Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J12/00—Chemical processes in general for reacting gaseous media with gaseous media; Apparatus specially adapted therefor
  • B01J12/007—Chemical processes in general for reacting gaseous media with gaseous media; Apparatus specially adapted therefor in the presence of catalytically active bodies, e.g. porous plates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/0006—Controlling or regulating processes
  • B01J19/002—Avoiding undesirable reactions or side-effects, e.g. avoiding explosions, or improving the yield by suppressing side-reactions
  • B01J19/0026—Avoiding carbon deposits
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/02—Apparatus characterised by being constructed of material selected for its chemically-resistant properties
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
  • C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
  • C01B3/32—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air
  • C01B3/34—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents
  • C01B3/48—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents followed by reaction of water vapour with carbon monoxide
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F19/00—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers
  • F28F19/02—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers by using coatings, e.g. vitreous or enamel coatings
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00049—Controlling or regulating processes
  • B01J2219/00245—Avoiding undesirable reactions or side-effects
  • B01J2219/00247—Fouling of the reactor or the process equipment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/02—Apparatus characterised by their chemically-resistant properties
  • B01J2219/0204—Apparatus characterised by their chemically-resistant properties comprising coatings on the surfaces in direct contact with the reactive components
  • B01J2219/0236—Metal based
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/02—Processes for making hydrogen or synthesis gas
  • C01B2203/0205—Processes for making hydrogen or synthesis gas containing a reforming step
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/02—Processes for making hydrogen or synthesis gas
  • C01B2203/0283—Processes for making hydrogen or synthesis gas containing a CO-shift step, i.e. a water gas shift step
  • C01B2203/0288—Processes for making hydrogen or synthesis gas containing a CO-shift step, i.e. a water gas shift step containing two CO-shift steps
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/08—Methods of heating or cooling
  • C01B2203/0872—Methods of cooling
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/10—Catalysts for performing the hydrogen forming reactions
  • C01B2203/1005—Arrangement or shape of catalyst
  • C01B2203/1035—Catalyst coated on equipment surfaces, e.g. reactor walls
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/10—Catalysts for performing the hydrogen forming reactions
  • C01B2203/1041—Composition of the catalyst
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/10—Catalysts for performing the hydrogen forming reactions
  • C01B2203/1041—Composition of the catalyst
  • C01B2203/1047—Group VIII metal catalysts
  • C01B2203/1064—Platinum group metal catalysts
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/10—Catalysts for performing the hydrogen forming reactions
  • C01B2203/1041—Composition of the catalyst
  • C01B2203/1082—Composition of support materials
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/10—Catalysts for performing the hydrogen forming reactions
  • C01B2203/1041—Composition of the catalyst
  • C01B2203/1094—Promotors or activators

Definitions

• the invention concerns a reformate stream cooler in which the surfaces of the cooler that come into contact with the reformate stream are coated with a catalytically active material.
• Gas generation systems comprising a reformer to generate a reformate stream, a reformate stream cooler, and a downstream shift stage to purify the reformate stream are used in fuel-cell-powered motor vehicles to provide the hydrogen that is needed to operate the fuel cells.
• the reforming of carbon-containing fuels produces by-products such as carbon monoxide, which must only be present in very small quantities in proton-exchange membrane (PEM) fuel cells. Accordingly gas purification upstream of the fuel cell is required.
• Present technology for the reduction of the carbon monoxide concentration in hydrogen-rich streams include the water-gas shift reaction and the selective oxidation of carbon monoxide in fixed-bed reactors with suitable selective oxidation catalysts.
• Metal dusting corrosion can be prevented by carrying out the desired process outside of the critical temperature range for metal dusting corrosion, or by "bypassing" the critical temperature range as rapidly as possible.
• a common method of bypassing the critical temperature range is quenching the reformate stream by introducing water into the reformate stream between the reformer and the shift stage. The disadvantage of this method is that the thermal energy contained in the reformate stream can not then be utilized elsewhere, which leads to a significantly lower efficiency.
• EP 0 974 393 A2 provides a gas generation system comprising a reformer, a carbon monoxide shift reactor, and a catalytic burner.
• the publication describes that the fuel gas is conducted in counter-current flow, which allows efficient cooling of the carbon monoxide shift stage (which shifts the shift gas balance in the reformate stream towards a lower carbon monoxide concentration), in a more compact design.
• the carbon monoxide shift stage which shifts the shift gas balance in the reformate stream towards a lower carbon monoxide concentration
• a gas generation system comprises a reformer to generate a hydrogen- containing reformate stream, a reformate stream cooler (or heat exchanger), and a shift stage downstream of the reformate cooler to purify the reformate stream.
• the surfaces of the cooler that come into contact with the reformate stream are coated with a material that contains at least one catalytically active constituent.
• the coating is selected such that it also protects against corrosion and sooting in the presence of oxidizing, reducing, and carbon-containing gases.
• Fig. 1 is a flow diagram for a conventional system for the reforming of carbon- containing fuels with subsequent gas purification and water injection.
• Fig. 2 is a flow diagram for an embodiment of the present system for the reforming of carbon-containing fuels with gas purification and reformate stream cooling.
• the carbon monoxide concentration in the reformate stream has to be reduced. Reducing the carbon monoxide concentration also suppresses or prevents the reaction that is responsible for formation and deposition of carbon black, which leads to carburization and consequently to the embrittlement of components.
• Components that are at risk include pipes and channels exposed to the carbon monoxide-containing reformate stream, heat exchangers used to cool the reformate stream, shift stages, nozzles, and all of the components connected downstream of the reformer, but upstream of the fuel cell.
• some of the catalyst material in these components may be clogged by soot particulates, rendering it unavailable for the catalytic reaction.
• Reactors in gas generation system are typically constructed of high-temperature- resistant alloys, which provide a long service life. But in a carbon monoxide- containing reformate stream atmosphere, iron and nickel, which are constituents of such alloys, exhibit significant catalytic activity with respect to sooting.
• Fig. 1 shows a conventional method of preventing metal dusting corrosion.
• the critical temperature is bypassed by quenching the reformate stream 4 by introducing water 5 into the reformate stream between a reformer 1 and a shift stage 3.
• This process has the disadvantage that thermal energy contained in the reformate stream cannot be used to heat other reactant streams.
• the present gas generation system which comprises a reformer 1 to generate a reformate stream 4, a reformate stream cooler 2, and a shift stage 3 connected downstream of cooler 2 for reformate stream purification, may be employed.
• the surfaces of cooler 2 that come into contact with the reformate stream 4 are coated with a soot-inhibiting material that is also catalytically active with respect to the water-gas shift reaction.
• the composition of the coating may vary along the flow path.
• the coating contains at least two areas of different composition in terms of soot-inhibiting activity and/or catalytic activity with respect to the water-gas shift reaction.
• cooler 2 comprises a feed line and a discharge line, connecting reformer 1 with cooler 2 and cooler 2 with the downstream shift stage 3, respectively.
• the lines are coated, with a composition that exhibits greater soot- inhibiting activity and lesser catalytic activity with respect to the water-gas shift reaction than the coating inside cooler 2.
• cooler 2 and the feed line and the discharge line are coated with a material of the same composition, and cooler 2 is coated with an additional material, selected to exhibit high catalytic activity with respect to the water-gas shift reaction and lower soot-inhibiting activity than the common coating.
• the oxygen- ion-conducting support material is thermally stabilized against surface losses by the addition of oxides such as Zr0 2 and/or Ce ⁇ 2 .
• oxides such as Zr0 2 and/or Ce ⁇ 2 .
• the addition of a cerium compound to the catalytic material leads to an increased activity of the catalytic material for promoting the water-gas shift reaction and acting as an. oxygen storage unit.
• Caesium compounds that may be used include caesium oxides or other oxygen-containing compounds that are converted to oxides at high temperatures, such as carbonate, acetate, and nitrate.
• Vanadium components that may be used in the production of the catalyst, individually or in the form of mixtures, include various vanadium oxides or vanadium compounds that are converted to vanadium oxides when heated in contact with air.
• Suitable vanadium oxides include V 2 0 5 , V3O7, V 4 0 9/ and V 6 0 ⁇ 3 , as V 2 0 4 , and oxides such as V 2 0 3 , V3O5, V4O7, V5O9, V 6 On, and V7O13, with V 2 0 5 being particularly preferred.
• Vanadium oxides of this type may be produced, for example, by the thermal decomposition of ammonium metavanadate (NH 4 VO3), by the heating of mixtures of V 2 0 3 and V 2 0 5 , or by the reduction of V 2 Oswith sulphur oxide gas.
• NH 4 VO3 ammonium metavanadate
• Suitable vanadium compounds that are converted to a vanadium oxide when heated in contact with air include ammonium metavanadate, vanadyl sulphate, vanadyl chloride, vanadyl dichloride dihydrate, vanadyl trichloride, other vanadyl halides, metavanadic acid, pyrovanadic acid, vanadium hydroxide, vanadyl acetylace- tonate, or vanadyl carboxylates, such as vanadyl oxalate, with ammonium metavanadate being particularly preferred.
• Oxides such as V 2 0 5 and Si0 2 , act as protective agents against aging of the noble-metal catalyst in the coating as they are structural promoters, which - on account of their thermally stabilizing action - inhibit structural changes of the noble- metal catalyst during manufacturing of the coating and during operation of the gas generation system.
• the noble-metal catalyst may comprise at least a metal, a metal- containing compound, and/or a metal-containing alloy.
• the catalytically active coating may be applied to cooler 2 using processes known in the art, such as dip-coating, spraying, doctor blade application, or other application processes.
• the coating may also make it possible to suppress methana- tion that takes place as an undesired secondary reaction.
• a water-gas shift reaction to reduce the carbon monoxide concentration takes place to some extent in cooler 2 prior to the actual shift stage 3. This results in some hydrogen production occurring in cooler 2 in addition to the hydrogen production which occurs in the reformer. This makes it possible to reduce the size of the subsequent shift stage(s), which in turn results in a more lightweight and compact gas generation system.
• the sen/ice life of the catalysts employed in the shift stages is increased.
• cooler 2 makes it possible to extract a significant amount of heat from the reformate stream 4.
• the reaction temperatures in cooler 2 are typically in the range of 300 to 850°C, preferably between 400 and 700°C.
• a reformate stream cooler coated in this manner is able to adjust the thermodynamic equilibrium with respect to the water-gas shift reaction suitable for the discharge conditions, such as temperature, pressure, stoichiometric ratios (water/carbon monoxide ratios), while at the same time preventing sooting.
• cooler 2 The surfaces of cooler 2 that come into contact with the reformate stream 4 may be coated with at least one layer of a further base coating.
• This base coating is disposed between the wall of the cooler and the coating layer and comprises at least one metal, typically chromium, silicon, aluminum, magnesium, manganese, titanium, rare earths, and/or compounds and/or alloys of these substances.
• the base coating or "diffusion coating" may be applied to cooler 2 in a manner known in the art.
• Various processes that are appropriate for corrosion- and wear-resistant high- temperature composite materials may be employed. Examples of possible processes include, but are not limited to, build-up welding, thermal spray processes, such as plasma spraying, vacuum plasma spraying, plasma-powder surfacing, highrvelocity flame spraying, or laser coating.
• the diffusion coating of the present system offers excellent corrosion protection as well as protection against sooting in oxidizing, reducing, and carbon- containing gases.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• General Health & Medical Sciences (AREA)
• Health & Medical Sciences (AREA)
• Inorganic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Hydrogen, Water And Hydrids (AREA)
• Fuel Cell (AREA)

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• 2001
  • 2001-08-31 DE DE10142794A patent/DE10142794A1/de not_active Withdrawn
• 2002
  • 2002-08-30 WO PCT/EP2002/009708 patent/WO2003020637A1/en not_active Application Discontinuation
  • 2002-08-30 US US10/487,579 patent/US20050074377A1/en not_active Abandoned

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