Classifications

• • 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
• • 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
  • C07C51/215—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of saturated hydrocarbyl groups
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C55/00—Saturated compounds having more than one carboxyl group bound to acyclic carbon atoms
  • C07C55/02—Dicarboxylic acids

Definitions

• the present invention relates to a process for the manufacture of carboxylic acids.
• It relates more particularly to a process for the manufacture of carboxylic acids by oxidation of a hydrocarbon with oxygen or an oxygen-containing gas, and even more particularly to the oxidation of cyclohexane to adipic acid.
• Adipic acid is an important chemical compound used in many fields.
• adipic acid can be used as an additive in many products both in the food sector and in concrete.
• one of the most important uses is
• adipic acid Several methods of manufacturing adipic acid have been proposed.
• One of the most - - - important, used industrially on a large scale; - consists in oxidizing in one or two step (s) the cyclohexane to a mixture of cyclohexanol / cyclohexanone with a gas 15 containing oxygen or with oxygen. After extraction and purification of the cyclohexanol / cyclohexanone mixture, these compounds are oxidized in particular to adipic acid by nitric acid.
• the reaction is carried out in a solvent medium, the solvent being a monocarboxylic acid such as acetic acid.
• a solvent medium such as acetic acid.
• these solvents can have high melting points, in particular higher than room temperature, implying a more complex extraction process or an implementation at high temperatures of the extraction or separation processes.
• One of the objectives of the present invention is to provide a process for the manufacture of carboxylic acids by the oxidation of hydrocarbons using oxygen or an oxygen-containing gas which is effective and easy in the presence of a solvent lipohilic, implementing an effective extraction step of the acids formed and total recycling of the oxidation solvent.
• the invention provides a process for the manufacture of dicarboxylic acids by oxidation with oxygen or a gas containing oxygen from a cycloaliphatic hydrocarbon in the presence of an oxidation catalyst and a solvent d oxidation of lipophilic nature, characterized in that it comprises a step of extraction of the dicarboxylic acids formed in the oxidation step of carrying out, in the liquid phase, an extraction of the diacids using a solvent d extraction in which at least the oxidation solvent and the cycloaliphatic hydrocarbon are not soluble.
• monocarboxylic compounds are preferred.
• the extraction of the diacids formed is carried out in a liquid / liquid extraction column with countercurrent flow.
• the extraction solvent is advantageously chosen from the group comprising polar solvents, water, alcohols such as methanol.
• the preferred solvent is water or a solution mainly containing water.
• liquid-liquid extraction columns suitable for the invention the various principles and devices commonly used in industrial processes can be used. Thus, columns with mechanical disc or mobile agitation, columns using pulsed technology, static columns with perforated trays or with packing are suitable. Preferably, columns with mechanical agitation are preferred.
• this extraction can be implemented in a single extraction column or in several extraction columns mounted in series and / or in parallel without thereby departing from the scope of the invention. It is also possible to use one or more extraction columns in combination with washer-settler devices
• the reaction medium resulting from the oxidation step is fed in the extraction step at conditions of temperature and pressure determined to maintain the cycloaliphatic hydrocarbon in the liquid state .
• the extraction of the diacids is carried out under conditions of temperature and pressure determined to maintain the cycloaliphatic hydrocarbon in the liquid state.
• Maintaining the hydrocarbon in the liquid state during the extraction phase makes it possible to maintain the oxidation solvent in the solubilized state, or to maintain a homogeneous solution between the hydrocarbon and the oxidation solvent.
• a second extraction solvent is supplied to the extraction column against the flow of the first extraction solvent.
• This second solvent is a solvent for the oxidation solvent such as lipophilic monocarboxylic acids and is not miscible with the first extraction solvent. This double extraction allows an almost complete recovery of the oxidation solvent and its recycling.
• This second solvent is chosen from apolar solvents having a solubility in the first extraction solvent less than or equal to 5% by weight relative to the first extraction solvent, this solubility being measured at a temperature of 20 ° C. under atmospheric pressure .
• this second solvent is chosen from acyclic or cyclic saturated hydrocarbons, aromatic hydrocarbons.
• this second solvent is the hydrocarbon to be oxidized, in particular cyclohexane.
• the supply of this second solvent represents at least partially the supply of hydrocarbon to be oxidized in the oxidation process of the invention when the latter is a continuous process.
• the reaction medium is supplied at an intermediate position of the column, the first extraction solvent and the second extraction solvent are supplied respectively at each end of the column.
• the reaction medium is generally obtained from oxidation by oxygen or an oxygen-containing gas, of a hydrocarbon, more particularly of a cycloaliphatic hydrocarbon, arylaliphatics such as cyclohexane, cyclododecane.
• the oxidation reaction is generally carried out in the presence of a solvent.
• This solvent can be very varied in nature insofar as it is not substantially oxidizable under the reaction conditions.
• the solvent is chosen from carboxylic acids of lipophilic nature.
• lipophilic acid compound suitable for the invention means aromatic, aliphatic, arylaliphatic or alkylaromafic acid compounds comprising at least 6 carbon atoms, which may include several acid functions and having low solubility in water, that is to say a solubility of less than 10% by weight at room temperature (10 ° C - 30 ° C).
• lipophilic organic compound there may be mentioned, for example, hexanoic, heptanoic, octanoic, 2-ethyl hexanoic, nonanoic, decanoic, undecanoic, dodecanoic, stearic (octadecanoic) acids and their permethyl derivatives (total substitution of the methylene group hydrogens by the group methyl), 2-octadecylsuccinic acid, 3,5-ditertiobutylbenzoic acid, 4-tertiobutylbenzoic acid, 4-octylbenzoic acid, tertiary butyl hydrogen orthophthalate, naphthenic or anthracene acids substituted by alkyl groups, preferably of the tertiobutyl type, phthalic acids, fatty diacids such as the fatty acid dimer.
• the lipophilic acid solvent is chosen to advantageously obtain a homogeneous phase under the temperature and pressure conditions at which the oxidation reaction is carried out.
• the solubility of the solvent in the hydrocarbon or the reaction medium is at least greater than 2% by weight, and that at least one homogeneous liquid phase comprising at least part of the hydrocarbons to be oxidized and part of the solvent is formed.
• the solvent is chosen from those which are not very soluble in water, that is to say which have a solubility in water of less than 10% by weight at ambient temperature (10-30 ° C.).
• This oxidation is carried out, in general, in the presence of a catalyst.
• This catalyst advantageously comprises a metallic element chosen from the group comprising Cu, Ag, Au, Mg,
• catalytic elements are used either in the form of compounds advantageously at least partially soluble in the liquid oxidation medium under the conditions for carrying out the oxidation reaction, or supported, absorbed or linked to an inert support such as silica , alumina, for example.
• the catalyst is preferably, in particular under the conditions for carrying out the oxidation reaction:
• the catalyst used is soluble in one of these media at room temperature or at the recycling temperature of these media in a new oxidation.
• the catalyst is at least partially soluble in the medium considered.
• the catalytically active metallic elements are supported or incorporated in a micro or mesoporous mineral matrix or in a polymer matrix or are in the form of organometallic complexes grafted onto an organic or mineral support.
• the metal is an element of the support or that one works with complexes sterically trapped in porous structures under the conditions of oxidation.
• the homogeneous or heterogeneous catalyst consists of salts or metal complexes of groups IVb (group of Ti), Vb (group of V), Vllb (group of Cr), Vllb ( Mn group), VIII (Fe or Co or Ni group), Ib (group
• the preferred elements are, in particular, Mn and / or Co which can be used in combination with one or more elements chosen from the group comprising Cr, Zr, Hf, Ce and Fe.
• the metal concentrations in the medium oxidation liquid vary between 0.00001 and 5% (% by weight), preferably between 0.001% and 2
• the concentration of solvent in the reaction medium is advantageously determined so as to have a molar ratio between the number of solvent molecules and the number of metal of catalytic element between 0.5 and 100,000, preferably between 1 and 5000
• the concentration of solvent in the liquid oxidation medium can vary within wide limits. Thus, it can be between 1 and 99% by weight relative to the total weight of the liquid medium, more advantageously it can be between 2 and 50% by weight of the liquid medium.
• nitriles such as acetonitrile, benzonitrile, imides belonging to the family described in patent application Ep 0824962, and more particularly N-hydroxysuccinimide (NHS) or N-hydroxyphthalimide ( NHPI), halogen derivatives such as dichloromethane, fluorinated compounds such as: - Cyclic or acyclic fluorinated or perfluorinated aliphatic hydrocarbons,
• - fluorinated aromatic hydrocarbons such as perfluorotoluene, perfluoromethylcyclohexane, perfluoroheptane, perfluorooctane, perfluorononane, perfluorodecaline, perfluoromethyldecaline, ⁇ , ⁇ , ⁇ -trifluorotoluene, 1,3-bis (methyl trifluoro) benzene).
• Fluorinated or perfluorinated alcohols such as hexanol, octanol, nonanol, perfluorinated decanol, perfluorinated t-butanol, perfluorinated isopropanol, hexafluoro-1, 1,1, 3,3,3-propanol-2.
• Fluorinated or perfluorinated acids such as trifluoromethylbenzoic acids, pentafluorobenzoic acid, hexanoic, heptanoic, octanoic, nonanoic acid, perfluorinated adipic acid.
• Fluorinated halides per ⁇ perfluorinated such as- iodo perfluorinated octane, perfluorinated bromooctane.
• Fluorinated or perfluorinated amines such as perfluorinated tripropylamine, perfluorinated tributylamine, perfluorinated tripentylamine.
• the invention applies more particularly to the oxidation of cycloaliphatic compounds such as cyclohexane, cyclododecane into corresponding linear diacids, adipic acid, dodecanoic acid.
• the invention relates to the direct oxidation of cyclohexane to adipic acid, by an oxygen-containing gas, in a liquid medium and in the presence of a manganese catalyst, in particular a catalyst based on manganese and cobalt.
• the oxidation reaction is carried out at a temperature between 50 ° C and 200 ° C, preferably between 70 ° C and 180 ° C. It can be carried out at atmospheric pressure. However, it is generally carried out under pressure to maintain the components of the reaction medium in liquid form.
• the pressure can be between 10Kpa (0.1 bar) and 20,000 Kpa (200 bar), preferably between 100 Kpa (1 bar) and 10,000 Kpa (100 bar).
• the oxygen used can be in pure form or as a mixture with an inert gas such as nitrogen or helium. It is also possible to use air more or less enriched with oxygen.
• the amount of oxygen supplied to the medium is advantageously between 1 and 1000 moles per mole of compounds to be oxidized.
• the oxidation process can be carried out continuously or according to a batch process.
• the liquid reaction medium leaving the reactor is treated according to the method of the invention allowing on the one hand to separate and recover the diacid produced and on the other hand to recycle the non-oxidized or partially oxidized organic compounds such as cyclohexane, cyclohexanol and / or cyclohexanone, the catalyst and the oxidation solvent.
• a compound which initiates the oxidation reaction such as for example a ketone, an alcohol, an aldehyde or a hydroperoxide.
• Cyclohexanone, cyclohexanol and cyclohexyl hydroperoxide which are reaction intermediates in the case of the oxidation of cyclohexane, are very particularly indicated.
• the initiator represents from 0.01% to 20% by weight of the weight of the reaction mixture used, without these proportions having a critical value. The initiator is especially useful when starting oxidation. It can be introduced at the start of the reaction.
• Oxidation can also be carried out in the presence of water introduced from the initial stage of the process.
• the carboxylic acid recovered after the liquid / liquid extraction step can be purified according to the usual techniques and described in numerous documents, for example by crystallization and recrystallization from different solvents such as water, acetic acid or other organic solvents. Purification processes are described in particular in French patents Nos. 2749299 and 2749300.
• the catalyst is not entirely recycled with the organic phase, and is partly or completely extracted with the aqueous phase, it will advantageously be extracted from the aqueous phase by different techniques such as liquid / liquid extraction, electrodialysis, treatment on ion exchange resin, for example.
• the organic phase recovered from the reaction medium can be subjected to distillation operations for recycling the non-oxidized hydrocarbon, the various oxidation compounds such as alcohols, ketones, the oxidation solvent.
• the organic phase can be subjected to a treatment to remove the esters, in particular before recycling of the solvent.
• the mixture is stirred at 130 ° C, 20 Bar for 150 min under a continuous flow of gas containing nitrogen and oxygen. After consuming 35 L of oxygen, a mixture of cyclohexane, tert-butylbenzoic acid, cyclohexanone, cyclohexanol, manganese and cobalt are added continuously.
• a level probe connected to a reactor emptying system keeps the reactor core constant.
• a section of 200 g of oxidation reaction mixture is isolated.
• a mass of 200 g of water is added to this fraction in a mixer maintained at 70 ° C.
• two phases are recovered: a lower so-called aqueous phase which essentially contains the diacids produced and the catalysis metals and a higher so-called organic phase which essentially contains cyclohexane, tert-butylbenzoic acid, cyclohexanone, cyclohexanol and other reaction byproducts.
• the oxidation stage is identical to that described in Example 1.
• the oxidation reaction medium withdrawn continuously from the reactor is fed into an extraction column with agitated stages having a number of theoretical stages of 10
• the extraction column operates at a temperature of 100 ° C. under a pressure of 5 bar.
• the column is fed at an intermediate stage (fifth stage) by the oxidation reaction medium with a flow rate corresponding to a supply of 1.11 Kg / h of t-BBA and 1.09 Kg / h of acid adipic at a temperature of 100 ° C under a pressure of 5 Bar.
• the column is also supplied, at the top of the column, with water with a flow rate of 1.62 kg / h and at the bottom of the column with a flow of cyclohexane equal to 1.04 kg / h.
• the organic phase recovered at the head of the column comprises 1.11 kg / h of t-BBA, 1.04 kg / h of cyclohexane and 0.007 kg / h of adipic acid.
• the aqueous phase drawn off at the bottom of the column comprises 0.001 Kg / h of t-BBA, 1.62 Kg / h of water and 1.083 Kg / h of adipic acid.

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• 2002
  • 2002-10-30 FR FR0213579A patent/FR2846652B1/fr not_active Expired - Fee Related
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