WO2009095513A2 - Hydrogen production comprising the decomposition of light hydrocarbons, catalysed by mesostructured carbonaceous materials - Google Patents

Hydrogen production comprising the decomposition of light hydrocarbons, catalysed by mesostructured carbonaceous materials Download PDF

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WO2009095513A2
WO2009095513A2 PCT/ES2009/000032 ES2009000032W WO2009095513A2 WO 2009095513 A2 WO2009095513 A2 WO 2009095513A2 ES 2009000032 W ES2009000032 W ES 2009000032W WO 2009095513 A2 WO2009095513 A2 WO 2009095513A2
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hydrogen
catalyst
decomposition
light hydrocarbons
carbon
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PCT/ES2009/000032
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French (fr)
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WO2009095513A4 (en
WO2009095513A3 (en
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David Pedro Serrano Granados
Juan Angel Botas Echevarria
Guillermo Calleja Pardo
Patricia Pizarro De Oro
Ruth Guil Lopez
Gema Gomez Pozuelo
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Universidad Rey Juan Carlos
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    • 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
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/18—Carbon
    • 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
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/64—Pore diameter
    • B01J35/647—2-50 nm
    • 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
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/66—Pore distribution
    • B01J35/67—Pore distribution monomodal
    • 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
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/66—Pore distribution
    • B01J35/69—Pore distribution bimodal
    • 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
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
    • B01J37/0018—Addition of a binding agent or of material, later completely removed among others as result of heat treatment, leaching or washing,(e.g. forming of pores; protective layer, desintegrating by heat)
    • 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
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08—Heat treatment
    • B01J37/082—Decomposition and pyrolysis
    • B01J37/084—Decomposition of carbon-containing compounds into carbon
    • 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
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/03—Catalysts comprising molecular sieves not having base-exchange properties
    • B01J29/0308—Mesoporous materials not having base exchange properties, e.g. Si-MCM-41
    • 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
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/61—Surface area
    • B01J35/618—Surface area more than 1000 m2/g
    • 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
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/63—Pore volume
    • B01J35/638—Pore volume more than 1.0 ml/g

Definitions

  • the present invention describes the production of hydrogen by catalytic decomposition of methane and other light hydrocarbons at temperatures between 600-1400 0 C, using as catalysts mesostructured carbonaceous materials of high specific surface area, with a regular distribution of pore sizes in the range 2-50 nm
  • the present invention describes the obtaining of hydrogen by means of methanocatalytic decomposition of methane and other light hydrocarbons, using as catalysts mesostructured materials of high specific surface area with regular distribution of pore sizes, in the range 2-50 nm.
  • Hydrogen is considered the most promising alternative as an energy vector. Its use as a fuel, either in combustion systems or in fuel cells, produces non-polluting emissions, since water is obtained as a product of the oxidation reaction of hydrogen.
  • Currently, the most widespread route for hydrogen production consists in reforming methane with water vapor.
  • the hydrogen required in the manufacture of methanol and ammonia is usually obtained by reforming natural gas with water vapor.
  • M. Steinberg carried out a comparative analysis from the energy and environmental point of view of the different processes available for the production of hydrogen as fuel, including both those based on the use of renewable energy sources and those that employ fossil fuels [M . Steinberg, "The Hy-C Process (Thermal Decomposition of Natural Gas) Potentially the Lowest Cost Source of Hydrogen with the least CO 2 Emission”, Energy Convers. Mgmt., 1995, 36 (6-9), 791; M. Steinberg, "Production of Hydrogen and Methanol from Natural Gas with Reduced CO 2 Emission”, Int. J. Hydrogen Energy, 1998, 23 (6), 419]. While
  • SUBSTITUTE SHEET (RULE 26)
  • the reforming of methane with water vapor is the process of lower energy consumption, its high emissions of CO 2 , as well as the presence of traces of CO in the stream of hydrogen produced, which constitutes a poison for the electrocatalysts present in the batteries of fuel, represent an important impediment to its implementation in the production of hydrogen as fuel for batteries.
  • the reformed biomass, but overall net free CO 2 has costs very high production. Processes based on the use of other energy sources, such as renewable energies (solar, geothermal, hydraulic, wind, etc.) present as inconvenient their high energy consumption or limited geographical availability.
  • Thermal decomposition or methane thermocatalytic represents one of the potentially most viable alternative the hydrogen production due to a moderate power consumption, low or zero CO 2 emissions and the possibility of marketing the solid carbonaceous product generated.
  • the patent application JP 2003063801 refers to a process of thermal decomposition of methane in which the production of hydrogen is carried out by decomposition of a hydrocarbon dissolved in supercritical water, using nuclear energy as a thermal source of the process.
  • the patent application WO2003010088 uses a non-thermal plasma of dielectric barrier discharge as an energy source to generate hydrogen and carbon through the decomposition of methane or natural gas.
  • Patent application KR2004035998 refers to a method to simultaneously generate hydrogen and carbon black, including the design of the reactor, based on a double-tube system to avoid operating stops caused by carbon deposits.
  • Thermocatalytic decomposition processes offer the advantage of requiring lower temperatures than those of the processes performed in the absence of catalyst, where the reaction temperatures usually range from 0 C to 1200, even 2000 0 C.
  • One of transition metals more used as a catalyst for the decomposition of methane is nickel, characterized by producing hydrogen and carbon nanotubes through the decomposition of methane, without CO emissions and at temperatures between 450 and 850 ° C.
  • Patent application JP2003054904 refers to the application of nickel supported on a USY-type zeolite as a catalyst for the production of hydrogen by means of the transformation of methane and other light hydrocarbons.
  • the patent application WO 2006040788 refers to the use of granules of NdNi 5 for the decomposition of methane at temperatures in the range 500-550 0 C, obtaining hydrogen and carbon nanotubes as reaction products.
  • patent application WO2000021878 describes a method and device for the continuous production of hydrogen and carbon by means of pyrolysis of methane, natural gas or other organic gases.
  • the reactor operates under a temperature gradient from 300 to 2000 0 C, using as a black powder carbon catalyst, which is self-supplied by the reaction system itself.
  • N. Muradov et al. Describe the use of commercial carbonaceous materials as catalysts for thermocatalytic decomposition of methane using a fixed bed reactor [N. Muradov; F. Smith; A. T-Raiss ⁇ , "Catalytic activity of carbons for methane decomposition reaction", Catal. Today, 2005, 102-103, 225].
  • This work summarizes the results obtained from the use of many types of commercial carbonaceous materials studied to catalyze the decomposition of methane, carrying out the study of the initial catalytic activity through the initial reaction rate. This study shows that, under these conditions, the higher initial catalytic activity Ia has activated carbon and carbon blacks with a high specific surface area.
  • the work does not present studies on the durability of the catalysts, however, the rapid deactivation of activated carbons under study is manifested.
  • AM Dunker et al. have studied the deactivation of carbon blacks during the catalytic decomposition of methane carried out in a fluidized bed reactor [AM Dunker; S. Kumar; PA Mulawa, "Production of hydrogen by thermal decomposition of methane in a fluidized-bed reactor: Effects of catalyst, temperature, and residence time", Int. J. Hydrogen Energy, 2006, 31 (4), 473]
  • the use of a fluidized bed reactor decreases the deactivation, increasing the amount of carbon produced, reaching 5 g of carbon produced per gram of catalyst after 33.3 h of reaction at 925 0 C.
  • the vast majority Commercial carbonaceous materials undergo a progressive deactivation as a result of the clogging of their micropores by the deposits of the generated carbon, which also have less activity than the initial catalyst.
  • mesoporous or mesostructured carbonaceous materials have been developed by different methods of nano-replication or nano-molding based on the use of inorganic solid molds (exo-molding) or other organic compounds in solution (endo-nanomolding), which act as agents directors of the carbon mesostructure. These materials are characterized by a system of perfectly defined pores, of regular geometry and size, in the range of mesopores (2-50 nm).
  • the synthesis of mesostructured carbonaceous materials by nanoreplication of inorganic molds consists in the impregnation of a highly ordered inorganic solid with a carbon precursor and the subsequent polymerization of the carbon precursor at a higher temperature. After subjecting the assembly to a carbonization stage at elevated temperatures under an inert atmosphere, the inorganic mold is removed by treatment with HF or with a NaOH solution, generating the corresponding mesostructured carbonaceous material.
  • precursors of carbon sucrose, furfuryl alcohol, acenaphthene and acetylene have been used, among others.
  • SUBSTITUTE SHEET (RULE 26) As an inorganic mold, mesostructured silicates or aluminosilicates having an interconnected pore structure can be used. The polymerization of the carbon source is catalyzed by the Al centers, if an aluminosilicate is used as an inorganic mold, or an appropriate catalyst, such as oxalic acid or sulfuric acid, can be added to the impregnation medium.
  • CMK-2 carbonaceous structures that are negative of the inorganic mold
  • CMK-3 carbonaceous structures that are negative of the inorganic mold
  • CMK-4 from MCM-48
  • Nanotube structures can be generated by formation of carbon sheets inside the pores of the mold (CMK-5, from SBA-15)
  • other structures can also be obtained by modifications in the synthesis (CMK-1, from MCM-48) [R. Ryoo; SH Joo; S. Jun, "Ordered mesoporous molecular carbon sieves by templated synthesis: the structural varieties", Stud. Surf. Sci. Catal., 2001, 135, 1121].
  • Jaroniec "Adsorption and structural properties of ordered mesoporous carbons synthesized by using various carbon precursors and ordered siliceous P6mm and Ia3d mesostructures as templates", J. Phys. Chem. B, 2005, 109 (49), 23263].
  • the technique consists in carrying out the polymerization, in solution, of the precursor molecules of carbon around organic molecules organized in the form of supramolecular entities or micelles, with those that are assembled through different interaction mechanisms. After the polymerization stage, the material is carbonized under an inert atmosphere, with the consequent removal of the mold by pyrolysis reactions.
  • the carbon precursors and organic molds commonly used are resins of the resol type (phenol, resorcinol, formaldehyde, etc.) and block copolymers (Pluronic P-123, F-127, etc.), respectively, being able to obtain highly mesoporous carbonaceous materials. ordered with different structures and controlled textural properties, depending on the synthesis conditions used [CD. Liang; KJ Hong; G.A. Guiochon; J.W. Mays; S. Dai, "Synthesis of a large-scale highly ordered porous carbon film by self-assembly of block copolymers", Angew. Chem. Int. Ed.,
  • the present invention relates to the use of mesoporous carbonaceous materials of high specific surface area with regular distribution of pores, hereinafter mesostructured carbonaceous materials, as catalysts in hydrogen production.
  • mesostructured carbonaceous materials hereinafter mesostructured carbonaceous materials
  • the present invention provides a process with which carbon productions could be achieved, by methane decomposition, greater than 11 times the initial mass of carbonaceous catalyst used, which is equivalent to more than 41 L of hydrogen produced by each gram of carbonaceous catalyst used, without deactivation of the catalyst during the reaction time and with low or zero carbon oxides content in the output stream.
  • the present invention relates to a process for the selective production of hydrogen by thermocatalytic decomposition of light hydrocarbons characterized in that the decomposition of hydrocarbons is catalyzed by a catalyst of mesostructured carbonaceous material.
  • the light hydrocarbons referred to in the present invention comprise between 1 and 4 carbon atoms. In another more particular aspect, light hydrocarbons are linear. In another more particular aspect, the
  • hydrocarbons are branched.
  • the hydrocarbon of the present invention refers to methane.
  • thermocatalytic decomposition of hydrocarbons is carried out at a temperature between 600 - 1400 0 C, preferably between 700 to 1150 0 C.
  • thermocatalytic decomposition of hydrocarbons is carried out at a pressure between 1-20 atmospheres, preferably at atmospheric pressure.
  • the catalytic decomposition of hydrocarbons of the present invention can be carried out in continuous or semi-continuous reactors of the tray type, fluidized bed, its application being extensive to any gas-solid reactor.
  • the mesostructured material has a regular distribution of pore size between 2-50 nm.
  • the mesostructured carbonaceous material has a specific surface area between 200 and 3000 m 2 g "1 .
  • the mesostructured carbonaceous material has a pore volume comprised between 0.5-2 cm 3 g '1
  • the mesostructured carbonaceous material has a unique pore system with a narrow pore size distribution of 30 ⁇ .
  • the mesostructured carbonaceous material has a bimodal pore system with a pore size of 30 and 50 ⁇ .
  • the present invention refers to a catalyst characterized in that it is a mesostructured carbonaceous material with a regular distribution of pore sizes comprised between 2-50 nm, a specific surface area between 200 and 3000 m 2 g ⁇ a pore volume between 0.5 - 2 cm 3 g "1 .
  • the mesostructured carbonaceous material catalyst of the present invention has a unique pore system with a narrow pore size distribution of 30 ⁇ .
  • the mesostructured carbonaceous material catalyst of the present invention has a bimodal system of pores with a pore size of 30 and 50 ⁇ .
  • the present invention refers to the use of a catalyst of the present invention in the selective production of hydrogen by thermocatalytic decomposition of light hydrocarbons.
  • Figure 1 represents the comparison of the evolution of the mass of carbon as a function of time, between the mesostructured carbonaceous catalyst CM-a and the carbon black Black Pearls 2000 (Cabot Corp.), during the reaction of. thermocatalytic decomposition of methane at programmed temperature.
  • Figure 2 shows the comparison of the evolution of the carbon mass as a function of time, between the mesostructured carbonaceous catalyst CM-b and the carbon black Black Pearls 2000 (Cabot Corp.), during the thermocatalytic decomposition reaction of methane a set temperature
  • Figure 3 shows the comparison of the evolution of the mass of carbon produced as a function of time, between the mesostructured carbonaceous material CM-b and the carbon black Black Pearls 2000 (Cabot Corp.), during the thermocatalytic decomposition reaction of methane at a constant temperature of 900 0 C.
  • Figure 4 shows the comparison of the evolution of the carbon mass as a function of the operating time, between the CM-b mesostructured carbonaceous material and the Black Pearls 2000 (Cabot Corp.) carbon black, during the thermocatalytic decomposition reaction of methane at a constant temperature of 1000 0 C.
  • thermocatalytic decomposition reaction of light hydrocarbons using mesostructured carbonaceous materials as catalysts is carried out according to conventional procedures in a continuous or semicontinuous reactor of the tray, fixed bed or fluidized bed type, its application being extended to any Gas-Solid reactor.
  • the reaction can be carried out in the pressure range between atmospheric and 10 atmospheres, being preferable at atmospheric pressure.
  • the reaction is carried out at programmed temperature or isothermal experiments, at a temperature between 600 and 1400 0 C, preferably between 700 and 1150
  • SUBSTITUTE SHEET (RULE 26) Linear or branched light hydrocarbons with a number of carbons between 1 and 4 are used in the process, methane being preferable because of its higher relative hydrogen content.
  • thermocatalytic decomposition reaction of light hydrocarbons using mesostructured carbonaceous materials as catalysts can also be carried out in the presence of inert diluents, such as helium, nitrogen or argon.
  • inert diluents such as helium, nitrogen or argon.
  • the decomposition of methane catalyzed by mesostructured carbonaceous materials is carried out with a commercial reaction mixture of 10% methane in argon.
  • the mesostructured carbonaceous catalyst is used in the form of particles of different sizes. The catalyst is introduced into a reactor equipped with devices for measuring the temperature and a heating element.
  • the reactor is an alumina tray reactor, at which bottom the catalyst is supported forming a catalytic bed.
  • An electric oven is used as a heating element of the reactor.
  • the reactor has a thermocouple to measure the temperature whose sensor element is at its base.
  • the catalysts referred to in the present invention are mesoporous carbonaceous materials of high specific surface area, the preparation of which is detailed below:
  • the ordered mesoporous or mesostructured carbonaceous materials of high specific surface area with different ordered pore systems are prepared by means of the exo-nanomolding technique according to procedures set forth in the literature.
  • a non-limiting example of the preparation of a high-surface mesoporous carbonaceous material with two highly ordered pore systems can be found in the method described by A.-H. Lu et al [An-HU ⁇ LU; Wen-Cui Li; Wolfgang Schmidt; Wolfgang Kiefer; Ferdi Schüth, "Easy synthesis of an ordered mesoporous carbon with a hexagonally packed tubular structure", Carbon, 2004, 42 (14), 2939].
  • mesostructured carbonaceous materials begins with the synthesis of a highly ordered mesoporous inorganic mold, with at least
  • SUBSTITUTE SHEET (RULE 26) two different and interconnected pore systems. Said inorganic mold will be determinant in the porosity of the final carbonaceous material.
  • a non-limiting example of the preparation of a highly ordered mesoporous inorganic mold is found in the preparation of purely siliceous SBA-15 material detailed by D. Zhao et al. [Dongyuan Zhao, Jianglin Feng, Qisheng Huo, Nicholas Melosh, Glenn H. Fredrickson Bradley F. Chmelka, Galen D. Stucky, "Triblock Copolymer Syntheses of Mesoporous Silica with Periodic 50 to 300 Angstrom Pores", Science, 1998, 279 (5350), 548].
  • the mesostructured inorganic mold is prepared, its entire porous surface is covered with an organic prepolymer by impregnation, vapor deposition or by any of the existing methods for coating the porous surface of one material with another. Subsequently, the organic prepolymer polymerizes, with the use or not of temperature and the use or not of a polymerization catalyst, and the polymer, already formed, is carbonized at elevated temperature under an inert atmosphere, such as helium or argon.
  • an inert atmosphere such as helium or argon.
  • the last stage of the preparation of highly ordered mesoporous carbonaceous materials is the removal of the inorganic mold, by one or several washes with a solvent that selectively dissolves the inorganic mold, such as a solution of sodium hydroxide or a solution of hydrofluoric acid .
  • EXAMPLE 1 Decomposition of methane at programmed temperature catalyzed by a mesostructured carbonaceous material with a single pore system (CM-a), synthesized by exo-nanomolding.
  • CM-a mesostructured carbonaceous material with a single pore system
  • CM-a mesostructured carbonaceous material with a single pore system
  • the preparation of the mesostructured carbonaceous material with a single pore system (CM-a) was performed according to the procedure described by A.-H. Lu et al [Piotr A. Bazula, An-Hui Lu, Jórg-Joachim Nitz, Ferdi Schüth, "Surface and pore structure modification of ordered mesoporous carbons via a chemical oxidation approach"; Microporous and Mesoporous Materials, 2008, 108 (1-3), 266].
  • 0.006 grams of oxalic acid were dissolved in 1.5 mL of furfuryl alcohol, at room temperature. The resulting solution was introduced, by impregnation to incipient moisture, into the pores of 1 gram of the inorganic mold SBA-15.
  • the impregnated solid was subjected to three consecutive thermal treatments in static air: 50 0 C for 12 hours, 70 0 C for 12 hours and 90 0 C for 48 more hours.
  • the solid obtained was treated, under argon, heating to a temperature of 90 0 C at 5 ° C min '1, then increasing the temperature to 150 0 C at 1 0 C min "1, and this temperature was maintained for 180 minutes, then the temperature was increased to 300 C at a rate of 1 ° C min ⁇ 1 , this temperature being maintained for 5 minutes, after which the temperature was increased again to 850 0 C at the rate of 5 ° C min '1 , keeping this temperature for 180 minutes, always under an argon atmosphere.
  • the inorganic mold SBA-15 was extracted with a 1M solution of sodium hydroxide composed of 3 grams of sodium hydroxide, 50 mL of distilled water and 20 mL of absolute ethanol, for every gram of SBA-15 to be removed, keeping the mixture at 50 0 C for 24 hours.
  • the resulting mesostructured carbonaceous material was washed ten times with each of the following solvents: distilled water, absolute ethanol, 0.15 M nitric acid, distilled water and acetone. The solid was dried at 90 0 C for 12
  • the highly ordered mesoporous carbonaceous material obtained in this way had a specific surface area of 1300 m 2 g '1 , a pore volume of 1.1 cm 3 g "1 and a narrow distribution of pore sizes centered around 30 amstrong.
  • This mesostructured carbonaceous material with a single pore system was identified as CM-a.
  • CM-a mesostructured carbonaceous material with a single pore system
  • thermocouple was located for measuring the temperature, whose sensor element was located in the center of the tray reactor base.
  • An electric oven was used as heating element of the reactor.
  • the catalyst bed was treated with a rate of 100 ml_ (STP) / min [milliliters of gas in standard conditions of temperature and pressure (1 atm, 25 0 C) per minute] of pure nitrogen and raising the temperature from the ambient up to 250 ° C in a total time of 12.5 minutes. Then, the temperature was lowered to 50 ° C and the catalyst bed feed was changed to the methane / argon reactive mixture.
  • the activity of the catalytic bed was evaluated by feeding a flow rate of 100 ml_ (STP) / min of a commercial reactive mixture of 10% methane / 90% argon (volumetric proportions) and raising the temperature from the ambient to 1 100 0 C in a time 105 minutes total. Once the temperature of 1100 0 C was reached, it was maintained for 45 min. The follow-up of the evolution of the reaction was carried out through the variation of mass that the solid experiences as a result of the carbon deposition, knowing the stoichiometry of the reaction:
  • SUBSTITUTE SHEET (RULE 26) The increase in mass was due to carbon production, a byproduct of the reaction. The weight gain was monitored by thermogravimetry, a technique that provided the carbon yield associated with the hydrogen yield.
  • Figure 1 represents the comparison of the evolution of the carbon mass as a function of time, between the mesostructured carbonaceous catalyst CM-a and the carbon black Black Pearls 2000 (Cabot Corp.), during the decomposition reaction thermocatalytic methane at programmed temperature.
  • EXAMPLE 2 Decomposition of methane to hydrogen at programmed temperature catalyzed by a mesostructured carbonaceous material with double pore system (CM-b) synthesized by exo-nanomolding.
  • CM-b mesostructured carbonaceous material with double pore system
  • the process of preparing the mesostructured carbonaceous material with double pore system by exo-nanomolding was analogous to that described in Example 1, with the proviso that the impregnation of the SBA-15 mold was carried out with a solution of 0.003 g of oxalic acid, 0.75 ml_ of furfuryl alcohol and 0.75 ml_ of trimethylbenzene, maintaining a concentration of 50% trimethylbenzene furfuryl alcohol in volume and an oxalic acid / furfuryl alcohol molar ratio of 0.004.
  • the resulting carbon material possessed a highly ordered porous structure, with a specific surface area of approximately 2000 m 2 g "1 , a total pore volume of 2 cm 3 g " 1 and a bimodal distribution of pore sizes, with average sizes of 30 and 50 amstrong, respectively.
  • Figure 2 shows the comparison of the evolution of the carbon mass as a function of time, between the mesostructured carbonaceous catalyst
  • SUBSTITUTE SHEET (RULE 26) CM-b and carbon black Black Pearls 2000 (Cabot Corp.), which has been taken, analogously to Example 1, as a reference catalyst.
  • EXAMPLE 3 Decomposition of methane to hydrogen at a constant temperature of 900 0 C catalyzed carbonaceous material mesostructured dual pore system (CM-b) synthesized by exo-nanomoldeo.
  • the synthesis of the mesostructured carbonaceous material CM-b was carried out according to the procedure described in Example 2.
  • the procedure for loading the catalyst in the reaction system, as well as the reaction installation employed, were analogous to those described in the examples. 1 and 2.
  • the temperature was lowered to 50 0 C, to stabilize the measurement, and became to raise the temperature from 50 0 C to 900 0 C in a total time of 45 minutes.
  • the catalytic bed feed was changed by the reactive methane / argon mixture.
  • the evaluation of the activity of the catalytic bed was carried out by feeding a flow rate of 100 mL (STP) / min of a commercial mixture 10% methane / 90% argon (volumetric proportions). The temperature was kept constant at 900 0 C for 170 min.
  • CM-b mesostructured carbonaceous catalyst with double pore system
  • Figure 3 shows the comparison of the evolution of the mass of carbon produced as a function of time, between the mesostructured carbonaceous material CM-b and the carbon black Black Pearls 2000 (Cabot Corp.), during the reaction of thermocatalytic decomposition of methane at a constant temperature of 900 0 C.
  • EXAMPLE 4 Decomposition of methane to hydrogen at a constant temperature of 1000 ° C catalyzed by a mesostructured carbonaceous material with double pore system (CM-b), synthesized by exo-nanomolding.
  • CM-b mesostructured carbonaceous material with double pore system
  • SUBSTITUTE SHEET (RULE 26) Catalyst treatment steps with a flow rate of 100 ml_ (STP) / min of pure nitrogen and heating at 250 "C, the temperature was lowered to 50 0 C, to stabilize the measurement, and the temperature was raised again from 50 ° C up to 1000 0 C in a total time of 50 minutes Once the 1000 0 C was reached, the catalytic bed feeding was changed by the reactive methane / argon mixture The evaluation of the catalytic bed activity was carried out by feeding a flow 100 ml_ (STP) / min of a commercial mixture 10% methanol / 90% argon (volume ratio). The temperature was kept constant at 1000 0 C for a period of 280 min.
  • thermocatalytic decomposition methane hydrogen at constant temperature of 1000 0 C was determined by comparing the catalytic activity of a commercial carbon (Black Pearls 2000 carbon black from the Cabot Corp. house), using the same reaction conditions to be able to make a comparison of the quantities of carbon and hydrogen produced.
  • the results obtained in the thermocatalytic decomposition of methane to hydrogen at constant temperature of 1000 0 C in the presence of commercial carbon black Black Pearls 2000 Cabot Corp. using the same reaction conditions described above are shown in Table 8.
  • Figure 4 shows the comparison of the evolution of the carbon mass as a function of the operating time, between the CM-b mesostructured carbonaceous material and the Black Pearls 2000 (Cabot Corp.) carbon black, during the reaction thermocatalytic decomposition of methane at a constant temperature of 1000 0 C.

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Abstract

The invention relates to a method for obtaining hydrogen, comprising the thermocatalytic decomposition of light hydrocarbons, in which the catalysts used take the form of mesostructured carbonaceous materials having a high specific surface area and a regular pore-size distribution of between 2 and 50 nm.

Description

PRODUCCIÓN DE HIDRÓGENO MEDIANTE DESCOMPOSICIÓN DE HIDROCARBUROS LIGEROS CATALIZADA POR MATERIALES CARBONOSOS MESOESTRUCTURADOS HYDROGEN PRODUCTION THROUGH DECOMPOSITION OF LIGHT HYDROCARBONS CATALYZED BY MESOSTRUCTURED CARBON MATERIALS
CAMPO DE LA INVENCIÓNFIELD OF THE INVENTION
En Ia presente invención se describe Ia producción de hidrógeno por descomposición catalítica de metano y otros hidrocarburos ligeros a temperaturas entre 600-1400 0C, utilizando como catalizadores materiales carbonosos mesoestructurados de elevada superficie específica, con una distribución regular de tamaños de poro en el intervalo 2-50 nm.The present invention describes the production of hydrogen by catalytic decomposition of methane and other light hydrocarbons at temperatures between 600-1400 0 C, using as catalysts mesostructured carbonaceous materials of high specific surface area, with a regular distribution of pore sizes in the range 2-50 nm
Estado de Ia TécnicaState of the Technique
En Ia presente invención se describe Ia obtención de hidrógeno mediante descomposición temnocatalítica de metano y otros hidrocarburos ligeros, empleando como catalizadores materiales carbonosos mesoestructurados de elevada superficie específica con distribución regular de tamaños de poro, en el intervalo 2-50 nm.The present invention describes the obtaining of hydrogen by means of methanocatalytic decomposition of methane and other light hydrocarbons, using as catalysts mesostructured materials of high specific surface area with regular distribution of pore sizes, in the range 2-50 nm.
El hidrógeno está considerado como Ia alternativa más prometedora como vector energético. Su uso como combustible, bien en sistemas de combustión o en pilas de combustible, produce emisiones no contaminantes, ya que como producto de Ia reacción de oxidación del hidrógeno se obtiene agua. Actualmente Ia vía más extendida para Ia producción de hidrógeno consiste en el reformado de metano con vapor de agua. A modo de ejemplo, cabe indicar que el hidrógeno requerido en Ia fabricación de metanol y amoníaco se obtiene habitualmente por reformado de gas natural con vapor de agua.Hydrogen is considered the most promising alternative as an energy vector. Its use as a fuel, either in combustion systems or in fuel cells, produces non-polluting emissions, since water is obtained as a product of the oxidation reaction of hydrogen. Currently, the most widespread route for hydrogen production consists in reforming methane with water vapor. By way of example, it should be noted that the hydrogen required in the manufacture of methanol and ammonia is usually obtained by reforming natural gas with water vapor.
M. Steinberg realizó un análisis comparativo desde el punto de vista energético y ambiental de los diferentes procesos disponibles para Ia producción de hidrógeno como combustible, incluyendo tanto aquellos que se basan en el uso de fuentes de energía renovables como los que emplean combustibles fósiles [M. Steinberg, "The Hy-C Process (Thermal Decomposition of Natural Gas) Potentially the Lowest Cost Source of Hydrogen with the least CO2 Emission", Energy Convers. Mgmt., 1995, 36(6-9), 791 ; M. Steinberg, "Production of Hydrogen and Methanol from Natural Gas with Reduced CO2 Emission", Int. J. Hydrogen Energy, 1998, 23(6), 419]. Mientras queM. Steinberg carried out a comparative analysis from the energy and environmental point of view of the different processes available for the production of hydrogen as fuel, including both those based on the use of renewable energy sources and those that employ fossil fuels [M . Steinberg, "The Hy-C Process (Thermal Decomposition of Natural Gas) Potentially the Lowest Cost Source of Hydrogen with the least CO 2 Emission", Energy Convers. Mgmt., 1995, 36 (6-9), 791; M. Steinberg, "Production of Hydrogen and Methanol from Natural Gas with Reduced CO 2 Emission", Int. J. Hydrogen Energy, 1998, 23 (6), 419]. While
HOJA DE SUSTITUCIÓN (REGLA 26) el reformado de metano con vapor de agua es el proceso de menor consumo energético, sus elevadas emisiones de CO2, así como Ia presencia de trazas de CO en Ia corriente de hidrógeno producido, el cual constituye un veneno para los electrocatalizádores presentes en las pilas de combustible, suponen un importante impedimento para su implantación en Ia producción de hidrógeno como combustible para pilas. El reformado de biomasa, aunque globalmente libre de emisiones netas de CO2, presenta costes de producción muy elevados. Los procesos basados en el empleo dé otras fuentes de energía, tales como las energías renovables (solar, geotérmica, hidráulica, eólica, etc.) presentan como inconveniente su elevado consumo energético o su disponibilidad geográfica limitada.SUBSTITUTE SHEET (RULE 26) The reforming of methane with water vapor is the process of lower energy consumption, its high emissions of CO 2 , as well as the presence of traces of CO in the stream of hydrogen produced, which constitutes a poison for the electrocatalysts present in the batteries of fuel, represent an important impediment to its implementation in the production of hydrogen as fuel for batteries. The reformed biomass, but overall net free CO 2 has costs very high production. Processes based on the use of other energy sources, such as renewable energies (solar, geothermal, hydraulic, wind, etc.) present as inconvenient their high energy consumption or limited geographical availability.
La descomposición térmica o termocatalítica de metano representa una de las alternativas potencialmente más viables para Ia producción de hidrógeno debido a un consumo energético moderado, su mínima o incluso nula emisión de CO2 y a Ia posibilidad de comercializar el producto sólido carbonoso generado. La solicitud de patente JP 2003063801 , se refiere a un proceso de descomposición térmica de metano en el que Ia producción de hidrógeno se realiza mediante descomposición de un hidrocarburo disuelto en agua supercrítica, empleando energía nuclear como fuente térmica del proceso.Thermal decomposition or methane thermocatalytic represents one of the potentially most viable alternative the hydrogen production due to a moderate power consumption, low or zero CO 2 emissions and the possibility of marketing the solid carbonaceous product generated. The patent application JP 2003063801, refers to a process of thermal decomposition of methane in which the production of hydrogen is carried out by decomposition of a hydrocarbon dissolved in supercritical water, using nuclear energy as a thermal source of the process.
La solicitud de patente WO2003010088, emplea un plasma no térmico de descarga de barrera dieléctrica como fuente de energía para generar hidrógeno y carbono mediante Ia descomposición de metano o gas natural.The patent application WO2003010088, uses a non-thermal plasma of dielectric barrier discharge as an energy source to generate hydrogen and carbon through the decomposition of methane or natural gas.
La solicitud de patente KR2004035998 se refiere a un método para generar simultáneamente hidrógeno y negro de carbono, incluyendo el diseño del reactor, basado en un sistema de doble tubo para evitar las paradas de operación provocadas por los depósitos de carbono.Patent application KR2004035998 refers to a method to simultaneously generate hydrogen and carbon black, including the design of the reactor, based on a double-tube system to avoid operating stops caused by carbon deposits.
Los procesos de descomposición termocatalítica ofrecen Ia ventaja de requerir temperaturas inferiores a las de los procesos realizados en ausencia de catalizador, donde las temperaturas de reacción comprenden habitualmente desde los 1200 0C hasta, incluso, los 2000 0C. Uno de los metales de transición más empleados como catalizador para Ia descomposición de metano és el níquel, caracterizado por producir hidrógeno y nanotubos de carbono mediante Ia descomposición de metano, sin emisiones de CO y a temperaturas entre 450 y 850 °C.Thermocatalytic decomposition processes offer the advantage of requiring lower temperatures than those of the processes performed in the absence of catalyst, where the reaction temperatures usually range from 0 C to 1200, even 2000 0 C. One of transition metals more used as a catalyst for the decomposition of methane is nickel, characterized by producing hydrogen and carbon nanotubes through the decomposition of methane, without CO emissions and at temperatures between 450 and 850 ° C.
Entre las patentes que describen el empleo de catalizadores de níquel para Ia descomposición de metano se encuentra Ia solicitud de patente RU 2071932.Among the patents that describe the use of nickel catalysts for the decomposition of methane is the patent application RU 2071932.
HOJA DE SUSTITUCIÓN (REGLA 26) La solicitud de patente JP2003054904 se refiere a Ia aplicación de níquel soportado sobre una zeolita tipo USY como catalizador para Ia producción de hidrógeno mediante Ia transformación de metano y otros hidrocarburos ligeros .SUBSTITUTE SHEET (RULE 26) Patent application JP2003054904 refers to the application of nickel supported on a USY-type zeolite as a catalyst for the production of hydrogen by means of the transformation of methane and other light hydrocarbons.
En Ia solicitud de patente US2004118047 se describe un proceso y una instalación para Ia producción catalítica de hidrógeno a partir de metano o de corrientes gaseosas ricas en metano, basado en el empleo de catalizadores constituidos por al menos un metal del grupo VIII de Ia tabla periódica, como fase activa, y un material inorgánico como soporte. La instalación utilizada consiste en dos reactores dispuestos en paralelo, uno de ellos operando en modo de reacción, a una temperatura entre 600 y 1000 0C, y el otro en fase de regeneración, con el fin de evitar paradas debido a Ia formación de depósitos de carbono.In the patent application US2004118047 a process and an installation for the catalytic production of hydrogen from methane or methane-rich gaseous streams are described, based on the use of catalysts constituted by at least one metal of group VIII of the periodic table , as an active phase, and an inorganic material as support. The installation used consists of two reactors arranged in parallel, one of them operating in reaction mode, at a temperature between 600 and 1000 0 C, and the other in the regeneration phase, in order to avoid stops due to the formation of deposits carbon
En Ia solicitud de patente US2005063900 se describe el uso de materiales con composiciones NixMgγO ó NiχMgγCuzO, siendo las temperaturas de reacción para Ia descomposición del metano en presencia de dichos catalizadores entre 500-550 0C ó 700-760 0C, respectivamente.The patent application US2005063900 describes the use of materials with compositions Ni x Mg γ O or NiχMgγCu z O, the reaction temperatures for the decomposition of methane in the presence of said catalysts between 500-550 0 C or 700-760 0 C, respectively.
La solicitud de patente WO 2006040788 se refiere al uso de granulos de NdNi5 para Ia descomposición de metano a temperaturas en el intervalo 500-550 0C, obteniéndose como productos de reacción hidrógeno y nanotubos de carbono.The patent application WO 2006040788 refers to the use of granules of NdNi 5 for the decomposition of methane at temperatures in the range 500-550 0 C, obtaining hydrogen and carbon nanotubes as reaction products.
En Ia solicitud de patente US 2006198782 se describe otra variante a los catalizadores de níquel En dicha solicitud de patente, se describe Ia descomposición de metano empleando partículas de óxido de níquel obtenidas por precipitación.In US patent application 2006198782 another variant to nickel catalysts is described. In said patent application, the decomposition of methane using nickel oxide particles obtained by precipitation is described.
Aunque de manera menos extendida, también se han empleado otros catalizadores metálicos para Ia producción de hidrógeno a partir de metano. Por ejemplo, en Ia solicitud de patente JP 07025601 , se describe el uso de catalizadores consistentes en elementos del grupo VIII de Ia tabla periódica, preferentemente Pt, soportados sobre óxidos de tierras raras, y en particular sobre CeO2, con unas condiciones de reacción para Ia producción de hidrógeno de 400-600 0C y 1-20 bar.Although less widespread, other metal catalysts have also been used for the production of hydrogen from methane. For example, in the patent application JP 07025601, the use of catalysts consisting of elements of group VIII of the periodic table, preferably Pt, supported on rare earth oxides, and in particular on CeO 2 , with reaction conditions is described for the production of hydrogen of 400-600 0 C and 1-20 bar.
El empleo de catalizadores metálicos para Ia generación de hidrógeno mediante Ia descomposición de metano, a pesar de reducir las temperaturas de operación necesarias, presenta como gran inconveniente Ia rápida desactivación que experimentan debido a Ia formación de depósitos de carbono en Ia superficie del catalizador. Asociado a este problema se encuentra el hecho de que su regeneración se lleva a cabo mediante Ia oxidación de los depósitos de carbono, con Ia consecuente formación y emisión de CO2.The use of metal catalysts for the generation of hydrogen by means of methane decomposition, despite reducing the necessary operating temperatures, presents as a great inconvenience the rapid deactivation that they experience due to the formation of carbon deposits on the catalyst surface. Associated with this problem is the fact that their regeneration is carried out through the oxidation of carbon deposits, with the consequent formation and emission of CO 2 .
HOJA DE SUSTITUCIÓN (REGLA 26) La descomposición térmica de metano puede ser catalizada también por materiales de carbono. Esta alternativa está adquiriendo gran interés ya que, aunque los materiales carbonosos suelen presentar menor actividad y requerir temperaturas de reacción más elevadas, existe Ia posibilidad de que las reacciones sean catalíticamente autosostenidas, sin necesidad de realizar etapas de regeneración del catalizador. Asimismo, este proceso puede resultar económicamente ventajoso si el producto carbonoso obtenido es comercializado con un precio adecuado. Esta comercialización o reutilización se ve favorecida por Ia ausencia, en dichos materiales carbonosos, de elementos metálicos contaminantes que, en cambio, están asociados irremediablemente al empleo de catalizadores basados en metales.SUBSTITUTE SHEET (RULE 26) The thermal decomposition of methane can also be catalyzed by carbon materials. This alternative is acquiring great interest since, although the carbonaceous materials usually have less activity and require higher reaction temperatures, there is a possibility that the reactions are catalytically self-sustained, without the need to perform catalyst regeneration steps. Also, this process can be economically advantageous if the carbonaceous product obtained is marketed at an appropriate price. This commercialization or reuse is favored by the absence, in said carbonaceous materials, of contaminating metallic elements that, on the other hand, are irremediably associated with the use of metal-based catalysts.
En este sentido, Ia solicitud de patente WO2000021878 describe un método y dispositivo para Ia producción continua de hidrógeno y carbono mediante pirólisis de metano, gas natural u otros gases de carácter orgánico. El reactor opera bajo un gradiente de temperaturas desde 300 hasta 2000 0C, empleando como catalizador negro de carbono en polvo, que es autoabastecido por el propio sistema de reacción.In this sense, patent application WO2000021878 describes a method and device for the continuous production of hydrogen and carbon by means of pyrolysis of methane, natural gas or other organic gases. The reactor operates under a temperature gradient from 300 to 2000 0 C, using as a black powder carbon catalyst, which is self-supplied by the reaction system itself.
N. Muradov y colaboradores describen el empleo de materiales carbonosos comerciales como catalizadores para Ia descomposición termocatalítica de metano utilizando un reactor de lecho fijo [N. Muradov; F. Smith; A. T-Raiss¡, "Catalytic activity of carbons for methane decomposition reaction", Catal. Today, 2005, 102-103, 225]. En ese trabajo se resumen los resultados obtenidos del empleo de vahos tipos de materiales carbonosos comerciales estudiados para catalizar Ia descomposición de metano, realizando el estudio de Ia actividad catalítica inicial a través de Ia velocidad inicial de reacción. De este estudio se desprende que, en estas condiciones, Ia mayor actividad catalítica inicial Ia presentan carbones activados y negros de humo con elevada superficie específica. El trabajo no presenta estudios de durabilidad de los catalizadores, sin embargo, se pone de manisfiesto Ia rápida desactivación de los carbones activados sometidos a estudio.N. Muradov et al. Describe the use of commercial carbonaceous materials as catalysts for thermocatalytic decomposition of methane using a fixed bed reactor [N. Muradov; F. Smith; A. T-Raiss¡, "Catalytic activity of carbons for methane decomposition reaction", Catal. Today, 2005, 102-103, 225]. This work summarizes the results obtained from the use of many types of commercial carbonaceous materials studied to catalyze the decomposition of methane, carrying out the study of the initial catalytic activity through the initial reaction rate. This study shows that, under these conditions, the higher initial catalytic activity Ia has activated carbon and carbon blacks with a high specific surface area. The work does not present studies on the durability of the catalysts, however, the rapid deactivation of activated carbons under study is manifested.
Continuando en esta línea, otros autores han estudiado Ia actividad catalítica de un grupo de materiales carbonosos específicos en Ia descomposición catalítica de metano. Así, R. Moliner y colaboradores estudiaron Ia actividad catalítica y desactivación de varios carbones activados en un reactor de lecho fijo, obteniendo producciones máximas de 0,7 g de carbono por gramo de catalizador, a 950 0C tras 8 h de reacción [R. Moliner; I. Suelves; MJ. Lázaro; O. Moreno, "Thermocatalytic Decomposition of Methane over Activated Carbons: Influence of Textural PropertiesContinuing along this line, other authors have studied the catalytic activity of a group of specific carbonaceous materials in the catalytic decomposition of methane. Thus, R. Moliner and collaborators studied the catalytic activity and deactivation of several activated carbons in a fixed bed reactor, obtaining maximum productions of 0.7 g of carbon per gram of catalyst, at 950 0 C after 8 h of reaction [R . Moliner; I. You loose; MJ. Lazarus; O. Moreno, "Thermocatalytic Decomposition of Methane over Activated Carbons: Influence of Textural Properties
HOJA DE SUSTITUCIÓN (REGLA 26) and Surface Chemistry"; Int. J. Hydrogen Energy, 2005, 30, 293]. A.M. Dunker y colaboradores han estudiado Ia desactivación de negros de carbono durante Ia descomposición catalítica de metano llevada a cabo en un reactor de lecho fluidizado [A.M. Dunker; S. Kumar; P.A. Mulawa, "Production of hydrogen by thermal decomposition of methane in a fluidized-bed reactor: Effects of catalyst, temperature, and residence time", Int. J. Hydrogen Energy, 2006, 31(4), 473]. El uso de un reactor de lecho fluidizado disminuye Ia desactivación, aumentando Ia cantidad de carbono producido, llegándose a alcanzar 5 g de carbono producido por gramo de catalizador tras 33,3 h de reacción a 925 0C. No obstante, Ia gran mayoría de materiales carbonosos comerciales experimenta una progresiva desactivación como consecuencia del taponamiento de sus microporos por los depósitos del carbono generado que, además, presentan menor actividad que el catalizador inicial.SUBSTITUTE SHEET (RULE 26) and Surface Chemistry "; Int. J. Hydrogen Energy, 2005, 30, 293]. AM Dunker et al. have studied the deactivation of carbon blacks during the catalytic decomposition of methane carried out in a fluidized bed reactor [AM Dunker; S. Kumar; PA Mulawa, "Production of hydrogen by thermal decomposition of methane in a fluidized-bed reactor: Effects of catalyst, temperature, and residence time", Int. J. Hydrogen Energy, 2006, 31 (4), 473] The use of a fluidized bed reactor decreases the deactivation, increasing the amount of carbon produced, reaching 5 g of carbon produced per gram of catalyst after 33.3 h of reaction at 925 0 C. However, the vast majority Commercial carbonaceous materials undergo a progressive deactivation as a result of the clogging of their micropores by the deposits of the generated carbon, which also have less activity than the initial catalyst.
Recientemente se han desarrollado materiales carbonosos mesoporosos ordenados o mesoestructurados mediante diferentes métodos de nano-replicación o nano-moldeo basados en Ia utilización de moldes sólidos inorgánicos (exo- nanomoldeo) u otros compuestos orgánicos en disolución (endo-nanomoldeo), que actúan como agentes directores de Ia mesoestructura carbonosa. Estos materiales se caracterizan por un sistema de poros perfectamente definidos, de geometría y tamaño regular, en el rango de los mesoporos (2-50 nm).Recently, mesoporous or mesostructured carbonaceous materials have been developed by different methods of nano-replication or nano-molding based on the use of inorganic solid molds (exo-molding) or other organic compounds in solution (endo-nanomolding), which act as agents directors of the carbon mesostructure. These materials are characterized by a system of perfectly defined pores, of regular geometry and size, in the range of mesopores (2-50 nm).
La primera síntesis de este tipo de materiales carbonosos basada en el exo- nanomoldeo o nanoreplicación de mesoestructuras sólidas fue publicada por Ryoo y colaboradores, consistente en el empleo de sacarosa como fuente de carbono y sílice mesoporosa MCM-48 como molde inorgánico [R. Ryoo; S. H. Joo; S. Jun, "Synthesis of highly ordered carbón molecular sieves via template-mediated structural transformation", J. Phys. Chem. B, 1999, 103, 7743].The first synthesis of this type of carbonaceous materials based on the exo-molding or nanoreplication of solid mesostructures was published by Ryoo et al., Consisting of the use of sucrose as a source of carbon and MCM-48 mesoporous silica as an inorganic mold [R. Ryoo; S. H. Joo; S. Jun, "Synthesis of highly ordered molecular carbon sieves via template-mediated structural transformation", J. Phys. Chem. B, 1999, 103, 7743].
La síntesis de materiales carbonosos mesoestructurados mediante nanoreplicación de moldes inorgánicos consiste en Ia impregnación de un sólido inorgánico altamente ordenado con un precursor de carbono y Ia posterior polimerización del precursor de carbono a mayor temperatura. Tras someter el conjunto a una etapa de carbonización a elevadas temperaturas bajo atmósfera inerte, el molde inorgánico es eliminado por tratamiento con HF o con una disolución de NaOH, generándose el material carbonoso mesoestructurado correspondiente. Como precursores del carbono se han empleado, entre otros, sacarosa, alcohol furfurílíco, acenafteno y acetileno.The synthesis of mesostructured carbonaceous materials by nanoreplication of inorganic molds consists in the impregnation of a highly ordered inorganic solid with a carbon precursor and the subsequent polymerization of the carbon precursor at a higher temperature. After subjecting the assembly to a carbonization stage at elevated temperatures under an inert atmosphere, the inorganic mold is removed by treatment with HF or with a NaOH solution, generating the corresponding mesostructured carbonaceous material. As precursors of carbon, sucrose, furfuryl alcohol, acenaphthene and acetylene have been used, among others.
HOJA DE SUSTITUCIÓN (REGLA 26) Como molde inorgánico, pueden emplearse silicatos o aluminosilicatos mesoestructurados que posean una estructura de poros interconectados. La polimerización de Ia fuente de carbono es catalizada mediante los centros de Al, en caso de emplearse un aluminosilicato como molde inorgánico, o bien puede añadirse en el medio de impregnación un catalizador apropiado, como el ácido oxálico o ácido sulfúrico. De este modo, se pueden obtener estructuras carbonosas que son negativos del molde inorgánico (CMK-2, a partir de SBA-1 ; CMK-3, a partir de SBA-15; CMK-4, a partir de MCM-48), pueden generarse estructuras de nanotubos por formación de láminas de carbón en el interior de los poros del molde (CMK-5, a partir de SBA-15) e incluso pueden obtenerse otras estructuras por modificaciones en Ia síntesis (CMK-1 , a partir de MCM-48) [R. Ryoo; S. H. Joo; S. Jun, "Ordered mesoporous carbón molecular sieves by templated synthesis: the structural varieties", Stud. Surf. Sci. Catal., 2001 , 135, 1121]. En Ia bibliografía puede encontrarse también estructuras de materiales carbonosos mesoporosos obtenidos a partir de otros moldes silíceos tridimensionales como KIT-5 [A. Vinu; M. Miyahara; V. Sivamurugan; T. Mori; K. Ariga, "Large pore cage type mesoporous carbón, carbón nanocage: a superior adsorbent for biomaterials", J. Mater. Chem., 2005, 15(48), 5122] y KIT-6 [KP. Gierszal; T.-W. Kim; R. Ryoo; M. Jaroniec, "Adsorption and structural properties of ordered mesoporous carbons synthesized by using various carbón precursors and ordered siliceous P6mm and Ia3d mesostructures as templates", J. Phys. Chem. B, 2005, 109(49), 23263].SUBSTITUTE SHEET (RULE 26) As an inorganic mold, mesostructured silicates or aluminosilicates having an interconnected pore structure can be used. The polymerization of the carbon source is catalyzed by the Al centers, if an aluminosilicate is used as an inorganic mold, or an appropriate catalyst, such as oxalic acid or sulfuric acid, can be added to the impregnation medium. Thus, carbonaceous structures that are negative of the inorganic mold (CMK-2, from SBA-1; CMK-3, from SBA-15; CMK-4, from MCM-48) can be obtained, Nanotube structures can be generated by formation of carbon sheets inside the pores of the mold (CMK-5, from SBA-15) and other structures can also be obtained by modifications in the synthesis (CMK-1, from MCM-48) [R. Ryoo; SH Joo; S. Jun, "Ordered mesoporous molecular carbon sieves by templated synthesis: the structural varieties", Stud. Surf. Sci. Catal., 2001, 135, 1121]. In the bibliography, structures of mesoporous carbonaceous materials obtained from other three-dimensional siliceous molds such as KIT-5 [A. Vinu; M. Miyahara; V. Sivamurugan; T. Mori; K. Ariga, "Large pore cage type mesoporous carbon, nanocage carbon: a superior adsorbent for biomaterials", J. Mater. Chem., 2005, 15 (48), 5122] and KIT-6 [KP. Gierszal; T.-W. Kim; R. Ryoo; M. Jaroniec, "Adsorption and structural properties of ordered mesoporous carbons synthesized by using various carbon precursors and ordered siliceous P6mm and Ia3d mesostructures as templates", J. Phys. Chem. B, 2005, 109 (49), 23263].
En cuanto a Ia preparación de materiales carbonosos mesoestructurados por endo-nanomoldeo o endo-nanoreplicación, Ia técnica consiste en realizar Ia polimerización, en disolución, de las moléculas precursoras del carbono en torno a moléculas orgánicas organizadas en forma de entidades supramoleculares o micelas, con las que se ensamblan mediante diferentes mecanismos de interacción. Tras Ia etapa de polimerización se procede a Ia carbonización del material bajo atmósfera inerte, con Ia consecuente eliminación del molde por reacciones de pirólisis. Los precursores de carbono y moldes orgánicos empleados habitualmente son resinas de tipo resol (fenol, resorcinol, formaldehído, etc.) y copolímeros de bloques (Pluronic P- 123, F-127, etc.), respectivamente, pudiéndose obtener materiales carbonosos mesoporosos altamente ordenados con diferentes estructuras y propiedades texturales controladas, en función de las condiciones de síntesis empleadas [CD. Liang; KJ. Hong; G.A. Guiochon; J.W. Mays; S. Dai, "Synthesis of a large-scale highly ordered porous carbón film by self-assembly of block copolymers", Angew. Chem. Int. Ed.,Regarding the preparation of carbonaceous materials mesostructured by endo-nanomolding or endo-nanoreplication, the technique consists in carrying out the polymerization, in solution, of the precursor molecules of carbon around organic molecules organized in the form of supramolecular entities or micelles, with those that are assembled through different interaction mechanisms. After the polymerization stage, the material is carbonized under an inert atmosphere, with the consequent removal of the mold by pyrolysis reactions. The carbon precursors and organic molds commonly used are resins of the resol type (phenol, resorcinol, formaldehyde, etc.) and block copolymers (Pluronic P-123, F-127, etc.), respectively, being able to obtain highly mesoporous carbonaceous materials. ordered with different structures and controlled textural properties, depending on the synthesis conditions used [CD. Liang; KJ Hong; G.A. Guiochon; J.W. Mays; S. Dai, "Synthesis of a large-scale highly ordered porous carbon film by self-assembly of block copolymers", Angew. Chem. Int. Ed.,
HOJA DE SUSTITUCIÓN (REGLA 26) 2004, 43, 5785; F. Zhang; Y. Meng; D. Gu; Y. Yang; C. Yu; B. Tu; D. Zhao, "A facile aqueous route to synthesize highly ordered mesoporous polymers and carbón frameworks with IA3d bicontinuous cubic structure", J. Am. Chem. Soc, 2005, 127, 13508.] Se ha puesto de manifiesto Ia necesidad de encontrar un proceso para Ia obtención de hidrógeno que no sea contaminante y sea ventajosamente económico de tal forma que pueda ser ampliamente utilizado. En este sentido, Ia utilización de materiales de carbono mesoestructurados como catalizadores de Ia descomposición de hidrocarburos ligeros, como el metano, se presenta como Ia alternativa más prometedora siendo a este proceso al que se refiere Ia presente invención. La estructura porosa perfectamente definida y el tamaño de poro medio superior al de los carbones activados confieren a estos catalizadores carbonosos mesoestructurados una actividad muy superior que, además, en determinadas condiciones de operación, muestran una excepcional resistencia a Ia desactivación.SUBSTITUTE SHEET (RULE 26) 2004, 43, 5785; F. Zhang; Y. Meng; D. Gu; Y. Yang; C. Yu; B. You; D. Zhao, "A facile aqueous route to synthesize highly ordered mesoporous polymers and carbon frameworks with IA3d bicontinuous cubic structure", J. Am. Chem. Soc, 2005, 127, 13508.] The need to find a process for obtaining hydrogen that is not polluting and is advantageously economical so that it can be widely used. In this sense, the use of mesostructured carbon materials as catalysts for the decomposition of light hydrocarbons, such as methane, is presented as the most promising alternative being this process to which the present invention refers. The perfectly defined porous structure and the average pore size greater than that of activated carbons give these mesostructured carbonaceous catalysts a much higher activity which, in addition, under certain operating conditions, show exceptional resistance to deactivation.
DESCRIPCIÓN DE LA INVENCIÓNDESCRIPTION OF THE INVENTION
La presente invención se refiere a Ia utilización de materiales carbonosos mesoporosos de elevada superficie específica con distribución regular de poros, en adelante materiales carbonosos mesoestructurados, como catalizadores en Ia producción de hidrógeno. De tal forma que Ia presente invención proporciona un procedimiento con el que se pudo alcanzar producciones de carbono, por descomposición de metano, superiores a 11 veces Ia masa inicial de catalizador carbonoso utilizada, Io que equivale a más de 41 L de hidrógeno producido por cada gramo de catalizador carbonoso utilizado, sin que se aprecie desactivación del catalizador durante el tiempo de reacción y con bajos o nulos contenidos de óxidos de carbono en Ia corriente de salida.The present invention relates to the use of mesoporous carbonaceous materials of high specific surface area with regular distribution of pores, hereinafter mesostructured carbonaceous materials, as catalysts in hydrogen production. In such a way that the present invention provides a process with which carbon productions could be achieved, by methane decomposition, greater than 11 times the initial mass of carbonaceous catalyst used, which is equivalent to more than 41 L of hydrogen produced by each gram of carbonaceous catalyst used, without deactivation of the catalyst during the reaction time and with low or zero carbon oxides content in the output stream.
Así pues, en un primer aspecto, Ia presente invención se refiere a un procedimiento para Ia producción selectiva de hidrógeno mediante descomposición termocatalítica de hidrocarburos ligeros caracterizado porque Ia descomposición de los hidrocarburos está catalizada por un catalizador de material carbonoso mesoestructurado.Thus, in a first aspect, the present invention relates to a process for the selective production of hydrogen by thermocatalytic decomposition of light hydrocarbons characterized in that the decomposition of hydrocarbons is catalyzed by a catalyst of mesostructured carbonaceous material.
En un aspecto más particular, los hidrocarburos ligeros a los que se refiere Ia presente invención comprenden entre 1 y 4 átomos de carbono. En otro aspecto más particular, los hidrocarburos ligeros son lineales. En otro aspecto más particular, losIn a more particular aspect, the light hydrocarbons referred to in the present invention comprise between 1 and 4 carbon atoms. In another more particular aspect, light hydrocarbons are linear. In another more particular aspect, the
HOJA DE SUSTITUCIÓN (REGLA 26) hidrocarburos ligeros son ramificados. En un aspecto preferente, el hidrocarburo de Ia presente invención se refiere al metano.SUBSTITUTE SHEET (RULE 26) Light hydrocarbons are branched. In a preferred aspect, the hydrocarbon of the present invention refers to methane.
En un aspecto particular de Ia presente invención, Ia descomposición termocatalítica de hidrocarburos se realiza a una temperatura comprendida entre 600 - 1400 0C, preferentemente entre 700 - 1150 0C.In a particular aspect of the present invention, the thermocatalytic decomposition of hydrocarbons is carried out at a temperature between 600 - 1400 0 C, preferably between 700 to 1150 0 C.
En un aspecto particular de Ia presente invención, Ia descomposición termocatalítica de hidrocarburos se realiza a una presión de entre 1 - 20 atmósferas, preferentemente se realiza a presión atmosférica.In a particular aspect of the present invention, the thermocatalytic decomposition of hydrocarbons is carried out at a pressure between 1-20 atmospheres, preferably at atmospheric pressure.
La descomposición catalítica de hidrocarburos de Ia presente invención se puede realizar en reactores continuos o semicontinuos del tipo bandeja, de lecho fluidizado, siendo extensiva su aplicación a cualquier reactor tipo gas-sólido.The catalytic decomposition of hydrocarbons of the present invention can be carried out in continuous or semi-continuous reactors of the tray type, fluidized bed, its application being extensive to any gas-solid reactor.
En un aspecto particular de Ia presente invención, el material mesoestructurado tiene una distribución regular de tamaño de poro comprendida entre 2-50 nm.In a particular aspect of the present invention, the mesostructured material has a regular distribution of pore size between 2-50 nm.
En un aspecto particular de Ia presente invención, el material carbonoso mesoestructurado presenta una superficie específica entre 200 y 3000 m2 g"1.In a particular aspect of the present invention, the mesostructured carbonaceous material has a specific surface area between 200 and 3000 m 2 g "1 .
En un aspecto particular de Ia presente invención, el material carbonoso mesoestructurado presenta un volumen de poros comprendido entre 0.5 - 2 cm3g'1 In a particular aspect of the present invention, the mesostructured carbonaceous material has a pore volume comprised between 0.5-2 cm 3 g '1
En un aspecto particular de Ia presente invención, el material carbonoso mesoestructurado presenta un sistema único de poros con una distribución estrecha del tamaño del poro de 30 Á.In a particular aspect of the present invention, the mesostructured carbonaceous material has a unique pore system with a narrow pore size distribution of 30 Á.
En un aspecto particular de Ia presente invención el material carbonoso mesoestructurado presenta un sitema bimodal de poros con un tamaño de los poros de 30 y 50 Á.In a particular aspect of the present invention, the mesostructured carbonaceous material has a bimodal pore system with a pore size of 30 and 50 Á.
En un segundo aspecto, Ia presente invención se refiere a un catalizador caracterizado porque es un material carbonoso mesoestructurado con una distribución regular de tamaños de poro comprendida entre 2-50 nm, una superficie específica entre 200 y 3000 m2 g \ un volumen de poros comprendido entre 0.5 - 2 cm3g"1.In a second aspect, the present invention refers to a catalyst characterized in that it is a mesostructured carbonaceous material with a regular distribution of pore sizes comprised between 2-50 nm, a specific surface area between 200 and 3000 m 2 g \ a pore volume between 0.5 - 2 cm 3 g "1 .
En un aspecto particular, el catalizador de material carbonoso mesoestructurado de Ia presente invención presenta un sistema único de poros con una distribución estrecha del tamaño del poro de 30 Á.In a particular aspect, the mesostructured carbonaceous material catalyst of the present invention has a unique pore system with a narrow pore size distribution of 30 Á.
En un aspecto particular, el catalizador de material carbonoso mesoestructurado de Ia presente invención presenta un sitema bimodal de- poros con un tamaño de los poros de 30 y 50 Á.In a particular aspect, the mesostructured carbonaceous material catalyst of the present invention has a bimodal system of pores with a pore size of 30 and 50 Á.
HOJA DE SUSTITUCIÓN (REGLA 26) En un tercer aspecto, Ia presente invención se refiere al uso del un catalizador de Ia presente invención en Ia producción selectiva de hidrógeno mediante descomposición termocatalítica de hidrocarburos ligeros.SUBSTITUTE SHEET (RULE 26) In a third aspect, the present invention refers to the use of a catalyst of the present invention in the selective production of hydrogen by thermocatalytic decomposition of light hydrocarbons.
DESCRIPCIÓN DE LAS FIGURASDESCRIPTION OF THE FIGURES
La Figura 1 representa Ia comparación de Ia evolución de Ia masa de carbono en función del tiempo, entre el catalizador carbonoso mesoestructurado CM-a y el negro de carbono Black Pearls 2000 (Cabot Corp.), durante Ia reacción de. descomposición termocatalítica de metano a temperatura programada. La Figura 2 recoge Ia comparación de Ia evolución de Ia masa de carbono en función del tiempo, entre el catalizador carbonoso mesoestructurado CM-b y el negro de carbono Black Pearls 2000 (Cabot Corp.), durante Ia reacción de descomposición termocatalítica de metano a temperatura programada.Figure 1 represents the comparison of the evolution of the mass of carbon as a function of time, between the mesostructured carbonaceous catalyst CM-a and the carbon black Black Pearls 2000 (Cabot Corp.), during the reaction of. thermocatalytic decomposition of methane at programmed temperature. Figure 2 shows the comparison of the evolution of the carbon mass as a function of time, between the mesostructured carbonaceous catalyst CM-b and the carbon black Black Pearls 2000 (Cabot Corp.), during the thermocatalytic decomposition reaction of methane a set temperature
La Figura 3 recoge Ia comparación de Ia evolución de Ia masa de carbono producido en función del tiempo, entre el material carbonoso mesoestructurado CM-b y el negro de carbono Black Pearls 2000 (Cabot Corp.), durante Ia reacción de descomposición termocatalítica de metano a temperatura constante de 900 0C.Figure 3 shows the comparison of the evolution of the mass of carbon produced as a function of time, between the mesostructured carbonaceous material CM-b and the carbon black Black Pearls 2000 (Cabot Corp.), during the thermocatalytic decomposition reaction of methane at a constant temperature of 900 0 C.
La Figura 4 recoge Ia comparación de Ia evolución de Ia masa de carbono en función del tiempo de operación, entre el material carbonoso mesoestructurado CM-b y el negro de carbono Black Pearls 2000 (Cabot Corp.), durante Ia reacción de descomposición termocatalítica de metano a temperatura constante de 1000 0C.Figure 4 shows the comparison of the evolution of the carbon mass as a function of the operating time, between the CM-b mesostructured carbonaceous material and the Black Pearls 2000 (Cabot Corp.) carbon black, during the thermocatalytic decomposition reaction of methane at a constant temperature of 1000 0 C.
DESCRIPCIÓN DETALLADA DE LA INVENCIÓNDETAILED DESCRIPTION OF THE INVENTION
La reacción de descomposición termocatalítica de hidrocarburos ligeros utilizando materiales carbonosos mesoestructurados como catalizadores se realiza según procedimientos convencionales en un reactor continuo o semicontinuo del tipo bandeja, de lecho fijo o de lecho fluidizado, siendo extensiva su aplicación a cualquier reactor Gas-Sólido. La reacción puede llevarse a cabo en el intervalo de presiones entre Ia atmosférica y 10 atmósferas, siendo preferible a presión atmosférica. La reacción se lleva a cabo a temperatura programada o en experimentos isotermos, a una temperatura comprendida entre 600 y 1400 0C, preferentemente entre 700 y 1150The thermocatalytic decomposition reaction of light hydrocarbons using mesostructured carbonaceous materials as catalysts is carried out according to conventional procedures in a continuous or semicontinuous reactor of the tray, fixed bed or fluidized bed type, its application being extended to any Gas-Solid reactor. The reaction can be carried out in the pressure range between atmospheric and 10 atmospheres, being preferable at atmospheric pressure. The reaction is carried out at programmed temperature or isothermal experiments, at a temperature between 600 and 1400 0 C, preferably between 700 and 1150
0C. 0 C.
HOJA DE SUSTITUCIÓN (REGLA 26) En el proceso se utilizan hidrocarburos ligeros lineales o ramificados con un número de carbonos comprendido entre 1 y 4, siendo preferible el metano por su mayor contenido relativo de hidrógeno.SUBSTITUTE SHEET (RULE 26) Linear or branched light hydrocarbons with a number of carbons between 1 and 4 are used in the process, methane being preferable because of its higher relative hydrogen content.
La reacción de descomposición termocatalítica de hidrocarburos ligeros utilizando materiales carbonosos mesoestructurados como catalizadores también puede llevarse a cabo en presencia de diluyentes inertes, tales como helio, nitrógeno o argón. En un ejemplo concreto con carácter no limitante, Ia descomposición de metano catalizada por materiales carbonosos mesoestructurados se lleva a cabo con una mezcla comercial de reacción de 10 % de metano en argón. Para Ia producción de hidrógeno, el catalizador carbonoso mesoestructurado se utiliza en forma de partículas de diferentes tamaños. El catalizador se introduce en un reactor provisto de dispositivos para medir Ia temperatura y de un elemento calefactor. En un ejemplo concreto con carácter no limitante, el reactor es un reactor de bandeja de alúmina, en cuyo fondo se sustenta el catalizador conformando un lecho catalítico. Se utiliza un horno eléctrico como elemento calefactor del reactor. El reactor dispone de un termopar para medir Ia temperatura cuyo elemento sensor se encuentra en su base.The thermocatalytic decomposition reaction of light hydrocarbons using mesostructured carbonaceous materials as catalysts can also be carried out in the presence of inert diluents, such as helium, nitrogen or argon. In a specific example with a non-limiting nature, the decomposition of methane catalyzed by mesostructured carbonaceous materials is carried out with a commercial reaction mixture of 10% methane in argon. For the production of hydrogen, the mesostructured carbonaceous catalyst is used in the form of particles of different sizes. The catalyst is introduced into a reactor equipped with devices for measuring the temperature and a heating element. In a specific example with a non-limiting nature, the reactor is an alumina tray reactor, at which bottom the catalyst is supported forming a catalytic bed. An electric oven is used as a heating element of the reactor. The reactor has a thermocouple to measure the temperature whose sensor element is at its base.
Los catalizadores a los que se refiere Ia presente invención son materiales carbonosos mesoporosos ordenados de elevada superficie específica, cuya preparación se detalla a continuación:The catalysts referred to in the present invention are mesoporous carbonaceous materials of high specific surface area, the preparation of which is detailed below:
Material carbonoso mesoestructurado de elevada superficie específica preparado por exo-nanomoldeoMesostructured carbonaceous material of high specific surface prepared by exo-nanomolding
Los materiales carbonosos mesoporosos ordenados o mesoestructurados de elevada superficie específica con diferentes sistemas de poros ordenados se preparan mediante Ia técnica de exo-nanomoldeo según procedimientos recogidos en Ia bibliografía. Un ejemplo no limitante de Ia preparación de un material carbonoso mesoporoso de elevada superficie específica con dos sistemas de poros altamente ordenados se puede encontrar en el método descrito por A.-H. Lu y colaboradores [An- HUÍ LU; Wen-Cui Li; Wolfgang Schmidt; Wolfgang Kiefer; Ferdi Schüth, "Easy synthesis of an ordered mesoporous carbón with a hexagonally packed tubular structure", Carbón , 2004, 42(14), 2939].The ordered mesoporous or mesostructured carbonaceous materials of high specific surface area with different ordered pore systems are prepared by means of the exo-nanomolding technique according to procedures set forth in the literature. A non-limiting example of the preparation of a high-surface mesoporous carbonaceous material with two highly ordered pore systems can be found in the method described by A.-H. Lu et al [An-HUÍ LU; Wen-Cui Li; Wolfgang Schmidt; Wolfgang Kiefer; Ferdi Schüth, "Easy synthesis of an ordered mesoporous carbon with a hexagonally packed tubular structure", Carbon, 2004, 42 (14), 2939].
La preparación de estos materiales carbonosos mesoestructurados comienza con Ia síntesis de un molde inorgánico mesoporoso altamente ordenado, con al menosThe preparation of these mesostructured carbonaceous materials begins with the synthesis of a highly ordered mesoporous inorganic mold, with at least
HOJA DE SUSTITUCIÓN (REGLA 26) dos sistemas de poros distintos e interconectados. Dicho molde inorgánico será determinante en Ia porosidad del material carbonoso final. Un ejemplo no limitante de Ia preparación de un molde inorgánico mesoporoso altamente ordenado se encuentra en Ia preparación del material SBA-15 puramente silíceo detallado por D. Zhao y colaboradores [Dongyuan Zhao, Jianglin Feng, Qisheng Huo, Nicholas Melosh, Glenn H. Fredrickson, Bradley F. Chmelka, Galen D. Stucky, "Triblock Copolymer Syntheses of Mesoporous Silica with Periodic 50 to 300 Angstrom Pores", Science, 1998, 279 (5350), 548].SUBSTITUTE SHEET (RULE 26) two different and interconnected pore systems. Said inorganic mold will be determinant in the porosity of the final carbonaceous material. A non-limiting example of the preparation of a highly ordered mesoporous inorganic mold is found in the preparation of purely siliceous SBA-15 material detailed by D. Zhao et al. [Dongyuan Zhao, Jianglin Feng, Qisheng Huo, Nicholas Melosh, Glenn H. Fredrickson Bradley F. Chmelka, Galen D. Stucky, "Triblock Copolymer Syntheses of Mesoporous Silica with Periodic 50 to 300 Angstrom Pores", Science, 1998, 279 (5350), 548].
Una vez preparado el molde inorgánico mesoestructurado, Ia totalidad de su superficie porosa se cubre de un prepolímero orgánico mediante impregnación, deposición en fase vapor o mediante cualquiera de los métodos existentes para recubrir Ia superficie porosa de un material con otro. Posteriormente, el prepolímero orgánico polimeriza, con el uso o no de temperatura y el uso o no de un catalizador de polimerización, y el polímero, ya formado, se carboniza a elevada temperatura bajo una atmósfera inerte, tal como helio o argón. La última etapa de Ia preparación de los materiales carbonosos mesoporosos altamente ordenados es Ia eliminación del molde inorgánico, mediante uno o varios lavados con algún disolvente que disuelva de manera selectiva el molde inorgánico, tal como una disolución de hidróxido sódico o una disolución de ácido fluorhídrico.Once the mesostructured inorganic mold is prepared, its entire porous surface is covered with an organic prepolymer by impregnation, vapor deposition or by any of the existing methods for coating the porous surface of one material with another. Subsequently, the organic prepolymer polymerizes, with the use or not of temperature and the use or not of a polymerization catalyst, and the polymer, already formed, is carbonized at elevated temperature under an inert atmosphere, such as helium or argon. The last stage of the preparation of highly ordered mesoporous carbonaceous materials is the removal of the inorganic mold, by one or several washes with a solvent that selectively dissolves the inorganic mold, such as a solution of sodium hydroxide or a solution of hydrofluoric acid .
EJEMPLOSEXAMPLES
EJEMPLO 1: Descomposición de metano a temperatura programada catalizada por un material carbonoso mesoestructurado con un único sistema de poros (CM-a), sintetizado mediante exo-nanomoldeo.EXAMPLE 1: Decomposition of methane at programmed temperature catalyzed by a mesostructured carbonaceous material with a single pore system (CM-a), synthesized by exo-nanomolding.
1.a) Preparación del catalizador carbonoso.1.a) Preparation of the carbonaceous catalyst.
Preparación del molde inorgánico SBA-15Preparation of the inorganic mold SBA-15
La preparación del molde inorgánico SBA-15 se basó en el procedimiento descrito por D. Zhao y colaboradores [Dongyuan Zhao, Jianglin Feng, Qisheng Huo, Nicholas Melosh, Glenn H. Fredrickson, Bradley F. Chmelka, Galen D. Stucky, "Triblock Copolymer Syntheses of Mesoporous Silica with Periodic 50 to 300 Angstrom Pores", Science, 1998, 279 (5350), 548]. Se disolvieron 4 gramos de Pluronic P123 en 104 mL de agua y 21 mL de ácido clorhídrico (37 % de riqueza enThe preparation of the inorganic mold SBA-15 was based on the procedure described by D. Zhao et al. [Dongyuan Zhao, Jianglin Feng, Qisheng Huo, Nicholas Melosh, Glenn H. Fredrickson, Bradley F. Chmelka, Galen D. Stucky, "Triblock Copolymer Syntheses of Mesoporous Silica with Periodic 50 to 300 Angstrom Pores ", Science, 1998, 279 (5350), 548]. 4 grams of Pluronic P123 were dissolved in 104 mL of water and 21 mL of hydrochloric acid (37% rich in
HOJA DE SUSTITUCIÓN (REGLA 26) peso) bajo agitación lenta a temperatura ambiente. Posteriormente, se añadieron lentamente 8,5 gramos de tetraetilortosilicato (TEOS), bajo agitación vigorosa y a 40 0C, manteniendo esta temperatura durante 6 horas. El gel obtenido se dejó envejecer a 90 0C y presión autógena durante 3 días. El sólido obtenido se filtró, se secó a 90 °C durante 2 h y se calcinó en aire estático a 550 0C (velocidad de calentamiento de 1 ,8 °C min"1) durante 6 horas.SUBSTITUTE SHEET (RULE 26) weight) under slow stirring at room temperature. Subsequently, they were added slowly 8.5 grams of tetraethylorthosilicate (TEOS), under vigorous stirring and 40 0 C, maintaining this temperature for 6 hours. The gel obtained was aged at 90 0 C and autogenous pressure for 3 days. The solid obtained was filtered, dried at 90 ° C for 2 h and calcined in static air at 550 0 C (heating rate of 1, 8 ° C min "1) for 6 hours.
Preparación del material carbonoso mesoestructurado con un único sistema de poros (CM-a): La preparación del material carbonoso mesoestructurado con un único sistema de poros (CM-a) se realizó de acuerdo al procedimiento descrito por A.-H. Lu y colaboradores [Piotr A. Bazula, An-Hui Lu, Jórg-Joachim Nitz, Ferdi Schüth, "Surface and pore structure modification of ordered mesoporous carbons via a chemical oxidation approach"; Microporous and Mesoporous Materials, 2008, 108(1-3), 266]. Se disolvieron 0,006 gramos de ácido oxálico en 1 ,5 mL de alcohol furfurílico, a temperatura ambiente. La disolución resultante se introdujo, mediante impregnación a humedad incipiente, en los poros de 1 gramo del molde inorgánico SBA-15.Preparation of the mesostructured carbonaceous material with a single pore system (CM-a): The preparation of the mesostructured carbonaceous material with a single pore system (CM-a) was performed according to the procedure described by A.-H. Lu et al [Piotr A. Bazula, An-Hui Lu, Jórg-Joachim Nitz, Ferdi Schüth, "Surface and pore structure modification of ordered mesoporous carbons via a chemical oxidation approach"; Microporous and Mesoporous Materials, 2008, 108 (1-3), 266]. 0.006 grams of oxalic acid were dissolved in 1.5 mL of furfuryl alcohol, at room temperature. The resulting solution was introduced, by impregnation to incipient moisture, into the pores of 1 gram of the inorganic mold SBA-15.
Él sólido impregnado se sometió a tres tratamientos térmicos consecutivos en aire estático: 50 0C durante 12 horas, 70 0C durante 12 horas y 90 0C durante 48 horas más.The impregnated solid was subjected to three consecutive thermal treatments in static air: 50 0 C for 12 hours, 70 0 C for 12 hours and 90 0 C for 48 more hours.
El sólido obtenido se trató, en atmósfera de argón, calentándolo hasta una temperatura de 90 0C a razón de 5 °C min'1, aumentando seguidamente Ia temperatura hasta 150 0C a razón de 1 0C- min"1, y se mantuvo esta temperatura durante 180 minutos. A continuación se aumentó Ia temperatura hasta 300 CC a razón de 1 °C min~1, manteniéndose esta temperatura durante 5 minutos, pasados los cuales se volvió a aumentar Ia temperatura hasta 850 0C a razón de 5 °C min'1, manteniéndose esta temperatura durante 180 minutos, siempre bajo atmósfera de argón.The solid obtained was treated, under argon, heating to a temperature of 90 0 C at 5 ° C min '1, then increasing the temperature to 150 0 C at 1 0 C min "1, and this temperature was maintained for 180 minutes, then the temperature was increased to 300 C at a rate of 1 ° C min ~ 1 , this temperature being maintained for 5 minutes, after which the temperature was increased again to 850 0 C at the rate of 5 ° C min '1 , keeping this temperature for 180 minutes, always under an argon atmosphere.
El molde inorgánico SBA-15 se extrajo con una disolución 1 M de hidróxido sódico compuesta por 3 gramos de hidróxido sódico, 50 mL de agua destilada y 20 mL de etanol absoluto, por cada gramo de SBA-15 a eliminar, manteniendo Ia mezcla a 50 0C durante 24 horas. El material carbonoso mesoestructurado resultante se lavó diez veces con cada uno de los siguientes disolventes: agua destilada, etanol absoluto, ácido nítrico 0,15 M, agua destilada y acetona. El sólido se secó a 90 0C durante 12The inorganic mold SBA-15 was extracted with a 1M solution of sodium hydroxide composed of 3 grams of sodium hydroxide, 50 mL of distilled water and 20 mL of absolute ethanol, for every gram of SBA-15 to be removed, keeping the mixture at 50 0 C for 24 hours. The resulting mesostructured carbonaceous material was washed ten times with each of the following solvents: distilled water, absolute ethanol, 0.15 M nitric acid, distilled water and acetone. The solid was dried at 90 0 C for 12
HOJA DE SUSTITUCIÓN (REGLA 26) horas.SUBSTITUTE SHEET (RULE 26) hours.
El material carbonoso mesoporoso altamente ordenado obtenido de este modo presentó una superficie específica de 1300 m2 g'1, un volumen de poros de 1 ,1 cm3 g"1 y una distribución estrecha de tamaños de poro centrada en torno a 30 amstrong. Este material carbonoso mesoestructurado con un único sistema de poros se identificó como CM-a.The highly ordered mesoporous carbonaceous material obtained in this way had a specific surface area of 1300 m 2 g '1 , a pore volume of 1.1 cm 3 g "1 and a narrow distribution of pore sizes centered around 30 amstrong. This mesostructured carbonaceous material with a single pore system was identified as CM-a.
1.b) Descomposición de metano a temperatura programada catalizada por un material carbonoso mesoestructurado CM-a. El material carbonoso mesoestructurado con un único sistema de poros (CM-a) se disgregó mecánicamente y se tamizó para obtener partículas de catalizador con un tamaño inferior a 0,20 mm. Se tomaron 0,0035 g (3,5 mg) de partículas de catalizador y se colocaron en el centro de un reactor de bandeja de alúmina de 5,4 mm de diámetro interno y 6,8 mm de diámetro externo y 4,0 mm de longitud, cuyo volumen total era de 90 μl. El catalizador se depositó uniformemente en el fondo del reactor de bandeja de alúmina, conformando el lecho catalítico. En Ia base del reactor, se encontraba localizado un termopar para Ia medida de Ia temperatura, cuyo elemento sensor se situaba en el centro de Ia base del reactor de bandeja. Como elemento calefactor del reactor se utilizó un horno eléctrico. El lecho catalítico se trató con un caudal de 100 ml_ (STP) /min [mililitros de gas en condiciones estándar de presión y temperatura (1 atm, 25 0C) por minuto] de nitrógeno puro y elevando Ia temperatura desde Ia ambiente hasta 250 °C en un tiempo total de 12,5 minutos. A continuación, se disminuyó Ia temperatura hasta 50 °C y se cambió Ia alimentación del lecho catalítico por Ia mezcla reactiva metano/argón. La actividad del lecho catalítico fue evaluada alimentando un caudal de 100 ml_ (STP) /min de una mezcla comercial reactiva de 10 % metano / 90 % argón (proporciones volumétricas) y elevando Ia temperatura desde Ia ambiente hasta 1 100 0C en un tiempo total de 105 minutos. Una vez alcanzada Ia temperatura de 1100 0C, ésta se mantuvo durante 45 min. Él seguimiento de Ia evolución de Ia reacción se realizó a través de Ia variación de masa que experimenta el sólido como consecuencia de Ia deposición de carbono, conociendo Ia estequiometría de Ia reacción:1.b) Decomposition of methane at a programmed temperature catalyzed by a CM-a mesostructured carbonaceous material. The mesostructured carbonaceous material with a single pore system (CM-a) was mechanically broken down and screened to obtain catalyst particles smaller than 0.20 mm in size. 0.0035 g (3.5 mg) of catalyst particles were taken and placed in the center of an alumina tray reactor of 5.4 mm internal diameter and 6.8 mm external diameter and 4.0 mm in length, whose total volume was 90 μl. The catalyst was uniformly deposited at the bottom of the alumina tray reactor, forming the catalyst bed. At the base of the reactor, a thermocouple was located for measuring the temperature, whose sensor element was located in the center of the tray reactor base. An electric oven was used as heating element of the reactor. The catalyst bed was treated with a rate of 100 ml_ (STP) / min [milliliters of gas in standard conditions of temperature and pressure (1 atm, 25 0 C) per minute] of pure nitrogen and raising the temperature from the ambient up to 250 ° C in a total time of 12.5 minutes. Then, the temperature was lowered to 50 ° C and the catalyst bed feed was changed to the methane / argon reactive mixture. The activity of the catalytic bed was evaluated by feeding a flow rate of 100 ml_ (STP) / min of a commercial reactive mixture of 10% methane / 90% argon (volumetric proportions) and raising the temperature from the ambient to 1 100 0 C in a time 105 minutes total. Once the temperature of 1100 0 C was reached, it was maintained for 45 min. The follow-up of the evolution of the reaction was carried out through the variation of mass that the solid experiences as a result of the carbon deposition, knowing the stoichiometry of the reaction:
CH4 (gas) + N2 (gas) → 2 H2 (gas) + C (sólido)CH 4 (gas) + N 2 (gas) → 2 H 2 (gas) + C (solid)
HOJA DE SUSTITUCIÓN (REGLA 26) El aumento de masa se debió a Ia producción de carbono, subproducto de Ia reacción. El seguimiento del aumento de peso se realizó mediante termogravimetría , técnica que proporcionaba el rendimiento de carbono asociado al rendimiento de hidrógeno.SUBSTITUTE SHEET (RULE 26) The increase in mass was due to carbon production, a byproduct of the reaction. The weight gain was monitored by thermogravimetry, a technique that provided the carbon yield associated with the hydrogen yield.
Los resultados obtenidos en Ia descomposición termocatalítica de metano a temperatura programada, empleando como catalizador un material carbonoso mesoestructurado con un único sistema de poros (CM-a), se recogen en Ia Tabla 1.The results obtained in the thermocatalytic decomposition of methane at a programmed temperature, using as a catalyst a mesostructured carbonaceous material with a single pore system (CM-a), are shown in Table 1.
Tabla 1. Evolución en función del tiempo de los rendimientos de carbono e hidrógeno obtenidos a temperatura programada con el catalizador CM-a.Table 1. Evolution as a function of the time of the carbon and hydrogen yields obtained at a temperature programmed with the catalyst CM-a.
Figure imgf000016_0001
a) Respecto a Ia masa inicial de catalizador b) Volumen calculado suponiendo comportamiento ideal del H2 (22,4 I-mol"1)
Figure imgf000016_0001
a) Regarding the initial mass of catalyst b) Volume calculated assuming ideal behavior of H 2 (22.4 I-mol "1 )
Para comprobar Ia efectividad del catalizador carbonoso mesoestructurado CM-a en Ia reacción de descomposición termocatalítica de metano a hidrógeno a temperatura programada, se evaluó Ia actividad catalítica de un carbón comercialIn order to verify the effectiveness of the CM-a mesostructured carbonaceous catalyst in the thermocatalytic decomposition reaction of methane to hydrogen at a programmed temperature, the catalytic activity of a commercial coal was evaluated
(negro de carbono Black Pearls 2000 de Ia casa Cabot Corp.), utilizando las mismas condiciones de reacción para poder realizar una comparación de Ia cantidad de carbono y, por Io tanto, de hidrógeno producidos. Se escogió este carbón comercial (negro de carbono Black Pearls 2000 de Cabot Corp.) ya que presenta una superficie específica del mismo orden de magnitud que los materiales carbonosos(Black Pearls 2000 carbon black from the Cabot Corp. house), using the same reaction conditions to be able to make a comparison of the amount of carbon and, therefore, of hydrogen produced. This commercial carbon (Black Pearls 2000 carbon black from Cabot Corp.) was chosen as it has a specific surface area of the same order of magnitude as carbonaceous materials
HOJA DE SUSTITUCIÓN (REGLA 26) mesoestructurados y porque trabajos previos indican que es el catalizador más activo para Ia descomposición termocatalítica de metano de entre muchos materiales carbonosos comerciales. Así, N. Muradov y colaboradores [Nazim Muradov, Franklyn Smith, AIi T-Raissi, "Catalytic activity of carbons for methane decomposition reaction", Catalysis Today (2005), 102-103, 225-233] compararon su actividad con otros veintiún catalizadores basados en materiales carbonosos comerciales, presentando el carbón Black Pearls 2000, de Cabot Corp., Ia mayor actividad catalítica. Estos mismos resultados fueron obtenidos por Alan M. Dunker y colaboradores [Alan M. Dunker, Sudarshan Kumar, Patricia A. Mulawa, "Production of hydrogen by thermal decomposition of methane in a fluidized - bed reactor -Effects of catalyst, temperature, and residence time", International Journal of Hydrogen Energy (2006), 31 (4), 473-484] en un estudio más reducido comparando Ia actividad catalítica del negro de carbono Black Pearls 2000, con otros dos negros de carbono comerciales.SUBSTITUTE SHEET (RULE 26) mesostructured and because previous work indicates that it is the most active catalyst for thermocatalytic decomposition of methane among many commercial carbonaceous materials. Thus, N. Muradov and colleagues [Nazim Muradov, Franklyn Smith, AIi T-Raissi, "Catalytic activity of carbons for methane decomposition reaction", Catalysis Today (2005), 102-103, 225-233] compared their activity with twenty-one others catalysts based on commercial carbonaceous materials, presenting Black Pearls 2000 coal, from Cabot Corp., the greatest catalytic activity. These same results were obtained by Alan M. Dunker and collaborators [Alan M. Dunker, Sudarshan Kumar, Patricia A. Mulawa, "Production of hydrogen by thermal decomposition of methane in a fluidized - bed reactor -Effects of catalyst, temperature, and residence time ", International Journal of Hydrogen Energy (2006), 31 (4), 473-484] in a smaller study comparing the catalytic activity of Black Pearls 2000 carbon black, with two other commercial carbon blacks.
Los resultados obtenidos en Ia descomposición térmica de metano a hidrógeno a temperatura programada, catalizada por un material de carbono comercial (negro de carbono Black Pearls 2000 de Cabot Corp.) utilizando las mismas condiciones de reacción descritas anteriormente, se recogen en Ia Tabla 2.The results obtained in the thermal decomposition of methane to hydrogen at a programmed temperature, catalyzed by a commercial carbon material (Black Pearls 2000 carbon black from Cabot Corp.) using the same reaction conditions described above, are shown in Table 2.
Tabla 2. Evolución en función del tiempo de los rendimientos de carbono e hidrógeno obtenidos a temperatura programada con el carbón comercial (negro de carbono Black Pearls 2000 de Cabot Corp.).Table 2. Evolution as a function of the time of the carbon and hydrogen yields obtained at a programmed temperature with commercial coal (Black Pearls 2000 carbon black from Cabot Corp.).
Figure imgf000017_0001
a) Respecto a Ia masa inicial de catalizador
Figure imgf000017_0001
a) Regarding the initial mass of catalyst
HOJA DE SUSTITUCIÓN (REGLA 26) b) Volumen calculado suponiendo comportamiento ideal del H2 (22,4 I-mol"1).SUBSTITUTE SHEET (RULE 26) b) Volume calculated assuming ideal behavior of H 2 (22.4 I-mol "1 ).
De manera adicional, Ia Figura 1 representa Ia comparación de Ia evolución de Ia masa de carbono en función del tiempo, entre el catalizador carbonoso mesoestructurado CM-a y el negro de carbono Black Pearls 2000 (Cabot Corp.), durante Ia reacción de descomposición termocatalítica de metano a temperatura programada.Additionally, Figure 1 represents the comparison of the evolution of the carbon mass as a function of time, between the mesostructured carbonaceous catalyst CM-a and the carbon black Black Pearls 2000 (Cabot Corp.), during the decomposition reaction thermocatalytic methane at programmed temperature.
EJEMPLO 2: Descomposición de metano a hidrógeno a temperatura programada catalizada por un material carbonoso mesoestructurado con doble sistema de poros (CM-b) sintetizado mediante exo-nanomoldeo.EXAMPLE 2: Decomposition of methane to hydrogen at programmed temperature catalyzed by a mesostructured carbonaceous material with double pore system (CM-b) synthesized by exo-nanomolding.
2.a) Preparación del catalizador carbonoso.2.a) Preparation of the carbonaceous catalyst.
El procedimiento de preparación del material carbonoso mesoestructurado con doble sistema de poros mediante exo-nanomoldeo fue análogo al descrito en el Ejemplo 1 , con Ia salvedad de que Ia impregnación del molde SBA-15 se realizó con una disolución de 0,003 g de ácido oxálico, 0,75 ml_ de alcohol furfurílico y 0,75 ml_ de trimetilbenceno, manteniendo una concentración de alcohol furfurílico en trimetilbenceno del 50 % en volumen y una relación molar de ácido oxálico / alcohol furfurílico de 0,004. De este modo, el material de carbono resultante poseía una estructura porosa altamente ordenada, con una superficie específica de aproximadamente 2000 m2 g"1, un volumen total de poros de 2 cm3 g"1 y una distribución bimodal de tamaños de poro, con tamaños medios de 30 y 50 amstrong, respectivamente.The process of preparing the mesostructured carbonaceous material with double pore system by exo-nanomolding was analogous to that described in Example 1, with the proviso that the impregnation of the SBA-15 mold was carried out with a solution of 0.003 g of oxalic acid, 0.75 ml_ of furfuryl alcohol and 0.75 ml_ of trimethylbenzene, maintaining a concentration of 50% trimethylbenzene furfuryl alcohol in volume and an oxalic acid / furfuryl alcohol molar ratio of 0.004. Thus, the resulting carbon material possessed a highly ordered porous structure, with a specific surface area of approximately 2000 m 2 g "1 , a total pore volume of 2 cm 3 g " 1 and a bimodal distribution of pore sizes, with average sizes of 30 and 50 amstrong, respectively.
2.b) Descomposición de metano a temperatura programada catalizada por un material carbonoso CM-b.2.b) Methane decomposition at programmed temperature catalyzed by a CM-b carbonaceous material.
El procedimiento operativo, condiciones de trabajo y Ia instalación empleada para llevar a cabo Ia descomposición térmica de metano catalizada por el material carbonoso mesoestructurado CM-b fueron idénticos a los empleados en el Ejemplo 1. Igualmente, el seguimiento de Ia evolución de Ia reacción se realizó a través de Ia variación de masa de carbono, medida mediante termogravimetría, y conociendo Ia estequiometría de Ia reacción:The operative procedure, working conditions and the installation used to carry out the thermal decomposition of methane catalyzed by the mesostructured carbonaceous material CM-b were identical to those used in Example 1. Likewise, the follow-up of the evolution of the reaction was made through the variation of carbon mass, measured by thermogravimetry, and knowing the stoichiometry of the reaction:
HOJA DE SUSTITUCIÓN (REGLA 26) CH4 (gas) + N2 (gas) → 2 H2 (gas) + C (sólido)SUBSTITUTE SHEET (RULE 26) CH 4 (gas) + N 2 (gas) → 2 H 2 (gas) + C (solid)
Los resultados obtenidos en Ia descomposición termocatalítica de metano a hidrógeno a temperatura programada utilizando como catalizador el material carbonoso mesoestructurado con doble sistema de poros (CM-b), se recogen en Ia Tabla 3.The results obtained in the thermocatalytic decomposition of methane to hydrogen at a programmed temperature using as a catalyst the mesostructured carbonaceous material with double pore system (CM-b), are shown in Table 3.
Tabla 3. Evolución en función del tiempo de los rendimientos de carbono e hidrógeno obtenidos a temperatura programada con el catalizador CM-b.Table 3. Evolution as a function of the carbon and hydrogen yields obtained at a temperature programmed with the CM-b catalyst.
Figure imgf000019_0001
a) Respecto a Ia masa inicial de catalizador b) Volumen calculado suponiendo comportamiento ideal del H2 (22,4 I-mol"1).
Figure imgf000019_0001
a) Regarding the initial mass of catalyst b) Volume calculated assuming ideal behavior of H 2 (22.4 I-mol "1 ).
HOJA DE SUSTITUCIÓN (REGLA 26) Como en los ejemplos anteriores, Ia efectividad del catalizador carbonoso mesoestructurado con doble sistema de poros (CM-b) en Ia reacción de descomposición térmocatalítica de metano a hidrógeno a temperatura programada, se determinó por comparación con Ia actividad catalítica de un carbón comercial (negro de carbono Black Pearls 2000 de Ia casa Cabot Corp.), utilizando las mismas condiciones de reacción para poder realizar una comparación de las cantidades de carbono e hidrógeno producidas. Los resultados obtenidos en Ia descomposición térmocatalítica de metano a hidrógeno a temperatura programada utilizando negro de carbono comercial (Black Pearls 2000 de Cabot Corp.) como catalizador, utilizando las mismas condiciones de reacción descritas anteriormente, se muestran en Ia Tabla 4. Tabla 4. Evolución en función del tiempo de los rendimientos de carbono e hidrógeno obtenidos a temperatura programada con el carbón comercial (negro de carbono Black Pearls 2000 de Cabot Corp.).SUBSTITUTE SHEET (RULE 26) As in the previous examples, the effectiveness of the mesostructured carbonaceous catalyst with double pore system (CM-b) in the reaction of thermocatalytic decomposition of methane to hydrogen at a programmed temperature, was determined by comparison with the catalytic activity of a commercial carbon (black Carbon Black Pearls 2000 from Cabot Corp.), using the same reaction conditions to be able to make a comparison of the quantities of carbon and hydrogen produced. The results obtained in the thermocatalytic decomposition of methane to hydrogen at a programmed temperature using commercial carbon black (Black Pearls 2000 from Cabot Corp.) as a catalyst, using the same reaction conditions described above, are shown in Table 4. Table 4. Evolution as a function of time of carbon and hydrogen yields obtained at programmed temperature with commercial coal (Black Pearls 2000 carbon black from Cabot Corp.).
Figure imgf000020_0001
a) Respecto a Ia masa inicial de catalizador b) Volumen calculado suponiendo comportamiento ideal del H2 (22,4 I-mol'1).
Figure imgf000020_0001
a) Regarding the initial mass of catalyst b) Volume calculated assuming ideal behavior of H 2 (22.4 I-mol '1 ).
Adicionalmente, Ia Figura 2 recoge Ia comparación de Ia evolución de Ia masa de carbono en función del tiempo, entre el catalizador carbonoso mesoestructuradoAdditionally, Figure 2 shows the comparison of the evolution of the carbon mass as a function of time, between the mesostructured carbonaceous catalyst
HOJA DE SUSTITUCIÓN (REGLA 26) CM-b y el negro de carbono Black Pearls 2000 (Cabot Corp.), que ha sido tomado, de forma análoga al Ejemplo 1 , como catalizador de referencia.SUBSTITUTE SHEET (RULE 26) CM-b and carbon black Black Pearls 2000 (Cabot Corp.), which has been taken, analogously to Example 1, as a reference catalyst.
EJEMPLO 3: Descomposición de metano a hidrógeno a temperatura constante de 900 0C catalizada por un material carbonoso mesoestructurado con doble sistema de poros (CM-b) sintetizado mediante exo-nanomoldeo.EXAMPLE 3 Decomposition of methane to hydrogen at a constant temperature of 900 0 C catalyzed carbonaceous material mesostructured dual pore system (CM-b) synthesized by exo-nanomoldeo.
La síntesis del material carbonoso mesoestructurado CM-b se realizó de acuerdo al procedimiento descrito en el Ejemplo 2. El procedimiento para Ia carga del catalizador en el sistema de reacción, así como Ia instalación de reacción empleada, fueron análogos a los descritos en los ejemplos 1 y 2. Tras las etapas de tratamiento del catalizador con un caudal de 100 ml_ (STP) /min de nitrógeno puro y de calentamiento a 250 0C, se disminuyó Ia temperatura hasta 50 0C, para estabilizar Ia medida, y se volvió a elevar Ia temperatura desde 50 0C hasta 900 0C en un tiempo total de 45 minutos. Una vez se alcanzó Ia temperatura de 900 0C, se cambió Ia alimentación del lecho catalítico por Ia mezcla reactiva de metano/argón. La evaluación de Ia actividad del lecho catalítico realizó alimentando un caudal de 100 mL (STP) /min de una mezcla comercial 10 % metano / 90 % argón (proporciones volumétricas). La temperatura se mantuvo constante a 900 0C durante 170 min.The synthesis of the mesostructured carbonaceous material CM-b was carried out according to the procedure described in Example 2. The procedure for loading the catalyst in the reaction system, as well as the reaction installation employed, were analogous to those described in the examples. 1 and 2. After the catalyst treatment steps with a flow rate of 100 ml_ (STP) / min of pure nitrogen and heating at 250 0 C, the temperature was lowered to 50 0 C, to stabilize the measurement, and became to raise the temperature from 50 0 C to 900 0 C in a total time of 45 minutes. Once the temperature of 900 0 C was reached, the catalytic bed feed was changed by the reactive methane / argon mixture. The evaluation of the activity of the catalytic bed was carried out by feeding a flow rate of 100 mL (STP) / min of a commercial mixture 10% methane / 90% argon (volumetric proportions). The temperature was kept constant at 900 0 C for 170 min.
Al igual que en los ejemplos anteriores, el seguimiento de Ia evolución de Ia reacción se realizó a través de las variaciones de masa de carbono, medidas mediante termogravimetría, y conociendo Ia estequiometría de Ia reacción:As in the previous examples, the monitoring of the evolution of the reaction was carried out through carbon mass variations, measured by thermogravimetry, and knowing the stoichiometry of the reaction:
CH4 (gas) + N2 (gas) → 2 H2 (gas) + C (sólido) Los resultados obtenidos en Ia descomposición termocatalítica de metano a hidrógeno a temperatura constante de 900 0C utilizando como catalizador el material carbonoso mesoestructurado CM-b, se muestran en Ia Tabla 5.CH 4 (gas) + N 2 (gas) → 2 H 2 (gas) + C (solid) The results obtained in the thermocatalytic decomposition of methane to hydrogen at a constant temperature of 900 0 C using as a catalyst the mesostructured carbonaceous material CM- b, are shown in Table 5.
HOJA DE SUSTITUCIÓN (REGLA 26) Tabla 5. Evolución en función del tiempo de los rendimientos de carbono e hidrógeno obtenidos a temperatura constante de 900 0C con el catalizador CM-b.SUBSTITUTE SHEET (RULE 26) Table 5. Evolution over time of the carbon and hydrogen yields obtained at a constant temperature of 900 0 C with the catalyst CM-b.
Figure imgf000022_0001
a) Respecto a Ia masa inicial de catalizador b) Volumen calculado suponiendo comportamiento ideal del H2 (22,4 I-mol"1).
Figure imgf000022_0001
a) Regarding the initial mass of catalyst b) Volume calculated assuming ideal behavior of H 2 (22.4 I-mol "1 ).
Cómo en los ejemplos anteriores, Ia efectividad del catalizador carbonoso mesoestructurado con doble sistema de poros (CM-b) en Ia reacción de descomposición termocatalítica de metano a hidrógeno, a temperatura constante de 900 °C, se determinó por comparación con Ia actividad catalítica de un carbón comercial (negro de carbono Black Pearls 2000 de Ia casa Cabot Corp.), utilizando las mismas condiciones de reacción para poder realizar una comparación de las cantidades de carbono e hidrógeno producidas. Los resultados obtenidos en Ia descomposición térmica de metano a hidrógeno a temperatura constante de 900 0C catalizada por negro de carbono comercial Black Pearls 2000 de Cabot Corp., utilizando las mismas condiciones de reacción descritas anteriormente, se recogen en Ia Tabla 6.As in the previous examples, the effectiveness of the mesostructured carbonaceous catalyst with double pore system (CM-b) in the reaction of thermocatalytic decomposition of methane to hydrogen, at a constant temperature of 900 ° C, was determined by comparison with the catalytic activity of a commercial carbon (Black Pearls 2000 carbon black from the Cabot Corp. house), using the same reaction conditions to be able to make a comparison of the quantities of carbon and hydrogen produced. The results obtained in the thermal decomposition of methane to hydrogen at a constant temperature of 900 0 C catalyzed carbon black commercially Black Pearls 2000 from Cabot Corp., using the same reaction conditions described above are shown in Table 6.
HOJA DE SUSTITUCIÓN (REGLA 26) Tabla 6. Evolución en función del tiempo de los rendimientos de carbono e hidrógeno obtenidos a temperatura constante de 900 0C con un carbón comercial (negro de carbono Black Pearls 2000 de Cabot Corp.).SUBSTITUTE SHEET (RULE 26) Table 6. Evolution vs. time yields of carbon and hydrogen obtained at a constant temperature of 900 0 C with a commercial carbon (carbon black Black Pearls 2000 from Cabot Corp.).
Figure imgf000023_0001
a) Respecto a Ia masa inicial de catalizador b) Volumen calculado suponiendo comportamiento ideal del H2 (22,4 I-mol"1).
Figure imgf000023_0001
a) Regarding the initial mass of catalyst b) Volume calculated assuming ideal behavior of H 2 (22.4 I-mol "1 ).
De manera adicional, Ia Figura 3 recoge Ia comparación de Ia evolución de Ia masa de carbono producido en función del tiempo, entre el material carbonoso mesoestructurado CM-b y el negro de carbono Black Pearls 2000 (Cabot Corp.), durante Ia reacción de descomposición termocatalítica de metano a temperatura constante de 900 0C.Additionally, Figure 3 shows the comparison of the evolution of the mass of carbon produced as a function of time, between the mesostructured carbonaceous material CM-b and the carbon black Black Pearls 2000 (Cabot Corp.), during the reaction of thermocatalytic decomposition of methane at a constant temperature of 900 0 C.
EJEMPLO 4: Descomposición de metano a hidrógeno a temperatura constante de 1000 °C catalizada por un material carbonoso mesoestructurado con doble sistema de poros (CM-b), sintetizado mediante exo-nanomoldeo.EXAMPLE 4: Decomposition of methane to hydrogen at a constant temperature of 1000 ° C catalyzed by a mesostructured carbonaceous material with double pore system (CM-b), synthesized by exo-nanomolding.
La síntesis del material carbonoso mesoestructurado CM-b se realizó de acuerdo al procedimiento descrito en el Ejemplo 2.The synthesis of the mesostructured carbonaceous material CM-b was performed according to the procedure described in Example 2.
El procedimiento para Ia carga del catalizador, así como Ia instalación de reacción empleada, fueron análogos a los descritos en los ejemplos 1 y 2. Tras lasThe procedure for loading the catalyst, as well as the reaction installation used, were analogous to those described in examples 1 and 2. After
HOJA DE SUSTITUCIÓN (REGLA 26) etapas de tratamiento del catalizador con un caudal de 100 ml_ (STP) /min de nitrógeno puro y de calentamiento a 250 "C, se disminuyó Ia temperatura hasta 50 0C, para estabilizar Ia medida, y se volvió a elevar Ia temperatura desde 50 °C hasta 1000 0C en un tiempo total de 50 minutos. Una vez alcanzados los 1000 0C, se cambió Ia alimentación del lecho catalítico por Ia mezcla reactiva de metano/argón. La evaluación de Ia actividad del lecho catalítico se realizó alimentando un caudal de 100 ml_ (STP) /min de una mezcla comercial 10 % metano / 90 % argón (proporciones volumétricas). La temperatura se mantuvo constante a 1000 0C durante un periodo de 280 min.SUBSTITUTE SHEET (RULE 26) Catalyst treatment steps with a flow rate of 100 ml_ (STP) / min of pure nitrogen and heating at 250 "C, the temperature was lowered to 50 0 C, to stabilize the measurement, and the temperature was raised again from 50 ° C up to 1000 0 C in a total time of 50 minutes Once the 1000 0 C was reached, the catalytic bed feeding was changed by the reactive methane / argon mixture The evaluation of the catalytic bed activity was carried out by feeding a flow 100 ml_ (STP) / min of a commercial mixture 10% methanol / 90% argon (volume ratio). The temperature was kept constant at 1000 0 C for a period of 280 min.
Al igual que en los ejemplos anteriores, el seguimiento de Ia evolución de Ia reacción se realizó a través de las variaciones de masa de carbono, medidas mediante termogravimetría, y conociendo Ia estequiometría de Ia reacción:As in the previous examples, the monitoring of the evolution of the reaction was carried out through carbon mass variations, measured by thermogravimetry, and knowing the stoichiometry of the reaction:
CH4 (gas) + N2 (gas) → 2 H2 (gas) + C (sólido)CH 4 (gas) + N 2 (gas) → 2 H 2 (gas) + C (solid)
Los resultados obtenidos en Ia descomposición termocatalítica de metano a hidrógeno a temperatura constante de 1000 0C en presencia del mesoestructurado con doble sistema de poros (CM-b), se recogen en Ia Tabla 7.The results obtained in the thermocatalytic decomposition of methane to hydrogen at a constant temperature of 1000 0 C in the presence of the mesostructured with double pore system (CM-b), are shown in Table 7.
Tabla 7. Evolución en función del tiempo de los rendimientos de carbono e hidrógeno obtenidos a temperatura constante de 1000 0C con el catalizador CM-b.Table 7. Changes with time of yields of carbon and hydrogen obtained at constant temperature of 1000 0 C with the catalyst CM-b.
Figure imgf000024_0001
Figure imgf000024_0001
HOJA DE SUSTITUCIÓN (REGLA 26) a) Respecto a Ia masa inicial de catalizador b) Volumen calculado suponiendo comportamiento ideal del H2 (22,4 I mol"1).SUBSTITUTE SHEET (RULE 26) a) Regarding the initial mass of catalyst b) Volume calculated assuming ideal behavior of H 2 (22.4 I mol "1 ).
Como en los ejemplos anteriores, Ia efectividad del catalizador carbonoso mesoestructurado con doble sistema de poros (CM-b) en Ia reacción de descomposición termocatalítica de metano a hidrógeno a temperatura constante de 1000 0C, se determinó por comparación con Ia actividad catalítica de un carbón comercial (negro de carbono Black Pearls 2000 de Ia casa Cabot Corp.), utilizando las mismas condiciones de reacción para poder realizar una comparación de las cantidades de carbono e hidrógeno producidas. Los resultados obtenidos en Ia descomposición termocatalítica de metano a hidrógeno a temperatura constante de 1000 0C en presencia del negro de carbono comercial Black Pearls 2000 de Cabot Corp. utilizando las mismas condiciones de reacción descritas anteriormente, se recogen en Ia Tabla 8.As in the previous examples, Ia effectiveness of the carbonaceous catalyst mesostructured dual pore system (CM-b) in the reaction thermocatalytic decomposition methane hydrogen at constant temperature of 1000 0 C, was determined by comparing the catalytic activity of a commercial carbon (Black Pearls 2000 carbon black from the Cabot Corp. house), using the same reaction conditions to be able to make a comparison of the quantities of carbon and hydrogen produced. The results obtained in the thermocatalytic decomposition of methane to hydrogen at constant temperature of 1000 0 C in the presence of commercial carbon black Black Pearls 2000 Cabot Corp. using the same reaction conditions described above are shown in Table 8.
Tabla 8. Evolución en función del tiempo de los rendimientos de carbono e hidrógeno obtenidos a temperatura constante de 1000 0C con un carbón comercial (negro de carbono Black Pearls 2000 de Cabot Corp.).Table 8. Evolution as a function of the time of the carbon and hydrogen yields obtained at a constant temperature of 1000 0 C with a commercial carbon (Black Pearls 2000 carbon black from Cabot Corp.).
Figure imgf000025_0001
Figure imgf000025_0001
HOJA DE SUSTITUCIÓN (REGLA 26) a) Respecto a Ia masa inicial de catalizador b) Volumen calculado suponiendo comportamiento ideal del H2 (22,4 I-mol"1).SUBSTITUTE SHEET (RULE 26) a) Regarding the initial mass of catalyst b) Volume calculated assuming ideal behavior of H 2 (22.4 I-mol "1 ).
De manera adicional, Ia Figura 4 recoge Ia comparación de Ia evolución de Ia masa de carbono en función del tiempo de operación, entre el material carbonoso mesoestructurado CM-b y el negro de carbono Black Pearls 2000 (Cabot Corp.), durante Ia reacción de descomposición termocatalítica de metano a temperatura constante de 1000 0C.Additionally, Figure 4 shows the comparison of the evolution of the carbon mass as a function of the operating time, between the CM-b mesostructured carbonaceous material and the Black Pearls 2000 (Cabot Corp.) carbon black, during the reaction thermocatalytic decomposition of methane at a constant temperature of 1000 0 C.
HOJA DE SUSTITUCIÓN (REGLA 26) SUBSTITUTE SHEET (RULE 26)

Claims

REIVINDICACIONES
1. Procedimiento para Ia producción selectiva de hidrógeno mediante descomposición termocatalítica de hidrocarburos ligeros caracterizado porque Ia descomposición termocatalítica de los hidrocarburos está catalizada por un catalizador de material carbonoso mesoestructurado.1. Procedure for the selective production of hydrogen by thermocatalytic decomposition of light hydrocarbons characterized in that the thermocatalytic decomposition of hydrocarbons is catalyzed by a catalyst of mesostructured carbonaceous material.
2. Procedimiento para Ia producción selectiva de hidrógeno mediante descomposición termocatalítica de hidrocarburos ligeros según Ia reivindicación 1 , donde los hidrocarburos ligeros comprenden entre 1 y 4 átomos de carbono.2. Process for the selective production of hydrogen by thermocatalytic decomposition of light hydrocarbons according to claim 1, wherein the light hydrocarbons comprise between 1 and 4 carbon atoms.
3. Procedimiento para Ia producción selectiva de hidrógeno mediante descomposición termocatalítica de hidrocarburos ligeros según cualquiera de las reivindicaciones anteriores, donde los hidrocarburos ligeros son lineales3. Method for the selective production of hydrogen by thermocatalytic decomposition of light hydrocarbons according to any of the preceding claims, wherein the light hydrocarbons are linear
4. Procedimiento para Ia producción selectiva de hidrógeno mediante descomposición termocatalítica de hidrocarburos ligeros según cualquiera de las reivindicaciones anteriores, donde los hidrocarburos ligeros son ramificados4. Process for the selective production of hydrogen by thermocatalytic decomposition of light hydrocarbons according to any of the preceding claims, wherein the light hydrocarbons are branched
5. Procedimiento para Ia producción selectiva de hidrógeno mediante descomposición termocatalítica de hidrocarburos ligeros según cualquiera de las reivindicaciones anteriores, donde Ia descomposición termocatalítica de hidrocarburos se realiza a una temperatura comprendida entre 600 - 1400 0C.5. Process for the selective production of hydrogen by thermocatalytic decomposition of light hydrocarbons according to any of the preceding claims, wherein the thermocatalytic decomposition of hydrocarbons is carried out at a temperature between 600-1400 0 C.
6. Procedimiento para Ia producción selectiva de hidrógeno mediante descomposición termocatalítica de hidrocarburos ligeros según cualquiera de las reivindicaciones anteriores, donde Ia descomposición termocatalítica de hidrocarburos se realiza a una presión de entre 1 - 20 atmósferas.6. Method for the selective production of hydrogen by thermocatalytic decomposition of light hydrocarbons according to any of the preceding claims, wherein the thermocatalytic decomposition of hydrocarbons is carried out at a pressure of between 1-20 atmospheres.
7. Procedimiento para Ia producción selectiva de hidrógeno mediante descomposición termocatalítica de hidrocarburos ligeros según cualquiera de las reivindicaciones anteriores, donde Ia descomposición termocatalítica de hidrocarburos se realiza en un reactor heterogéneo tipo gas-sólido.7. Method for the selective production of hydrogen by thermocatalytic decomposition of light hydrocarbons according to any of the preceding claims, wherein the thermocatalytic decomposition of hydrocarbons is carried out in a heterogeneous gas-solid reactor.
HOJA DE SUSTITUCIÓN (REGLA 26) SUBSTITUTE SHEET (RULE 26)
8. Procedimiento para Ia producción selectiva de hidrógeno mediante descomposición termocatalítica de hidrocarburos ligeros según cualquiera de las reivindicaciones anteriores, donde el catalizador de material carbonoso mesoestructurado tiene una distribución regular de tamaños de poro comprendida entre 2-50 nm.8. Method for the selective production of hydrogen by thermocatalytic decomposition of light hydrocarbons according to any of the preceding claims, wherein the catalyst of mesostructured carbonaceous material has a regular distribution of pore sizes comprised between 2-50 nm.
9. Procedimiento para Ia producción selectiva de hidrógeno mediante descomposición termocatalítica de hidrocarburos ligeros según cualquiera de las reivindicaciones anteriores, donde el catalizador de material carbonoso mesoestructurado presenta una superficie específica entre 200 y 3000 m2 g'1.9. Process for the selective production of hydrogen by thermocatalytic decomposition of light hydrocarbons according to any of the preceding claims, wherein the catalyst of mesostructured carbonaceous material has a specific surface area between 200 and 3000 m 2 g '1 .
10. Procedimiento para Ia producción selectiva de hidrógeno mediante descomposición termocatalítica de hidrocarburos ligeros según cualquiera de las reivindicaciones anteriores, donde el catalizador de material carbonoso mesoestructurado presenta un volumen de poros comprendido entre 0.5 - 2 cm3g"1 10. Process for the selective production of hydrogen by thermocatalytic decomposition of light hydrocarbons according to any of the preceding claims, wherein the catalyst of mesostructured carbonaceous material has a pore volume comprised between 0.5-2 cm 3 g "1
11. Procedimiento para Ia producción selectiva de hidrógeno mediante descomposición termocatalítica de hidrocarburos ligeros según cualquiera de las reivindicaciones anteriores, donde el catalizador de material carbonoso mesoestructurado presenta un sistema único de poros con una distribución estrecha del tamaño del poro de 30 Á.11. Method for the selective production of hydrogen by thermocatalytic decomposition of light hydrocarbons according to any of the preceding claims, wherein the mesostructured carbonaceous catalyst has a unique pore system with a narrow pore size distribution of 30A.
12. Procedimiento para Ia producción selectiva de hidrógeno mediante descomposición termocatalítica de hidrocarburos ligeros según cualquiera de las reivindicaciones anteriores, donde el catalizador de material carbonoso mesoestructurado presenta un sistema bimodal de poros con un tamaño de los poros de 30 y 50 Á.12. Method for the selective production of hydrogen by thermocatalytic decomposition of light hydrocarbons according to any of the preceding claims, wherein the mesostructured carbonaceous catalyst has a bimodal pore system with a pore size of 30 and 50 Á.
13. Catalizador caracterizado porque es un material carbonoso mesoestructurado con una distribución regular de tamaños de poro comprendida entre 2-50 nm, una superficie específica entre 200 y 3000 m2 g"1, un volumen de poros comprendido entre 0.5 - 2 cm3gΛ13. Catalyst characterized in that it is a mesostructured carbonaceous material with a regular distribution of pore sizes between 2-50 nm, a specific surface area between 200 and 3000 m 2 g "1 , a pore volume between 0.5 - 2 cm 3 gΛ
HOJA DE SUSTITUCIÓN (REGLA 26) SUBSTITUTE SHEET (RULE 26)
14. Catalizador según Ia reivindicación 13 caracterizado porque el material carbonoso mesoestructurado presenta un sistema único de poros con una distribución estrecha del tamaño del poro de 30 Á14. Catalyst according to claim 13 characterized in that the mesostructured carbonaceous material has a unique pore system with a narrow pore size distribution of 30 Á
15. Catalizador según Ia reivindicación 13, caracterizado porque el material carbonoso mesoestructurado presenta un sistema bimodal de poros con un tamaño de los poros de 30 y 50 Á.15. Catalyst according to claim 13, characterized in that the mesostructured carbonaceous material has a bimodal pore system with a pore size of 30 and 50 Á.
16. Uso de un catalizador según cualquiera de las reivindicaciones 12-14 en Ia producción selectiva de hidrógeno mediante descomposición termocatalítica de hidrocarburos ligeros.16. Use of a catalyst according to any of claims 12-14 in the selective production of hydrogen by thermocatalytic decomposition of light hydrocarbons.
HOJA DE SUSTITUCIÓN (REGLA 26) SUBSTITUTE SHEET (RULE 26)
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