EP2667968A2 - Catalyst support produced by flame spray pyrolysis and catalyst for autothermal propane dehydrogenation - Google Patents

Catalyst support produced by flame spray pyrolysis and catalyst for autothermal propane dehydrogenation

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Publication number
EP2667968A2
EP2667968A2 EP12739435.1A EP12739435A EP2667968A2 EP 2667968 A2 EP2667968 A2 EP 2667968A2 EP 12739435 A EP12739435 A EP 12739435A EP 2667968 A2 EP2667968 A2 EP 2667968A2
Authority
EP
European Patent Office
Prior art keywords
catalyst
pyrolysis
particles
carrier
zirconium
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP12739435.1A
Other languages
German (de)
French (fr)
Inventor
Stefan Hannemann
Dieter Stuetzer
Goetz-Peter Schindler
Peter Pfab
Frank Kleine Jaeger
Dirk Grossschmidt
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BASF SE
Original Assignee
BASF SE
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Filing date
Publication date
Application filed by BASF SE filed Critical BASF SE
Priority to EP12739435.1A priority Critical patent/EP2667968A2/en
Publication of EP2667968A2 publication Critical patent/EP2667968A2/en
Withdrawn legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G25/00—Compounds of zirconium
    • C01G25/02—Oxides
    • 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
    • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • B01J21/066—Zirconium or hafnium; Oxides or hydroxides thereof
    • 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
    • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • B01J21/08—Silica
    • 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
    • B01J23/54—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
    • B01J23/56—Platinum group 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
    • B01J23/54—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
    • B01J23/56—Platinum group metals
    • B01J23/62—Platinum group metals with gallium, indium, thallium, germanium, tin or lead
    • B01J23/622—Platinum group metals with gallium, indium, thallium, germanium, tin or lead with germanium, tin or lead
    • B01J23/626—Platinum group metals with gallium, indium, thallium, germanium, tin or lead with germanium, tin or lead with tin
    • 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
    • B01J23/54—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
    • B01J23/56—Platinum group metals
    • B01J23/63—Platinum group metals with rare earths or actinides
    • 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
    • B01J23/90—Regeneration or reactivation
    • B01J23/96—Regeneration or reactivation of catalysts comprising metals, oxides or hydroxides of the 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
    • 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
    • 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
    • B01J37/036—Precipitation; Co-precipitation to form a gel or a cogel
    • 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
    • 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
    • B01J37/34—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation
    • B01J37/349—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of flames, plasmas or lasers
    • 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
    • B01J38/00—Regeneration or reactivation of catalysts, in general
    • B01J38/04—Gas or vapour treating; Treating by using liquids vaporisable upon contacting spent catalyst
    • B01J38/10—Gas or vapour treating; Treating by using liquids vaporisable upon contacting spent catalyst using elemental hydrogen
    • 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
    • B01J38/00—Regeneration or reactivation of catalysts, in general
    • B01J38/04—Gas or vapour treating; Treating by using liquids vaporisable upon contacting spent catalyst
    • B01J38/12—Treating with free oxygen-containing gas
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/18—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof
    • C01B33/187—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof by acidic treatment of silicates
    • C01B33/193—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof by acidic treatment of silicates of aqueous solutions of silicates
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
    • C07C5/32—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen
    • C07C5/327—Formation of non-aromatic carbon-to-carbon double bonds only
    • C07C5/333—Catalytic processes
    • C07C5/3335—Catalytic processes with metals
    • C07C5/3337—Catalytic processes with metals of the platinum group
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2521/00—Catalysts comprising the elements, oxides or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium or hafnium
    • C07C2521/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2521/00—Catalysts comprising the elements, oxides or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium or hafnium
    • C07C2521/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • C07C2521/08—Silica
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
    • C07C2523/02—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of the alkali- or alkaline earth metals or beryllium
    • C07C2523/04—Alkali metals
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
    • C07C2523/10—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of rare earths
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
    • C07C2523/14—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of germanium, tin or lead
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
    • C07C2523/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of noble metals
    • C07C2523/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of noble metals of the platinum group metals
    • C07C2523/42—Platinum
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
    • C07C2523/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of noble metals
    • C07C2523/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of noble metals combined with metals, oxides or hydroxides provided for in groups C07C2523/02 - C07C2523/36
    • C07C2523/56—Platinum group metals
    • C07C2523/62—Platinum group metals with gallium, indium, thallium, germanium, tin or lead
    • 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
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/584—Recycling of catalysts

Definitions

  • the invention relates to oxidic catalyst supports and catalyst particles prepared therefrom, to a process for their preparation and to the use of the catalyst particles as dehydrogenation catalyst.
  • DE-A 196 54 391 describes the preparation of a dehydrogenation catalyst by impregnation of essentially monoclinic ZrO 2 with a solution of Pt (NO 3 ) 2 and Sn (OAc) 2 or by impregnation of ZrO 2 with a first solution of Pt (NO 3 ) 2 and then a second solution of La (NO 3 ) 3 .
  • the impregnated carriers are dried and then calcined.
  • the catalysts thus obtained are used as dehydrogenation catalysts, for example for the dehydrogenation of propane to propene.
  • the preparation of the catalyst support is usually carried out by the sol-gel method, precipitation of the salts, dewatering of the corresponding acids, dry mixing, slurrying or spray drying.
  • a ZrO AI 2 0 3 "Si0 2 mixed oxide can first a water-rich zirconia of the general formula ZrO xH 2 0 containing by precipitation of a suitable zirconium precursor be prepared. Suitable precursors of the zirconium are, for example, Zr (NO 3 ) 4 , ZrOCl 2 , or ZrCl 4 .
  • the precipitation itself is carried out by adding a base such as NaOH, KOH, Na 2 C0 3 and NH 3 and is described for example in EP-A 0 849 224.
  • the zirconium-containing precursor can be mixed with a precursor containing silicon.
  • a precursor containing silicon for example, hydrous sols of Si0 2 such as Ludox TM.
  • the mixture of the two components can be carried out, for example, by simple mechanical mixing or by spray-drying in a spray tower.
  • a known process for the preparation of metal catalysts by flame spray pyrolysis is described in Pisduangnawakij et al., Applied Catalysis A: General 370 1-6, 2009.
  • a solution containing precursor compounds of platinum and tin and of alumina as a carrier in xylene is converted into an aerosol, this treated in an inert carrier gas in a pyrolysis reactor at a temperature above the decomposition temperature of the precursor compounds and then separated the finely divided metal formed from the carrier gas ,
  • the object of the present invention is to provide a cost-effective and time-saving process for the preparation of oxidic supports for dehydrogenation catalysts, wherein the resulting dehydrogenation catalysts should be comparable in activity and selectivity with the prior art catalysts prepared exclusively by impregnation or spray drying.
  • the object is achieved by a method for producing catalyst carrier particles containing zirconium dioxide and optionally silicon oxide, comprising the steps
  • the oxide-forming precursor compounds are fed to the pyrolysis zone as an aerosol. It is expedient to supply to the pyrolysis zone an aerosol which has been obtained by nebulization of only one solution which contains all oxide-forming precursor compounds. In this way, it is ensured in each case that the composition of the particles produced is homogeneous and constant.
  • the individual components are therefore preferably selected so that the oxide-forming precursors present in the solution are present in homogeneously dissolved state until the solution has been atomized.
  • the solution or solutions may contain both polar and non-polar solvents or solvent mixtures.
  • the temperature in the pyrolysis zone is at a sufficient temperature for oxide formation, usually in the range between 500 and 2000 ° C.
  • the pyrolysis is carried out at a temperature of 900 to 1500 ° C.
  • the pyrolysis reactor can be indirectly heated from the outside, for example by means of an electric furnace. Because of the temperature gradient from outside to inside required for indirect heating, the furnace must be much hotter than the temperature required for pyrolysis. Indirect heating requires a temperature-stable furnace material and a complex reactor design, the required total amount of gas is, on the other hand, lower than in the case of a flame reactor.
  • the pyrolysis zone is heated by a flame (flame spray pyrolysis).
  • the pyrolysis zone then comprises an ignition device.
  • conventional fuel gases can be used, but preferably hydrogen, methane or ethylene are used.
  • the temperature can be adjusted in the pyrolysis zone targeted.
  • the pyrolysis zone instead of air as a source of 0 2 for the combustion of the fuel gas and pure oxygen can be supplied.
  • the total amount of gas also includes the carrier gas for the aerosol and the vaporized solvent of the aerosol.
  • the one or more of the pyrolysis zone supplied aerosols are conveniently passed directly into the flame. While air is usually preferred as the carrier gas for the aerosol, it is also possible to use nitrogen, CO 2 , O 2 or a fuel gas, for example hydrogen, methane, ethylene, propane or butane.
  • the pyrolysis zone is heated by an electrical plasma or an inductive plasma.
  • a flame spray pyrolysis device generally comprises a reservoir for the liquid to be atomized, feed lines for carrier gas, fuel gas and oxygen-containing gas, a central aerosol nozzle and an annular burner arranged around it, a device for gas-solid separation comprising a filter element and a removal device for the solid and an outlet for the exhaust gas.
  • the cooling of the particles is carried out by means of a quenching gas, e.g. Nitrogen or air.
  • the combustion chamber which is preferably tubular, is thermally insulated.
  • a pyrolysis gas containing spherical particles of varying specific surface area is obtained.
  • the size distribution of the particles obtained gives inter alia from the droplet size spectrum of the aerosol supplied to the pyrolysis zone and the concentration of the solution or solutions used.
  • the pyrolysis gas is cooled sufficiently before deposition of the particles formed from the pyrolysis gas, so that sintering of the particles is excluded.
  • the pyrolysis zone preferably comprises a cooling zone which adjoins the combustion chamber of the pyrolysis reactor.
  • a cooling of the pyrolysis gas and the catalyst particles contained therein to a temperature of about 100 - 500 ° C is required, depending on the filter element used.
  • a cooling to about 100 - 150 ° C instead.
  • the pyrolysis gas containing the catalyst particles and partially cooled, after leaving the pyrolysis zone, enters an apparatus for separating the particles from the pyrolysis gas, which comprises a filter element.
  • a quenching gas for example nitrogen, air or a water humidified gas is introduced.
  • Suitable zirconia-forming precursor compounds are alcoholates, such as zirconium (IV) ethanolate, zirconium (IV) n-propoxide, zirconium (IV) isopropoxide, zirconium (IV) n-butoxide and zirconium (IV) -tert butoxide.
  • zirconium (IV) propoxide which is preferably in the form of a solution in n-propanol, is used as the ZrO 2 precursor compound.
  • Suitable zirconia-forming precursor compounds are also carboxylates such as zirconium acetate, zirconium propionate, zirconium oxalate, zirconium octoate, zirconium 2-ethylhexanoate, zirconium acetate, zirconium propionate, zirconium oxalate, zirconium octanoate, zirconium 2-ethylhexanoate, zirconium neodecanoate, zirconium stearate and zirconium propionate.
  • zirconium (IV) acetylacetonate is used as precursor compound.
  • the precursor compounds additionally comprise a silica precursor compound.
  • Suitable precursors for silicon dioxide are organosilanes and reaction products of SiCl 4 with lower alcohols or lower carboxylic acids. It is also possible to use condensates of the stated organosilanes or silanols with Si-O-Si members. Preference is given to using siloxanes. The use of Si0 2 is also possible.
  • the precursor compounds comprise, as the precursor compound which forms the silica, hexamethyldisiloxane. To prepare the solution or solutions required for aerosol formation, it is possible to use both polar and apolar solvents or solvent mixtures.
  • Preferred polar solvents are water, methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, n-propanone, n-butanone, diethyl ether, tert-butyl methyl ether, tetrahydrofuran, CrC 8 -Carboxylic acids, ethyl acetate and mixtures thereof.
  • one or more precursor compounds are dissolved in a mixture of acetic acid, ethanol and water.
  • this mixture contains 30 to 75 wt .-% acetic acid, 30 to 75 wt .-% ethanol and 0 to 20 wt .-% water.
  • zirconium (IV) acetylacetonate, hexamethyldisiloxane are dissolved in a mixture of acetic acid, ethanol and water.
  • Preferred apolar solvents are toluene, xylene, n-heptane, n-pentane, octane, isooctane, cyclohexane, methyl, ethyl or butyl acetate or mixtures thereof. Hydrocarbons or mixtures of hydrocarbons with 5 to 15 carbon atoms are also suitable. Especially preferred is xylene.
  • Zr (IV) -ethylhexanoate and hexamethyldisiloxane are dissolved in xylene.
  • the catalyst carrier particles obtained by spray pyrolysis preferably have a specific surface area of 36 to 70 m 2 / g.
  • the resulting catalyst support particles are then impregnated with one or more solutions containing compounds of platinum, tin and at least one other element selected from lanthanum and cesium.
  • the impregnated catalyst support particles are dried and calcined.
  • the invention thus also provides a process for the preparation of catalyst particles comprising platinum and tin and at least one further element selected from lanthanum and cesium on a zirconium dioxide-containing support, the process comprising steps (i) to (v) and additionally the steps
  • precursor compounds are usually used compounds which can be converted by calcination in the corresponding oxides. Suitable examples are hydroxides, carbonates, oxalates, acetates, chlorides or mixed hydroxycarbonates of the corresponding metals.
  • the application of the dehydrogenating component is usually carried out by impregnation. Instead of impregnation, however, the dehydrogenating component can also be carried out by other methods, such as, for example, spraying on the metal salt precursor.
  • Platinum is preferably used as H 2 PtCl 6 or Pt (NO 3 ) 2 .
  • Suitable solvents are water as well as organic solvents. Particularly suitable are water and lower alcohols such as methanol and ethanol.
  • Suitable precursors in the use of noble metals as the dehydrogenating component are also the corresponding noble metal sols, which can be prepared by one of the known methods, for example by reduction of a metal salt in the presence of a stabilizer such as PVP with a reducing agent.
  • a stabilizer such as PVP with a reducing agent.
  • the manufacturing technique is discussed in detail in the German patent application DE 195 00 366.
  • the content of platinum in the catalyst as the dehydrogenating component is from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, particularly preferably from 0.05 to 0.5% by weight.
  • the catalyst contains at least tin in amounts of 0.01 to 10 wt .-%, preferably 0.05 to 2 wt .-%.
  • Suitable tin compounds are carboxylates such as tin (II) acetate, tin 2-ethylhexanoate or tin (II) chloride.
  • the loading with Pt is 0.05 to 1 wt .-% and the loading with Sn 0.05 to 2 wt .-%.
  • the active composition may contain the following further components, wherein at least cesium or lanthanum are contained:
  • Cesium and optionally potassium with a content between 0.1 and 10% by weight are included in cesium or Kalimoxidprecursoren using compounds that are can be converted by calcination in the oxides, for example, the hydroxides, carbonates, oxalates, acetates or formates.
  • the precursor salts suitable are, for example, lanthanum oxide carbonate, La (OH) 3 , La 2 (CO 3 ) 3, La (NO 3 ) 3, lanthanum formate, lanthanum acetate and lanthanum oxalate.
  • the calcination takes place at temperatures of 400 to 1000 ° C, preferably from 500 to 700 ° C, more preferably at 550 to 650 ° C.
  • the present invention also provides the carrier and catalyst particles obtainable by the process according to the invention. These preferably have a specific surface area of 20 to 70 m 2 / g.
  • the catalyst supports have the following percentage composition: 30 to 99.5% by weight Zr0 2 , 0.5 to 25% by weight Si0 2 .
  • the catalyst particles further contain 0.1 to 1 wt .-% Pt, 0.1 to 10 wt .-% Sn, La and / or Cs, based on the mass of the carrier, wherein at least Sn and at least La or Cs are included.
  • the present invention also relates to the use of the catalyst particles as hydrogenation catalysts or dehydrogenation catalysts.
  • Alkanes such as butane and propane, but also ethylbenzene are preferably dehydrated.
  • catalysts of the invention for the dehydrogenation of propane to propene.
  • HMDSO Hexamethyldisiloxane
  • the solvent is HoAc: EtOH: H 2 O in the mass ratio 4.6 to 4.6 to 1.
  • the acetic acid-ethanol mixture is freshly prepared. This dissolves the precursor compounds for Si and Zr. Alternatively, xylene is used.
  • Table 1 Compositions of solutions of precursor compounds for apolar
  • the solution containing the precursor compounds was fed by means of a piston pump via a two-fluid nozzle and sprayed with an appropriate amount of air.
  • a support flame was partially used from an ethylene-air mixture, which was metered via a ring burner located around the nozzle.
  • the pressure drop was kept constant at 1, 1 bar.
  • Table 2 summarizes the flame synthesis conditions.
  • Xylene 1 310 3500 1200 A baghouse filter was used to separate the particles. To clean these filters, the filter bags were subjected to 5 bar pressure surges of nitrogen.
  • the impregnation was carried out according to Example 4 of EP 1 074 301.
  • the flame-synthesized Si0 2 / Zr0 2 support of the 1 to 2 mm sieve fraction was poured over a solution of SnCl 2 and H 2 PtCl 6 in ethanol.
  • the excess solution was removed on a rotary evaporator, the solid dried and calcined.
  • An aqueous solution of CsN0 3 and La (NO 3 ) 3 was added thereto and the supernatant was removed.
  • the catalyst was obtained after drying and calcining with a BET surface area of 23 m 2 .
  • the reference catalyst according to EP 1 074 301 consists of 95% by weight Zr0 2 , 5% by weight Si0 2 (carrier), 0.5% by weight Pt, 1% by weight Sn, 3% La, 0, 5 wt .-% Cs and 0.2 wt .-% K (active and promoter metals based on the mass of the carrier) prepared according to Example 4 by wet-chemical means.
  • the support was prepared by spray-drying the oxide mixture obtained by precipitation by the sol / gel process.
  • the propane dehydrogenation was carried out at about 600 ° C. 21 Nl / h of total gas (20 Nl / h of propane, 1 Nl / h of nitrogen as internal standard), 5 g / h of water.
  • the regeneration is carried out at 400 ° C: 2 hours 21 Nl / h N 2 + 4 Nl / h air; 2 hours 25 Nl / h air; 1 hour 25 Nl / h of hydrogen.
  • FIG. 1 shows for comparison the activities and selectivities of the reference catalyst (-) with support prepared by precipitation and spray-drying and the catalyst according to the invention whose support originates from the flame synthesis ( ⁇ ), the other elements being applied in each case by impregnation.
  • the results for a flame-only synthesized catalyst of the same composition (A) are also shown.
  • the abscissa shows the time in hours the ordinate shows conversions (40 to 50%) and selectivities (> 80%) for the autothermal dehydrogenation of propane to propene.
  • the reference catalyst has lower initial selectivities. However, it is similar to the test cycles of a few weeks.
  • the flame-synthesized catalyst and the flame-synthesized carrier after wet-chemical application of the other elements behave like an aged catalyst whose carrier was prepared by spray-drying.

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Abstract

The invention relates to a method for producing catalyst support particles containing zirconium dioxide and optionally silicon oxide, comprising the following steps: (i) a solution containing precursor compounds of zircon dioxide and optionally silicon dioxide is prepared; (ii) the solution(s) is/are converted into an aerosol; (iii) the aerosol is introduced into a pyrolysis zone that is directly or indirectly heated; (iv) pyrolysis is carried out; (v) the catalyst particles that have been formed are separated from the pyrolysis gas.

Description

Katalysatorträger aus der Flammen-Spraypyrolyse und Katalysator für die Autotherme Propandehydrierung  Catalyst carrier from flame spray pyrolysis and catalyst for the autothermal propane dehydrogenation
Beschreibung description
Die Erfindung betrifft oxidische Katalysatorträger und daraus hergestellte Katalysatorpartikel, ein Verfahren zu ihrer Herstellung sowie die Verwendung der Katalysatorpartikel als Dehydrierkatalysator. The invention relates to oxidic catalyst supports and catalyst particles prepared therefrom, to a process for their preparation and to the use of the catalyst particles as dehydrogenation catalyst.
Es ist bekannt, Dehydrierkatalysatoren durch Tränkprozesse oder Sprühtrocknung herzustellen. Bei diesen Verfahren werden auf einen oxidischen Träger oder einen Silikatträger die katalytisch aktiven Metalle durch Tränkprozesse aufgebracht oder der Katalysator durch Sprühtrocknung von gemeinsam gefällten Oxidvorläufern hergestellt. It is known to produce dehydrogenation catalysts by impregnation or spray drying. In these processes, the catalytically active metals are applied to an oxidic support or a silicate support by impregnation processes, or the catalyst is prepared by spray-drying co-precipitated oxide precursors.
DE-A 196 54 391 beschreibt die Herstellung eines Dehydrierkatalysators durch Tränkung von im Wesentlichen monoklinem Zr02 mit einer Lösung von Pt(N03)2 und Sn(OAc)2 bzw. durch Tränkung des Zr02 mit einer ersten Lösung von Pt(N03)2 und anschließend einer zweiten Lösung von La(N03)3. Die imprägnierten Träger werden getrocknet und anschließend calciniert. Die so erhaltenen Katalysatoren werden als Dehydrierkatalysatoren, z.B. für die Dehydrierung von Propan zu Propen eingesetzt. DE-A 196 54 391 describes the preparation of a dehydrogenation catalyst by impregnation of essentially monoclinic ZrO 2 with a solution of Pt (NO 3 ) 2 and Sn (OAc) 2 or by impregnation of ZrO 2 with a first solution of Pt (NO 3 ) 2 and then a second solution of La (NO 3 ) 3 . The impregnated carriers are dried and then calcined. The catalysts thus obtained are used as dehydrogenation catalysts, for example for the dehydrogenation of propane to propene.
Die Herstellung der Katalysatorträger erfolgt üblicher Weise nach dem Sol-Gel- Verfahren, Fällung der Salze, Entwässern der entsprechenden Säuren, Trockenmischen, Aufschlämmen oder Sprühtrocknen. Zum Beispiel kann zur Herstellung eines ZrO AI203«Si02-Mischoxides zunächst ein wasserreiches Zirkonoxid der allgemeinen Formel ZrO xH20 durch Fällung eines geeigneten Zirkon enthaltenden Precursors hergestellt werden. Geeignete Precursoren des Zirkons sind zum Beispiel Zr(N03)4, ZrOCI2, oder ZrCI4 . Die Fällung selbst erfolgt durch Zugabe einer Base wie zum Beispiel NaOH, KOH, Na2C03 und NH3 und ist beispielsweise in der EP-A 0 849 224 beschrieben. The preparation of the catalyst support is usually carried out by the sol-gel method, precipitation of the salts, dewatering of the corresponding acids, dry mixing, slurrying or spray drying. For example, to prepare a ZrO AI 2 0 3 "Si0 2 mixed oxide can first a water-rich zirconia of the general formula ZrO xH 2 0 containing by precipitation of a suitable zirconium precursor be prepared. Suitable precursors of the zirconium are, for example, Zr (NO 3 ) 4 , ZrOCl 2 , or ZrCl 4 . The precipitation itself is carried out by adding a base such as NaOH, KOH, Na 2 C0 3 and NH 3 and is described for example in EP-A 0 849 224.
Zur Herstellung eines ZrO Si02-Mischoxides kann der Zirkon enthaltende Precursor mit einem Silizium enthaltenden Precursor gemischt werden. Gut geeignete Precursoren für Si02 sind zum Beispiel wasserhaltige Sole des Si02 wie Ludox™. Die Mischung der beiden Komponenten kann beispielsweise durch einfaches mechanisches Vermischen oder durch Sprühtrocknen in einem Sprühturm erfolgen. Ein bekanntes Verfahren zur Herstellung von Metallkatalysatoren durch Flammen-Spray- Pyrolyse wird in Pisduangnawakij et al., Applied Catalysis A: General 370 1-6, 2009 beschrieben. Dabei wird eine Lösung enthaltend Vorläuferverbindungen von Platin und Zinn sowie von Aluminiumoxid als Träger in Xylol in ein Aerosol überführt, dieses in einem inerten Trägergas in einem Pyrolysereaktor bei einer Temperatur oberhalb der Zersetzungstemperatur der Precursorverbindungen behandelt und anschließend das gebildete feinteili- ge Metall vom Trägergas abgetrennt. To prepare a ZrO Si0 2 mixed oxide, the zirconium-containing precursor can be mixed with a precursor containing silicon. Well-suited precursors for Si0 2 are, for example, hydrous sols of Si0 2 such as Ludox ™. The mixture of the two components can be carried out, for example, by simple mechanical mixing or by spray-drying in a spray tower. A known process for the preparation of metal catalysts by flame spray pyrolysis is described in Pisduangnawakij et al., Applied Catalysis A: General 370 1-6, 2009. In this case, a solution containing precursor compounds of platinum and tin and of alumina as a carrier in xylene is converted into an aerosol, this treated in an inert carrier gas in a pyrolysis reactor at a temperature above the decomposition temperature of the precursor compounds and then separated the finely divided metal formed from the carrier gas ,
Aufgabe der vorliegenden Erfindung ist es, ein kostengünstiges und zeitsparendes Verfahren zur Herstellung von oxidischen Trägern für Dehydrierkatalysatoren bereitzustellen, wobei die erhaltenen Dehydrierkatalysatoren hinsichtlich Aktivität und Selektivität mit den ausschließlich durch Tränkprozesse bzw. Sprühtrocknung hergestellten Katalysatoren des Standes der Technik vergleichbar sein sollen. The object of the present invention is to provide a cost-effective and time-saving process for the preparation of oxidic supports for dehydrogenation catalysts, wherein the resulting dehydrogenation catalysts should be comparable in activity and selectivity with the prior art catalysts prepared exclusively by impregnation or spray drying.
Gelöst wird die Aufgabe durch ein Verfahren zur Herstellung von Katalysatorträgerpartikeln, enthaltend Zirkondioxid und optional Siliciumoxid, umfassend die Schritte The object is achieved by a method for producing catalyst carrier particles containing zirconium dioxide and optionally silicon oxide, comprising the steps
(i) Bereitstellung einer Lösung enthaltend Vorläuferverbindungen von Zirkondioxid und optional von Siliciumoxid, (i) providing a solution containing precursor compounds of zirconium dioxide and optionally of silica,
(ii) Überführung der Lösung(en) in ein Aerosol,  (ii) transfer of the solution (s) into an aerosol,
(iii) Einbringen des Aerosols in eine direkt oder indirekt beheizte Pyrolysezone,  (iii) introducing the aerosol into a directly or indirectly heated pyrolysis zone,
(iv) Durchführung der Pyrolyse, und  (iv) carrying out the pyrolysis, and
(v) Abscheidung der gebildeten Katalysatorpartikel aus dem Pyrolysegas.  (V) deposition of the catalyst particles formed from the pyrolysis gas.
Die oxidbildenden Vorläuferverbindungen werden der Pyrolysezone als Aerosol zugeführt. Es ist zweckmäßig, der Pyrolysezone ein Aerosol zuzuführen, das durch Vernebe- lung nur einer Lösung erhalten wurde, welche alle oxidbildenden Vorläuferverbindungen enthält. Auf diese Weise ist in jedem Fall gewährleistet, dass die Zusammensetzung der erzeugten Partikel homogen und konstant ist. Bei der Zubereitung der in ein Aerosol zu überführenden Lösung werden die einzelnen Komponenten also vorzugsweise so gewählt, dass die in der Lösung enthaltenen oxidbildenden Vorstufen bis zum Vernebeln der Lösung homogen gelöst nebeneinander vorliegen. Alternativ ist es auch möglich, dass mehrere verschiedene Lösungen, die zum einen die oxidbildenden Vorstufen enthalten, eingesetzt werden. Die Lösung bzw. Lösungen können sowohl polare als auch apolare Lösungsmittel oder Lösungsmittelgemische enthalten. The oxide-forming precursor compounds are fed to the pyrolysis zone as an aerosol. It is expedient to supply to the pyrolysis zone an aerosol which has been obtained by nebulization of only one solution which contains all oxide-forming precursor compounds. In this way, it is ensured in each case that the composition of the particles produced is homogeneous and constant. In the preparation of the solution to be converted into an aerosol, the individual components are therefore preferably selected so that the oxide-forming precursors present in the solution are present in homogeneously dissolved state until the solution has been atomized. Alternatively, it is also possible that several different solutions which contain the oxide-forming precursors are used. The solution or solutions may contain both polar and non-polar solvents or solvent mixtures.
In der Pyrolysezone kommt es zur Zersetzung und/oder Oxidation der Oxid-Vorstufen unter Bildung des Oxids. Als Ergebnis der Pyrolyse werden meist sphärische Partikel mit variierender spezifischer Oberfläche erhalten. Die Temperatur in der Pyrolysezone liegt bei einer für die Oxid-Bildung ausreichenden Temperatur, üblicherweise im Bereich zwischen 500 und 2000 °C. Vorzugsweise wird die Pyrolyse bei einer Temperatur von 900 bis 1500 °C durchgeführt. In the pyrolysis zone, decomposition and / or oxidation of the oxide precursors occurs to form the oxide. As a result of the pyrolysis mostly spherical particles with varying specific surface are obtained. The temperature in the pyrolysis zone is at a sufficient temperature for oxide formation, usually in the range between 500 and 2000 ° C. Preferably, the pyrolysis is carried out at a temperature of 900 to 1500 ° C.
Der Pyrolysereaktor kann indirekt von außen, beispielsweise mittels eines elektrischen Ofens beheizt werden. Wegen des bei der indirekten Beheizung erforderlichen Temperaturgradienten von außen nach innen muss der Ofen wesentlich heißer sein als es der für die Pyrolyse erforderlichen Temperatur entspricht. Eine indirekte Beheizung erfordert ein temperaturstabiles Ofenmaterial und eine aufwendige Reaktorkonstruktion, die benötigte Gesamtgasmenge ist andererseits niedriger als im Falle eines Flammenreaktors. The pyrolysis reactor can be indirectly heated from the outside, for example by means of an electric furnace. Because of the temperature gradient from outside to inside required for indirect heating, the furnace must be much hotter than the temperature required for pyrolysis. Indirect heating requires a temperature-stable furnace material and a complex reactor design, the required total amount of gas is, on the other hand, lower than in the case of a flame reactor.
In einer bevorzugten Ausführungsform wird die Pyrolysezone durch eine Flamme beheizt (Flammen-Sprühpyrolyse). Die Pyrolysezone umfasst dann eine Zündvorrichtung. Zur direkten Beheizung können übliche Brenngase eingesetzt werden, vorzugsweise werden jedoch Wasserstoff, Methan oder Ethylen verwendet. Durch das Verhältnis von Brenngas- zur Gesamtgasmenge kann die Temperatur in der Pyrolysezone gezielt eingestellt werden. Um die Gesamtgasmenge niedrig zu halten und dennoch eine möglichst hohe Temperatur zu erzielen, kann der Pyrolysezone anstelle von Luft als 02-Quelle für die Verbrennung des Brenngases auch reiner Sauerstoff zugeführt werden. Die Gesamtgasmenge umfasst auch das Trägergas für das Aerosol sowie das verdampfte Lösungsmittels des Aerosols. Das oder die der Pyrolysezone zugeführten Aerosole werden zweckmäßigerweise unmittelbar in die Flamme geleitet. Während als Trägergas für das Aerosol meistens Luft bevorzugt wird, ist es auch möglich, Stickstoff, C02, 02 oder ein Brenngas, also beispielsweise Wasserstoff, Methan, Ethylen, Propan oder Butan zu verwenden. In a preferred embodiment, the pyrolysis zone is heated by a flame (flame spray pyrolysis). The pyrolysis zone then comprises an ignition device. For direct heating conventional fuel gases can be used, but preferably hydrogen, methane or ethylene are used. By the ratio of fuel gas to the total amount of gas, the temperature can be adjusted in the pyrolysis zone targeted. In order to keep the total amount of gas low and still achieve the highest possible temperature, the pyrolysis zone instead of air as a source of 0 2 for the combustion of the fuel gas and pure oxygen can be supplied. The total amount of gas also includes the carrier gas for the aerosol and the vaporized solvent of the aerosol. The one or more of the pyrolysis zone supplied aerosols are conveniently passed directly into the flame. While air is usually preferred as the carrier gas for the aerosol, it is also possible to use nitrogen, CO 2 , O 2 or a fuel gas, for example hydrogen, methane, ethylene, propane or butane.
In einer weiteren Ausführungsform des erfindungsgemäßen Verfahrens wird die Pyrolysezone durch ein elektrisches Plasma oder ein induktives Plasma beheizt. In a further embodiment of the method according to the invention, the pyrolysis zone is heated by an electrical plasma or an inductive plasma.
Eine Flammen-Sprühpyrolysevorrichtung umfasst im Allgemeinen einen Vorratsbehälter für die zu vernebelnde Flüssigkeit, Zuleitungen für Trägergas, Brenngas und sauerstoffhaltiges Gas, eine zentrale Aerosoldüse, sowie einen um diese herum angeordneten ringförmigen Brenner, eine Vorrichtung zur Gas-Feststofftrennung umfassend ein Filterelement und eine Entnahmevorrichtung für den Feststoff sowie einen Auslass für das Abgas. Die Abkühlung der Partikel erfolgt mittels eines Quenchgases, z.B. Stickstoff oder Luft. A flame spray pyrolysis device generally comprises a reservoir for the liquid to be atomized, feed lines for carrier gas, fuel gas and oxygen-containing gas, a central aerosol nozzle and an annular burner arranged around it, a device for gas-solid separation comprising a filter element and a removal device for the solid and an outlet for the exhaust gas. The cooling of the particles is carried out by means of a quenching gas, e.g. Nitrogen or air.
Um ein ausgeglichenes Temperaturprofil zu erzeugen, wird der Brennraum, der vorzugsweise rohrförmig ausgebildet ist, wärmeisoliert. In order to produce a balanced temperature profile, the combustion chamber, which is preferably tubular, is thermally insulated.
Als Ergebnis der Pyrolyse wird ein Pyrolysegas erhalten, das sphärische Partikel mit variierender spezifischer Oberfläche enthält. Die Größenverteilung der erhaltenen Partikel ergibt sich unter anderem aus dem Tröpfchengrößenspektrum des der Pyrolysezone zugeführten Aerosols und der Konzentration der eingesetzten Lösung oder Lösungen. As a result of the pyrolysis, a pyrolysis gas containing spherical particles of varying specific surface area is obtained. The size distribution of the particles obtained gives inter alia from the droplet size spectrum of the aerosol supplied to the pyrolysis zone and the concentration of the solution or solutions used.
Vorzugsweise wird das Pyrolysegas vor dem Abscheiden der gebildeten Partikel aus dem Pyrolysegas soweit abgekühlt, dass ein Sintern der Partikel ausgeschlossen wird. Die Pyrolysezone umfasst aus diesem Grund vorzugsweise eine Kühlzone, die sich an den Brennraum des Pyrolysereaktors anschließt. Im Allgemeinen ist eine Abkühlung des Pyrolysegases und der darin enthaltenen Katalysatorpartikel auf eine Temperatur von etwa 100 - 500 °C erforderlich, abhängig von dem verwendeten Filterelement. Vorzugsweise findet eine Abkühlung auf ca. 100 - 150°C statt. Das die Katalysatorpartikel enthaltende und teilweise abgekühlte Pyrolysegas tritt nach Verlassen der Pyrolysezone in eine Vorrichtung zur Abtrennung der Partikel vom Pyrolysegas, welche ein Filterelement umfasst, ein. Zur Abkühlung wird ein Quenchgas, beispielsweise Stickstoff, Luft oder ein mit Wasser befeuchtes Gas eingeleitet. Preferably, the pyrolysis gas is cooled sufficiently before deposition of the particles formed from the pyrolysis gas, so that sintering of the particles is excluded. For this reason, the pyrolysis zone preferably comprises a cooling zone which adjoins the combustion chamber of the pyrolysis reactor. In general, a cooling of the pyrolysis gas and the catalyst particles contained therein to a temperature of about 100 - 500 ° C is required, depending on the filter element used. Preferably, a cooling to about 100 - 150 ° C instead. The pyrolysis gas containing the catalyst particles and partially cooled, after leaving the pyrolysis zone, enters an apparatus for separating the particles from the pyrolysis gas, which comprises a filter element. For cooling, a quenching gas, for example nitrogen, air or a water humidified gas is introduced.
Geeignete Zirkoniumdioxid bildende Vorläuferverbindungen sind Alkoholate, wie Zirkoni- um(IV)-ethanolat, Zirkonium(IV)-n-propanolat, Zirkonium(IV)-isopropanolat, Zirkoni- um(IV)-n-butanolat und Zirkonium(IV)-tert-butanolat. In einer bevorzugten Ausführungsform des erfindungsgemäßen Verfahrens wird als Zr02-Vorläuferverbindung Zirkoni- um(IV)-propanolat, welches vorzugsweise als Lösung in n-Propanol vorliegt, eingesetzt. Suitable zirconia-forming precursor compounds are alcoholates, such as zirconium (IV) ethanolate, zirconium (IV) n-propoxide, zirconium (IV) isopropoxide, zirconium (IV) n-butoxide and zirconium (IV) -tert butoxide. In a preferred embodiment of the process according to the invention, zirconium (IV) propoxide, which is preferably in the form of a solution in n-propanol, is used as the ZrO 2 precursor compound.
Geeignete Zirkoniumdioxid bildende Vorläuferverbindungen sind weiterhin Carboxylate, wie Zirkoniumacetat, Zirkoniumpropionat, Zirkoniumoxalat, Zirkoniumoctoat, Zirkonium- 2-ethyl-hexanoat, Zirkoniumacetat, Zirconpropionat, Zirkoniumoxalat, Zirkoniumoctanoat, Zirkonium-2-ethylhexanoat, Zirkoniumneodecanoat, Zirkoniumstearat und Zirkoniumpropionat. In einer weiteren bevorzugten Ausführungsform des erfindungsgemäßen Verfahrens wird als Vorläuferverbindung Zirkonium(IV)-acetylacetonat eingesetzt. Suitable zirconia-forming precursor compounds are also carboxylates such as zirconium acetate, zirconium propionate, zirconium oxalate, zirconium octoate, zirconium 2-ethylhexanoate, zirconium acetate, zirconium propionate, zirconium oxalate, zirconium octanoate, zirconium 2-ethylhexanoate, zirconium neodecanoate, zirconium stearate and zirconium propionate. In a further preferred embodiment of the process according to the invention zirconium (IV) acetylacetonate is used as precursor compound.
In einer Ausführungsform umfassen die Vorläuferverbindungen zusätzlich eine Siliziumdioxid-Vorläuferverbindung. Als Vorstufe für Siliziumdioxid kommen Organosilane sowie Umsetzungsprodukte von SiCI4 mit niederen Alkoholen oder niederen Carbonsäuren in Frage. Es können auch Kondensate der genannten Organosilane beziehungsweise - silanole mit Si-O-Si Gliedern eingesetzt werden. Bevorzugt werden Siloxane verwendet. Der Einsatz von Si02 ist ebenso möglich. In einer bevorzugten Ausführungsform des erfindungsgemäßen Verfahrens umfassen die Vorläuferverbindungen als Siliziumdioxid bildende Vorläuferverbindung Hexamethyldisiloxan. Zur Herstellung der zur Aerosolbildung erforderlichen Lösung bzw. Lösungen können sowohl polare als auch apolare Lösungsmittel oder Lösungsmittelgemische verwendet werden. In one embodiment, the precursor compounds additionally comprise a silica precursor compound. Suitable precursors for silicon dioxide are organosilanes and reaction products of SiCl 4 with lower alcohols or lower carboxylic acids. It is also possible to use condensates of the stated organosilanes or silanols with Si-O-Si members. Preference is given to using siloxanes. The use of Si0 2 is also possible. In a preferred embodiment of the process of the invention, the precursor compounds comprise, as the precursor compound which forms the silica, hexamethyldisiloxane. To prepare the solution or solutions required for aerosol formation, it is possible to use both polar and apolar solvents or solvent mixtures.
Bevorzugte polare Lösungsmittel sind Wasser, Methanol, Ethanol, n-Propanol, iso- Propanol, n-Butanol, tert.-Butanol, n-Propanon, n-Butanon, Diethylether, tert.-Butyl- methylether, Tetra hydrofu ran, CrC8-Carbonsäuren, Essigsäureethylester sowie deren Gemische. Preferred polar solvents are water, methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, n-propanone, n-butanone, diethyl ether, tert-butyl methyl ether, tetrahydrofuran, CrC 8 -Carboxylic acids, ethyl acetate and mixtures thereof.
In einer bevorzugten Ausführungsform des erfindungsgemäßen Verfahrens werden eine oder mehrere der Vorläuferverbindungen, bevorzugt alle Vorläuferverbindungen in einem Gemisch aus Essigsäure, Ethanol und Wasser gelöst. Bevorzugt enthält dieses Gemisch 30 bis 75 Gew.-% Essigsäure, 30 bis 75 Gew.-% Ethanol und 0 bis 20 Gew.-% Wasser. Insbesondere werden Zirkoniumium(IV)-acetylacetonat, Hexamethyldisiloxan in einem Gemisch aus Essigsäure, Ethanol und Wasser gelöst. In a preferred embodiment of the process according to the invention, one or more precursor compounds, preferably all precursor compounds, are dissolved in a mixture of acetic acid, ethanol and water. Preferably, this mixture contains 30 to 75 wt .-% acetic acid, 30 to 75 wt .-% ethanol and 0 to 20 wt .-% water. In particular, zirconium (IV) acetylacetonate, hexamethyldisiloxane are dissolved in a mixture of acetic acid, ethanol and water.
Bevorzugte apolare Lösungsmittel sind Toluol, Xylol, n-Heptan, n-Pentan, Octan, Isooctan, Cyclohexan, Methyl-, Ethyl- oder Butylacetat oder deren Gemische. Kohlenwasserstoffe oder Gemische aus Kohlenwasserstoffen mit 5 bis 15 C-Atomen sind ebenso geeignet. Insbesondere bevorzugt ist Xylol. Preferred apolar solvents are toluene, xylene, n-heptane, n-pentane, octane, isooctane, cyclohexane, methyl, ethyl or butyl acetate or mixtures thereof. Hydrocarbons or mixtures of hydrocarbons with 5 to 15 carbon atoms are also suitable. Especially preferred is xylene.
Insbesondere werden Zr(IV)-ethylhexanoat und Hexamethyldisiloxan in Xylol gelöst. In particular, Zr (IV) -ethylhexanoate and hexamethyldisiloxane are dissolved in xylene.
Die durch Spray-Pyrolyse erhaltenen Katalysatorträgerpartikel haben vorzugsweise eine spezifische Oberfläche von 36 bis 70 m2/g. The catalyst carrier particles obtained by spray pyrolysis preferably have a specific surface area of 36 to 70 m 2 / g.
Die erhaltenen Katalysatorträgerpartikel werden anschließend mit einer oder mehreren Lösungen enthaltend Verbindungen von Platin, Zinn und mindestens einem weiteren Element, ausgewählt aus Lanthan und Cäsium, imprägniert. Die imprägnierten Katalysatorträgerpartikel werden getrocknet und calciniert. The resulting catalyst support particles are then impregnated with one or more solutions containing compounds of platinum, tin and at least one other element selected from lanthanum and cesium. The impregnated catalyst support particles are dried and calcined.
Gegenstand der Erfindung ist somit auch ein Verfahren zur Herstellung von Katalysatorpartikeln umfassend Platin und Zinn sowie mindestens ein weiteres Element, ausgewählt aus Lanthan und Cäsium, auf einem Zirkondioxid enthaltenden Träger, wobei das Verfahren die Schritte (i) bis (v) und zusätzlich die Schritte The invention thus also provides a process for the preparation of catalyst particles comprising platinum and tin and at least one further element selected from lanthanum and cesium on a zirconium dioxide-containing support, the process comprising steps (i) to (v) and additionally the steps
(vi) Imprägnierung der gebildeten Katalysatorträgerpartikel mit einer oder (VI) impregnation of the catalyst support particles formed with one or
mehreren Lösungen enthaltend Verbindungen von Platin, Zinn  several solutions containing compounds of platinum, tin
und dem mindestens einen weiteren Element, ausgewählt aus Lanthan  and the at least one other element selected from lanthanum
und Cäsium, (vii) Trocknen und Calcinieren der imprägnierten Katalysatorträgerpartikel umfasst. and cesium, (vii) drying and calcining the impregnated catalyst support particles comprises.
Als Precursor-Verbindungen verwendet man in der Regel Verbindungen, die sich durch Calcinieren in die entsprechenden Oxide umwandeln lassen. Geeignet sind zum Beispiel Hydroxide, Carbonate, Oxalate, Acetate, Chloride oder gemischte Hydroxycarbonate der entsprechenden Metalle. As precursor compounds are usually used compounds which can be converted by calcination in the corresponding oxides. Suitable examples are hydroxides, carbonates, oxalates, acetates, chlorides or mixed hydroxycarbonates of the corresponding metals.
Die Aufbringung der dehydrieraktiven Komponente erfolgt in der Regel durch Tränkung. Statt durch Tränkung kann die dehydrieraktive Komponente aber auch durch andere Verfahren wie beispielsweise Aufsprühen des Metallsalzprecursors erfolgen. Bevorzugt wird Platin als H2PtCI6 oder Pt(N03)2 eingesetzt. Als Lösungsmittel eignen sich Wasser genauso wie organische Lösungsmittel. Besonders geeignet sind Wasser und niedere Alkohole wie Methanol und Ethanol. The application of the dehydrogenating component is usually carried out by impregnation. Instead of impregnation, however, the dehydrogenating component can also be carried out by other methods, such as, for example, spraying on the metal salt precursor. Platinum is preferably used as H 2 PtCl 6 or Pt (NO 3 ) 2 . Suitable solvents are water as well as organic solvents. Particularly suitable are water and lower alcohols such as methanol and ethanol.
Geeignete Precursoren bei der Verwendung von Edelmetallen als dehydrieraktive Komponente sind auch die entsprechenden Edelmetallsole, die nach einem der bekannten Verfahren, zum Beispiel durch Reduktion eines Metallsalzes in Gegenwart eines Stabilisators wie PVP mit einem Reduktionsmittel hergestellt werden können. Die Herstelltechnik wird in der deutschen Patentanmeldung DE 195 00 366 ausführlich behandelt. Suitable precursors in the use of noble metals as the dehydrogenating component are also the corresponding noble metal sols, which can be prepared by one of the known methods, for example by reduction of a metal salt in the presence of a stabilizer such as PVP with a reducing agent. The manufacturing technique is discussed in detail in the German patent application DE 195 00 366.
Der Gehalt der Katalysatoren an Platin als dehydrieraktiver Komponente beträgt 0,01 bis 5 Gew.-%, bevorzugt 0,05 bis 1 Gew.-%, besonders bevorzugt 0,05 bis 0,5 Gew.- %. The content of platinum in the catalyst as the dehydrogenating component is from 0.01 to 5% by weight, preferably from 0.05 to 1% by weight, particularly preferably from 0.05 to 0.5% by weight.
Daneben enthält der Katalysator mindestens Zinn in Mengen von 0,01 bis 10 Gew.-%, bevorzugt 0,05 bis 2 Gew.-%. Geeignete Zinnverbindungen sind Carboxylate wie Zinn(ll)acetat, Zinn-2-ethylhexanoat oder Zinn(ll)chlorid. In addition, the catalyst contains at least tin in amounts of 0.01 to 10 wt .-%, preferably 0.05 to 2 wt .-%. Suitable tin compounds are carboxylates such as tin (II) acetate, tin 2-ethylhexanoate or tin (II) chloride.
In einer bevorzugten Ausführungsform beträgt die Beladung mit Pt 0,05 bis 1 Gew.-% und die Beladung mit Sn 0,05 bis 2 Gew.-%. In a preferred embodiment, the loading with Pt is 0.05 to 1 wt .-% and the loading with Sn 0.05 to 2 wt .-%.
Weiterhin kann die Aktivmasse folgende weitere Komponenten enthalten, wobei mindestens Cäsium oder Lanthan enthalten sind: Furthermore, the active composition may contain the following further components, wherein at least cesium or lanthanum are contained:
Cäsium und gegebenenfalls Kalium mit einem Gehalt zwischen 0,1 und 10 Gew.- %. Als Cäsium- bzw. Kalimoxidprecursoren verwendet man Verbindungen, die sich durch Calcinieren in die Oxide umwandeln lassen, beispielsweise die Hydroxide, Car- bonate, Oxalate, Acetate oder Formiate. Cesium and optionally potassium with a content between 0.1 and 10% by weight. As cesium or Kalimoxidprecursoren using compounds that are can be converted by calcination in the oxides, for example, the hydroxides, carbonates, oxalates, acetates or formates.
Lanthan und gegebenenfalls Cer mit einem Gehalt zwischen 0,1 und 10 Gew.-%. Wird Lanthan verwendet, so sind als Precursorsalze beispielsweise Lanthanoxidcarbonat, La(OH)3, La2(C03)3, La(N03)3, Lanthanformiat, Lanthanacetat und Lanthanoxalat geeignet. Lanthanum and optionally cerium with a content between 0.1 and 10 wt .-%. If lanthanum is used, the precursor salts suitable are, for example, lanthanum oxide carbonate, La (OH) 3 , La 2 (CO 3 ) 3, La (NO 3 ) 3, lanthanum formate, lanthanum acetate and lanthanum oxalate.
Nach dem Aufbringen der Aktivkomponenten auf den Katalysatorträger erfolgt die Calcinierung bei Temperaturen von 400 bis 1000°C, bevorzugt von 500 bis 700°C, besonders bevorzugt bei 550 bis 650°C. After the application of the active components on the catalyst support, the calcination takes place at temperatures of 400 to 1000 ° C, preferably from 500 to 700 ° C, more preferably at 550 to 650 ° C.
Gegenstand der vorliegenden Erfindung sind auch die mit dem erfindungsgemäßen Verfahren erhältlichen Träger und Katalysatorpartikel. Diese haben vorzugsweise eine spezifische Oberfläche von 20 bis 70 m2/g. The present invention also provides the carrier and catalyst particles obtainable by the process according to the invention. These preferably have a specific surface area of 20 to 70 m 2 / g.
In einer bevorzugten Ausführungsform weisen die Katalysatorträger folgende prozentuale Zusammensetzung auf: 30 bis 99,5 Gew.-% Zr02, 0,5 bis 25 Gew.-% Si02. Die Katalysatorpartikel enthalten weiterhin 0,1 bis 1 Gew.-% Pt, 0,1 bis 10 Gew.-% Sn, La und/oder Cs, bezogen auf die Masse des Trägers, wobei mindestens Sn und mindestens La oder Cs enthalten sind. In a preferred embodiment, the catalyst supports have the following percentage composition: 30 to 99.5% by weight Zr0 2 , 0.5 to 25% by weight Si0 2 . The catalyst particles further contain 0.1 to 1 wt .-% Pt, 0.1 to 10 wt .-% Sn, La and / or Cs, based on the mass of the carrier, wherein at least Sn and at least La or Cs are included.
Gegenstand der vorliegenden Erfindung ist auch die Verwendung der Katalysatorpartikel als Hydrierkatalysatoren oder Dehydrierkatalysatoren. Bevorzugt dehydriert werden Alkane, wie Butan und Propan, aber auch Ethylbenzol. The present invention also relates to the use of the catalyst particles as hydrogenation catalysts or dehydrogenation catalysts. Alkanes, such as butane and propane, but also ethylbenzene are preferably dehydrated.
Besonders bevorzugt ist die Verwendung der erfindungsgemäßen Katalysatoren zur Dehydrierung von Propan zu Propen. Particularly preferred is the use of the catalysts of the invention for the dehydrogenation of propane to propene.
Die Erfindung wird durch das nachstehende Beispiel näher erläutert. Beispiel The invention is further illustrated by the following example. example
Verwendete Chemikalien Used chemicals
Zirkoniumacetylacetonate Zr(acac)2 (98 %) Zirconium acetylacetonates Zr (acac) 2 (98%)
Zirkoniumium(IV)-propoxid Zr(OPr)4 (70 % in 1 -Propanol) Zirconium (IV) -propoxide Zr (OPr) 4 (70% in 1-propanol)
Hexamethyldisiloxan (HMDSO) (98 %)  Hexamethyldisiloxane (HMDSO) (98%)
CsN03 CsN0 3
KN03 SnCI2 · 2 H20 KN0 3 SnCl 2 · 2H 2 0
La(N03)3 · 6 H20 La (NO 3 ) 3 .6H 2 0
Gemisch aus Essigsäure (100 %), Ethanol (96%) und Wasser (entionisiert)  Mixture of acetic acid (100%), ethanol (96%) and water (deionized)
Xylol (Isomerengemisch) Xylene (mixture of isomers)
Herstellung der Lösungen der Vorläuferverbindungen Preparation of solutions of precursor compounds
Das Lösungsmittel ist HoAc : EtOH : H20 im Masse-Verhältnis 4,6 zu 4,6 zu 1. Das Es- sigsäure-Ethanol-Gemisch wird frisch hergestellt. Darin löst man die Vorläuferverbindungen für Si und Zr. Alternativ wird Xylol verwendet. The solvent is HoAc: EtOH: H 2 O in the mass ratio 4.6 to 4.6 to 1. The acetic acid-ethanol mixture is freshly prepared. This dissolves the precursor compounds for Si and Zr. Alternatively, xylene is used.
Tabelle 1 : Zusammensetzungen der Lösungen der Vorläuferverbindungen für apolaren Table 1: Compositions of solutions of precursor compounds for apolar
Ansatz (Xylol)  Approach (xylene)
Herstellung der Katalvsatorträgerpartikel durch Flammen-Spravpyrolvse Preparation of the catalyst carrier particles by flame spraying
Die Lösung enthaltend die Vorläuferverbindungen wurde mit Hilfe einer Kolbenpumpe über eine Zweistoff-Düse zugeführt und mit einer entsprechenden Menge an Luft verdüst. Um die entsprechenden Temperaturen zu erreichen, wurde teilweise eine Stützflamme aus einem Ethylen-Luft-Gemisch, welches über einen um die Düse befindlichen Ringbrenner dosiert wurde, verwendet. Der Druckabfall wurde konstant bei 1 ,1 bar gehalten. The solution containing the precursor compounds was fed by means of a piston pump via a two-fluid nozzle and sprayed with an appropriate amount of air. In order to reach the appropriate temperatures, a support flame was partially used from an ethylene-air mixture, which was metered via a ring burner located around the nozzle. The pressure drop was kept constant at 1, 1 bar.
In Tabelle 2 sind die Flammensynthese-Bedingungen zusammengefasst. Table 2 summarizes the flame synthesis conditions.
Tabelle 2: Versuchsparameter Trägern aus der Flammensprühpyrolyse Table 2: Experimental parameters carriers from flame spray pyrolysis
Lösungsmittel Czr Vorläufer- Gasamtgasfluss Dispersiongasfluss Solvent Czr Precursor Gas Velocity Gas Flow Dispersion Gas Flow
[mol/kg verbidungsfluss [l/h] [l/h] [mol / kg binding flux [l / h] [l / h]
Lösung] [ml/h] Solution] [ml / h]
Xylol 1 310 3500 1200 Zur Abscheidung der Partikel wurde ein Baghousefilter verwendet. Zum Abreinigen dieser Filter konnten die Filtersäcke mit 5 bar Druckstößen von Stickstoff beaufschlagt werden. Xylene 1 310 3500 1200 A baghouse filter was used to separate the particles. To clean these filters, the filter bags were subjected to 5 bar pressure surges of nitrogen.
Imprägnierung des flammensynthetisierten Trägers Impregnation of the flame-synthesized carrier
Die Imprägnierung wurde entsprechend Beispiel 4 der EP 1 074 301 durchgeführt. Der flammensynthetisierte Si02/Zr02-Träger der Siebfraktion 1 - 2 mm wurde mit einer Lösung von SnCI2 und H2PtCI6 in Ethanol Übergossen. Die überschüssige Lösung wurde im Rotationsverdampfer entfernt, der Feststoff getrocknet und calciniert. Dazu wurde eine wässrige Lösung aus CsN03 und La(N03)3 gegeben und der Überstand entfernt. Der Katalysator wurde nach Trocknung und Calcinieren mit einer BET- Oberfläche von 23 m2 erhalten. The impregnation was carried out according to Example 4 of EP 1 074 301. The flame-synthesized Si0 2 / Zr0 2 support of the 1 to 2 mm sieve fraction was poured over a solution of SnCl 2 and H 2 PtCl 6 in ethanol. The excess solution was removed on a rotary evaporator, the solid dried and calcined. An aqueous solution of CsN0 3 and La (NO 3 ) 3 was added thereto and the supernatant was removed. The catalyst was obtained after drying and calcining with a BET surface area of 23 m 2 .
Referenzkatalysator reference catalyst
Der Referenzkatalysator nach EP 1 074 301 besteht aus 95 Gew.-% Zr02, 5 Gew.-% Si02 (Träger), 0,5 Gew.-% Pt, 1 Gew.-% Sn, 3 % La, 0,5 Gew.-% Cs und 0,2 Gew.-% K (Aktiv- und Promotormetalle bezogen auf die Masse des Trägers), hergestellt nach Beispiel 4 auf nasschemischem Wege. Der Träger wurde durch Sprühtrocknung des nach dem Sol/Gel-Verfahren durch Fällung erhaltenen Oxidgemischs hergestellt. The reference catalyst according to EP 1 074 301 consists of 95% by weight Zr0 2 , 5% by weight Si0 2 (carrier), 0.5% by weight Pt, 1% by weight Sn, 3% La, 0, 5 wt .-% Cs and 0.2 wt .-% K (active and promoter metals based on the mass of the carrier) prepared according to Example 4 by wet-chemical means. The support was prepared by spray-drying the oxide mixture obtained by precipitation by the sol / gel process.
Katalvtische Messungen Catalvian measurements
Die Propandehydrierung wurde bei ca. 600 °C durchgeführt. 21 Nl/h Gesamtgas (20 Nl/h Propan, 1 Nl/h Stickstoff als Interner Standard), 5 g/h Wasser. Die Regeneration wird bei 400 °C vorgenommen: 2 Stunden 21 Nl/h N2 + 4 Nl/h Luft; 2 Stunden 25 Nl/h Luft; 1 Stunde 25 Nl/h Wasserstoff. The propane dehydrogenation was carried out at about 600 ° C. 21 Nl / h of total gas (20 Nl / h of propane, 1 Nl / h of nitrogen as internal standard), 5 g / h of water. The regeneration is carried out at 400 ° C: 2 hours 21 Nl / h N 2 + 4 Nl / h air; 2 hours 25 Nl / h air; 1 hour 25 Nl / h of hydrogen.
In den katalytischen Tests wurde der Umsatz, die Langzeitstabilität sowie die Selektivität der Propenbildung untersucht. Der erhaltene Katalysator aus der Flammensynthese mit anschließender Tränkung zeigte bei optimalem Betriebszustand 48 % Umsatz sowie 95 % Selektivität in der autothermen Dehydrierung von Propan zu Propen. In the catalytic tests, the conversion, the long-term stability and the selectivity of propene formation were investigated. The resulting catalyst from the flame synthesis with subsequent impregnation showed 48% conversion and 95% selectivity in the autothermal dehydrogenation of propane to propene at optimum operating state.
Figur 1 zeigt zum Vergleich die Aktivitäten und Selektivitäten des Referenzkatalysators (-) mit durch Fällung und Sprühtrocknung hergestelltem Träger und des erfindungsgemäßen Katalysators, dessen Träger aus der Flammensynthese stammt (■), wobei die weiteren Elemente jeweils durch Tränkung aufgebracht wurden. Die Ergebnisse für einen ausschließlich flammensynthetisierten Katalysators gleicher Zusammensetzung ( A ) sind ebenfalls gezeigt. Auf der Abszisse ist die Zeit in Stunden aufgetragen, auf der Ordinate sind Umsätze (40 bis 50 %) und Selektivitäten (> 80 %) für die autother- me Dehydrierung von Propan zu Propen aufgetragen. FIG. 1 shows for comparison the activities and selectivities of the reference catalyst (-) with support prepared by precipitation and spray-drying and the catalyst according to the invention whose support originates from the flame synthesis (■), the other elements being applied in each case by impregnation. The results for a flame-only synthesized catalyst of the same composition (A) are also shown. The abscissa shows the time in hours the ordinate shows conversions (40 to 50%) and selectivities (> 80%) for the autothermal dehydrogenation of propane to propene.
Es zeigt sich eine vergleichbare Performance der drei Katalysatoren. Der Referenz- Katalysator weist geringere Anfangsselektivitäten auf. Über die Versuchszyklen einiger Wochen gleicht er sich jedoch an. Somit verhalten sich der flammensynthetisierte Katalysator und der flammensynthetisierte Träger nach nasschemischer Aufbringung der weiteren Elemente (erfindungsgemäß) wie ein gealterter Katalysator, der dessen Träger durch Sprühtrocknung hergestellt wurde. It shows a comparable performance of the three catalysts. The reference catalyst has lower initial selectivities. However, it is similar to the test cycles of a few weeks. Thus, the flame-synthesized catalyst and the flame-synthesized carrier after wet-chemical application of the other elements (according to the invention) behave like an aged catalyst whose carrier was prepared by spray-drying.

Claims

Patentansprüche claims
1. Verfahren zur Herstellung von Katalysatorträgerpartikeln, enthaltend Zirkondioxid und optional Siliciumoxid, umfassend die Schritte A process for the preparation of catalyst support particles containing zirconia and optionally silica, comprising the steps
(i) Bereitstellung einer Lösung enthaltend mindestens eine Vorläuferverbindung von Zirkondioxid und optional von Siliciumdioxid, (i) providing a solution containing at least one precursor compound of zirconium dioxide and optionally of silica,
(ii) Überführung der Lösung(en) in ein Aerosol,  (ii) transfer of the solution (s) into an aerosol,
(iii) Einbringen des Aerosols in eine direkt oder indirekt beheizte Pyrolysezone, (iii) introducing the aerosol into a directly or indirectly heated pyrolysis zone,
(iv) Durchführung der Pyrolyse, (iv) carrying out the pyrolysis,
(v) Abscheidung der gebildeten Katalysatorpartikel aus dem Pyrolysegas.  (V) deposition of the catalyst particles formed from the pyrolysis gas.
2. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, dass die Pyrolysezone durch eine Flamme beheizt wird. 2. The method according to claim 1, characterized in that the pyrolysis zone is heated by a flame.
3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass die Zirkondioxid- Vorläuferverbindung Zirkon(IV)-ethylhexanoat umfasst. 3. The method according to claim 1 or 2, characterized in that the zirconia precursor compound comprises zirconium (IV) ethylhexanoate.
4. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass die Siliciumdioxid-Vorläuferverbindung Hexamethyldisiloxan umfasst. 4. The method according to any one of claims 1 to 3, characterized in that the silica precursor compound comprises hexamethyldisiloxane.
5. Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass die Zirkondioxid-Vorläuferverbindung Zirkon(IV)-propoxylat umfasst. 5. The method according to any one of claims 1 to 4, characterized in that the zirconia precursor compound comprises zirconium (IV) propoxylate.
6. Verfahren nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass eine oder mehrere der Vorläuferverbindungen in einem Gemisch aus Essigsäure, Ethanol und Wasser gelöst sind. 6. The method according to any one of claims 1 to 5, characterized in that one or more of the precursor compounds are dissolved in a mixture of acetic acid, ethanol and water.
7. Verfahren nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass eine oder mehrere der Vorläuferverbindungen in Xylol gelöst sind. 7. The method according to any one of claims 1 to 6, characterized in that one or more of the precursor compounds are dissolved in xylene.
8. Verfahren nach einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, dass die Pyrolyse bei einer Temperatur von 900 bis 1500 °C durchgeführt wird. 8. The method according to any one of claims 1 to 7, characterized in that the pyrolysis is carried out at a temperature of 900 to 1500 ° C.
9. Katalysatorträgerpartikel erhältlich durch das Verfahren nach einem der Ansprüche 1 bis 8. 9. Catalyst carrier particles obtainable by the process according to one of claims 1 to 8.
10. Verfahren zur Herstellung von Katalysatorpartikeln, umfassend Platin und Zinn sowie mindestens ein weiteres Element, ausgewählt aus Lanthan und Cäsium auf einem Zirkondioxid enthaltenden Träger, umfassend die Schritte (i) bis (v) gemäß einem der Ansprüche 1 bis 8, und zusätzlich die Schritte 10. A process for the preparation of catalyst particles comprising platinum and tin and at least one further element selected from lanthanum and cesium on a zirconium dioxide-containing carrier, comprising the steps (i) to (v) according to one of claims 1 to 8, and additionally steps
(vi) Imprägnierung der gebildeten Katalysatorträgerpartikel mit einer oder (VI) impregnation of the catalyst support particles formed with one or
mehreren Lösungen enthaltend Verbindungen von Platin, Zinn  several solutions containing compounds of platinum, tin
und dem mindestens einem weiteren Element, ausgewählt aus Lanthan und Cäsium,  and the at least one further element selected from lanthanum and cesium,
(vii) Trocknen und Calcinieren der imprägnierten Katalysatorträgerpartikel.  (vii) drying and calcining the impregnated catalyst carrier particles.
1 1. Katalysatorpartikel erhältlich durch das Verfahren nach Anspruch 10. 1 1. Catalyst particles obtainable by the method according to claim 10.
12. Katalysatorpartikel nach Anspruch 11 , dadurch gekennzeichnet, dass sie 0,05 bis 1 Gew.-% Pt und 0,05 bis 2 Gew.-% Sn enthalten. 12. Catalyst particles according to claim 11, characterized in that they contain 0.05 to 1 wt .-% Pt and 0.05 to 2 wt .-% Sn.
13. Katalysatorpartikel nach Anspruch 1 1 oder 12 mit einer spezifische Oberfläche von 20 bis 70 m2/g. 13. Catalyst particles according to claim 1 1 or 12 having a specific surface area of 20 to 70 m 2 / g.
14. Katalysatorpartikel nach einem der Ansprüche 11 bis 13, umfassend 30 bis 99,5 Gew.-% Zr02, 0,5 bis 25 Gew.-% Si02 als Träger und 0,1 bis 1 Gew.-% Pt, 0,1 bis 10 Gew.-% Sn, La und/oder Cs, bezogen auf die Masse des Trägers, wobei mindestens Sn und mindestens La oder Cs enthalten sind. 14. A catalyst particle according to any one of claims 11 to 13, comprising 30 to 99.5 wt .-% Zr0 2 , 0.5 to 25 wt .-% Si0 2 as a carrier and 0.1 to 1 wt .-% Pt, 0 , 1 to 10 wt .-% Sn, La and / or Cs, based on the mass of the carrier, wherein at least Sn and at least La or Cs are included.
15. Verwendung der Katalysatorpartikel nach einem der Ansprüche 1 1 bis 14 als Dehydrierkatalysator. 15. Use of the catalyst particles according to any one of claims 1 to 1 14 as dehydrogenation catalyst.
16. Verwendung nach Anspruch 15 der Katalysatorpartikel zur Dehydrierung von Propan zu Propen oder von Butan zu Buten. 16. Use according to claim 15 of the catalyst particles for the dehydrogenation of propane to propene or of butane to butene.
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