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• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
  • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
• • 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
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
  • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
  • B01J23/20—Vanadium, niobium or tantalum
  • B01J23/22—Vanadium
• • 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
  • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
  • B01J27/14—Phosphorus; Compounds thereof
  • B01J27/186—Phosphorus; Compounds thereof with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
  • B01J27/195—Phosphorus; Compounds thereof with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium with vanadium, niobium or tantalum
  • B01J27/198—Vanadium
• • 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
  • B01J35/19—Catalysts containing parts with different compositions
• • 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
• • 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
  • B01J35/612—Surface area less than 10 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
  • B01J35/61—Surface area
  • B01J35/613—10-100 m2/g
• • 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
• • 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

Definitions

• the invention relates to catalyst systems for the production of phthalic anhydride by gas phase oxidation of o-xylene and / or naphthalene, and to a process for the preparation of phthalic anhydride using the catalyst systems.
• Phthalic anhydride is produced industrially by catalytic gas phase oxidation of o-xylene or naphthalene in tube bundle reactors.
• the starting material is a mixture of a gas containing molecular oxygen, for example air, and the o-xylene and / or naphthalene to be oxidized.
• the mixture is passed through a plurality of arranged in a reactor tubes (tube bundle reactor), in which there is a bed of at least one catalyst.
• DE-A-2238067 describes the use of two catalyst zones of different activity.
• the active masses differ in the proportion of potassium ions.
• DE-A-19823275 describes a two-layer catalyst system.
• the activity structuring takes place via the amount of active composition on the support and via the amount of added dopants in the form of alkali metal compounds in the active composition (see also WO 03/70680).
• the activity of the individual zones is changed by the amount of phosphorus of the active composition, the amount of active material on the carrier ring, the amount of alkali doping of the active composition and the filling level of the individual catalyst layers in the reaction tube when using three or more catalyst systems.
• WO 98/17608 describes an activity structuring with the aid of different porosity of the various catalyst layers.
• the porosity is determined by the free volume defined between the coated moldings of the bed in the reaction tube.
• titanium dioxide in the anatase modification is the main constituent of the active composition of the phthalic anhydride catalysts and serves to support the catalytically active and selective vanadium pentoxide components in addition to other metal oxides.
• DE-A 21 06796 describes the preparation of supported catalysts for the oxidation of o-xylene to phthalic anhydride, wherein the titanium dioxide has a BET surface area of 15 to 100 m 2 / g, preferably 25 to 50 m 2 / g. It is disclosed that mixtures of anatase BET surface area of 7 to 11 m 2 / g and titanium dioxide hydrate of BET surface area> 100 m 2 / g are particularly suitable, the components alone would not be suitable.
• EP-A 744214 describes a mixture of titanium dioxide having a BET surface area of 5 to 11 m 2 / g and titanium dioxide hydrate having a BET surface area of more than 100 m / g in a mixing ratio of 1: 3 to 3: 1.
• a mixture of titanium dioxides having a BET surface area of 7 to 11 m 2 / g with titanium dioxide hydrate having a BET surface area of> 100 m 2 / g is also described in DE-A 19633757. Both components can be present in a ratio, based on one gram of TiO 2 , of 1: 9 to 9: 1. Furthermore, a mixture of titanium dioxide with titanium dioxide hydrate in a ratio of 3: 1 is described in DE-A 2238067.
• EP-A 522871 describes a relationship between the BET surface area of the titanium dioxide and the catalyst activity.
• the catalyst activity is low when using titanium dioxide with BET surface areas of less than 10 m 2 / g.
• BET surface areas are preferably from 15 to 40 m 2 / g.
• the decrease in the activity of the first catalyst layer with respect to the life of the catalyst has a negative effect.
• sales decline in the range of the first highly selective layer.
• the main reaction zone always migrates throughout the catalyst life deeper into the catalyst bed, ie the o-xylene or Naphthalinfeed is increasingly implemented only in the subsequent less selective layers.
• the result is reduced phthalic anhydride yields and an increased concentration of by-products or unreacted starting materials.
• the salt bath temperature can be steadily raised. As the catalyst life increases, however, this measure also leads to a reduction in the phthalic anhydride yield.
• (i) in the uppermost layer has a BET surface area of 5 to 30 m 2 / g,
• (ii) has a BET surface area of from 10 to 40 m 2 / g in the middle layer (s), and
• the BET surface area of the titanium dioxide in the uppermost layer is smaller than the BET surface area of the titanium dioxide in the middle layer or layers and the BET surface area of the titanium dioxide in the lowest layer is greater than the BET surface area of the titanium dioxide in the middle layer or layers.
• phthalic anhydride can be advantageously prepared using the catalyst system according to the invention.
• the catalyst system preferably consists of three to five layers, in particular of four layers.
• the BET surface area of the Tiandioxide used in anatase modification is as follows:
• the titanium dioxide Preferably, the titanium dioxide
• (ii) in the middle layer (s) has a BET surface area of 10 to 35 m 2 / g, and (iii) has a BET surface area of 15 to 45 m 2 / g in the lowest layer.
• the upper middle layer titanium dioxide (iia) has a BET surface area of 10 to 35 m 2 / g, especially 10 to 30 m 2 / g, and the lower middle layer titanium dioxide (u b) a BET surface area of 15 to 40 m 2 / g, in particular 15 to 35 m 2 / g, on.
• the titanium oxide of the upper middle layer (iia) has, for example, a BET surface area of 10 to 35 m 2 / g, in particular 10 to 30 m / g
• the middle middle layer (u b) a BET surface area of 10 to 40 m 2 / g, in particular 10 to 35 m 2 / g
• the lower middle layer (iic) has a BET surface area of 15 to 40 m 2 / g, in particular 15 to 38 m 2 / g.
• the titanium dioxide used preferably consists in at least one catalyst layer of a mixture of titanium dioxides of different BET surface areas.
• This mixture of titanium dioxide types includes, for example, a low surface area titanium dioxide having a BET surface area of advantageously 5 to 15 m 2 / g, in particular 5 to 10 m 2 / g, and a higher surface area titanium dioxide having a BET surface area of advantageously 10 to 70 m 2 / g, in particular 15 to 50 m 2 / g.
• the titanium dioxide used consists of the two mentioned titanium dioxide types. Compared with the titanium oxide hydrates described in the prior art and their
• the titanium dioxide used advantageously consists of a mixture of a titanium dioxide having a BET surface area of 5 to 15 m 2 / g and a titanium dioxide having a BET surface area of 15 to 50 m 2 / g in a ratio of
• the bed length of the uppermost catalyst layer (i) is advantageously 80 to 160 cm, that of the upper middle catalyst layer (iia) 20 to 60 cm, that of the lower middle catalyst layer (eng) 30 to 100 cm and that of the lowermost catalyst layer (iii) 40 to 90 cm.
• Suitable catalysts are oxidic supported catalysts.
• Suitable catalysts are oxidic supported catalysts.
• phthalic anhydride by gas phase oxidation of o-xylene or naphthalene or mixtures thereof are used generally spherical, annular or cup-shaped carrier of a silicate, silicon carbide, porcelain, alumina, magnesia, tin dioxide, rutile, aluminum silicate, magnesium silicate (steatite),
• Zirconium silicate or cersilicate or mixtures thereof So-called coated catalysts in which the catalytically active composition has been applied to the carrier in the form of a dish have proven particularly useful.
• the catalytically active constituent is preferably vanadium pentoxide.
• a small number of other oxidic compounds which, as promoters, influence the activity and selectivity of the catalyst, for example by lowering or increasing its activity, can be present in the catalytically active composition in small amounts.
• promoters examples include the alkali metal oxides, thallium (I) oxide, alumina, zirconium oxide, iron oxide, nickel oxide, cobalt oxide, manganese oxide, tin oxide, silver oxide, copper oxide, chromium oxide, molybdenum oxide, tungsten oxide, iridium oxide, tantalum oxide, niobium oxide, arsenic oxide, antimony oxide, cerium oxide and phosphorus pentoxide ,
• the alkali metal oxides act, for example, as activity-reducing and selectivity-enhancing promoters.
• the catalytically active composition may contain organic binders, preferably copolymers, advantageously in the form of an aqueous dispersion, of vinyl acetate / vinyl laurate, vinyl acetate / acrylate, styrene / acrylate, vinyl acetate / maleate, vinyl acetate / ethylene and hydroxyl groups.
• organic binders preferably copolymers, advantageously in the form of an aqueous dispersion, of vinyl acetate / vinyl laurate, vinyl acetate / acrylate, styrene / acrylate, vinyl acetate / maleate, vinyl acetate / ethylene and hydroxyl groups.
• ethyl cellulose are added, wherein binder amounts of 3 to 20 wt .-%, based on the solids content of the solution of the active ingredient components were used (EP-A 744214).
• Organic binders are preferably used as described in DE-A 19824532. If the
• the useful coating temperatures are between 50 and 450 ° C. (DE-A 21 06796).
• the applied binder burn after filling the catalyst and start-up of the reactor within a short time.
• the addition of binder also has the advantage that the active material adheres well to the carrier, so that transport and filling of the catalyst are facilitated.
• the reaction gas (starting gas mixture) fed to the catalyst is generally mixed with the oxygen to be oxidized by mixing a molecular oxygen-containing gas which, in addition to oxygen, may still contain suitable reaction moderators such as nitrogen and / or diluents such as steam and / or carbon dioxide Hydrocarbon generated.
• the molecular oxygen-containing gas may generally be 1 to 100 mol%, preferably 2 to 50 mol% and more preferably 10 to 30 mol% of oxygen, 0 to 30 mol%, preferably 0 to 10 mol% of water vapor and 0 to 50 mol%, preferably 0 to 1 mol% carbon dioxide, balance nitrogen.
• the gas containing molecular oxygen is generally charged with 30 g to 150 g per Nm 3 gas, in particular with 60 to 120 g per Nm 3 , of the aromatic hydrocarbon to be oxidized.
• the less active catalyst is placed in a fixed bed such that the reaction gas contacts first with this catalyst and only subsequently with the more active catalyst in the second layer. Subsequently, the reaction gas comes into contact with the still more active catalyst layers.
• the different active catalysts can be thermostated to the same or different temperatures.
• the reaction gas is passed at temperatures of generally from 300 to 450 ° C, preferably 320 to 420 ° C and more preferably from 340 to 400 ° C. It is advantageous to use an overpressure of generally 0.1 to 2.5 bar, preferably 0.3 to 1.5 bar.
• the space velocity is generally 750 to 5000 h ⁇ 1 .
• the hot spot temperature of the uppermost layer is preferably from 400 to 470 ° C., in particular the maximum temperature is below 450 ° C.
• the hot-spot temperature is advantageously less than 420 ° C, in particular less than 410 ° C.
• the catalysts have, for example, the following composition:
• active composition 7 to 10 wt .-% of active composition based on the total catalyst, said active composition: 6 to 11 wt .-% vanadium pentoxide
• an alkali calc. As the alkali metal, in particular cesium oxide and the balance to 100 wt .-% titanium dioxide in anatase modification with a
• active composition 7 to 12 wt .-% of active composition based on the total catalyst, said active composition:
• alkali metal calculated as alkali metal
• an alkali (calculated as the alkali metal), in particular cesium oxide 0.05 to 0.4 wt .-% phosphorus pentoxide (calculated as P) and the balance to 100 wt .-% titanium dioxide, in particular in anatase modification with a BET surface area of 15 to 50 m 2 / g.
• the catalysts have, for example, the following composition: for the first layer (layer (i)):
• an alkali (calculated as alkali metal), in particular cesium oxide, and the remainder to 100% by weight of titanium dioxide in anatase modification with a BET surface area of 5 to 30 m 2 / g
• active composition 7 to 12 wt .-% of active composition based on the total catalyst, said active composition:
• active composition 7 to 12 wt .-% of active composition based on the total catalyst, said active composition:
• vanadium pentoxide 0 to 3% by weight antimony trioxide 0.05 to 0.4% by weight phosphorus pentoxide (calculated as P) and the remainder to 100% by weight titanium dioxide in anatase modification with a BET Surface area of 15 to 50 m 2 / g.
• the service life could be increased by a more uniform reaction heat distribution over the catalyst bed.
• the maximum hot-spot temperature decreases and the Phthalcicreanhydrid- yield can be increased with low by-product concentrations.
• phthalic anhydride can also be produced at high loadings, for example at 80 to 120 g / Nm 3 , with o-xylene and / or naphthalene and at high space velocities with high yield and low concentrations of by-product, in particular phthalide.
• the phthalide concentration is not higher than 0.05% by weight, based on phthalic anhydride.
• the suspension was applied to 1200 g of steatite molded article (magnesium silicate) in the form of rings (7 ⁇ 7 ⁇ 4 mm, OD ⁇ L ⁇ ID) by spraying.
• the weight the applied active mass shell was 8% of the total weight of the finished catalyst.
• the catalytically active composition applied in this manner contained 7.1% by weight of V 2 O 5) 2.4% by weight of Sb 2 O 3 , 0.26% by weight of Cs.
• the BET surface area of the TiO 2 mixture was 22.5 m 2 / g.
• the catalytically active composition applied in this manner contained 7.1% by weight of V 2 O 5 , 2.4% by weight of Sb 2 O 3 , 0.10% by weight of Cs.
• the BET surface area of the TiO 2 mixture was 22.5 m 2 / g.
• the weight of the applied active mass cup was 8.0% of the total weight of the finished catalyst.
• the BET surface area of the TiO 2 mixture was 23.4 m 2 / g.
• the catalytically active composition applied in this way contained 7.1% by weight of V 2 O 5 , 1.8% by weight of Sb 2 O 3 , 0.36% by weight of Cs.
• the BET surface area of the TiO 2 mixture was 16.7 m 2 / g.
• the catalytically active composition applied in this manner after calcining at 400 ° C. for 4 hours, contained 7.1% by weight of V 2 O 5 , 2.4% by weight of Sb 2 O 3> 0.26% by weight of Cs.
• the BET surface area of the TiO 2 mixture was 17.3 m 2 / g.
• Steatitform stresses magnesium silicate
• the weight of the applied active mass shell was 8% of the total weight of the finished catalyst.
• the BET surface area of the TiO 2 mixture was 23, 4 m 2 / g.
• Catalyst 3 4 layers (comparative example)

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  • 2003-05-23 DE DE10323818A patent/DE10323818A1/de not_active Withdrawn
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