Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
  • B01F23/20—Mixing gases with liquids
  • B01F23/23—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids
  • B01F23/2319—Methods of introducing gases into liquid media
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
  • B01F23/20—Mixing gases with liquids
  • B01F23/23—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids
  • B01F23/237—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids characterised by the physical or chemical properties of gases or vapours introduced in the liquid media
  • B01F23/2376—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids characterised by the physical or chemical properties of gases or vapours introduced in the liquid media characterised by the gas being introduced
  • B01F23/23761—Aerating, i.e. introducing oxygen containing gas in liquids
  • B01F23/237612—Oxygen

Definitions

• hydrocarbons In contrast to air, hydrocarbons have the disadvantageous property of detonating in the presence of molecular oxygen. This applies in particular at elevated temperatures and the formation of hydrocarbon films on solid surfaces. In addition, if the oxygen supply is disrupted, there is a risk that hydrocarbons will penetrate and detonate in the oxygen line.
• the technical task was therefore to design the dissolving of molecular oxygen in liquid hydrocarbons in such a way that the risk of detonation was avoided and no sources of danger occur even under extraordinary operating conditions, for example a drop in pressure or failure of the oxygen supply.
• the new method has the advantage that critical operating states are avoided and, particularly in the case of extraordinary operating states such as failure of the oxygen supply, there are no sources of danger.
• the starting materials used are liquid hydrocarbons, in particular alkanes with 4 to 18 carbon atoms, cycloalkanes with 5 to 10 carbon atoms in the ring or alkyl aromatics with 7 to 12 carbon atoms.
• Cycloalkanes of the stated carbon number, in particular cyclohexane, have become particularly important.
• the molecular oxygen used advantageously contains less than 5% by volume, in particular less than 1% by volume, of inert gases, such as nitrogen, carbon dioxide or noble gases.
• the dissolving process is carried out in a vertical absorption zone, e.g. an absorption tower, which advantageously has a length to diameter ratio of 5 to 20: 1
• a layer of water is maintained at the bottom of the absorption zone.
• the water layer advantageously takes up 10 to 50% of the content of the absorption zone.
• the water layer advantageously contains salts such as alkali salts, e.g. Sodium chloride, sodium sulfate or potassium phosphate.
• the salt content is preferably from 50 to 90% by weight of the saturation value.
• the water layer additionally contains surface-active substances such as cationic, anionic or neutral surface-active substances. Suitable surface-active substances are, for example, sulfuric acid or phosphoric acid esters of long-chain alcohols.
• a content of 0.001 to 0.1% by weight of surfactants is generally sufficient.
• the molecular oxygen is advantageously introduced into the water layer in a fine distribution.
• the liquid hydrocarbons are fed into the absorption zone above the water layer.
• the liquid hydrocarbons are advantageously introduced immediately above the water layer.
• the finely divided molecular oxygen rising from the water layer is conducted upwards together with the liquid hydrocarbons with thorough mixing in the absorption zone. Due to the fine distribution of the molecular oxygen in the water layer, it enters the hydrocarbon layer by itself as a result of buoyancy and is present there in a fine distribution. You make sure that none come together hanging gas phase. This is achieved in that the absorption zone is always completely filled with liquid and a small partial stream, for example 0.005 to 0.1 times the total amount of hydrocarbon supplied, is advantageously removed at the top end and stripped with nitrogen. This prevents the formation of a coherent gas phase. The resulting liquid hydrocarbon is added back to the starting hydrocarbon.
• the absorption zone advantageously has, for example, one or up to 6 bottlenecks in the part in which the liquid hydrocarbon is conducted upwards together with molecular oxygen.
• Baffle plates are advantageously arranged between the constrictions. It is also possible to arrange several bottlenecks on one level.
• the narrow points are advantageously designed as nozzle openings, so that the ascending mixture of hydrocarbons and molecular oxygen has a flow velocity of 2 to 60 m / s at the nozzle outlet opening. It has also proven to be advantageous to recycle part of the molecular oxygen solution in hydrocarbons.
• the 2 to 50 times the amount of the solution of molecular oxygen in hydrocarbons, based on the amount of hydrocarbons supplied, is advantageously removed near the upper end of the absorption zone and fed back into the absorption zone at a point immediately above the water layer.
• the absorption is carried out at a temperature of 0 to 50 ° C.
• the temperature is chosen so that it is only a few degrees above the melting point of the water and the hydrocarbon, which is higher.
• a pressure of 10 to 100 bar is advantageously maintained. It is advantageous to ensure that the pressure corresponds to 1.1 to 1.5 times the saturation pressure at the temperature used in each case. So much oxygen is advantageously dissolved in the hydrocarbons that a degree of saturation of 60 to 90% is achieved under the pressure and temperature conditions used in each case.
• solutions of molecular oxygen in liquid hydrocarbons obtainable by the process of the invention are suitable for further reaction in the production of oxidation products, e.g. cyclohexane solutions containing molecular oxygen are used to prepare cyclohexanone and cyclohexanol.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Oxygen, Ozone, And Oxides In General (AREA)

Applications Claiming Priority (2)

Publications (3)

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ID=6269080

Family Applications (1)

Country Status (4)

Cited By (1)

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• 1985
  • 1985-04-25 DE DE19853514924 patent/DE3514924A1/de not_active Withdrawn
• 1986
  • 1986-04-22 DE DE8686105531T patent/DE3680812D1/de not_active Expired - Lifetime
  • 1986-04-22 EP EP86105531A patent/EP0199339B1/fr not_active Expired - Lifetime
  • 1986-04-23 US US06/854,917 patent/US4735741A/en not_active Expired - Lifetime
  • 1986-04-23 JP JP61092439A patent/JPS61247603A/ja active Pending

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