EP1478459A1 - Catalyseurs d'or sur support d'oxyde metallique, leur procede de production et leur utilisation - Google Patents

Catalyseurs d'or sur support d'oxyde metallique, leur procede de production et leur utilisation

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Publication number
EP1478459A1
EP1478459A1 EP03708030A EP03708030A EP1478459A1 EP 1478459 A1 EP1478459 A1 EP 1478459A1 EP 03708030 A EP03708030 A EP 03708030A EP 03708030 A EP03708030 A EP 03708030A EP 1478459 A1 EP1478459 A1 EP 1478459A1
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Prior art keywords
metal oxide
catalysts
supported
temperatures
clusters
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German (de)
English (en)
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Vojtech Plzak
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    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/50—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification
    • C01B3/56—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification by contacting with solids; Regeneration of used solids
    • C01B3/58—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification by contacting with solids; Regeneration of used solids including a catalytic reaction
    • C01B3/583—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification by contacting with solids; Regeneration of used solids including a catalytic reaction the reaction being the selective oxidation of carbon monoxide
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/48—Silver or gold
    • B01J23/52—Gold
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    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/66—Silver or gold
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    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/89—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/20—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state
    • B01J35/23—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state in a colloidal state
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • 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
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B01J35/391—Physical properties of the active metal ingredient
    • B01J35/393—Metal or metal oxide crystallite size
    • 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
    • B01J35/613—10-100 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
    • B01J35/64—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
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0201—Impregnation
    • 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
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/03—Precipitation; Co-precipitation
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    • 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
    • C01B3/06—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of inorganic compounds containing electro-positively bound hydrogen, e.g. water, acids, bases, ammonia, with inorganic reducing agents
    • C01B3/12—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of inorganic compounds containing electro-positively bound hydrogen, e.g. water, acids, bases, ammonia, with inorganic reducing agents by reaction of water vapour with carbon monoxide
    • C01B3/16—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of inorganic compounds containing electro-positively bound hydrogen, e.g. water, acids, bases, ammonia, with inorganic reducing agents by reaction of water vapour with carbon monoxide using catalysts
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/15—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively
    • C07C29/151—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively with hydrogen or hydrogen-containing gases
    • C07C29/1516—Multisteps
    • C07C29/1518—Multisteps one step being the formation of initial mixture of carbon oxides and hydrogen for synthesis
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    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/02—Processes for making hydrogen or synthesis gas
    • C01B2203/0283—Processes for making hydrogen or synthesis gas containing a CO-shift step, i.e. a water gas shift step
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/04—Integrated processes for the production of hydrogen or synthesis gas containing a purification step for the hydrogen or the synthesis gas
    • C01B2203/0435—Catalytic purification
    • C01B2203/044—Selective oxidation of carbon monoxide
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
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    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/04—Integrated processes for the production of hydrogen or synthesis gas containing a purification step for the hydrogen or the synthesis gas
    • C01B2203/0465—Composition of the impurity
    • C01B2203/047—Composition of the impurity the impurity being carbon monoxide
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/06—Integration with other chemical processes
    • C01B2203/066—Integration with other chemical processes with fuel cells
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/10—Catalysts for performing the hydrogen forming reactions
    • C01B2203/1041—Composition of the catalyst
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/06—Combination of fuel cells with means for production of reactants or for treatment of residues
    • H01M8/0606—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants
    • H01M8/0612—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants from carbon-containing material
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to metal oxide-supported Au catalysts with a narrow Au cluster size distribution and high degree of dispersion of the Au clusters, a process for their preparation and their use, in particular for selective CO oxidation in reformer gases (PROX) and in low-temperature water gas conversion ( WGS).
  • PROX reformer gases
  • WGS low-temperature water gas conversion
  • oxide-supported Au catalysts whose Au clusters have a diameter of less than about 5 nm, which corresponds to a degree of dispersion of ⁇ 20%.
  • the choice of the oxidic carrier plays an important role especially in those reactions where oxygen species influence the reaction, either directly (oxidation with 0 2 ) or indirectly (as with WGS).
  • easily reducible oxide supports such as Fe 2 ⁇ 3 (Fe 3 ⁇ 4 ), Co 3 0, Ni 2 ⁇ 3 (NiO), Mn 3 0 or Ti0 2 , which promote the transport of activated oxygen the gold Accelerating cluster control has also been recognized in various reactions.
  • metal oxide supported Au catalysts Au / MeO x .
  • CP coprecipitation
  • water-soluble metal salts and a water-soluble Au compound usually HAuCl
  • a base in an aqueous medium the precipitate formed is dried and subjected to calcination in air at temperatures of usually 300 to 400 ° C.
  • deposition precipitation also referred to as “deposition precipitation” or “DP”
  • the carrier component is first deposited in the same way as in the case of CP catalysts, but without the addition of a gold compound. Rather, the gold is deposited on the precalcined metal oxide support.
  • powdered metal oxides are suspended in water and reacted with a water-soluble Au compound in an aqueous medium with a base. This is also followed by calcination in air at usually 300 to 400 ° C.
  • Hyperßne Interacttons 126 (2000) 95-99 describes investigations of nano-sized Au catalysts supported on Mg (OH) 2 and Ti0 2 using 197 Au-Mössbauer spectroscopy. The catalyst samples were prepared by precipitation precipitation and calcination in air at 473-573 K for 4 hours. From this work it can be concluded that Au (+) presumably shows a higher catalytic activity for the oxidation of CO than Au (0).
  • Catalysts Letters Vol. 77, No. 1 -3 (2001) 87-95 describes activity studies of nano-sized Au / CeO 2 catalysts for the low-temperature - water gas conversion. It is concluded that the activity strongly depends on the presence of nano-sized CeO 2 particles.
  • the catalyst samples were produced by coprecipitation, deposition coprecipitation or gelation / coprecipitation with subsequent calcination in air at 400 ° C., 650 ° C. or 800 ° C.
  • the gold particles in the CP catalysts had an average size of 8 nm, while the gold particles in the DP catalysts had a size of at least 4.5 nm.
  • the coprecipitation method leads to relatively large Au clusters in all cases in which a metal oxide carrier precursor salt which can be easily oxidized by Au (3+) is used, such as the nitrates of cobalt, manganese and cerium or the salts of divalent iron.
  • a metal oxide carrier precursor salt which can be easily oxidized by Au (3+) is used, such as the nitrates of cobalt, manganese and cerium or the salts of divalent iron.
  • Evidence of the light Au coagulation in an aqueous suspension can be provided by subsequent reduction of the Au complex deposited on a support or precursor with selectively acting H 2 O 2 .
  • the present invention is based on the object of providing metal oxide-supported Au catalysts with increased activity and selectivity, in particular for PROX and WGS applications at low temperature, and sufficient long-term stability, and a process for their preparation.
  • the invention accordingly relates to metal oxide-supported Au catalysts with a narrow Au cluster size distribution and a high degree of dispersion of the Au clusters, obtainable by drying and drying moist Au / metal oxide catalyst precursors obtained in a known manner by coprecipitation, deposition precipitation or impregnation reduced the dried precursors in the gas phase with H 2 or CO at temperatures of ⁇ 250 ° C.
  • the invention further relates to a method for producing such
  • Au catalysts in which the moist Au / metal oxide catalyst precursors obtained in a known manner are dried by coprecipitation, deposition precipitation or impregnation and the dried precursors in the gas phase with H 2 or CO at temperatures of ⁇ 250 ° C reduced.
  • the invention also relates to the use of the Au catalysts described above for selective CO oxidation in reformer gases (PROX), in low-temperature water gas conversion (WGS), in methanol synthesis, for epoxidation of olefins or for the total oxidation of CO, hydrocarbons or halogenated gases (VOC).
  • PROX reformer gases
  • WGS low-temperature water gas conversion
  • VOC halogenated gases
  • the invention it has surprisingly been found that it is possible to fix Au clusters in crystallite sizes on the surfaces of the metal oxide supports that are at least about 0.5 nm smaller in diameter than those after the usual calcination in air at 300 to 400 ° C obtained when the pre-dried Au 2 ⁇ 3 / MeO x catalyst precursor with H 2 or CO at temperatures of ⁇ 250 ° C under a reduction treatment.
  • the reduction of an Au / TiO 2 catalyst precursor with a relatively high Au loading of 4.5% by weight with H 2 at 200 ° C. leads to Au nanoclusters with a diameter of approximately 1.7 nm, whereas the calcination of this catalyst precursor at 400 ° C.
  • the Au cluster size distribution for the Au catalysts according to the invention is much narrower ( ⁇ 0.5 nm) than for the catalysts conventionally produced by calcination ( ⁇ 0.9 nm). Accordingly, the catalysts according to the invention have an increased degree of dispersion of the Au clusters of at least approximately 55%, compared to approximately 32% for Au catalysts calcined in a conventional manner. This means that the Au catalysts according to the invention have a catalytic activity which is increased by almost a factor of 2, as can be demonstrated with the PROX reaction at 80 ° C.
  • FIG. 1 shows the melting limit of nano-Au surfaces as a function of the temperature and the Diameter (XRD, TEM) of Au (4.5% by weight) / TiO 2 catalysts after reduction with H 2 at different temperatures. It is known from previous studies that Au particles in the nano-size range of less than about 5 nm begin to melt on the surface well below the melting temperature of solid gold (1064 ° C), and that the melting limit decreases as the Au clusters become smaller , If one or more other Au nanoclusters are in the immediate vicinity of a superficially melting Au cluster, these (Ostwald ripening) coagulate to form larger particles.
  • the full squares in Figure 1 represent the mean values of the Au diameters of the gold reflections [111] and [200] obtained from XRD difference spectra.
  • the circular symbols (full: XRD; empty: TEM) stand for the reference samples calcined in air. It can be seen from FIG. 1 that if the temperature during the reduction treatment in the gas phase does not exceed 250 ° C., the Au clusters remain unmelted and in a size range below 2 nm or even around 1.6 nm ( Reduction temperature at 100 ° C).
  • the metal oxide is preferably selected from the group consisting of Fe 2 0 3 , Ti0 2 , A1 2 0 3 , Ce0 2 , Ce (Zr) 0 2 , Si0 2 , Zr0 2 , Co 3 0 4 , NiO, MnO x and Fe 2 0 3 - ⁇ -Al 2 0 3 .
  • the gas phase reduction is preferably carried out at temperatures at which at most the outer oxide layers are reduced, ie at temperatures of ⁇ 140 ° C.
  • the reduction treatment is preferably carried out at temperatures of 80 80 ° C.
  • the Au loading of the catalysts according to the invention can be in a wide range and is preferably 0.5-8% by weight of Au, more preferably 2-5% by weight of Au.
  • the catalysts according to the invention have the highest possible specific surface area, preferably of at least about 20 m 2 / g, more preferably at least about 50 m 2 / g according to the BET method.
  • the Au clusters in the catalysts according to the invention have the highest possible degree of dispersion, so that the Au clusters preferably have a diameter of less than about 6 nm, more preferably less than about 4 nm, most preferably 1 -3 nm ,
  • a high specific surface area and a high degree of dispersion of the Au clusters are particularly advantageous from a kinetic point of view, since the step determining the reaction rate takes place at the gold-metal oxide interface in CO oxidation. Therefore, with the same Au coating, the degree of dispersion of the gold is very important with regard to the CO conversion rate.
  • calcination in air is carried out according to the invention at temperatures of at least about 300 ° C., preferably 300 to 400 ° C., after the reduction treatment. It has been shown that such a subsequent calcination results in only a relatively small enlargement of the Au clusters (see also diamonds in FIG. 1; full: XRD; empty: TEM). This applies not only to the Au / Ti ⁇ 2 catalysts according to the invention, but also to the other systems, such as Au / F ⁇ 2 ⁇ 3 and Au / C ⁇ 3 ⁇ 4 .
  • the increased catalytic activity of the catalysts according to the invention is of particular relevance also for technical processes which take place at temperatures higher than 200 ° C., such as the (CO + H 2 ) reactions, the selective oxidation of propene to propylene oxide (for example with Au / Ti ⁇ 2 ) or the oxidative removal of organic trace gases from the exhaust air (for example with AU / C0 3 O 4 ).
  • the Au catalysts according to the invention are generally suitable for selective CO oxidation in reformer gases (PROX), for low-temperature water gas conversion (WGS), for methanol synthesis, for the epoxidation of olefins or for the total oxidation of CO, hydrocarbons or halogenated hydrocarbons (VOC).
  • the catalysts according to the invention are used for selective low-temperature CO oxidation in reformate hydrogen for PEM fuel cells or for low-temperature water gas conversion (WGS), in particular at temperatures of 150 150 ° C.
  • an Au / CeO 2 catalyst was found to be particularly active, in which the Au precursor (AU 2 O 3 ) was applied to a commercial cerium dioxide powder with a high specific surface area and the dried catalyst precursor was reduced with hydrogen according to the invention.
  • the Au precursor AU 2 O 3
  • CeO 2 supports no full reduction of the trivalent gold to the metal as with the Au / TiO 2 system in TGA experiments and subsequent XRD measurements ( no Au (O) reflex) could be detected.
  • the PROX reaction in the idealized format (1.0% CO, 1.0% 0 2 , 75% H 2 , rest N 2 ) served as a test for the catalytic activity at 80 ° C. in a microreactor under differential reaction conditions ( Weigh the pulverized catalysts after dilution with C1-Al 2 O 3 , 50 to 100 mg, gas flow 50 to 100 Nml / min.).
  • the measured reaction rates (normalized to the gold mass) are summarized in Table 1 below together with some physical data determined using XRD, TEM, ICP-Au analysis and BET.
  • Example 8 shows, a uniform pre-impregnation of the porous matrix with the ferrihydrite precursor does not succeed, so that when Au is subsequently coated, a large part of the Au clusters is fixed to the catalytically far inactive A. 2 ⁇ 3 surface, which leads to a reduction in overall activity.
  • Examples 9 and 10 show that the porous pellets are uniformly coated with the oxidic active component via molten salt and calcination, and that in the end result the subsequent Au impregnation on the relatively low-surface active oxide ( ⁇ -Fe 2 ⁇ 3 ) is comparable Activity leads when the precursor is reduced after the treatment described in this invention under mild conditions in the gas phase (Example 11).
  • Such or another type of pre-fixation (impregnation and precalcination) of an oxidic active component within a porous matrix is also state of the art for other oxide matrix composites (such as Ce (Zr) 0 2 -Al ⁇ 3 or Ti0 -Si0 2 ) , Example 1: Au / Ti0 2 (Au impregnation, calcined)
  • Example 1 The first procedure is as described in Example 1, except that an approximately 10% hydrogen peroxide solution at RT is added to the suspension before the last filtration, which quickly turns blue.
  • the XRD shows clear Au reflections, from the width of which a gold crystallite size of 14.5 nm can be determined using the Scherr equation. This does not change even after calcinations below 400 ° C.
  • the result of the kinetic measurements shows, in accordance with the lower Au dispersion, a significantly lower rate than with the reference according to Example 1.
  • Example 3 Au / Ti0 2 (Au impregnation, reduced with H 2 ); inventively
  • the powder according to Example 1 is brought to 200 ° C. under N 2 after drying and, after a holding time of about 1/2 h at this temperature, is treated with 10% H 2 in N 2 for half an hour.
  • the XRD difference spectra of this catalyst show very broad Au [III] and Au [200] reflections whose evaluation (Scherr equation) leads to a mean d (Au) of 1.8 nm. From TEM images (2500 clusters counted), the mean geometric diameter of the Au clusters is also 1.8 nm. The size distribution is very narrow at ⁇ 0.5 nm. According to the high Au dispersion of this preparation, its activity is very high; about twice as high as that of the calcined reference according to Example 1.
  • the Au / Co 3 0 4 catalyst thus obtained shows a very weak activity, largely due to the fact that the Au dispersion is very low (d (Au) ⁇ 9 nm). In analogy to example 2, this is due to the slight agglomeration of the metallic gold, which is formed during the precipitation by the in situ reduction of the Au (3 +) complex by the easily oxidizable divalent cobalt ion.
  • Example 4 The precipitation according to Example 4 is repeated, but without the addition of a gold compound. After drying, it is calcined at 400 ° C. for 2 hours. The cobalt spinel obtained (3.0 g) is then dispersed in 300 ml of water and warmed to 60 ° C. The coating with 6 ml of 0.14 M gold chloride solution with buffering with a sodium carbonate solution (pH between 7.0 and 7.5) and further operations are then carried out in the same way as shown in Example 1. Finally, the dried powder is calcined for 1/2 h at 400 ° C.
  • Example 6 Au / Co 3 0 4 (Au impregnation, reduced with H 2 at 70 ° C, post-calcined at 300 ° C); inventively
  • Example 5 is repeated, but with the difference that after predrying under vacuum, post-drying is first (mandatory) approx. 200 ° C in air. The mixture is then cooled to 70 ° C. and, after flushing with nitrogen, the sample is treated with 10% H 2 in N 2 for two hours. Subsequent calcination (mandatory for applications at higher temperatures, see below) for 1/2 hour in air at 300 ° C. The initial activity of the Au / Co 3 0 4 - treated dry-reductively in this way -
  • Catalyst is significantly higher than that of the only calcined reference according to Example 5. Both this catalyst and that according to Example 5 are less suitable for the PROX reaction, since both deactivate rapidly due to the strong formation of carbonate. On the other hand, very high activity is expected for applications in oxidizing atmospheres in the field of environmental chemistry, such as for the elimination of HC from air.
  • Example 7 Au / Fe 2 0 3 (Au deposition-precipitation on ferrihydrite, calcined)
  • Example 8 Au / Fe 2 0 3 - ⁇ -Al 2 0 3 (deposition-precipitation by "deposition-precipitation” on ferrihydrite fixed by neutralization in pellets, calcined)
  • the pellets After the pellets have been separated from the remaining suspension, they are immersed in 0.5 l of water and annealed at 80 ° C. for 1/2 hour. This is followed by impregnation at 60 ° C with a HAuCl 4 solution (4.04 g HAuCl 4 * 3H 2 0 in 10 ml water) within approx. 4 min. with stirring while buffering with soda (pH: 6.3 to 7.3). The mixture is stirred for about 3 hours until the pH is constant. After cooling, the pellets are rinsed overnight with deionized water, then approx. Dried at 80 ° C for 10 hours and finally calcined at 400 ° C (1/2 h). A small part of the dark brown catalyst is pulverized for kinetic measurements.
  • the activity of the powdered sample is only approx. 20% of the activity of the analog powder catalyst according to Example 7 is reached.
  • this is due to an uneven distribution of the hematite within the pellets: while the gold is evenly distributed throughout, the center and the outer regions of the pellet rings remain free of the active oxide hematite.
  • Example 9 Au / Fe 2 0 3 - ⁇ -Al 2 0 3 (via Fe nitrate melt, Au impregnation, calcined)
  • Example 10 Au / Fe 2 0 3 - ⁇ -Al 2 0 3 (via Fe nitrate melt, Au impregnation, reduced at 120 ° C); inventively
  • the final calcination is dispensed with and the pellets prepared according to Example 9 are dried in air at 200 ° C. After cooling to 120 ° C. and intermediate rinsing with N 2 , the pellets are reduced with 10% H 2 in N 2 for half an hour.
  • the activity (measured on the pulverized product) is also higher here than that of the catalyst conventionally conditioned in air at 300 to 400 ° C. according to Example 9.
  • the Au clusters cannot be measured to a large extent.
  • Example 11 Au / Ce0 2 (Au impregnation on coarsely crystalline support, calcined)
  • Example 12 Au / Ce0 2 (Au impregnation on coarsely crystalline support, with 5 ml of a 0.09 M HAuCl 4 solution with simultaneous buffering with a soda solution at pH values between 6.5 and 7.0 offset. After the usual further processing and drying (RT under vacuum), this Au / Ce0 2 catalyst precursor is calcined in air for 1/2 hour. It can be seen from Table 1 that the Au crystallites are relatively large and their size distribution is relatively broad. As already explained above, this should be due to the easy mobility and the confluence of melted gold ponds on the relatively "smooth" oxide surface during and after the thermal Au 2 0 3 decomposition above approx. 350 ° C. The activity of this catalyst is rather modest due to the low Au dispersion.
  • Example 12 Au / Ce0 2 (Au impregnation on coarsely crystalline support, with 5 ml of a 0.09 M HAuCl 4 solution with simultaneous buffering with a soda solution at pH values between 6.5 and 7.0 offset.
  • Example 11 The procedure here is as in Example 1 1, but with the difference that the Au / Ce0 2 precursor is reduced with hydrogen after drying at 200 ° C. for 3/4 h and then at the same temperature with 5% 0 2 is oxidized again in N 2 and then with air to stabilize the cerium oxide carrier. In this way it is also possible to stabilize very small Au clusters on the carrier, which also shows the higher activity in comparison to example 11.
  • Examples 11 and, above all, 12 also demonstrate that controlled Au impregnation can be used to deposit very small Au clusters ( ⁇ 5 nm) even on coarsely crystalline oxide supports ( ⁇ 50 m 2 / g).
  • Example 14 Au / Ce (Zr) 0 2 (Au impregnation, reduced with HJ; according to the invention
  • Example 12 the only dried catalyst precursor according to Example 13 is reduced in a hydrogen stream at 200 ° C. and then oxidized again.
  • the activity measured afterwards is now approx. 70% above that of the conventionally calcined powder at 400 ° C of the previous example.
  • No Au reflex can be made visible in the XRD, which means that here either amorphous Au (d (Au) ⁇ approx. 1.5 nm) or the gold in univalent state (Au (+)), which is stabilized by the tetravalent cerium (see below).
  • Example 15 Au / Ce0 2 (Au impregnation, reduced with H ⁇ ; according to the invention
  • a Difficult to determine due to the superposition of the Au and oxide reflections; b: no or weak Au reflections; c: no or poor contrast due to amorphous Au and / or amorphous oxide carrier

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Abstract

L'invention concerne des catalyseurs d'or sur support d'oxyde métallique, ayant une répartition de dimension d'agglomérats d'or plus étroite et un degré de dispersion élevé des agglomérats d'or. On obtient ces catalyseurs d'or en séchant des précurseurs de catalyseurs or/oxyde métallique humides obtenus de manière connue par coprécipitation, précipitation séparée ou imprégnation et en réduisant les précurseurs séchés dans la phase gazeuse avec H2 ou CO à des températures inférieures ou égales à 250 °C. Les catalyseurs selon l'invention conviennent à l'oxydation CO sélective dans des gaz reformeurs (PROX), à la conversion du gaz à l'eau à basse température (WGS), à la synthèse du méthanol, à l'époxydation d'oléfines ou à l'oxydation totale de CO, d'hydrocarbures ou de gaz halogénés (VOC).
EP03708030A 2002-02-13 2003-02-13 Catalyseurs d'or sur support d'oxyde metallique, leur procede de production et leur utilisation Withdrawn EP1478459A1 (fr)

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DE10205873A DE10205873A1 (de) 2002-02-13 2002-02-13 Metalloxidgeträgerte Au-Katalysatoren, Verfahren zu deren Herstellung sowie deren Verwendung
DE10205873 2002-02-13
PCT/DE2003/000439 WO2003068389A1 (fr) 2002-02-13 2003-02-13 Catalyseurs d'or sur support d'oxyde metallique, leur procede de production et leur utilisation

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CN104353456A (zh) * 2014-11-14 2015-02-18 上海应用技术学院 一种负载金的二氧化钛纳米催化剂及其制备方法和应用
CN107115861A (zh) * 2017-05-16 2017-09-01 嘉兴学院 一种Au‑TiO2‑x催化剂及其应用

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US7169376B2 (en) 2004-06-10 2007-01-30 Chevron U.S.A. Inc. Method for making hydrogen using a gold containing water-gas shift catalyst
GB0405382D0 (en) * 2004-03-10 2004-04-21 Johnson Matthey Plc Water gas shift catalyst
ES2261080B1 (es) * 2005-04-19 2007-12-16 Universidad Politecnica De Valencia Procedimiento y catalizadores para la expoxidacion de compuestos olefinicos en presencia de oxigeno.
DE102005036890A1 (de) 2005-08-05 2007-02-08 Südzucker AG Mannheim/Ochsenfurt Geträgerter Goldkatalysator
CN101421878B (zh) * 2006-02-15 2011-06-15 3M创新有限公司 使用催化活性金时相对于氢气而言对一氧化碳的选择性氧化
CN103191737B (zh) * 2013-03-11 2015-01-14 浙江大学 降解挥发性有机物的负载型纳米Au-CeO2催化剂及其制备方法
FR3033268B1 (fr) * 2015-03-05 2019-08-16 IFP Energies Nouvelles Catalyseur comprenant de l'or disperse de maniere homogene dans un support poreux
CN105344383B (zh) * 2015-12-11 2018-07-20 中国科学院上海高等研究院 一种载体TiO2及其制备方法与应用
CN108816226B (zh) * 2018-05-22 2021-09-24 内蒙古工业大学 一种用于5-羟甲基糠醛氧化合成2,5-呋喃二甲酸的负载型金催化剂的制备和应用

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CN104353456A (zh) * 2014-11-14 2015-02-18 上海应用技术学院 一种负载金的二氧化钛纳米催化剂及其制备方法和应用
CN107115861A (zh) * 2017-05-16 2017-09-01 嘉兴学院 一种Au‑TiO2‑x催化剂及其应用

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