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
  • 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
• • 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 present invention relates to a catalyst system for the production of carboxylic acids and / or carboxylic anhydrides, which has at least four catalyst layers arranged one above the other in the reaction tube, wherein the ratio of the bed lengths of the more selective catalyst layers to the bed lengths of the active catalyst latoratorenlagen between 1.4 to 2 , Furthermore, the present invention relates to a process for gas phase oxidation in which a gaseous stream comprising a hydrocarbon and molecular oxygen, passes through several catalyst layers, wherein the ratio of the bed lengths of the more selective catalyst layers to the bed lengths of the more active catalyst layers 1-4 lies.
• a variety of carboxylic acids and / or carboxylic anhydrides are industrially prepared by the catalytic gas phase oxidation of hydrocarbons, such as benzene, xylenes, naphthalene, toluene or durene, in fixed bed reactors. You can in this way z.
• a mixture of an oxygen-containing gas and the starting material to be oxidized is passed through tubes containing a bed of catalyst. For temperature control, the tubes are surrounded by a heat transfer medium, for example a molten salt.
• hot spots occur in the catalyst bed in which the temperature is higher than in the remaining part of the catalyst bed or in the remaining part of the catalyst bed. These hot spots lead to side reactions, such as the total combustion of the starting material, and can irreversibly damage the catalyst from a certain hot spot temperature.
• the activity of the catalysts or catalyst systems used for the gas phase oxidation therefore decreases with increasing operating time.
• downstream catalyst layers are generally more active but less selective, undesired overoxidation and other side reactions increase. The two effects mentioned cause the product yield to decrease with the operating time.
• CN 1616148 describes a catalyst system for the production of phthalic anhydride.
• the catalysts are mainly composed of V2O5, TiO2, Sb2Ü3 and Cs.
• the catalyst system is divided into four catalyst layers.
• the first, upper most selective catalyst layer has a length of 0.9 to 1, 5 m
• the second catalyst layer has a length of 0.2 to 1, 0 m
• the third catalyst layer has a length of 0.2 to 1 , 0 m on
• the last, most active catalyst layer has a length of 0.2 to 1, 0 m.
• the ratio of the bed lengths of the selective catalyst layers to the bed lengths of the more active catalyst layers is thus between 0.5 and 6.25.
• the example discloses a catalyst system with a packed length of 135/55/80/80 cm.
• the ratio of the bed lengths of the more selective catalyst layers to the bed lengths of the more active catalyst layers is 1.18.
• the initial yield of phthalic anhydride was 114%. At a load of 90g, a yield of> 1 13% could be achieved after one year.
• a process for the preparation of phthalic anhydride is described, are used in the catalyst systems having four catalyst layers, wherein the first, most selective catalyst layer accounts for 27 to 55% of the total bed length of the catalysts, the second catalyst layer 5 to 22% , the third catalyst layer is 8 to 35% and the fourth catalyst layer is 16 to 40%.
• the ratio of the bed lengths of the more selective catalyst layers to the bed lengths of the more active catalyst layers is thus between 0.4 and 3.5.
• a catalyst system with the bed length 130/50/70/70 cm is disclosed.
• the ratio of the bed lengths of the more selective catalyst layers to the bed lengths of the more active catalyst layers is 1, 3.
• the initial yield of phthalic anhydride was 113.5% after 50 days at a loading of 100 g / Nm 3 o-xylene. A long-term test is not revealed.
• the invention is therefore based on the object to provide a catalyst system for gas phase senoxidation, which has a very uniform thermal load of the catalyst system. It is therefore also the object to provide a catalyst system for gas phase oxidation, which provides a high yield of carboxylic acids and / or carboxylic anhydrides at a very high loading of hydrocarbons over a long period of time.
• the object has been achieved by a catalyst system for producing carboxylic acids and / or carboxylic anhydrides which has at least four catalyst layers arranged one above the other in the reaction tube, the ratio of the bed lengths of the more selective catalyst layers to the bed lengths of the more active catalyst layers being between 1, 4 and 2 lies.
• the ratio of the bed lengths of the more selective catalyst layers to the bed lengths of the more active catalyst layers is between 1, 4 and 2, preferably between 1, 5 and 1, 8, in particular between 1, 6 and 1.7.
• the total length of the catalyst bed is usually 2.5 to 4 m, preferably 2.8 to 3.4 m.
• the activity of a catalyst layer is defined as follows: the higher the conversion for a particular reactant mixture at the same salt bath temperature, the higher the activity.
• the selectivity of a catalyst layer is defined as follows: the higher the yield of a specific product at the same salt bath temperature, the higher the selectivity.
• the activity / selectivity of the catalysts can be determined, for example, by adding promoters to the active composition, adjusting the BET surface area of the catalysts, the proportion of active composition, i. be varied by the active material per tube volume, by the space between the individual shaped catalyst bodies or by the content of inert materials.
• the catalytically active composition of all catalysts preferably comprises at least vanadium oxide and titanium dioxide.
• the BET surface area of the catalytically active components of the catalyst is advantageously in the range from 5 to 50 m 2 / g, preferably from 5 to 40 m 2 / g, in particular from 9 to 35 m 2 / g.
• the proportion of active composition is preferably from 3 to 15% by weight, in particular from 4 to 12% by weight, based on the total catalyst mass.
• the activity is controlled by means of the promoter cesium.
• Active catalyst layers typically have a cesium content of ⁇ 0.1 wt .-% based on the active composition.
• Selective catalyst layers typically have a cesium content of> 0.1 wt .-% based on the active composition.
• the second selective layer is advantageously longer than the third and / or fourth catalyst layer.
• the second catalyst layer is preferably at least 5%, in particular at least 10%, longer than the third and / or fourth catalyst layer.
• the first most selective catalyst layer advantageously has a length of 30 to 50% of the total catalyst bed, preferably 35 to 45%; the second catalyst layer advantageously has 18 to 25% of the total catalyst bed, preferably 20 to 23%; and the third and fourth catalyst layers advantageously each have 15 to 22% of the total catalyst bed, preferably 17 to 20%, with the second catalyst bed particularly preferably having a longer bed length than the third and / or fourth catalyst bed.
• the ratio of the first catalyst layer to the second catalyst layer is advantageously less than 2.4, preferably between 1, 6 and 2.2, in particular between 1, 8 and 2.0.
• the catalysts used in the process according to the invention are generally coated catalysts in which the catalytically active composition is applied in the form of a dish on an inert support.
• the layer thickness of the catalytically active composition is generally 0.02 to 0.25 mm, preferably 0.05 to 0.15 mm.
• the catalysts have a cup-shaped active mass layer of substantially homogeneous chemical composition.
• one or more successive two or more different active mass layers can be applied to a carrier. It is then spoken of a two- or multi-layer catalyst (see, for example, DE 19839001 A1).
• the application of the individual layers of the coated catalyst can be carried out by any known methods, for. B. by spraying solutions or suspensions in the coating drum or coating with a solution or suspension in a fluidized bed, as described for example in WO 2005/030388, DE 4006935 A1, DE 19824532 A1, EP 0966324 B1.
• the activity of the catalyst layers advantageously increases from the uppermost catalyst layer (gas inlet side) to the most unfamiliar catalyst layer (gas outlet side). Possibly. could be upstream or intermediate catalysts with a higher activity (European
• Patent application with the file reference 06112510.0 or one or more moderator layers (European patent application with the file reference 06008816.8) can be used.
• the activity of the catalyst layers preferably increases continuously from the gas inlet side to the gas outlet side.
• alkali metal As alkali metal and the remainder TiO 2 in anatase form, d) and the next arranged in the flow direction of catalyst on non-porous and / or porous support material 8 to 12 wt .-%, based on the total catalyst, active composition, containing 10 to 30 wt .-% V 2 O 5 , 0 to 4 % By weight of Sb 2 O 3 or Nb 2 O 5 , 0 to 0.5% by weight of P, 0 to 0.1% by weight of alkali (calculated as alkali metal) and the balance TiO 2 in anatase form .
• alkali metal cesium is preferably used.
• the present invention further relates to a process for gas phase oxidation in which a gaseous stream comprising at least one hydrocarbon and molecular oxygen is passed through at least four catalyst layers arranged one above the other in the reaction tube, the ratio of the bed lengths of the more selective catalyst layers to the bed lengths of the more active catalyst layers between 1, 4 and 2 lies.
• the process according to the invention is advantageously suitable for the gas-phase oxidation of aromatic C 6 -C 10 -hydrocarbons, such as benzene, xylenes, toluene, naphthalene or durene (1, 2,4,5-tetramethylbenzene) to carboxylic acids and / or carboxylic anhydrides, such as maleic anhydride, phthalic anhydride, benzoic acid and / or or pyromellitic dianhydride.
• aromatic C 6 -C 10 -hydrocarbons such as benzene, xylenes, toluene, naphthalene or durene (1, 2,4,5-tetramethylbenzene)
• carboxylic acids and / or carboxylic anhydrides such as maleic anhydride, phthalic anhydride, benzoic acid and / or or pyromellitic dianhydride.
• the process is particularly suitable for the preparation of phthalic anhydride from o-xylene and / or naphthalene.
• the gas-phase reactions for the preparation of phthalic anhydride are generally known and are described, for example, in WO 2004/103561 on page 6.
• the catalysts are prepared as described in the European patent application with the file reference 06112510.0 in the examples. After calcining the catalyst for one hour at 450 ° C., the active composition applied to the steatite rings was 8.0%.
• the analyzed composition of the active composition consisted of 7.1% V 2 O 5 , 1.8% Sb 2 O 3 , 0.36% Cs, balance TiO 2 .
• the active composition applied to the steatite rings was 8.5%.
• the analyzed composition of the active composition consisted of 7.1% V 2 O 5 , 2.4% Sb 2 O 3 , 0.1% Cs, balance TiO 2 .

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Catalysts (AREA)
• Furan Compounds (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=38440253

Family Applications (1)

Country Status (6)

Families Citing this family (12)

Citations (11)

Family Cites Families (5)

• 2007
  • 2007-05-14 US US12/301,420 patent/US20090163726A1/en not_active Abandoned
  • 2007-05-14 CN CNA2007800181289A patent/CN101448571A/zh active Pending
  • 2007-05-14 JP JP2009511456A patent/JP2009537316A/ja active Pending
  • 2007-05-14 EP EP07729073A patent/EP2024085A1/de not_active Withdrawn
  • 2007-05-14 WO PCT/EP2007/054621 patent/WO2007135002A1/de not_active Ceased
  • 2007-05-18 TW TW096117820A patent/TW200745017A/zh unknown

Patent Citations (11)

Also Published As

Similar Documents

Legal Events