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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
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/02—Impregnation, coating or precipitation
  • B01J37/0215—Coating
  • B01J37/0217—Pretreatment of the substrate before coating
• • 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
• • 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
  • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
  • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
  • B01J23/32—Manganese, technetium or rhenium
  • B01J23/36—Rhenium
• • 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
  • 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
• • 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
  • 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
  • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
  • B01J23/44—Palladium
• • 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
  • 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
  • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
  • B01J23/46—Ruthenium, rhodium, osmium or iridium
  • B01J23/462—Ruthenium
• • 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
  • 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
• • 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
  • B01J37/0215—Coating
  • B01J37/0221—Coating of particles
  • B01J37/0223—Coating of particles by rotation
• • 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
  • B01J37/0238—Impregnation, coating or precipitation via the gaseous phase-sublimation
• • 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
  • B01J37/04—Mixing
• • 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
• • 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
  • B01J35/396—Distribution of the active metal ingredient
  • B01J35/397—Egg shell like
• • 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

Definitions

• the invention relates to a process for the preparation of coated catalysts which contain at least one catalytically active metal on an inorganic or carbon support.
• Shell catalysts can be obtained by various methods. For example, inorganic supports can be impregnated with a metal salt solution of the catalytically active metal, which can be followed by a drying and reduction step. In particular with shell catalysts which contain ruthenium on silicon dioxide, it is difficult to obtain sharp shell profiles using the classic Tr ink process. However, a distinctive shell profile offers advantages with regard to the internal mass transfer when using the catalyst and thus allows the production of generally more active and selective fixed bed catalysts.
• the activity of the catalyst generally drops sharply when the catalyst is reused in a second application attempt. After the second try, however, the activity stabilizes. This behavior can be attributed to the initial detachment of Ru colloids in the freshly produced catalyst.
• the hydrogenation-active fluid is in permanent contact with the material to be treated during the first use of the catalyst and thus ensures an apparently higher activity. For practical applications, however, it is desirable to maintain the catalyst activity as constant as possible over the life of the catalyst.
• DE-A 198 27 844 describes a process for the production of coated catalysts with a defined shell thickness on porous ceramic supports.
• CVD chemical vapor deposition
• allyl / cyclopentadienyl palladium and trimethylphosphine-methylgold are used as precursors.
• the shell thickness can be controlled and adapted to the catalytic requirements.
• the compound of the catalytically active metal is evaporated and deposited on the solid support from the vapor phase.
• a carrier gas is used at reduced pressures of up to 10 " torr.
• the temperature of the furnace is generally in the range from 20 to 600 ° C., while the temperature of the reservoir is in the range from 20 to 100 ° C.
• Reduction of the catalyst precursors to the catalyst can be achieved by using hydrogen as the carrier gas or by using separate reducing agents.
• the procedure of the CVD process is complex since the vaporized metal precursor has to be carried onto the catalyst carrier with the aid of a carrier gas Universally applicable to metal precursors, since not all precious metal precursors show a suitable evaporation behavior.
• the object of the present invention is to provide a method for producing shell catalysts which enables the formation of sharp shell profiles in the shell catalyst in an uncomplicated manner.
• the catalysts obtained should preferably have a less pronounced deactivation behavior when the catalyst is reused compared to catalysts obtained by conventional processes.
• the catalysts be more active and / or more selective than fixed bed catalysts made by known methods.
• the object is achieved according to the invention by a process for the preparation of coated catalysts which contain at least one catalytically active metal on an inorganic or carbon support, by mixing at least one solid, preferably evaporable, precursor material of the at least one catalytically active metal with the inorganic support and heating of the mixture thus obtained with further mixing until there is no longer any separate solid precursor material, preferably to a temperature at which the precursor material evaporates.
• Mixing is preferably carried out in a rotary kiln or other moving ovens or ovens with mixer internals.
• the mixing is carried out until the precursor material is completely absorbed by the carrier material, so that there is no longer a separate solid precursor material.
• the mixing device ensures a pronounced solid-solid contact and solid-solid transition in the mixture during heating. All mixing devices suitable for this can be used according to the invention. Usually the room temperature (20 ° C.) is heated to a maximum temperature in the range of up to 600 ° C., particularly preferably up to 400 ° C.
• the solid (vaporizable) precursor material of the at least one catalytically active metal and the inorganic or carbon carrier are preferably added to the mixing device in a form which allows intensive solid-solid contact. This means that the outer surface of the materials should be high.
• the inorganic or carbon carrier is therefore preferably used in the form of moldings, granules, strands, pellets, grit, tablets or prills.
• the solid (evaporable) precursor material is preferably used in powder form.
• the mixing device can contain additional internals or balls, for example, which intensify the mixing process.
• the inorganic or carbon carrier and the solid (vaporizable) precursor material are preferably used in an amount which corresponds to the quantitative ratio of the catalytically active material to the inorganic or carbon carrier in the later catalyst correspond.
• the solid (evaporable) precursor material is preferably used in such an amount that the proportion of the catalytically active metal in the finished catalyst is 0.01 to 10% by weight, particularly preferably 0.02 to 2% by weight, based on the total weight of the catalyst.
• the inorganic carrier is preferably selected from SiO 2 , Al 2 O 3 , TiO 2 , ZrO 2 , MgO, mixed oxides or mixtures thereof, SiC or Si 3 N 4 .
• the inorganic or carbon carrier can be present, for example, in the form of spheres, tablets, rings, stars or other shaped bodies.
• the diameter or the length and thickness of the inorganic or carbon carrier particles is preferably in the range from 0.5 to 15 mm, particularly preferably 3 to 9 mm.
• the surface of the carrier can be chosen freely depending on the practical conditions for the respective application.
• the surface of the support is preferably 10 to 2000 m 2 / g.
• the surface area of the inorganic support is preferably 10 to 500 m 2 / g, particularly preferably 20 to 250 m 2 / g.
• the pore volume can also be freely selected depending on the area of application.
• the pore volume is preferably 0.2 to 2 ml / g, particularly preferably 0.3 to 1.2 ml / g. Suitable carriers are known to the person skilled in the art.
• the solid, preferably evaporable, precursor material of the at least one catalytically active metal contains the metal in oxidation state 0.
• a subsequent reduction of the precursor material can be dispensed with, since the precursor material decomposes on the inorganic or carbon support and deposits the catalytically active metal directly in metal form.
• metal carbonyls can be used as vaporizable precursor materials, provided that they interact sufficiently with the support or are volatile to enable absorption.
• triruthenium dodecacarbonyl is a source of ruthenium that is sufficiently volatile and contains the ruthenium in redox stage 0.
• Examples of solid evaporated precursors of at least one catalytically active metal, in which the metal is in oxidation state 0, are Ru 3 (CO) 12 carbonyls from Re, Co, Ni, metallocenes from Ru, Co, Ni, cyclopentadienyls from Co, Rh, Ir, Cu, Ag.
• the solid, preferably evaporable, precursor material of the at least one catalytically active metal can contain the metal in the oxidation state +1 or higher.
• the inorganic or carbon carrier preferably contains a reducing agent for the metal and is used in this form to produce the catalyst according to the invention.
• the at least one catalytically active metal is preferably selected from Pd, Au, Pt, Ag, Rh, Re, Ru, Cu, Ir, Ni, Co and mixtures thereof, particularly preferably selected from Ru, Pd, Pt, Ag, Rh and Au , especially from Ru, Pd and Pt.
• Suitable precursors are, for example, metal compounds or complexes which have silyl, halogen, acetylacetonate, hexafluoroacetylacetonate, cyclopentadiene, trifluoroacetylacetonate, alkyl, aryl or CO as components.
• Suitable Au precursors are, for example, Me 2 Au (hfac), Me 2 Au (tfac), Me Au (acac), Me 3 Au (PMe 3 ), CF 3 Au (PMe 3 ), (CF 3 ) 3 Au (PMe 3 ), MeAuP (OMe) 2 Bu ⁇ , MeAuP (OMe) 2 Me and MeAu (PMe 3 ).
• Me 3 PAuMe is preferred.
• Suitable Ru precursor materials are, for example, Ru (acac 3 ) and Ru 3 (CO) ⁇ 2 .
• the reducing agent with which the inorganic or carbon carrier can be impregnated can be a solution of an organic or inorganic reductant.
• the reducing agent can be selected from ammonium formate and sodium borohydride.
• Ammonium formate is particularly preferably used as the reducing agent, the support being impregnated with an A-ammonium formate solution before the preparation of the coated catalyst. It is also possible to carry out other thermal or chemical reduction processes that can be used to fix the metals.
• the amount of reducing agent, especially ammonium formate, is selected according to practical requirements.
• the amount is preferably chosen so large that a complete reduction of the catalytically active metal is possible under the production conditions.
• catalytically active metals are particularly preferably applied to the inorganic support by the process according to the invention.
• the ligands can be removed from the coated catalyst, for example by applying reduced pressure or exposure to elevated temperature, so that no residue of the precursor material remains in the catalyst. This prevents contamination of the coated catalytic converter.
• the process parameters such as the amount of starting materials, temperature profile, contact time, etc. allow simple control and control of the shell thickness, which can thus be adapted to practical requirements.
• the use of a carrier gas and the cumbersome handling of the precursors can be dispensed with.
• the method according to the invention it is possible to obtain shell catalysts with a much sharper shell profile than was previously possible.
• the metal dispersion and uniformity of the coating are also improved. It is possible to produce essentially monomodal and narrow-band particle size distributions with very small particles.
• the average particle diameter of the catalytically active metals is preferably 1 to 100 ⁇ m, particularly preferably 2 to 10 ⁇ m.
• the method according to the invention also allows the shell thickness and the concentration of the catalytically active metal to be adapted and controlled to the respective requirements. If suitable organometallic precursor compounds are used, the catalytically active metals can be fixed on the inorganic support without residue.
• Preferred shell thicknesses are in the range from 1 to 750 ⁇ m, particularly preferably 5 to 300 ⁇ m.
• the proportion of active metal in the catalysts according to the invention can be reduced without impairing the catalyst performance. It is also possible to provide more active and more selective catalysts for a wide variety of reactions.
• the present invention also relates to a coated catalyst which can be obtained by the above process.
• coated catalysts according to the invention can be used for all suitable applications. They are preferably used in hydrogenations. This applies in particular to catalysts which contain ruthenium, palladium or platinum as catalytically active metals.
• the catalysts according to the invention show a significantly less pronounced deactivation behavior than catalysts produced by conventional processes.
• no colloid of the catalytically active metal is observed in the solution. From this it is clear that no colloids detach from the freshly produced catalyst.
• SiO 2 strands [diameter 3 mm] were first impregnated with an animomorph solution (5% ammonium formate, based on the support) and then dried.
• the material obtained was incorporated together with 1% Ru (acac) 3 , based on the metal, as a solid in a rotary ball oven and at 110 ° C. for 4 hours and then within 100 min. heated to 300 ° C and held at this temperature for 4 hours. At this temperature, the Ru (acac) 3 evaporates, migrates to the strands and is reduced by the ammonium formate. This leads to the formation of a very sharp shell profile.
• the shell thickness was approximately 300 ⁇ m.
• the acetylacetonate only partially decomposes on the catalyst surface and forms a less pronounced profile.
• the remaining part of the ruthenium is deposited between the strands as a fine black powder or discharged from the furnace as acetylacetonate with the gas stream.
• the catalyst obtained according to the invention contains 1% Ru on SiO 2 as a carrier.
• a catalyst was produced by impregnating the SiO 2 support with a ruthenium salt solution and subsequent reduction.
• the catalyst according to the invention and the comparative catalyst were used for the hydrogenation of dextrose to sorbitol.
• the depletion was determined once on a freshly prepared catalyst and then on a reused catalyst. The results are summarized in the table below.
• the catalyst according to the invention predominantly had Ru particles with dimensions in the range from 2 to 100 nm.
• the Pd / Al 2 O 3 catalyst was produced as follows:
• the support was impregnated with 5% ammonium formate as in Example 1 and dried. Then 0.025% Pd in the form of Pd (acac) was mixed with the carrier and in a rotary kiln at 10 ° C / min. heated to 300 ° C and held at 300 ° C for 1 hour.
• This catalyst was tested in the C 2 hydrogenation.
• the selectivity of the Pd / Al 2 O 3 catalysts obtained according to classic tretic methods was clearly exceeded (30% compared to 10 to 15% for the comparative catalyst).
• the catalyst was prepared from SiO 2 and triruthenium dodecacarbonyl as follows:
• Ru 3 (Co) ⁇ 2 with 3 mm SiO 2 lengths were introduced as Ru 3 (Co) ⁇ 2 with 3 mm SiO 2 lengths in a rotary ball oven and heated to 300 ° C. within one hour and kept at this temperature for 2 hours.
• the SiO 2 carrier was not pre-soaked with a reducing agent.

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• 2002
  • 2002-02-26 DE DE10208113A patent/DE10208113A1/de not_active Withdrawn
• 2003
  • 2003-02-25 US US10/504,316 patent/US20050154236A1/en not_active Abandoned
  • 2003-02-25 KR KR20047013214A patent/KR20040091073A/ko not_active Withdrawn
  • 2003-02-25 WO PCT/EP2003/001892 patent/WO2003072248A1/de not_active Application Discontinuation
  • 2003-02-25 CN CNA038046717A patent/CN1638869A/zh active Pending
  • 2003-02-25 AU AU2003212270A patent/AU2003212270A1/en not_active Abandoned
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  • 2003-02-25 CA CA002477378A patent/CA2477378A1/en not_active Abandoned
• 2004
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