Classifications

• • 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
  • C01B3/22—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by decomposition of gaseous or liquid organic compounds
  • C01B3/24—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by decomposition of gaseous or liquid organic compounds of hydrocarbons
  • C01B3/26—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by decomposition of gaseous or liquid organic compounds of hydrocarbons using catalysts
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
  • D01F9/08—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
  • D01F9/12—Carbon filaments; Apparatus specially adapted for the manufacture thereof
  • D01F9/127—Carbon filaments; Apparatus specially adapted for the manufacture thereof by thermal decomposition of hydrocarbon gases or vapours or other carbon-containing compounds in the form of gas or vapour, e.g. carbon monoxide, alcohols
• • 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
  • C01B2203/0266—Processes for making hydrogen or synthesis gas containing a decomposition step
  • C01B2203/0277—Processes for making hydrogen or synthesis gas containing a decomposition step containing a catalytic decomposition 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
  • C01B2203/10—Catalysts for performing the hydrogen forming reactions
  • C01B2203/1041—Composition of the catalyst
  • C01B2203/1047—Group VIII metal catalysts
  • C01B2203/1052—Nickel or cobalt 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
  • C01B2203/1076—Copper or zinc-based 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
  • C01B2203/12—Feeding the process for making hydrogen or synthesis gas
  • C01B2203/1205—Composition of the feed
  • C01B2203/1211—Organic compounds or organic mixtures used in the process for making hydrogen or synthesis gas
  • C01B2203/1235—Hydrocarbons
  • C01B2203/1241—Natural gas or methane
• • 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
  • C01B2203/80—Aspect of integrated processes for the production of hydrogen or synthesis gas not covered by groups C01B2203/02 - C01B2203/1695
  • C01B2203/84—Energy production
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/50—Improvements relating to the production of bulk chemicals
  • Y02P20/584—Recycling of catalysts

Definitions

• This invention relates generally to the production of hydrogen, and more specifically to hydrogen production by the direct cracking of hydrocarbons such as methane and natural gas.
• the current proton-exchange membrane (PEM) fuel cells utilize hydrogen as the energy source and require essential elimination (ideally below 20 ppmv) of carbon monoxide from the hydrogen stream to prevent poisoning of the electrocatalyst.
• Hydrogen is typically produced through steam reforming, partial oxidation or autothermal reforming of natural gas. In all these cases, however, carbon monoxide is a co-product, which has to be converted into carbon dioxide in subsequent steps which adds to the cost of the produced hydrogen.
• An alternative route is to directly crack the hydrocarbon fuel into hydrogen and carbon.
• the formation of carbon oxides is avoided and the need for downstream reactions such as water-gas shift and selective oxidation for the conversion of carbon monoxide to carbon dioxide is eliminated.
• this approach has not been extensively studied. While commercial processes exist that utilize thermal cracking of methane at extremely high temperatures for the -2- production of acetylene and carbon black, hydrogen production via the catalytic cracking of methane has been only briefly considered in the past.
• the rates of methane conversion and hydrogen formation were found to be in ratio of 1:2, thus, verifying the reaction stoichiometry for methane cracking.
• the amounts of carbon deposited on the spent catalyst and methane reacted indicated a good closure of the carbon balance (100 ⁇ 5%).
• catalyst activity may be fully restored by regenerating the catalyst through oxidation in air or steam gasification.
• the process of the invention may be applicable to any other suitable hydrocarbon such as ethane, ethylene, propane, propylene, butane, pentane, hexane and mixtures thereof, and hydrocarbons with molecular weights in the gasoline and diesel range. Nevertheless, it is anticipated that the preferred -4- hydrocarbons will be methane and natural gas. During the catalytic cracking of higher molecular weight hydrocarbons, it is expected that several other undesirable products will be formed in addition to the hydrogen.
• activity measurements for the methane cracking reaction were conducted over a set of 9 Ni-Cu/SIO 2 catalysts in which the total metal amount (on a molar basis) was maintained constant at 2.6 mmole of metal/g of support while the ratio of Ni:Cu was varied from approximately 8:1 to approximately 1 :8.
• the reaction was carried out in a pure methane stream, at 650 and 800 °C and at a gas hourly space velocity of 6000 hr 1. The results indicate that the presence of small amounts of Cu enhanced significantly the Ni activity at 800 °C.
• the promoting effect is also more pronounced when small amounts of Cu are added (i.e., Ni:Cu ratios greater than 1).
• the highest initial methane conversion observed with these set of catalysts is at the 8:1 Ni:Cu ratio. Even higher initial methane conversions are expected with higher Ni:Cu ratios up to about 20:1.
• FIG. 1 represents a plot of the deactivation of a Ni/SiO 2 catalyst at 550°C
• GHSN 30,000 h "1 in a stream containing 20% CH 4 , in He;
• FIG. 2 represents a plot of methane conversions obtained over fresh (•, ⁇ ) and regenerated (O in air, ⁇ in steam) ⁇ i/SiO 2 catalyst at 550°C at two different space velocities; -5-
• Fig. 4 represents a plot of initial methane conversion as a function of catalyst composition at two different temperatures over a series of Ni-Cu/SiO 2 catalysts (O at 650 °C and D at 800°C).
• the catalyst used in the first embodiment of this invention was prepared by incipient wetness impregnation of an aqueous solution of nickel nitrate onto the silica support, followed by calcination in air and in-situ reduction in flowing hydrogen.
• This is a standard method of preparation of supported metal catalysts and several different nickel salts can be used instead of nickel nitrate as the nickel precursor.
• other standard methods for the preparation of supported metal catalysts could be used without having a detrimental effect on the properties of the catalyst.
• silica we investigated other inorganic supports such as alumina and titania.
• the catalyst used in the present invention will eventually deactivate as a result of carbon deposition.
• Carbon may deposit on the surface to cover the active sites (site-blocking) or accumulate at the entrance of the pores to block further access of the reactants to the interior (pore-mouth plugging). It has been estimated that in both cases catalyst deactivation would occur within a short period of time. Even if 10 carbon atoms are needed to block each surface ⁇ i atom, for example, 11 mg of carbon deposition would be enough to completely deactivate one gram of the 16.4% ⁇ i/SiO 2 catalyst. Furthermore, if pore-mouth plugging was the main deactivation mechanism, approximately 250 mg of carbon would be sufficient to clog the external 10% of the pores, in one gram of the Ni/SiO 2 catalyst sample.
• SEM SEM and Transmission Electron Microscopy (TEM) analyses of the spent catalysts were utilized to further understand the deactivation mechanism.
• SEM micrographs indicate the formation of filamentous carbon on the catalyst surface. These filaments appear to grow out of the silica support surface, with their length increasing with time-on-stream. Each filament has a bright tip, identified by the use of SEM/EDS (Energy Dispersive X-Ray Spectroscopy) to be a nickel particle.
• SEM/EDS Energy Dispersive X-Ray Spectroscopy
• Spent catalyst samples were further studied by the use of X-Ray Diffraction (XRD). The XRD patterns, suggest that graphitic carbon constituents with different degrees of defect or distortion are present in the deactivated samples.
• TEM micrographs of the fully deactivated sample show that the growth of the carbon is terminated as a result of spatial limitations.
• the modes of filament termination include the nickel particle's restriction by the silica surface, the arm and the tip of another carbon filament. Formation of carbon filaments as a result of hydrocarbon cracking has been extensively reported in the literature with higher molecular weight hydrocarbons over supported nickel, iron, cobalt and several alloy catalysts.
• the carbon deposited on the catalyst in carrying out the present invention may be used in electrochemical applications such as superconductors, electrodes and fuel cells.
• the oxidation process was faster than the steam gasification, but caused a high temperature front. This front gradually moved through the catalyst bed, causing the collapse of the sample to a fine powder.
• XRD analysis suggests that the oxidation process completely removed -8- the deposited carbon and converted the metallic nickel into nickel oxide which had to be reduced in flowing hydrogen before the next reaction cycle shown in Figure 2.
• the catalyst bed maintained a uniform temperature profile during the steam regeneration process and the catalyst preserved its metallic nickel form at the end of the process.
• the set of Ni-Cu/SiO 2 catalysts used in the second embodiment of this invention had the total metal amount (on a molar basis) maintained constant at 2.6 mmole of metal/g of support while the ratio of Ni:Cu was varied from approximately 8:1 to approximately 1 :8.
• the catalysts were prepared by incipient wetness impregnation of nickel and copper nitrates (Ni(NO 3 ) 2 x6H 2 O and Cu(NO 3 ) 2 x2.5H 2 O) obtained from Aldrich (with a purity of 99.999%) onto commercially available SiO 2 (Davison Syloid 74).
• the silica support Prior to impregnation the silica support was dried, pressed into pellets under a pressure of 15,000 psig, crushed and sieved to obtain a granulometric fraction in the 20-35 mesh size.
• the impregnated samples were dried in a vacuum oven at 120 °C overnight and subsequently calcined in a muffler furnace at 700 °C for 6 hours.
• the Ni and Cu loadings were estimated by the weight difference between the blank support and the catalyst reduced overnight in a 1 :2 H 2 /N 2 mixture (total flow rate of 120 ml/min) at 650 °C .

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• 1999
  • 1999-02-19 CA CA002317395A patent/CA2317395A1/en not_active Abandoned
  • 1999-02-19 CN CN99803169A patent/CN1291165A/zh active Pending
  • 1999-02-19 AU AU26873/99A patent/AU2687399A/en not_active Abandoned
  • 1999-02-19 WO PCT/US1999/003556 patent/WO1999043608A1/en not_active Application Discontinuation
  • 1999-02-19 EP EP99907144A patent/EP1060123A1/de not_active Withdrawn

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