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WO1999008785A2 - Membranes en oxyde d'aluminium nano-poreuses contenant des clathrates de metaux precieux ou des nanoparticules de metaux precieux - Google Patents

Membranes en oxyde d'aluminium nano-poreuses contenant des clathrates de metaux precieux ou des nanoparticules de metaux precieux Download PDF

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Publication number
WO1999008785A2
WO1999008785A2 PCT/EP1998/004863 EP9804863W WO9908785A2 WO 1999008785 A2 WO1999008785 A2 WO 1999008785A2 EP 9804863 W EP9804863 W EP 9804863W WO 9908785 A2 WO9908785 A2 WO 9908785A2
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WO
WIPO (PCT)
Prior art keywords
noble metal
clusters
nano
nanoparticles
pore radius
Prior art date
Application number
PCT/EP1998/004863
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German (de)
English (en)
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WO1999008785A3 (fr
Inventor
Alfred Hagemeyer
Harald Werner
Uwe Dingerdissen
Klaus KÜHLEIN
Günter Schmid
Original Assignee
Celanese Chemicals Europe Gmbh
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Publication date
Application filed by Celanese Chemicals Europe Gmbh filed Critical Celanese Chemicals Europe Gmbh
Publication of WO1999008785A2 publication Critical patent/WO1999008785A2/fr
Publication of WO1999008785A3 publication Critical patent/WO1999008785A3/fr

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Classifications

    • 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
    • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
    • B01J35/58—Fabrics or filaments
    • B01J35/59—Membranes
    • 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
    • B01J35/40—Catalysts, in general, characterised by their form or physical properties characterised by dimensions, e.g. grain size
    • B01J35/45—Nanoparticles
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C67/00—Preparation of carboxylic acid esters
    • C07C67/04—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides onto unsaturated carbon-to-carbon bonds
    • C07C67/05—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides onto unsaturated carbon-to-carbon bonds with oxidation
    • C07C67/055—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides onto unsaturated carbon-to-carbon bonds with oxidation in the presence of platinum group metals or their compounds
    • 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

Definitions

  • the invention relates to precious metal supported catalysts, namely nano-porous aluminum oxide membranes containing precious metal clusters, processes for their production and the use thereof, in particular as a supported catalyst for vinyl acetate synthesis.
  • Precious metal catalysts have long been known per se and are widely used for numerous technical heterogeneously catalyzed oxidation and hydrogenation reactions.
  • the supported catalysts are produced by applying metal salt solutions (for example chlorides, nitrates, acetates) to the (for example oxide-ceramic) support and then reducing them with chemical reducing agents to the metals in oxidation state 0.
  • the noble metal atoms agglomerate to ia non-uniform precious metal particles with a broad particle size distribution.
  • the diameters of the nanoparticles often range from 1 to 100 nm.
  • the non-uniform size distribution of the catalytically active component has an unfavorable effect on the activity and selectivity of the catalysts.
  • the long-term behavior (“service life") of the catalysts is often unsatisfactory, since the nanoparticles are mobile on the support and grow together over time through sintering to form larger aggregates with little activity, so that the catalysts deactivate relatively quickly.
  • An improvement in the production of precious metal supported catalysts was represented by the brine impregnation technology, in which (by chemical reduction of metal salt solutions) pre-formed nanoparticles (oxidation level 0) are drawn onto the support from colloidal solution. To avoid agglomeration of the nanoparticles in solution and their precipitation, the nanoparticles are stabilized with ligands. Each nanoparticle is surrounded by a protective ligand that prevents direct contact between the metal nuclei and thereby keeps the nanoparticles in solution.
  • a major advantage of the sol coating technology is that the precious metal components are essentially already in a reduced state after the sol has been applied to the carrier. This eliminates a reduction in the active metals at high temperatures, which generally causes the noble metals to sinter together and thereby reduces the catalytic surface.
  • the prior art teaches methods for producing heterogeneous catalysts which are characterized in that nanoparticles of one or more catalytically active metals are first produced in a separate process step via a sol process and these particles are then immobilized on a support.
  • the general advantage of the sol process is the achievable dispersity of the particles and the narrow distribution of the particle diameters.
  • stabilizers or ligands are used to stabilize the metal particles
  • Stabilizers or protective colloids envelop the metal particles.
  • the ligands can be both neutral and have an electrical charge. This prevents the particles from clumping together.
  • low molecular weight stabilizers include oxygen-, phosphorus-, sulfur- or nitrogen-containing ligands as well as cationic, anionic, betaine or non-ionic surfactants.
  • Process for the production of hydrosols and organosols of, for example, palladium and Gold has been described several times, as have heterogeneous catalysts produced from it: YLLam and M.
  • EPA 0 672 765 claims the electrochemical production of i.a. Pd / Au sols using cationic, anionic, nonionic or betaine stabilizers.
  • the metal salts are reduced on the cathode of an undivided electrolysis cell.
  • the betaine-stabilized brines described there require an approximately 5-fold molar excess of stabilizer, based on the metal salt and the use of organic solvents.
  • DE 4443 701 claims shell catalysts which are said to be suitable as heterogeneous catalysts.
  • the particles are deposited in an outer shell of the carrier grain that is up to 200 nanometers thick.
  • a process for their production by means of a cation-stabilized hydrosol is also claimed.
  • DE-A-195 00 366 describes the production of Pd shell catalysts for Hydrogenation by applying the Pd as a highly diluted sol by impregnation or spraying on a support, resulting in a shell thickness of less than 5000 nanometers.
  • PVP is used as a stabilizer.
  • the sol-impregnated catalysts often have a lower activity than the conventional catalysts. Sometimes this can be compensated for by a greatly increased metal load.
  • the cause of the loss of activity lies in the too tightly adhering ligand shell, by which the nanoparticles are still surrounded after the carrier fixation and which block the active centers on the metal surface. Attempts to remove the disruptive ligand shell by extraction with solvents were unsuccessful, since large parts of the nanoparticles were washed off the support again and the ligand shell could only be removed incompletely. Only a part of the ligand molecule can be removed by hydrolysis of the ligands, the head group of the ligand adhering to the metal surface remains on the nanoparticle.
  • the nanoparticles sinter at the necessary high combustion temperatures to form larger aggregates with a non-uniform size distribution, so that the original advantage of the sol impregnation technology is nullified.
  • the object of the invention is to provide supported noble metal catalysts which are particularly suitable for oxidation and hydrogenation reactions, which have ligand-free nanoparticles with a uniform composition and narrow particle size distribution and which are characterized by high activities and Characterize selectivity and which are particularly stable against the effects of higher temperatures and are characterized by long-term stability.
  • noble metal clusters or nanoporous aluminum oxide membranes containing noble metal nanoparticles with a narrow pore radius distribution are preferably 1-500 nm and preferably has a standard deviation of the pore radius distribution of 0-20, preferably 0-10%.
  • the noble metal clusters or noble metal nanoparticles advantageously consist of palladium, platinum or binary metal alloys such as palladium-gold alloys.
  • the invention further relates to a process for the production of noble metal clusters or nanoporous aluminum oxide membranes containing noble metal nanoparticles, which is characterized in that nanoporous alumina membranes obtained with anodic oxidation and having a narrow pore radius distribution are coated with a colloidal solution of ligands, stabilized noble metal nanoparticles or clusters, dried and then in Calcined in the presence of an oxygen-containing gas.
  • the caicination advantageously takes place in the presence of air.
  • the caicination is carried out in the presence of pure oxygen.
  • Another advantageous embodiment involves calcining in the presence of ozone.
  • the caicination is preferably carried out at temperatures of 50-1200, in particular at 100-1000, particularly advantageously at temperatures of 200-1000X. It is advantageous to use aluminum oxide membranes with an average pore radius of 1-500nm and a standard deviation of
  • Pore radius distribution from 0-20%, preferably from 0-10% to use. It is advantageous to carry out the coating with monodisperse nanoparticles or clusters.
  • Palladium, platinum, binary noble metal alloys such as palladium-gold alloys are particularly suitable as noble metals in the context of the invention.
  • Another object of the invention is the use of palladium-gold noble metal clusters or gold-palladium nanoparticles containing nanoporous Aluminum oxide membranes as a catalyst for the synthesis of vinyl acetate
  • Nanoporous Alumina (Alum ⁇ na) membranes with very narrow r pore distribution can be produced by anodic oxidation of Aluminiurnoberfiachen in acidic particular diprotic acids such as sulfuric acid, oxalic acid or t ⁇ protician acids such as phosphoric acid at temperatures around 0 ° C
  • diprotic acids such as sulfuric acid, oxalic acid or t ⁇ protician acids
  • phosphoric acid at temperatures around 0 ° C
  • the anodizing takes place under precise potential and current control.
  • the pore diameter in the membrane depends directly on the applied voltage The result is a pore size of 1.4 nm per volt.
  • the pore density can vary between 10 9 to 10 12 / cm 2.
  • the variation of the pore size ranges from 1 to 500 nm.
  • the thickness of the membrane depends on the anodizing time and can be up to about 500 mm or more, for example 600 - 1000 mm.
  • Such nanoporous alumina films show excellent thermal properties
  • the resulting polymorphic starting material produces over 300 ° C g and over 800 ° C aluminum oxide.
  • the pore diameter widens somewhat, while the size of the membrane shrinks somewhat, so that the overall porosity increases
  • the surfaces of the aluminum oxide membranes can be chemically modified because they are covered with OH groups. This devatization can be used
  • Aluminum membranes can be used in various forms: a) with a closed and an open side b) with an open and semi-open side, i.e. smaller pore openings and c) bilateral pore opening.
  • the closed or semi-open side facing the aluminum is called the barrier side, the other, open, solution side.
  • Metal clusters can be inserted into the pores in various ways.
  • Vacuum induction Metal clusters and colloids can be brought into the pores from solution by applying a vacuum to one side of the membrane.
  • membrane type b) is used so that the particles get stuck in the narrowed 1-2nm pores and do not leave the pore with the solution.
  • Electrophoresis The prerequisite is that the clusters used move in an electric field, which was observed in all cases examined.
  • One side of the membrane is contacted with a metal. It can original aluminum. If the membrane has previously been detached from the aluminum, one side can subsequently be steamed or sputtered with metal. The method also works in the presence of the
  • FIG. 2 schematically shows the arrangement for the electrophoretic filling of pores.
  • Oxygen, or from (-) - chinchonidine and oxygen according to G.Schmid, M.Harms, J.-O.Malm, J.-O.Bovin, J.v. Ruitenbeck, H.W. Zandbergen, Wen T.Fu, J. Am. Chem. Soc. 115 (1993) 2046; G. Schmid, S. Emde, V. Maihack, W. Meyer-Zaika, St. Peschel, J. Mol Catal. A 107 (1996) 95; G. Schmid, V. Maihack, F. Lantermann, St. Peschel, J. Chem. Soc. Dalton Trans. (1996) 589.
  • Fig. 3 shows 18-20nm created from originally 1.5nm clusters Particles.
  • noble metal supported catalysts with a uniform particle size of the noble metal nanoparticles can optionally be loaded with further promoters and dopants and can be used for oxidation and hydrogenation reactions.
  • Clusters of different metals can be filled in during thermolysis e.g. also produce bimetallic particles.
  • Pd-Au bimetal supported catalysts produced by the method according to the invention are particularly suitable for the synthesis of vinyl acetate by gas phase oxidation of ethylene and acetic acid.
  • the catalytic conversion of ethylene, oxygen and acetic acid to vinyl acetate, the starting monomer of an economically important group of polymers, is carried out on an industrial scale in tube bundle reactors in the gas phase.
  • the heterogeneous catalysts used for this purpose contain as a catalytically active component palladium and possibly gold-containing particles which are immobilized on an inert carrier material.
  • heterogeneous catalysts consist of an inert, porous support material such as moldings, bulk material or powder and the catalytically active components which are located on the surface and in the pores of the support material.
  • the catalytically active components When producing such catalysts, it is important to form as many active centers as possible, i.e. to apply the catalytically active components in fine distribution to the support and to anchor them as firmly as possible on the outer and inner surface of the support at the locations which are accessible to the reactants.
  • the reactive centers are produced by applying a solution of compounds of the catalytically active components to the support, for example by impregnation with a solution of salts of the metals in question.
  • the compounds on the support are then converted into the catalytically active components by one or more chemical steps, for example by precipitation and reduction.
  • the particle diameters that can be achieved are above 10-20 nanometers. There is usually a relatively broad distribution of particle diameters of around 5 to 100 nanometers. The formation of larger metal particles of a few 100 to 200 nanometers is particularly undesirable. This results in a reduction in the catalytic activity infoige the reduction in the specific metal surface.
  • a cluster simplified as a cube, which consists of atoms of a metal with an assumed diameter of 0.25 nanometers, contains approximately 87% with an edge length of 1 nanometer, with one
  • the carrier often contains gold-rich domains next to districts with a balanced Pd / Au ratio.
  • An uneven distribution is one of the possible causes during the loading process and a different behavior during the fixing process.
  • supported noble metal catalysts under the usual operating conditions, i.e. loss of activity at temperatures of around 150 to 170 ° C for longer periods of operation. This loss is due among other things that the metal particles migrate on the support surface and can unite with other particles, i.e. recrystallize to form larger particles, resulting in a reduction in specific surface area. The smaller the metal particles, the more pronounced this effect. Since corresponding observations have also been made with vinyl acetate catalysts, it is desirable to reduce the rate of migration of the palladium-gold particles by embedding them in a microenvironment which interacts more intensely with the support.
  • the task was therefore to develop new Pd / Au catalysts with improved properties. their particle size, particle distribution, composition and microstructure and improved service life (long-term behavior).
  • the use of conventional brine watering technology cannot solve the problems mentioned satisfactorily.
  • the low molecular weight or polymeric compounds previously used as stabilizers or protective colloids for the preformed nanoparticles have various disadvantages.
  • the ligand stabilizers impair, for example, due to the strong interactions of their donor groups with the active metal centers catalytic interactions. For the same reason, it is difficult to separate them from the metal core after they have been applied to a carrier.
  • Polymeric protective colloids can impair the catalytic activity of the metal particles, so that their removal after fixation is desirable. In many cases this does not succeed or only incompletely.
  • bimetallic supported Pd / Au catalysts with improved properties can be obtained. their particle size, particle distribution, composition and microstructure and improved service life (long-term behavior).
  • the carrier Before, during and / or after the fixing of the brine and / or the caicination, the carrier can also be combined with further activators, in particular alkali acetates, preferably K acetate and optionally promoters, for example Zr, Ti, Cd, Ba, Cu connections.
  • further activators in particular alkali acetates, preferably K acetate and optionally promoters, for example Zr, Ti, Cd, Ba, Cu connections.
  • the metal contents of the finished catalysts have the following values:
  • the Pd content of the Pd / Au catalysts is generally 0.5 to 2.0% by weight, preferably 0.6 to 1.5% by weight.
  • the Au content of the Pd / Au catalysts is generally 0.2 to 1.0% by weight, preferably 0.3 to 0.8% by weight.
  • a preferred catalyst system also contains K acetate as an activator.
  • the K content is generally 0.5 to 4.0% by weight, preferably 1.5 to 3.0% by weight.
  • the vinyl acetate is generally prepared by passing gases containing acetic acid, ethylene and oxygen or oxygen at from 100 to 220 ° C., preferably from 120 to 200 ° C., and from 1 to 25 bar, preferably from 1 to 20 bar, over the finished catalyst, whereby unreacted components can be circulated.
  • the oxygen concentration is expediently kept below 10% by volume (based on the acetic acid-free Gas mixture).
  • Gases such as nitrogen or carbon dioxide are beneficial. Carbon dioxide is particularly suitable for dilution since it is formed in small quantities during the reaction.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Catalysts (AREA)

Abstract

L'invention concerne des membranes en oxyde d'aluminium nano-poreuses contenant des clathrates de métaux précieux ou bien des nanoparticules de métaux précieux, ces membranes ayant été obtenues par oxydation anodique et présentant une distribution serrée des rayons des pores. La fabrication s'effectue par revêtement des membranes avec une solution colloïdale de nanoparticules ou de clathrates de métaux précieux stabilisés avec des ligands, séchage et ensuite calcination en présence d'un gaz contenant de l'oxygène. Ces membranes en oxyde d'aluminium présentent un rayon de pore moyen de 1-500 nm avec un écart type de la distribution des rayons des pores de 0-20 %, de préférence de 0-10%. Ces membranes en oxyde d'aluminium contenant des clathrates ou des nanoparticules de métaux précieux conviennent notamment comme catalyseurs lors de la synthèse en présence d'acétate de vinyle.
PCT/EP1998/004863 1997-08-13 1998-08-05 Membranes en oxyde d'aluminium nano-poreuses contenant des clathrates de metaux precieux ou des nanoparticules de metaux precieux WO1999008785A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19734973A DE19734973A1 (de) 1997-08-13 1997-08-13 Edelmetallcluster enthaltende nano-poröse Aluminium-oxid-Membranen
DE19734973.0 1997-08-13

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WO1999008785A2 true WO1999008785A2 (fr) 1999-02-25
WO1999008785A3 WO1999008785A3 (fr) 1999-05-27

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001054216A3 (fr) * 2000-01-18 2002-02-21 Univ Ramot Pile a combustible a membrane conductrice de protons
US6447943B1 (en) 2000-01-18 2002-09-10 Ramot University Authority For Applied Research & Industrial Development Ltd. Fuel cell with proton conducting membrane with a pore size less than 30 nm
WO2003046265A3 (fr) * 2001-11-26 2003-11-13 Massachusetts Inst Technology Production de films epais d'alumine anodique poreuse et de reseaux de nanocables sur un substrat solide
US7472576B1 (en) 2004-11-17 2009-01-06 State Of Oregon Acting By And Through The State Board Of Higher Education On Behalf Of Portland State University Nanometrology device standards for scanning probe microscopes and processes for their fabrication and use

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4654083B2 (ja) * 2005-07-20 2011-03-16 富士フイルム株式会社 金属粒子型反応触媒およびその製造方法、並びに該触媒を用いた有機合成反応装置
JP4769595B2 (ja) 2005-08-12 2011-09-07 富士フイルム株式会社 重合体、該重合体を含有する膜形成用組成物、該組成物を用いて形成した絶縁膜及び電子デバイス
DE102005044913A1 (de) * 2005-09-20 2007-03-22 Technische Universität Darmstadt Verfahren zur selektiven Herstellung von Dihydroxyaceton aus Glycerin sowie ein Verfahren zur Herstellung eines Metallkatalysators zur selektiven Oxidation von Glycerin
DE102014003508A1 (de) * 2014-03-14 2015-09-17 Airbus Defence and Space GmbH Verfahren zur Herstellung sowie Verwendung einer polierten nanostrukturierten metallischen Oberfläche mit wasser- und eisabweisenden Eigenschaften

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS514118A (en) * 1974-06-27 1976-01-14 Kuraray Co Sakusanbiniruno seizohoho
JPH04122452A (ja) * 1990-09-11 1992-04-22 Hidefumi Hirai 金属粒子及び／又は金属化合物粒子担持物、及びその製造方法

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001054216A3 (fr) * 2000-01-18 2002-02-21 Univ Ramot Pile a combustible a membrane conductrice de protons
US6447943B1 (en) 2000-01-18 2002-09-10 Ramot University Authority For Applied Research & Industrial Development Ltd. Fuel cell with proton conducting membrane with a pore size less than 30 nm
US6492047B1 (en) 2000-01-18 2002-12-10 Ramot University Authority For Applied Research & Industrial Development Ltd. Fuel cell with proton conducting membrane
US7413824B2 (en) 2000-01-18 2008-08-19 Tel Aviv University Future Technology Development L.P. Direct oxidation fuel cell with a divided fuel tank having a movable barrier pressurized by anode effluent gas
US8092955B2 (en) 2000-01-18 2012-01-10 Tel-Aviv Univrsity Future Technology Development L.P. Fuel cell having fuel tank directly attached to anode allowing pump-free fuel delivery
WO2003046265A3 (fr) * 2001-11-26 2003-11-13 Massachusetts Inst Technology Production de films epais d'alumine anodique poreuse et de reseaux de nanocables sur un substrat solide
US7267859B1 (en) 2001-11-26 2007-09-11 Massachusetts Institute Of Technology Thick porous anodic alumina films and nanowire arrays grown on a solid substrate
US7472576B1 (en) 2004-11-17 2009-01-06 State Of Oregon Acting By And Through The State Board Of Higher Education On Behalf Of Portland State University Nanometrology device standards for scanning probe microscopes and processes for their fabrication and use

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WO1999008785A3 (fr) 1999-05-27
DE19734973A1 (de) 1999-02-25

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