Systems and methods for generating, storing and transporting hydrogen

Abstract

The present disclosure refers to systems and methods for generating, storing and transporting hydrogen. In an exemplary embodiment, the reactor system includes a fluidized bed combustor configured for oxidation of reduced metal oxides and heat generation with no significant greenhouse gas emissions and / or emissions that can be easily captured. The reactor system also includes a liquid organic hydrogen carrier dehydrogenation reactor. The fluidized bed combustor is operatively linked to the liquid organic hydrogen carrier dehydrogenation reactor. Advantageously, at least a portion of the heat generated by the fluidized bed combustor can be transferred to the liquid organic hydrogen carrier dehydrogenation reactor. In this manner, both hydrogen production and transportation are energy efficient, low carbon intensity, and cost effective.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Patent Application No. 17 / 568,409, filed January 4, 2022, the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to systems and methods for generating, storing and / or transporting hydrogen. [Background technology]

[0003] Hydrogen is one of the more important clean energy options of the future. Unfortunately, storing and transporting hydrogen fuel from the point of generation, e.g., hydrogen gas stations or other storage facilities, is often inefficient and / or costly today. This issue is well-understood as one of the significant barriers to large-scale deployment of hydrogen. Storage of hydrogen in liquid organic hydrogen carrier (LOHC) systems has numerous advantages over traditional storage systems. Most importantly, storing and transporting hydrogen in the form of LOHC systems allows the use of existing fuel infrastructure. From a thermodynamic perspective, storage of hydrogen in LOHC systems requires an exothermic hydrogenation step and an endothermic dehydrogenation step. Summary of the Invention

[0004] The performance of LOHC dehydrogenation units, especially at higher hydrogen release rates, strongly depends on the applied reactor configuration. What is needed is a solution that allows efficient hydrogen production with low carbon intensity, without requiring costly equipment, such as air separation units or amine carbon absorption units. This would be further advantageous if such a solution could be easily coupled with energy-efficient and cost-effective storage and transportation methods.

[0005] Advantageously, the present application relates to new systems and methods that allow efficient hydrogen production without the need for costly equipment, such as air separation units or amine carbon absorption units, and avoid CO2 greenhouse gas emissions in the system. The solutions described herein may be coupled with energy-efficient, low-carbon intensity and cost-effective storage and / or transportation methods or systems of hydrogen.

[0006] In one embodiment, the present application relates to a reactor system including a fluidized bed combustor configured for oxidation of reduced metal oxides and heat generation without emitting the greenhouse gas CO2. The reactor system also includes a liquid organic hydrogen carrier dehydrogenation (LOHD) reactor. The fluidized bed combustor is operatively associated with the liquid organic hydrogen carrier dehydrogenation reactor such that at least a portion of the heat generated by the fluidized bed combustor can be transferred to the liquid organic hydrogen carrier dehydrogenation reactor.

[0007] In another embodiment, the present application relates to a method comprising oxidizing a reduced metal oxide in the presence of air, oxygen-depleted air, and under conditions suitable to produce an oxidized metal oxide. The oxidizing may be carried out in a fluidized bed combustor. The liquid organic hydrogen carrier is dehydrogenated in the dehydrogenation reactor under dehydrogenation conditions to form H2 and an at least partially dehydrogenated liquid organic hydrogen carrier. The fluidized bed combustor is operatively associated with the liquid organic hydrogen carrier dehydrogenation reactor such that at least a portion of any heat generated by the fluidized bed combustor may be transferred to the liquid organic hydrogen carrier dehydrogenation reactor.

[0008] These and other objects, features and advantages of the exemplary embodiments of the present disclosure will become apparent from the following detailed description of exemplary embodiments of the present disclosure, when read in conjunction with the appended claims.

[0009] The various embodiments of the present disclosure, together with further objects and advantages, may best be understood by reference to the following description taken in conjunction with the accompanying drawings, in which: [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 illustrates an exemplary reactor system. [Diagram 2] FIG. 1 illustrates the oxidation of fuel in a reducer and heat generation in a combustor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The following description of the embodiments provides non-limiting representative examples with reference to figures that specifically describe the features and teachings of various aspects of the present invention. It should be understood from the description of the embodiments that the described embodiments can be implemented separately or in combination with other embodiments. Those skilled in the art who review the description of the embodiments should be able to learn and understand the various aspects of the invention described. The description of the embodiments should facilitate understanding of the present invention to the extent that other implementations that are not specifically covered but are within the knowledge of those skilled in the art who read the description of the embodiments will be understood to be consistent with the application of the present invention.

[0012] This application relates to reactor systems and methods for generating, for example, H2 and at least partially dehydrogenated liquid organic hydrogen carriers. The reactor systems described may be used in the methods described herein, as well as other applicable methods. The reactor systems generally include a fluidized bed combustor, which may be configured in a manner that one of ordinary skill in the art would understand. In some embodiments, the fluidized bed combustor is configured to oxidize reduced metal oxides.

[0013] The particular size, type and design of the fluidized bed combustor may vary depending on the desired load, catalyst, reaction conditions, products, etc. Typically, the fluidized bed combustor is operatively associated with a liquid organic hydrogen carrier dehydrogenation reactor. The particular size, type and design of the liquid organic hydrogen carrier dehydrogenation reactor may also vary depending on the reactants, conditions, desired products, etc. Typically, the fluidized bed combustor is operatively associated with the liquid organic hydrogen carrier dehydrogenation reactor, such that at least a portion of the heat generated by the fluidized bed combustor, up to substantially all or all of the heat, may be transferred to the liquid organic hydrogen carrier dehydrogenation reactor. This advantageously contributes to the high energy efficiency of the systems and methods described herein.

[0014] As noted above, the fluidized bed combustor is operatively coupled to the liquid organic hydrogen carrier dehydrogenation reactor in a manner that transfers at least a portion, and up to nearly all, or all, of the heat generated. Of course, the specific configuration of the coupled connection may vary depending on the specifications of each reactor and other factors. In one embodiment, the operative connection allows the liquid organic hydrogen carrier dehydrogenation reactor to be submerged within the fluidized bed combustor.

[0015] The above reactor system may have other devices connected depending on the desired use of the system. In some embodiments, the reducer may be operatively linked to a fluidized bed combustor. In this manner, metal oxides, such as but not limited to Fe2O3, may be reduced to, for example, FeO and fed to the fluidized bed combustor. In the combustor, the reduced metal oxides, such as FeO, may react with air to produce air depleted of O2. While the combustor oxidizes the metal oxides, an operably connected liquid organic hydrogen carrier dehydrogenation reactor is operating. The liquid organic hydrogen carrier dehydrogenation reactor may be operated under conditions to dehydrogenate the liquid organic hydrogen carrier to form H2 and at least a partially dehydrogenated liquid organic hydrogen carrier.

[0016] The liquid organic hydrogen carrier is not particularly limited and may include, for example, perhydrodibenzyltoluene, perhydrobenzyltoluene, methyl-cyclohexane, cyclohexane, N-ethylcarbazole, ammonia borane, ammonia, formic acid, siloxane, and any mixture thereof. In some embodiments, the liquid organic hydrogen carrier may be perhydrodibenzyltoluene (H18-DBT), which may release up to 9 H2 for every mole of H18-DBT in the hydrogen carrier dehydrogenation reactor. Because this is an endothermic reaction that requires heat, it is advantageous to have the liquid organic hydrogen carrier dehydrogenation reactor interfaced to a combustor so that at least a portion of the heat from the combustor can be used for the dehydrogenation reaction.

[0017] The reactor system may connect the liquid organic hydrogen carrier dehydrogenation reactor to a separator if hydrogen separation is desired. Such separators may vary depending on the liquid organic hydrogen carrier used and the design and conditions of the dehydrogenation reactor. After separation, if desired, the hydrogen may be transported via an operably connected transportation system, for example to a hydrogen storage station, or the hydrogen may be used on-site as a fuel source.

[0018] In another embodiment, the present application relates to a method that may use the reactor system described above or some alternatives. The method generally includes oxidizing a reduced metal oxide in the presence of air, oxygen-depleted air, and conditions suitable to produce an oxidized metal oxide. As noted above, an exemplary embodiment may use an iron oxide reducing agent. Generally, the oxidizing step may be carried out in a fluidized bed combustor. As with the reactor system, the liquid organic hydrogen carrier may include perhydrodibenzyltoluene, which may be dehydrogenated in any convenient reactor, such as a liquid organic hydrogen carrier dehydrogenation reactor, under dehydrogenation conditions sufficient to form H2 and dibenzyltoluene.

[0019] The H2 and the at least partially dehydrogenated liquid organic hydrogen carrier, such as dibenzyltoluene, can be separated in any convenient manner. The H2 can then be used, transported and / or stored as desired.

[0020] FIG. 1 shows a multi-tube LOHC reactor submerged in a fluidized bed combustor. In this approach, at least a portion, up to nearly all or all of the heat generated from the oxidation can be transferred through one or more tube walls (or in some other convenient manner depending on the configuration) to obtain energy for the dehydrogenation reaction. With this configuration, a carbonaceous fuel, e.g., natural gas, is fed into the reducer to reduce the metal oxides and generate a pure or nearly pure CO2 stream after condensation and separation of H2O. This CO2 stream is immediately available for sequestration or other utilization without the need for further gas phase separation. Me is a metal or mixture of metals that can be reduced by a carbonaceous fuel and subsequently oxidized by air. Such metals include Fe, Co, In, Mn, Sn, Zn, Cu, W, and combinations thereof.

[0021] Representative reductor and combustor reactions are shown in Figure 2. Although Figure 2 is shown for iron oxide, it should be recognized that many other metal oxides may be useful.

[0022] The reducer reactor typically operates at 400-1200 °C. The combustor reactor usually operates at a higher temperature than the reducer, 0-400 °C, depending on the type of metal(s) used in the system. The reduction reaction in the reducer is typically endothermic. A portion of the reduced metal oxides from the reducer are sent directly to the combustor for oxidation with oxygen in the supply air. The heat released from the exothermic reaction in the combustor is used to compensate for the heat required for the dehydrogenation reaction of the LOHC.

[0023] The metals and metal oxides in the system are typically in the form of porous spherical particles in the range of 0.1 to 10 mm. Fluidized bed combustors operate in a bubble and / or turbulent regime to efficiently transfer high heat through embedded tube buddles containing the dehydrogenation catalyst. EXAMPLES

[0024] [Example 1] Dehydrogenation of perhydrodibenzyltoluene (H18-DBT)

[0025] [ka]

[0026] Dibenzyltoluene is a commercially available fluid, sometimes sold by Sasol as an isometric mixture of dibenzyltoluene under the trade name Marlotherm SH. H0-DBT is reported to exhibit excellent thermal properties and a high hydrogen storage capacity of 6.2 wt%.

[0027] As a liquid organic hydrogen carrier, hydrogen is loaded into H0-DBT, converted to H18-DBT at the hydrogen production site, and then transported to the destination where hydrogen is required. The H0-DBT / H18-DBT LOHC system has diesel-like properties and may be handled by existing industrial infrastructure for fuels. On demand, hydrogen can be released from H18-DBT by catalytic dehydrogenation using suitable catalysts at temperatures between 200 and 400 °C. This dehydrogenation reaction is highly endothermic, with a reaction enthalpy of 65.4 kJ / mol-H2. The process configuration in Figure 1 provided an efficient means of heat supply for the reaction with a high heat transfer rate.

[0028] [Example 2] Dehydrogenation of cyclohexane

[0029] [ka]

[0030] The LOHC compound cyclohexane has a hydrogen storage capacity of 7.19 wt % and is a liquid at room temperature.

[0031] As a liquid organic hydrogen carrier, hydrogen is loaded into benzene, which is converted to cyclohexane at a hydrogen production site and then transported to the destination where hydrogen is required. On demand, hydrogen can be released from cyclohexane by catalytic dehydrogenation using suitable catalysts at temperatures between 200 and 400 °C. This dehydrogenation reaction is highly endothermic, with a reaction enthalpy of 68.8 kJ / mol-H2. The process configuration in Figure 1 provides an efficient means of heat supply for the reaction with a high heat transfer rate.

[0032] [Example 3] Dehydrogenation of toluene

[0033] [ka]

[0034] Methylcyclohexane has a hydrogen storage capacity of 6.2 wt % and is in a liquid state at ambient conditions.

[0035] As a liquid organic hydrogen carrier, hydrogen is loaded into toluene, which is converted to methylcyclohexane at a hydrogen production site and then transported to the destination where hydrogen is required. On demand, hydrogen can be released from methylcyclohexane by catalytic dehydrogenation using suitable catalysts at temperatures between 100 and 400 °C. This dehydrogenation reaction is highly endothermic, with a reaction enthalpy of 68.3 kJ / mol-H2. The process configuration in Figure 1 provides an efficient means of heat supply for the reaction with a high heat transfer rate.

[0036] In most pure hydrocarbon LOHC systems, the lower the operating pressure, the lower the operating temperature, which allows for complete conversion of the dehydrogenation reaction. Therefore, from a thermodynamic point of view, the lowest possible system pressure should be selected for the dehydrogenation. However, this is not always beneficial to the catalyst and may favor side reactions and catalyst deactivation.

[0037] In the preceding description, various embodiments have been described with reference to the accompanying drawings. However, it will be apparent that various modifications and changes may be made thereto, and additional embodiments may be practiced, without departing from the broad scope of the invention as set forth in the following claims. The specification and drawings are therefore to be regarded as illustrative rather than in a restrictive sense.

Claims

1. A fluidized bed combustor configured for the oxidation of a reduced metal oxide, and a reactor system including a dehydrogenation reactor for a liquid organic hydrogen carrier, wherein the fluidized bed combustor is operably linked to the dehydrogenation reactor for the liquid organic hydrogen carrier, such that at least a portion of the heat generated by the fluidized bed combustor can be transferred to the dehydrogenation reactor for the liquid organic hydrogen carrier, the dehydrogenation reactor for the liquid organic hydrogen carrier is a closed system with respect to the fluidized bed combustor, and the dehydrogenation reactor for the liquid organic hydrogen carrier is submerged in and surrounded by the fluidized bed combustor, the reactor system.

2. The reactor system according to claim 1, further including a reducer operably linked to the fluidized bed combustor, such that a metal oxide is reduced and can be supplied to the fluidized bed combustor.

3. The reactor system according to claim 1, wherein there is substantially no greenhouse gas emission from the fluidized bed combustor to the environment.

4. The reactor system according to claim 1, wherein the dehydrogenation reactor for the liquid organic hydrogen carrier is configured to be connected to a separator.

5. The reactor system according to claim 4, further including a transport system operably connected to the separator.

6. In the presence of air, a step of oxidizing a reduced metal oxide under conditions suitable for producing air depleted in oxygen and an oxidized metal oxide, the oxidizing step comprising being carried out in a fluidized bed combustor; and Under dehydrogenation conditions, in a liquid organic hydrogen carrier dehydrogenation reactor, dehydrogenating a liquid organic hydrogen carrier to form H ２ and at least partially dehydrogenated liquid organic hydrogen carrier, the method comprising: the fluidized bed combustor being thermally linked to the dehydrogenation reactor for the liquid organic hydrogen carrier, such that at least a portion of the heat generated by the fluidized bed combustor can be transferred to the dehydrogenation reactor for the liquid organic hydrogen carrier, and the dehydrogenation reactor for the liquid organic hydrogen carrier being a closed system with respect to the fluidized bed combustor, and the dehydrogenation reactor for the liquid organic hydrogen carrier being submerged in and surrounded by the fluidized bed combustor, the method.

7. Fe ２ O ３ The method according to claim 6, further comprising the step of reducing the metal oxide containing FeO to form the reduced metal oxide.

8. The method according to claim 6, wherein the liquid organic hydrogen carrier is selected from perhydrodibenzyltoluene, perhydrobenzyltoluene, methyl - cyclohexane, cyclohexane, N - ethylcarbazole, ammonia borane, siloxane, and any mixture thereof.

9. The method according to claim 6, wherein the liquid organic hydrogen carrier is perhydrodibenzyltoluene.

10. wherein the perhydrodibenzyltoluene is dehydrogenated in the liquid organic hydrogen carrier dehydrogenation reactor under conditions sufficient to form H ２ and dibenzyltoluene, according to claim 9, the method described.

11. H ２ The method according to claim 9, further comprising a step of separating the perhydrodibenzyltoluene.

12. H ２ The method according to claim 6, further comprising a step of separating said liquid organic hydrogen carrier that has been at least partially dehydrogenated.

13. The foregoing H ２ The method according to claim 12, further comprising the step of transporting

14. The foregoing H ２ The method according to claim 11, further comprising a step of transporting the foregoing H.

Images