WO2005099886A1

WO2005099886A1 - Catalyst bed with integrated heatings elements

Info

Publication number: WO2005099886A1
Application number: PCT/US2005/012764
Authority: WO
Inventors: Jerry M. Rovner; James F. Stevens
Original assignee: Texaco Development Corporation
Priority date: 2004-04-19
Filing date: 2005-04-14
Publication date: 2005-10-27
Also published as: TW200603893A

Abstract

Method and apparatus (100) for generating hydrogen which include heating a reforming reactant with heat derived from a reactant heater (120). Said heated reactant that is reformed in a catalyst bed (130) comprising a reforming catalyst and a carbon dioxide fixing material. Regeneration heat is produced and the catalyst bed (130) is heated to a regeneration temperature to release fixed carbon dioxide. A portion of the regeneration heat is utilized for heating the reactant heater (120), pre-heating a reforming reactant for delivery to the reactant heater (120), pre-heating an oxidant for delivery to the reactant heater (120) or to a regeneration heater (110) and/or heating a reforming reactant to a reforming reactant for delivery to a catalyst bed (130). The regeneration heat can be produced in a regeneration heater (110) and/or within the catalyst bed (130).

Description

CATALYST BED WITH INTEGRATED HEATING ELEMENTS

FIELD OF THE INVENTION

The present invention relates to the field of hydrogen generation such as tlirough fuel processing wherein a hydrocarbon-based fuel is converted to a hydrogen- enriched reformate for ultimate use in a hydrogen-consuming device and/or process. The fuel processing apparatus and method of the present invention provide a hydrogen-rich reformate of high purity by utilizing absorption enhanced reforming wherein a by-product, such as carbon dioxide, is absorbed from the product stream to shift the conversion reaction equilibrium toward the production of higher levels of hydrogen and lower levels of by-products.

BACKGROUND OF THE INVENTION

Hydrogen is utilized in a wide variety of industries ranging from aerospace to food production to oil and gas production and refining. Hydrogen is used in these industries as a propellant, an atmosphere, a carrier gas, a diluent gas, a fuel component for combustion reactions, a fuel for fuel cells, as well as a reducing agent in numerous chemical reactions and processes. In addition, hydrogen is being considered as an alternative fuel for transportation and power generation because it is renewable, abundant, efficient, and unlike other alternatives, produces zero emissions. While there is wide-spread consumption of hydrogen and great potential for even more, a disadvantage which inhibits further increases in hydrogen consumption is the absence of a hydrogen infrastructure that can provide widespread storage and distribution. One way to overcome this difficulty is distributed generation of hydrogen, wherein fuel reformers or fuel processors are used to convert hydrocarbon- based fuels to hydrogen-rich refomiate. Fuel reforming processes, such as steam reforming, partial oxidation, and autothermal reforming, can be used to convert hydrocarbon-based fuels such as natural gas, LPG, gasoline, and diesel, into hydrogen-rich reformate at a site where the hydrogen is needed. However, in addition to the desired hydrogen product, fuel reformers typically produce undesirable impurities that reduce the value of the reformate product. For instance, in a conventional steam reforming process, a hydrocarbon feed, such as methane, natural gas, propane, gasoline, naphtha, or diesel, is vaporized, mixed with steam, and passed over a steam reformiii-g catalyst. The majority of the feed hydrocarbon is converted to a mixture of hydxogen and impurities such as carbon monoxide and carbon dioxide. The reformed product gas is typically fed to a water-gas shift bed in which the carbon monoxide is cataLytically reacted with steam to form carbon dioxide and hydrogen. After the shift step, .additional purification step(s) are required to bring the hydrogen purity to acceptable levels. These steps can include, but are not limited to, methanation, selective oxidation reactions, passing the product stream through membrane separatoxs, and/or various adsorption processes. While such purification technologies may be known, the added cost and complexity of integrating them with a fuel reformer to produce a sufficiently pure hydrogen reformate can render their construction and operation impractical. In terms of power generation, fuel cells typically employ taydrogen as fuel and oxygen as an oxidizing agent in catalytic oxidation-reduction reactions to produce electricity. As with most industrial applications utilizing hydro ge-n, the purity of the hydrogen used in fuel cell systems is critical. Specifically, because power generation in fuel cells is proportional to the consumption rate of the reactants both their efficiencies and costs can be improved through the use of a highly pure hydrogen reformate. Moreover, the catalysts employed in many types of fu-el cells can be deactivated or permanently impaired by exposure to certain impu-rities. For use in a PEM fuel cell, hydrogen reformate should contain very low levels of carbon monoxide (<50 ppm) so as to prevent carbon monoxide poisoning of the catalysts. In the case of alkaline fuel cells, hydrogen reformate should contain low levels of carbon dioxide so as to prevent the formation of carbonate salts on the electrodes. As a result, an improved yet simplified reforming process capable of providing a high purity hydrogen reformate that is low in carbon oxides is greatly desired. This patent document relates to the following patent applications, commonly assigned to the same assignee hereof: U.S.S.N. 10/827,189, filed -April 19, 2004, entitled REFORMING WITH HYDRATION OF CARBON DIO-XIDE FIXING MATERIAL; U.S.S.N. 10/827,600, filed April 19, 2004, entitled- REACTOR WITH CARBON DIOXIDE FIXING MATERIAL; U.S.S.N. 10/827,148, filed April 19, 2004, entitled METHOD AND APPARATUS FOR PROVIDING A CONTINUOUS STREAM OF REFORMATE; U.S.S.N. 10/827,187, filed April 19, 2004, entitled APPARATUS AND METHOD FOR HYDROGEN GENERATION; and U.S.S.N. 10/827,580, filed April 19, 2004, entitled REACTOR AND APPARATUS FOR HYDROGEN GENERATION.

SUMMARY OF THE INVENTION In one aspect of the instant invention, an apparatus for generating hydrogen is provided. The apparatus comprises a catalyst bed comprising a reforming catalyst and a carbon dioxide fixing material that is capable of fixing carbon dioxide at a reforming reaction temperature and releasing fixed carbon dioxide at a regeneration temperature. A reactant heater that is capable of heating a reforming reactant to a reforming reaction temperature is in communication with the catalyst bed. A regeneration heater comprising a heat transfer device is also in communication with the catalyst bed for heating the catalyst bed to a regeneration temperature. The regeneration heater also includes a heat exchange device for one or more of heating the reactant heater, pre-heating a refonning reactant for delivery to the reactant heater, pre-heating an oxidant for delivery to the reactant heater, pre-heating an oxidant for delivery to the regeneration heater, and heating a reforming reactant to a reforming reaction temperature for delivery to the catalyst bed. The apparatus can optionally include a second catalyst bed comprising a refonning catalyst that is in communication with the reactant and regeneration heaters. The second catalyst bed can include a carbon dioxide fixing material that is capable of fixing carbon dioxide at a reforming reaction temperature and releasing fixed carbon dioxide at a regeneration temperature. The regeneration heater can comprise a heat transfer device for heating the second catalyst bed to the regeneration temperature. In addition, the regeneration heater can have a heat exchange device in fluid communication with the second catalyst bed for heating a reforming reactant to a reforming reaction temperature. another aspect of the instant invention, an apparatus for generating hydrogen is provided. The apparatus includes a first catalyst bed comprising a reforming catalyst and a carbon dioxide fixing material that is capable of fixing carbon dioxide at a reforming reaction temperature and releasing fixed carbon dioxide at a regeneration temperature. The catalyst bed is capable of promoting an oxidation reaction to produce regeneration heat for heating the catalyst bed to the regeneration temperature and has a heat transfer device for transferring a portion of the regeneration heat out of the first catalyst bed for use in heating a reactant heater, preheating a reforming reactant for delivery to the reactant heater, pre-heating an oxidant for delivery to the reactant heater, and heating a reforming reactant to a reforming reaction temperature. The apparatus further includes a reactant heater in communication with the catalyst bed that is capable of heating a reforming reactant to a reforming reaction temperature. The apparatus can optionally include a second catalyst bed comprising a reforming catalyst that is in communication with the reactant heater. The second catalyst bed can include a carbon dioxide fixing material that is capable of fixing carbon dioxide at a reforming reaction temperature and releasing fixed carbon dioxide at a regeneration temperature. The second catalyst bed can be capable of promoting an oxidation reaction to produce regeneration heat for heating the second catalyst bed to the regeneration temperature. The second catalyst bed can further comprise a heat transfer device for transferring a portion of the regeneration heat for one or more of heating the reactant heater, pre-heating a reforming reactant for delivery to the reactant heater, pre-heating an oxidant for delivery to the reactant heater, and heating a reforming reactant to a reforming reaction temperature for delivery to the first catalyst bed. In a process aspect of the instant invention a method for producing hydrogen is provided. The method includes the steps of heating a reforming reactant to a reforming reaction temperature with heat produced within a reactant heater and reforming the heated refonning reactant in a first catalyst bed having a reforming catalyst and a carbon dioxide fixing material to produce a reformate comprising hydrogen and carbon dioxide. The carbon dioxide fixing material in the first catalyst bed fixes at least a portion of the carbon dioxide to produce fixed carbon dioxide within the first catalyst bed and a carbon dioxide-depleted reformate. Regeneration heat is produced for heating a catalyst bed to a regeneration temperature. The reforming of the heated refonning reactant in the first catalyst bed is interrupted and the first catalyst bed is heated to the regeneration temperature with regeneration heat to release fixed carbon dioxide from the first catalyst bed. A portion of the regeneration heat is utilized for one or more of heating the reactant heater, pre-heating a reforming reactant for delivery to the reactant heater, pre-heating an oxidant for delivery to the reactant heater, pre-heating an oxidant for delivery to a regeneration heater, and heating a refonning reactant to a reforming reaction temperature for delivery to a catalyst bed. The regeneration heat can be produced by a combustion reaction within a regeneration heater or by an oxidation reaction within the first catalyst bed. When the first catalyst bed is heated to a regeneration temperature, the method can also include the step of refonning the heated reforming reactant in a second catalyst bed that has a reforming catalyst and a carbon dioxide fixing material to produce a reformate comprising hydrogen and carbon dioxide. The carbon dioxide fixing material in the second catalyst bed fixes at least a portion of the carbon dioxide to produce fixed carbon dioxide within the second catalyst bed and a carbon dioxide- depleted reformate. The reforming of the heated reforming reactant in the second catalyst bed can be interrupted and the second catalyst bed heated to the regeneration temperature with regeneration heat to release the fixed carbon dioxide from the second catalyst bed. The regeneration heat for heating the second catalyst bed can be produced by a combustion reaction in a regeneration heater or by an oxidation reaction within the second catalyst bed. A portion of the regeneration heat produced by an oxidation reaction within the second catalyst bed can be utilized to heat a reforming reactant to a reforming reaction temperature for delivery to the first catalyst bed. BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be understood by reference to the following description taken in conjunction with the accompanying drawings. Figure 1 is a schematic of an apparatus of the present invention. Figure 2 is a schematic of an apparatus of the present invention. Figure 3 is a schematic of an apparatus of the present invention. Figure 4 is a schematic of an apparatus of the present invention. While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual embodiment are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business- related constraints, which will vary from one implementation to another. Moreover it will be appreciated that such a development effort might be complex and time- consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. The present invention is directed to an apparatus and method for generating hydrogen from hydrocarbon-based fuels. The invention simplifies the production of a highly pure hydrogen-rich reformate by incorporating a carbon dioxide fixing mechanism into the initial hydrocarbon conversion reaction. The mechanism utilizes a carbon dioxide fixing material within the reforming catalyst bed that is capable of reacting with carbon dioxide and/or retaining carbon dioxide within the range of temperatures that is typical of such conversion reactions. The removal of carbon dioxide from the conversion product shifts the reaction equilibrium toward the production of higher concentrations of hydrogen and lower concentrations of carbon oxides. The carbon dioxide fixing materials used in such absorption-enhanced conversions can typically be caused to desorb or evolve carbon dioxide by application _. of a change in temperature, pressure, or a combination of changes in temperature and pressure. In an apparatus and method of the instant invention, the desorption of carbon dioxide comprises heating the catalyst bed and the carbon dioxide fixing material therein to a calcination or regeneration temperature. While both the reforming and regeneration reactions are endothermic in nature, the regeneration reaction typically requires higher temperatures and thus greater heat input. Because of the heating requirements for regeneration, the present invention utilizes separate heat sources for heating the reforming reactant(s) to a reforming reaction temperature and for heating the catalyst bed to a regeneration temperature. Moreover, it has been found that the thermal efficiency of the apparatus and method can be improved by integrating these heat sources so that heat generated for use in regenerating a catalyst bed can also be used to support the reforming reaction as well. In one embodiment, an apparatus of the present invention includes a catalyst bed comprising a reforming catalyst and a carbon dioxide fixing material that is capable of fixing carbon dioxide at a reforming reaction temperature and releasing fixed carbon dioxide at a regeneration temperature. A reactant heater is included that is in fluid communication with the catalyst bed for heating a reforming reactant to a reforming reaction temperature. A regeneration heater that has a heat transfer device in communication with the catalyst bed is included that is capable of heating the catalyst bed to a regeneration temperature. The regeneration heater also has a heat exchange device for one or more of transferring regeneration heat to the reactant heater, for pre-heating a reforming reactant for delivery to the reactant heater, for preheating an oxidant for delivery to the reactant heater, for pre-heating an oxidant for delivery to the regeneration heater, and for heating a reforming reactant to a reforming reaction temperature for delivery to the catalyst bed. In another embodiment, the catalyst bed is capable of promoting an oxidation reaction that provides regeneration heat to the catalyst bed and which eliminates the need for a separate regeneration heater. As noted herein, the apparatus and method of the instant invention concern the generation of a hydrogen-rich refonnate from a hydrocarbon-based fuel using multiple reactions within a common catalyst bed. Typical reactions that may be performed within the catalyst bed include fuel reforming reactions such as steam and/or autothermal reforming reactions that generate a reformate containing hydrogen, carbon oxides and potentially other impurities, water gas shift reactions wherein water and carbon monoxide are converted to hydrogen and carbon dioxide, and carbonation reactions wherein carbon dioxide is physically absorbed or chemically converted to a non-gaseous species such as a carbonate. Chemical equations for such a combination of reactions using methane as the hydrocarbon fuel and calcium oxide as the carbon dioxide fixing material are as follows:

CH4 + H₂0 → 3H₂ + CO (Steam Refonning) (I)

H₂O + CO → H₂ + CO₂ (Water Gas Shift) (II)

CO₂+ CaO → CaCO₃ (Carbonation) (III)

CH₄ + 2H₂O + CaO → 4H₂+ CaCO₃ (Combined) (IV)

While these equations exemplify the conversion of methane to a hydrogen-rich reformate, the scope of the invention should not be so limited. As used herein the term "hydrocarbon fuel" includes organic compounds having C--H bonds which are capable of producing hydrogen from a partial oxidation, autothennal and/or a steam reforming reaction. The presence of atoms other than carbon and hydrogen in the molecular structure of the compound is not excluded. Thus, suitable fuels for use in the method and apparatus disclosed herein can include, but are not limited to, hydrocarbon fuels such as natural gas, methane, ethane, propane, butane, naphtha, gasoline, and diesel fuel, and alcohols such as methanol, ethanol, propanol, and the like. Preferably, the hydrocarbon fuel will be a gas at 30°C, standard pressure. More preferably the hydrocarbon fuel will comprise a component selected from the group consisting of methane, ethane, propane, butane, and mixtures of the same. hi addition to a hydrocarbon fuel, a source of water will also be operably connected to the catalyst bed(s). Water can be introduced to the catalyst bed as a liquid or vapor, but is preferably steam. The ratios of the reaction feed components are determined by the desired operating conditions as they affect both operating temperature and hydrogen yield. In embodiments where the reforming reaction utilizes a steam reforming catalyst, the steam to carbon ratio is in the range between about 8:1 to about 1:1, preferably between about 5:1 to about 1.5:1 and more preferably between about 4:1 to about 2:1. However, when the catalyst bed is not being used to perform the reforming reaction, such as when the carbon dioxide fixing material is being heated to a calcination or regeneration temperature, the flow of steam to the bed will be reduced and in some embodiments may be interrupted, hi addition, it should also be noted that steam will be used at different temperatures depending on its intended function. For example, steam that is used for hydrating a carbon dioxide fixing material will typically be at a lower temperature than steam used for reforming the hydrocarbon fuel or regenerating the carbon dioxide fixing material. The refonning catalyst(s) may be in any form including pellets, spheres, extrudates, monoliths, as well as common particulates and agglomerates. Conventional steam reforming catalysts are well known in the art and can include nickel with amounts of cobalt or a noble metal such as platinum, palladium, rhodium, ruthenium, and/or iridium. The catalyst can be supported, for example, on magnesia, alumina, silica, zirconia, or magnesium aluminate, singly or in combination. Alternatively, the steam reforming catalyst can include nickel, preferably supported on magnesia, alumina, silica, zirconia, or magnesium aluminate, singly or in combination, promoted by an alkali metal such as potassium. Where the reforming reaction is preferably a steam refonning reaction, the reforming catalyst preferably comprises rhodium on an alumina support. Suitable reforming catalysts are commercially available from companies such as Cabot Superior Micropowders LLC (Albuquerque, NM) and Engelhard Corporation (Iselin, NJ). Certain refonning catalysts have been found to exhibit activity for both a reforming and water gas shift reaction. In particular, a rhodium catalyst on alumina support has activity for both a steam methane reforming reaction and a water gas shift reaction under the conditions present in the catalyst bed. Where the selected reforming catalyst does not catalyze the shift reaction, a separate water gas shift catalyst is an optional but highly prefened component of the catalyst bed. Reaction temperatures of an autothermal reforming reaction can range from about 550°C to about 900°C depending on the feed conditions and the catalyst, h a prefened embodiment, the reforming reaction is a steam reforming reaction with a reforming reaction temperature in the range from about 400°C to about 800°C, preferably in the range from about 450°C to about 700°C, and more preferably in the range from about 500°C to about 650°C. Prior to and during the reforming reaction the reforming reactants, and optionally the catalyst bed, are heated to a reforming reaction temperature. A reactant heater, as described herein, is provided for heating one or more of the reforming reactants for delivery to the catalyst bed(s). Where the catalyst bed was recently heated to a regeneration temperature, residual heat remaining in the catalyst bed is typically sufficient to sustain the reforming reaction without additional heat input to the catalyst bed. A water gas shift catalyst can optionally be disposed within the catalyst bed to convert steam and carbon monoxide to hydrogen and carbon dioxide. As noted above, providing a water gas shift reaction within the catalyst bed can be beneficial because carbon monoxide, in addition to being highly toxic to humans, is a poison to many fuel cell catalysts. The maximum level of carbon monoxide in the hydrogen- rich reformate should be a level that can be tolerated by fuel cells, typically below about 50 ppm. In addition, there is growing demand for higher purity reformate streams that have carbon monoxide concentrations below about 25 ppm, preferably below about 10 ppm, and more preferably below about 5 ppm. Water gas shift reactions generally occur at temperatures of from about 150°C to about 600°C depending on the catalyst used. Low temperature shift catalysts operate at a range of from about 150°C to about 300°C and include for example, copper oxide, or copper supported on other transition metal oxides such as zirconia, zinc supported on transition metal oxides or refractory supports such as silica, alumina, zirconia, etc., or a noble metal such as platinum, rhenium, palladium, rhodium or gold on a suitable support such as silica, alumina, zirconia, and the like. Higher temperature shift catalysts are preferably operated at temperatures ranging from about 300°C to about 600°C and can include transition metal oxides such as ferric oxide or chromic oxide, and optionally include a promoter such as copper or iron suicide. Suitable high temperature shift catalysts also include supported noble metals such as supported platinum, palladium and/or other platinum group members. Suitable water gas shift catalysts are commercially available from companies such as Cabot Superior Micropowders LLC (Albuquerque, NM) and Engelhard Corporation (Iselin, NJ). An apparatus of the present invention produces an improved reformate composition because a carbon dioxide fixing material is used to reversibly react with or "fix" carbon dioxide, thereby removing it from the reformate product and shifting the reforming reaction equilibrium toward the production of increased concentrations of hydrogen. Thus, an apparatus of the present invention comprises at least one catalyst bed that includes a carbon dioxide fixing material. As used in this disclosure, "carbon dioxide fixing material" is intended to refer to those materials that will adsorb or absorb carbon dioxide as well as materials that will convert carbon dioxide to a chemical species that is more easily removed from the reformate gas stream at a desired reforming reaction temperature. In addition, suitable fixing materials must be stable in the presence of steam, capable of maintaining high fixing capacity over multiple reforming/regeneration cycles, have low toxicity and pyrophoricity, and are preferably low in cost. Suitable carbon dioxide fixing materials can comprise alkaline earth oxide(s), doped alkaline earth oxide(s) or mixtures thereof. Preferably, the carbon dioxide fixing material will comprise calcium, strontium, or magnesium salts combined with binding materials such as silicates or clays that prevent the carbon dioxide fixing material from becoming entrained in the gas stream and that reduce crystallization which could decrease surface area and carbon dioxide absorption. Salts used to malce the initial bed can be any salt, such as an oxide or hydroxide that will convert to the carbonate under process conditions. Specific substances that are capable of fixing carbon dioxide at suitable reforming reaction temperatures include, but are not limited to, calcium oxide (CaO), calcium hydroxide (Ca(OH)₂), strontium oxide (SrO), strontium hydroxide (Sr(OH)₂) and mixtures thereof. Although not to be construed as limiting of suitable fixing materials, a prefened carbon dioxide fixing material is calcium oxide which reacts with carbon dioxide to produce calcium carbonate as shown in Equation III above. Other suitable carbon dioxide fixing materials that are described in the literature can be found in U.S. Patent No. 3,627,478, issued Dec. 14, 1971 to Tepper (describing weak base ion exchange resins at high pressure to absorb CO ); U.S. Patent No. 6,103,143, issued Aug. 15, 2000 to Sircar et al. (describing modified double layered hydroxides represented by the formula [Mg₍i-_X) Al_x(OH)₂] [CO₃]χ/_2yffiO.zM'₂CO₃ where 0.09<x<0.40, 0<y<3.5, 0<z<3.5 and M'=Na or K, and spinels and modified spinels represented by the formula Mg[Al₂]O₄.yK₂CO₃ where 0<y<3.5); U.S. Patent No. 6,692,545, issued Feb. 17, 2004 to Gittleman et al. (describing metal and mixed metal oxides of magnesium, calcium, manganese, and lanthanum and the clay minerals such as dolomite and sepiolite); and U.S. Patent Application Publication No. 2003/0150163 Al, published Aug. 14, 2003 by Murata et al. (describing lithium-based compounds such as lithium zirconate, lithium ferrite, lithium silicate, and composites of such lithium compounds with alkaline metal carbonates and/or alkaline earth metal carbonates); the disclosures of each of which are incorporated herein by reference, h addition, mineral compounds such as allanite, andralite, ankerite, anorthite, aragoniter, calcite, dolomite, clinozoisite, huntite, hydrotalcite, lawsonite, meionite, strontianite, vaterite, jutnohorite, minrecordite, benstonite, olekminskite, nyerereite, natrofairchildite, farichildite, zemkorite, butschlite, shrtite, remondite, petersenite, calcioburbankite, burbankite, khanneshite, carboncemaite, brinkite, pryrauite, strontio dressenite, and similar such compounds and mixtures thereof, can be suitable materials for fixing carbon dioxide. One or more of the described carbon dioxide fixing materials may be prefened depending on such variables as the hydrocarbon fuel to be reformed, the other catalysts in the catalyst bed, the selected reforming reaction conditions, and the nature and condition of the hydrogen-rich gas required to be produced, hi addition, the fixing material selected should exhibit low equilibrium partial pressure of carbon dioxide in the temperature range of about 400°C to about 650°C and high equilibrium partial pressure of carbon dioxide at temperatures from about 150°C to about 400°C above the selected reforming reaction temperature. The carbon dioxide fixing material may take any of the forms suggested above for catalysts, including pellets, spheres, extrudates, monoliths, as well as common particulates and agglomerates. In addition, the catalyst(s) and carbon dioxide fixing material may be combined into a composite mixture in one or more of the forms suggested above, hi a prefened embodiment, the carbon dioxide fixing material will be combined with catalyst(s) to form a mixture that is processed into a particulate composite using an aerosol method such as that disclosed in U.S. Patent No. 6,685,762, issued Feb. 3, 2004 to Brewster et al., the contents of which are incorporated herein by reference. As noted above, the carbon dioxide fixing material is a material that reversibly fixes carbon dioxide. Although not to be construed as limiting of suitable carbon dioxide fixing materials, a prefened regeneration reaction has the equation: CaCO₃ → CO₂+ CaO (regeneration) (V).

Testing has shown that the carbon dioxide fixing material will release fixed carbon dioxide when heated to a high temperature. The terms "calcine" and "regenerate" and their derivatives are intended to refer to those reactions or processes that comprise heating the catalyst bed to a temperature at which fixed carbon dioxide is released due to thennal decomposition, phase transition or some other physical or chemical mechanism. A temperature or range of temperatures at which fixed carbon dioxide is released is refened to herein as a "regeneration temperature". Moreover, heat that is generated for heating a catalyst bed to a regeneration temperature is refened to as "regeneration heat", hi a prefened embodiment, the regeneration temperature for the carbon dioxide fixing material will be above the selected reforming reaction temperature. More specifically, the regeneration temperature of the fixing material will be above about 550°C, preferably above about 625°C, and more preferably above about 700°C. Although conventional catalyst beds having multiple components tend to have a uniform distribution of components along the reactant pathway through the bed, it has been found that superior conversion rates can be achieved in an apparatus where the catalyst(s) and carbon dioxide fixing material(s) have a non-uniform distribution within the bed. Generally, the catalyst composition nearest the bed inlet should contain an amount of reforming catalyst that is greater than the average level of reforming catalyst across the bed. h contrast, the bed composition nearest the bed outlet should contain an amount of reforming catalyst that is less than the average level of reforming catalyst across the bed. h a prefened embodiment, no reforming catalyst is present proximate the bed outlet. A more detailed description of a catalyst bed having a non-uniform distribution of bed components may be found in U.S.S.N. 10/827,600, filed April 19, 2004 by Stevens et al., the contents of which are incorporated herein by reference. Reactor vessel(s) for housing a catalyst bed and other process equipment suitable for use in the apparatus and methods of the instant invention may be fabricated from any material capable of withstanding the operating conditions and chemical environment of the reactions described, and can include, for example, carbon steel, stainless steel, conel, Incoloy, Hastelloy, and the like. The operating pressure for the catalyst bed is preferably from about 0 to about 100 psig so that the system can operate using a low pressure hydrocarbon feed and with minimal compression. Ultimately, the operating pressure within the catalyst bed could depend on the delivery pressure required of the hydrogen to be produced and/or the pressure requirements of any intermediate purification or storage. Where the hydrogen is to be delivered to a fuel cell operating in the 1 to 20 kW range, an operating pressure of about 0 to about 100 psig is generally sufficient. As described herein, the operating temperatures within the reactor vessel will vary depending on the type reforming reaction, the type of reforming catalyst, the carbon dioxide fixing material, the type of water gas shift catalyst when used, and selected pressure conditions amongst other variables. In one embodiment, an apparatus of the present invention will comprise a plurality of two or more catalyst beds. Where a second catalyst bed is present, the bed comprises a reforming catalyst and is in fluid communication with a reactant heater for receiving a flow of reforming reactant at a reforming reaction temperature. Preferably, the second catalyst bed will comprise a carbon dioxide fixing material that is capable of fixing carbon dioxide at the refonning reaction temperature and releasing fixed carbon dioxide at a regeneration temperature. In such an embodiment, it is prefened that a regeneration heater used to heat the first catalyst bed to a regeneration temperature comprises a heat transfer device in thermal communication with the second catalyst bed that is capable of heating the second catalyst bed to a regeneration temperature. Such a regeneration heater can comprise separate heat transfer devices for transferring regeneration heat to multiple catalyst beds or may have a single heat transfer device that is integrated with each of the catalyst beds for selectively heating one or more of the catalyst beds to a regeneration temperature. An apparatus of the present invention includes a reactant heater for heating a refonning reactant to a reforming reaction temperature. The reactant heater is selected, sized and configured with the other components of the apparatus so as to be capable of delivering a reforming reactant at a desired reforming reaction temperature to the catalyst bed. The reactant heater can comprise one or more of an electrical heating element, a burner, furnace, combustor, or oxidizer for generating heat internally within the heater. Preferably, the reactant heater includes a combustion section wherein a reaction of a combustion fuel such as natural gas and an oxidant such as air produces heat within the reactant heater. An oxidation catalyst may optionally be used to promote the combustion reaction. A heat exchange device is provided within the reactant heater for heating the reforming reactant. The heat exchange device is selected, sized and located within the reactant heater for heating the reforming reactant to the desired refonning reaction temperature. The heat exchange device can comprise coiled tubing or other heat exchange elements known in the art for use in heating fluids. Multiple heat exchange devices can be used depending on the number of reforming reactants, the heating requirements of those reactants and the desired reforming reaction temperature to which the reactants are to be heated. For instance, where steam is to be generated and heated within the reactant heater, two or more heat exchange devices may be connected in series within the heater to achieve a flow of steam at the desired reaction temperature, h addition, where the reactant heater generates heat internally via an oxidation reaction, an optional heat exchange device can be located within the reactant heater for pre-heating oxidant for delivery to the site of the reaction. The reactant heater, and preferably a heat exchange device within the reactant heater, is in fluid communication with a reactant source for receiving a flow of reactant therefrom. The reforming reactant can comprise one or more of a reforming fuel, water, steam and an oxidant. Where the reforming reaction comprises a steam methane reforming reaction, a flow of steam can be generated within the reactant heater itself or can be generated in a process boiler or other device for delivery to the reactant heater for further heating to a reforming reaction temperature. In such an embodiment, natural gas or other methane-containing gas can also be heated to a reforming reaction temperature within the reactant heater. The reactant heater, and preferably a heat exchange device within the reactant heater, is in fluid communication with the catalyst bed for delivering a heated reforming reactant to the catalyst bed. An apparatus of the instant invention will further include means for producing a high temperature regeneration heat for use in heating the catalyst bed to a regeneration temperature. Regeneration heat can be produce within a dedicated regeneration heater for transfer to the catalyst bed or can be produced within the catalyst bed itself by an exothermic reaction, e.g., an oxidation reaction. h some embodiments, an apparatus of the present invention will include a regeneration heater for producing regeneration heat. Suitable regeneration heaters can comprise a furnace, burner, combustor, or oxidizer. Heat produced within a regeneration heater is delivered to the catalyst bed via a heat transfer device operably coupled to the regeneration heater. Heat transfer devices can comprise one or more of a coil, fin, heat pipe, or other thermal transfer device known in the art for transferring or conducting substantial quantities of heat to the bed or for conducting a heat transfer fluid to the bed. For instance, sufficient regeneration heat can be delivered to the catalyst bed by directing superheated gas(es) through the bed under conditions at which fixed carbon dioxide is released. Such gases can include heated streams of helium, nitrogen, steam and mixtures of the same, as well as heated exhaust gases from a fuel cell or the tail gas of a metal hydride-based hydrogen storage system. The regeneration heater and heat transfer device are selected and configured so as to be capable of heating the catalyst bed to a desired regeneration temperature. A regeneration heater preferably includes a combustion section for combusting a combustion fuel such as natural gas, and an oxidant such as combustion air to produce regeneration heat. The heat transfer device preferably comprises a heat pipe that is partially disposed within both the regeneration heater and the catalyst bed so as to provide thermal communication between the heater and bed. In an embodiment having a plurality of catalyst beds, the heat transfer device can comprise multiple heat pipes or a heat pipe wherein the fluid communication between an evaporative section and two or more condensation sections can be selectively controlled, hi an alternate embodiment, regeneration heat can be delivered to one or more of a plurality of catalyst beds via coiled tubing and by controlling the flow of a heat transfer fluid therethrough. In another embodiment, regeneration heat can be produced by an oxidation reaction within the catalyst bed itself, hi such an embodiment, the catalyst bed is capable of promoting an oxidation reaction to produce sufficient regeneration heat for heating the catalyst bed to a regeneration temperature. The reaction of a hydrocarbon fuel and oxidant can be promoted by a separate oxidation catalyst and/or a reforming catalyst having oxidative activity. Where regeneration heat is produced internally within the catalyst bed, the bed further comprises a heat exchange device for utilizing a portion of the regeneration heat for one or more of heating a reactant heater, preheating a reforming reactant for delivery to the reactant heater, pre-heating an oxidant for delivery to a reactant heater, and heating a reforming reactant to a reforming reaction temperature for delivery to a catalyst bed. Moreover, where such an apparatus comprises two or more catalyst beds, it is prefened that at least one of the catalyst beds include a heat exchange device for heating a reforming reactant to a reforming reaction temperature for delivery to the other catalyst bed. It has been found that the efficiency of the apparatus can be improved by recovering a portion of the regeneration heat for uses other than heating a catalyst bed to a regeneration temperature. Specifically, a regeneration heater can comprise one or more heat exchange devices for transferring heat to a reactant heater, pre-heating a reforming reactant such as natural gas and/or steam for delivery to a reactant heater, pre-heating an oxidant such as combustion air for delivery to a reactant heater, preheating an oxidant such as combustion air for delivery to a regeneration heater, and/or heating a reforming reactant such as natural gas and/or an oxidant to a reforming reaction temperature for delivery to a catalyst bed. In a prefened embodiment, the regeneration heater includes a plurality of heat exchange devices for heating various fluids with regeneration heat. By way of example, the heater can include a heat exchange device in fluid communication with the combustion section of the regeneration heater for delivering a pre-heated oxidant, another in fluid communication with the catalyst bed for heating a reforming reactant to a reforming reaction temperature, and yet another in fluid communication with the reactant heater for generating low temperature steam. Regardless of the means by which the carbon dioxide fixing materials is heated to a regeneration temperature, a volume of steam and/or nitrogen can optionally be passed through the bed as a sweep stream for removing desorbed carbon dioxide from the bed. It has also been found that hydrating a calcinated carbon dioxide fixing material tends to at least partially restore and sustain the fixing capacity of the carbon dioxide fixing material for one or more subsequent reforming/regeneration cycles. Such hydration can be achieved by contacting a calcinated carbon dioxide fixing material with water, preferably in the form of steam at a hydration temperature that is below the regeneration temperature, and more preferably, below the reforming reaction temperature. Specifically, the hydration temperature should be less than 600°C, preferably below about 500°C, more preferably below about 400°C and even more preferably below about 300°C. For instance, sufficient hydration can be achieved by passing steam at about 200°C through the catalyst bed. The amount of steam that is needed to achieve effective hydration will vary depending on the volume of the catalyst bed, the surface area of the carbon dioxide fixing materials within the bed, the type of fixing material used, the structure or matrix of catalyst(s) and fixing materials within the bed and the flow rate of steam through the bed. Where the fixing material comprises calcium oxide, sufficient steam should be passed through the catalyst bed to convert at least about 10% of the calcium oxide to calcium hydroxide to achieve the desired effect. More specifically, at least about 0.03 kg of steam per kg of calcium oxide is needed to achieve sufficient hydration. Greater quantities of steam may be needed where refom ing feed flow rates are higher. Additional description concerning the hydration of carbon dioxide fixing materials may be had by reference to U.S.S.N. 10/827,189, filed April 19, 2004 by Stevens et al. In another embodiment, an apparatus of the present invention comprises two or more catalyst beds comprising first and second catalyst beds, each catalyst bed comprising a reforming catalyst and a carbon dioxide fixing material, the carbon dioxide fixing material capable of fixing carbon dioxide at a reforming reaction temperature and releasing fixed carbon dioxide at a regeneration temperature. In such an embodiment, one bed is operated in reforming mode while simultaneously the second bed is heated to a calcination or regeneration temperature. Thus, the apparatus further comprises one heat generating means for heating a catalyst bed or reforming reactant to a reforming reaction temperature and a second heat generating means for generating heat for heating a catalyst bed to a calcination or regeneration temperature. It is prefened that the two heat generating means, be thermally integrated so as to improve the thermal efficiency of the total system. Thennal integration is achieved by pre-heating reforming reactant feed(s) such as hydrocarbon fuel and steam with excess heat generated for heating the second catalyst bed to a calcination temperature. Where the heat generating means comprise a burner or combustor, oxidant(s) to be reacted in the heat generating means can likewise be pre-heated to improve the thermal efficiency of the overall reformer system. In another embodiment, a method for producing hydrogen is provided. The method includes the steps of heating a reforming reactant to a reforming reaction temperature with heat produced within a reactant heater and reforming the heated reforming reactant in a first catalyst bed having a reforming catalyst and a carbon dioxide fixing material to produce a reformate comprising hydrogen and carbon dioxide. The carbon dioxide fixing material in the first catalyst bed fixes at least a portion of the carbon dioxide to produce fixed carbon dioxide within the first catalyst bed and a carbon dioxide-depleted reformate. Regeneration heat is produced for heating the first catalyst bed to a regeneration temperature. The reforming of the heated reforming reactant in the first catalyst bed is interrupted and the first catalyst bed is heated to the regeneration temperature with regeneration heat to release fixed carbon dioxide from the first catalyst bed. A portion of the regeneration heat is utilized for one or more of heating the reactant heater, pre-heating a reforming reactant for delivery to the reactant heater, pre-heating an oxidant for delivery to the reactant heater, pre-heating an oxidant for delivery to a regeneration heater, and heating a reforming reactant to a reforming reaction temperature for delivery to a catalyst bed. The regeneration heat can be produced by a combustion reaction within a regeneration heater or by an oxidation reaction within the first catalyst bed. When the first catalyst bed is heated to a regeneration temperature, the method can also include the step of reforming the heated reforming reactant in a second catalyst bed that has a reforming catalyst and a carbon dioxide fixing material to produce a refonnate comprising hydrogen and carbon dioxide. The carbon dioxide fixing material in the second catalyst bed fixes at least a portion of the carbon dioxide to produce fixed carbon dioxide within the second catalyst bed and a carbon dioxide- depleted reformate. The reforming of the heated reforming reactant in the second catalyst bed can be interrupted and the second catalyst bed heated to the regeneration temperature with regeneration heat to release the fixed carbon dioxide from the second catalyst bed. The regeneration heat for heating the second catalyst bed can be produced by a combustion reaction in a regeneration heater or by an oxidation reaction within the second catalyst bed. A portion of the regeneration heat produced by an oxidation reaction within the second catalyst bed can be utilized to heat a reforming reactant to a reforming reaction temperature for delivery to the first catalyst bed. A detailed description of the catalyst bed(s), the reactant heater and the regeneration heater, their features and operation as utilized in a method of the present invention are provided herein and are not repeated here.

DETAILED DESCRIPTION OF THE FIGURES As illustrated in Figure 1, apparatus 100 has catalyst bed 130, reactant heater 120 and regeneration heater 110. Regeneration heater 110 has heat exchangers 111 and 113 for generating steam and pre-heating reforming fuel, respectively. Boiler feed water is directed to heat exchanger 11 1 tlirough line 102 and steam generated within the heater is directed to the reactant heater through line 112. Reactant heater 120 has heat exchanger 123 for heating the steam to a reforming reaction temperature, which can then be directed to the catalyst bed through line 122. Heat is generated within reactant heater 120 by a combustion reaction fueled by a combustion fuel and air (not shown). Heat exchanger 113 within the regeneration heater is sized and configured to heat the reforming fuel, e.g. natural gas, to a reforming reaction temperature for delivery directly to the catalyst bed 130 via line 114. Catalyst bed 130 includes a reforming catalyst (not shown) for converting the reforming fuel and steam to reformate comprising hydrogen and carbon dioxide. The reformate is directed out of the catalyst bed to a downstream process unit or storage via line 132. A carbon dioxide fixing material (not shown) is also present within catalyst bed 130 for fixing carbon dioxide during the reforming reaction to produce fixed carbon dioxide within the catalyst bed and a carbon dioxide-depleted reformate. Fixed carbon dioxide desorbs and is released from the catalyst bed by heating the bed to a regeneration temperature with heat produced within regeneration heater 110. Specifically, regeneration heater 110 has heat pipe 140 for transferring heat to catalyst bed 130. Heat pipe 140 is a conventional heat pipe having evaporative section 141 embedded within the regeneration heater and condensing section 142 embedded within the catalyst bed. Heat is generated within regeneration heater 110 by a combustion reaction that is fueled by combustion fuel 101 and combustion air 103. Hot combustion products generated by the combustion reaction transfer heat to evaporative section 141 and vaporize a fluid therein. The vaporized fluid flows to condensing section 142 where the condensing vaporized fluid gives up heat to the catalyst bed causing the fixed carbon dioxide to be released from the bed. Preferably, a reduced flow of steam or other inert gas is directed through the bed to facilitate the removal of desorbed carbon dioxide. The carbon dioxide can be directed out of bed 130 through line 132 or via another line. Following regeneration, residual heat remains within bed 130 that facilitates the resumption of the endothermic steam reforming reaction. As illustrated in Fig. 2, apparatus 200 comprises a plurality of catalyst beds 230 and 230', reactant heater 220 and regeneration heater 210. Regeneration heater 210 has heat exchangers 211 and 213 for generating steam and pre-heating reforming fuel, respectively. Boiler feed water is directed to heat exchanger 211 through line 202 and steam generated within the heater is directed to the reactant heater through line 212. Heat exchanger 223 receives and heats the steam to a reforming reaction temperature that can then be directed to the catalyst bed tlirough line 222. Heat is generated within reactant heater 220 by a combustion reaction fueled by combustion fuel 221 and combustion air 227. Within the regeneration heater, heat exchanger 213 receives and pre-heats a reforming fuel, in either liquid or gaseous form, from line 204. The pre-heated reforming fuel is directed to heat exchanger 225 where it is heated to a reforming reaction temperature. The steam and reforming fuel are mixed and directed to catalyst beds 230 and 230' via line 222 and flow control valve 250. Catalyst beds 230 and 230' include a reforming catalyst (not shown) that converts the reforming fuel and steam to a reformate comprising hydrogen and carbon dioxide. The refonnate is directed out of the catalyst beds to a downstream process unit or storage via lines 232 and 232', respectively. A carbon dioxide fixing material (not shown) that is present within the catalyst beds 230 and 230' fixes a portion of the carbon dioxide in the reformate to produce fixed carbon dioxide within the catalyst beds and a carbon dioxide-depleted reformate. The catalyst beds can then be heated to a regeneration temperature to desorb or release fixed carbon with heat generated within regeneration heater 210. Heat is generated within regeneration heater 210 by a combustion reaction that is fueled by combustion fuel 201 and combustion air 203. Regeneration heater 210 has heat transfer device 240 for transferring regeneration heat from the heater to one or more of the catalyst beds. Heat transfer device 240 has heat exchange element 241 within the regeneration heater and heat exchange elements 245 and 245' respectively within the catalyst beds. Lines 242 and 243 and flow control valves 246 and 247 control the flow of a heat transfer fluid to one or more of these heat exchange elements. In some embodiments, flow control valves 246, 247, and 250 will be actuated so that one of the catalyst beds receives a flow of a reforming reactant(s) tlirough valve 250 while the other bed receives regeneration heat from regeneration heater 210. hi this manner, the apparatus can continuously produce hydrogen in one catalyst bed while the other bed is heated to a regeneration temperature to release fixed carbon dioxide. It is also envisioned that flow control valves 246 and 247 may be actuated so that a portion of the regeneration heat is directed to a catalyst bed that is receiving a mixture of reforming reactants so as to provide additional heat directly to the reforming reaction. Further, a source of steam or other inert gas (not shown) in fluid communication with the catalyst beds can be provided for directing a sweep stream of gas through a bed during regeneration. The apparatus illustrated in Fig. 3 is very similar to that shown in Fig. 2, with the notable exception that combustion air 303 to be combusted within regeneration heater 310 is pre-heated within heat exchanger 317 prior to combustion. Similarly, combustion air 327 is pre-heated in heat exchanger 326 prior to its combustion in reactant heater 320. The pre-heating of combustion air 303 and 327 can substantially improve the thermal efficiency of the apparatus. As illustrated in Fig. 4, apparatus 400 includes reactant heater 420 and catalyst beds 430 and 430'. Catalyst beds 430 and 430' include several heat exchangers including exchangers 431 and 431' for heating natural gas to a reforming reaction temperature for delivery to one or more of the catalyst beds through flow control valve 480. Heat exchangers 435 and 435 ' generate steam from boiler feed water 402 for delivery to heat exchanger 425 within the reactant heater 420. Heat exchanger

425 heats the steam to a reforming reaction temperature for delivery to one or more of the catalyst beds through line 422 and flow control valve 440. Heat is generated within reactant heater 420 by a combustion reaction fueled by combustion fuel 421 and combustion air 427. Heat exchangers 433 and 433' are provided within the catalyst beds for directly transferring heat between the catalyst beds. The catalyst beds 430 and 430' each includes a reforming catalyst (not shown) for converting the natural gas and steam to a reformate comprising hydrogen and carbon dioxide. A carbon dioxide fixing material (not shown) is present within each of the catalyst beds for producing fixed carbon dioxide within the catalyst beds and a carbon dioxide-depleted reformate. The beds can be heated to a regeneration temperature to desorb or release the fixed carbon dioxide. The catalyst beds further include a catalyst that is capable of promoting an oxidation reaction within the catalyst bed. The heated products of this reaction provide regeneration heat to raise the temperature of the bed to a regeneration temperature at which the fixed carbon dioxide will be released from the catalyst beds. During operation, one of the catalyst beds is operated to produce hydrogen while the temperature of the other bed is raised to a regeneration temperature so as to release fixed carbon dioxide therefrom. Specifically, flow control valves 440, 450, 470 and 480 can be actuated and a flow of oxidant 409 initiated into catalyst bed 430 so that oxidation occurs to heat the bed to a regeneration temperature. Steam 402 is directed through heat exchanger 435 and then to reactant heater 420 via line 412 to raise the temperature of the steam to a refonning reaction temperature. Natural gas 404 is directed through heat exchanger 431 to heat the fuel to a reforming reaction temperature for delivery to the catalyst bed 430'. h this manner, reactants to be reformed in catalyst bed 430' are at least partially heated with the regeneration heat produced in catalyst bed 430. The oxidation reaction within bed 430 is controlled so that bed 430 does not heat to a temperature at which the catalysts, the carbon dioxide fixing material or other bed components are damaged or otherwise deactivated.

Subsequently, the oxidation reaction within bed 430 is discontinued by interrupting the flow of oxidant 409 to the bed. A portion of the regeneration heat produced in bed 430 remains within the bed as residual heat. Flow control valves 440, 450, 470 and 480 are actuated and a flow of oxidant 409' is initiated to bed 430' so that oxidation occurs to heat the bed to a regeneration temperature while heated natural gas and steam are pre-heated for reforming in bed 430. Should the endothennic reforming reaction cool a catalyst bed below a reforming reaction temperature, regeneration heat can be transfened directly from the bed undergoing regeneration to the refonning reaction bed. Heat exchange elements 433 and 433' are provided for directly transferring regeneration heat between beds 430 and 430' as needed. The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below.

Claims

WHAT IS CLAIMED IS:

1. An apparatus for generating hydrogen, the apparatus comprising: a catalyst bed comprising a reforming catalyst and a carbon dioxide fixing material, the carbon dioxide fixing material capable of fixing carbon dioxide at a reforming reaction temperature and releasing fixed carbon dioxide at a regeneration temperature; a reactant heater in communication with the catalyst bed, the reactant heater capable of heating a refonning reactant to a refonning reaction temperature; and a regeneration heater comprising a heat transfer device in communication with the catalyst bed capable of heating the catalyst bed to a regeneration temperature, and a heat exchange device for one or more of transferring heat to the reactant heater, pre-heating a reforming reactant for delivery to the reactant heater, pre-heating an oxidant for delivery to the reactant heater, pre-heating an oxidant for delivery to the regeneration heater, and heating a reforming reactant to a reforming reaction temperature for delivery to the catalyst bed.

2. The apparatus of claim 1, wherein the heat transfer device comprises one or more of a coil, fin and heat pipe.

3. The apparatus of claim 1, wherein the regeneration heater comprises a combustion section for combusting a combustion fuel and an oxidant, and further comprises a heat exchange device for pre-heating the oxidant for delivery to the combustion section.

4. The apparatus of claim 1, wherein the reactant heater comprises a heat exchange device for heating the reforming reactant to the reforming reaction temperature.

The apparatus of claim 1, wherein the reactant heater comprises a combustion section for combusting a combustion fuel and an oxidant, and further comprises a heat exchange device for pre-heating the oxidant for delivery to the combustion section.

6. The apparatus of claim 1, further comprising a second catalyst bed comprising a reforming catalyst, the second catalyst bed in communication with the reactant heater and the regeneration heater.

7. The apparatus of claim 6, wherein the second catalyst bed further comprises a carbon dioxide fixing material capable of fixing carbon dioxide at the reforming reaction temperature and releasing fixed carbon dioxide at a regeneration temperature.

8. The apparatus of claim 7, wherein the regeneration heater comprises a heat transfer device in communication with the second catalyst bed capable of heating the second catalyst bed to the regeneration temperature.

9. The apparatus of claim 8, wherein the regeneration heater comprises a heat exchange device in communication with the second catalyst bed capable of heating a reforming reactant to a reforming reaction temperature for delivery to the second catalyst bed.

10. An apparatus for generating hydrogen, the apparatus comprising: a first catalyst bed comprising a refonning catalyst and a carbon dioxide fixing material, the carbon dioxide fixing material capable of fixing carbon dioxide at a reforming reaction temperature and releasing fixed carbon dioxide at a regeneration temperature, wherein the first catalyst bed is capable of promoting an oxidation reaction to produce regeneration heat for heating the first catalyst bed to the regeneration temperature, the first catalyst bed further comprising a heat exchange device for utilizing a portion of the regeneration heat for one or more of heating a reactant heater, pre-heating a reforming reactant for delivery to the reactant heater, pre-heating an oxidant for delivery to a reactant heater, and heating a reforming reactant to a reforming reaction temperature for delivery to a second catalyst bed; and a reactant heater in communication with the first catalyst bed, the reactant heater capable of heating a reforming reactant to a reforming reaction temperature.

11. The apparatus of claim 10, further comprising a second catalyst bed comprising a reforming catalyst, the second catalyst bed in communication with the reactant heater.

12. The apparatus of claim 11, wherein the second catalyst bed further comprises a carbon dioxide fixing material capable of fixing carbon dioxide at the reforming reaction temperature and releasing fixed carbon dioxide at a regeneration temperature.

13. The apparatus of claim 12, wherein the second catalyst bed is capable of promoting an oxidation reaction to produce regeneration heat for heating the second catalyst bed to the regeneration temperature.

14. The apparatus of claim 13, wherein the second catalyst bed further comprises a heat exchange device for utilizing a portion of the regeneration heat for one or more of heating the reactant heater, pre-heating a refonning reactant for delivery to the reactant heater, pre-heating an oxidant for delivery to a reactant heater, and heating a reforming reactant to a reforming reaction temperature for delivery to the first catalyst bed.

15. A method for producing hydrogen, the method comprising the steps of: heating a reforming reactant to a reforming reaction temperature with heat produced within a reactant heater; reforming the heated reforming reactant in a first catalyst bed comprising a reforming catalyst and a carbon dioxide fixing material to produce a refonnate comprising hydrogen and carbon dioxide, the carbon dioxide fixing material fixing at least a portion of the carbon dioxide to produce fixed carbon dioxide within the first catalyst bed and a carbon dioxide- depleted reformate; producing regeneration heat for heating a catalyst bed to a regeneration temperature; interrupting the reforming of the heated reforming reactant in the first catalyst bed and heating the first catalyst bed to the regeneration temperature with regeneration heat to release fixed carbon dioxide from the first catalyst bed; and utilizing a portion of the regeneration heat for one or more of heating the reactant heater, pre-heating a reforming reactant for delivery to the reactant heater, pre-heating an oxidant for delivery to the reactant heater, pre-heating an oxidant for delivery to a regeneration heater, and heating a reforming reactant to a reforming reaction temperature for delivery to a catalyst bed.

16. The method of claim 15, wherein heat is produced within the reactant heater by a combustion reaction.

17. The method of claim 15, wherein the regeneration heat is produced by a combustion reaction within a regeneration heater.

18. The method of claim 15, wherein the regenerating heat is produced by an oxidation reaction within the first catalyst bed.

19. The method of claim 15, wherein the reforming reaction temperature is between about 400°C and about 800°C.

20. The method of claim 15, wherein the regeneration temperature is at least about 550°C.

21. The method of claim 15, wherein the reforming reactant comprises at least one of a fuel, water, steam, and an oxidant.

22. The method of claim 15, further comprising refonning the heated reforming reactant in a second catalyst bed comprising a reforming catalyst and a carbon dioxide fixing material to produce a reformate comprising hydrogen and carbon dioxide when the first catalyst bed is heated to a regeneration temperature, the carbon dioxide fixing material fixing at least a portion of the carbon dioxide to produce fixed carbon dioxide within the second catalyst bed and a carbon dioxide-depleted refonnate.

23. The method of claim 22, further comprising interrupting the reforming of the heated reforming reactant in the second catalyst bed and heating the second catalyst bed to the regeneration temperature with regeneration heat to release fixed carbon dioxide from the second catalyst bed.

24. The method of claim 23, wherein the regenerating heat is produced by an oxidation reaction within the second catalyst bed.

25. An apparatus for generating hydrogen, the apparatus comprising: two or more catalyst beds comprising first and second catalyst beds, each catalyst bed comprising a reforming catalyst and a carbon dioxide fixing material, the carbon dioxide fixing material capable of fixing carbon dioxide at a reforming reaction temperature and releasing fixed carbon dioxide at a regeneration temperature; one heat generating means for heating a catalyst bed to a reforming reaction temperature; a second heat generating means for generating heat for heating a catalyst bed to a calcination temperature; wherein a reforming reactant feed or an oxidant to be reacted in a heat generating means is pre-heated with excess heat generated by the second heat generating means.