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
  • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
  • B01J21/16—Clays or other mineral silicates
• • 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
  • B01J35/51—Spheres
• • 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
  • B01J35/615—100-500 m2/g
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/63—Pore volume
  • B01J35/633—Pore volume less than 0.5 ml/g
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/64—Pore diameter
  • B01J35/647—2-50 nm
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • 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
  • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
  • B01J37/0018—Addition of a binding agent or of material, later completely removed among others as result of heat treatment, leaching or washing,(e.g. forming of pores; protective layer, desintegrating by heat)
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
  • C04B35/16—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silicates other than clay
  • C04B35/18—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silicates other than clay rich in aluminium oxide
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
  • C04B38/0006—Honeycomb structures
  • C04B38/0016—Honeycomb structures assembled from subunits
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
  • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
  • C04B2111/00793—Uses not provided for elsewhere in C04B2111/00 as filters or diaphragms
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
  • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
  • C04B2111/0081—Uses not provided for elsewhere in C04B2111/00 as catalysts or catalyst carriers

Definitions

• the present invention relates to an open-pore catalyst support, a process for its preparation and its use.
• Vinyl acetate monomer is an important monomer building block in the synthesis of plastic polymers.
• the main areas of application of VAM are i.a. the preparation of polyvinyl acetate, polyvinyl alcohol and polyvinyl acetal and the co- and terpolymerization with other monomers such as ethylene, vinyl chloride, acrylate, maleate, fumarate and vinyl laurate.
• VAM is predominantly produced in the gas phase from acetic acid and ethylene by reaction with oxygen, wherein the catalysts used for this synthesis preferably contain Pd as active metal, Au as a promoter and an alkali metal component as a co-promoter, preferably potassium in the form of the acetate.
• the metals Pd and Au are not present in the form of metal particles of the respective pure metal, but rather in the form of Pd / Au alloy particles of possibly different composition, although the presence of unalloyed particles are not excluded can.
• Cd or Ba can also be used as co-promoter.
• VAM is predominantly using so-called
• Catalyst support molded bodies are contained (cf., for this purpose, EP 565 952 A1, EP 634 214 A1, EP 634 209 A1 and EP 634 208 A1), while the regions of the catalyst support situated further in the interior are free of noble metal. With the help of coated catalysts is in many cases a more selective
• the shell catalysts known in the prior art for the preparation of VAM can be, for example, catalyst supports based on silica, alumina, aluminosilicate, titanium oxide or zirconium oxide (cf., for this purpose, EP 839 793 A1, WO 1998/018553 A1, WO 2000/058008 A1 and WO 2005/061107 Al).
• catalyst supports based on titanium oxide or zirconium oxide are currently scarcely used since these catalyst supports are not long-term stable with respect to acetic acid or are relatively expensive.
• the majority of the currently used catalysts for the preparation of VAM are coated catalysts with a Pd / Au shell on a porous amorphous formed as a ball aluminosilicate on the basis of natural phyllosilicates, which are impregnated with potassium acetate as a co-promoter.
• VAM shell catalysts are usually prepared in a so-called chemical way in which the catalyst support with solutions of corresponding metal precursor compounds, for example by immersing the carrier in the solutions or by Incipient-Wetness method (pore filling method), in which the carrier with a solution volume corresponding to its pore volume is charged, impregnated.
• Incipient-Wetness method pore filling method
• the Pd / Au shell of the catalyst is produced, for example, by first impregnating the catalyst support in a first step with a Na 2 PdCl 4 solution and then in a second step the Pd component with NaOH solution on the catalyst support in the form of a Pd Hydroxide compound is fixed. In a subsequent separate third step, the catalyst support is then impregnated with a NaAuCl 4 solution and then the Au component is likewise fixed by means of NaOH. After fixing the noble metal components in the outer shell of the catalyst support, the support is then washed largely free of chloride and Na ions, then dried, calcined and finally reduced at 150 ° C. with ethylene.
• the Pd / Au shell thus produced usually has a thickness of about 100 ⁇ m to 500 ⁇ m.
• the catalyst support loaded with the noble metals is loaded with potassium acetate after the last fixation step or after the reduction step, with the loading of potassium acetate not only taking place in the outer shell loaded with precious metals, but rather completely impregnated with the co-promoter.
• a catalyst support is predominantly a spherical support with the name "KA-160" of
• VAM selectivities are about 90 mol .-% based on the supplied ethylene, wherein the remaining 10 Mol .-% of the reaction products are essentially CO 2 , which is formed by total oxidation of the organic starting materials / products.
• a further increase in the VAM selectivity or suppression of total oxidation is therefore desirable in order to minimize losses of starting material, to reduce so-called "hot spots" in the reaction tube and thus prolong the life of the VAM catalyst, and to add the CO 2 -purge in the recycle gas relieve.
• Catalysts can be produced which are characterized by a relatively high VAM selectivity.
• an open-pore catalyst support consisting of a material which comprises a natural phyllosilicate, wherein the catalyst support has an acidity of 10 .mu.l / g to 60 .mu.val / g, an average pore diameter of 10.5 nm to 14 nm specific surface area of 160 m 2 / g to 175 m 2 / g, a bulk density (agglomerate density) of 480 to 550 g / l, an Al 2 O 3 content of less than 2.5 wt .-% and a water absorbency greater than 65 % having .
• VAM catalysts can be produced by means of an open-pore catalyst support having the abovementioned values for acidity, average pore diameter, specific surface area, bulk density, Al 2 O 3 content and water absorbency according to the invention, characterized by higher selectivity and greater suppression of total oxidation compared to VAM Catalysts which have been prepared using a conventional open-cell catalyst support which does not have the above-mentioned values in said combination.
• the catalyst support according to the invention contains a natural phyllosilicate.
• natural phyllosilicate for which the term “phyllosilicate” is also used in the literature, is understood in the context of the present invention to originate from natural sources, untreated or treated silicate mineral, in which SiO 4 tetrahedron, which is the structural Form a basic unit of all silicates which are crosslinked in layers of the general formula [Si 2 O 5 ] 2. " These tetrahedral layers alternate with so-called octahedral layers in which a cation, especially Al and Mg, is octahedrally surrounded by OH or O.
• Phyllosilicates which are preferred in the context of the present invention are clay minerals, in particular kaolinite, beidellite, hectorite, saponite, nontronite, mica, vermiculite and smectites, with smectites and in particular montmorillonite being particularly preferred of the term "sheet silicates”
• sheet silicates For example, in “textbook of inorganic chemistry", Hollemann Wiberg, de Gruyter, 102nd edition, 2007 (ISBN 978-3-11-017770-1) or in "Römpp Lexicon Chemistry", 10th edition, Georg Thieme Verlag under the Term "phyllosilicate”.
• Typical treatments to which a natural layered silicate is subjected prior to use as a carrier material include, in particular, treatment with acids, in particular mineral acids such as, for example, hydrochloric acid, and / or calcining.
• the catalyst support according to the invention has an acidity of 10 .mu.l / g to 60 .mu.l / g.
• the degree of acidity of the catalyst support of the present invention may favorably influence the activity of a corresponding catalyst with respect to the gas-phase synthesis of VAM from acetic acid and ethene.
• the catalyst support has an acidity of from 20 .mu.l / g to 60 .mu.l / g.
• the acidity of the carrier can be increased, for example, by impregnating the carrier with acid.
• the acidity of a catalyst support is determined as follows: 1 g of the finely ground catalyst support is mixed with 100 ml of water (with a pH blank) and extracted with stirring for 15 minutes. It is then titrated with 0.01 N NaOH solution at least until pH 7.0, wherein the titration is carried out stepwise; Namely, 1 ml of the NaOH solution is added dropwise to the extract (1 drop / second), then waited 2 minutes, read the pH, 1 ml of NaOH is added dropwise, etc. The blank value of the water used is determined and the acidity Calculation corrected accordingly. The titration curve (ml 0.01 NaOH versus pH) is then plotted and the point of intersection of the titration curve at pH 7 is determined. Calculated are the molar equivalents in 10 ' ⁇ equiv / g carrier resulting from the NaOH consumption for the point of intersection at pH 7:
• the catalyst support according to the invention also has an average pore diameter of 10.5 nm to 14 nm. To the pore diffusion limitation of the invention To keep catalyst carrier largely low, it is provided according to a further preferred embodiments of the catalyst support according to the invention that the average pore diameter is 10.5 nm to 12 nm.
• the mean pore diameter is determined according to DIN 66134 (determination of the pore size distribution and the specific surface of mesoporous solids by nitrogen sorption from the N 2 absorption isotherm (method according to Barrett, Joyner and Halenda (BJH)).
• the catalyst support according to the invention also has a specific surface area of from 160 m 2 / g to 175 m 2 / g, preferably from 165 m 2 / g to 170 m 2 / g. It has been found that the VAM selectivity and the suppression of the total oxidation of a prepared by the catalyst support according to the invention VAM catalyst with almost constant activity of the catalyst are higher than in a conventionally prepared VAM catalyst, when the specific surface of the catalyst support according to the invention in the above mentioned areas.
• the specific surface area of the support according to the invention is determined according to DIN 66131 (determination of the specific surface area of solids by gas adsorption according to Brunauer, Emmett and Teller (BET)) and DIN 66132 by means of nitrogen.
• the catalyst support according to the invention also has a bulk density (bulk density) of 480 g / l to 550 g / l, preferably from 480 g / l to 520 g / l.
• the natural sheet silicate contains less than 2.5% by weight of Al 2 O 3 , preferably 0.1% by weight to 2.0% by weight and preferably 0.3% by weight to 1, 8 wt .-% Al 2 O 3 , based on the weight of im catalyst support according to the invention contained natural phyllosilicate.
• the Al 2 O 3 content in the natural layered silicate is set according to the invention to a relatively low value, as in the gas phase synthesis of VAM from acetic acid and ethene, a relatively low Al 2 O 3 content in the natural sheet silicate hardly adversely affects while at high Al 2 O 3 contents must be expected with a significant decrease in the pressure hardness of the catalyst support.
• Catalyst support is greater than 65%, preferably 66% to 80%, more preferably 67% to 75%, calculated as weight increase by water absorption.
• the absorbency is determined by soaking 10 g of the carrier sample with deionized water for 30 minutes until no sample is obtained from the carrier sample
• a particularly preferred natural layered silicate in the context of the present invention is montmorillonite, which is preferably used in the form of a bentonite.
• Bentonites are mixtures of various clay minerals containing predominantly montmorillonite (about 50% to 90% by weight).
• Other accompanying minerals can i.a. Quartz, mica and feldspar.
• the natural phyllosilicate is an acid-activated natural phyllosilicate.
• Acid-activated phyllosilicates are known in the prior art (see Rötnpp Lexikon Chemie, 10th Edition, Georg Thieme Verlag, term "bentonites") .
• the natural phyllosilicate in the support is preferably in the form of an acid-activated
• the acid-activated phyllosilicate is acid-activated montmorillonite which, according to the invention, is more preferably present in the form of an acid-activated bentonite in the carrier according to the invention.
• the catalyst support has a hardness greater than 60 N, preferably a hardness of 62 N to 80 N and more preferably a hardness of 65 N to 75 N.
• the determination of the hardness is carried out on spherical samples (diameter: 5 mm) using the tablet hardness tester 8M from Dr. Ing. Schleuniger Pharmatron AG (Switzerland). Before the measurement, the samples are dried over a period of 2 h at a temperature of 130 0 C. Hardness is calculated as the average of 99 measurements. For the measurements, the following selectable parameters of the 8M Tablet Hardness Tester are set as follows:
• the proportion of the catalyst support of natural layered silicate according to the invention is at least 50% by weight, preferably 55% by weight to 100% by weight, preferably 60% by weight to 99% by weight preferably from 65% to 98% by weight, and more preferably from 70% to 91% by weight, based on the weight of the catalyst support.
• the catalyst support has an integral pore volume of 0.25 ml / g to 0.8 ml / g.
• the VAM selectivity of a VAM catalyst prepared by means of the catalyst support according to the invention is dependent on the integral pore volume of the catalyst support. It is preferred that the catalyst support has an integral pore volume of 0.25 ml / g to 0.8 ml / g, preferably one of 0.4 ml / g to 0.75 ml / g, and preferably one of 0.5 ml / g to 0.7 ml / g.
• the integral pore volume is determined according to DIN 66134 (determination of the pore size distribution and the specific surface area of mesoporous solids by nitrogen sorption (method according to Barrett, Joyner and Halenda (BJH)).
• the integral pore volume of the catalyst support is formed by mesopores and macropores, preferably at least 90% and preferably at least 95%. This results in a reduced activity of a VAM catalyst produced by means of the catalyst support according to the invention, which is caused by diffusion limitation. in particular a Pd / Au coated catalyst with relatively large shell thickness, counteracted.
• micropores are understood to have a diameter of less than 2 nm, a diameter of 2 nm to 50 nm and a diameter greater than 50 nm the mesopores and macropores at the integral pore volume is determined on the basis of the pore volume distribution of the catalyst support according to the invention, which according to DIN 66134 (determination of the pore size distribution and the specific surface of mesoporous solids by
• Nitrogen sorption (method according to Barrett, Joyner and Halenda (BJH)) is determined.
• the natural phyllosilicate contained in the catalyst support has an SiO 2 content of at least 65 wt .-%, preferably one of at least 80 wt .-% and particularly preferably one of 90 wt % to 98% by weight. This ensures a high chemical resistance of the catalyst support according to the invention in the VAM synthesis.
• the catalyst support is formed as a shaped body.
• the catalyst support according to the invention is formed as a shaped body.
• the catalyst support may have any form which is known to those skilled in the art for the purpose of the invention.
• the catalyst support according to the invention as a sphere, cylinder, perforated cylinder, trilobus, ring, star, torus or strand, preferably as a rib strand or star strand, be formed.
• the catalyst support has a maximum dimension of 1 mm to 25 mm, preferably a maximum dimension of 3 mm to 15 mm.
• the catalyst support is formed as a ball.
• the ball has a diameter of 2 mm to 10 mm, preferably a diameter of 4 mm to 8 mm.
• the catalyst support is doped with at least one oxide of a metal selected from the group consisting of Hf, Ti, Nb, Ta, W, Mg, Re, Y and Fe.
• the doping can increase the activity of a VAM catalyst produced by means of the catalyst support according to the invention.
• the proportion of the catalyst support to doping oxide is between 1 wt .-% and 25 wt .-%, preferably 3 wt .-% to 15 wt .-% and preferably 5 wt. -% to 10 wt .-% based on the weight of the catalyst support.
• the doping can be done, for example, by surface doping, as they are from the State of the art is known, done or that
• Metal oxide / metal oxides may be incorporated in the matrix of the catalyst support.
• the catalyst support is free of ZrO 2 .
• Free of ZrO 2 means here that the proportion of the carrier to ZrO 2 is less than 200 ppm.
• the present invention further relates to a process, in particular for the preparation of a catalyst support according to the invention, comprising
• a first open-celled catalyst support consisting of a material comprising a natural layered silicate, wherein the first catalyst support has a mean pore diameter smaller than 10.5 nm, a specific surface area greater than 175 m 2 / g, a bulk density greater than 550 g / l , an Al 2 O 3 content greater than 2.5 wt .-% and - has a water absorbency less than 65%;
• VAM catalysts can be prepared which are characterized by a higher selectivity compared to VAM catalysts prepared using a conventionally prepared open-cell catalyst support, such as that described in US Pat
• the first catalyst support used in the process according to the invention has been obtained.
• Mineral acids are hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid, with hydrochloric acid, in particular 20% hydrochloric acid, being very particularly preferred.
• the first open-pored catalyst support can be any conventional open-pore catalyst support which comprises a natural phyllosilicate and which satisfies the values for average pore diameter, specific surface area, bulk density, Al 2 O 3 content and water absorbency given above.
• the treatment of the first catalyst support with mineral acid is carried out until a second catalyst support is obtained which has an acidity of 10 .mu.l to 60 .mu.val, an average pore diameter of 10.5 nm to 14 nm , a specific surface area of 160 m 2 / g to 175 m 2 / g, a
• the treatment with mineral acid over a period of 5 h to 100 h more preferably carried out over a period of 7 h to 50 h and in particular over a period of 8 h to 15 h becomes.
• the treatment with mineral acid at elevated temperature in particular at above 50 0 C is performed.
• the second catalyst support is washed after treatment with mineral acid.
• the washing serves to liberate the obtained second open-pore catalyst support after treatment with mineral acid from acid residues as well as from the mineral phyllosilicate from the natural phyllosilicate optionally further dissolved components, wherein the washing is preferably carried out with water.
• the second catalyst support is calcined after washing.
• the calcination is preferably carried out at a temperature of 400 0 C to 800 0 C, more preferably at a temperature of 500 0 C to 700 0 C.
• the calcination is carried out over a period of 3 hours to 24 hours, preferably from 5 hours to 20 hours, in particular from 7 hours to 10 hours.
• the natural sheet silicate is montmorillonite, wherein it is particularly preferred that the montmorillonite is present as part of a bentonite.
• the natural layered silicate is an acid-activated natural layered silicate.
• the second catalyst support has a specific surface area of 165 m 2 / g to 170 m 2 / g.
• the second catalyst support has a hardness of greater than 60 N.
• the first catalyst support has an acidity of 1 .mu.l / g to 80 .mu.l / g.
• the Proportion of the first catalyst support of natural sheet silicate at least 50 wt .-% is.
• the first catalyst support has an integral pore volume of 0.25 ml / g to 0.8 ml / g.
• the second catalyst support has a bulk density of 480 to 520 g / liter.
• Sheet silicate has a SiO 2 content of at least 65 wt .-%.
• the first catalyst support is formed as a shaped body, wherein the first catalyst support preferably has a maximum dimension of 1 mm to 25 mm.
• the first catalyst carrier is a ball, wherein the ball in particular has a diameter of 2 mm to 10 mm.
• the first catalyst support is doped with at least one oxide of a metal selected from the group consisting of Hf, Ti, Nb, Ta, W, Mg, Re, Y and Fe, wherein the Proportion of the first
• Catalyst support of doping oxide is preferably 1 wt .-% to 25 wt .-%.
• the first catalyst support is free of ZrO 2 .
• the present invention further relates to a catalyst support according to the invention, obtainable by the process according to the invention.
• the present invention further relates to the use of the catalyst support according to the invention and of the catalyst support obtainable by the process according to the invention in the preparation of a catalyst for the synthesis of vinyl acetate monomer.
• the catalyst is a shell catalyst in whose shell Pd and Au of the oxidation state 0 are contained.
• a catalyst support according to the invention 700 g of a commercially available spherical KA support of the company Süd-Chemie with a diameter of about 5 mm, which had the parameters shown in Table 1, were transferred to a round bottom flask and at a temperature of about 50 0 C for a total of 30 hours 25% hydrochloric acid treated. The resulting treated support was washed with water and then dried. The dried support was calcined for 5 hours in the temperature range between 450 0 C and 670 0 C, whereby a catalyst support according to the invention was obtained, which had the parameters given in Table 1.
• Example 1 these were rotated for 65 min at room temperature in a round bottomed flask so that they reach a dry state.
• 81.93 g of a 0.38 M base mixture consisting of a 50:50 mixture of NaOH: KOH (ie 40.965 g of 0.38 molar NaOH + 40.965 g of 0.38 molar KOH) were added to the carrier beads and overnight Room temperature allowed to stand for 16.5 h.
• the catalyst precursor was reduced with 73.14 g of a 10% NaH 2 PO 2 solution for 2 hours.
• the carrier beads were washed with deionized water for 19 hours at room temperature with constant replacement of the water to remove Cl residues.
• the final value of the conductivity of the wash water was 4.6 ⁇ S.
• the catalyst was dried in a fluidized bed dryer at 90 0 C for 1 h.
• the dried catalyst was uniformly impregnated with a mixture of 25.25 g of a 2 molar KOAc solution and 19.18 g of H 2 O and left for 1 h at room temperature. Finally, it was re-dried in a fluidized bed dryer at 90 0 C for 1 h.
• the catalyst prepared by means of the catalyst support according to the invention shows a selectivity S (C 2 H 4 ) of 93.5% and a space-time yield (determined by gas chromatography) of 474 g VAM / 1 catalyst / h at an oxygen conversion of 30%.
• a 0.38 M base mixture consisting of a 50:50 mixture of NaOH: KOH (ie 40.965 g of 0.38 molar NaOH + 40.965 g of 0.38 molar KOH) were added to the carrier beads and overnight Room temperature allowed to stand for 16.5 h.
• the catalyst precursor was reduced with 73.14 g of a 10% NaH 2 PO 2 solution for 2 hours.
• the carrier beads were washed with deionized water for 19 hours at room temperature with constant replacement of the water to remove Cl residues. The final value of the conductivity of the wash water was 4.6 ⁇ S.
• the catalyst was dried in a fluidized bed dryer at 90 0 C for 1 h.
• the dried catalyst was treated with a mixture of 25.25 g a 2 molar KOAc solution and 14.77 g H 2 O uniformly and allowed to stand for 1 h at room temperature. Finally, it was re-dried in a fluidized bed dryer at 90 0 C for 1 h.
• the catalyst prepared by means of the catalyst support according to the invention shows a selectivity S (C 2 H 4 ) of 92.0% and a space-time yield (determined by gas chromatography) of 440 g VAM / 1 catalyst / h at an oxygen conversion of 31%.

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