogen production and generally cannot be effectively scaled down for small-scale hydrogen production. Furthermore, the efficiency of large-scale industrial SMR processes depends on converting waste heat from the furnace exhaust into steam for use in other areas of the plant or facility. As such, scaling down for applications that do not use the generated waste heat makes the process more inefficient. In this example, the waste heat is dissipated, often with more energy-consuming active cooling.

[0017] Some aspects of the present disclosure are directed to steam reforming with hydrogen separation through a hydrogen-selective membrane as a permeate under pressure leaving a retentate. The retentate contains primarily CO and may include water vapor, unconverted methane, CO, and residual hydrogen. Thus, the process can be hydrogen production by steam reforming and hydrogen separation and CO capture via a high-temperature hydrogen membrane.

[0018] Accordingly, embodiments are directed to a catalytic membrane reactor having a hydrogen-selective membrane for producing hydrogen. The catalytic membrane reactor can be used as a modular unit in a module of multiple catalytic membrane reactors in an overall membrane reformer.

[0019] Hydrogen-selective membranes can facilitate increased hydrogen yield and recovery from equilibrium-limited reactions, such as steam methane reforming. Membrane reactors can operate at lower temperatures and be more compact than conventional SMR systems. The use of hydrogen-selective membranes facilitates the production of relatively pure hydrogen and a concentrated, capture-ready carbon dioxide stream for utilization or sequestration. Membrane reactors (membrane reformers) can reform methane (natural gas) or liquid hydrocarbon feeds to produce high-purity hydrogen while separating CO2. Membrane reactors can include a hydrogen-selective membrane (e.g., palladium or a palladium alloy) along with a highly active steam reforming catalyst. Membrane reactors can operate at operating conditions of 450°C to 600°C and 10 bar to 50 bar, compared to operating conditions of 850°C to 900°C and 10 bar to 40 bar in conventional steam reforming processes. In implementation, membrane reformers have significantly higher efficiency in producing hydrogen compared to conventional SMRs, while also having lower capital and operating costs.

[0020] The feed gas can be a pressurized mixture of steam and hydrocarbons fed into a space within the reactor outside the tubular membrane. This space can be the reaction space. This space can be the retentate side or the high-pressure side of the membrane. Hydrocarbons can include, for example, methane, liquefied petroleum gas (LPG), a C1-C6 mixture, etc. The feed gas enters the space outside the membrane and reacts to produce hydrogen, which is then drawn from the reaction space through the membrane to the permeate side (low-pressure side). A pressurized carbon dioxide-rich stream produced on the retentate side of the membrane can facilitate carbon dioxide capture. A sweep gas (such as steam or nitrogen) can be used to increase the driving force for hydrogen permeation through the membrane. The sweep gas can be supplied to the membrane lumen using a tube inside the membrane tube (see, for example, Figures 3-5 and 7). The sweep gas can be supplied to flow through the lumen in a direction counter to the flow of the reactants (hydrocarbon and steam) outside the tubular membrane to provide a greater driving force for hydrogen permeation.

[0021] The catalyst in the membrane reactor may be in the form of pellets or granules, or may be disposed in a metal foam. The catalyst may be a washcoat on the inner surface of the reactor tubular vessel. In this implementation, the catalyst does not contact the membrane, thereby avoiding deactivation or surface scratching of the membrane material and promoting the life of the membrane material (e.g., palladium alloy). The gap (distance) between the catalyst and the membrane may be relatively small to facilitate diffusion of hydrogen (produced by the reaction) through the membrane.

[0022] 1 is a catalytic membrane reactor 100 for steam reforming of hydrocarbons (e.g., natural gas or methane) to produce hydrogen. The catalytic membrane reactor 100 may be classified as a catalytic membrane reformer. For clarity, the right-hand portion of the reactor 100 is shown. The left-hand portion (not shown) mirrors the right-hand portion.

[0023] The reactor 100 has a hydrogen-selective tubular membrane 102 within a feed tube 104 (feed conduit). An annulus 106 is a reaction space for the reforming reaction and is on the retentate side of the tubular membrane 102. A reforming catalyst 108 is disposed on the inner surface of the feed tube 104. The feed tube 104 may be the outer tube (outer conduit) of the reactor 100. The outer surface of the feed tube 104 may be the outer surface of the reactor 100.

[0024] The reactor 100 can include a heat source 110 to provide heat for the endothermic reforming reaction. For example, the heat source 110 can be an electric heater disposed on the exterior surface of the supply tube 104. The heat source 110 can be the supply tube 104 via an electric current flowing through the supply tube 104 for electrical resistance heating. In some examples, the heat source 110 can be an electric resistance heater (e.g., an electric cartridge heater) disposed as an internal heater within the annulus 106.

[0025] During operation, a feed 112 is provided to the annulus 106. The feed may include hydrocarbons (e.g., methane) and steam (H2O). In the annulus 106, the hydrocarbons are converted to hydrogen (H2) and carbon dioxide (CO2) by reforming over the catalyst 108. The reforming catalyst 108 may further include a water-gas shift (WGS) catalyst to facilitate the conversion of carbon monoxide (CO) formed in a water-gas shift reaction in the annulus 106 to CO2 and H2.

[0026] The produced hydrogen 114 can diffuse through the wall (membrane material) of the tubular membrane 102 into the bore 118 (lumen) of the tubular membrane 102 as hydrogen permeate 116. The bore 118 is the permeate side of the tubular membrane 102. In implementations, the operating pressure of the annulus is in the range of 10 bar to 50 bar. The unit "bar" as used herein refers to bar absolute pressure (bar). The residue 120 (e.g., primarily CO2) can be exhausted from the annulus 106. In implementations, a sweep gas 122 (e.g., steam or nitrogen) is introduced (flowed) into the bore 118 to displace the hydrogen permeate 116. The operating pressure of the bore 118 (permeate side of the membrane 102) and the flowing sweep gas 122 can be maintained, for example, in the range of 1 bar to 5 bar, or in the range of 2 bar to 3 bar, or below 3 bar. Countercurrent flow of the sweep gas 122 against the retentate 120 to displace the permeate 116 can drive diffusion of hydrogen 114 through the wall of the membrane 102 as the permeate 116 (increasing the driving force for permeation) into the bore 118. The hydrogen product 124, including the hydrogen permeate 116 and the sweep gas 122, can exit the bore 118. In the case of the sweep gas 122 as a vapor, the vapor can be easily removed from the hydrogen product 124, typically via condensation of the vapor to liquid water via a downstream condenser (e.g., a heat exchanger).

[0027] In a pilot plant example, a single-tube membrane reactor achieved greater than 90% methane to hydrogen conversion at reactor operating temperatures ranging from 500°C to 575°C (e.g., about 550°C). Adding a second membrane in series within the same reactor (downstream of the first membrane) can increase methane to hydrogen conversion rates to approach 100% (e.g., at least 98%, at least 99%, or at least 99.5% conversion). The addition of a second membrane was also beneficial in providing further purification of carbon dioxide in the residue by extracting substantially all of the remaining hydrogen from the residue.

[0028] The membrane reactor produces hydrogen through steam reforming and simultaneously separates the hydrogen (as a permeate). The membrane reactor produces CO through steam reforming and separates the CO in situ (as a membrane residue). The steam reforming reaction can include at least CH4 + H2O = CO + 3H2. In addition to steam reforming, the WGS reaction [CO + H2O = CO2 + H2] can also be involved in the membrane reactor in the production of CO2 and H2. The WGS reaction is a reversible shift reaction that is mildly exothermic. Conditions in the present membrane reactor that can be beneficial for WGS include: (a) the conversion of hydrocarbons to CO and H2 is generally high in the reforming reaction; (b) H2O is used in the conversion, and most of the H2 is removed (no thermodynamic conversion limit); and (3) the WGS reaction rate is rapid at high temperatures (above 320 °C), and the WGS conversion of CO can generally occur at a faster rate in a membrane reactor than in a conventional catalytic reactor.

[0029] Figure 2 shows a membrane reformer implementation in which a hydrogen-selective membrane is integrated with a reforming catalyst bed. The hydrogen-selective membrane facilitates continuous removal of hydrogen as it is being produced. The simultaneous production and separation of hydrogen eliminates or reduces thermodynamic equilibrium limitations. The reaction can occur at lower temperatures (e.g., 500°C to 600°C) compared to temperatures in conventional steam reforming (e.g., 850°C to 950°C). This implementation can provide process intensification by combining reaction, separation, and purification (e.g., initial purification) in a single unit (membrane reactor).

[0030] The CO produced in the reforming process can be converted to CO in a membrane reforming reactor. Through process intensification, the WGS reaction can also occur in the membrane reformer. With excess H2O, the overall reaction proceeds to CO2 and H2 (e.g., via CH4 + 2H2O = CO2 + 4H2), and the WGS reaction converts CO + H2O = CO2 + H2 in the membrane reformer.

[0031] In implementation, membrane reformers can be configured to be more compact and efficient than conventional SMR processes. Another advantage of membrane reformer systems can be the typically high concentration of CO2 in the residue (as high as 90 mole % on a dry basis), which can reduce the energy and cost penalties associated with CO2 capture.

[0032] 2 is a simplified perspective view of a catalytic membrane reactor 200 (reformer) including a feed tube 202 (feed conduit) and a hydrogen-selective tubular membrane 204 (membrane tube) disposed (e.g., concentrically) within the feed tube 202. The reactor 200 can therefore be characterized as having a tube-in-tube configuration. The feed tube 202 may be similar to the feed tube 104 described with respect to FIG. 1. The tubular membrane 204 may be similar to the tubular membrane 102 described with respect to FIG. 1.

[0033] Feed pipe 202 may be a conduit or pipe that is the outer conduit or outer pipe of reactor 200. Feed pipe 202 may be classified as a cylindrical or tubular reactor vessel. Feed pipe 202 may be a pipe (tubular conduit) that has an internal pressure rating according to applicable industry standards. Feed pipe 202 may have a horizontal orientation (as shown) or a vertical orientation.

[0034] The tubular membrane 204 can share a longitudinal or central axis with the feed pipe 202, as shown. The tubular membrane 204 can be arranged concentrically within the feed pipe 202, as shown. Other configurations are also possible. The membrane reactor 200 can have multiple tubular membranes 204 arranged within the feed pipe 202. For example, multiple tubular membranes 204 can be arranged side-by-side (sharing the same longitudinal axis) within the feed pipe 202.

[0035] The membrane material of the tubular membrane 204 may be, for example, palladium or a palladium alloy. The selectivity of the membrane 204 for hydrogen is typically greater than 1000 (dimensionless - ratio of the same parameter), where selectivity is the ratio of the hydrogen flux to the flux of another gas, e.g., nitrogen (N), through the membrane 204. The hydrogen-selective tubular membrane 204 has a hydrogen-selective capacity of at least 250 standard cubic feet per hour per square foot (SCFH / ft ) at a pressure differential (ΔP) of 100 pounds per inch (psi). 2 The hydrogen selectivity may be a flux ratio of at least 50 at 300° C. and a transmembrane pressure of 5 bar.

[0036] The supply tube 202 may be, for example, stainless steel. Other materials of construction are also applicable. In embodiments in which the wall of the supply tube 202 is an electrical resistance heater, the supply tube 202 may be of a metallurgy other than stainless steel, as described below.

[0037] During operation, hydrocarbons 206 and steam 208 are supplied to the feed tube 202. The supply may be introduced into a region 210 within the feed tube 202, which may include an annulus between the wall of the feed tube 202 and the tubular membrane 204. The hydrocarbons 206 are subjected to steam reforming within the feed tube 202 over a catalyst 209 to produce hydrogen and carbon dioxide within the feed tube 202. The catalyst 209 includes a reforming catalyst. In some implementations, steam reforming can produce primarily synthesis gas (CO and H). The water-gas shift reaction in the presence of steam converts CO to CO and H. The higher the stoichiometry of water or steam supplied to the reforming reactor 200, the more directly the overall reaction can go to CO and H, with intervening CO being produced under some conditions.

[0038] In one specific implementation, the catalyst 209 in the membrane reforming reactor 200 includes a layered catalyst having a steam reforming catalyst and a water-gas shift reaction catalyst. With this layered catalyst and lower operating temperatures (e.g., compared to conventional SMR), the water-gas shift reaction has higher equilibrium conversions (and is a mildly exothermic reaction): CH4 + HO = CO + 3H2 and CO + HO = CO2 + H2, giving the overall reaction CH4 + 2H2O = CO2 + 4H2. For catalyst 209, the reforming catalyst and optional WGS catalyst may each be nickel, nickel-based, noble metal, noble metal-based, transition metal, or transition metal-based.

[0039] The steam reforming reaction (including any water gas shift reaction) occurs in region 210 within the feed tube 202, external to the tubular membrane 104. This region 210 can be classified as the reaction space and is on the retentate side of the tubular membrane 204. References to a "steam reforming reaction" in the present membrane reactor 200 can be understood to include the conversion of CO to CO2 in certain circumstances.

[0040] As the steam reforming reaction occurs and hydrogen is formed, the hydrogen diffuses 211 (permeates) through the wall of the tubular membrane 204 into the bore of the tubular membrane 204. The wall of the tubular membrane 204 is the membrane, i.e., the membrane material (e.g., palladium or a palladium alloy). The bore is the interior space of the tubular membrane 204 and may also be classified as the lumen. The bore of the tubular membrane 204 is the permeate side of the tubular membrane 204. This process intensification in the same unit (reactor 200) includes the catalytic reaction to produce hydrogen, the separation of hydrogen from carbon dioxide through the membrane 204, and the purification of the hydrogen by separation through the membrane 204.

[0041] A hydrogen-rich permeate 212 exits the bore of the tubular membrane 204. The permeate 212 may be, for example, at least 90 mole percent (mol%) hydrogen, at least 99.99 mol%, or at least 99.999 mol%. If a sweep gas is used, these reported mole percentages of the permeate 112 (exiting the bore of the membrane 204) are without the sweep gas (sweep gas-free). In one implementation, the permeate 212 exits the bore of the membrane 204 at a temperature in the range of 500°C to 600°C (e.g., about 550°C), or less than 600°C, or less than 550°C, and under a pressure in the range of 1 bar to 6 bar, or in the range of 2 bar to 4 bar, or in the range of 2 bar to 3 bar.

[0042] A carbon dioxide (CO2)-rich residue 214 exits the region 210 (reaction space) of the feed pipe 202 around and outside the tubular membrane 204. The CO2-rich residue 214 may generally contain less than 10 mole percent of a combination of hydrogen and carbon monoxide. The CO2-rich residue 214 may typically be at least 90 mole percent CO2 (on a dry basis), which generally prepares the residue 114 for further compression, in certain instances for geological sequestration or enhanced oil recovery (EOR), or for further refining so that the CO2 can be used as a feedstock for another process. Vapors in the residue 214 may be condensed and removed.

[0043] In embodiments, a sweep gas (e.g., steam or nitrogen) is supplied to the bore of the tubular membrane 204 to flow through the bore and displace the permeate (hydrogen) from the bore. This hydrogen movement can maintain or displace the driving force for hydrogen permeation through the tubular membrane 204 wall from an area 210 (reaction space) external to the tubular membrane 204 to the bore. In some embodiments, the sweep gas may be provided to flow countercurrently to the input direction of the hydrocarbon 206 and steam 208 feeds. The permeate 212 can be discharged at an end (hydrocarbon feed end) opposite the end from which the retentate 214 is discharged.

[0044] If a sweep gas is used, the hydrogen purity of the permeate 212 may optionally be reported on a sweep gas-free basis. If steam is utilized as the sweep gas, the hydrogen purity of the permeate 212 may be reported on a dry basis. In implementations, steam (water) may be easily removed from the permeate 212 downstream. The permeate 212 may be subjected to dehydration (not shown).

[0045] When N2 is utilized as a sweep gas, the hydrogen purity of permeate 212 may be reported on an N2-free basis in some embodiments. In certain instances, N2 may be used as a sweep gas for permeate 212 (hydrogen and nitrogen) that is further sent, for example, for ammonia synthesis. In contrast, for mobile applications of membrane reactor 200, N2 as a sweep gas may generally be avoided in certain cases.

[0046] As described above, a catalyst 209 for steam reforming of hydrocarbons 206 is disposed within the feed tube 202. The catalyst 209 may generally be disposed in a region 210 (e.g., an annulus) between the tubular membrane 204 and the wall of the feed tube 202. The catalyst 209 may be disposed at or on the interior (inner) surface 216 of the wall of the feed tube 202, as shown. The catalyst 209 may be a coating (e.g., a wash coating) or in a structured form (e.g., a metal foam). In certain embodiments, the catalyst 209 is not in contact with the tubular membrane 204. In other embodiments, the catalyst 209 may be a catalyst packed within the region 210 and may be in contact with the membrane 204.

[0047] In embodiments of catalyst 209 disposed on or in the wall of feed pipe 202, the wall may be heated to directly heat (via contact) the catalyst 209 to promote and advance the reforming reaction. In some implementations, if catalyst 209 is used, it may be disposed on an internal resistance heater. Thus, in these implementations, the internal resistance heater (e.g., a cartridge heater) may directly heat (via contact) the reforming catalyst to promote and advance the reforming reaction.

[0048] Heat for the reforming reaction can be provided by electrical heating. The power source for the electrical heater can be a battery. The power source can also be a renewable energy source, such as photovoltaic power (e.g., solar panels) or wind power. The electrical heater can be an external electrical heater that heats the walls of the supply tube 202, or the walls of the supply tube 202 can be an electrical heater. The heated walls can be directly heated via contact with a catalyst 209 coated or disposed on the inner surface of the walls of the supply tube 202. The electrical heater can also be an internal heater disposed within the supply tube 202, for example, in region 210. Electrical heating can enable the operating temperature of the reactor 200 to be 800°C or higher, or at least 550°C, or at least 600°C. During operation, the operating temperature of the reactor 200 can range from 450°C to 650°C, or less than 700°C, less than 600°C, or less than 550°C.

[0049] Electrical heating can be implemented by heating the walls of the supply tube 202 with electrical resistance heating. For example, the walls of the supply tube 202 themselves can be electrical resistance heaters. In other words, alternating current can be passed through the walls of the supply tube 202 from a power source to generate resistive heating by the walls of the supply tube 202. In these implementations, the supply tube 202 can be made of a material acceptable for a heating element that provides sufficient electrical resistance. For example, the supply tube 202 can be a metal alloy such as a nickel-chromium alloy. Heat can be provided for the reforming reaction by an external electric heater. For example, an electric heater (not shown), such as an electric band heater or strip heater, can be disposed on the outer surface of the supply tube 202 or on a metal plate (heat distribution plate) that contacts the outer surface of the supply tube 202.

[0050] Heat for the reforming reaction in the supply tube 202 can be provided by an electric resistance heater (not shown) located in an annulus (region 210) within the supply tube 202. The resistance heater located within the supply tube 202 may be classified as an internal heater. In some embodiments, the internal resistance heater is an electric cartridge heater. A cartridge heater is a heating element typically having a cylindrical shape. A cartridge heater (heating element) or other electric resistance heater may include an outer metal enclosure (e.g., stainless steel) sheath. The internal resistance heater (heating element) may include an insulator and a metallic wire coil (as the heater). The heater wire coil may be a metal alloy, such as an alloy of nickel and chromium, or other metal alloys. During operation, an alternating current can be passed through the resistive wire coil within the internal resistance heater to generate resistive heating by the wire coil. This thermal energy is transferred from the wire into the metal sheath via conduction and then to the surrounding area and volume.

[0051] Additionally, in certain implementations, the hydrocarbons 206 (and vapor 208) in the pathway to the membrane reactor 200 may be heated via an electric heater or via a heat transfer medium in a heat exchanger. As noted, exemplary operating temperatures of the reactor 200 at which the reforming reaction may occur may be less than 600° C., or less than 550° C. The operating pressure within the reaction space 210 in the vessel 102 may be, for example, in the range of 20 bar to 50 bar, or in the range of 30 bar to 40 bar, or at least 15 bar, at least 25 bar, or at least 35 bar.

[0052] In certain embodiments, the inlet section of the membrane reactor 200 is packed with a hydrocarbon pre-reforming catalyst (e.g., nickel-based, nickel-ruthenium, etc.) inside the feed tube 202. The pre-reforming catalyst can facilitate the conversion of higher hydrocarbon molecules in the hydrocarbon 106 feed to C1 (methane)-type compounds, and this methane-rich syngas then flows forward through the feed tube 202 over the catalyst 209 of the membrane reformer 200. Thus, in these embodiments, the membrane reactor 200 may be an integrated pre-reformer and reformer. The portion of the membrane reactor 200 having the feed tube 202 with the pre-reforming catalyst can be characterized as a pre-reforming reactor. The downstream portion of the membrane reactor 200 including the feed tube 202 with the catalyst 209 can be characterized as a reforming reactor. This configuration having a pre-reforming reactor section integrated with a reforming reactor section may be applicable to the membrane reactor or multiple membrane reactors of the reformer shown in subsequent figures.

[0053] Finally, in certain embodiments, a dry reforming catalyst (e.g., noble metal-based or Ni-molybdenum (Ni-Mo) on magnesium oxide [MgO]) is packed toward (near, adjacent to, or at) the outlet of the membrane reactor 200. In implementations, because most of the produced hydrogen has permeated, the reactor mixture toward the outlet may have a high concentration of carbon species (e.g., CO, CO, CH). The mixture may also have unconverted steam (water). This carbon-species-rich environment near or at the outlet can be processed through the dry reforming catalyst. The dry reforming catalyst can facilitate the conversion of remaining CH or hydrocarbons by reacting CH (and other hydrocarbons) with CO to CO and H. The dry reforming catalyst can help reduce the tendency for coke to form on the membrane 204 surface and promote the conversion of remaining hydrocarbons to H. This configuration with dry reforming catalyst near, adjacent to, and / or at the outlet may be applicable to the membrane reactor or multiple membrane reactors of the reformer shown in subsequent figures.

[0054] 3 is a cross-sectional end view of a catalytic membrane reactor 300 (reformer), which may be similar to the membrane reactors 100 and 200 of the previous figures. In the illustrated embodiment, the reactor 300 has a tube-in-tube configuration. In particular, the reactor 300 includes a feed tube 302 (feed conduit) and a hydrogen-selective tubular membrane 304 (membrane tube) disposed within the feed tube 302. The bore 306 of the tubular membrane 304 may be classified as a lumen.

[0055] The vertical distance of the gap (annulus volume) between the feed tube 302 and the tubular membrane 304 can be specified to allow the reforming reaction and hydrogen permeation through the tubular membrane 204 to proceed. This gap is generally the region 308 that contains the reaction space for the reforming reaction, on the retentate side of the tubular membrane 304.

[0056] The supply pipe 302 may be a pipe that is a cylindrical or tubular conduit and may be classified as an outer pipe or external conduit. The supply pipe 302 may be a pressure vessel rated according to applicable industry standards. The supply pipe 302, as a conduit or vessel, may accommodate the stated operating pressures and temperatures. In implementation, the supply pipe 302 may be considered the reactor 300 vessel that contains the contents of the reactor 300. In some examples, the supply pipe 302 is stainless steel.

[0057] The reactor 300 includes a catalyst 310 disposed in a region 308, which is a reaction space. The catalyst 310 is a reforming catalyst and may include a WGS catalyst. The catalyst 310 may be disposed on or within the inner surface of the feed pipe 302. For example, the inner surface of the feed pipe 302 may be coated with the catalyst 310. In implementations, the catalyst 310 may be a structured catalyst, such as a foam, mesh, monolith, or microlith catalyst. In implementations of the catalyst 310 as a structured catalyst, the catalyst 310 may be a foam catalyst, mesh catalyst, monolith catalyst, microlith catalyst, or the like. The catalyst 310 may also be a packed catalyst within the region 308.

[0058] The feed tube 302 can be heated by electrical resistance heating, which during operation can heat the walls of the feed tube 302 and thus the catalyst 310 and other contents (e.g., reactants) within the feed tube 302. The electrical heating of the feed tube 302 can provide the desired operating temperature of the reactor 300.

[0059] In certain embodiments, the supply tube 302 is heated directly by an external electric heater in contact with the outer surface 312 of the supply tube 302. The supply tube 204 may also be heated with an external electric heater by conduction through metal plate(s) (heat distribution plates) in contact with the outer surface 308 of the supply tube 302. As described with respect to FIG. 2, other electric heater configurations are also applicable. For example, the wall of the supply tube 302 may be the heating element of an electric resistance heater. In these embodiments, the metallurgy of the supply tube 302 may be a metal other than stainless steel (e.g., a nickel-chromium alloy).

[0060] The tubular membrane 304 disposed within the feed pipe 302 may be a tubular support (e.g., porous ceramic) with a hydrogen-selective membrane material disposed thereon. Thus, the wall of the tubular membrane 304 may be the tubular support plus the membrane material. The membrane material of the tubular membrane 304 may be, for example, palladium or a palladium alloy. The palladium alloy may be, for example, a palladium-platinum (Pd-Pt) alloy, a palladium-gold (Pd-Au) alloy, a palladium-ruthenium (Pd-Ru) alloy, or a ternary alloy of these elements with palladium and Pt, Au, or Ru. In some examples, the membrane material has a thickness of at least 2 microns (micrometers) or at least 3 microns, ranging from 2 to 20 microns, 3 to 10 microns, and 3 to 6 microns. The thickness of the membrane material may be less than 30 microns, less than 20 microns, or less than 10 microns. As shown, the membrane material can be disposed (e.g., deposited) on a tubular substrate, such as a dense or porous tubular support that is ceramic or metal with a ceramic interlayer, in which case the wall of the tubular membrane 304 can comprise the membrane material and the support.

[0061] An insert tube 314 (inner tube) is disposed within the bore 306 of the tubular membrane 304. The insert tube 314 (e.g., a stainless steel tube) has an interior volume 316 for routing of a sweep gas. The routing can facilitate the sweep gas moving the hydrogen permeate within the bore 306 in a direction counter to the flow in the outer region 308 (retentate side) of the tubular membrane 304. See, for example, the following description of routing of a sweep gas through an insert tube as shown in FIGS. 4 and 7.

[0062] The outer diameter of the supply pipe 302 may be, for example, in the range of 15 millimeters (mm) to 50 mm. The wall thickness of the supply pipe 302 may be, for example, in the range of 1 mm to 3 mm. The outer diameter of the tubular membrane 304 may be, for example, in the range of 8 mm to 30 mm. The wall thickness of the tubular membrane 304 may be, for example, in the range of 1 mm to 3.5 mm. The outer diameter of the insertion pipe 314 may be, for example, in the range of 4 mm to 15 mm. The wall thickness of the insertion pipe 314 may be, for example, in the range of 0.3 mm to 1.5 mm. These numerical values ​​for the dimensions of the components of the reactor 300 are exemplary and are not meant to limit the present technology.

[0063] In one example of outer diameter x wall thickness dimensions, supply tube 302 is 26.9 mm x 1.6 mm, tubular membrane 304 is 14.0 mm x 2.0 mm, and insertion tube 314 is 7.0 mm x 0.5 mm. Thus, in this example, the thickness (vertical distance) of the annular volume (region 308) between the inner surface of the wall of supply tube 302 and the outer surface of tubular membrane 304 is 11.3 mm. The thickness (vertical distance) of the annular volume within bore 306 between the inner surface of the wall of tubular membrane 304 and the outer surface of insertion tube 314 is 5.0 mm.

[0064] Finally, the membrane reactor 300 may be a unit within a module of multiple membrane reactors 300. The module may be present in an entire membrane reforming reactor having multiple modules of multiple membrane reactors 300, as described below. Multiple modules may be operatively coupled. Insert pipes 314 can facilitate fluid coupling of membrane reactors 300 within (and between) the modules for a sweep gas counter-flow arrangement throughout the membrane reformer.

[0065] FIG. 4 illustrates a membrane reactor 400 that may be within a module within a membrane reformer having multiple modules of membrane reactors 400. In the illustrated example, the top 402 of the membrane reactor 400 may be coupled to other membrane reactors 400 within the module. A module typically has two or more membrane reactors 400. The module may include piping and associated connectors for coupling the membrane reactors 400 within the module. A membrane reformer may have multiple operatively connected modules. The illustrated membrane reactor 400 may be characterized as a unit (reactor unit) within a module having multiple such units. Additionally, the overall membrane reformer may have multiple modules. The membrane reactor 400 (and the membrane reformer as a whole) may have the operating conditions described above with respect to the previous figures.

[0066] The membrane reactor 400 includes a feed tube 302, which may be the outer tube of the reactor 400. The feed tube 302 may be stainless steel or other alloys, such as an iron-chromium-aluminum alloy. During operation, the feed tube 302 may act as a heater tube, in that electrical heating may be applied to the outer surface of the feed tube 302. In some implementations, an electrical heating plate (heat distribution plate) is used to heat the feed tube 302 by conduction from an electrical heating plate in contact with the outer surface of the feed tube 302. In certain implementations, the wall of the feed tube 302 itself may be an electrical resistance heating element that receives electricity for electrical resistance heating. In that case, the feed tube 302 may be made of a material (e.g., a nickel-chromium alloy) that provides sufficient resistance to electricity for electrical heating.

[0067] The reactor 400 includes two hydrogen-selective tubular membranes 304A and 304B, each having a respective bore 306. The combination of the two tubular membranes 304A and 304B can be considered a single tubular membrane with each of the two tubular membranes 304A, 304B being a longitudinal portion of a single tubular membrane.

[0068] The two tubular membranes 304A, 304B are coupled together via a connector block 404. The reactor 400 includes an insert tube 314 (as described above for the sweep gas) disposed within the bore 306. When the insert tube 314 is disposed, it is continuous through the inner diameter of the connector block 404.

[0069] The two tubular membranes 304A and 304B may be connected to provide a length of tubular membrane within the reactor 400. In one embodiment, the connector block 404 is a metal connector (e.g., a metal cap) with two graphite seals, one for each of the two membranes. Additionally, the reactor 400 includes a closed connector 406 (end block) at the bottom of the lower tubular membrane 304. The closed connector 406 may be an end cap (metal cap) with a seal, for example, a graphite sealant.

[0070] Two or more hydrogen-selective tubular membranes can be connected to obtain a desired membrane length in reactor 400. In other examples, a single hydrogen-selective tubular membrane without a connector block 404 can be used to provide the desired membrane length in reactor 400.

[0071] As stated, each of the tubular membranes 304A, 304B can include a hydrogen-selective membrane material (e.g., Pd or a Pd alloy) applied onto the exterior surface of the respective porous ceramic tube. The non-porous membrane material layer (e.g., a palladium or palladium alloy membrane layer) is generally a selective layer that allows primarily only hydrogen to pass through the tubular membrane and into each of the bores 306 of the tubular membranes 304A, 304B. As noted above, this membrane material layer can have a thickness ranging from, for example, 3 microns to 20 microns.

[0072] The membrane reactor 400 includes a region 308 outside the tubular membranes 304A and 304B as a reaction space for the reforming reaction (and the WGS reaction). A catalyst 310 is disposed in the region 308, such as on the inner surface of the wall of the supply pipe 302. In one particular example, the catalyst 310 is applied to the inner surface of the wall of the supply pipe 302 via washcoating. In this case, the supply pipe 302 may be made of a material (e.g., an iron-chromium-aluminum alloy) that is conducive to receiving the washcoat layer of the catalyst 310. In an embodiment in which a washcoat catalyst is used as the catalyst 310, the washcoat catalyst 310 may have a thickness (layer thickness) ranging from 100 microns (μm) to 400 μm, for example. The thickness may be at least 50 μm or at least 250 μm. The thickness may be less than 500 μm or less than 250 μm. The catalyst 210 disposed on the inner surface of the supply pipe 302 may be a washcoat of a low-temperature reforming catalyst (e.g., for steam reforming). The catalyst 210 may further include a WGS catalyst.

[0073] During operation, a feed 408 is introduced into region 308 for the reforming reaction (and WGS reaction) to produce hydrogen and carbon dioxide in region 308 outside of the tubular membranes 304A, 304B. As noted above, heat for the endothermic reforming reaction can be provided by electrical heating. The feed 408 can include hydrocarbons and steam. The hydrocarbons can include, for example, natural gas, methane, LPG, a mixture of C1-C5 hydrocarbons, etc. The feed 408 can be residue from another membrane reactor 400, depending on the arrangement of the membrane reactors 400 within a given module of the overall membrane reformer.

[0074] As shown, the product gas produced in region 310 includes hydrogen and carbon dioxide. The hydrogen diffuses through the tubular membranes 304A, 304B into the bores 316 of the connected tubular membranes 304A, 304B. The carbon dioxide exits region 308 as residue 410. This technique generally involves converting hydrocarbons to hydrogen while simultaneously diffusing the hydrogen through the tubular membranes.

[0075] A sweep gas 412 (e.g., steam or nitrogen) is supplied to the insert 314. The sweep gas 412 flows downward through the insert 314 (see volume 316 in FIG. 3 ) and exits the lower end of the insert 314. The sweep gas 412 then flows upward through the bore 306 (outside the insert 314), transporting hydrogen in a countercurrent direction relative to the flow of the feed 408 reactants through the region 308. The insert 314 thus routes the sweep gas 412 to promote the flow of the sweep gas 412 (and the transported hydrogen) in the bore 316 adjacent the membrane wall in a countercurrent direction relative to the feed 408 and retentate 410. This countercurrent flow in transporting hydrogen from the bore 306 can promote diffusion of hydrogen from the region 310 through the tubular membranes 304A, 304B and into the bore 306. The displaced hydrogen product may exit the bore 306 as permeate 414. The permeate 414 may include the sweep gas 412 that displaces the hydrogen.

[0076] In the illustrated embodiment, the feed tube 302 and membrane 304B terminate at the bottom of the reactor 400. The retentate 410 can be discharged from region 308 of the feed tube 102. The retentate 410 piping can be coupled to another membrane reactor 400 in the module. The insert tube 314 and permeate 414 piping may be operatively coupled to another membrane reactor 400 in the module. FIG. 4 shows the flow configurations of the feed 408 and sweep gas 412, as well as the retentate 410 and permeate 414, from the membrane reactor 400 reformer module. The overall counter-current flow between the permeate 414 and the feed 408 is achieved by the placement of the sweep gas flow utilizing the insert tube 314.

[0077] Figure 5 is the bottom 500 of the membrane reactor 400 of Figure 4. The wall of the feed pipe 302 is shown in cross section. The tubular membrane 304B is depicted showing all of the tubular membrane 304B and the bore 306.

[0078] FIG. 6 is a diagram 600 showing a longitudinally connected first tubular membrane 602, a second tubular membrane 604, and a tubular membrane 606 that is a combination of the first tubular membrane 602 and the second tubular membrane 604. The first tubular membrane 602 may be similar to tubular membrane 304A of FIG. 4. The second tubular membrane 604 may be similar to tubular membrane 304B of FIG. 4. The first tubular membrane 602 and the second tubular membrane 604 are hydrogen-selective. Thus, the tubular membrane 606 is hydrogen-selective. The tubular membrane 606 may be deployed in a membrane reforming reactor and associated modules as described.

[0079] In the illustrated example, the first tubular membrane 602 has a left flange connector 608 (e.g., with a graphite seal) and a right intermediate connector 610. The flange connector 608 has a graphite seal and may be used to connect to conduits (tubing, pipes, etc.) within a module having multiple membrane reactors of a membrane reformer. The flange connector 608 may be a tubing compression fitting rather than a flange. The second tubular membrane 604 has a left intermediate connector 612 and a right closure connector 614 (e.g., an end cap with a graphite seal). The right closure connector 614 may be similar to the end connector 406 described above with respect to FIG. 4. The tubular membrane 606 includes an intermediate connector 616 that is a mating combination of the right intermediate connector 610 and the left intermediate connector 612. The intermediate connector 616 may be similar to the connector block 404 of FIG. 4. The right closure connector 614 may instead be a connector component that mates with a connector component of a third tubular membrane (not shown) within the connector block.

[0080] Thus, Figure 6 shows the connection of membrane tubes with end caps and connecting blocks. Two or more membranes can be connected together to achieve the total length desired for the membrane module length. The connecting blocks and end caps can use different types of sealing materials. One example is a metal cap with a graphite seal.

[0081] FIG. 7 illustrates a membrane reformer module 700. A membrane reformer can have multiple similar modules. In the illustrated embodiment, module 700 (membrane module) has four membrane reactors 702, 704, 706, and 708 as units of the module 700. Therefore, the membrane reactors 702, 704, 706, and 708 (e.g., as individual membrane reactor units or module units) can be classified as a module unit. Both the feed gas and the sweep gas are in series across the reactors 702, 704, 706, and 708. As described below, module 700 includes eight tubular membranes. In one example, the total effective surface area of ​​the tubular membranes is 0.2885 square meters (m 2 )

[0082] Each of the four membrane reactors 702, 704, 706, and 708 can be similar to the membrane reactors 300 or 400 described above. For example, reactors 702, 704, 706, and 708 contain catalysts for steam reforming and WGS reactions. In the illustrated example, each membrane reactor 702, 704, 706, and 708 has two tubular membranes (hydrogen-selective) longitudinally coupled via a respective connector block 404 (e.g., intermediate connector 616 in FIG. 6 ). Thus, module 700 has eight tubular membranes. The membrane surface area of ​​module 700 (with eight tubular membranes) is, for example, 0.2 m 2 ~1.5m 2 In one example, eight tubular membranes may be used for the module 700, with a thickness of 0.2885 m. 2 As will be described below, membrane module 700 includes interconnections between reactors 702, 704, 706, and 708. Also, as will be described below, the flow configuration provides a countercurrent flow for the hydrogen sweep gas transfer relative to the feed stream.

[0083] During operation, the feed 408 is introduced into the region 308 of the first membrane reactor 702 within the feed tube 302, outside the two tubular membranes 304A, 304B. As described above, the region 308 is located between the wall of the feed tube 302 and the two tubular membranes 304A, 304B. The feed 408 may include hydrocarbons and steam. The hydrocarbons may include, for example, natural gas, methane, LPG, a mixture of C1-C5 hydrocarbons, etc. The feed 408 may be residue from another membrane reactor 400, depending on the sequencing of the modules 700 within the overall membrane reformer. A catalyst (not shown) located in the region 308 facilitates the reaction. As described above, heat for the endothermic reforming reaction may be provided by electrical heating.

[0084] Steam reforming reactions (and WGS reactions) occur in region 308 to produce hydrogen and carbon dioxide. Hydrocarbons (e.g., CH4 and heavier hydrocarbons) in the feed 408 are converted to hydrogen and carbon dioxide via steam reforming (and WGS reactions). The produced hydrogen diffuses from region 308 through the tubular membranes 304A, 304B into the bores 306 of the tubular membranes 304A, 304B. The product gas remaining in region 308 in the first reactor 702 comprises primarily carbon dioxide and may be classified as residue. Unreacted feed 408, including unreacted hydrocarbons and unreacted steam, may also be present in region 308.

[0085] The unreacted feed and carbon dioxide may flow 710 through interconnects 712 between the reactors to the region 308 of the subsequent reactors 704, 706, 708. The unreacted feed may be converted to hydrogen and carbon dioxide. In the subsequent reactors 704, 706, 708, the produced hydrogen may diffuse from the region 308 through the tubular membrane to the bore 306 within the respective reactor. Stream 710 may exit the feed pipe 302 of the fourth reactor 708 as retentate 714. The retentate 714 may, in some examples, be primarily carbon dioxide. The vapor in the retentate 714 may be condensed and removed from the carbon dioxide as liquid water. Each interconnect 712 for stream 710 through module 700 may include conduits and / or conduit fittings (e.g., tubing or pipe fittings), such as 180-degree bends or elbows. The conduit fittings may include compression fittings or flanged connectors to facilitate coupling between the interconnect 712 and the supply tube 302 .

[0086] The conduits of interconnect 712 may contain catalysts (e.g., packed catalysts) including reforming catalysts and WGS catalysts to further promote the reactions that convert the hydrocarbons in stream 710 into hydrogen and carbon dioxide. The catalysts packed in the conduits of interconnect 712 may be in structured form or may be coated on the interior surface of the conduits or conduit elbows, or packed bed catalysts may also use this space to create further mixing of the reactants.

[0087] In the illustrated embodiment, a sweep gas 412 is introduced into the insert tube 314 of the fourth reactor 708 to displace hydrogen from the tubular membrane bores 306 in the reactors 702, 704, 706, 708. The sweep gas 412 exits the bottom of the insert tube 314 of the fourth reactor 708. The sweep gas 412 then flows upwardly through the tubular membrane bores 306 of the fourth reactor 708 in a countercurrent direction to the flow 710. The sweep gas 412 displaces hydrogen from the bores 306.

[0088] The sweep gas 412 (including the displaced hydrogen) flows (716) from the fourth reactor 708 to the upstream reactors 702, 704, 706 via an insert tube interconnect 718 (e.g., an interconnecting conduit and / or conduit fitting, etc.) and a membrane tube interconnect 720 (e.g., an interconnecting conduit or conduit fitting, etc.). This stream 716 exits the fourth reactor 708 via the membrane interconnect 720 to the third reactor 706. In the third reactor 706, stream 716 (sweep gas and displaced hydrogen) flows downward through the bore 306, displacing hydrogen in a countercurrent direction to the feed / retentate stream 710. Stream 716 then enters the bottom of the insert tube 314 in the third reactor 706 and flows through the insert tube interconnect 718 to the second reactor 704. In the second reactor 704, stream 716 exits the bottom of insert tube 314 and flows upward through bore 306, carrying hydrogen in a countercurrent direction to the feed / retentate stream 710. This stream 716 of sweep gas and product hydrogen exits the second reactor 704 through membrane tube interconnect 720 to the first reactor 702. In the first reactor 702, stream 716 flows downward through bore 306, carrying hydrogen in a countercurrent direction to the flow of feed 408. Stream 716 (product hydrogen and sweep gas) enters the bottom of insert tube 314 and exits the first reactor 702.

[0089] The exhaust may be classified as permeate 722 (primarily hydrogen) with a sweep gas. The permeate 722 with the sweep gas may be sent as a sweep gas to another module 700 within the membrane reformer. Alternatively, the permeate 722 with the sweep gas may be treated to remove the sweep gas from the permeate 722, and the hydrogen may be collected or distributed as product hydrogen. In implementations using steam as a sweep gas, the steam may be condensed (e.g., in a heat exchanger or heat exchanger vessel) to remove the steam from the hydrogen as liquid water.

[0090] The insert tube interconnect 718 and the membrane tube interconnect 720 can include conduit fittings (e.g., tubing or pipe fittings), such as 180-degree bends or elbows, compression fittings, flanged connectors, etc. In one example, the membrane tube interconnect 720 can be coupled to the tubular membrane via a flange connector, such as the flange connector 612 described with respect to FIG.

[0091] The module 700 may have a pre-reforming catalyst at an inlet portion of the module 700. One or more of the reactors 702, 704, 706, 708 may have a pre-reforming catalyst at an inlet portion inside the feed conduit 302. In one embodiment, the first reactor 702 that receives the feed 408 has a pre-reforming catalyst at an inlet portion of the feed conduit 302. The pre-reforming catalyst may facilitate the conversion of higher hydrocarbons in the feed 408 to methane.

[0092] The module 700 may have a dry reforming catalyst at an outlet portion of the module 700. One or more of the reactors 702, 704, 706, 708 may have a dry reforming catalyst at an outlet portion inside the feed line 302. In one embodiment, the last reactor 708, which discharges the residue 714, has a dry reforming catalyst at the outlet portion of the feed line 302. The dry reforming catalyst promotes conversion of hydrocarbons to H and may provide resistance to coking.

[0093] 8 illustrates a membrane reformer 800 having a first module 802 of five membrane reactors and a second module 804 of five membrane reactors. Thus, the membrane reformer 800 (or this portion of the membrane reformer 800) has ten membrane reactors, which may also be classified as membrane units. In this illustrated implementation, ten membrane reactors operate in series. Each of the ten membrane reactors may be similar to the membrane reactors described with respect to previous figures.

[0094] In this example, the tubular membranes in each membrane reactor are two tubular membranes (hydrogen-selective) joined longitudinally via a connector block. Thus, membrane reformer 800 has 20 tubular membranes. In one implementation, the cumulative total effective surface area of ​​the 20 tubular membranes is 0.7213 m. 2 The cumulative membrane surface area of ​​the membrane reformer 800 can generally increase as membrane reactors and tubular membranes are added to the membrane reformer 800.

[0095] The five membrane reactors in each module 802, 804 are mounted behind (and in contact with) a respective heat distribution plate 806. The heat distribution plate 806 is a metal plate that conducts heat generated by the strip heaters 808 to the membrane reactors. The strip heaters 808 are mounted on the heat distribution plate 806. In one example, the sheath temperature of the strip heaters 808 during operation is at least 760°C. The strip heaters may include a heating element (electrically resistive metal), a protective sleeve or sheath, and mounting hardware. The metallurgy of the strip heaters may typically be steel. The strip heaters may include electrical terminals (e.g., with leads) extending from the sheath for power connection. The power source (not shown) may be a battery, renewable energy, or the like. The strip heaters can generally be bolted or clamped to a solid surface. Some strip heaters include mounting holes for attaching the strip heater to a surface.

[0096] The membrane reformer 800 includes a temperature controller 810 for the strip heater 806. The temperature controller 810 (e.g., a mechanical thermostat or a bimetallic thermostat) may be associated with a control system that dictates the operating temperature of the membrane reformer 800. In this example, the temperature controller 810 is located on the heat distribution plate 806. The membrane reformer 800 may have external insulation for thermal efficiency and personnel protection.

[0097] The membrane reformer 800 has a feed inlet 812 for hydrocarbons and steam and a retentate outlet 814 for exhausting carbon dioxide. The membrane reformer 800 also has a permeate hydrogen outlet (not shown), which may be located at the top of the membrane reformer 800. The exhausted permeate hydrogen may comprise a sweep gas. An interconnecting conduit 816 (e.g., tubing, pipes, fittings, elbows, etc.) operably couples the two modules 802 and 804 and their membrane reactors with respect to permeate and retentate. An interconnecting conduit 818 at the top of the membrane reformer 800 is for the sweep gas.

[0098] The interconnecting conduit 816 at the bottom of the membrane reformer 800 may contain a 180-degree (U-shaped) elbow or bend containing additional catalyst (e.g., steam reforming catalyst and WGS catalyst) for converting hydrocarbons to hydrogen and carbon dioxide. The catalyst may be coated on the inside surface of the elbow, or in a structured form, or as a packed bed catalyst. This catalyst is in addition to the catalyst located in the region outside the tubular membrane within the membrane reactor.

[0099] In summary, Figure 8 shows the details of a module design with the connection of 10 membrane units with a total of 20 membranes connected to provide a larger membrane surface area. The permeate and retentate interconnections are also shown. A heat distribution device is also shown. A heat distribution plate is utilized in conjunction with strip heaters to provide energy for the reforming reaction. Additionally, the heat distribution plate can provide physical (mechanical) support for the module, while a support structure (not shown) can provide mounting for the module conduits (piping). The support can be, for example, at the top of the module. In certain implementations, the conduits can be maintained in a generally suspended position to facilitate thermal expansion of the conduits while avoiding significant mechanical stress within the conduits.

[0100] FIG. 9 illustrates a membrane reformer 900 having eight modules 902, which may be similar to modules 802, 804 in FIG. 8. In fact, each of the eight modules 902 has five membrane reactors (membrane units). The five membrane reactors in each module 902 operate in series. In an example, multiple modules 902 can be coupled in series (and / or parallel) to increase the throughput (hydrogen production) of the membrane reformer 900. In this example, eight modules 902 operate in series. The membrane reformer 900 includes interconnections 904 between the modules 902 as shown. A feed inlet 906 can receive hydrocarbons and steam. A retentate outlet 908 can output primarily carbon dioxide. The membrane 900 also includes a permeate hydrogen output. See, for example, permeate hydrogen (and sweep gas) output 1018 in FIG. 10.

[0101] Figures 10, 11, 12, and 13 show the details of the flow distribution within the manifold from above and below. The "U" shaped interconnect as shown in Figure 9 can also be used to pack additional catalyst between the two modules as required by the reaction or design of the membrane reformer. The catalyst packed in this region can be in structured form, coated in tubular form, or purely packed bed catalyst, and this space can also be used to allow further mixing of the reactants to occur.

[0102] 10 shows the top 1000 (including manifold) of a membrane reformer module (e.g., top module 902 in FIG. 9). The membrane reactor (module unit) is placed behind and in contact with the heat distribution plate 1002.

[0103] The feed 1004 (hydrocarbon and steam) flows serially through the membrane reactors in the direction generally indicated by arrow 1006. The feed 1004 flows through the region outside the tubular membranes (retentate side) within the membrane reactor. The effluent 1008 from this region of the last membrane reactor in the series may be used as retentate (primarily carbon dioxide) or for feed to the next module in the membrane reformer.

[0104] A sweep gas 1010 is introduced into the bore of the tubular membrane in the last membrane reactor in the series. As explained, an insert tube can be used. The sweep gas 1010 flows generally in the direction indicated by arrow 1012. The sweep gas 1010 flows between the membrane reactors (modular units) via an interconnecting conduit 1014. The interconnecting conduit 1014 may be a U-elbow with a conduit fitting 1016 (e.g., a plumbing fitting) that connects the interconnecting conduit 1014 to the tubular membrane in each membrane reactor in the series. As explained above, the sweep gas 1010 displaces hydrogen from the bore of the tubular membrane. Permeate 1018 exits the membrane bore of the first membrane reactor.

[0105] 11 is an upper portion 1100 of a multiple membrane reactor membrane reformer module. In this view, the upper portions of three of the multiple membrane reactors are shown coupled to a manifold 1102. The flow configurations highlighted by reference numerals include a sweep gas at 1104, a sweep gas flow path 1106, a downward sweep gas flow 1108, an upward return sweep gas 1110, an upward feed flow 1112, a feed flow path 1114, and a downward feed flow 1116.

[0106] Each of the three membrane reactors includes a feed tube 1118 (feed conduit or outer conduit), a tubular membrane 1120, a bore 1122 in the tubular membrane 1120, and a region 1124 within the feed tube 1118 outside the tubular membrane 1120 where the catalyst is located and the reforming / WGS reaction occurs. Each of the three membrane reactors includes an insert tube 1126 that is located within the bore 1122 and enters the manifold 1102.

[0107] In this example, a flanged connector 1128 couples the tubular membrane to the sweep gas interconnect. The flange connector 1128 may be similar to flange connector 608, left, in FIG. 6. The flange connector 1128 includes a flange portion, an outer portion 1130, and a graphite material 1132. The flange portion and outer portion 1130 apply compression to the graphite material 1132, providing a graphite seal through the graphite material 1132.

[0108] FIG. 12 is a feed interface 1200 on the bottom of a membrane reformer module. The feed interface 1200 may be for a feed stream from or to a conduit 1202. Shown are: (1) a feed conduit 1204, (2) a tubular membrane 1206 disposed within the feed conduit, and (3) an area volume 1208 between the wall of the feed conduit 1204 and the tubular membrane 1206. The feed interface 1200 includes an end cap 1210 having an end cap portion that compresses graphite 1212 to provide a graphite compression seal. The end cap 1210 includes an outer portion 1214. The end cap 1210 may be similar to the closure connector right 614 of FIG. 6.

[0109] FIG. 13 illustrates an interconnection interface 1300 for the membrane reforming module for feed / retentate flows between membrane reactors (modular units). The interconnection interface 1300 includes two end caps 1302, 1304 configured similarly to the end cap 1210 in FIG. 12. The interconnection interface 1300 includes an interconnecting conduit 1306, which is a 180-degree bend. In certain embodiments, the interconnecting conduit 1306 can be used to pack additional catalyst between two membrane reactors or between two modules of a membrane reactor. This can depend on the design and operating conditions of the membrane reformer. This additional catalyst (if used) can be a catalyst packed into the interconnecting conduit 1306 in a structured form, coated on the inner surface of the interconnecting conduit 1306, or as a packed bed catalyst, which also allows for the use of this region's space to generate additional mixing of the reactants.

[0110] 14 shows a membrane reformer 1400 having four modules 1402, each having multiple membrane reactors (modular units). The modules 1402 are arranged in series with respect to the feed. The modules 1402 are arranged in parallel with respect to the sweep gas flow. By distributing the parallel sweep gas, the pressure drop on the permeate side of the membrane reformer 1400 can be reduced.

[0111] FIG. 15 illustrates a membrane reformer 1500 having eight modules 1502, each having multiple membrane reactors (modular units). The membrane reformer 1500 is configured to accept additional modules of multiple membrane reactors, including as multiple lines of modules. The membrane reformer 1500 includes a feed header 1504 and a retentate discharge header 1506. Both the feed header 1504 and the retentate discharge header 1506 have connection points 1508 (e.g., tee fittings) for accepting additional modules. The membrane reformer 1500 includes a sweep gas supply header 1510 and a permeate discharge header 1512. In this example, the membrane reformer 1500 includes at least 40 membrane reactors (modular units) and a 2.885 m 2 and 80 tubular membranes providing a total effective surface area of ​​the tubular membranes equal to 100 .mu.m.

[0112] FIG. 16 illustrates a membrane reformer 1600 with four lines 1602, each having four modules 1604 of multiple membrane reactors (modular units). In each line 1602, the modules 1604 are connected in series on the feed side and in parallel on the sweep gas side. The feed stream is distributed in parallel to each line 1602 to reduce retentate pressure drop. The sweep gas stream is distributed in parallel to each line 1602. Each module 1604 has a counterflow of sweep gas to the feed stream across the tubular membrane. FIG. 16 illustrates a membrane reformer with four lines 1602, each having four modules 1604 of multiple membrane reactors (modular units). In each line 1602, the modules 1604 are connected in series on the feed side and in parallel on the sweep gas side. The feed stream is distributed in parallel to each line 1602 to reduce retentate pressure drop. The sweep gas stream is distributed in parallel to each line 1602. Each module 1604 has a counterflow of sweep gas to the feed stream across the tubular membrane. 3 1 shows the modular combination of membrane modules in achieving greater production capacities of hydrogen up to 1000 kJ / hr. Also shown are the connections for the sweep gas stream, permeate stream, feed stream, and retentate stream.

[0113] The membrane reactors and membrane reformers described herein can have operating temperatures below 650°C, with heat provided by, for example, an electric heater. The hydrogen production capacity of the membrane reformer is 10,000 Nm 3 / hr less than 5,000 Nm of hydrogen 3 / hr or less than 1,000 Nm 3 / hr hydrogen. The hydrogen product exiting the membrane reformer may be at least 90 mole percent (mol%) hydrogen or at least 99.9 mol% hydrogen on a dry basis, without sweep gas. When the sweep gas is steam, the hydrogen product may be at least 90 mol% hydrogen or at least 99.9 mol% hydrogen on a dry basis. The residue exiting the membrane reformer may be at least 90.0 mol% carbon dioxide on a dry basis.

[0114] Figures 17A and 17B show a membrane reformer 1700 that uses a multi-module design similar to the reformer 1600 of Figure 16. The membrane reformer 1700 is within a box 1702. The box 1702 can be characterized as a housing. Figure 17A shows the reformer 1702 within the box 1702 without siding (side walls). Figure 17B shows the reformer 1700 within the box 1702 with siding. In an example, the box 1702 is an electrically heated box. The box 1702 may be a rectangular box and may have dimensions of less than 5 m width, less than 5 m length, and less than 5 m height.

[0115] In one example, 12 lines (four each module) are arranged in the box 1702. Each module has 10 membrane reactors (module units). The tubular membranes in each membrane reactor are two tubular membranes joined longitudinally. Therefore, the membrane reformer 1700 in this example includes 480 membrane reactors (module units) and 960 tubular membranes in the box 1702, which has dimensions of 3 m x 3 m x 3 m. The total effective surface area of ​​the 960 tubular membranes is 34.62 m. 2 The membrane reformer 1700 can be operated at a sweep gas pressure of, for example, 5 bar. Here, the membrane reformer 1700 is operated at a sweep gas pressure of 100 Nm 3 / hr hydrogen production capacity.

[0116] The present invention enables integrated hydrogen production by performing the steps of steam reforming, water-gas shift reaction, and hydrogen separation / purification in one single reactor. It also allows for in-situ separation of H2 and CO2 produced using a hydrocarbon feedstock. This process enhancement results in an efficient and simple hydrogen production process, which can result in reduced hydrogen production costs due to significantly reduced capital and operating costs. This enhancement also allows the process to be run at much lower operating temperatures and higher pressures than conventional reforming processes used for hydrogen production.

[0117] Conventional SMR processes are inefficient when scaled down. This technology is more efficient and can provide a smaller footprint for hydrogen production. While hydrogen produced in large-scale centralized SMR plants is inexpensive, transportation and storage are inefficient (and expensive) due to hydrogen's low density and the specialized trucks (tube trailers) and tanks (high-pressure carbon fiber reinforced vessels) required. This technology, in certain embodiments, utilizes hydrocarbons that can be efficient (and inexpensive) to transport, facilitating efficient production of hydrogen where it is needed (including mobility applications). Furthermore, the residue is primarily carbon dioxide at relatively high pressures, which may be ready for capture, for example, for sequestration, enhanced oil recovery (EOR), or reuse as a feedstock.

[0118] One embodiment is a membrane reformer having multiple membrane reactors for producing hydrogen. The hydrogen production capacity of the membrane reformer is 10,000 Nm 3 / hr or less than 1,000 Nm 3 / hr of hydrogen. The membrane reactors of the membrane reformer can be operatively arranged in parallel or series, or both. In some examples, the membrane reformer includes at least 30 membrane reactors. In one example, the at least 30 membrane reactors are arranged in a box having a width of less than 5 m, a length of less than 5 m, and a height of less than 5 m. The membrane reformer can include fewer than 30 membrane reactors. The membrane reformer can include an electric heater (e.g., an electric strip heater) for providing heat to the multiple membrane reactors to maintain an operating temperature of the membrane reformer below 650°C. The membrane reformer can include a heat distribution plate in contact with the multiple membrane reactors, the electric heater being disposed on the heat distribution plate.

[0119] Each membrane reactor includes (1) a feed conduit as the outer conduit of the membrane reactor for receiving hydrocarbons and steam into a region outside the tubular membrane within the feed conduit; (2) a catalyst (including a steam reforming catalyst) disposed in a region within the feed conduit outside the tubular membrane for converting the hydrocarbons to hydrogen and carbon dioxide; and (3) a tubular membrane within the feed conduit for diffusing hydrogen from that region through the tubular membrane to a bore of the tubular membrane. This region is the retentate side of the tubular membrane and discharges a retentate containing carbon dioxide. The bore is the permeate side of the tubular membrane and discharges a permeate containing hydrogen. Each membrane reactor has an insert tube disposed within the bore to facilitate the flow of a sweep gas through the bore in a countercurrent direction to the flow of hydrocarbons and steam in the region outside the tubular membrane. The hydrocarbons received in the feed conduit can include, for example, methane, liquid petroleum gas (LPG), or a mixture of C1-C5 hydrocarbons, or any combination thereof.

[0120] In some implementations, the outer diameter of the feed conduit may be, for example, in the range of 15 mm to 50 mm. The wall thickness of the feed conduit may be, for example, in the range of 1 mm to 3 mm. The outer diameter of the tubular membrane may be, for example, in the range of 8 mm to 30 mm. The wall thickness of the tubular membrane may be, for example, in the range of 1 mm to 3.5 mm. The outer diameter of the insertion tube may be, for example, in the range of 4 mm to 15 mm. The wall thickness of the insertion tube may be, for example, in the range of 0.3 mm to 1.5 mm. The tubular membrane in each membrane reactor may be, in some examples, two tubular membranes joined longitudinally. In certain implementations, the catalyst is not in contact with the tubular membrane. The catalyst may further include a WGS catalyst.

[0121] The plurality of membrane reactors includes at least a first membrane reactor and a second membrane reactor. In an implementation, the membrane reformer can have an interconnecting conduit connecting the feed conduit of the first membrane reactor to the feed conduit of the second membrane reactor, and the feed conduit of the second membrane reactor receives the residue from the first membrane reactor through the interconnecting conduit. The residue discharged from the first membrane reactor to the feed conduit of the second membrane reactor can include steam and hydrocarbons unreacted in the first membrane reactor.

[0122] Another embodiment is a 5,000 Nm 3A method for producing hydrogen at less than 1000 kJ / hr. The method includes supplying hydrocarbons and steam to a membrane reformer having multiple membrane reactors. The method includes converting the hydrocarbons to hydrogen and carbon dioxide via a catalyst (including a steam reforming catalyst) disposed outside tubular membranes in the multiple membrane reactors. The catalyst includes a steam reforming catalyst and may further include a WGS catalyst. In some implementations, the catalyst is not in contact with the tubular membranes. The method includes diffusing hydrogen through tubular membranes in the multiple membrane reactors into each bore of the tubular membrane. Diffusing hydrogen through the tubular membrane may be simultaneous with converting the hydrocarbons to hydrogen. The method includes flowing a sweep gas through each bore to move hydrogen in a countercurrent direction relative to the flow of hydrocarbons and steam outside the tubular membranes. In some implementations, the movement of hydrogen within each bore by the sweep gas increases the permeation of hydrogen outside the tubular membrane through the tubular membrane. The method includes discharging hydrogen as permeate from each bore using a sweep gas and discharging carbon dioxide outside the tubular membrane as residue (e.g., including unreacted vapor) from the multiple membrane reactors.

[0123] The method can include electrically heating the plurality of membrane reactors, wherein the operating temperature of the plurality of membrane reactors is less than 650°C. Electrically heating the plurality of membrane reactors can include electrically heating the plurality of membrane reactors via a heat distribution plate in contact with the plurality of membrane reactors. In an implementation, an operating pressure outside the tubular membranes in the plurality of membrane reactors is in the range of 10 bar to 50 bar. The operating pressure of each bore can be in the range of 1 bar to 5 bar.

[0124] The method can include flowing a retentate from a first membrane reactor of the plurality of membrane reactors to a second membrane reactor of the plurality of membrane reactors, the retentate from the first membrane reactor including steam and hydrocarbons unreacted in the first membrane reactor. The method can include discharging hydrogen as a permeate with a sweep gas from at least one bore of each of the bores as product hydrogen from the membrane reformer, the product hydrogen being at least 90 mole % hydrogen on a sweep gas-free basis. In the case of the sweep gas as steam, the method can include condensing the sweep gas in the product hydrogen to remove the sweep gas as liquid water from the product hydrogen.

[0125] Yet another embodiment is a method for generating hydrogen. The method includes producing hydrogen using a membrane reformer having multiple membrane reactors. Each membrane reactor has an outer tube and a tubular membrane (e.g., two tubular membranes joined longitudinally) within the outer tube. Hydrogen production in each membrane reactor includes (1) converting hydrocarbons to hydrogen and carbon dioxide in the presence of steam over a catalyst (including a reforming catalyst, which may include a WGS catalyst) in a region of the outer tube outside the tubular membrane; (2) diffusing hydrogen from that region through the tubular membrane into a bore of the tubular membrane, where the region is the retentate side of the tubular membrane and the bore is the permeate side of the tubular membrane; (3) venting carbon dioxide (e.g., along with unreacted steam) from that region; (4) flowing a sweep gas through the bore to move hydrogen from the bore in a countercurrent direction relative to the flow of hydrocarbons in the region outside the tubular membrane; and (5) venting the hydrogen and sweep gas from the bore. The method can include facilitating a countercurrent flow of a sweep gas through an insert tube disposed within the bore. The operating temperature of the membrane reactor can be less than 650°C. The operating pressure outside the tubular membrane within the outer tube can range from 10 bar to 50 bar. The operating pressure of the bore can range from 1 bar to 5 bar. As stated, dimensions can include an outer diameter of the outer tube ranging from 15 mm to 50 mm, a wall thickness of the outer tube ranging from 1 mm to 3 mm, an outer diameter of the tubular membrane ranging from 8 mm to 30 mm, and a wall thickness of the tubular membrane ranging from 1 mm to 3.5 mm.

[0126] The method can include flowing carbon dioxide discharged from a first membrane reactor region of the plurality of membrane reactors to a second membrane reactor region of the plurality of membrane reactors, the carbon dioxide from the first membrane reactor region comprising unreacted steam and unreacted hydrocarbons. The method can include discharging hydrogen from the membrane reformer as product hydrogen, the product hydrogen comprising at least 90 mol % hydrogen on a dry basis, excluding sweep gas. The sweep gas can be steam, and the product hydrogen can be at least 90 mol % hydrogen on a dry basis.

[0127] Yet another embodiment is a method for producing hydrogen. The method includes producing hydrogen using a membrane reformer having multiple membrane reactors. Each membrane reactor has an outer conduit (an outer tube, a feed conduit, a feed tube) and a tubular membrane (e.g., two longitudinally joined tubular membranes) within the outer conduit. In this embodiment, the inlet section of the membrane reformer is filled with a hydrocarbon pre-reforming catalyst (e.g., nickel-based, nickel-ruthenium, etc.). The pre-reforming catalyst can facilitate the conversion of higher hydrocarbon molecules in the feed to C1 (methane)-type compounds, and this methane-rich synthesis gas is then sent downstream of the membrane reformer.

[0128] Yet another embodiment is a method for generating hydrogen. The method includes producing hydrogen using a membrane reformer having multiple membrane reactors. Each membrane reactor has an outer tube and a tubular membrane (e.g., two tubular membranes joined longitudinally) within the outer tube. In this embodiment, a dry reforming catalyst (e.g., Ni-Mo on MgO, a noble metal-based catalyst, etc.) is packed toward (near, adjacent to, or at) the outlet of the membrane reactor. In this implementation, because most of the produced hydrogen has permeated, the reactor mixture toward the outlet can have a high concentration of carbon species (e.g., CO, CO, CH). The mixture may also have unconverted steam (water). This carbon-species-rich environment near or at the outlet can be processed through a dry reforming catalyst. The dry reforming catalyst can facilitate the conversion of remaining CH or hydrocarbons by reacting with CO to CO and H. The dry reforming catalyst may contribute to reducing the tendency for coke formation on the membrane surface as well as promoting the conversion of residual hydrocarbons to H2.

[0129] Although several implementations have been described, it is understood that the spirit and scope of this disclosure is not to be construed as limiting the scope of the present invention. It will be understood that various modifications may be made without departing from the scope of the invention. [1] 1. A membrane reformer for producing hydrogen, comprising: A plurality of membrane reactors are provided, Each membrane reactor is a feed conduit as an outer conduit of the membrane reactor, which receives hydrocarbons and steam into a region outside the tubular membrane within the feed conduit; a catalyst disposed in the region within the feed conduit outside the tubular membrane for converting the hydrocarbons to hydrogen and carbon dioxide, the catalyst comprising a steam reforming catalyst; a tubular membrane in the feed conduit for diffusing the hydrogen from the region through the tubular membrane to a bore of the tubular membrane, the region being a retentate side of the tubular membrane for discharging a retentate comprising carbon dioxide, and the bore being a permeate side of the tubular membrane for discharging a permeate comprising hydrogen; an insert tube disposed within the bore to facilitate the flow of a sweep gas through the bore in a direction opposite to the flow of hydrocarbons and steam in the region outside the tubular membrane; Membrane reformer. [2] The tubular membrane comprises two longitudinally joined tubular membranes. The membrane reformer according to [1] above. [3] The outer diameter of the supply conduit is in the range of 15 millimeters (mm) to 50 mm; the wall thickness of the supply conduit is in the range of 1 mm to 3 mm; The outer diameter of the tubular membrane is in the range of 8 mm to 30 mm; The wall thickness of the tubular membrane is in the range of 1 mm to 3.5 mm; The outer diameter of the insertion tube is in the range of 4 mm to 15 mm, The wall thickness of the insertion tube is in the range of 0.3 mm to 1.5 mm. The membrane reformer according to [1] above. [4] the catalyst is not in contact with the tubular membrane; the catalyst comprises a water gas shift (WGS) catalyst; The membrane reformer according to [1] above. [5] the plurality of membrane reactors comprises a first membrane reactor and a second membrane reactor; the membrane reformer comprises an interconnecting conduit connecting the feed conduit of the first membrane reactor to the feed conduit of the second membrane reactor; the feed conduit of the second membrane reactor receives the retentate from the first membrane reactor via the interconnecting conduit; The membrane reformer according to [1] above. [6] The residue discharged from the first membrane reactor to the feed conduit of the second membrane reactor comprises unreacted steam and hydrocarbons in the first membrane reactor. The membrane reformer according to [5] above. [7] the hydrocarbons include methane, liquefied petroleum gas (LPG), or a mixture of C1 to C5 hydrocarbons, or any combination thereof; The production capacity of the membrane reformer is 10,000 standard cubic meters of hydrogen per hour (Nm 3 / hr) is less than The membrane reformer according to [1] above. [8] The production capacity of the membrane reformer is 1,000 Nm of hydrogen. 3 / hr or less, The membrane reformer according to [1] above. [9] an electric heater for providing heat to the plurality of membrane reactors so that the operating temperature of the membrane reformer is less than 650°C; The membrane reformer according to [1] above.

[10] a heat distribution plate in contact with the plurality of membrane reactors; The electric heater is disposed on the heat distribution plate. The membrane reformer according to [9] above.

[11] The electric heater includes a strip heater. The membrane reformer according to

[10] above.

[12] The plurality of membrane reactors comprises membrane reactors operatively arranged in parallel, in series, or both. The membrane reformer according to [1] above.

[13] The plurality of membrane reactors comprises at least 30 membrane reactors. The membrane reformer according to [1] above.

[14] The at least 30 membrane reactors are arranged in a box having a width of less than 5 meters (m), a length of less than 5 m, and a height of less than 5 m. The membrane reformer according to

[13] above.

[15] At least one of the plurality of membrane reactors is provided with a pre-reforming catalyst at an inlet portion of a feed pipe; The membrane reformer according to [1] above.

[16] At least one of the plurality of membrane reactors is provided with a dry reforming catalyst at an outlet portion of a feed pipe; The membrane reformer according to [1] above.

[17] 1. A method for producing hydrogen, comprising: supplying hydrocarbons and steam to a membrane reformer comprising a plurality of membrane reactors; converting hydrocarbons into hydrogen and carbon dioxide via a catalyst disposed outside tubular membranes in the plurality of membrane reactors, the catalyst comprising a steam reforming catalyst; allowing hydrogen passing through the tubular membranes of the plurality of membrane reactors to diffuse into the bores of each of the tubular membranes; flowing a sweep gas through each of the bores to move hydrogen in a direction counter to the flow of hydrocarbons and steam outside the tubular membrane; discharging hydrogen as permeate from each of said bores together with said sweep gas; and discharging the carbon dioxide outside the tubular membranes as a residue from the plurality of membrane reactors. method.

[18] The residue comprises unreacted vapors, The catalyst comprises a water gas shift (WGS) catalyst. The method described in

[17] above.

[19] the catalyst is not in contact with the tubular membrane; The method described in

[17] above.

[20] the step of displacing hydrogen within each bore with the sweep gas increases hydrogen permeation through the tubular membrane to the outside of the tubular membrane; The method described in

[17] above.

[21] electrically heating the plurality of membrane reactors; The operating temperature of the plurality of membrane reactors is less than 650°C. The method described in

[17] above.

[22] the step of electrically heating the plurality of membrane reactors comprises electrically heating the plurality of membrane reactors through a heat distribution plate in contact with the plurality of membrane reactors; The method described in

[21] above.

[23] an operating pressure outside the tubular membranes in the plurality of membrane reactors is in the range of 10 bar to 50 bar; The operating pressure of each bore is in the range of 1 bar to 5 bar. The method described in

[17] above.

[24] The hydrogen production step is 5,000 standard cubic meters per hour (Nm 3 / hr), The method described in

[17] above.

[25] the step of diffusing the hydrogen through the tubular membrane is simultaneous with the step of converting the hydrocarbon to hydrogen. The method described in

[17] above.

[26] flowing a retentate from a first membrane reactor of the plurality of membrane reactors to a second membrane reactor of the plurality of membrane reactors; the residue from the first membrane reactor comprises steam and hydrocarbons unreacted in the first membrane reactor; The method described in

[17] above.

[27] discharging hydrogen as permeate from at least one of the bores together with the sweep gas as product hydrogen from the membrane reformer; the product hydrogen comprises at least 90 mole % hydrogen on a sweep gas-free basis; The method described in

[17] above.

[28] the sweep gas comprises steam; the method comprising condensing the sweep gas in the product hydrogen to remove the sweep gas as liquid water from the product hydrogen; The method described in

[27] above.

[29] 1. A method for producing hydrogen, comprising: Producing hydrogen using a membrane reformer including a plurality of membrane reactors, each membrane reactor including an outer tube and a tubular membrane within the outer tube, and the producing step is performed by each membrane reactor; converting hydrocarbons into hydrogen and carbon dioxide in the presence of steam in a region within the outer tube outside the tubular membrane via a catalyst disposed in the region, the catalyst comprising a reforming catalyst; diffusing hydrogen from the region through the tubular membrane to a bore of the tubular membrane, the region being on the retentate side of the tubular membrane and the bore being on the permeate side of the tubular membrane; venting carbon dioxide from the region; flowing a sweep gas through the bore to displace hydrogen from the bore in a direction opposite to the flow of the hydrocarbons in the region outside the tubular membrane; and discharging hydrogen and sweep gas from the bore. method.

[30] The tubular membrane comprises two longitudinally connected tubular membranes. The method described in

[29] above.

[31] facilitating flow of the sweep gas in the opposing directions through an insert tube disposed within the bore. The method described in

[29] above.

[32] venting the carbon dioxide comprises venting unreacted steam and the carbon dioxide from the region; The catalyst comprises a water gas shift (WGS) catalyst. The method described in

[29] above.

[33] the operating temperature of the membrane reactor is less than 650°C; the operating pressure outside the tubular membrane in the outer tube is in the range of 10 bar to 50 bar; The operating pressure of the bore is in the range of 1 bar to 5 bar. The method described in

[29] above.

[34] The outer diameter of the outer tube is in the range of 15 millimeters (mm) to 50 mm, The wall thickness of the outer tube is in the range of 1 mm to 3 mm, The outer diameter of the tubular membrane is in the range of 8 mm to 30 mm; The wall thickness of the tubular membrane is in the range of 1 mm to 3.5 mm. The method described in

[29] above.

[35] flowing carbon dioxide discharged from the region of a first membrane reactor of the plurality of membrane reactors to the region of a second membrane reactor of the plurality of membrane reactors; the carbon dioxide from the region of the first membrane reactor includes unreacted steam and unreacted hydrocarbons; The method described in

[29] above.

[36] Discharging hydrogen from the membrane reformer as product hydrogen; the product hydrogen comprises at least 90 mole % hydrogen on a sweep gas-free basis; The method described in

[29] above.

[37] the sweep gas comprises steam; The product hydrogen comprises at least 90 mol% on a dry basis; The method described in

[36] above.

[38] producing hydrogen comprises converting hydrocarbons to methane using at least one of the plurality of membrane reactors with a pre-reforming catalyst in an inlet portion of the outer tube; The method described in

[29] above.

[39] producing hydrogen comprises converting hydrocarbons into hydrogen using at least one of the plurality of membrane reactors with a dry reforming catalyst in an outlet portion of the outer tube; The method described in

[29] above.

Claims

1. 1. A membrane reformer for producing hydrogen, comprising: Each membrane reactor of the plurality of membrane reactors, each having an outer conduit, a feed conduit as the outer conduit of the membrane reactor, which receives hydrocarbons and steam into a region outside the tubular membrane within the feed conduit; a catalyst disposed in the region within the feed conduit outside the tubular membrane for converting the hydrocarbons into hydrogen and carbon dioxide, the catalyst comprising a steam reforming catalyst, the catalyst not in contact with the tubular membrane; a tubular membrane in the feed conduit for diffusing the hydrogen from the region through the tubular membrane to a bore of the tubular membrane, the region being a retentate side of the tubular membrane for discharging a retentate comprising carbon dioxide, and the bore being a permeate side of the tubular membrane for discharging a permeate comprising hydrogen; an insert tube disposed within the bore to facilitate the flow of a sweep gas through the bore in a direction counter to the flow of hydrocarbons and vapors in the region outside the tubular membrane; an interconnecting conduit connecting the feed conduit of a first membrane reactor of the plurality of membrane reactors to the feed conduit of a second membrane reactor of the plurality of membrane reactors and delivering a retentate discharged from the first membrane reactor to the second membrane reactor; a heat distribution plate contacting an outer surface of the feed conduit of a third membrane reactor of the plurality of membrane reactors and contacting an outer surface of the feed conduit of a fourth membrane reactor of the plurality of membrane reactors; an electric heater disposed on the heat distribution plate; Equipped with Membrane reformer.

2. the tubular membrane comprises two longitudinally joined tubular membranes; The membrane reformer of claim 1 .

3. the outer diameter of the supply conduit is in the range of 15 millimeters (mm) to 50 mm; the wall thickness of the supply conduit is in the range of 1 mm to 3 mm; the outer diameter of the tubular membrane is in the range of 8 mm to 30 mm; the wall thickness of the tubular membrane is in the range of 1 mm to 3.5 mm; The outer diameter of the insertion tube is in the range of 4 mm to 15 mm; The wall thickness of the insertion tube is in the range of 0.3 mm to 1.5 mm. However, the inner diameter of the supply conduit is the outer diameter minus twice its wall thickness, the inner diameter of the supply conduit is greater than the outer diameter of the tubular membrane and is the outer diameter minus twice its wall thickness, and the inner diameter of the tubular membrane is greater than the outer diameter of the insertion tube. The membrane reformer of claim 1 .

4. the catalyst is coated on the inner surface of the supply conduit; the catalyst comprises a water-gas shift (WGS) catalyst; the feed conduit of a particular membrane reactor among the plurality of membrane reactors is not the feed conduit of another membrane reactor among the plurality of membrane reactors; The membrane reformer of claim 1 .

5. the catalyst is washcoated onto the interior surface of the supply conduit; the plurality of membrane reactors comprises the first membrane reactor and the second membrane reactor; the feed conduit of the second membrane reactor receives the retentate from the first membrane reactor via the interconnecting conduit; The membrane reformer of claim 1 .

6. the residue discharged from the first membrane reactor to the feed conduit of the second membrane reactor comprises unreacted steam and hydrocarbons in the first membrane reactor; The membrane reformer of claim 1 .

7. the hydrocarbons include methane, liquefied petroleum gas (LPG), or a mixture of C1 to C5 hydrocarbons, or any combination thereof; The membrane reformer has a production capacity of 10,000 standard cubic meters of hydrogen per hour (Nm ３ / hr) or less, The membrane reformer of claim 1 .

8. The production capacity of the membrane reformer is 1,000 Nm of hydrogen. ３ / hr or less, The membrane reformer of claim 1 .

9. The electric heater includes a strip heater. The membrane reformer of claim 1 .

10. the electric heater provides heat to at least some of the plurality of membrane reactors through the heat distribution plate; The operating temperature of the film reformer is less than 650°C. The membrane reformer of claim 1 .

11. The plurality of membrane reactors comprises membrane reactors operably arranged in series. The membrane reformer of claim 1 .

12. The plurality of membrane reactors comprises at least 30 membrane reactors. The membrane reformer of claim 1 .

13. the at least 30 membrane reactors comprising a first module of membrane reactors and a second module of membrane reactors; The at least 30 membrane reactors have a width of less than 5 meters (m), a length of less than 5 m, and and placed in a box having a height of less than 5 m, The membrane reformer of claim 12.

14. At least one of the plurality of membrane reactors is provided with a dry reforming catalyst at an outlet portion of a feed pipe. The membrane reformer of claim 1 .

15. The dry reforming catalyst comprises a precious metal-based catalyst or nickel-molybdenum (Ni-Mo) on magnesium oxide (MgO); 15. The membrane reformer of claim 14.

16. 1. A method for producing hydrogen, comprising: supplying hydrocarbons and steam to a membrane reformer comprising a plurality of membrane reactors, each of the plurality of membrane reactors having an outer conduit with a tubular membrane disposed therein and a catalyst disposed outside the tubular membrane, the catalyst not in contact with the tubular membrane; converting the hydrocarbons into hydrogen and carbon dioxide via the catalyst outside tubular membranes in the plurality of membrane reactors, the catalyst comprising a steam reforming catalyst; allowing hydrogen passing through the tubular membranes of the plurality of membrane reactors to diffuse into the bores of each of the tubular membranes; flowing a sweep gas through each of the bores to move hydrogen in a direction counter to the flow of hydrocarbons and steam outside the tubular membrane; discharging hydrogen as permeate from each of said bores together with said sweep gas; Discharging carbon dioxide outside the tubular membranes as a retentate from the plurality of membrane reactors; flowing a retentate from a first membrane reactor of the plurality of membrane reactors to a second membrane reactor of the plurality of membrane reactors; electrically heating a third membrane reactor and a fourth membrane reactor of the plurality of membrane reactors via a heat distribution plate contacting an outer surface of the outer conduit of the third membrane reactor and contacting an outer surface of the outer conduit of the fourth membrane reactor; method.

17. The residue comprises unreacted vapors, The catalyst comprises a water gas shift (WGS) catalyst.

17. The method of claim 16.

18. the catalyst is coated on the inner surface of the outer conduit of each of the plurality of membrane reactors; the residue from the first membrane reactor comprises steam and hydrocarbons unreacted in the first membrane reactor; 17. The method of claim 16.

19. the step of displacing hydrogen within each bore with the sweep gas increases hydrogen permeation through the tubular membrane to the outside of the tubular membrane; 17. The method of claim 16.

20. electrically heating the plurality of membrane reactors; The operating temperature of the plurality of membrane reactors is less than 650°C.

17. The method of claim 16.

21. the step of electrically heating the plurality of membrane reactors comprises the step of electrically heating the third membrane reactor and the fourth membrane reactor through the heat distribution plate; 21. The method of claim 20.

22. an operating pressure outside the tubular membranes in the plurality of membrane reactors is in the range of 10 bar to 50 bar; the operating pressure of each bore is in the range of 1 bar to 5 bar; 17. The method of claim 16.

23. The step of producing hydrogen is carried out at a rate of 5,000 standard cubic meters per hour (Nm ３ / hr) 17. The method of claim 16.

24. the step of diffusing the hydrogen through the tubular membrane is simultaneous with the step of converting the hydrocarbon to hydrogen.

17. The method of claim 16.

25. the catalyst is washcoated on the inner surface of the outer conduit of each of the membrane reactors of the plurality of membrane reactors; 17. The method of claim 16.

26. discharging hydrogen as permeate from at least one of the bores together with the sweep gas as product hydrogen from the membrane reformer; the product hydrogen comprises at least 90 mole % hydrogen on a sweep gas-free basis; 17. The method of claim 16.

27. the sweep gas comprises steam; the method comprising condensing the sweep gas in the product hydrogen to remove the sweep gas as liquid water from the product hydrogen; 27. The method of claim 26.

28. 1. A method for producing hydrogen, comprising: A step of producing hydrogen using a membrane reformer including a plurality of membrane reactors, each membrane reactor including an outer tube, a catalyst within the outer tube, and a tubular membrane within the outer tube, the producing step including: converting hydrocarbons into hydrogen and carbon dioxide in the presence of steam via the catalyst disposed in a region within the outer tube outside the tubular membrane, the catalyst comprising a reforming catalyst, the catalyst not in contact with the tubular membrane; diffusing hydrogen from the region through the tubular membrane to a bore of the tubular membrane, the region being on the retentate side of the tubular membrane and the bore being on the permeate side of the tubular membrane; venting carbon dioxide from the region; flowing a sweep gas through the bore to displace hydrogen from the bore in a direction opposite to the flow of the hydrocarbons in the region outside the tubular membrane; and discharging hydrogen and a sweep gas from the bore; from the region of a first membrane reactor of the plurality of membrane reactors to one of the plurality of membrane reactors. flowing the discharged carbon dioxide into said region of the second membrane reactor; electrically heating a third membrane reactor and a fourth membrane reactor of the plurality of membrane reactors via a heat distribution plate contacting an outer surface of the outer tube of the third membrane reactor and contacting an outer surface of the outer tube of the fourth membrane reactor; method.

29. The tubular membrane comprises two longitudinally connected tubular membranes.

29. The method of claim 28.

30. facilitating flow of the sweep gas in the opposing directions through an insert tube disposed within the bore.

29. The method of claim 28.

31. venting the carbon dioxide comprises venting unreacted steam and the carbon dioxide from the region; The catalyst comprises a water gas shift (WGS) catalyst.

29. The method of claim 28.

32. the operating temperature of the membrane reactor is less than 650°C; an operating pressure outside the tubular membrane within the outer tube ranging from 10 bar to 50 bar; the operating pressure in said bore is in the range of 1 bar to 5 bar; the carbon dioxide from the region of the first membrane reactor includes unreacted steam and unreacted hydrocarbons; 29. The method of claim 28.

33. the outer diameter of the outer tube is in the range of 15 millimeters (mm) to 50 mm; The wall thickness of the outer tube is in the range of 1 mm to 3 mm; the outer diameter of the tubular membrane is in the range of 8 mm to 30 mm; The wall thickness of the tubular membrane is in the range of 1 mm to 3.5 mm. However, the inner diameter of the outer tube, which is the outer diameter of the outer tube minus twice its wall thickness, is greater than the outer diameter of the tubular membrane.

29. The method of claim 28.

34. The catalyst is coated on the inner surface of the outer tube of each of the plurality of membrane reactors.

29. The method of claim 28.

35. Discharging hydrogen from the membrane reformer as product hydrogen; the product hydrogen comprises at least 90 mole % hydrogen on a sweep gas-free basis; The outer tube of a specific membrane reactor among the plurality of membrane reactors is not the outer tube of another membrane reactor among the plurality of membrane reactors; 29. The method of claim 28.

36. the sweep gas comprises steam; The product hydrogen comprises at least 90 mol% on a dry basis.

36. The method of claim 35.

37. producing hydrogen comprises converting hydrocarbons into hydrogen using at least one of the plurality of membrane reactors with a dry reforming catalyst in an outlet portion of the outer tube; 29. The method of claim 28.

38. Dry reforming catalysts include nickel molybdenum (Ni-Mo) on magnesium oxide (MgO) or precious metal-based catalysts; 38. The method of claim 37.

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