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
  • B01J15/00—Chemical processes in general for reacting gaseous media with non-particulate solids, e.g. sheet material; Apparatus specially adapted therefor
  • B01J15/005—Chemical processes in general for reacting gaseous media with non-particulate solids, e.g. sheet material; Apparatus specially adapted therefor in the presence of catalytically active bodies, e.g. porous plates
• • 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
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/0093—Microreactors, e.g. miniaturised or microfabricated reactors
• • 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
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/24—Stationary reactors without moving elements inside
  • B01J19/248—Reactors comprising multiple separated flow channels
  • B01J19/249—Plate-type reactors
• • 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
  • B01J23/002—Mixed oxides other than spinels, e.g. perovskite
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  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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  • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
  • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
  • B01J23/48—Silver or gold
  • B01J23/52—Gold
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  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J29/00—Catalysts comprising molecular sieves
  • B01J29/89—Silicates, aluminosilicates or borosilicates of titanium, zirconium or hafnium
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/64—Pore diameter
  • B01J35/651—50-500 nm
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/66—Pore distribution
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/02—Impregnation, coating or precipitation
  • B01J37/0215—Coating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/02—Impregnation, coating or precipitation
  • B01J37/0215—Coating
  • B01J37/0217—Pretreatment of the substrate before coating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/02—Impregnation, coating or precipitation
  • B01J37/0215—Coating
  • B01J37/0225—Coating of metal substrates
  • B01J37/0226—Oxidation of the substrate, e.g. anodisation
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
  • C07C51/21—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen
  • C07C51/255—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of compounds containing six-membered aromatic rings without ring-splitting
  • C07C51/265—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of compounds containing six-membered aromatic rings without ring-splitting having alkyl side chains which are oxidised to carboxyl groups
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
  • C07C51/31—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation of cyclic compounds with ring-splitting
  • C07C51/313—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation of cyclic compounds with ring-splitting with molecular oxygen
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00781—Aspects relating to microreactors
  • B01J2219/00783—Laminate assemblies, i.e. the reactor comprising a stack of plates
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00781—Aspects relating to microreactors
  • B01J2219/00819—Materials of construction
  • B01J2219/00835—Comprising catalytically active material
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00781—Aspects relating to microreactors
  • B01J2219/00873—Heat exchange
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/24—Stationary reactors without moving elements inside
  • B01J2219/2401—Reactors comprising multiple separate flow channels
  • B01J2219/245—Plate-type reactors
  • B01J2219/2451—Geometry of the reactor
  • B01J2219/2453—Plates arranged in parallel
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/24—Stationary reactors without moving elements inside
  • B01J2219/2401—Reactors comprising multiple separate flow channels
  • B01J2219/245—Plate-type reactors
  • B01J2219/2451—Geometry of the reactor
  • B01J2219/2456—Geometry of the plates
  • B01J2219/2458—Flat plates, i.e. plates which are not corrugated or otherwise structured, e.g. plates with cylindrical shape
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/24—Stationary reactors without moving elements inside
  • B01J2219/2401—Reactors comprising multiple separate flow channels
  • B01J2219/245—Plate-type reactors
  • B01J2219/2461—Heat exchange aspects
  • B01J2219/2462—Heat exchange aspects the reactants being in indirect heat exchange with a non reacting heat exchange medium
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/24—Stationary reactors without moving elements inside
  • B01J2219/2401—Reactors comprising multiple separate flow channels
  • B01J2219/245—Plate-type reactors
  • B01J2219/2476—Construction materials
  • B01J2219/2477—Construction materials of the catalysts
  • B01J2219/2479—Catalysts coated on the surface of plates or inserts
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/24—Stationary reactors without moving elements inside
  • B01J2219/2401—Reactors comprising multiple separate flow channels
  • B01J2219/245—Plate-type reactors
  • B01J2219/2491—Other constructional details
  • B01J2219/2497—Size aspects, i.e. concrete sizes are being mentioned in the classified document
• • 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
  • B01J2523/00—Constitutive chemical elements of heterogeneous catalysts
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
• • 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
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/249921—Web or sheet containing structurally defined element or component
  • Y10T428/249953—Composite having voids in a component [e.g., porous, cellular, etc.]

Definitions

• the present invention relates to a supported adhesion-resistant catalyst layer with high planarity and low tolerance of the layer thickness, a process for their preparation, their use in heterogeneously catalytic processes and a reactor containing such a catalyst layer.
• a metallic reaction tube with a catalytic coating containing a multimetal oxide composition which can be used in catalytic gas-phase reactions.
• the catalytic layer is applied directly to the metallic reaction tube in the form of a solution, emulsion or dispersion without adhesion-promoting intermediate layer. This can be done by spraying or dipping.
• Typical layer thicknesses range from 10 to 1000
• DE 199 59 973 A1 describes a process for the preparation of arrays of heterogeneous catalysts composed of a body having continuous channels in which different catalysts are applied.
• the method is intended to expand the known spectrum of arrays.
• the method is automatable.
• a porous diesel exhaust gas filter wherein a flow filter body is used with honeycomb wall structure, whose surface is coated with catalytically active material.
• a surface-enlarging coating is applied to the filter body by wash-coat coating, e.g. by applying a sol with small colloidal particles to the fired filter body.
• a catalytically active metal layer can be applied, for example by impregnating the filter body with a metal slurry.
• US Pat. No. 5,316,661 describes a process for the crystallization of a zeolite layer onto a substrate.
• WO-A-03 / 33,146 supported catalysts for the selective oxidation of carbon monoxide have a catalyst layer, which is applied to a metallic carrier via an adhesion-promoting layer of a crystalline silicate and silicon dioxide particles.
• the adhesion-promoting layer is through Application of an aqueous mixture of crystalline silicate and silcasol produced on the metallic support.
• EP-A-1 043,068 discloses a process for the preparation of a supported catalyst in which a catalyst-containing material is mixed with a solvent and deposited by spraying on a substrate heated above the boiling point of the solvent. The method enables a targeted deposition of the catalyst material with large active surfaces and good adhesion to a substrate.
• microreactors with catalytic wall elements and wall spacing ⁇ 1mm have been proposed. Examples of this are described in DE 100 42 746 A1 and DE 101 10 465 A1.
• a reaction mixture is passed between each two catalytically coated parallel plate-shaped wall elements.
• a reactor consists of a series of wall elements. Due to the small wall element spacing, a high wall to volume ratio is achieved, which allows a high heat removal rate and a mode of operation with under normal conditions explosive reaction mixtures. The high heat removal rate allows a very good temperature control while avoiding hot spots ("hot spots") in strongly exothermic reactions. Wall reactors can therefore be operated at a higher temperature level than in polytropic driving. As a result, in catalytic
• catalytic wall elements consisting of a plate with devices for fastening and sealing.
• the plate On the reaction side, the plate has one or more planar catalyst-coated surface elements.
• the back of the plate can be varied, often channels are suitable for a cooling or heating medium.
• the layers must be sufficiently resistant to adhesion, to prevent spalling during installation and operation
• the layer thickness must be as uniform as possible, so that the flow velocity in the reactor over the reactor width and reactor length is approximately constant, this criterion plays an outstanding role, especially in microreactors the layer thickness must be sufficiently high to introduce enough catalytically active material into the reactor; typical layer thicknesses are 20 ⁇ m to 3 mm
• the catalyst layer must have a sufficient catalytic activity, that is, a sufficiently high internal surface and porosity
• the mass transfer resistance in the catalyst layer must be sufficiently low.
• the object of the present invention is to provide a catalyst layer which satisfies these requirements.
• a further object of the present invention is to provide a method by which adhesive-resistant catalyst layers with high planarity and low tolerance of the layer thickness and with low mass transfer resistance can be produced in a simple and economical manner and which can be used universally with a multiplicity of catalyst systems ,
• An object of the invention is a support with catalytic coating comprising at least one porous catalyst layer having cavities.
• cavities are understood to mean irregular cavities with dimensions of greater than 5 ⁇ m in at least two dimensions or with cross-sectional areas of at least 10 ⁇ m 2 .
• cavities are substantially closed and connected essentially only by pores with diameters of less than 5 microns or cracks with a width of less than 5 microns with the layer surface or other cavities. Cavities can be detected in SEM microscopic sectional images of resin-impregnated catalyst layers. The determination of the cross-sectional area or the dimensions can be carried out by methods known per se, for example by quantitative microscopy.
• irregular voids are understood as meaning cavities with ashpary and / or acylindrical geometry which deviates greatly from the ideal spherical and / or cylindrical shape, the inner surface of which is local Roughness and macropores exists. In contrast to cracks, cavities have no clear preferred direction.
• Cavities are a component of the pore system. They are particularly large macropores. Macropores are pores with a diameter greater than 50 nm in the sense of the IUPAC definition.
• the proportion of cavities in the catalyst layer is preferably selected such that the visible area fraction of the cavities in a representative sectional image is between 2 to 60%, preferably between 3 to 50% and very particularly preferably between 5 and 35%, visible only in the sectional view Surfaces larger than 10 ⁇ m 2 are considered cavities.
• the contrast and the resolution in the image evaluation should be chosen so that only cavities - in the case of resin-poured layers recognizable by a particularly dark contrast - and no layer material and no outgoing from the cavities pores or cracks are detected with diameters smaller than 5 microns.
• the arithmetic mean of the area proportions of five randomly selected cross-sectional images distributed over the layer is to be used.
• the cavities prevent the propagation of cracks within the layer and thus help to reduce mechanically or thermally induced stresses, such as those that occur during installation of the catalytic converter or during operation.
• cracks occurring in the layer end up in cavities and "run dead” there (see Figure 1).
• For cavity-free layers, such cracks run through the entire layer and lead to mechanical instability
• the layers according to the invention show high adhesive tensile strengths even after mechanical or thermal stress. This advantageously results in a low sensitivity in the handling and use of the catalyst layer such as e.g. during installation and operation.
• these layer systems show adhesion tensile strengths of> 1 kPa (measured in accordance with DIN EN ISO 4624), in particular> 10 kPa and especially> 50 kPa.
• the catalyst layer according to the invention preferably has further macropores of smaller diameter in a high proportion.
• the catalyst layer contains a pore system in which at least 50%, preferably at least 70%, of the pore volume is formed by macropores having a diameter of at least 50 nm.
• Pore volume is understood to mean the volume detectable by means of mercury porosimetry according to DIN 66133 in pores having a diameter of greater than 4 nm. It assumes a contact angle of 140 ° and a surface tension of 480 mN / m for mercury. Before the measurement, the sample is dried at 105 ° C. The proportion of pore volume in macropores is also determined by mercury porosimetry.
• the high proportion of macropores according to the particularly preferred embodiment is the cause of the low mass transport resistance within the catalyst layer. This makes the use of thicker layers possible without sacrificing selectivity and activity. Thicker layers offer the advantage of providing more catalyst mass per area. The costs, in particular of a microreactor, increase with the area required, as a result of which thicker layers result in cost-saving potentials.
• the combined pore and cavity volume of a catalyst layer determinable by saturating water absorption and differential weighing is typically from 30 to 95%, preferably from 50 to 90%, based on the total volume of the layer.
• the carrier coated according to the invention has a uniform layer thickness with a tolerance of preferably less than ⁇ 30 ⁇ m.
• the carriers can have any geometry and consist of different materials.
• they can be pipes.
• flat bodies are used, in particular plates. It is particularly preferred to use sheet-like bodies which have surface depressions on which the catalyst layers are applied or which have grooves in addition to flat recesses.
• thermal sheets are so-called thermal sheets.
• This is generally understood to mean at least two sheets arranged at least partially in parallel, which are connected to one another in point-like contact regions, for example by welding or soldering, and are spaced outside of these contact regions.
• thermal sheets have a cushion-like structure, wherein a net-like channel pattern is formed between the surfaces of the sheets which are connected to one another via the contact regions and facing one another.
• this channel pattern can serve as a reaction space charged with a catalyst and, on the other hand, coolant can flow through it.
• Thermo sheets are described inter alia in DE-A-101 08 380 and DE-C-100 11 568 and are commercially available from DEG Intense Technologies & Service GmbH, Germany.
• the carrier substrate is preferably made of metallic or ceramic materials.
• the support may be made of a metal containing aluminum, iron, copper or nickel or a metal alloy; or it may be made of ceramics, such as aluminum, titanium or silicon oxide, zirconium oxide, silicon carbide or cordierite.
• the surface of the carrier substrate may be arbitrary. In addition to smooth, roughened or porous surfaces can be used.
• the surface may consist of the material of the carrier substrate or of a layer of additionally applied material, for example having an oxide layer.
• the thickness of the catalyst layer can cover wide ranges; it is typically 50 to 3000 .mu.m, preferably 200 to 1000 .mu.m, it being possible for the catalyst layer to be composed of individual layers which may have the same or different compositions.
• the catalyst layer comprises an adhesion-promoting layer applied directly to the surface of the support and which can have no catalytic effect.
• Typical thicknesses of this adhesion-promoting layer are less than 100 ⁇ m, preferably from 100 nm to 80 ⁇ m.
• adhesion-promoting layers exhibit a matrix which is substantially homogeneous in the micrometer range and preferably contain no individual structures of more than 5 ⁇ m in diameter, such as may arise, for example, when coarser particles are used in the suspension suspension.
• the adhesion-promoting layer has no cavities in contrast to the catalytic covering layer.
• At least one macroporous layer of catalytically active material having structures with a diameter of more than 1 ⁇ m is applied to this first layer.
• the material of the first adhesion-promoting layer can be arbitrary as long as it does not change under the reaction conditions in which the catalyst layer is used. These may be typical binder materials, such as inorganic oxides and / or temperature-resistant plastics.
• the first layer may also contain catalyst.
• Examples of materials that make up the first adhesion-promoting layer are silica, alumina, zirconia, titania, and mixtures thereof.
• the cavity-containing layer typically contains structures derived from particles greater than 1 ⁇ m in diameter from catalytically active material and optionally further inert material.
• the catalytic materials can be widely chosen. Of particular interest are catalyst systems for strongly exo- or endothermic reactions, especially for oxidation reactions. They are e.g. as basic systems to be varied with promoters:
• - Multimetal oxides which consist of a selection of the oxides of molybdenum, bismuth, vanadium, tungsten, phosphorus, antimony, iron, nickel, cobalt and copper as the main body in addition to other dopants - zeolites such as molecular sieves based on titanium-containing molecular sieves of the general formula (SiO 2 ) I - X (TiO 2 ) X , such as titanium silicalite-1 (TS-1) having MFI crystal structure, titanium silicalite-2 (TS-2) having MEL crystal structure, titanium beta zeolite having BEA crystal structure, and titanium silicalite-48 with the crystal structure of zeolite ZSM 48.
• - Fischer-Tropsch catalysts in particular based on Co or Fe
• the following catalyst systems are particularly preferably used:
• Titansilikalit-1 - metals of Group VIII B of the Periodic Table preferably the platinum metals, in particular Pd 1 combined with metals of Group IB of the Periodic Table, preferably with Au and an alkali metal salt preferably an organic acid, more preferably potassium acetate, and optionally further promoters in one oxide support matrix, preferably in an oxide with a high silica content
• Metals of group VIII B of the Periodic Table preferably of platinum metals, in particular Pd, combined with metals of group II B of the Periodic Table, preferably with Cd and an alkali metal salt, preferably an organic acid, more preferably potassium acetate, and optionally further promoters in an oxidic support matrix, preferably in a high oxide
• Ag on an alumina which is preferably at least partially in the alpha phase and optionally further admixtures such as alkali metals, such as Cs 1 and / or metals of group VII B of the Periodic Table, as Re
• the catalytically active materials may be in an inert or supporting matrix of inorganic oxides or thermostable plastics.
• Preferred materials of this matrix are oxides of Si, Al, Ti, Zr and / or mixtures thereof.
• the thickness of the catalytically active layer is particularly uniform, ie the layer is characterized by a high planarity and a low tolerance in the layer thickness. This is shown in measurements of the layer thickness according to the eddy current principle according to DIN EN ISO 2360 in a small standard deviation in a variety of individual measurements of ⁇ 35 microns, preferably ⁇ 25 microns.
• the local roughness is relatively high. This local roughness does not affect the critical residence time distribution across the gap width and improves the mass transport between the gas space and the catalyst layer, since it leads to at least partially turbulent flows in the gas space more quickly. In the microscope, a particularly open structure of the surface can be seen, which ensures a good penetration of the reactants.
• This open pore structure is inventively designed by open, ie incomplete preforms of cavities having dimensions of greater than 5 microns in at least two dimensions, which are located on the surface of the layer.
• the wearer facing inner surfaces of these open structures have pores, which go into the interior of the catalytically active layer, and thus ensure the mass transfer into the catalytic layer.
• Individual connections between the open structures on the surface and the closed cavities located in the interior of the catalytic layer can also be present via macroporous channels and / or individual connections can be present between closed cavities within the catalytically active layer.
• the local roughness is reflected in the profilogram, which can be recorded by a probe, by a high number of maxima, minima and zero crossings per unit length and a high roughness.
• the layers are characterized by particularly sharp and narrow peaks.
• the average number of zero crossings is typically> 2 per mm, preferably> 2.5 per mm, more preferably 3-8 per mm, if sufficiently long measuring sections are used (measured with Form Talysurf Series 2 from Taylor-Hobson Precision).
• a zero crossing is defined by the intersection of the profile with the centerline.
• the roughness R z measured by means of probe and determined according to DIN EN ISO 4287 is> 70 microns, preferably> 100 microns, more preferably> 120 microns. This is based on a total measuring distance of 40 mm and a single measuring distance of 8 mm.
• Non-inventive catalyst coatings such as are obtainable, for example, by conventional casting or doctoring processes generally have greater variations in the layer thickness, but generally do not show the favorable locally rough structure. Coating methods which generally allow precise adjustment of the layer thickness, such as e.g. CVD, are very expensive and have locally smooth structures.
• the roughness of the surface may optionally be reduced by a post-treatment such as grinding and polishing.
• the catalytic coating support of the invention can be prepared by a particularly simple and economical process. This is also the subject of the present invention.
• the method comprises the measures: a) presentation of a carrier substrate, b) if appropriate, application of a primer layer c) spraying a suspension with at least 30 wt.% solids content containing particles of catalytically active material having a mean diameter (D 50 value) of at least 5 microns (determined by laser diffraction in suspension) and / or its precursor and optionally other components catalytically active Layers, and d) optionally one or more repetitions of step c).
• D 50 value mean diameter
• the method is carried out so that a flow of the sprayed suspension on the carrier substrate is largely prevented. That is, the moisture content of the drops at the time of impact is chosen so that on the one hand a sufficiently high viscosity prevents the free deliquescence but on the other hand, the droplets have a sufficiently high aggregation capacity to connect firmly with the underlying layer.
• This can be checked in the light microscope: Deflated layers have a smooth structure, whereas the method according to the invention produces a structure which is rough on a micrometer scale and has openings and valleys.
• the expert can choose from the parameters solids content, mass flow, spray distance, droplet size, substrate and suspension temperature, a window that allows such a splash result.
• a nozzle technique is used in the spraying, which allows a good focusing of the spray jet, so that the overspray, i. the loss of material by next to the carrier or on not to be coated parts of the carrier impacted spray material is minimized.
• the overspray i. the loss of material by next to the carrier or on not to be coated parts of the carrier impacted spray material is minimized.
• the spray cone can be concentrated by additional compressed air nozzles.
• the carrier substrate during the coating at elevated temperature is below the boiling temperature of the suspending agent.
• Preferred temperature for aqueous suspensions is 30-80 ° C.
• the particles of the suspension have a broad particle size distribution with a span > 1, 5.
• D x denotes the particle diameter of the largest particle in the volume fraction of the smallest particles with a volume fraction of x% of the total particle volume.
• the particles of the suspension have a rough surface and an irregular shape, as arises, for example, by grinding or breaking.
• a binder is added to the suspension.
• Suitable binders are inorganic or organic materials and mixtures thereof.
• inorganic binder materials in particular sols, very finely divided suspensions or solutions of the oxides of Al, Si, Ti, Zr or mixtures thereof can be used.
• Further preferred inorganic binders are very finely divided oxides having an average particle size (D 50 value) ⁇ 2 ⁇ m, such as pyrogenic oxides or very finely ground precipitated oxides, mechanical crosslinkers such as glass fibers or special needle-shaped or rod-shaped crystallites, such as Actigel TM 208 (Manufacturer ITC-Floridin).
• organic binder materials in particular, polyalcohols such as e.g. Glycerol, ethylene glycol or polyvinyl alcohol, PTFE, polyvinyl acetate, cellulose derivatives such as methyl cellulose or cellulose fibers are used.
• polyalcohols such as e.g. Glycerol, ethylene glycol or polyvinyl alcohol, PTFE, polyvinyl acetate, cellulose derivatives such as methyl cellulose or cellulose fibers are used.
• a preferred variant of the method according to the invention comprises the optional sub-step b), the spraying of a first suspension containing nanoparticulate material without particles with diameters of more than 5 microns on the surface of the support in an amount such that a first adhesion-promoting layer with a thickness of up to to 80 microns, preferably 5-30 microns formed.
• the inventive method comprises the above-defined step a), the optional step b) and c ' ) the spraying of a Suspension with at least 30 wt.% Solids containing particles of inert and / or catalytic materials having an average diameter (Dso value) of at least 5 microns (determined by laser diffraction in suspension) and optionally further constituents of catalytically active layers, and d '), if appropriate, one or more repetitions of step c ' ) and as step e) after the preparation of such a layer system, its impregnation with catalytically active materials and / or their precursors and / or promoters acting materials and / or their
• these may optionally be dried and / or calcined before further treatment of the layers takes place.
• organic or other decomposable residues can be removed.
• the pretreatment may consist of a sequentially variable combination of these individual methods.
• the carrier substrate used in the method according to the invention may optionally be pretreated before the coating, in particular by roughening the carrier substrate surface, which is to be coated with catalyst, by mechanical, chemical and / or physical methods.
• This pretreatment can lead to a further improved adhesion of the layers to be applied on the support. This is particularly recommended for metallic carriers.
• the carrier substrate surface to be coated by mechanical methods such as
• Sandblasting or sanding are roughened or by chemical methods, such as etching with acids or bases. Fat residues can be removed by solvents.
• the réellespritzende catalyst suspension contains at least one or more catalytically active materials or their precursors.
• Precursors may be, for example, nitrates, oxalates, carbonates, acetates or other salts which can be converted into oxides by thermal or oxidative decomposition, for example.
• the catalytically active materials or their precursors can be present in molecular, colloidal, crystalline or / and amorphous form.
• the actual catalytic materials, or their precursors, may be contained in the suspension or later applied by impregnation.
• acids or bases can be added.
• organic constituents such as surfactants, binders or pore formers may be included.
• As a suspension or solvent is particularly suitable water. But it can also be used organic liquids.
• This suspension to be applied is applied by spraying or spraying.
• Non-wetting parts can be covered or taped.
• the beam can be done manually or preferably automated. In the automated procedure, it is advisable to move the nozzle computer-controlled on the surface to be sprayed and thereby monitor the order of the material and other process parameters targeted and set.
• the spraying of the individual layers can take place in a manner known per se, the skilled person being able to use a large number of process parameters. Examples include the injection pressure, the spray distance, the spray angle, the feed rate of the spray nozzle or fixed nozzle of the substrate, the nozzle diameter, the material flow rate and the geometry of the spray jet. Furthermore, the properties of the suspensions to be sprayed exert an influence on the quality of the resulting layers, for example density, dynamic viscosity, surface tension and zeta potential of the suspension used.
• a layered application is carried out. It may be advantageous further to heat the carrier material at least during the spraying of the first suspension, but advantageously during the application of all layers. In this case, the support is preferably heated to a temperature below the boiling temperature of the solvent used.
• one or two thermal treatments for drying and calcination may follow. If the applied layer is not already dried, a separate drying, for example, at
• the drying and the calcination can be carried out in an oxidizing atmosphere, for example in air, or in an inert atmosphere, for example in nitrogen.
• the carrier layer is coated with the solution or suspension containing the components or immersed in them or sprayed. After impregnation, drying and / or calcination may be initiated.
• coated according to the invention supports can be used in a variety of reactors, for example in plate or tubular reactors.
• a further subject of the invention is a reactor containing at least one of the carriers according to the invention with catalytic coating.
• microreactors are to be understood as meaning those reactors in which at least one of the dimensions transversal to the flow direction of the reaction space or the reaction spaces is less than 10 mm, preferably less than 1 mm, particularly preferably less than 0.5 mm.
• Wall reactors and in particular microreactors have a plurality of reaction spaces, preferably a plurality of reaction spaces running parallel to one another.
• the dimensioning of the reaction spaces can be arbitrary, provided at least one dimension moves in the range of less than 10 mm.
• the reaction spaces may have round, ellipsoidal, triangular or polygonal, in particular rectangular or square cross sections.
• the or a dimension of the cross section is smaller than 10 mm, that is at least one side length or the or a diameter.
• the cross section is rectangular or round and only one dimension of the cross section, ie one side length or the diameter moves in the range of less than 10 mm.
• the material enclosing the reaction space may be arbitrary provided that it is stable under the reaction conditions, sufficient heat removal is permitted and the surface of the reaction space is completely or partially coated with the layer system according to the invention containing catalytically active material.
• the present invention thus also relates to a reactor which can be used in particular for the heterogeneously catalyzed gas phase reaction, comprising: i) at least one reaction space, of which at least one dimension is smaller than 10 mm, and ii) the surface of the reaction space is as defined above
• a preferred microreactor is characterized in that it comprises a plurality of vertically or horizontally and parallelly arranged spaces, each having at least one inlet and one outlet, the spaces being formed by stacked plates or layers, and a part of the spaces being reaction spaces of which at least one dimension is in the range of less than 10 mm, and the other part of the spaces are heat transport spaces, the supply lines to the reaction spaces being connected to at least two distribution units and the outlets from the reaction spaces being connected to at least one collection unit; Heat transfer between reaction and heat transport spaces is carried by at least one common room wall, which is formed by a common plate.
• a microreactor of this type which is used with particular preference, has spacer elements arranged in all chambers and contains on the inner walls of the reaction chambers At least partially applied by the inventive method catalyst material, has a hydraulic diameter, which is defined as the quotient of four times the surface to the circumferential length of the free flow cross-section, in the reaction chambers less than 4000 .mu.m, preferably less than 1500 .mu.m, and more preferably less than 500 microns, and a ratio between the perpendicular smallest distance between two adjacent spacer elements to the slot height of the reaction space after a coating with catalyst of less than 800 and greater than or equal to 10, preferably less than 450 and more preferably less than 100.
• Yet another object of the invention is the use of the described carriers in a reactor for reacting organic compounds. These may be reactions in the gas phase, in the liquid phase or in the phase with supercritical state.
• the reactor is preferably a wall reactor, particularly preferably a microreactor.
• the reaction of organic compounds is preferably a strongly exo- or endothermic reaction (amount of ⁇ H greater than 50 kJ / mol).
• reaction examples include oxidation or ammoxidation reactions, for example:
• Epoxidation of olefins such as the oxidation of propene to propene oxide or of ethylene to ethylene oxide or allyl chloride to ephichlorohydrin
• reactions are hydrogenation reactions on organic compounds, for example the hydrogenation of aromatics, nitro compounds and the selective hydrogenation of unsaturated organic compounds.
• Further reactions of interest are reactions of synthesis gas, e.g. Fischer-Tropsch reaction and methanol synthesis or condensation reactions, such as the reaction of acetone to isophorone.
• synthesis gas e.g. Fischer-Tropsch reaction and methanol synthesis or condensation reactions, such as the reaction of acetone to isophorone.
• Example 1 Wall catalyst TS-1 on aluminum 99.5
• a suspension of 16 g TS-1 with the particle size distribution D 10 / D 50 / D 90 8.05 / 41, 5 / 78.4, 20 g of a silica sol, 1, 8 g of waterglass and 2.8 g made of deionized water.
• the resulting suspension was dispersed for 2 minutes with a disperser at 15,000 rpm.
• a particle size distribution of the suspension of Dio / Dso / Dgo: 6.6 / 43.1 / 77.4 was measured.
• the preheated aluminum plates were coated with this suspension at a pressure of 0.7 bar by spraying in several steps with a spray distance of 20 cm.
• the catalyst system prepared in this way was tested for adhesive tensile strength and topography.
• An orthogonal adhesive tensile strength of 100 kPa was measured.
• For the roughness an arithmetic mean roughness of 29 ⁇ m was measured, the tolerance of the total layer thickness was ⁇ 16 ⁇ m.
• Figure 3 is a microscopic sectional view of the catalyst layer system made according to this example.
• the proportion of cavities of the catalyst system produced in this way is 32% of the layer area considered in the sectional view.
• the pore distribution measured by mercury porosimetry shows that 95% of the pores have a diameter> 50 nm and the total porosity with the cavities is 49%.
• This catalyst system was a suspension of 37.5 g of ground catalyst consisting of palladium, gold and silica, with a particle size distribution D 1o / D 5 o / D 9 o: 3.3 / 22.1 / 87.2 microns with 31st , 25 g of a silica sol and 31.25 g of water and then dispersed for 2 minutes with a disperser at 15000 U / min.
• the particle size distribution of the suspension after dispersion is D ⁇ D 50 ID 90 : 3.8 / 17.2 / 67.0.
• the preheated steel plates were coated with this suspension at a pressure of 0.8 bar by spraying in several steps with a spraying distance plate surface to spray nozzle of 20 cm.
• a spraying distance plate surface to spray nozzle of 20 cm. was used a two-fluid nozzle with a nozzle diameter of 1, 8 mm.
• a 20 ⁇ m thick layer was applied, in the subsequent steps each 40 ⁇ m thick layers.
• the catalyst layer system produced in this way had a total thickness of 786 ⁇ m.
• the plates were 4 min at 4O 0 C dried.
• the plates were calcined at 25O 0 C for 6 h.
• FIG. 5 shows a profilogram according to DIN ISO 4287 of the surface of the layer system produced according to this example (measured with the form Talysurf Series 2, Taylor Hobson Precision).
• the abscissa indicates the scan width in mm, while the ordinate represents the relative tread depth in ⁇ m.
• the pore distribution measured by mercury porosimetry shows that 84% of the pores have a diameter of> 50 nm.
• the total porosity with cavities is 68%.
• the two other plates were installed in a pilot reactor such that their grooves formed a 0.53 mm high and 30 mm wide channel.
• a reaction gas consisting of ethylene, oxygen and acetic acid was passed to determine the catalytic property of the catalyst system. This experiment was carried out at a temperature of 155 ° C and a pressure of 9 bar over a period of 180 h.
• Example 3 Mixed oxide catalyst on stainless steel
• a suspension was prepared from 37.5 g acrolein catalyst according to EP0900774 Example 1 (preparation of catalyst 2), 31, 25 g of a silica sol and 31, 25 g of deionized water and then for 2 min with a dispersing device (Ultra Turrax . dispersed) at 15,000 rpm "1 the particle size distribution after dispersing Dio / D 5 o / D o 9 was:.
• a dispersing device Ultra Turrax . dispersed
• the preheated steel plates were coated with the thus produced suspension at a pressure of 1 , 6 bar by spraying in several steps with a distance Spray nozzle to the plate surface of 20 cm coated using a two-fluid nozzle with a nozzle diameter of 0.8 mm.
• the first step a layer of 20 microns was applied, in the subsequent steps by increasing the flow of material At the nozzle, layer thicknesses of 40 ⁇ m each were dried in.
• the plates were dried at 50 ° C. for 4 minutes, after the last step they were calcined at 450 ° C. for 8 hours ,
• the catalyst layers were examined for adhesive tensile strength, topography and porosity.

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