Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C37/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring
  • C07C37/50—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring by reactions decreasing the number of carbon atoms
  • C07C37/56—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring by reactions decreasing the number of carbon atoms by replacing a carboxyl or aldehyde group by a hydroxy group
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/50—Improvements relating to the production of bulk chemicals
  • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P30/00—Technologies relating to oil refining and petrochemical industry
  • Y02P30/20—Technologies relating to oil refining and petrochemical industry using bio-feedstock

Definitions

• the invention relates to a process for the preparation of a phenol by an oxidative decarboxylation in the gas phase of a corresponding arylcarboxylic acid in the presence of a Cu-containing catalyst.
• GB-A-762738 which is an equiavlent of NL-B-90.684 already discloses such a process, wherein the oxidation, the decarboxylation as well as the hydrolysis are effected in a single process step, at a temperature of at least 200°C, preferably 230-250°C.
• the process according to the invention provides a process for the preparation of a phenol from the corresponding arylcarboxylic acid in the gas phase, with virtually complete prevention of tar formation.
• a process is obtained which combines high preparation selectivities with an economically attractive embodiment.
• the process according to the invention is characterized in that the following process steps are carried out: a) Supplying an oxidant-containing gas mixture to the catalyst bed under such conditions that tar formation virtually absent, b) Supplying arylcarboxylic acid and steam with exclusion of oxygen, resulting in formation of gaseous phenol.
• arylcarboxylic acid is understood to be a compound having the following structure:
• R 1 through R 5 may be hydrogen (on the proviso that at least R 1 or R 5 is hydrogen) or organic groups, which have a so-called Hammett constant of between -1 and +2.
• a description of this Hammett or ⁇ value, which represents a measure of the influence of the group on the reactivity of the arylcarboxylic acid, can be found in J. March, Advanced Organic Chemistry 1989, pages 242-250; see in particular table 4 on page 244.
• the groups that can be used therefore are: C j ⁇ -Cg alkyl, cylcoalkyl, aryl, arylalkyl, amino, halogen, nitro.
• Esters and anhydrides of (I) are also suitable, while the groups may also be connected with each other via ring system, as is the case for instance in naphthalene carboxylic acid (substituted or not).
• Multiple arylcarboxylic acids, such as trimellitic acid and pyromellitic acid, can also be used as starting material. Mixtures of the arylcarboxylic acids described above can also be used in the process according to the invention.
• the oxidation of the Cu-containing catalyst involving conversion of copper into Cu(II), is a first reaction step in the process. It brings about an increase in the degree of oxidation of the copper.
• the oxidation of the copper-containing catalyst proceeds well particularly when carried out using an oxygen-containing gas. Air, whether or not enriched with oxygen or oxygen-depleted, can very well be used for this. Other oxidizing gases can also be used, e.g. N 2 0- or
• no tar is formed.
• This can be achieved by various measures. For instance it can be ensured that no phenol is absorbed to the catalyst any more, hence that the catalyst is essentially free of phenol. This can be accomplished by stripping with steam or an inert gas at the end of the second step. Or for instance the temperature of the catalyst bed in this step can be kept below 200°C, preferably between 150-190°C (because the rate of oxidation of Cu is high and tar formation does not occur until the temperature exceeds 200°C, in the presence of phenol). It is also possible to apply a higher temperature (e.g. 191-270°C) and keep the contact time between the reaction mixture and the oxygen short (e.g. 0.1-5 minutes), so that not all the copper is converted into the Cu(II) form.
• the catalyst can be applied onto a carrier, consisting for instance of oxides of silicon, titanium or cadmium, of for instance of carbon.
• the catalyst is used immobilized on a carrier.
• Silica is preferably used as carrier.
• the catalyst load will as a rule be 5-40 wt.% metal on carrier.
• a high degree of loading contributes to a high conversion per volume unit.
• This co-catalyst can be chosen in particular from groups III through VIII as well as from the group of the lanthanides and actinides of the Periodic System of the Elements. These components have an effect on the oxidative capacity of the Cu in the catalyst.
• the catalyst used may for instance consist of copper, zirconium and, if desired, an alkali metal or an alkali earth metal such as sodium, potassium, lithium or magnesium. Also, rare earths (atom numbers 37 through 71) or zirconium, silver, vanadium, chromium, molybdenum, hafnium and tungsten or mixtures thereof in combination with copper can be used.
• the second step in the process according to the invention comprises a combination of a reduction and the formation of phenol, in which process carbondioxide (C0 2 ) is released.
• the pressure under which the second process step is performed is not critical, but the advantage of raising the pressure to above atmospheric level is that it has a favourable effect on the reaction kinetics.
• the pressure to be applied will generally be between 0.1 and 2.5 MPa; higher pressures, though allowable, do not yield substantial improvements of the process.
• reaction products are subjected to an upgrading operation in order to separate and recover the phenol obtained. This can be done in ways known by themselves, for instance by distillation.
• the bottom flow of the distillation which may contain non-converted arylcarboxylic acid, can be recycled to the process, optionally after a purification step.
• the catalyst can be applied in the form of a fixed or moving beds.
• the two-step reaction can be carried out intermittently, successively supplying for a short time an oxygen-containing gas to e.g. a fixed-bed reactor and then - with exclusion of oxygen - having the second step take place.
• the oxidative gas mixture can be supplied again.
• the two-step process can also be carried out continuously by having the oxidation step take place in the first reactor of a multiple reactor system and then bringing the catalyst, preferably in a moving bed, to a second reactor, where the second step takes place. In that case the reactors can be fully adapted to the desired requirements.
• the process according to the invention is suitable in particular for the preparation of unsubstituted phenol from unsubstituted benzoic acid.
• This phenol can be used for instance as starting material both for phenol-formaldehyde resins and for the preparation of caprolactam, starting material for nylon-6, or for the preparation of bisphenol-A. 5
• the invention will now be elucidated in the following examples, which should not be construed as limiting the invention.
• Tests were performed using a set-up as represented in the annexed diagram, in which A represents a steam-generating device (H 2 0/N 2 mixture), B a benzoic acid evaporator and C an air supply device. The three flows go to the reactor bed in D. E, F and G are coolers, cooling the
• H is the analysis section for the offgas mixture.
• the reactor consisted of a packed bed of about 2.5 ml, filled with copperoxide on silica.
• the gas flows from A, B and C were adjustable, products in E through H were analyzed using gas
• the catalyst was oxidized with air for 30 seconds.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

Priority Applications (6)

Applications Claiming Priority (2)

Publications (1)

Family

ID=3885569

Family Applications (1)

Country Status (12)

Citations (1)

• 1991
  • 1991-06-14 BE BE9100582A patent/BE1004950A4/nl not_active IP Right Cessation
• 1992
  • 1992-06-03 TW TW081104391A patent/TW224087B/zh active
  • 1992-06-10 WO PCT/NL1992/000101 patent/WO1992022519A1/en not_active Application Discontinuation
  • 1992-06-10 JP JP5500809A patent/JPH06508616A/ja active Pending
  • 1992-06-10 AU AU22752/92A patent/AU2275292A/en not_active Abandoned
  • 1992-06-10 BR BR9206152A patent/BR9206152A/pt not_active Application Discontinuation
  • 1992-06-10 SK SK1407-93A patent/SK140793A3/sk unknown
  • 1992-06-10 FI FI935588A patent/FI935588L/fi unknown
  • 1992-06-10 CZ CS932690A patent/CZ269093A3/cs unknown
  • 1992-06-10 EP EP92914859A patent/EP0588973A1/en not_active Withdrawn
• 1993
  • 1993-12-14 BG BG98301A patent/BG98301A/xx unknown
• 1994
  • 1994-11-11 EE EE9400222A patent/EE9400222A/xx unknown

Patent Citations (1)

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